CN1312745C - Preprocessing technique for removing oxide film from surface of copper seed crystal and reinforcing copper layer adhesion - Google Patents
Preprocessing technique for removing oxide film from surface of copper seed crystal and reinforcing copper layer adhesion Download PDFInfo
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- CN1312745C CN1312745C CNB2003101094544A CN200310109454A CN1312745C CN 1312745 C CN1312745 C CN 1312745C CN B2003101094544 A CNB2003101094544 A CN B2003101094544A CN 200310109454 A CN200310109454 A CN 200310109454A CN 1312745 C CN1312745 C CN 1312745C
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- copper
- seed crystal
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- crystal layer
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Abstract
In a copper interconnection technique, the surface oxidization of the seed crystal layer is a factor for affecting the quality of a copper coating layer and the stability of a copper interconnection line seriously. Currently, a method for eliminating CuO, some is easy to damage a seed crystal copper body; some easily cause seed crystal layer annealing, and a copper layer turns coarse to affect the quality of the copper coating layer. The present invention proposes a new technology for eliminating the oxidization film of the copper seed crystal layer and the forward process to the seed crystal layer. By applying and adjusting a negative current and a positive current and controlling the temperature of coating liquid and the rotary speed of a silicon chip, uses H ions in the coating liquid are used to eliminate the CuO on the surface of the seed crystal layer and protect the seed crystal layer body. The present invention can eliminate the CuO effectively without damaging a copper base and can enhance adhesive force between the coating layer and the seed crystal layer so as to reduce thermal stress inducing failure in copper wire distribution.
Description
Technical field
The invention belongs to integrated circuit (IC) chip manufacturing technology field, be specifically related to a kind of new method of removing copper seed layer surface film oxide and inculating crystal layer pre-treatment, to strengthen the adhesive force between coating and the inculating crystal layer, the thermal stress that alleviates in the copper wiring is induced inefficacy.
Background technology
The fast development of companion chip manufacturing technology, the principal element of restriction circuit speed becomes the RC that resistance (R) and the electric capacity (C) between line by line causes by grid delay (gate delay) and postpones.The resistivity of copper (1.7 μ Ω cm) is starkly lower than the aluminium (3.0 μ Ω cm) that tradition adopts, and selects for use copper to do line and can reduce connection resistances greatly; And application low k material replacement oxide layer is done the insulating barrier between line, then can reduce the electric capacity between line, and this just can effectively reduce RC and postpone the raising circuit speed.On the other hand, because line is more and more thinner, aluminum strip is subjected to the influence of electromigration effect more and more easily and forms cavity even fracture, have a strong impact on chip reliability, and the electric migration performance of copper is much better than aluminium, and this also is the main cause that it can replace aluminium.Therefore, up to the present, copper has become the interconnecting material of new generation of standard.
In traditional aluminium interconnection technique, the aluminum steel bar is formed by etching, and the aluminum steel of adjacent layer is connected by the tungsten in the through hole.Because copper is difficult to etching, adopted a kind of new method so copper is interconnected, be called ' Damascus ' (damascene) technology.Wherein, the ground floor metal adopts the technology with ' single Damascus ' (single damascene), and the above metal of the second layer adopts ' dual damascene ' technology (dual damascene), its concrete preparation method can be summarized as follows:
1. the young crystal layer deposit (PVD) of barrier layer and copper.The deposit of copper barrier layer and young crystal layer mainly comprises following 4 steps:
Degasification (degas);
Argon gas prerinse (Ar pre-clean);
Barrier layer deposition (barrier deposition);
Young crystal layer deposit (seed layer deposition).
2. copper is filled (plating)
3. copper polishes (CMP)
In the said method step, the deposit of copper seed layer is the needs for electro-coppering.Because its resistance is very high, is difficult in Direct Electroplating on the barrier layer, therefore need the young crystal layer of copper of pre-deposited one floor height conduction, for copper facing provides good grown layer, make electroplating process evenly carry out at silicon chip surface.In order to guarantee the quality of copper coating, need the good inculating crystal layer of preparation, except its thickness, uniformity and material structure composition were controlled in strictness, the oxidation of seed crystal surface was a factor that has a strong impact on copper coating quality and copper interconnecting line stability.
Press method flow, finish in the inculating crystal layer preparation, before the plating, silicon chip will wait for a period of time usually, have only the very easily oxidation in air of the thick inculating crystal layer of 15nm, its surface can form CuO, and this layer oxide-film can have a strong impact on the adhesion of copper coating and inculating crystal layer, make copper easier of thermal stress is induced and lost efficacy in the subsequent preparation method, reduce the product yield.Therefore need remove CuO by effective method, have two kinds through the method for attempting at present:
1, before the plating, silicon chip soaks a period of time in plating bath.Because plating bath is highly acid, utilizes following reaction can remove CuO:2H
++ CuO=Cu
2++ H
2O.This method is removed CuO easily, but is easy to damage the seed crystal copper layer, has and experimental results show that this method treatment effect is undesirable.
2, before the plating, in annealing furnace, feed H
2/ N
2Remove CuO, react and be: H
2+ CuO=Cu+H
2O.The shortcoming of this method is that the copper laminar surface of treated mistake is coarse, and expense is also high, and because reaction needed heats up, causes inculating crystal layer annealing easily, and the roughening of copper layer has a strong impact on quality of coating.
Summary of the invention
The pre-treating method that the objective of the invention is to propose a kind of effective removal seed crystal surface CuO and strengthen seed crystal and coating adhesive force.
Before the plating, if under the situation that power supply disconnects, silicon chip is immersed in the plating bath, because hydrogen (H
+/ H
2) the equilibrium potential E of redox couple
H+/H2Be higher than copper (Cu
2The equilibrium potential E of the redox couple of +/Cu)
Cu2+/Cu, thereby not only the CuO on copper surface can be corroded, the copper matrix also can be corroded, and considers that the copper seed layer of PVD deposit is not uniformly at the through hole of wiring or the thickness of groove, causes the local residual and local excessive erosion of CuO easily and damages copper.
The present invention is not making original hardware device on the basis of any change, by accurate regulation and control related electrode response parameter, can make that CuO is removed fully, and do not damage the inculating crystal layer body, simultaneously, can also between inculating crystal layer and normal coating, form excessively layer, effectively improve copper layer adhesive force.
The cathode-current density of existing copper electroplating method is generally: 1A/dm
2～6A/dm
2, negative electrode comprises following two reactions:
(1)Cu
2++2e＝Cu
(2)2H
++2e＝H
2
Wherein (2) are negative reaction, account for the seldom part (＜2%) of whole electric current, thereby the deposition efficiency of copper are very high.
The present invention makes cathode-current density be controlled at 0.5mA/dm by determining corresponding method parameter
2～30mA/dm
2In, and feed nitrogen, remove the oxygen in the plating bath, to prevent that copper is by oxidation again.This moment, negative electrode comprised following reaction:
(1)Cu
2++2e＝Cu
(2)2H
++2e＝H
2
(3)H
++CuO＝Cu
2++H
2O
Because electric current is very little, reaction (1), the speed of (2) is all very little, and the speed of (3) of reacting will be much larger than (1), and (2) so just can remove CuO fully, are adding under cathode current and the protection of nitrogen gas, and the inculating crystal layer body then can not be corroded.Simultaneously, because hydrogen (H
2/ H
+) evolution reaction and Cu
2+Be reduced to the polarizability difference of Cu reaction, under method controlled condition of the present invention, (1) and (2) speed is suitable, and the deposition speed of copper and efficient are all very low, so can not cause CuO to be embedded in result under the Cu layer.
Therefore, the present invention is after being immersed in silicon chip in the plating bath, and by applying cathode current, anode current, control bath temperature and silicon chip rotating speed rely on the H in the plating bath
+Remove the CuO of seed crystal surface, protection copper seed layer body.Reach better protection copper seed layer body by the size of adjusting the above-mentioned cathode current that applies.
The adjustable range of the cathode-current density that applies is 0.5mA/dm
2～30mA/dm
2, the above-mentioned anodic current density scope that applies is 10mA/dm
2～50mA/dm
2
The size adjustment process that applies cathode-current density is: it is .05mA/dm that the initial first step applies the cathode-current density scope
2～10mA/dm
2It is 5mA/dm that second step applied the cathode-current density scope
2～20mA/dm
2It is 10mA/dm that the 3rd step applied the cathode-current density scope
2～30mA/dm
2It is 50mA/dm that the 4th step applied the cathode-current density scope
2～100mA/dm
2, more than respectively go on foot the duration that cathode current applies and be 0.5S ~ 5S.
In the said process, whole process applies cathode current in the first step and the processing of the 4th step, does not apply anode current; In the second and the 3rd step, the ratio of the duration of cathode current and anode current is respectively: 9: 1, and 3: 1.
In the entire method process, the silicon chip rotating speed is: 30～50RPM; Temperature: 20～40 ℃, the wherein initial first step can be by applying nitrogen protection.
Benefit of the present invention also is, can form the transition zone of one deck densification between inculating crystal layer and copper coating, strengthens the adhesive force of copper layer and inculating crystal layer.Its principle is that under low current density density, the speed of growth of copper is very slow, makes the copper of separating out that the brilliant time of enough one-tenth be arranged, and material structure is relatively more perfect.
Description of drawings
Fig. 1 is the barrier layer, inculating crystal layer and oxide layer distribution schematic diagram.
Fig. 2 is the principle of electrochemical reaction schematic diagram.
Fig. 3 is a coating bath method structural representation.
Number in the figure: 1 is that TaN barrier layer, 2 is that Cu inculating crystal layer, 3 is that CuO, 4 is silicon substrate; 5 is that negative electrode, 6 is that anode, 7 is that plating bath, 8 is power supply; 9 is that negative electrode (silicon chip), 10 is that plating bath return port, 11 is that plating bath distribution plate, 12 is anode (phosphor-copper) for plating bath flows into groove, 13.
Embodiment
Implementation step of the present invention is as follows:
1, prepares barrier layer (barrier layer) by standard method, inculating crystal layer (seed layer).
2, silicon chip is immersed plating bath, add cathode-current density and be about 5mA/dm
2, the silicon chip rotation, rotating speed is: 40RPM, the duration is 2S, logical N
2Protection, temperature: 25 ℃
3, silicon chip adds cathode-current density and is about 10mA/dm
2, the duration is 1.8S, silicon chip adds anodic current density and is about 30mA/dm afterwards
2, the duration is 0.2S, the silicon chip rotation, and rotating speed is: 40RPM..Temperature: 25 ℃
4, silicon chip adds cathode-current density and is about 20mA/dm
2, the duration is 1.5S, silicon chip adds anodic current density and is about 30mA/dm afterwards
2, the duration is 0.5S, the silicon chip rotation, and rotating speed is: 40RPM.Temperature: 25 ℃
5, silicon chip adds cathode-current density and is about 75mA/dm
2, the duration is 2S, the silicon chip rotation, and rotating speed is: 40RPM.Temperature: 25 ℃
6, the normal copper method of filling of beginning.
Claims (3)
1, a kind of pre-treating method of removing the copper seed crystal copper oxide surface and strengthening copper layer adhesive force is characterized in that: by applying cathode-current density, anodic current density, control bath temperature and silicon chip rotating speed rely on the H in the plating bath
+Remove the CuO of seed crystal surface, protection copper seed layer body, wherein, the process that applies cathode-current density is: it is 0.5mA/dm that the initial first step applies the cathode-current density scope
2～10mA/dm
2It is 5mA/dm that second step applied the cathode-current density scope
2～20mA/dm
2It is 10mA/dm that the 3rd step applied the cathode-current density scope
2～30mA/dm
2It is 50mA/dm that the 4th step applied the cathode-current density scope
2～100mA/dm
2, more than respectively go on foot the duration that cathode-current density applies and be 0.5S ~ 5S; Wherein, whole process applies cathode current in the first step and the processing of the 4th step, does not apply anode current; In the second and the 3rd step, the ratio of the duration of cathode current and anode current is respectively: 9: 1, and 3: 1.
2, pre-treating method according to claim 1 is characterized in that: the silicon chip rotating speed is: 30～50RPM; Temperature: 20～40 ℃, the wherein initial first step applies nitrogen protection.
3, pre-treating method according to claim 1 is characterized in that: feed nitrogen in plating bath, to remove the oxygen in the plating bath.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2003101094544A CN1312745C (en) | 2003-12-16 | 2003-12-16 | Preprocessing technique for removing oxide film from surface of copper seed crystal and reinforcing copper layer adhesion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2003101094544A CN1312745C (en) | 2003-12-16 | 2003-12-16 | Preprocessing technique for removing oxide film from surface of copper seed crystal and reinforcing copper layer adhesion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1547245A CN1547245A (en) | 2004-11-17 |
| CN1312745C true CN1312745C (en) | 2007-04-25 |
Family
ID=34335207
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2003101094544A Expired - Fee Related CN1312745C (en) | 2003-12-16 | 2003-12-16 | Preprocessing technique for removing oxide film from surface of copper seed crystal and reinforcing copper layer adhesion |
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| Country | Link |
|---|---|
| CN (1) | CN1312745C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8193087B2 (en) | 2006-05-18 | 2012-06-05 | Taiwan Semiconductor Manufacturing Co., Ltd. | Process for improving copper line cap formation |
| CN101211818B (en) * | 2006-12-26 | 2010-04-07 | 中芯国际集成电路制造(上海)有限公司 | Semiconductor integrated circuit interlinkage structure interstitial copper-plating method and structure |
| CN112687610B (en) * | 2019-10-17 | 2023-03-24 | 中芯国际集成电路制造(北京)有限公司 | Interconnect structure and method of forming the same |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1116912A (en) * | 1997-06-25 | 1999-01-22 | Hitachi Ltd | Manufacture of semiconductor integrated circuit device and manufacture device of semiconductor integrated circuit device |
| US5939334A (en) * | 1997-05-22 | 1999-08-17 | Sharp Laboratories Of America, Inc. | System and method of selectively cleaning copper substrate surfaces, in-situ, to remove copper oxides |
| CN1226080A (en) * | 1998-02-12 | 1999-08-18 | 摩托罗拉公司 | Interconnect structure in semiconductor device and method of formation |
| US6423200B1 (en) * | 1999-09-30 | 2002-07-23 | Lam Research Corporation | Copper interconnect seed layer treatment methods and apparatuses for treating the same |
| CN1372313A (en) * | 2001-02-21 | 2002-10-02 | 日本电气株式会社 | Method for making semiconductor device |
| CN1419709A (en) * | 2000-03-21 | 2003-05-21 | 和光纯药工业株式会社 | Semiconductor wafer cleaning agent and cleaning method |
-
2003
- 2003-12-16 CN CNB2003101094544A patent/CN1312745C/en not_active Expired - Fee Related
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5939334A (en) * | 1997-05-22 | 1999-08-17 | Sharp Laboratories Of America, Inc. | System and method of selectively cleaning copper substrate surfaces, in-situ, to remove copper oxides |
| JPH1116912A (en) * | 1997-06-25 | 1999-01-22 | Hitachi Ltd | Manufacture of semiconductor integrated circuit device and manufacture device of semiconductor integrated circuit device |
| CN1226080A (en) * | 1998-02-12 | 1999-08-18 | 摩托罗拉公司 | Interconnect structure in semiconductor device and method of formation |
| US6423200B1 (en) * | 1999-09-30 | 2002-07-23 | Lam Research Corporation | Copper interconnect seed layer treatment methods and apparatuses for treating the same |
| CN1419709A (en) * | 2000-03-21 | 2003-05-21 | 和光纯药工业株式会社 | Semiconductor wafer cleaning agent and cleaning method |
| CN1372313A (en) * | 2001-02-21 | 2002-10-02 | 日本电气株式会社 | Method for making semiconductor device |
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| CN1547245A (en) | 2004-11-17 |
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