US20080029402A1

US20080029402A1 - Electrochemical processing apparatus and method of processing a semiconductor device

Info

Publication number: US20080029402A1
Application number: US11/882,177
Authority: US
Inventors: Tetsuya Kurokawa; Koji Arita; Kaori Noda
Original assignee: NEC Electronics Corp
Current assignee: Renesas Electronics Corp
Priority date: 2006-08-07
Filing date: 2007-07-31
Publication date: 2008-02-07
Also published as: JP4819612B2; JP2008038208A; CN101144177A

Abstract

An electrochemical processing apparatus is provided, in which a substrate and an anode placed in a chamber are partitioned into a cathode region including the substrate and an anode region including the anode by placing a multi-layered structure of a filtration film and a cation exchange film so that the filtration film is positioned on the substrate side. A plating solution containing additives is introduced into the cathode region, whereby a substrate is plated.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to an electrochemical processing apparatus and a method of processing a semiconductor device.
2. Description of the Related Art
Electrochemical processing is generally used for embedding recesses such as trenches and through holes formed on or over a semiconductor substrate with a metal material such as copper to form wiring and vias. Conventionally, such electrochemical processing has problems that particles are generated on an anode side in a plating solution, and additives such as an accelerator, a leveler, and a suppressor are decomposed on the anode. In order to prevent such problems, there are some technologies that an ion exchange film or a filtration film separating between an anode and a substrate is used in an electrochemical processing apparatus.
JP 2003-73889 A describes the configuration in which a chamber is partitioned into a cathode region and an anode region with an anion exchange film when copper is electro-plated on or over a semiconductor wafer. This configuration is considered to be capable of preventing particles from adhering to the semiconductor wafer.
JP 2005-133187 A describes a plating technique that an ion exchange film and a surface of a substrate to be plated are brought close or contacted with each other and moved relatively. Since plating on an upper portion of a wiring pattern is suppressed to be low plating speed, this is considered to be capable of forming a flat electro-plated film.
JP 2000-192298 A describes the configuration in which a partition film made of a porous filtration film or a cation exchange film is placed between anode electrode plate and a substrate to be plated, whereby a chamber body is partitioned into an anode chamber and a cathode chamber. This prevents additives in a plating solution from coming into contact with the surface of an anode electrode plate to be decomposed, thereby suppressing a plated surface from becoming coarse due to the shortage of additives, and can remove oxygen gas generated on the surface of the anode electrode plate rapidly, thereby forming an uniform metal electro-plated film.
JP 2001-49498 A describes the configuration in which a substrate to be plated and an anode electrode are partitioned by placing an ion exchange resin or a porous filtration film therebetween. This configuration is considered to be capable of preventing air bubbles from adhering to a plated surface of the substrate to be plated.
However, the inventors of the present invention found that there are the following problems in performing plating with the use of these techniques.
A cation exchange film that selectively transmits only cations is generally composed of a sulfonic group or the like, and the surface thereof is negatively charged. Therefore, in the case where a cation exchange film is provided between an anode and a substrate, when additives are neutral or negatively charged, the cation exchange film can suppress the additives from being transmitted. However, in the case where the additives are positively charged, the additives are likely to adsorb to the cation exchange film. In general, when a leveler is positively charged, and a cation exchange film is used, the consumption rate of the leveler becomes high.
Furthermore, in the case where a filtration film is provided between an anode and a substrate, when a filtration diameter of the filtration film is set to be too minute, the transmission of ions that are required to be transmitted between an anode side and a substrate side is also prevented. Therefore, the filtration diameter cannot be set to be so minute. For example, in the case of using a dissoluble copper anode as an anode, if copper ions do not move smoothly between the anode and the substrate, the use efficiency of the copper ions from anode decreases. Therefore, it is necessary to increase the filtration diameter of the filtration film to such a degree that the copper ions can be transmitted. Therefore, the transmission of the additives with a small molecular weight such as an accelerator cannot be suppressed.
In the above-mentioned conventional technique, since only either one of a cation exchange film or a filtration film (or an anion exchange film) is provided between an anode and a substrate, the consumption of additives in a plating solution cannot be reduced. Furthermore, the additives are transmitted to the anode side, come into contact with the anode to be decomposed, and are accumulated in the plating solution as impurities, which cause the defects in an electro-plated film.

SUMMARY

According to the present invention, there is provided an electrochemical processing apparatus, including:
a chamber; and
a multi-layered structure including a filtration film and a cation exchange film,
the multi-layered structure being placed between a substrate and an anode that are placed in the chamber so that the filtration film is positioned on the substrate side and partitioning the chamber into a cathode region including the substrate and an anode region including the anode.
According to the present invention, there is provided a method of processing a semiconductor device, including an electrochemical processing step of plating a substrate in a state where a multi-layered structure including a filtration film and a cation exchange film is placed between a substrate and an anode that are placed in a chamber so that the filtration film is positioned on the substrate side, and the chamber is partitioned into a cathode region including the substrate and an anode region including the anode. A plating solution containing additives is used in the electrochemical processing step.
Herein, the filtration film can be a nonpolar filtration film having no polarity. Furthermore, the filtration film can be configured so as to have a porous structure and suppress the transmission of molecules with a large molecular weight (molecular diameter) by adjusting a hole diameter.
With such a configuration, for example, even in the case where a leveler, an accelerator, and a suppressor that are additives are present in a cathode region, the leveler can be prevented from adsorbing to a cation exchange film, and the additives with a small molecular weight can be prevented from being transmitted to an anode side. This can reduce the consumption of the additives.
The anode (anode electrode plate) can also be composed of, for example, a dissoluble copper anode, or an insoluble anode. In the case where the anode is composed of a copper anode, a multi-layered film can be configured so as to transmit copper ions.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, advantages and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view illustrating a configuration of an electrochemical processing apparatus of the present invention;

FIG. 2 is a plan view in which a multi-layered structure included in the electrochemical processing apparatus of the present invention is seen from the filtration film side;

FIG. 3 is a view illustrating the consumption of a leveler in an example;

FIG. 4 is a diagram illustrating the consumption of an accelerator in the example;

FIG. 5 is a diagram illustrating the consumption of a suppressor in the example; and

FIGS. 6A and 6B are cross-sectional views illustrating a process of a semiconductor device of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The invention will be now described herein with reference to illustrative embodiments. Those skilled in the art will recognize that many alternative embodiments can be accomplished using the teachings of the present invention and that the invention is not limited to the embodiments illustrated for explanatory purposes.
FIG. 1 is a cross-sectional view illustrating a configuration of an electrochemical processing apparatus 200 in the present embodiment.
The electrochemical processing apparatus 200 includes a chamber 201, and an anode 220 placed in the chamber 201. In the present embodiment, the anode 220 can be composed of a dissoluble copper anode. In the chamber 201, a plating solution 202 is contained. The plating solution 202 is composed of, for example, copper sulfate aqueous solution. In addition, the electrochemical processing apparatus 200 has a substrate support (not shown) on which a substrate 100 is to be placed, and the substrate 100 is placed on the substrate support.
The electrochemical processing apparatus 200 includes a multi-layered structure 204 of a filtration film 210 and a cation exchange film 208 placed between the substrate 100 and the anode 220. The multi-layered structure 204 is placed so that the filtration film 210 is positioned on the substrate 100 side. The chamber 201 is partitioned into a cathode region 202 a including the substrate 100 and an anode region 202 b including the anode 220 by the multi-layered structure 204. Furthermore, the electrochemical processing apparatus 200 includes a diffusion plate 214 placed between the multi-layered structure 204 and the substrate 100. The diffusion plate 214 is placed for the purpose of making the flow of the plating solution 202 uniform in the vicinity of the substrate 100. It should be noted that the diffusion plate 214 is configured so as to have a sufficiently large hole diameter and to transmit components of the plating solution 202.
In the cathode region 202 a, levelers, accelerators, and suppressors are introduced as additives into the plating solution 202.
In the present embodiment, as the levelers, for example, a positively charged material having a molecular weight of 2000 to 3000 can be used. As such a material, for example, a cationic amine polymer can be used.
In the present embodiment, as the accelerators, for example, a negatively charged material having a molecular weight of 500 or less and a disulfide bond can be used. As such a material, the one represented by the general formula: SO₃—R₁—S—S—R₂—SO₃— (herein, R₁and R₂are respectively hydrocarbon chains independently) can be used.
In the present embodiment, as the suppressors, for example, a material having a molecular weight of 2000 to 3000 and no polarity can be used. As such a material, for example, polyethylene glycol can be used.
The multi-layered structure 204 is configured so as to suppress the transmission of levelers, accelerators, and suppressors. Furthermore, in the present embodiment, the multi-layered structure 204 is configured so as to transmit copper ions. The filtration film 210 has minute holes, and transmits molecules with a size smaller than the hole diameter and suppresses the transmission of molecules with a size larger than the hole diameter. The filtration film 210 is configured so as to have no polarity and have a hole diameter of suppressing the transmission of at least the levelers. In the present embodiment, the hole diameter of the filtration film 210 can be set to be 0.5 μm or less. This can suppress the transmission of the levelers. On the other hand, in order to transmit copper ions, the hole diameter of the filtration film 210 can be set to be 0.01 μm or more. As the filtration film 210, for example, polypropylene can be used.
The cation exchange film 208 selectively transmits only cations. As the cation exchange film 208, for example, polyacrylic resin having a sulfonic group can be used.
In the present embodiment, the multi-layered structure 204 includes a multi-layered film 206 in which the filtration film 210 and the cation exchange film 208 are provided in contact with each other, and a support plate 212 supporting the multi-layered film 206. By using the multi-layered film 206, bubbles of air or the like can be prevented from entering between the filtration film 210 and the cation exchange film 208, and the flow of the plating solution in the chamber 201 can be regulated easily.
FIG. 2 is a plan view in which the multi-layered structure 204 is seen from the filtration film 210 side. The chamber 201 is configured in a cylindrical shape (not shown). The multi-layered structure 204 is configured in a size equal to that of the cross-section of the chamber 201, and partitions the chamber 201 into the cathode region 202 a and the anode region 202 b. The multi-layered structure 204 can have any configuration as long as levelers, accelerators, and suppressors introduced in the cathode region 202 a are not transmitted to the anode region 202 b. As other examples, a partition wall that partially partitions the plating solution 202 and the substrate 100 is provided, and the multi-layered structure 204 may be placed in an open portion which is not partitioned by the partition wall. Herein, the support plate 212 is composed of, for example, a plastic material, and has a framework reinforcing the multi-layered film 206.
Next, the function of the multi-layered structure 204 configured as described above will be described.
In the multi-layered structure 204, the filtration film 210 is provided on the cathode region 202 a side. Therefore, in the case where levelers, accelerators, and suppressors are introduced in the cathode region 202 a, first, the transmission of levelers and suppressors having a large molecular weight are suppressed by the filtration film 210. This can prevent levelers and suppressors from moving to the anode region 202 b, thereby reducing the consumption thereof. Furthermore, the positively charged levelers can be prevented from coming into contact with the cation exchange film 208, so the consumption of levelers can be reduced more. On the other hand, even when accelerators having a small molecular weight are transmitted through the filtration film 210, the cation exchange film 208 can prevent accelerators from moving to the anode region 202 b. Consequently, even when the hole diameter of the filtration film 210 is set in such a degree as to transmit accelerators, the consumption of accelerators can be reduced.
Next, the procedure of processing a semiconductor device using the electrochemical processing apparatus 200 in the present embodiment will be described with reference to FIG. 6. A semiconductor device 300 is formed on a semiconductor substrate 302, including transistors and the like, an insulating film 304 formed over the transistors, and an insulating film 306 formed over the insulating film 304. Wiring and vias are formed in the insulating films 304 and 306.
In the semiconductor device 300 thus configured, interconnect features (trenches) are formed on the insulating film 306. Herein, as shown, in the insulating film 306, interconnect feature 308, interconnect feature 310, interconnect feature 312, interconnect feature 314, interconnect feature 316, interconnect feature 318, and interconnect feature 320 are formed (FIG. 6A).
The procedure of burying such trenches with a wiring material will be shown below. First, a barrier metal film is formed in the trenches of the insulating film 306. TaN/Ta is usually used as a barrier metal of copper interconnects. Then a seed film for plating is formed on the barrier film. Herein, a seed film is made of a copper film formed by CVD or the like.
Then, the substrate with the seed film formed thereon is plated using the electrochemical processing apparatus 200. Consequently, an electro-plated film 332 is formed in the trenches. Herein, the electro-plated film 332 is, for example, made of a copper film (FIG. 6B). The defects caused by a decomposition product of the additives are suppressed by using the electrochemical processing apparatus 200 in the present embodiment.

EXAMPLE

In the same way as in the configuration of the apparatus illustrated in FIG. 1, using an apparatus in which the multi-layered structure 204 is placed between the substrate 100 and the anode 220 (in the electrochemical processing apparatus), the consumption of a leveler, a accelerator, and a suppressor during plating were checked, respectively. A cation amine polymer with a molecular weight of 2500 was used as the leveler, bis(3-sulfopropyl) disulfide with a molecular weight of 310 was used as the accelerator, and polyethylene glycol with a molecular weight of 2200 was used as the suppressor. As the cation exchange film, polyacrylic resin having a sulfonic group was used, and as the filtration film, polypropylene was used. An experiment was conducted every day for 30 days. For comparison, the consumption of the leveler, the accelerator, and the suppressor were respectively checked in the case of only the filtration film, only the cation exchange film, and the absence of the filtration film and the cation exchange film.
FIGS. 3 to 5 illustrate the results. The conditions are as follows.
(1) Multi-layered structure (filtration film+cation exchange film: multi-layered structure 204)

(2) Only filtration film

(3) Only cation exchange film

(4) Absence of filtration film and cation exchange film

FIG. 3 illustrates the consumption of the leveler. Herein, the vertical axis represents the consumption of the leveler normalized with the case (1) using the multi-layered structure being 1. In any of the cases (1) to (3), the consumption of the leveler was reduced compared with the case (4) without using a film. However, in the case (3) using only the cation exchange film, the consumption of the leveler was increased about twice that of the case (1) using the multi-layered film. In the case (2) using only the filtration film, the consumption of the leveler was increased slightly compared with the case (1) using the multi-layered film; however, no large change was found. In any case, there was no change in film characteristics even after the elapse of 30 days.
FIG. 4 illustrates the consumption of the accelerator. Herein, the vertical axis represents the consumption of the accelerator normalized with the case (1) using the multi-layered film being 1. In any of the cases (1) to (3), the consumption of the accelerator was reduced compared with the case (4) without using a film. However, in the case (2) using only the filtration film, the consumption of the accelerator was increased by about 1.5 times that of the case (1) using the multi-layered film. In the case (3) using only the cation exchange film, the consumption of the accelerator was increased slightly compared with the case (1) using the multi-layered film; however, no large change was found. In any case, there was no change in film characteristics even after the elapse of 30 days.
FIG. 5 illustrates the consumption of the suppressor. Herein the vertical axis represents the consumption of the suppressor normalized with the case (1) using the multi-layered film being 1. In any of the cases (1) to (3), the consumption of the suppressor was reduced compared with the case (4) without using a film. In the case (2) using only the filtration film and the case (3) using only the cation exchange film, the consumption of the accelerator was increased slightly compared with the case (1) using the multi-layered film; however, no large change was found. In any of the cases, there was no change in film characteristics even after the elapse of 30 days.
As described above, by using the multi-layered structure 204, the consumption of all the three additives: the leveler, the accelerator, and the suppressor were reduced simultaneously.
The embodiment of the present invention has been described with reference to the drawings. However, it is represented merely for an illustrative purpose, and other various configurations can also be adopted.
In the embodiment, the case where the anode 220 is a copper anode has been illustrated. However, as the anode 220, an insoluble anode may be used. Even in this case, the multi-layered structure 204 can be configured in the same way as in the above; however, it may be configured so as not to transmit copper ions, for example.
Furthermore, in the above-mentioned embodiment, copper plating has been illustrated, in which the plating solution contains copper ions. However, the present invention can be applied to other various plating. For example, the present invention can be applied to the plating in which bumps of a semiconductor device are formed using nickel or the like. Even in this case, as an anode, any of a dissoluble or insoluble anode may be used.

Claims

1. An electrochemical processing apparatus, comprising:

a chamber; and

a multi-layered structure provided to partition the chamber into an anode region and a cathode region, said structure including a filtration film facing said cathode region and a cation exchange film facing said anode region.

2. The apparatus according to claim 1, wherein the filtration film and the cation exchange film are provided in contact with each other.

3. The apparatus according to claim 1, wherein the filtration film has a hole diameter of 0.5 μm or less.

4. The apparatus according to claim 1, wherein:

the chamber has a plating solution containing a leveler, an accelerator, and a suppressor introduced into the cathode region; and

the multi-layered structure is configured to suppress transmission of the accelerator, the leveler, and the suppressor.

5. The apparatus according to claim 1, wherein the anode is made of copper.

6. The apparatus according to claim 5, wherein the multi-layered structure is configured to allow transmission of copper ions.

7. A chamber including an anode and a cathode, a filtration film provided in the chamber between the anode and the cathode, and

a cation exchange film provided in the chamber between the

8. The chamber according to claim 7, the cathode is a filtration film and the anode.

semiconductor wafer.

9. A method of plating a conductive film by use of an electrochemical processing apparatus which includes a chamber with an anode, a cathode, a filtration film between the anode and the cathode and a cation exchange film between the filtration film and the anode, the method comprising plating a semiconductor substrate into the chamber as the cathode,

applying an electric power between the anode and the semiconductor substrate to plate a conductive film on the semiconductor substrate.

10. The method according to claim 9, further comprising introducing a plating solution containing a leveler, an accelerator, and a suppressor into the chamber.

11. The method according to claim 10, wherein the anode comprising a copper so that a copper film is plated on the semiconductor substrate.