CN104120473B - The method of electro-coppering - Google Patents
The method of electro-coppering Download PDFInfo
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- CN104120473B CN104120473B CN201310145100.9A CN201310145100A CN104120473B CN 104120473 B CN104120473 B CN 104120473B CN 201310145100 A CN201310145100 A CN 201310145100A CN 104120473 B CN104120473 B CN 104120473B
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Abstract
A kind of method that the invention provides electro-coppering, it is applied in semiconductor fabrication sequence, electro-coppering process is divided into three phases, wafer rotating speed in first plating stage is above second and the 3rd wafer rotating speed of plating stage, and the wafer rotating speed of the 3rd plating stage is higher than the wafer rotating speed of the second plating stage.Use the present invention can improve the performance of copper electrodeposited coating.
Description
Technical field
The present invention relates to semiconductor device processing technology, particularly to a kind of method of electro-coppering.
Background technology
At present, in back segment (back-end-of-line, the BEOL) technique of semiconductor devices, can basis
Difference needs to grow multiple layer metal interconnection layer on a semiconductor substrate, and every layer of metal interconnecting layer includes that metal is mutual
Line and insulating barrier, this is accomplished by above-mentioned insulating barrier is manufactured groove (trench) and connecting hole, then
Filling metal in above-mentioned groove and connecting hole, the metal of filling is metal interconnecting wires, typically selects copper
As metal interconnecting wires material.
Prior art forms the method for metal interconnecting wires and comprises the following steps:
Step 11, by physical vapor deposition (PVD) method, on the bottom and sidewall of groove, even
Connecing on bottom and the sidewall in hole, sputtering forms barrier layer, such as by tantalum nitride (TaN) and tantalum (Ta)
The lamination barrier layer constituted.The above-mentioned lamination barrier layer being made up of TaN and Ta, simply one of which tool
Body embodiment, it is clear that also have the implementation method of multiple formation barrier film.
Step 12, on the surface on barrier layer, forms copper seed layer (seed layer) by the method for sputtering.
Step 13, by the method for electrochemistry plating (Electrical Chemical Plating, ECP) at copper
The surface of Seed Layer forms copper electrodeposited coating.In detail, as it is shown in figure 1, Fig. 1 is electroplating device schematic diagram.
Will be formed with the wafer of copper seed layer, insert in the electroplate liquid including copper ion of electroplating device, generally
Copper sulphate (CuSO4) etc., then wafer is connect negative electrode, electroplate liquid connects anode, and between a cathode and an anode
Energising, under electric field action, the inside on the surface of copper seed layer, i.e. groove and connecting hole, it is the formation of copper
Electrodeposited coating.
Step 14, carries out situ heat treatment to copper electrodeposited coating.
In prior art step 13 after electroplating process energising, the rotating speed of wafer remains at 125 turns every point
Clock (rpm), in order to control square resistance (Rs) uniformity of copper electrodeposited coating well, by manually adjusting
Wafer improves to the distance of electroplating device trench bottom, and distance is the nearest, and Rs uniformity is the highest.But due to firmly
The setting of part position, the space so adjusted is the most little, is also required to avoid adjusting excessively simultaneously, can to hardware
The wear damage that can cause.So how improve the performance of copper electrodeposited coating, become the problem that solution is presently required.
Summary of the invention
In view of this, present invention solves the technical problem that and be: how to improve the performance of copper electrodeposited coating.
For solving above-mentioned technical problem, technical scheme is specifically achieved in that
A kind of method of electro-coppering, is applied in semiconductor fabrication sequence, and electro-coppering process is divided into three phases,
Wafer rotating speed in first plating stage is higher than second with the 3rd wafer rotating speed of plating stage, and the 3rd plating
The wafer rotating speed in stage is higher than the wafer rotating speed of the second plating stage.
In the first plating stage, the rotating speed of wafer is 50～300rpm；
In the second plating stage, the rotating speed of wafer is 0～1rpm；
In the 3rd plating stage, the rotating speed 5～30rpm of wafer.
In the first plating stage, the rotating speed of wafer is 124～126rpm；
In the second plating stage, the rotating speed of wafer is 0rpm；
In the 3rd plating stage, the rotating speed 10～12rpm of wafer.
The time of described first plating stage is 10～15 seconds.
The time of described second plating stage is 2～10 seconds.
Described electro-coppering process is carried out on the test die, and described test wafer sequentially forms silica in advance
Basalis, barrier layer and copper seed layer.
The method farther includes: the copper electrodeposited coating formed in electroplating process is carried out situ heat treatment
Step.
As seen from the above technical solutions, electro-coppering process is divided into three phases to enter by the embodiment of the present invention
OK, second and the phase III use relatively low wafer rotating speed, keep solution interface layer between electroplate liquid and wafer
Thickness thicker, decrease the content of impurity in copper electrodeposited coating, thus be effectively improved copper electrodeposited coating square electricity
Resistance uniformity, effectively reduces copper electrodeposited coating internal stress, effectively reduces crystal column surface depression defect (pits
Defect) quantity, is finally reached the purpose improving copper electrodeposited coating performance.
Accompanying drawing explanation
Fig. 1 is electroplating device schematic diagram.
Fig. 2 is the method flow schematic diagram that the embodiment of the present invention improves copper electrodeposited coating performance.
Detailed description of the invention
For making the purpose of the present invention, technical scheme and advantage clearer, the most also
For embodiment, the present invention is described in more detail.
The present invention utilizes schematic diagram to be described in detail, when describing the embodiment of the present invention in detail, for the ease of
Illustrate, represent that the schematic diagram of structure can be disobeyed general ratio and be made partial enlargement, should be in this, as to this
Bright restriction, additionally, in actual making, should comprise the three dimensions chi of length, width and the degree of depth
Very little.
Copper electrodeposited coating described in the prior art is formed on product wafer, for the property of copper test electrodeposited coating
Can, the embodiment of the present invention improves the method for copper electrodeposited coating performance, carries out the most on the test die, flow process
Schematic diagram is as in figure 2 it is shown, it comprises the following steps:
Step 21, on the test die formation silica basalis.
Wherein, silica basalis uses chemical gaseous phase depositing process to be formed, and thickness is 8000～9000
Angstrom.
Step 22, silica substrate surface formed barrier layer.
Wherein, barrier layer uses physical gas-phase deposite method to be formed, and thickness is 200～300 angstroms, permissible
For tantalum nitride (TaN) layer or tantalum (Ta) layer, or the lamination barrier layer that TaN and Ta is constituted.
Step 23, barrier layer surface formed copper seed layer.
Wherein, copper seed layer is formed by physical gas-phase deposite method sputtering, and thickness is 900～1000 angstroms.
Step 24, divided by the method for ECP three phases copper seed layer surface formed copper electrodeposited coating.
Wherein, the thickness of copper electrodeposited coating is 7000～8000 angstroms.Concrete forming method is to will be formed with
The wafer of copper seed layer, inserts in the electroplate liquid including copper ion of electroplating device, generally copper sulphate
Deng, then wafer is connect negative electrode, electroplate liquid connects anode, and is energized between a cathode and an anode, at electric field
Under effect, the surface of copper seed layer, it is the formation of copper electrodeposited coating.
Embodiment of the present invention copper electrodeposited coating is divided into three phases to be formed, wherein the wafer in the first plating stage
Rotating speed is all far above second with the 3rd wafer rotating speed of plating stage, and the wafer rotating speed of the 3rd plating stage
The slightly above wafer rotating speed of the second plating stage.Specifically:
In the first plating stage, i.e. the initial period of electrical current, electric current is 0.5～2 ampere, makes wafer
Running up, the rotating speed of wafer is 50～300 rpms (rpm), and electroplating time is 10～15 seconds；Should
In plating stage, it is preferable that the rotating speed of wafer is 124～126rpm；
In the second plating stage, i.e. the stabilization sub stage of electrical current, electric current is 2～4 amperes, by wafer
Rotating speed is reduced to 0～1rpm, and electroplating time is 2～10 seconds；In this plating stage, it is preferable that wafer
Rotating speed is 0rpm；
In the 3rd plating stage, the formal plating stage of the biggest electric current, electric current is 15～20 amperes,
The rotating speed using wafer is 5～30rpm, owing to this stage is formal plating stage, and the thickness master of electrodeposited coating
To be formed in this stage, so the electroplating time in this stage can be according to the thickness of copper electrodeposited coating to be formed
It is adjusted flexibly.In this plating stage, it is preferable that the rotating speed of wafer is 10～12rpm.
Key to the invention is that and be divided into three phases to carry out electro-coppering process, and second and the phase III
Wafer rotating speed all ratios are relatively low, wherein, in the second plating stage, the rotating speed of wafer reduced to 0rpm, it is therefore an objective to
In order to thickness and the wafer of solution interface layer can be increased before the formal plating of big electric current as much as possible
The time reacted with solution interface layer and area, then in the phase III of strong-current electroplating, continue to use
The slow-speed of revolution 10～12rpm, has like this remained in that second stage metastable solution interface layer bar
Part.
The following detailed description of the relation between thickness and the copper electrodeposited coating performance of solution interface layer.
CuSO during plating4Electroplate liquid enters electroplating bath from the bottom of electroplating device, is full of whole electroplating bath,
Forming laminar flow when electroplate liquid and wafer contacts, the existence of laminar flow result in boundary layer between electroplate liquid and wafer
Generation.In boundary layer, organic additive (Additives) is mainly with diffusion (diffusion)
Mode is moved.And the rotary speed of wafer can affect the size of wafer and solution interface layer thickness, Jin Erying
Ring the diffusion motion of organic additive.Wherein, organic additive adds in electroplating solution, if
The organic additive contained in copper electrodeposited coating is the most, then mean that the impurity in copper electrodeposited coating is the most.
Formula: δ=1.61 ω-1/2r1/6D1/3, wherein, δ is the thickness of solution interface layer；ω is wafer
Rotary speed；R is viscosity, relevant with the structure of electroplating device；D is diffusion constant, with plating
Temperature is relevant.
According to above-mentioned formula, in electroplating temperature (affecting D) and electroplating device structure (affecting r)
Under conditions of Yi Ding, wafer rotary speed in electroplating process directly determines the thickness of solution interface layer.
Wafer rotary speed is the fastest, and solution interface layer is the thinnest；Otherwise, wafer rotary speed is the least, solution interface
Layer is the thickest, and organic additive is less susceptible to be diffused into the surface of wafer, participates in crystal column surface reaction grown
The fewest to the organic additive of crystal column surface, the impurity of crystal column surface is the fewest, so resistivity is the most just
The least.
On the other hand, for internal stress, when wafer rotary speed more hour, enter copper plating crystalline substance
The organic impurities of lattice is the fewest, and organic impurities has the effect of pinning to the motion of lattice.Crystal grain can be followed closely at impurity
The position pricked produces bigger internal stress, and impurity is the most, and internal stress is the biggest, finally from macro-stress
Show, i.e. rotating speed is the highest, and internal stress is the biggest, and rotating speed is the lowest, and internal stress is the least.
Furthermore, in the case of high-revolving, have more organic impurities to enter lattice, limit crystal grain
Growth so that before heat treatment, the crystal grain of high-revolving plating is more slow-revving little.In follow-up heat treatment
(anneal) during, crystal grain can slowly magnify, and annexes mutually, carries out secondary recrystallization, the longest
Become greatly bigger crystal grain.And the stage grown up at crystal grain, mutually annex, the cumulative volume of lattice reduces, from
And the generation of can be able to have vacant position in some region (Void).Initial grain is the least, when growing into big crystal grain,
The room produced will be the most.At high temperature, internal stress can promote room to assemble at crystal boundary, finally at crystalline substance
Circular surfaces forms pits defect.Nail and under the conditions of slow-revving, impurity is less on crystal boundary, to crystal boundary
Bundle effect is the most less, and crystal grain is relatively big, and in follow-up heat treatment process, the change of lattice cumulative volume is little, stays
Under room less, thus reduce the generation of pits defect.
So, second and the 3rd plating stage, use relatively low wafer rotating speed, be effectively improved copper
The performance of electrodeposited coating.
Step 25, copper electrodeposited coating being carried out situ heat treatment, heat treatment temperature is about 200 degrees Celsius.
So far, the method that the present invention improves copper electrodeposited coating performance is completed.
The preferred embodiment of the present invention is with in the first plating stage, and the rotating speed of wafer is 125rpm；Second plating rank
Duan Zhong, the rotating speed of wafer is 0rpm；In 3rd plating stage, as a example by the rotating speed of wafer is 12rpm,
After forming copper electrodeposited coating on test wafer, wafer is carried out testing electrical property, and uses SEM to see
Survey the form of surface defect, it is thus been found that the method using the electro-coppering of the present invention, the planted agent of copper electrodeposited coating
Power is remarkably decreased, the 400 of prior art MPas (MPa) drop to 340MPa；Square resistance uniformity
Significantly improving, dropped to 1.2 by the 2.3 of prior art, uniformity is the highest, and this value is the lowest；And scan and obtain
The pits defect quantity obtained also greatly reduces.On the other hand, by the method for the present invention, it has been greatly improved
The square resistance uniformity of copper electrodeposited coating, so after product uses a period of time, closing on preventative guarantor
Distance before supporting (PM), between fine setting wafer and electroplating device trench bottom, it is possible to realize square resistance
Significantly improving of uniformity.
The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all at this
Within the spirit of invention and principle, any modification, equivalent substitution and improvement etc. done, should be included in
Within the scope of protection of the invention.
Claims (7)
1. a method for electro-coppering, is applied in semiconductor fabrication sequence, it is characterised in that by electro-coppering
Process is divided into three phases, and the wafer rotating speed in the first plating stage is higher than second with the 3rd crystalline substance of plating stage
Circle rotating speed, and the wafer rotating speed of the 3rd plating stage is higher than the wafer rotating speed of the second plating stage, wherein, the
The wafer rotating speed of two plating stage is 0rpm.
2. the method for claim 1, it is characterised in that
In the first plating stage, the rotating speed of wafer is 50～300rpm；
In the 3rd plating stage, the rotating speed 5～30rpm of wafer.
3. method as claimed in claim 2, it is characterised in that
In the first plating stage, the rotating speed of wafer is 124～126rpm；
In the 3rd plating stage, the rotating speed 10～12rpm of wafer.
4. the method as described in claim 1,2 or 3, it is characterised in that described first plating stage time
Between be 10～15 seconds.
5. the method as described in claim 1,2 or 3, it is characterised in that described second plating stage time
Between be 2～10 seconds.
6. the method for claim 1, it is characterised in that described electro-coppering process is on the test die
Carry out, described test wafer sequentially forms silica basalis, barrier layer and copper seed layer in advance.
7. method as claimed in claim 6, it is characterised in that the method farther includes: will be in plating
During the copper electrodeposited coating that formed carry out the step of situ heat treatment.
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| CN104120473B true CN104120473B (en) | 2016-09-07 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105040059A (en) * | 2015-06-30 | 2015-11-11 | 苏州华日金菱机械有限公司 | Method for electroplating copper by using wafer device |
| CN107502935A (en) * | 2017-07-26 | 2017-12-22 | 武汉新芯集成电路制造有限公司 | A kind of method of electro-coppering |
| CN114959814A (en) * | 2022-06-09 | 2022-08-30 | 陕西众森电能科技有限公司 | Method for quickly electroplating high-conductivity and high-heat-conductivity copper layer |
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| US20030146102A1 (en) * | 2002-02-05 | 2003-08-07 | Applied Materials, Inc. | Method for forming copper interconnects |
| CN1480988A (en) * | 2002-07-25 | 2004-03-10 | ���µ�����ҵ��ʽ���� | Filming method of substrate and filming appts. |
| US20040231996A1 (en) * | 2003-05-20 | 2004-11-25 | Novellus Systems, Inc. | Electroplating using DC current interruption and variable rotation rate |
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| US20090283413A1 (en) * | 2008-05-13 | 2009-11-19 | Fujitsu Microelectronics Limited | Electrolytic plating method and semiconductor device manufacturing method |
| CN103077923A (en) * | 2013-01-14 | 2013-05-01 | 陆伟 | Copper electroplating method capable of avoiding holes |
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|---|---|---|---|---|
| US20030146102A1 (en) * | 2002-02-05 | 2003-08-07 | Applied Materials, Inc. | Method for forming copper interconnects |
| CN1480988A (en) * | 2002-07-25 | 2004-03-10 | ���µ�����ҵ��ʽ���� | Filming method of substrate and filming appts. |
| US20040231996A1 (en) * | 2003-05-20 | 2004-11-25 | Novellus Systems, Inc. | Electroplating using DC current interruption and variable rotation rate |
| CN101364542A (en) * | 2007-08-09 | 2009-02-11 | 中芯国际集成电路制造(上海)有限公司 | Copper plating method in semiconductor device |
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| CN103077923A (en) * | 2013-01-14 | 2013-05-01 | 陆伟 | Copper electroplating method capable of avoiding holes |
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