Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/02—Polishing compositions containing abrasives or grinding agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/04—Aqueous dispersions
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F3/00—Brightening metals by chemical means
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
  • H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
  • H01L21/321—After treatment
  • H01L21/32115—Planarisation
  • H01L21/3212—Planarisation by chemical mechanical polishing [CMP]

Definitions

• This invention relates to an improved composition and process for the chemical mechanical polishing or planarization of semiconductor wafers. More particularly, it relates to such a composition and process tailored to meet more stringent requirements of advanced integrated circuit fabrication.
• CMP Chemical mechanical polishing (or planarization)
• ILD inter-layer dielectrics
• MLM multilayered metal
• the National Technology Roadmap for the Semiconductor Industries (1994) indicates that the current computer chips with 0.35 micron feature sizes will be reduced to 0.18 micron feature size in 2001.
• the DRAM chip will have a memory of 1 gigabit, and a typical CPU will have 13 million transistors/cm 2 (currently they only contain 4 million).
• the number of metal layers (the "wires") will increase f om the current 2-3 to 5-6 and the operating frequency, which is currently 200 MHZ, will increase to 500 MHZ. This will increase the need for a three dimensional construction on the wafer chip to reduce delays of the electrical signals.
• the CMP process would appear to be the simple rotation of a wafer on a rotary platen in the presence of a polishing medium and a polishing pad that grinds (chips away) the surface material.
• the CMP process is actually considered to be a two part mechanism: step one consists of chemically modifying the surface of the material and then in the final step the altered material is removed by mechanical grinding.
• the challenge of the process is to control the chemical attack of the substrate and the rate of the grinding and yet maintain a high selectivity (preference) for removing the offending wafer features without significant damage to the desired features.
• the CMP process is very much like a controlled corrosion process.
• EKC electronic Chemography
• Some of these compositions and processes are also useful for removing photoresist, polyimide, or other polymeric layers from substrates in integrated circuit fabrication, and EKC has also developed a variety of compositions and processes specifically for removing such polymeric layers from substrates in integrated circuit fabrication. Additionally, EKC has developed a variety of compositions and processes to selectively remove specific substrate compositions from a substrate surface at a controlled rate. Such compositions and processes are disclosed in the following commonly assigned issued patents:
• Ethylenediaminetetraacetic acid or its ammonium salt semiconductor process residue removal process
• Stripping compositions comprising hydroxylamine and alkanolamine
• Triamine positive photoresist stripping composition and prebaking process Triamine positive photoresist stripping composition and prebaking process
• Hydroxylamme (HA) formulations have been found to be useful in the removal of substrate, for example as an etchant used in chemical-mechanical etching processes, as described in U.S. Patent Nos. 6,313,039; 6,251,150; and 6,117,783.
• Hydroxylamine formulations have also been useful in removing photoresists, such as is found in U.S. Patent Nos. 5,279,771 and 5,381,807, which describe formulations containing hydroxylamine, an alkanolamine, and optionally a! polar organic solvent.
• Hydroxylamine formulations have also been useful in removing etching residue, such as is found in U.S. Patent No. 5,334,332, which describes a formulation containing hydroxylamine, an alkanolamine, water, and a chelating agent. Hydroxylamine-containing formulations designed to remove residues are known to be aggressive to metals, particularly to titanium film and under more aggressive process conditions to aluminum film.
• the attack of titanium can be moderated by using different chelator, e.g., such as disclosed in
• U.S. Patent No. 6,276,372 and /or by selecting a class of alkanolamine with 2-carbon linkage(s), which is disclosed, e.g., in U.S. Patent No. 6,121,217.
• other formulations include those disclosed in: U.S. Patent Nos. 6,276,372, 6,221,818, and
• U.S. Patent No. 5,997,658 to Peters et al. describes a hydroxlamine-free photoresist stripping and cleaning composition, for use particularly of copper or titanium [0044] substrates, having about 70 to 85% by weight of an alkanolamine, about 0.5 to
• Alkanolamines include N-methylethanolamine (NMEA), monoethanolamine (MEA), diethanolamine, mono-, di-, and tri- isopropanolamine, 2-(2-aminoethylamino)-ethanol, 2-(2-aminoethoxy)-ethanol, triethanolamine, and the like.
• the preferred alkanolamine is N-methylethanolamine (MEA).
• U.S. Patent No. 5,928,430 to Ward et al. entitled Aqueous stripping and cleaning compositions containing hydroxylamine and use thereof, describes an aqueous stripping composition comprising a mixture of about 55% to 70% by weight of a polar amine solvent, about 22.5 to 15% by weight of a basic amine, especially hydroxylamine, gallic acid as a corrosion inhibitor, and water.
• U.S. Patent No. 5,928,430 to Ward et al. entitled Aqueous stripping and cleaning compositions containing hydroxylamine and use thereof, describes an aqueous stripping composition comprising a mixture of about 55% to 70% by weight of a polar amine solvent, about 22.5 to 15% by weight of a basic amine, especially hydroxylamine, gallic acid as a corrosion inhibitor, and water.
• 5,419,779 to Ward describes a stripping composition containing water, 22.5 to 15% by weight of hydroxylamine, 55% to 70% monoethanolamine, and preferably up to about 10% by weight of a corrosion inhibitor, particularly one selected from the group consisting of catechol, pyrogallol, anthranilic, acid, gallic acid, and gallic ester.
• a corrosion inhibitor particularly one selected from the group consisting of catechol, pyrogallol, anthranilic, acid, gallic acid, and gallic ester.
• the polishing slurries are a critical part of the CMP process.
• the polishing slurries consist of an abrasive suspension (silica, alumina, etc.) usually in a water solution.
• the type and size of the abrasive, the solution pH and presence of (or lack of) oxidizing chemistry are very important to the success of the CMP process.
• Metal CMP slurries must have a high selectivity for removing the unwanted metal compared to the dielectric features on the wafers.
• the metal removal rate should be between 1700 to 3500 A/min) without excessive "dishing" of the metal plugs or erosion of the oxide substrate.
• the oxide CMP has similar requirements and polishing rates close to 1700 A/min.
• metal polishing selectivity to oxide generally ranges from 20 to 100:1, depending on the metal type. Tungsten metal should have selectivities >50:1 for the metal to oxide, and copper could have > 140:1 metal to oxide selectivity. Etch rates can be up to 7000 A/min. The chemical diffusion rate and the type of metal oxide surface are important to the successful planarization process. A detailed mechanism has been proposed by Kaufman.
• the low pH and highly corrosive oxidants (ferric nitrate) being used with an example metal CMP process has created corrosion problems with the polishing equipment.
• the oxidant used in the metal polishing step has ranged from nitric acid to hydrogen peroxide, cesium and ferric nitrate solutions and even ferric cyanide solutions. Because of chemical stability problems, many slurries are made up at the point of use which means that there is little or no shelf life.
• Metal planarization needs an oxidizing reagent that is stable and is not going to contribute to mobile ion contamination, will not "stain” the equipment, will not affect the slurry composition and slurry particle distribution and is generally environmentally friendly.
• the current hydrogen peroxide systems are not stable when premixed with the slurry and therefore have to be delivered to the polishing equipment with separate pumping systems and mixed at the point of use.
• the ferric nitrate system requires a low pH and is known to "stain" the polishing equipment.
• the potassium iodate system also requires special handling.
• An emerging area of CMP will deal with the copper damascene process.
• the copper metal interconnects (wires) will be required because of its better conductivity compared to Al.
• One major disadvantage with copper is its easy diffusion through silica under normal operating conditions.
• the copper damascene process will need barrier layers to prevent this copper diffusion.
• barrier materials are etched into the interdielectric layers, and then the walls of these trenches are coated with barrier materials. These materials can be composed of Ta, TaN, Ti or TiN among other materials. Copper metal is then deposited, by electroless or electrode plating, or PVD or CVD methods. The excess copper above the trench is then removed by chemical mechanical polishing. The difficult part of the CMP process is not to remove excess copper ("dishing") which will remove the copper metal below the interdielectric layer.
• CMP of the copper metal can be done over a wide pH range (2 to 12).
• Pourbaix diagrams for copper indicate that copper can only be passivated (oxide layer) in neutral or basic solutions.
• an inhibitor e.g., benzotriazole (BTA)
• BTA benzotriazole
• Much of the CMP work has been done with hydrogen peroxide at various pH ranges.
• Some CMP work has been done with ammonium hydroxide, because of its ability to form copper complexes though there are problems with poor selectivity between copper and titanium and silicon oxide.
• polishing process appears to involve two concurrent processes; a mechanical process involving plastic deformation of the surface and, chemical attack by hydroxide (-OH) to form silanol bonds.
• the silicon surface There are other important features of the silicon surface that will influence the etch rates and final surface conditions; (metal contamination and possibly micro scratches).
• the typical silicon surface is terminated (covered) with -OH groups under neutral or basic conditions.
• the silicon surface is hydrophilic (the surface is "wettable”). These groups activate the surface to a number of possible chemical or physioabsorbtion phenomena.
• the Si-OH groups impart a weak acid effect which allows for the formation of salts and to exchange the proton (H + ) for various metals (similar to the ion exchange resins).
• These Si-O " and Si-OH can also act as ligands for complexing Al, Fe, Cu, Sn, and Ca.
• the surface is very dipolar and so electrostatic charges can accumulate or be dissipated depending on the bulk solution's pH, ion concentration and charge. This accumulated surface charge can be measured as the Zeta potential.
• silica (Si) surface underneath the oxide layer is exposed because of an over aggressive polishing process, this could cause electrochemical problems because silica has a modest redox potential which will allow Cu, Au, Pt, Pb, Hg and Ag to "plate on” the silica surface. Exposure to light will also affect the redox reaction for Cu. The light will "generate” electrons in the semiconductor Si material which then reduces the copper ion to Cu°.
• One aspect of the present invention relates to a chemical mechanical polishing composition for polishing a metal, a metal oxide, and/or a metal nitride layer of a substrate, which composition is typically substantially free of abrasive particles and can include: a hydroxylamine derivative; a corrosion inhibitor; and water.
• water can be the majority of the composition. In one embodiment, the water is present in a total amount from about 90% to about 99% by weight of the composition.
• the composition may further contain a sufficient amount of an acid and/or a base to adjust the pH of the composition to a desired level.
• the acid and/or base are present in a total amount from about 0.01% to about 2% by weight of the composition.
• the composition is substantially free of acid and or base to adjust the pH.
• the chemical mechanical polishing composition according to the invention may further include, or alternately be substantially free from one or more of the following: hydroxylamine, acid and or base to adjust pH, two carbon atom linkage alkanolamine compounds, quaternary ammonium salts, chelating agents, organic solvents, non-hydroxyl- containing amine compounds, surfactants, additional oxidizing agents, and non-abrasive additives.
• the hydroxylamine derivative includes hydroxylamine nitrate, hydroxylamine sulfate, and/or hydroxylamine. In another embodiment, the hydroxylamine derivative is present in a total amount from about 1% to about 5% by weight of the composition.
• the corrosion inhibitor includes benzotriazole. In another embodiment, the corrosion inhibitor consists essentially of benzotriazole. In another embodiment, the corrosion inhibitor is present in a total amount from about 0.01% to about 0.05% by weight of the composition.
• the chemical mechanical polishing composition according to the invention can be substantially free of abrasive particles and can consist essentially of: about 1% to about 5% by weight of a hydroxylamine derivative selected from the group consisting of hydroxylamine, hydroxylamine nitrate, hydroxylamine sulfate, and mixtures thereof; about 0.01% to about 0.05% by weight of benzotriazole; about 90% to 99% by weight of water; and less than about 2% by weight of an acid and/or a base to adjust the pH of the composition to a desired level.
• the composition is substantially free of hydroxylamine.
• Another aspect of the invention relates to a process for chemical mechanical polishing of a substrate including the steps of: providing a substantially abrasive-free chemical mechanical polishing composition according to the invention; contacting the chemical mechanical polishing composition with a substrate having a dielectric layer surface, upon which dielectric surface a barrier layer is disposed, upon which barrier layer a metal layer is disposed; and chemically mechanically polishing the substrate by contacting the substrate surface with an abrasive polishing pad, preferably at an applied pressure of not more than about 2 psi, and by moving the pad in relation to the substrate.
• the metal layer includes copper.
• the metal layer can include tungsten, aluminum, polysilicon, or the like, or a combination thereof.
• the barrier layer can be based on a refractory metal such as tantalum and/or may include a metal nitride (and preferably includes tantalum nitride). In an alternate embodiment, the barrier layer can be titanium-based.
• the removal rate during the CMP step of the barrier layer can be greater than about 500 A/min, less than about 750 A/min, or both;
• the removal rate during the CMP step of the dielectric layer can be less than about 10 A/min, preferably less than about 5 A/min, for example not more than about 1 A/min;
• the removal rate of the metal layer during the CMP step can be less than about 250 A/min, greater than about 10 A/min, or both.
• the removal rate of the metal layer during the CMP step can be less than about 500 A/min, greater than about 50 A/min, or both.
• Figures 1 and 2 are Pourbaix diagrams for copper and metal, useful for an understanding of the invention. DEFINITIONS
• the phrases "contains substantially no” and “is substantially free from,” in reference to a composition should be understood to mean: [0080] for components such as abrasives, alkanolamines including AEEA, polar organic solvents including non-hydroxyl-containing amines, water, organic solvents, hydroxylamine and hydroxylamine derivatives, the aforementioned phrases should be understood to mean that the composition contains less than 1.5%, preferably less than about 1%, more preferably less than about 0.1 %, of the specific element mentioned thereafter; [0081] for minor components including chelating agents, corrosion inhibitors, surfactants, and the like, the aforementioned phrases should be understood to mean that the composition contains less than 0.2%, preferably less than about 0.1%, most preferably less than about 0.01%, of the specific element mention thereafter; and
• substantially free is defined in the specification, e.g., less than 10 ppm metals and metal ions.
• the composition is completely free of any added element specifically mentioned thereafter, or at least does not contain the added element in an amount such that the element affects the efficacy, storability, usability regarding necessary safety concerns, or stability of the composition.
• a compound should generally not be characterized under more than one enumerated element of the composition according to the invention. If a compound is capable of being characterized under, for example, two enumerated embodiments of the composition, such a compound maybe characterized herein only under either one of the two enumerated elements, but not under both. At times, the distinction may be made based on the content of the compound in the composition.
• catechol or gallic acid can act primarily as a corrosion inhibitor at "high" concentrations, i.e. about 0.5% to 20%, or primarily as a metal chelator at "low” concentrations, i.e., in the ppm to 0.5 wt% range.
• hydroxylamine and hydroxyamine derivatives are not considered organic, despite the organic substituents that may be present on substituted hydroxylamine.
• This invention does not deal with the composition or type of abrasive (slurry particle size, shape, size distribution % solids) in the slurry. But the slurries have numerous other components (oxidizing agents, stabilizers, etc.) that can be improved through additional experiments. These components include solutions pH, type of chemistry and chemical and slurry purity. This proposed invention focuses on the chemistry and its possible pH, Zeta potential, contact angle ("wetting") and other associated effects.
• the first phase of the invention focuses on understanding the CMP chemistry based on hydroxylamine (HDA) and hydroxylamine derivatives (the chloride, sulfate, nitrate or other salts) under different pH conditions
• HDA ⁇ H 2 OH
• HDA is a hybrid between hydrazine (H 2 N-NH 2 ) and hydrogen peroxide (H O ) in its redox chemistry.
• HDA is a more selective (controllable) oxidation and reducing agent. This dual capability is achieved by shifting the pH from the acid to basic media, as shown below.
• Cu +2 ( ⁇ H 4 OH) — > Cu " pH 9-11 E v -0.08 Reduction
• E v -0.34 Oxidation
• HDA like ammonia, can form complex salts with many metals including Al(SO ) 2 *NH 2 OH* H 2 O and Cu (x) 2 *NH 2 OH *H 2 O.
• Another important advantage of using hydroxylamine type compounds is their decomposition products. Depending on the solution pH and metal ions and concentration, HDA will decompose to water, nitrogen, ammonia andN 2 0. The formation of nitrogen even takes place through a slow internal redox reaction at pHs above 8.
• the metals currently being studied for the CMP process include Al, Cu, and
• Pourbaix diagrams can be used to examine the best regions (E v versus pH) for the various polishing rates (corrosion). No two metal or alloy systems will have the same regions of chemical activity. Using this data may also allow CMP polishing conditions to be chosen so that the selectivity of the polishing rate of one metal is significantly greater than another metal (or oxide or nitride material) on the same wafer. Pourbaix diagrams can be obtained for all metals, oxides, nitrides and other materials appearing on wafer surfaces wherever they are available. By overlaying the diagrams, pH regions can be roughly determined which may be corrosive for one material while passivating for another. This could be one tool that is useful in seeking high selectivities.
• Figure 1 shows the Pourbaix diagram for Cu.
• thermodynamic data shows that copper, copper (I) oxide and copper (II) oxide can exist together in the redox environment of our world (delineated by the sloping parallel dashed lines). The data also shows that none of these three compounds can exist at pHs less than 6.8, and at oxidation potentials above -0.2 volts, all of these compounds will dissolve. [0094] At higher pH values the three compounds can exist in aqueous solution, including with various anions (Cu(OH) and CuO 2" ).
• This invention proposes that usage of HDA or its salts can be used to remove copper using CMP methods.
• E v -1.05 volts
• Figure 2 shows the Pourbaix diagram for aluminum metal.
• the data shows that the pure metal Al cannot exist in the normal redox regime but only as an oxide coating. Between a pH of 4 and 10 this oxide layer will not dissolve.
• chelating agents e.g., alkyl beta-diketones (2,4 pentanedione, etc.) or EDTA or aromatic phenolic aldehydes (salicylaldehyde, etc.) or other agents.
• These components can be added in concentrations ranging from 2 ppm to 15 wt%. Higher concentrations could be used but there is a possibility that these chelators could "plate” on the chip's structures, or would alter the effectiveness of the over all chemistry.
• the ketone-based systems may react with the hydroxylamine based products to form oxime derivatives which are good chelating agents in their own right.
• Other agents could include bis(hydroxypropyl)hydroxylamine, anisaldehyde or even alpha hydroxy isobutyric acid as a chelator.
• Other compounds could also be aromatic dioxygenated compounds, benzoin and benzil.
• a recently reported water soluble iron chelator is O-TRENSOX which can be used in the HDA-based chemistries and should show promising results.
• catechol and catechol derivatives are known to be good chelating agents at high pH conditions (because of the mono or dianion) only a little work has been done with this class of compounds under acidic conditions. There are reports that catechol will complex with aluminum at pH 3-5.
• Gallic acid is also another compound that under mildly acidic conditions could have complexing powers with certain Group 3 through 12 metals (IUPAC nomenclature).
• the catechol and gallic acid family of compounds can act as either corrosion inhibitors (at
• HDA-based chemistries are the environment, safety and health aspects.
• HDA under basic conditions decomposes to water, nitrogen, and small concentrations of NH 3 .
• HDA is mildly caustic compared to other nitrogen containing compounds, i.e., organic amines.
• hydroxylamine compounds are very stable in aqueous solutions.
• CMP users do not like working with sodium or potassium hydroxide because of the potential mobile ion contamination. Many users have changed over to ammonium hydroxide which does not have the same magnitude of a mobile ion problem and does have a lower surface tension (better surface contact). The main problem with ammonium hydroxide is its odor which requires very effective ventilation systems.
• the Zeta potential is a electrostatic potential measurement of the interaction of the electrostatic double layer ions (anions and cations) that exists around each particle in a solution.
• the Zeta potential depending on the type of particle; i.e. aluminum, silica, manganese dioxide etc., and the solution pH, can be positive or negative. Poorly designed slurries may have a Zeta potential which leads to settling of the slurry particles. This can be very detrimental to its performance during the CMP polishing process.
• Another measure of Zeta potential is the isoelectric point (IEP) for a particle.
• the IEP is the pH at which the Zeta potential value is zero.
• the chemical composition and source will have significant effect on the IEP.
• Some metal residue IEP values are 9.5 for TiO , while tungsten is somewhere around ⁇ 1. Such wide ranges of values pose a major challenge to developing chemistries to control the Zeta potential of the particles that may eventually adhere to the wafer surface.
• Another concern is that the Zeta potential between the slurry and metal particles and the wafer will be such that the particles will be attracted and adhere to the wafer surface. This will require that a post CMIP clean step remove the adhering particles.
• the hydroxylamine or hydroxylamine salts can react with the particle surface through either a redox reaction or a normal chemical reaction with the terminal groups on the surface. Since the HDA chemistries can be chemically "tuned” by adjusting the pH and still be active for metal CMP (see Cu idea above), this will give us a wider process window to affect the solution slurry Zeta potential. Concentrations for this effect should be between 1 to 10 wt% because of HDA' s single charge.
• Another way to change the Zeta potential is to use surfactants (nonionic, cationic or anion) to reduce the surface charge on the wafer.
• the hydroxylamine chemistries can be matched with the appropriate surfactant.
• octylphenol polyethylene (9-10 ethylene oxide units) at pH 9.5 did reduce the surface tension and also reduced surface roughness.
• Anionic surfactants can be used for particles that have positive Zeta potentials.
• Some of the films currently being planarized include TEOS, BPSG, PSG and
• the HDA free base material should be tested at various pH's (7-11) with a silica slurry.
• the amount of HDA used in the slurry should be ⁇ 2 to 10% o .
• SLMS data should show that the mobile ion content remained constant or was decreased.
• ammonium hydroxide solutions will also polish the silicon surface, the vapors from the polishing process need to be handled (removed) in an effective manner.
• HDA chemistries do not have the same smell intensity.
• colloidal silica is very sensitive to pH and undergoes flocculation at pH values near 8, due to the presence of insufficient alkali ions.
• Ammonium bifluoride is another important ingredient to be evaluated in the above matrix.
• Silica dioxide has several solubility regions depending on pH. Ammonium bifluoride at low concentrations (>1X10 "3 molar) and low pH (4-6) can be effective for expanding the "window” for dissolving silica structures. This chemistry region might open up an entirely new CMP processing window for ILD. The concentration ranges must be rather narrow, i.e., 1X10 " to 1X10 " molar. At higher concentrations the chemistries start to act as conventional HF etching media (in the pH range 4-7) with very rapid etching.
• Nitride appears to undergoing slow oxidation to a silicon oxide type compound which undergoes the standard oxide polishing process. This reduces the desired polishing selectivity.
• the HDA free base is a saturated nitrogen solution, and the free base reacts with oxygen thus creating a solution with very poor oxidizing potentials, it is possible that the nitride structures will not be readily attacked. Thus the oxide to nitride polishing selectivity should be enhanced.
• HDA and HDA related compounds can effect the particle and wafer surfaces through pH and redox chemistries, these chemical species only have a single ionic charge per molecule (though a reasonable charge density for the size of molecule involved). It may be necessary to augment the electrostatic double layer around the particles or on the wafer by adding "polyelecfrolytes" which are highly charged compounds. Normally the polyelecfrolytes are used in high enough concentration to "force" particles to clump together. In this invention we only want to add enough polyelecfrolytes encourage the particles to repel each other and away from the wafer surfaces. This will enhance the post CMP cleaning step. The concentration for this affect could range from 1 part per thousand to 10 wt%.
• redox reagents that also can be used in CMP applications which could be used by themselves or in conjunction with other chemistries, including hydroxylamine and its salts.
• ammonium peroxydisulfate can be used to remove Al, copper or tungsten using CMP methods. Though ammonium persulfate has been used to strip copper metal films from electronic component boards, this material has not been used to remove Cu in a very controlled manner. We are not aware of this chemistry being used to polish Al metal under CMP process conditions.
• WO 4 tungstate
• the current CMP processes are based on ferric nitrate or hydrogen peroxide under acid conditions
• ferric nitrate or hydrogen peroxide under acid conditions another feasible route to obtain this species is to oxidize the W metal with an oxidizing agent under basic conditions.
• the tungstate should have maximum solubility at pH >6.
• Normally ammonium persulfate solutions have a pH in the range of 2 to 3. This invention illustrates that by adjusting the oxidizing solution's pH to higher values, the resulting solution will be a very effective for polishing W metal films.
• a polishing composition is optionally but preferably substantially abrasive-free and can contain: optionally hydroxylamine; optionally at least one additive for controlling pH, e.g., an acid; at least one corrosion inhibitor, preferably a copper corrosion inhibitor, such as a copper (I) corrosion inhibitor and/or a copper (II) corrosion inhibitor, more preferably including benzotriazole or a salt or derivative thereof; water; and at least one hydroxylamine derivative having the following formula:
• R 3 is hydrogen or a linear, branched, or cyclic hydrocarbon containing from 1 to 7 carbon atoms; and wherein X and Y are, independently, hydrogen or a linear, branched, or cyclic hydrocarbon containing from 1 to 7 carbon atoms, or wherein X and Y are linked together form a nitrogen-containing heterocyclic C 4 -C 7 ring.
• X, Y, and R 3 are all hydrogen, the compound is hydroxylamine.
• hydroxylamine examples include, but are in no way limited to, hydroxylamine, N-methyl-hydroxylamine, N,N-dimethyl- hydroxylamine, N-ethyl-hydroxylamine, N,N-diethyl-hydroxylamine, methoxylamine, ethoxylamine, N-methyl-methoxylamine, and the like.
• hydroxylamine is not an organic, and the boiling point and flash point of hydroxylamine and hydroxylamine derivatives is of no consequence to the formulation.
• hydroxylamine and its derivatives are available (and may be included in a composition according to the invention) as salts, e.g., sulfate salts, nitrate salts, phosphate salts, or the like, or a combination thereof, and the invention includes these forms of hydroxylamine compounds and their derivatives. These salts greatly increase the theoretical flash point of hydroxylamine derivatives. Therefore, in another embodiment, the composition contains hydroxylamine, a sulfate, nitrate, or phosphate salt of hydroxylamine, or a combination thereof. Hydroxylamines may not be desired in a subset of the formulations described herein. Therefore, in some embodiments, the composition according to the invention is substantially free from hydroxylamine.
• the composition according to the invention contains water.
• hydroxylamine is commercially available in an aqueous, i.e., a 50% aqueous, solution. Hydroxylamine derivatives are typically available in more concentrated aqueous forms, for example, 82% solutions with 18% water (as is the case with HAN, or hydroxylamine nitrate). However, hydroxylamine and/or hydroxylamine derivatives can be obtained or manufactured, in some instances and in some concentrations, in a water-free formulation.
• the composition can contain an acid, e.g., to adjust the pH.
• the acid maybe inorganic (e.g., hydrochloric, hydrobromic, sulfuric, sulfurous, nitric, nitrous, phosphoric, phosphorous, or the like, or a combination thereof), organic (e.g., lactic, acetic, formic, propionic, butyric, benzoic, ascorbic, carbonic, gluconic, maleic, malonic, oxalic, succinic, tartaric. citric, gallic, a polycarboxylic acid such as EDTA, or the like, or a combination thereof), or a combination thereof.
• organic e.g., lactic, acetic, formic, propionic, butyric, benzoic, ascorbic, carbonic, gluconic, maleic, malonic, oxalic, succinic, tartaric. citric, gallic, a polycarboxylic acid such as EDTA, or the like, or a combination thereof
• acids according to the invention may include salts of acids that still have acid functional moieties, e.g., a hydrogen ascorbate, a hydrogen carbonate, a hydrogen gluconate, a hydrogen maleate, a hydrogen malonate, a hydrogen oxalate, a hydrogen succinate, a hydrogen tartarate, a hydrogen citrate, a dihydrogen citrate, a hydrogen gallate, a dihydrogen gallate, a mono-, di-, or tri- substituted salt of EDTA, or the like, or a combination thereof.
• the composition can contain a base to adjust the pH.
• the base may be inorganic (e.g., a completely substituted salt of an inorganic acid, such as those mentioned above; hydrazine or a derivative thereof; a hydroxide salt, such as ammonium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, calcium hydroxide, or the like, or a combination thereof; or the like; or a combination thereof), organic (e.g., a completely substituted salt of an organic acid, such as those mentioned above; a non-hydroxyl-containing amine, such as a substituted or unsubstituted aminobenzene, a substituted or unsubstituted pyridine, a substituted or unsubstituted pyrrole, a substituted or unsubstituted pyrrolidine, a substituted or unsubstituted pyrrolid(in)one, a substituted or unsubstituted carbazole, a substituted or unsubstituted indole, or the like
• Ri , R 2 , R 3 , and R_t are independently hydrogen; a hydroxyl group; optionally a substituted C_-C 6 straight, branched or cyclic hydrocarbon group; optionally a substituted acyl group, straight or branched alkoxy group, amidyl group, carboxyl group, alkoxyalkyl group, alkylamino group, alkylsulfonyl group, or sulfonic acid group; or single or multiple quaternary ammonium salts of such compounds.
• compositions according to the invention typically contains a corrosion inhibitor.
• composition according to the invention contains a single corrosion inhibitor, which is preferably benzotriazole.
• corrosion inhibitors useful in the composition of the invention can be hydroxybenzenes according to the formula:
• the corrosion inhibitors can be dihydroxybenzene isomers and/or alkyl substituted dihydroxybenzenes.
• the preferred corrosion inhibitors are 1,2- dihydroxybenzene and or l,2-dihydroxy-4-tert-butylbenzene.
• corrosion inhibitors as known in the art can also be used in the composition of the present invention.
• corrosion inhibitors which are substantially metal-ion-free can be utilized, such as thiophenol or its derivatives according to the formula: where R_ is preferably a hydrogen, hydroxyl, or carboxylic acid group; or an ethylenediamine tetracarboxylic acid (EDTC), or a salt thereof, having the formula:
• Ri, R 2 , R and R. can be either H, or NRsR ⁇ / s, where R 5 , ⁇ , R 7 , and Rs are each independently hydrogen or a linear or branched C ⁇ -C 6 hydrocarbon, or where two or more of
• the EDTC can be mono-, di- or tri- substituted rather than tetra-substituted. For example, when each of q, r, s, and t are
• the EDTC above is ethylenediamine tetraacetic acid (EDTA).
• EDTA ethylenediamine tetraacetic acid
• Examples of other corrosion inhibitors include, but are not limited to, nitrate salts of ammonium; hydrocarbon-substituted ammonium nitrate salts; a choline, bischoline, and/or trischoline salt, e.g., such as a hydroxide, a bisulfite, or the like; 2,4-pentandione dioxime; l,6-dioxaspiro[4,4] nonane 2,7-dione (di-ether); thiourea; ammonium bisulfite; glycerol; sorbitol; gelatine; starch; phosphoric acid; silicic acid; polyethylene oxide; polyethylene imine; and the like; or a combination thereof.
• nitrate salts of ammonium such as a hydroxide, a bisulfite, or the like
• 2,4-pentandione dioxime such as a hydroxide, a bisulfite, or the like
• the corrosion inhibitors are substantially free of metals and/or metal ions.
• the composition can optionally include at least one two carbon atom linkage alkanolamine compound.
• the generic two carbon atom linkage alkanolamine compounds suitable for inclusion in the invention have the structural formula,
• Y are, independently in each case, hydrogen, a -C linear, branched, or cyclic hydrocarbon, or a group having the formula -CRi R ⁇ '-CR 2 R 2 '-Z-F, with F being either -O-R 3 or -NE ⁇ i, where t is defined similarly to i, Ri', R 2 , R 2 ', and R 3 above, and with Z, Ri, Ri', R 2 , R 2 ', and R 3 defined as above, or wherein X and Y are linked together form a nitrogen-containing heterocyclic C 4 -C 7 ring.
• the two carbon atom linkage alkanolamine compounds have relatively low boiling points and relatively low flash points.
• the two carbon atom linkage alkanolamine compounds that may be useful in the present invention preferably have relatively high boiling points (e.g., 185°C or above, preferably 200°C or above, alternately 215°C or above) and preferably have relatively high flash points (e.g., 95°C or above, preferably 100°C or above, alternately 110°C or above).
• relatively high boiling points e.g., 185°C or above, preferably 200°C or above, alternately 215°C or above
• relatively high flash points e.g., 95°C or above, preferably 100°C or above, alternately 110°C or above.
• Preferred specific examples of such two carbon atom linkage alkanolamine compounds include AEEA and 2-(2-aminoethoxy) ethanol (“DGA").
• AEEA or N-hydroxyethyl-ethylenediamine
• AEEA is the most preferred of the two carbon atom linkage alkanolamine compounds, though it maybe admixed with other two carbon atom linkage alkanolamine compounds to achieve a particular result, such as increased etching or lower cost.
• Examples of other two-carbon atom linkage alkanolamine compounds include, but are in no way limited to, 2-aminoethanol (“monoethanolamine” or “MEA”), 2-(N- methylamino) ethanol (“monomethyl ethanolamine” or “MMEA”), 2-amino-l-propanol
• MIPA 2-(N-hydroxyethyl-amino)-ethanol
• DEA 2-(N-hydroxyethyl-amino)-ethanol
• DEA 2-[(2-aminoethyl)-(2-hydroxyethyl)-amino]-ethanol
• TAA N,N,N-tris-(2-hydroxyethyl)-arnmonia
• N-aminoethyl-N'-hydroxyethyl-ethylenediamine N,N'- dihydroxyethyl- ethylenediamine
• the composition can contain a two-carbon atom linkage alkanolamine compound, in which m is greater than or equal to 1.
• the composition can contain a two-carbon atom linkage alkanolamine compound, in which m is 1 and Ri, Ri', R 2 , R 2 ', and R 3 are all hydrogen or a C ⁇ -C 4 linear or branched hydrocarbon, hi an alternate embodiment, the composition can contain a two-carbon atom linkage alkanolamine compound, in which: m is 1; R 1 ⁇ Ri', R 2 , R 2 ', and R 3 are all hydrogen or a Ci- C 4 linear or branched hydrocarbon; and Q is -NR 3 .
• the composition can contain a two-carbon atom linkage alkanolamine compound, in which: m is 1; Ri, Ri', R 2 , R 2 ', and R 3 are all hydrogen; X and Y are, independently, hydrogen or a linear or branched C ⁇ -C 4 hydrocarbon; and Q is -NH-, -NCH -, or -N[(C 2 -C 4 ) linear or branched hydrocarbon]-.
• the composition may be substantially free from two carbon atom linkage alkanolamine compounds.
• the corrosion inhibitor when present, the corrosion inhibitor (particularly in the form of an EDTC, catechol, or gallic acid) enhances the ability of the two carbon atom linkage alkanolamine compound (when present) to clean/polish the substrate.
• the EDTC, catechol, gallic acid, or other corrosion inhibitor can help to prevent attack on the metal or metal alloy substrate, e.g., copper.
• the composition can contain a quaternary ammonium salt, e.g. , as represented by the following formula:
• Ri, R 2 , R 3 , and R_j are independently hydrogen; optionally a substituted C ⁇ -C 6 straight, branched or cyclic hydrocarbon group; optionally a substituted acyl group, straight or branched alkoxy group, amidyl group, carboxyl group, alkoxyalkyl group, alkylamino group, or alkylsulfonyl group, sulfonic acid group; or the salt of such compounds; and wherein the [counterion] " may be a monovalent, divalent, trivalent, or tetravalent anion and is preferably a monovalent anion.
• the composition may be substantially free from quaternary ammonium salts.
• Examples of monovalent anions for use as a counterion to a quaternary ammonium salt according to the invention include, but are not limited to, hydroxyl groups, nitrate groups, bisulfite groups, bicarbonate groups, carboxylate groups having structures based on singly de-protonated carboxylic acid groups (e.g., formate, acetate, propionate, butyrate, isobutyrate, benzoate, naphthoate, or the like, or singly de-protonated forms of multiply protic carboxylic acids, such as lactate, ascorbate, glyconate, oxalate, malonate, fumarate, maleate, phthalate, isophthalate, terephthalate, gluconate, succinate, glutarate, tartrate, salicylate, glycerate, citrate, gallate, subgallate, or the like), or other acids listed herein, or the like, or a combination thereof.
• the composition according to the invention optionally contains a chelating agent.
• the composition according to the invention contains a single chelating agent, which is preferably EDTA (or a non-metallic salt thereof), another organic polyacetic acid compound (or a non-metallic salt thereof), gallic acid, or catechol.
• Catechol has a boiling point of 245°C, and a flash point of 127°C.
• the composition according to the invention contains a mixture of two chelating agents, such as catechol and gallic acid.
• the composition according to the invention contains a mixture of two chelating agents, preferably catechol and a polyacetic acid such as EDTA, or its corresponding salt.
• the composition is substantially free from chelating agents.
• chelatmg agents include, but in no way limited to, mono-, di-, or multi- hydroxybenzene-type compounds, e.g., such as catechol, resorcinol, butylated hydroxytoluene ("BHT"), and the like, or a combination thereof.
• the chelators include three or more carboxylic acid-containing moieties, e.g., such as ethylenediamine tetraacetic acid (“EDTA”), non-metallic EDTA salts, and the like, or a combination thereof.
• EDTA ethylenediamine tetraacetic acid
• Compounds containing a two carboxylic acid moieties, such as citric acid are less preferred.
• Aromatic compounds containing thiol groups e.g., such as thiphenol; amino-carboxylic acids; diamines, e.g., such as ethylene diamine; polyalcohols; polyethylene oxide; polyamines; polyimines; or a combination thereof, are useful in one embodiment.
• two or more chelating agents can be used in one composition, where the chelating agents are selected from groups described above. Alternately or additionally, some chelating agents are described in U.S. Patent No. 5,417,877, issued May 23, 1995 to Ward, and in commonly assigned U.S. Patent No. 5,672,577, issued September 30, 1997 to Lee, the disclosures of each of which are incorporated herein by reference.
• Catechol can, in one embodiment, act as both a chelating agent and as a corrosion inhibitor.
• the composition according to the invention optionally contains a polar organic solvent.
• the compositions is substantially free of polar organic solvent.
• polar organic solvents for the composition according to the invention include, but are in no way limited to, dimethyl sulfoxide, ethylene glycol, ethylene glycol alkyl ether, diethylene glycol alkyl ether, triethylene glycol alkyl ether, propylene glycol, propylene glycol alkyl ether, dimethyl sulfoxide, N-substituted pyrrolidone such as N-methyl-2-pyrrolidone (NMP), sulfolanes, dimethylacetamide, and the like, or any combination thereof.
• NMP N-methyl-2-pyrrolidone
• Dimethylsulfone CAS No. 126-33-0, with a boiling point of 237°C, is preferred in some embodiments of the invention.
• NMP with a boiling point of 199-202°C and a flash point of only 96°C, may be useful in some embodiments because of low cost. ⁇ MP does, however, tend to lower the flash point of mixtures of the present invention.
• DMSO with a boiling point of 189°C and a flash point of only 95°C, is less preferred in some embodiments of the invention.
• 2,4- dimethylsulfolane with a boiling point of 280°C and a flash point of 143°C, is preferred in some embodiments of the invention.
• amines particularly alkanolamines and also particularly low molecular weight amines, are separate from, and are not classified as, a polar organic solvent.
• additional polar organic solvents as known in the art, other than those specifically excluded, can also be used in the composition of the present invention.
• the composition according to the invention is substantially free from polar organic solvents as defined herein.
• non-polar organic solvents are not preferred, though high boiling alcohols and the like may be used.
• Organic solvents including polar organic solvents, that have a boiling point less than about 100°C are undesirable in the composition according to the invention, as they tend to evaporate over a period of more than about 24-48 hours at operating conditions.
• the composition according to the invention can be substantially free of organic solvents, particularly that have a boiling point less than about 100°C. It is more preferred that the composition according to the invention be substantially free of organic solvents that have a boiling point less than about 150°C. It is even more preferred that the composition according to the invention be substantially free of organic solvents that have a boiling point less than about 199°C.
• the composition according to the invention optionally contains an amine compound that is not a hydroxyl-containing amine and is not an alkanolamine.
• the composition is substantially free of amines that are not hydroxyl-containing amines and that are not alkanolamines.
• amine compounds include, but are in no way limited to, o-diaminobenzene, p- diaminobenzene, N-(2-aminoethyl)-ethylenediamine (“AEEDA”), piperazine, N-substituted piperazine derivatives, piperidine, N-substituted piperidine derivatives, diethylene triamine, 2-methyleneaminopropylenediamine, hexamthylene tetramine, and the like, or a combination thereof.
• the non-hydroxyl-containing amine compound(s) has(have) a boiling point no less than about 100°C, or alternately no less than about 150°C.
• the composition according to the invention can be substantially free from non- hydroxyl-containing amine compounds, or non-hydroxyl-containing amine compounds having boiling points no less than about 100°C, or alternately no less than about 150°C.
• the composition according to the invention also contains a surfactant.
• the composition is substantially free of surfactant. Examples of surfactants include, but are in no way limited to, sodium laurel sulfate, sodium stearate, and the like, or a combination thereof.
• the composition according to the invention also contains an additional oxidizing agent (i.e., other than any hydroxylamine, hydroxylamine derivatives, pH-controlling acids/bases, two carbon atom linkage amine compounds, non-hydroxyl- containing amines, quaternary ammonium salts, and/or other components present in the composition that may serve to oxidize at least a portion of one or more of the layers on the substrate).
• an additional oxidizing agent i.e., other than any hydroxylamine, hydroxylamine derivatives, pH-controlling acids/bases, two carbon atom linkage amine compounds, non-hydroxyl- containing amines, quaternary ammonium salts, and/or other components present in the composition that may serve to oxidize at least a portion of one or more of the layers on the substrate.
• the composition is substantially free of additional oxidizing agents.
• additional oxidizing agents include, but are not limited to: acids and/or salts having halide ions, i.e., including ammonium and alkyl substituted ammonium halides; acids and/or salts having halate (e.g., HalO 4 "x ions, where Hal is a halogen atom and (-x) is the ionic charge) ions, i.e., including ammonium and alkyl substituted ammonium halates; acids and/or salts having metalate (e.g., MO 4 "x ions, where M is ametal atom, such as chromium., manganese, copper, gallium, molybdenum, or the like, and wherein (-x) is the ionic charge) ions, i.e., including ammonium and alkyl substituted ammonium metalates; acids and or salts having borate ions, i.e., including ammonium and alkyl substituted ammonium halides; acids and
• acids and or salts having nitrate ions i.e., including ammonium and alkyl substituted ammonium nitrates (e.g., ferric nitrate, sodium nitrate, calcium nitrate, copper nitrate, nickel nitrate, aluminum nitrate, potassium nitrate, nitric acid, or the like, or a combination thereof); acids and/or salts having nitrite ions, i.e., including ammonium and alkyl substituted ammonium nitrites (e.g., ferric nitrite, sodium nitrite, calcium nitrite, copper nitrite, nickel nitrite, aluminum nitrite, potassium nitrite, nitrous acid, or the like, or a combination thereof); acids and/or salts having phosphate ions, i.e.,
• the composition according to the invention also contains an additional non-abrasive additive.
• additional additives may be spherical, discotic, elliptical, irregular, or any other shape, dense, porous, hollow, e.g., in the form of a particle, agglomerate, foam, flake, fiber/whisker, or the like, or any combination thereof), but must be substantially non-abrasive to the substrate and/or layer(s) (e.g., metal oxide, metal nitride, etc.) disposed thereon.
• additional non-abrasive particulate additives include, but are not limited to: polymeric additives such as rubber particles, polyurethane foams, or the like; sources of carbon such as carbon black particles, mica, or the like; relatively soft metal oxides such as iron oxide or the like; hydrated metal oxides (e.g., metal hydroxides and/or oxide hydroxides) such as aluminum hydroxides and/or oxide hydroxides (e.g., gibbsite, bayerite, nordstrandite, doyleite, boehmite, diaspore, carboirite, rankamite, simpsonite, bahianite, alumotungstite, meixnerite, hydrocalumite, kuzelite, and the like), iron hydroxides and/or oxide hydroxides (e.g., including bernalite, goethite, lepidocrocite, feroxyhyte, ferritungstite, akaganeite, derbylite
• the amount of hydroxylamine derivatives (including hydroxylamine, when present) in the composition according to the invention can be from about 0.1% to about 50%, preferably from about 0.2% to about 20%, alternately from about 0.5% to about 10%, for example from about 0.5% to about 5% or from about 5% to about 10%.
• the amount of hydroxylamine in the composition according to the invention can be expressed in a ratio, relative to the amount of hydroxylamine derivative(s) present in the composition according to the invention.
• the hydroxylamine:hydroxylamine derivative weight ratio can be from about 1:20 to about 20:1, for example from about 1:20 to about 1:1 or from about 1:1 to about 1:20, alternately from about 1:5 to about 1:1 or from about 1:10 to about 1:2.
• the hydroxylamine:hydroxylamine derivative molar ratio can be from about 1:54 to about 8:1, alternately from about 1:54 to about 1:2.7 or from about 1:2.7 to about 8:1, for example from about 1:13.5 to about 1:2.7 or from about 1:2.7 to about 1.9:1.
• the amount of corrosion inhibitor in the composition according to the invention can be from about 0.01% to about 10%, preferably from about
• 0.01% to about 2% more preferably from about 0.01%> to about 1%, for example, from about
• 0.01% to about 0.05% or from about 0.01% to about 0.1%, or alternately from about 0.1% to about 1%.
• the amount of water in the composition according to the invention can advantageously be the majority of the composition, e.g., from about 50% to about 99%, preferably from about 60% to about 98%), for example from about 75% to about
• the amount of acid and/or base added into the composition according to the invention can advantageously be sufficient to adjust the pH of the composition to the desired level.
• a particular amount of acid and/or base to adjust the pH is not specified herein, although it is generally less than about 5%, for example, less than about
• the amount of two-carbon atom linkage alkanolamine compound in the composition according to the invention can advantageously be from about 0.1% to about 15%, alternately from about 0.01% to about 5%, from about 0.2% to about 10%, from about 0.1% to about 1%, or from about 0.5% to about 5%.
• the amount of chelating agent in the composition according to the invention can advantageously be from about 0.01% to about 15%), for example, from about 0.1% to about 10%, alternately from about 0.01% to about 1%, from about 0.01% to about 0.1%, from about 2% to about 8%, or from about 1% to about 5%.
• the amount of quaternary ammonium salt in the composition according to the invention can advantageously be from about 0.01% to about 15%, for example, from about 0.1% to about 10%, alternately from about 0.01% to about 1%, from about 0.01 °/o to about 0.1%, from about 2% to about 8%, or from about 1% to about 5%.
• the amount of organic solvent in the composition according to the invention can advantageously be from about 0.1% to about 25%, for example from about
• the amount of polar organic solvent in the composition according to the invention can advantageously be from about 0.1% to about 20%, for example, from about 0.1% to about 10%>, alternately from about 0.5% to about 10%, from about 2% to about 8%, or from about 1% to about 5%.
• the amount of non-hydroxyl-containing amine in the composition according to the invention can advantageously be from about 0.01% to about 15%, for example, from about 0.1%> to about 10%, alternately from about 0.01% to about 1%, from about 0.01% to about 0.1%, from about 2% to about 8%o, or from about 1% to about 5%.
• the amount of surfactant in the composition according to the invention can advantageously be from about 0.01%) to about 10%, for example, from about 0.1% to about 5%, or alternately from about 0.01%> to about 1% or from about 1% to about 10%.
• the amount of additional oxidizing agent in the composition according to the invention can advantageously be from about 0.1% to about 10%, for example, from about 0.5%> to about 5%, alternately from about 1% to about 10%, from about 2% to about 8%, or from about 1% to about 5%.
• the amount of non-abrasive additives in the composition according to the invention can advantageously be from about 0.1% to about 25%, for example from about 0.5% to about 15%, alternately from about 0.1% to about 10% or from about 5% to about 20%.
• compositions according to the invention have very low metal impurity/ion contents, i.e., not more than about 10 ppm total.
• the compositions according to the invention have not more than about 5 ppm total metal content, preferably not more than about 1 ppm total metal impurity and metal ion content.
• the composition according to the invention contains: substantially no abrasive particles, a hydroxylamine derivative, a corrosion inhibitor, water, optionally hydroxylamine, optionally an acid and/or abase (e.g., to adjust pH), optionally a two carbon atom linkage alkanolamine compound, optionally a quaternary ammonium salt, optionally a chelating agent, optionally an organic solvent, optionally a non- hydroxyl-containing amine compound, optionally a surfactant, optionally an additional oxidizing agent, and optionally a non-abrasive additive.
• the composition according to the invention can be substantially free of one or more of the following: abrasive particles, hydroxylamine, acid and or base to adjust pH, two carbon atom linkage alkanolamine compounds, quaternary ammonium salts, chelating agents, organic solvents (polar and or non-polar), non-hydroxyl-containing amine compounds, surfactants, additional oxidizing agents, and non-abrasive additives.
• compositions according to the invention are preferably substantially free of abrasive particles
• the processes according to the invention may advantageously include the use of an abrasive (e.g., an abrasive pad or the like), but preferably not abrasive particles.
• the present invention relates to a process for chemical mechanical polishing of a substrate including: providing a substantially abrasive- free chemical mechanical polishing composition as described above; contacting the chemical mechanical polishing composition with a substrate having a dielectric material surface (e.g., a metal oxide layer), upon which dielectric material a barrier layer is disposed, upon which barrier layer a metal layer is disposed; and chemically mechanically polishing the substrate by contacting the substrate surface with an abrasive polishing pad, preferably at an applied pressure of not more than about 2 psi and by moving the pad in relation to the substrate.
• the metal layer includes copper.
• the metal layer can include tungsten, aluminum, polysilicon, or the like, or a combination thereof.
• the barrier layer can be based on a refractory metal such as tantalum and/or may include a metal nitride (and preferably includes tantalum nitride).
• the barrier layer can be titanium-based.
• the removal rate during the CMP step of the barrier layer can be greater than about 500 A/min, less than about 750 A/min, or both;
• the removal rate during the CMP step of the dielectric layer can be less than about 10 A/min, preferably less than about 5 A/min, for example not more than about 1 A min;
• the removal rate of the metal layer during the CMP step can be less than about 250 A/min, greater than about 10 A/min, or both.
• the removal rate of the metal layer during the CMP step can be less than about 500 A/min, greater than about 50 A/min, or both.
• EXAMPLE 1 Solutions of ammonium persulfate were prepared and then added to a 5% alumina slurry. The pHs were adjusted with NaOH just before use. [0180] The CMP experiments were with 10,000A tungsten wafers, at 33 rpm and 2 psig. The pad was a Rodell RC 1000 on a Logitech P5M polisher. Base line polishing experiments with only an alumina slurry have determined that there is an 8X to 10X polishing factor between the Logitech and the IPEC/Westech industrial size CMP polisher.
• EXAMPLE 2 [0182] Test: Mother composition that was tested was composed of ammonium persulfate (APS) with varying concentrations of malonic acid (MA). The pH was adjusted with sodium hydroxide. Ammonium hydroxide will be oxidized to nitrogen and water.
• APS ammonium persulfate
• MA malonic acid
• Bases that can be used to adjust the oxidizing solution's pH include sodium hydroxide, potassium hydroxide, magnesium hydroxide, magnesium carbonate, and imidazole, among others.
• oxidizer compounds that can be included; e.g. , peroxy-monosulfuric acid (Caro's acid) (H 2 SO 5 ) or its salts are very strong oxidizing agents,
• the acid form has one proton with a dissociation constant similar to sulfuric acid while the second proton has a pKa of only 9.4.
• Caroat potassium peroxomonosulfate compound, including the potassium salt of Caro's acid; empirical formula 2KHSO 6 KHSO 4 K 2 SO 4 ) is a good oxidizer in aqueous system at low pH, but combined with APS, it shows promising results for W CMP at higher pH values.
• CAROAT is a registered product of Degussa Corporation.
• APS combined with malonamide shows W removal rates comparable with those of APS + malonic acid using the Logitech PM5 polisher (33 rpm, 12"
• perborates such as sodium perborate tefrahydrate are good compounds which are indirect sources for hydrogen peroxide.
• the teraborate has a 10.5% active oxygen content.
• This compound has a different stability than hydrogen peroxide and therefore could be an important compound for CMP metal etching applications.
• the dry form of the perborate salt is used in many bleaching applications, including detergent formulations, tooth powders and denture cleaners.
• another compound that will be of interest will be the urea hydrogen peroxide complex which will permit a more controlled introduction of the oxidizing chemistry into the slurry system.
• another commercially available oxidizing agent that could effective for planarization tungsten or copper metal is peracetic acid.
• the decomposition products include only oxygen and acetic acid (vinegar).
• the polishing conditions were with a Logitech P5M polisher with a Politex felt cloth at 33 rpm and 2 psig pressure on the 3" wafer.
• Another unique idea is to blend two different chemistries to achieve synergistic interactions.
• Two possible chemicals that could be blended are hydrogen peroxide and hydroxylamine.
• Another aspect of the invention is to blend two different chemistries to achieve synergistic interactions.
• Two possible chemical that could be blended are ammomum persulfate and potassium periodate. Potassium periodate has a higher oxidation level compared to the potassium iodate.
• a similar chemistry to that of the previous aspect uses a synergism between ammonium persulfate (APS) and periodic acid (rather than potassium periodate) for polishing tungsten.
• APS ammonium persulfate
• periodic acid rather than potassium periodate
• Removal rates of W generally increase with pH for the periodic acid (H 5 IO 6 ) in water without APS on 3" wafers coated with sputtered W (10,000 A) using 1% or 2.5% alumina (10 or 25 parts of 10% alumina + 90% water slurry), 0-3 parts NH 4 OH to adjust pH, chemistry and slurry combined together at a chemistry/slurry addition rate of 50-100 mL/min, and the Logitech PM5 polisher (33 rpm, 12" ICIOOO pad, 2 psig):
• Periodic acid in water added to APS increases the removal rate of W over APS alone at pH 1; increasing the amount of periodic acid used with 10 parts APS also increases the W removal rate using the Logitech PM5 polisher (33 rpm, 12" ICIOOO pad, 2 psig), 3" wafers (10,000 A sputtered W), 0-3 parts NH4OH to adjust pH, 1% alumina (10 parts of 10% alumina + 90% water slurry), and chemistry/slurry addition rate of 100 mL/min: APS (pph) Periodic Acid (PPh) pH Removal Rate (A/min) 0 2.0 2.4 130 10 2.0 1.1 386 10 0.5 3.5 118 10 2.0 5.2 388 10 0 6 112
• the aqueous potassium periodate (KIO 4 ) system shows a synergistic effect when combined with APS and shows even a greater removal rate for W than the potassium iodate system.
• NaOH (0-3 parts) was used to adjust pH.
• Operating conditions included using the Logitech PM5 polisher 33 rpm, 12" IC 1000 pad, 2 psig), 3" wafers (10,000 A sputtered W), 5% alumina (50 parts of 10% alumina + 90% water slurry), chemistry addition rate of 90 mL/min, and slurry addition rate of 20 mL/min:
• Tungsten removal rates using the 10 parts APS + 0.4 parts Li periodate are stable for a period of several days when combined with alumina slurry.
• the pH was not adjusted, but stayed near-neutral, between pH 6.4 and 7.6, during the course of the test. Polishing was done used the Logitech PM5 polisher (33 rpm, 12" ICIOOO pad, 2 psig), 3" wafers (10,000 A sputtered W), 5%> alumina (50 parts of 10% alumina + 90% water slurry), and chemistry/slurry addition rate of 100 mL/min:
• a quantity of 500 ml of two comparative chemical solutions was each placed in a 600 ml beaker equipped with a magnetic stirring rod.
• the first ammonium persulfate solution consisted of 114 parts of ammonium persulfate in deionized water to give total of 1000 parts of solution having a pH of 3.1.
• the second ferric (III) nitrate solution consisted of 40 parts of ferric (III) nitrate nanohydrate dissolved in deionized water to give a total of 1000 parts of solution having a pH of 1.5.
• etch rates were: Ammonium persulfate 3000 A/min Ferric (III) nitrate 1287 A min
• ammonium hydroxide solution composed of 80 parts by weight of a 25 percent by weight aqueous ammonium hydroxide solution and 120 parts by weight of deionized water.
• the wafer was rinsed with deionized water and dried with nifrogen. The wafer was then weighed. A separate blank Ti wafer was etched in a 10 percent by weight H 2 O 2 solution to determine the amount of Cu on each 3 inch wafer. The results obtained are shown in the table below.
• CMP process results are based on hydroxylamine nitrate (HAN) and other hydroxylamine salts.
• HAN hydroxylamine nitrate
• other hydroxylamine salts Besides several examples with HAN, one example examines the use of citric acid in combination with HAN. Other combinations could include mono-, di- and tri- organic acids. Examples of such acids include, but are not limited to acetic acid, malonic acid and citric acid, respectively.
• Amines (and ammonia compounds) are more effective in neutral or basic solutions for polishing (etching) copper. Some ammonium compounds have only moderate success at polishing copper at low pHs. Hydrogen peroxide chemistries are usually used at low pHs. The following example shows that hydroxylamine nitrate (HAN, a mild oxidizing agent) will effectively polish copper. Hydroxylamine and its salts are not amines but do contain the NH2-group found in inorganic and organic amines. Hydroxylamine' s NH 2 group is attached to a hydroxyl (HO-group) which is not found in "amines" and does influence its oxidation-reduction potential.
• HO-group hydroxyl
• hydroxylamine nitrate chemistry is used in a slurriless polishing system.
• a Logitech PM5 polishing system (used for CMIP modeling experiments) was used with a Politex felt pad at 33 rpm with 2 psig pressure on the 3" copper wafer.
• the 5% chemistry (6.1 parts HAN with 95.9 parts water) was added to the polishing table at 50 mL/min.
• the removal rate was determined by a Four Dimensions four point probe used for determining metal film thickness on wafers. pH Removal Rate (A/min) 4.2 18 6.0 218
• the slurry concentration was 2.5% used with a Politex pad on the Logitech PM5 polisher at
• the hydrogen peroxide solution was composed of 15 parts of a 30% H 2 0 2 solution mixed with 85 parts of water. pH Removal Rate (A/min) 5% HAN 5 950+ 5% HAN 5 950+ 5% HAN 6 575+ 15%H 2 O 2 4 65 H 2 O 4.8 44
• Another feature is the selectivity of the polishing rate between different materials on the wafer. It is important that all materials (metals and the surrounding DDL layers) are not polished at the same rate, otherwise it would be difficult to stop at a specific layer.
• BPSG film In this example a 0.5 wt% hydroxylamine nitrate solution (0.6 parts of HAN in 99.4 parts water) is mixed with a 2.5% alumina slurry. The pH of the slurry varied between 4 and 4.4. The slurry mixture was used with a Politex pad on the Logitech PM5 polisher at 33 rpm with 2 psig pressure on the 3" copper wafer. The chemistry was added to the four point probe for determining metal film thickness on wafers, and the BPSG film thickness was determined by ellipsometer.
• the copper film removal rate was 637 A/min while the BPSG film was only polished at a 37 A/min rate.
• the selectivity of Cu to BPSG was 17.2. This means that the polishing process will "stop" when the BPSG layer is reached, since it has a much slower polishing rate.
• Another way to polish copper is to use a combination of chelating agents (polyfunctional organic acids) with the conjugate hydroxylamine salts.
• a solution of citric acid (8.8 parts citric acid adjusted with hydroxylamine to a pH 4.2 to 4.4, the remainder is water) is mixed with various concenfration of hydroxylamine (HDA) to obtain solutions with pHs close to neutral.
• HDA hydroxylamine
• These chemistries were used in a slurry polishing system.
• a Logitech PM 5 polishing system was used with a Politex felt pad at 33 rpm with 2 psig pressure on the 3" copper wafer. The chemistries were added to the polishing table between 20 to 90 mL/min. The removal rate was determined by a Four Dimensions four point probe for determining metal film thickness on wafers.
• Parts Citric Acid Sol Parts HDA pH Removal Rate (A/min) 100 0 4.2 58 95 5 6.6 64 90 10 954 80 20 7.0 1100
• compositions were made containing: hydroxylamine and/or hydroxylamine salts; benzotriazole; optionally added acid, such as sulfuric or nitric, to control pH; and DI water, as shown in the Table below.
• 82% HAN is 82 wt% hydroxylamine nitrate (NH 2 OH*HNO 3 ) in water; 50%.
• HDA® is 50 wt% hydroxylamine (NH 2 OH) in water; BTZ solution is 0.2 wt% benzotriazole in water; 25% TMAH is 25wt% tetramethylammonium hydroxide in water; and 15% IPHA is 15 wt% isopropylhydroxylamme in water.
• Comparative Example #1 as shown in the Table below, is commercially available from EKC Technologies, Inc., of Maynard, CA.
• Example #39 when using a 1 psi downforce, the composition exhibited an etch rate for TaN of about 200-400 A/min.
• the composition of Example 49 was used with a fixed pad, commercially available from 3M of St. Paul, MN (and with the following process conditions: -2 psi downforce; -70 RPM TS; -75 RPM CS; —175 mL/min flow rate; -4-15 second wash, e.g., for cleaning; and a temperature of about 70°F), it etched the layers of a Cu/TaN/Metal oxide substrate as follows: Cu: 118 A/min TaN: 580 A min MO: -0 A/min
• Example pH Avg TaN etch rate (lpsi pH Adjusted by using #38 -5.5 714 A/min HDA50 #40 -5.5 740 A/min TMAH #41 -5.5 770 A/min IPHA
• Example 41 containing IPHA
• Example 40 containing TMAH
• Example 38 containing HDA50

Applications Claiming Priority (2)

Publications (1)

Family

ID=34549837

Family Applications (1)

Country Status (3)

Cited By (6)

Families Citing this family (58)

Citations (3)

Family Cites Families (51)

• 2003
  • 2003-10-21 US US10/689,043 patent/US20040134873A1/en not_active Abandoned
• 2004
  • 2004-10-21 KR KR1020067009811A patent/KR20060126970A/ko not_active Application Discontinuation
  • 2004-10-21 WO PCT/US2004/034563 patent/WO2005042658A1/en active Application Filing

Patent Citations (3)

Also Published As

Similar Documents

Legal Events