CN100423231C - Preparation method of nanometer heating electrode of phase-change storage - Google Patents
Preparation method of nanometer heating electrode of phase-change storage Download PDFInfo
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- CN100423231C CN100423231C CNB2005101111182A CN200510111118A CN100423231C CN 100423231 C CN100423231 C CN 100423231C CN B2005101111182 A CNB2005101111182 A CN B2005101111182A CN 200510111118 A CN200510111118 A CN 200510111118A CN 100423231 C CN100423231 C CN 100423231C
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Abstract
The present invention relates to a method for preparing a nanometer heating electrode for a phase-change memory. The annular nanometer heating electrode is formed by that firstly, a large-size hole is prepared on an SiO2 substrate by the technology of micro-nanometer processing; a layer of heating metal layer of a plurality of nanometers thick is then deposited in the hole and on the side wall of the hole by using the good step covering property of regular CVD technology, and a medium layer is filled into the hole; finally, medium materials and heating electrode materials at the upper end of the hole are polished by chemico-mechanical polishing. The present invention avoids the difficulty of filling the electrode materials and phase-change materials in small nanometer holes, and realizes the effect of a small-hole columnar heating electrode with the same area by using a greater annular nanometer heating electrode. The present invention is not only suitable for solving the problem of the nanometer heating electrode for the phase-change memory, and is also suitable for preparing the nanometer heating electrodes required by other electronic devices, especially nanometer electronic devices.
Description
Technical field
The present invention relates to a kind of method for preparing nanometer heating electrode of phase-change storage, specifically a kind of passing through prepares the ring-type nanometer heating electrode, thereby avoids the problem of nanometer aperture packing material difficulty, reaches nano-filled same heats.The preparation technology and the electrical characterization field that belong to nano material in the microelectronics.
Technical background
In present novel memory technology, phase transition storage (chalcogenide based RAM based on sulphur based semiconductor material, C-RAM) it is low to have a cost, speed is fast, the storage density height, make simple and with the current good outstanding advantage of CMOS (complementary metal-oxide-semiconductor) ic process compatibility, be subjected to worldwide extensive concern.In addition, C-RAM has performances such as anti-irradiation (ability of resistant to total dose is greater than 1Mrad (Si)), high-low temperature resistant (55-125 ℃), against violent vibration are moving, anti-electronic jamming, in national defence and aerospace field important application prospects is arranged.From 2003, international semiconductor TIA thinks that always phase transition storage most possibly replaces present SRAM (static RAM), current main products such as DRAM (dynamic random access memory) and FLASH memory (flash memory) and become the semiconductor storage unit of future generation of following memory main product, USA space council delivers statement recently: think: the C-RAM technology is the breakthrough of the highly reliable computer chip material of high safety, the research of this memory technology provides unprecedented guarantee for war with computer chip, and this technology may cause the change of the revolution of computer.
Main in the world electronics and semiconductor company all is being devoted to the development of C-RAM at present.There are Ovonyx, Intel, Samsung, IBM, Bayer, ST Micron, AMD, Panasonic, Sony, Philips, British Areospace, Hitachi and Macronix etc. in main research unit.In May, 2005, American I BM, German Infineon science and technology, Taiwan Macronix International (Macronix International) are announced joint study exploitation phase transition storage, send 20～25 technical staff to participate in this research specially.3 companies provide the technology of being good at separately to study respectively, specifically, exactly with the relevant material that IBM is had and the basic research ability of physical characteristic, the research of the various internal memory products that Infineon has, exploitation and volume production technical capability, and the non-voltile memory technical capability of Macronix International is integrated in this research.
Present situation at present C-RAM fast development, want to realize as early as possible its practicability, industrialization, reach the target of " faster, littler, colder ", the C-RAM device size must further dwindle, in the device phase-change material undergo phase transition the zone size and heating electrode size further dwindle, reach deep-submicron so that nanometer scale, undergo phase transition required current/voltage, reduce the power consumption of phase-changing memory unit thereby reduce the sulphur based material.
As prepare at present more than the method for phase transition storage is to utilize the method for various etchings to prepare small holes, fills phase-change material or electrode material then.For example utilize the focused-ion-beam lithography technology on dielectric layer, to prepare the nanometer aperture, in aperture, fill heating electrode material (as W, Pt etc.) with the method for magnetron sputtering W then, form nano-electrode through polishing again.But when the diameter of aperture when 200nm is following, fill relatively difficulty of W or other heating material therein, materials such as W often just are deposited in the aperture, are difficult to enter in the hole, have a lot of cavities in the hole, cause loose contact even open circuit.In addition, utilize focused-ion-beam lithography technology perforating efficiency lower, expense is than higher.The present invention is exactly at along with constantly the reducing of phase transition storage volume, and how to realize the reducing nanometer heating electrode area and increases the integrity problem of electrode and a kind of simple, the practical new that proposes.
Summary of the invention
The invention provides a kind of method for preparing nanometer heating electrode of phase-change storage.Fill the difficulty of metal material (W, Pt) etc., a kind of method for preparing the ring-type nanometer heating electrode of proposition at present nano aperture.At first, SiO is arranged in length by the micro-nano process technology
2Or on the substrate of other medium the preparation large-size hole, then utilize the heating of metal layer (W, Pt etc. have the metal material of certain resistivity) of common CVD technology several nanometers of deposit one deck in this hole, and then in hole the filled media layer, carry out chemico-mechanical polishing (CMP) at last, thereby form ring-type nano-electrode one by one.The present invention utilizes larger-diameter ring-type heating electrode to realize having the effect than the column heating electrode of minor diameter of same area, avoided the difficulty of the filling electrode material of small size nano aperture, the present invention simultaneously not only is applicable to the nanometer heating electrode of phase-change storage problem that solves, be equally applicable to the particularly preparation of the required nanometer heating electrode of nanometer electronic device of other electronic device, have great practical value.Main technique step of the present invention is as follows:
(a) utilize high vacuum magnetically controlled sputter method deposit one deck hearth electrode on Si substrate or other substrate, the thick SiO of in-situ sputtering growth 50nm-500nm on hearth electrode
2Or SiN
xDielectric layer;
(b) utilize electron beam lithography technology or other lithographic technique to prepare the nano aperture array on above-mentioned dielectric layer, the diameter of hole is at 300nm-600nm, and the bottom of hole links to each other with hearth electrode;
(c) utilizing CVD technology heating electrode material about deposition thickness 10nm in the aperture that step (b) is made is metal W or Pt, and the reacting gas that uses during deposition is WF
6, SiH
4And H
2Mist, the volume ratio of three kinds of gases is 2: 1: 1;
(d) in deposit fill SiO in the aperture of metal
2, SiN
xDeng dielectric material, fill up whole hole;
(e) adopt chemico-mechanical polishing (CMP) technology, the dielectric material (SiO that aperture is outer
2Or SiN
xDeng) and metal material (W) removal, obtaining ring-type nano-electrode array, the external diameter of ring-type nano-electrode and the difference of internal diameter are 10nm-20nm;
(f) on the above-mentioned substrate that has a ring-type nano-electrode array, prepare phase-change material, heat-insulating material and upper electrode material, by peeling off or the method for etching forms the phase transformation memory device unit array;
(g) above-mentioned phase transformation memory device unit with ring-type nanometer heating electrode is connected in the electrical measurement system, carry out the writing of phase transformation memory device unit, wiping, read operation, study its storage characteristics and fatigue properties, study its current-voltage (I-V) characteristic, resistance-stream (R-I) characteristic, electric current-time (I-t) characteristic etc., phase change current is less than 0.1mA, and resistance differs one more than the magnitude before and after the phase transformation.
Described backing material is unrestricted, can be the Si sheet of using always, and semi-conducting materials such as GaAs also can be dielectric material or metal materials such as quartz glass, ceramic substrate.
Described hearth electrode is unrestricted, can be conductor material commonly used such as aluminium, copper, and its thickness is 200-400nm.
Described dielectric material is SiO commonly used
2, SiN
xDeng material, thickness 50nm-500nm.
Hole on the described dielectric layer can use methods such as electron beam photoetching process, focused-ion-beam lithography method, electron beam exposure and reactive ion etching method to obtain.
The material of described heating electrode is the material that W, Pt etc. have certain resistivity, even can deposit heating material such as TiW, the TiAlN etc. of the high resistivity of the several nanometer thickness of one deck again on W, Pt etc., thereby improves heats, reduces operating current.
The surface smoothness of the ring-type nano-electrode that obtains after the described chemico-mechanical polishing (CMP) is very high, even can reach nanoscale, does not influence follow-up long membrane process.
Described stripping means is to have substrate surface coating one deck photoresist of ring-type nano-electrode earlier, then by exposing the ring-type nano-electrode after the cloudy reticle exposure, there is photoresist in other place, with acetone photoresist is together removed together with the material on the photoresist after having grown layers of material, last only phase-change material, heat-insulating material and the top electrode of remaining electrode zone form the phase transformation memory device unit array.
The method of described etching is after having grown phase-change material, heat-insulating material and top electrode on the substrate that has the ring-type nano-electrode; protected by photoresist by whirl coating, the sunlight ring-type nano-electrode zone, exposure back of cutting blocks for printing; utilize reactive ion etching or other lithographic method to remove ring-type nano-electrode material in addition then, form phase transformation memory device unit.
The overlapping area of described ring-type nano-electrode and phase-change material can change between minimum value and maximum, minimum value when not overlapping 0, the area of maximum ring-type nano-electrode when overlapping fully itself, thus the required electric current of phase transformation also changes along with the variation of overlapping area.
The invention provides a kind of preparation method of simple, practical nanometer heating electrode of phase-change storage, the present invention is equally applicable to other device that need use nano-electrode.
Description of drawings
Deposit and the cross-sectional view of filling heating electrode material and dielectric material successively in Fig. 1 hole;
Fig. 2 carries out structure shown in Figure 1 the cross-sectional view that obtains after the chemico-mechanical polishing (CMP).
The cross-sectional view of Fig. 3 behind sputter phase-change material on the substrate surface that has the ring-type nano-electrode after the polishing
Fig. 4 through peel off or the etching phase-change material after the structural representation that obtains.
The structural representation of Fig. 5 after covering layer of insulation material on the structure of Fig. 4.
Fig. 6 carves the heat-insulating material that removes on the phase-change material, as the fairlead of top electrode.
Fig. 7 is the deposition of electrode material in the hole, carves the electrode material except that the hole, thereby obtains the phase transformation memory device unit array.
The phase transformation memory device unit array that Fig. 8 phase-change material and ring-type nano-electrode have only part to overlap.
1. dielectric layers among the figure; 2. hearth electrode; 3. heat insulation layer; 4. heating electrode; 5. phase-change material; 6. top electrode.
Embodiment
Below by specific embodiment, further illustrate substantive distinguishing features of the present invention and obvious improvement, but the present invention only is confined to described embodiment by no means.
Embodiment 1:
(1) the thick SiO of heat growth 100nm on the Si substrate
2Or utilize PECVD (plasma enhanced chemical vapor deposition) to prepare the thick SiN of 100nm
xDeielectric-coating is then at SiO
2Or SiN
xOn utilize the method for magnetron sputtering or evaporation to prepare the thick Al film of one deck 80nm as hearth electrode;
(2) utilize the method for PECVD or sputter on hearth electrode Al film, to prepare the thick SiO of 300nm-500nm
2, PECVD prepares SiO
2The source be TEOS (tetraethoxysilane);
(3) at the thick SiO of above-mentioned 300nm-500nm
2On utilize the electron beam lithography technology to prepare nano aperture, hole bottom links to each other with hearth electrode, hole diameter is in the 300nm-600nm scope; (Fig. 1)
(4) utilize CVD technology deposit W film in hole, reaction source is WF
6, SiH
4And H
2The three was by 2: 1: 1; The mixture of volume ratio, the about 5-10nm of thickness; Utilize CVD or sputtering method in hole, to fill SiO
2Or SiN
xDielectric material fills up until hole;
(5) utilize chemical Mechanical Polishing Technique (CMP) to throw and remove W, the SiO of hole with exterior domain
2Or SiNx dielectric material; (Fig. 2)
(6) magnetron sputtering phase-change material GeSbTe, the about 80nm of thickness, base vacuum are 3 * 10
-6Torr, the sputter vacuum is 0.08Pa, power 100W; (Fig. 3)
(7) utilization is peeled off with lithographic technique and is prepared phase change material unit (Fig. 4) and top electrode (Fig. 6), thereby obtains phase transformation memory device unit; (Fig. 7)
(8) this phase transformation memory device unit is connected in the electrical measurement system, carries out the writing of phase transformation memory device unit, wiping, read operation, study its storage characteristics and fatigue properties etc.
Embodiment 2:
The 1st of embodiment 1 go on foot the 6th the step finish after, utilization is peeled off with lithographic technique and is prepared the phase transformation memory device unit (Fig. 8) that phase-change material and ring-type nano-electrode have only part to overlap, and the phase change current of such phase transformation memory device unit can further reduce.
Embodiment 3:
Change the substrate of embodiment 1 into metal substrate, as Al, Au etc., other (2) with embodiment 1-(8) step can obtain result similar to Example 1.
Embodiment 4:
Change the substrate of embodiment 1 into pottery, quartz or other insulative material substrate, sputter thereon prepares the thick SiO of 100nm
2Or utilizing PECVD to prepare the thick SiNx deielectric-coating of 100nm, other can obtain result similar to Example 1 with embodiment 1.
Embodiment 5:
After utilizing the method deposit W film of CVD in embodiment 1 the 4th step, then prepare the several nanometer thickness of one deck again and have more heating material such as TiW, the TiAlN etc. of high resistivity, and then the filled media material.Other step is with embodiment one.Can obtain better heating effect like this, reduce the operating current of device.
Claims (10)
1. method for preparing nanometer heating electrode of phase-change storage is characterized in that:
(a) preparation-metal level prepares one deck dielectric layer then as hearth electrode on substrate, utilizes the micro-nano process technology to prepare the hole array at last on dielectric layer; The bottom of hole links to each other with hearth electrode;
(b) at hole sidewall and bottom deposit one deck heating electrode material;
(c) filled media material in the hole of step (b) deposit heating electrode material;
(d) utilize dielectric material and the heating electrode material of chemico-mechanical polishing throwing except that hole, thereby on substrate, form ring-type nano-electrode array;
(e) on the above-mentioned substrate that has a ring-type nano-electrode array, prepare phase-change material, heat-insulating material and upper electrode material, by peeling off or the method for etching forms the phase transformation memory device unit array.
2. by the described a kind of method for preparing nanometer heating electrode of phase-change storage of claim 1, it is characterized in that in described backing material Si sheet, GaAs semi-conducting material, quartz glass and the ceramic substrate any one.
3. by the described a kind of method for preparing nanometer heating electrode of phase-change storage of claim 1, it is characterized in that described hearth electrode is aluminium or copper, thickness is 200-400nm.
4. by the described a kind of method for preparing nanometer heating electrode of phase-change storage of claim 1, it is characterized in that dielectric material is SiO
2Or the SiNx material, thickness 50nm-500nm.
5. by the described a kind of method for preparing nanometer heating electrode of phase-change storage of claim 1, it is characterized in that the hole on the described dielectric layer obtains with any one method in electron beam photoetching process, focused-ion-beam lithography method, electron beam exposure and the reactive ion etching method, the diameter of hole is 300-600nm.
6. by the described a kind of method for preparing the phase transition storage nano-electrode of claim 1, it is characterized in that the material of heating electrode is W or Pt with CVD method deposition, reacting gas is WF during deposition W
6, SH
4And H
2Mist, three's volume ratio are 2: 1: 1.
7. by the described a kind of method for preparing the phase transition storage nano-electrode of claim 1, the surface smoothness that it is characterized in that the ring-type nano-electrode that obtains after the chemico-mechanical polishing reaches nanometer scale, and the external diameter of ring-type nano-electrode and the difference of internal diameter are 10nm-20nm.
8. by the described a kind of method for preparing nanometer heating electrode of phase-change storage of claim 1, the step (e) that it is characterized in that forming by the method peeled off phase transformation memory device unit is to have substrate surface coating one deck photoresist of ring-type nano-electrode earlier, then by exposing the ring-type nano-electrode after the cloudy reticle exposure, there is photoresist in other place, preparation has phase-change material on substrate, heat-insulating material and upper electrode material, having grown the back together removes photoresist together with the material on the photoresist with acetone, the last only phase-change material of remaining electrode zone, heat-insulating material and top electrode form the phase transformation memory device unit array.
9. by the described a kind of method for preparing nanometer heating electrode of phase-change storage of claim 1; the method that it is characterized in that described etching is after having grown phase-change material, heat-insulating material and top electrode on the substrate that has the ring-type nano-electrode; protected by photoresist by whirl coating, the sunlight ring-type nano-electrode zone, exposure back of cutting blocks for printing; utilize reactive ion etching or other lithographic method to remove ring-type nano-electrode material in addition then, form the phase transformation memory device unit array.
10. by the described a kind of method for preparing nanometer heating electrode of phase-change storage of claim 1, the overlapping area that it is characterized in that described ring-type nano-electrode and phase-change material changes between minimum value and maximum, minimum value when not overlapping 0, the area of maximum ring-type nano-electrode when overlapping fully itself, thus the required electric current of phase transformation also changes along with the variation of overlapping area.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101859871A (en) * | 2009-04-02 | 2010-10-13 | 索尼公司 | Memory element and manufacture method thereof and semiconductor storage |
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| TWI426604B (en) | 2008-06-03 | 2014-02-11 | Higgs Opl Capital Llc | Phase-change memory devices and methods for fabricating the same |
| CN101335327B (en) * | 2008-08-05 | 2010-06-16 | 中国科学院上海微系统与信息技术研究所 | Method for controlling phase-change material or phase-change memory unit volume change and corresponding construction |
| KR101429724B1 (en) * | 2008-12-10 | 2014-08-13 | 삼성전자주식회사 | Method of forming a contact structure, method of fabricating a semiconductor device using the same, and semiconductor devices fabricated using the same |
| CN102412367B (en) * | 2010-09-19 | 2013-08-14 | 中芯国际集成电路制造(上海)有限公司 | Fabrication method of bottom electrode of phase change memory (PCM) |
| CN102664236B (en) * | 2012-05-16 | 2014-09-10 | 中国科学院上海微系统与信息技术研究所 | Ring electrode structure for low-power-consumption phase change memory and preparation method |
| US9627613B2 (en) * | 2015-03-20 | 2017-04-18 | Taiwan Semiconductor Manufacturing Co., Ltd. | Resistive random access memory (RRAM) cell with a composite capping layer |
| CN112635667B (en) * | 2020-12-30 | 2022-11-25 | 上海集成电路装备材料产业创新中心有限公司 | Phase change memory unit and preparation method thereof |
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