JP2002241996A - Electroplating apparatus, plating solution retaining member for electroplating apparatus and method for producing copper wiring semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroplating apparatus by which a plated layer having a uniform film thickness can be formed. SOLUTION: The electroplating apparatus 1 is provided with the cathode 2 in contact with the object 5 to be plated, the anode 14 having a structure through which a plating solution 15 can pass, and a plating solution retaining member 21. The plating solution retaining member 21 is made of porous silicon carbide. The plating solution 15 is fed to the object 5 to be plated via the anode 14 and the plating solution retaining member 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electrolytic plating apparatus,
The present invention relates to a plating solution holding member for an electroplating apparatus and a method for manufacturing a copper wiring semiconductor.

[0002]

2. Description of the Related Art Techniques for forming wiring on a semiconductor wafer,
In particular, in recent years, attention has been focused on electrolytic copper plating using an electrolytic plating apparatus as a technique for forming copper wiring on a semiconductor wafer.

In a conventional general electrolytic plating apparatus, a semiconductor wafer is immersed in a plating solution in a state where a plating bath is filled with the plating solution, and a cathode is connected to the semiconductor wafer side to flow electricity. The membrane is to be made.

However, in order to form fine and uniform copper wiring using such a conventional apparatus, for example, it is necessary to flow a plating solution or to secure a certain distance between the cathode and the anode. Was. For this reason, the apparatus has tended to be large. In the case of this conventional device,
A large amount of plating solution is required for each film formation, which is disadvantageous in reducing the cost of the semiconductor.

Therefore, recently, a next-generation electrolytic plating apparatus capable of solving the above-mentioned problems has been proposed. This new electrolytic plating apparatus includes a plating solution supply unit, a cathode, an anode, a plating solution holding member, and the like. An anode is provided at the lower end of the plating supply unit. The anode is provided with a slit for allowing the plating solution to pass therethrough. A plating solution holding member made of porous alumina is provided on the lower surface side of the anode. On the other hand, a semiconductor wafer is supported in contact with the cathode. The upper surface of the semiconductor wafer and the lower surface of the plating solution holding member face each other with a slight gap therebetween.

Therefore, the plating solution supplied to the plating solution supply section passes through the slit of the anode, reaches the plating solution holding member, and is then supplied to the semiconductor wafer through the pores of the plating solution holding member. You. In this state, by energizing between the electrodes, electrolytic plating is performed on the semiconductor wafer, and fine copper wiring is formed even in a static bath.

[0007]

However, in the case of the conventional apparatus, since the plating solution holding member is made of porous alumina, the member is easily eroded by the plating solution. therefore,
Impurities such as heavy metals are eluted into the plating solution, which causes the composition of the plating solution to deteriorate. Therefore, there is a disadvantage that the deposition behavior of copper plating tends to be unstable, and a copper wiring having a uniform film thickness cannot be obtained.

The present invention has been made in view of the above problems, and an object thereof is to provide an electroplating apparatus and a plating solution holding member for an electroplating apparatus which can form a plating layer having a uniform thickness. It is in.

Another object of the present invention is to provide a method capable of reliably manufacturing a copper wiring semiconductor having a copper wiring having a uniform film thickness.

[0010]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, an anode having a structure through which a plating solution can pass, a cathode contacting an object to be plated,
An electrolytic plating apparatus comprising: a porous plating solution holding member disposed on the side of the plating object in the anode; wherein the plating solution is supplied to the plating object via the anode and the plating solution holding member. The gist of the present invention is an electrolytic plating apparatus characterized in that the plating solution holding member is made of porous silicon carbide.

According to a second aspect of the present invention, in the first aspect, the porosity of the plating solution holding member is 20% to 50%;
The average pore diameter was 10 μm to 60 μm. According to a third aspect of the present invention, in the first or second aspect, the value of the standard deviation in the pore size distribution when the pore size of the plating solution holding member is represented by a common logarithm is 0.20 or less.

The invention described in claim 4 is the first to third aspects of the present invention.
In any one of the above items, the plating solution holding member has a volume resistivity of 10 ¹ Ωm to 10 ⁵ Ωm. In a fifth aspect of the invention, a gist of the present invention is a plating solution holding member for an electrolytic plating apparatus made of porous silicon carbide.

According to the present invention, the copper wiring is formed on the semiconductor wafer by performing electrolytic copper plating on the semiconductor wafer using the plating solution holding member made of porous silicon carbide substantially as an anode. A gist is a method for manufacturing a copper wiring semiconductor, which is characterized by being formed.

The "action" of the present invention will be described below. According to the first and fifth aspects of the present invention, since the plating solution holding member is made of porous silicon carbide having a higher corrosion resistance than porous alumina, the member is less likely to be eroded by the plating solution, and Elution of impurities into the inside is prevented. This avoids the deterioration of the composition of the plating solution and stabilizes the deposition behavior of the plating. In addition, since the plating solution holding member is made of porous silicon carbide having better electrical conductivity than porous alumina, the member substantially functions as an anode. Therefore, the member, which is a pseudo anode, comes closer to the object to be plated, and a strong and stable electric field can be applied to the plating solution near the object to be plated.

According to the second aspect of the invention, by setting the values of the porosity and the average pore diameter of the plating solution holding member within the above-mentioned preferred ranges, the plating solution can uniformly exude from the member. . As a result, a plating layer having a uniform thickness can be reliably formed.

If the porosity is less than 20%, the plating solution becomes difficult to flow smoothly due to an increase in pressure loss, and the leaching of the plating solution varies depending on the location. There is a risk of non-uniformity. Conversely, when the porosity exceeds 50%, the increase in pressure loss can be avoided, but the property of holding the plating solution is impaired. Therefore, also in this case, the thickness of the plating layer may be uneven.

When the average pore diameter is less than 10 μm, the plating solution becomes difficult to flow smoothly due to an increase in pressure loss, so that the leaching of the plating solution varies depending on the location. There is a risk of non-uniformity. Conversely, when the average pore diameter exceeds 60 μm,
Although an increase in pressure loss can be avoided, the property of holding the plating solution is impaired. Therefore, also in this case, the thickness of the plating layer may be uneven.

According to the third aspect of the present invention, as a result that the pore diameters are uniform, the leaching of the plating solution does not vary depending on the location. Therefore, the thickness of the plating layer becomes more uniform.

According to the fourth aspect of the present invention, it is possible to reliably form a plating layer having a uniform thickness without increasing the cost. If an attempt is made to realize a material having a volume resistivity of less than 10 ¹ Ωm, it is difficult to select materials and set firing conditions, so that not only the production cost may increase, but also the porosity may be impaired. Conversely 1
0 ⁵ When it exceeds Ωm is becomes too low electrical conductivity, there is a possibility that the plating solution retaining member can not substantially function as an anode.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electrolytic copper plating apparatus 1 according to one embodiment of the present invention will be described below in detail with reference to FIG.

The cathode 2 constituting the electrolytic copper plating apparatus 1
Is an annular member whose diameter increases toward the upper end,
A flange 3 is formed on the lower end side. The cathode 2 is formed using, for example, a conductive metal material. The diameter of the lower end side opening 4 of the cathode 2 is set to be slightly smaller than the diameter of a semiconductor wafer (for example, a silicon wafer) 5 which is an object to be plated. The semiconductor wafer 5 is pressed against the flange 3 from below by a stage (not shown). As a result, the outer peripheral portion on the upper surface side of the semiconductor wafer 5 is in close contact with the lower surface side of the flange 3, and the semiconductor wafer 5 is held in this state. At this time, since the cathode 2 has a so-called bottomed shape, the electrolytic copper plating solution 15 is accumulated in a region formed on the upper surface side of the semiconductor wafer 5.

On the other hand, the anode holder 12 constituting the electrolytic copper plating apparatus 1 is arranged above and in close proximity to the cathode 2 in use. An opening 13 is provided at the lower end side of the anode holder 12, and a plate-shaped anode 14 is attached near the opening 13. Anode 14
Is formed in a circular shape using, for example, a conductive metal material. A plurality of slits 1 are formed in a plurality of portions of the anode 14 so as to allow the copper plating solution 15 to pass from the upper surface to the lower surface.
6 are provided. On the upper surface of the anode holder 12, a plating solution supply pipe 17 and a plating solution recovery pipe 18 are provided, respectively. The plating solution supply pipe 17 communicates a space 19 defined by the anode holder 12 and the anode 14 with a plating solution tank (not shown). Copper plating solution 1
When 5 is insufficient, the copper plating solution 15 is replenished into the space 19 via the plating solution supply pipe 17. When the amount of the copper plating solution 15 in the space 19 exceeds a certain amount, the plating solution recovery pipe 18 plays a role of collecting the surplus amount. Note that the recovered copper plating solution 15 is returned to the plating solution tank and reused.

The opening 13 of the anode holder 12 has the anode 1
4, a plating solution holding plate 21 is provided as a plating solution holding member. The plating solution holding plate 21 has substantially the same size and substantially the same shape as the anode 14. Plating solution holding plate 21
Also, the copper plating solution 15 is held in its own pores, thereby preventing the copper plating solution 15 from flowing out from the lower surface side when the anode holder 12 is transferred. Note that the lower surface of the plating solution holding plate 21 is opposed to the upper surface of the semiconductor wafer 5 with a slight gap therebetween. Specifically, in the present embodiment, the size of the gap is set to be about 1 mm. Further, on the outer peripheral portion of the plating solution holding plate 21, a shield rubber 2 for preventing seepage of the copper plating solution 15 from the portion is provided.
2 are provided.

Next, the material and the like of the plating solution holding plate 21 used in the present embodiment will be described in detail. The plating solution holding plate 21 of the present embodiment is made of a porous ceramic material, specifically, made of porous silicon carbide (porous SiC). The reason why porous silicon carbide was selected is that porous silicon carbide is excellent in corrosion resistance and electric conductivity as compared with porous alumina, and is extremely convenient as a material for the plating solution holding plate 21.

The porosity of the plating solution holding plate 21 is 20
% To 50%, and more preferably 30% to 45%. The average pore diameter is 10 μm to 60 μm
And more preferably 20 μm to 50 μm.

When the porosity is less than 20%, the copper plating solution 15 is difficult to flow smoothly due to an increase in pressure loss, so that the leaching of the copper plating solution 15 varies from place to place. That is, the amount of the copper plating solution 15 supplied from the lower surface side of the plating solution holding plate 21 becomes uneven, and as a result, the thickness of the copper plating layer may become uneven. Conversely, if the porosity exceeds 50%, an increase in pressure loss can be avoided, but the property of holding the copper plating solution 15 is impaired. Therefore, also in this case, the thickness of the plating layer may be uneven.

When the average pore diameter is less than 10 μm, the copper plating solution 15 is difficult to flow smoothly due to an increase in pressure loss, so that the leaching of the copper plating solution 15 varies from place to place. That is, the amount of the plating solution 15 supplied from the lower surface side of the plating solution holding plate 21 becomes uneven, and as a result, the thickness of the copper plating layer may become uneven. Conversely, when the average pore diameter exceeds 60 μm, an increase in pressure loss can be avoided, but the copper plating solution 1
5 is impaired. Therefore, also in this case, the thickness of the copper plating layer may be non-uniform.

The standard deviation in the pore size distribution when the pore size in the plane of the plating solution holding plate 21 is represented by a common logarithm is preferably 0.20 or less, particularly preferably 0.18 or less. That is, it is desirable that the pore diameters in the plane (especially in the lower side surface facing the semiconductor wafer 5 side) be as uniform as possible.

When the value of the standard deviation exceeds the above value, that is, when the pore diameters are not uniform, the leaching of the copper plating solution 15 varies depending on the location.
That is, the amount of the copper plating solution 15 supplied from the lower surface side of the plating solution holding plate 21 becomes uneven, and as a result, the thickness of the copper plating layer may become uneven.

The plating solution holding plate 21 preferably has a volume resistivity of 10 ¹ Ωm to 10 ⁵ Ωm, preferably 10 ² Ωm.
More preferably, it is 10 ⁴ Ωm. Volume resistivity is 1
If it is desired to realize a material having a resistivity of less than 0 ¹ Ωm, it is difficult to select a material and set firing conditions, and the production cost of the plating solution holding plate 21 may be increased. Also,
In addition, the porosity of the plating solution holding plate 21 may be impaired, and the basic performance of the plating solution holding property may be impaired. On the other hand, if it exceeds 10 ⁵ Ωm, the electrical conductivity becomes too low, and the plating solution holding plate 2
1 may not function substantially as the anode 14. Therefore, the copper plating solution 1 near the upper surface of the semiconductor wafer 5
5 may not be able to provide a strong and stable electric field.

The plating solution holding plate 21 has a density of 1.6 g / cm ^{3 to} 2.5 g / cm ³ and a bending strength of 30 g / cm ^3.
MPa to 150 MPa, Young's modulus is 50 GPa to 200
GPa, thermal conductivity 50W / m · K to 150W / m · K
It is good to be. As the porous silicon carbide forming the plating solution holding plate 21, high-purity porous silicon carbide is preferably used. Specifically, it is preferable to use porous silicon carbide in which the concentration of heavy metal as an impurity is 0.5% or less.

Here, a method for manufacturing the plating solution holding plate 21 of the present embodiment will be described. First, one or more silicon carbide powders as raw materials are prepared. Then, after blending a solvent, a binder, and the like with the silicon carbide powder, they are mixed well. Then, after drying the mixture, the dried mixture is granulated. Then, molding is performed using the granules obtained in the granulation step as a material to produce a disk-shaped molded body. In this case, it is preferable to set the conditions so that the density distribution during molding falls within the range of ± 0.05 g / cm ³ . In the present embodiment, a hydrostatic press is employed as a press method for achieving this. Next, the formed body obtained by the forming step is sintered under normal pressure at a temperature of about 2000 ° C. to 2300 ° C. in an inert atmosphere to sinter the formed body to obtain a sintered body (ie, a plating solution holding plate). 21) is obtained. In this case, the conditions are preferably set so that the in-plane temperature distribution of the molded body during firing falls within ± 1 ° C.

Next, a method of using the electrolytic copper plating apparatus 1 using the plating solution holding plate 21 configured as described above will be described. In the case of the electrolytic copper plating apparatus 1, the copper plating solution 15 supplied through the plating solution supply pipe 17 is used.
Are stored in the space 19 in a certain amount. The copper plating solution 15 supplied to the space 19 is supplied to the anode 1
4 through the slit 16 of the plating solution holding plate 21
To reach. Then, the copper plating solution 15 is further supplied to the upper surface side of the semiconductor wafer 5 through the pores of the plating solution holding plate 21. Therefore, by supplying electricity between the anode 14 and the cathode 2 in this state, electrolytic copper plating is performed in a still bath. Then, a copper plating layer is deposited on the upper surface side of the semiconductor wafer 5 so as to fill the wiring groove dug in advance, and as a result, a copper wiring having a desired pattern shape is formed.

[0034]

EXAMPLES [Example 1] In the production of Example 1, as raw material silicon carbide powder, GC @ 240 (manufactured by Shinano Electric Refinery Co., Ltd., average particle size of 57 μm) and GMF-15H2 (manufactured by Pacific Random Co., 0.5 μm) in a weight ratio of 7: 3. Then, water and an acrylic resin as a binder were further added to these two kinds of silicon carbide powders, and these were mixed well using a pot mill. After drying the uniform mixture obtained in the mixing step for a predetermined time to remove water to some extent, an appropriate amount of the dried mixture was collected and granulated by a spray dryer.

Then, using the granules obtained by the granulation step as materials, hydrostatic pressing was performed at a pressure of about 100 MPa to 130 MPa to produce a disk-shaped molded body. Next, the molded body obtained by the molding step was fired under normal pressure at a temperature of 2100 ° C. to 2200 ° C. in an argon atmosphere. As a result, a disk-shaped plating solution holding plate 21 made of porous silicon carbide was obtained.

In the plating solution holding plate 21 of Example 1, the porosity is about 25%, the average pore diameter is about 15 μm, the standard deviation is 0.18, the volume resistivity is 10 ³ Ωm,
The density was 2.4 g / cm ³ , the bending strength was 130 MPa, the thermal conductivity was 140 W / m · K, and the heavy metal concentration was 0.5% or less.

Then, when electrolytic copper plating was performed using such a plating solution holding plate 21, it was possible to form a copper wiring having a uniform thickness on the semiconductor wafer 5. [Example 2] In the production of Example 2, as raw material silicon carbide powder, GC @ 240 (manufactured by Shinano Electric Refining Co., Ltd., average particle size of 57 μm) and GMF-15H2 (manufactured by Pacific Random Co., Ltd.
(Average particle size: 0.5 μm) in a weight ratio of 9: 1. Then, water and an acrylic resin as a binder were further blended with these two kinds of silicon carbide powders, and granulation was performed simultaneously while thoroughly mixing them using a universal mixer.

Then, using the granules obtained by the mixing and granulating steps as materials, a hydrostatic pressure press was performed at a pressure of about 50 MPa to produce a disk-shaped compact. Next, the molded body obtained by the molding step was subjected to 225 under an argon atmosphere.
It was fired at a temperature of 0 ° C. under normal pressure. As a result, a disk-shaped plating solution holding plate 21 made of porous silicon carbide was obtained.

The plating solution holding plate 21 of Example 2 has a porosity of about 40%, an average pore diameter of about 30 μm, a standard deviation of 0.18, a volume resistivity of 10 ³ Ωm,
The density was 1.9 g / cm ³ , the bending strength was 50 MPa, the thermal conductivity was 80 W / m · K, and the heavy metal concentration was 0.5% or less.

Then, when electrolytic copper plating was performed using such a plating solution holding plate 21, it was possible to form copper wiring having a uniform film thickness on the semiconductor wafer 5.

Therefore, according to the present embodiment, the following effects can be obtained. (1) The plating solution holding plate 21 of the electrolytic copper plating apparatus 1 is made of porous silicon carbide. That is, since the plating holding plate 21 is made of a material having better corrosion resistance than porous alumina, it is hardly corroded by the copper plating solution 15 and elution of heavy metals into the copper plating solution 15 is prevented. Thereby, the composition deterioration of the copper plating solution 15 is avoided,
The deposition behavior of plating is stabilized. In addition, since the plating solution holding plate 21 is made of a material having higher electrical conductivity than porous alumina, the plating solution holding plate 21 itself is substantially the same as the anode 14.
Will play a role. Therefore, the plating solution holding plate 21 as the pseudo anode 14 is brought closer to the semiconductor wafer 5. As a result, a strong and stable electric field can be applied to the copper plating solution 15 near the semiconductor wafer 5.

For the above reasons, according to the electrolytic copper plating apparatus 1 of the present embodiment, a copper plating layer (ie, copper wiring) having a uniform film thickness can be efficiently formed on the semiconductor wafer 5. (2) In the electrolytic copper plating apparatus 1, the values of the porosity and the average pore diameter of the plating solution holding plate 21 are set within the above preferred ranges. Therefore, the plating solution holding plate 21
The copper plating solution 15 can uniformly exude from the lower surface side of
As a result, a copper plating layer having a uniform thickness can be reliably formed.

(3) In the electrolytic copper plating apparatus 1, the value of the standard deviation in the pore diameter distribution when the pore diameter of the plating solution holding plate 21 is represented by a common logarithm is set within the above-mentioned preferred range. . Therefore, the pore diameters become uniform, and the leaching of the copper plating solution 15 does not vary from place to place. Therefore, the thickness of the copper plating layer becomes more uniform.

(4) In this electrolytic copper plating apparatus 1, the value of the volume specific resistance of the plating solution holding plate 21 is set within the above-mentioned preferred range. Therefore, it is possible to reliably form a copper plating layer having a uniform thickness without increasing the cost.

(5) Since the plating solution holding plate 21 of the present embodiment is made of hard silicon carbide, even if the plating solution holding plate 21 comes into contact with another member when the anode holder 12 is transferred, it is unlikely to crack or chip. Therefore, an apparatus having excellent durability can be obtained.

(6) In the present embodiment, the plating solution holding plate 21 made of porous silicon carbide having excellent electric conductivity is substantially used as the anode 14, and the semiconductor wafer 5
Electrolytic copper plating is applied on top. Therefore, according to such a manufacturing method, it is possible to reliably manufacture a copper wiring semiconductor having a copper wiring having a uniform thickness.

The embodiment of the present invention may be modified as follows. The electrolytic plating apparatus 1 according to the embodiment can be used not only for performing electrolytic copper plating, but also for performing, for example, electrolytic nickel plating or electrolytic gold plating.

The object to be plated is not limited to the semiconductor wafer 5 made of silicon, gallium arsenide, or the like, and may be, for example, a ceramic, metal, or plastic base material.

The electroplating apparatus 1 of the embodiment can be used not only for forming wirings but also for forming external connection terminals in a semiconductor such as a bump. Further, the electroplating apparatus 1 is used not only for forming a metal layer for the purpose of flowing electricity as in the above-described wiring, but also for forming a metal layer not particularly for the purpose of flowing electricity. It can be done.

The upper surface of the plating solution holding plate 21 may be arranged in a non-contact state with the lower surface of the anode 14. -Instead of the slit 16 in the anode 14, a hole penetrating in the thickness direction may be formed.

The anode 14 itself may be made of porous silicon carbide, and may be used as a plating solution holding member. According to this configuration, since the number of components is reduced, the configuration of the electrolytic plating apparatus 1 can be simplified.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) A plating solution is supplied to the plating object through the anode, which has a porous anode having a structure through which the plating solution can pass and a cathode in contact with the plating object, and serves also as a plating solution holding member. An electrolytic plating apparatus, wherein the anode is made of porous silicon carbide. Therefore, according to the invention described in the technical idea 1, the configuration of the device can be simplified.

[0053]

As described in detail above, according to the first to fourth aspects of the present invention, it is possible to provide an electrolytic plating apparatus capable of forming a plating layer having a uniform thickness.

According to the fifth aspect of the present invention, it is possible to provide a plating solution holding member for an electrolytic plating apparatus capable of forming a plating layer having a uniform thickness. According to the invention described in claim 6, it is possible to provide a manufacturing method capable of reliably manufacturing a copper wiring semiconductor having a copper wiring having a uniform film thickness.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an electrolytic copper plating apparatus according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electrolytic copper plating apparatus as an electrolytic plating apparatus, 2 ... Cathode, 5 ... Semiconductor wafer as an object to be plated, 14 ... Anode, 21 ... Plating solution holding plate as a plating solution holding member.

Claims (6)

[Claims] An anode having a structure through which a plating solution can pass, a cathode in contact with an object to be plated, and a porous plating solution holding member arranged on the anode side of the anode on the object to be plated; An electrolytic plating apparatus, wherein a plating solution is supplied to the object to be plated via the anode and the plating solution holding member, wherein the plating solution holding member is made of porous silicon carbide. 2. The plating solution holding member has a porosity of 20% to 20%.
2. The electrolytic plating apparatus according to claim 1, wherein the average pore diameter is 50 μm and the average pore diameter is 10 μm to 60 μm. 3. 3. The standard deviation value in the pore diameter distribution when the pore diameter of the plating solution holding member is represented by a common logarithm is 0.1.
The electrolytic plating apparatus according to claim 1, wherein the number is 20 or less. 4. The plating solution holding member has a volume resistivity of 1
0 ¹ Ωm~10 ⁵ electroplating device according to any one of claims 1 to 3, characterized in that it is [Omega] m. 5. A plating solution holding member for an electrolytic plating apparatus comprising porous silicon carbide. 6. A copper wiring is formed on a semiconductor wafer by subjecting a semiconductor wafer to electrolytic copper plating using a plating solution holding member made of porous silicon carbide substantially as an anode. A method for manufacturing a copper wiring semiconductor.