JP3886919B2 - Plating equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plating apparatus for electrolytically plating a metal on a material to be plated, and more particularly to a plating apparatus suitable for forming a metal film on a semiconductor wafer.
[0002]
[Prior art]
Methods for forming a metal thin film include a sputtering method, a CVD (Chemical Vapor Deposition) method, and an electrolytic plating method. Among these, the electrolytic plating method has the advantages that the manufacturing equipment is cheaper and the film forming speed is faster than the sputtering method and the CVD method. For this reason, the electrolytic plating method is used in many fields such as a manufacturing process of a magnetic head, a damascene process of a semiconductor device, and a wiring formation process of a printed wiring board.
[0003]
FIG. 1 is a schematic view showing an example of a conventional electrolytic plating apparatus for plating a metal on a semiconductor wafer. The plating tank 71 for containing the plating solution 72 is formed of an insulating material such as vinyl chloride. A fixing jig 73 for fixing a wafer 81 as a material to be plated is disposed on one side wall of the plating tank 71. The fixing jig 73 is also formed of an insulating material such as vinyl chloride, and is provided with an opening 79 having a size slightly smaller than that of the wafer 81. The wafer 81 is fixed to the fixing jig 73 from the outside while being attached to the wafer attachment portion 78. When the wafer 81 is fixed to the fixing jig 73 in this way, a feeding point (terminal) 75 provided on the fixing jig 73 comes into contact with the surface edge of the wafer 81. The feeding point 75 is electrically connected to the negative terminal of the power supply device 80.
[0004]
An anode electrode 74 is disposed in the plating tank 71. The anode electrode 74 is electrically connected to the positive terminal of the power supply device 80. A drain valve 76 is provided at the bottom of the plating tank 71, and the plating solution 72 in the plating tank 71 is discharged via the drain valve 76.
[0005]
2A to 2C are cross-sectional views showing a conventional plating method in the order of steps.
[0006]
First, as shown in FIG. 2A, a conductive seed layer 82 is formed on the wafer 81 by sputtering metal.
[0007]
Next, as shown in FIG. 2B, a photoresist is applied on the seed layer 82 to form a photoresist film 83. The photoresist film 83 is exposed and developed to expose the seed layer 82. The opening 84 to be formed is formed in a predetermined pattern.
[0008]
Next, as shown in FIG. 1, the wafer 81 is attached to the wafer attachment portion 78, and the wafer attachment portion 78 is fixed to the fixing jig 73. As a result, the feeding point 75 provided on the fixing jig 73 comes into contact with the seed layer 82 on the surface of the wafer 81. Thereafter, the plating solution 72 is put into the plating tank 71, and power is supplied from the power supply device 80 to the anode electrode 74 and the feeding point 75. Then, the seed layer 82 in contact with the feeding point 75 becomes a cathode, and metal ions in the plating solution 72 are deposited on the seed layer 82 and are not covered with the resist film 83 as shown in FIG. A metal film (plating film) 85 is formed on part of the seed layer 82. In order to form a good plating film, it is important to control the temperature and composition of the plating solution and the amount of current.
[0009]
Next, after the plating solution 72 is discharged from the plating tank 71, the wafer 81 is removed from the fixing jig 73 and the resist film 83 is removed. In this way, a metal film 85 having a predetermined pattern is formed on the wafer 81.
[0010]
By the way, in the plating apparatus, when the plating solution 72 is put into the plating tank 71 or when the plating solution 72 is discharged from the plating tank 71, power is supplied to the anode electrode 74 and the feeding point 75. This is for the following reason. That is, when the seed layer 82 is made of a material that is electrically lower than the feeding point 75, as shown in FIG. 3A, when the feeding point 75 touches the plating solution 72, the seed layer 82 and the feeding point 75 A local battery (part indicated by a broken line in the figure) is formed, and the seed layer 82 is dissolved in the plating solution 72. Further, when the seed layer 82 is made of a material that is electrically lower than the metal film (plating film) 85, the adhesion between the resist film 83 and the metal film 85 is insufficient as shown in FIG. The seed layer 82 and the metal film 85 form a local battery (portion indicated by a broken line in the figure), and the seed layer 82 is dissolved in the plating solution 72. When the seed layer 82 is dissolved in this manner, not only the accuracy of the plating process is lowered, but also problems such as the occurrence of corrosion and a decrease in reliability occur.
[0011]
In order to avoid the occurrence of such a problem, when the plating solution 72 is put into the plating tank 71 or when the plating solution 72 is discharged from the plating tank 71, the anode electrode 74 and the feeding point 75 are fed to the seed. The dissolution of the layer 82 is prevented.
[0012]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-80996 (FIG. 8)
[0013]
[Problems to be solved by the invention]
However, the above-described plating method using the conventional plating apparatus has the following problems. That is, as shown in FIG. 4, when the level of the plating solution 72 is lower than the position of the lower end of the opening 79 of the fixing jig 73 while the plating solution 72 is being discharged, the fixing jig 73. And the wafer 81, the plating solution 72 remains at the corner (the portion indicated by the arrow A in the figure), and a so-called liquid pool is generated. As described above, since the power is supplied to the anode electrode 74 and the feeding point 75 while the plating solution 72 is being discharged, the plating proceeds in the portion of the liquid pool, although it is slight. At this time, since the temperature, composition, and current amount of the plating solution 72 are not controlled, the surface of the plating film is rough and not glossy, and a so-called roughness is generated.
[0014]
Japanese Patent Application Laid-Open No. 2002-80996 describes a plating apparatus provided with a cleaning treatment tank that injects a cleaning liquid or the like onto a processing object while rotating the processing object after plating. However, even with this apparatus, it is impossible to prevent the roughening that occurs when the plating solution is discharged as described above.
[0015]
In view of the above, an object of the present invention is to provide a plating apparatus capable of preventing the plating from progressing when the plating solution is discharged and the surface of the plating film from becoming rough.
[0020]
[Means for Solving the Problems]
The problem described above is that in the plating apparatus in which the plating material is fixed to a fixing member having an opening and the plating solution and the material to be plated are brought into contact with each other through the opening of the fixing member. This is solved by a plating apparatus in which a permeable member capable of penetrating the plating solution is disposed on the wall surface of the plate.
[0021]
In the present invention, a permeable member made of glass fiber or carbon fiber is disposed on the wall surface of the opening. For this reason, when the plating solution is discharged from the plating tank, the plating solution on the surface of the material to be plated permeates into the permeable member due to capillary action, and further moves to the lower side of the opening due to gravity. Thereby, it is avoided that the plating liquid pool is generated in the opening. In this case as well, it is preferable to provide a discharge groove at the lower end of the opening and discharge the plating solution collected at the lower part of the opening to the outside of the opening through the discharge groove.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0027]
(First embodiment)
FIG. 5 is a schematic diagram showing the plating apparatus according to the first embodiment of the present invention.
[0028]
The plating tank 11 for containing the plating solution 12 is formed of an insulator such as vinyl chloride. On one side wall of the plating tank 11, a fixing jig 13 for fixing the wafer 21 which is a material to be plated is disposed. The fixing jig 13 is also formed of an insulator such as vinyl chloride.
[0029]
The fixing jig 13 is provided with a circular opening 19. The cross-sectional shape of the opening 19 is tapered, and the opening diameter inside the plating tank 11 is larger than the opening diameter outside (the material to be plated) of the plating tank 11. The taper angle θ of the opening 19 is preferably 30 ° or more. In the present embodiment, the taper angle of the opening 19 is 45 °.
[0030]
The wafer 21 is fixed to the fixing jig 13 from the outside while being attached to the wafer attachment portion 18. When the wafer 21 is attached to the fixing jig 13 in this way, the feeding point 15 provided on the fixing jig 13 comes into contact with the surface edge of the wafer 21. The feeding point 15 is made of a metal such as platinum and is electrically connected to the negative terminal of the power supply device 20.
[0031]
An anode electrode 14 is disposed in the plating tank 11. The anode electrode 14 is electrically connected to the positive terminal of the power supply device 20. Further, a drain valve 16 is provided at the bottom of the plating tank 11, and the plating solution 12 in the plating tank 11 is discharged through the drain valve 16.
[0032]
6A to 6C and FIG. 7 are cross-sectional views illustrating a plating method using the above-described plating apparatus.
[0033]
First, as shown in FIG. 6A, a conductive seed layer 22 is formed by sputtering metal on the entire upper surface of the wafer 21.
[0034]
Next, as shown in FIG. 6B, a photoresist is applied on the seed layer 22 to form a photoresist film 23. The photoresist film 23 is exposed and developed to expose the seed layer 22. The opening 24 to be formed is formed in a predetermined pattern.
[0035]
Next, as shown in FIG. 5, the wafer 21 is attached to the wafer attachment portion 18, and the wafer attachment portion 18 is fixed to the fixing jig 13. As a result, the feeding point 15 provided on the fixing jig 13 contacts the seed layer 22 on the surface of the wafer 21. Thereafter, the plating solution 12 is put into the plating tank 11, and power is supplied from the power supply device 20 to the anode electrode 14 and the feeding point 15. Then, the seed layer 22 in contact with the feeding point 15 becomes a cathode, and metal ions in the plating solution 12 are deposited on the seed layer 22 and are not covered with the resist film 23 as shown in FIG. A metal film (plating film) 25 is formed on part of the seed layer 22.
[0036]
Next, as shown in FIG. 7, the drain valve 16 is opened to discharge the plating solution 12 from the plating tank 11. At this time, a predetermined voltage is applied to the anode electrode 14 and the feeding point 15. In the present embodiment, since the opening 19 of the fixing jig 13 is formed in a taper shape, the liquid in the opening 19 flows down along the tapered surface as the plating solution 12 is discharged, and the inside of the opening 19 It is possible to prevent a liquid pool from being generated.
[0037]
Thereafter, the wafer 21 is removed from the fixing jig 13 and the resist film 23 is removed. In this way, a metal film 25 having a predetermined pattern is formed on the wafer 21.
[0038]
As described above, in this embodiment, since the cross-sectional shape of the opening 19 of the fixing jig 13 is tapered, the plating solution in the opening 19 flows down along the tapered surface when the plating solution 12 is discharged. The occurrence of liquid pool is avoided. Therefore, the surface roughness of the plating film is avoided and a good plating film can be obtained.
[0039]
Hereinafter, the result of actually forming the plating film on the wafer by the above-described method and examining the surface state will be described.
[0040]
First, a silicon wafer was prepared, and an FeNi film having a thickness of 100 nm was formed as a seed layer on the silicon wafer by sputtering. And after apply | coating a photoresist on this FeNi film | membrane and forming a photoresist film, exposure and the image development process were performed, and the opening part was formed in the photoresist film with the predetermined pattern.
[0041]
Next, the silicon wafer was fixed to the fixing jig 13 of the plating apparatus shown in FIG. The taper angle θ of the opening 19 of the fixing jig 13 is 45 °.
[0042]
Using this plating apparatus, an FeNi film was plated on a silicon wafer until the thickness became about 2 μm. Thereafter, the drain valve 16 was opened and the plating solution 12 was discharged. At this time, no liquid pool occurred in the opening 19 of the fixing jig 13. Thereafter, the silicon wafer was removed from the fixing jig 13 and the resist film was removed. Then, the state of plating on the surface of the silicon wafer was examined. As a result, it was confirmed that a good plating film was obtained, and no roughness was observed on the surface of the plating film.
[0043]
(Second Embodiment)
FIG. 8 is a schematic view showing a plating apparatus according to a second embodiment of the present invention, and FIG. 9 is a perspective view showing an opening provided in a fixing jig of the plating apparatus. This embodiment is different from the first embodiment in that the cross-sectional shape of the opening of the fixing jig is different, and other structures are basically the same as those in the first embodiment. In FIG. 8, the same components as those in FIG.
[0044]
In the present embodiment, a substantially cylindrical opening 29 is provided in a fixing jig 23 for fixing a wafer 21 that is a material to be plated, and a plurality of rings extending in the circumferential direction are formed on the wall surface of the opening 29. A groove 29a is provided. In addition, a V-shaped discharge groove 29 b for discharging the plating solution from the groove 29 a is provided at the lower end of the opening 29.
[0045]
In the present embodiment, when the plating solution 12 is discharged from the plating tank 11, the plating solution 12 remaining in the opening 29 moves downward along the groove 29a and further flows downward from the discharge groove 29b. Accordingly, as in the first embodiment, no plating liquid pool is generated at the corners formed by the fixing jig 23 and the wafer 21, and the surface of the plating film is prevented from being rough and good. A plated film can be obtained.
[0046]
In the present embodiment, the case where a plurality of ring-shaped grooves 29a are formed on the wall surface of the opening 29 has been described. However, the shape of the groove is not limited to this, and for example, the wall surface of the opening 29 A net-like groove may be formed on the surface.
[0047]
(Third embodiment)
FIG. 10 is a schematic view showing a plating apparatus according to a third embodiment of the present invention. The difference between the present embodiment and the first embodiment is that the cross-sectional shape of the fixing jig is different, and the other structure is basically the same as that of the first embodiment. The same components as those in FIG.
[0048]
In the present embodiment, a substantially cylindrical opening 32 is formed in the fixing jig 31, and a permeable member 32 a made of glass fiber is provided on the wall surface of the opening 32. In addition, a discharge groove 32b for discharging the plating solution that has permeated the permeable member 32a is provided below the opening 32.
[0049]
In the present embodiment, when the plating solution 12 is discharged from the plating tank 11, the plating solution 12 on the surface of the wafer 21 is absorbed by the permeable member 32a by capillary action and moves to the lower part of the permeable member 32a by gravity. . Then, the plating solution 12 accumulated in the lower part of the permeable member 32a flows down from the discharge groove 32b. Accordingly, as in the first embodiment, no plating liquid pool is generated at the corners formed by the fixing jig 23 and the wafer 21, and the surface of the plating film is prevented from being rough and good. A plated film can be obtained.
[0050]
In the present embodiment, the case where glass fibers are used as the permeable member 32a has been described. However, as the permeable member 32a, a member made of a fiber other than glass fibers such as carbon fiber or a porous member is used. Also good.
[0051]
(Fourth embodiment)
FIG. 11 is a schematic view showing a plating apparatus according to a fourth embodiment of the present invention. This embodiment differs from the first embodiment in that the cross-sectional shape of the fixing jig is different, and the other structure is basically the same as that of the first embodiment. The same components as those in FIG.
[0052]
In the present embodiment, the fixing jig 41 is provided with a substantially cylindrical opening 42, and a plurality of injection ports 43 for injecting clean air are provided on the wall surface of the opening 42. The clean air is supplied from an external clean air supply source to the injection port 43 through a pipe.
[0053]
In the present embodiment, when the plating solution 12 is discharged from the plating tank 11, clean air is injected from the injection port 43 when the level of the plating solution 12 is below the lower end of the opening 42. As a result, the plating solution remaining in the opening 42 is scattered, so that no plating solution pool is generated in the corner formed by the fixing jig 41 and the wafer 21. Therefore, the surface roughness of the plating film is avoided and a good plating film can be obtained.
[0054]
In the present embodiment, clean air is ejected from the ejection port 43, but nitrogen gas (N ₂ ) or other gas may be ejected.
[0055]
(Fifth embodiment)
FIG. 12 is a schematic diagram showing a plating apparatus according to a fifth embodiment of the present invention. The difference between the present embodiment and the first embodiment is that the cross-sectional shape of the fixing jig is different, and the other structure is basically the same as that of the first embodiment. The same components as those in FIG.
[0056]
In the present embodiment, the fixing jig 51 is provided with a substantially cylindrical opening 52, and a plurality of injection ports 53 for injecting pure water are provided on the wall surface of the opening 52. Pure water is supplied from an external pure water supply source to the injection port 53 through a pipe.
[0057]
In the present embodiment, when the plating solution 12 is discharged from the plating tank 11, pure water is injected from the injection port 53 when the level of the plating solution 12 is lower than the lower end of the opening 52. Thereby, since the plating solution remaining in the opening 52 can be removed, the plating solution does not accumulate in the corner formed by the fixing jig 51 and the wafer 21. Therefore, the surface roughness of the plating film is avoided and a good plating film can be obtained.
[0058]
In the present embodiment, pure water is ejected from the ejection port 53, but other cleaning liquid may be ejected.
[0059]
(Sixth embodiment)
FIG. 13 is a schematic diagram showing a plating apparatus according to a sixth embodiment of the present invention. The difference between this embodiment and the first embodiment is that the cross-sectional shape of the fixing jig is different, and the other structure is basically the same as that of the first embodiment. The same components as those in FIG.
[0060]
In the present embodiment, the fixing jig 61 is made of a highly water-repellent fluororesin, and a substantially cylindrical opening 62 is provided at the center. In FIG. 13, the cross section of the opening 62 is cylindrical. However, as described in the first embodiment, the cross section of the opening 62 may be tapered.
[0061]
In the present embodiment, since the fixing jig 61 is formed of a highly water-repellent fluororesin, the plating solution in the opening 62 flows down along the wall surface of the opening 62 when the plating solution 12 is discharged, Generation of liquid pool is avoided. Therefore, the surface roughness of the plating film is avoided and a good plating film can be obtained.
[0062]
Note that although the case where a fluororesin is used as a highly water-repellent resin has been described in this embodiment, other resins having a water repellency equivalent to or higher than that of the fluororesin may be used. Further, the entire fixing jig 61 is not formed of a fluororesin, but only the periphery of the opening 62 is formed of a highly water repellent fluororesin, and the other part is formed of a resin having a relatively low water repellent property such as vinyl chloride It may be formed.
[0063]
(Additional remark 1) In the plating apparatus which fixes a to-be-plated material to the fixing member which has an opening part, and contacts a plating solution and a to-be-plated material via the opening part of the said fixing member, The plating apparatus is characterized in that the opening is formed in a taper shape having an opening area on the opposite side to an opening area on the plated material side.
[0064]
(Additional remark 2) The plating apparatus of Additional remark 1 characterized by the taper angle of the said opening part being 30 degrees or more.
[0065]
(Additional remark 3) In the plating apparatus which fixes a to-be-plated material to the fixing member which has an opening part, and contacts a plating solution and a to-be-plated material through the opening part of the said fixing member, A plating apparatus, wherein a groove extending along an edge of the opening is formed on the wall surface.
[0066]
(Supplementary Note 4) The plating apparatus according to Supplementary Note 3, wherein a discharge groove for discharging the plating solution in the groove on the wall surface is provided at a lower end portion of the opening.
[0067]
(Additional remark 5) In the plating apparatus which fixes a to-be-plated material to the fixing member which has an opening part, and contacts a plating solution and a to-be-plated material through the opening part of the said fixing member, A plating apparatus, wherein a permeable member capable of penetrating a plating solution is disposed on a wall surface.
[0068]
(Additional remark 6) The said permeable member is formed of at least one of glass fiber and carbon fiber, The plating apparatus of Additional remark 5 characterized by the above-mentioned.
[0069]
(Appendix 7) In a plating apparatus for performing electrolytic plating by fixing a material to be plated to a fixing member having an opening, and bringing a plating solution and a material to be plated into contact with each other through the opening of the fixing member, A plating apparatus characterized in that an injection port for injecting at least one of gas and liquid is provided on a wall surface.
[0070]
(Supplementary note 8) The plating apparatus according to supplementary note 7, wherein the gas ejected from the ejection port is one of clean air and nitrogen gas.
[0071]
(Supplementary note 9) The plating apparatus according to supplementary note 7, wherein the liquid ejected from the ejection port is pure water.
[0072]
(Additional remark 10) In the plating apparatus which fixes a to-be-plated material to the fixing member which has an opening part, and contacts a plating solution and a to-be-plated material through the opening part of the said fixing member, the said fixing member A plating apparatus characterized by being formed of a fluororesin or a resin having a water repellency equivalent to or higher than that.
[0073]
【The invention's effect】
As described above, according to the present invention, since the sectional shape of the opening provided in the fixing jig for fixing the material to be plated is tapered, the inside of the opening is discharged when the plating solution is discharged from the plating tank. In this way, no plating liquid pool is generated, and a good plating film free from roughness is obtained.
[0074]
According to another invention of the present application, since the groove extending along the edge of the opening is formed in the wall surface of the opening, the plating solution is lowered along the groove when the plating solution is discharged from the plating tank. It flows and the occurrence of a liquid pool in the opening is suppressed. Thereby, a favorable plating film is obtained.
[0075]
According to still another invention of the present application, since the permeable member is arranged on the wall surface of the opening, the plating solution adhering to the surface of the material to be plated is discharged to the permeable member when the plating solution is discharged from the plating tank. Absorption of the liquid is suppressed. Thereby, a favorable plating film is obtained.
[0076]
According to still another invention of the present application, since the injection port for injecting gas or liquid is provided on the wall surface of the opening, when the plating solution is discharged from the plating tank, the plating solution in the opening is scattered. The occurrence of liquid pool can be prevented. Alternatively, the plating solution in the opening can be washed away to prevent generation of a liquid pool. Thereby, a favorable plating film is obtained.
[0077]
According to still another invention of the present application, since the fixing jig for fixing the material to be plated is formed of a fluororesin or a resin having a water repellency equal to or higher than that, an opening is provided when discharging the plating solution from the plating tank. The plating solution in the part flows along the wall surface, and the liquid pool is not easily generated in the opening. Thereby, a favorable plating film is obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of a conventional electrolytic plating apparatus for plating a metal on a semiconductor wafer.
FIGS. 2A to 2C are sectional views showing a conventional plating method in the order of steps.
FIGS. 3A and 3B are schematic diagrams showing the reason why power is supplied to the anode electrode and the feeding point when the plating solution is put into the plating tank and when the plating solution is discharged from the plating tank. FIG.
FIG. 4 is a schematic view showing a problem of a conventional plating apparatus.
FIG. 5 is a schematic diagram showing the structure of the plating apparatus according to the first embodiment of the present invention.
FIGS. 6A to 6C are sectional views (No. 1) showing a plating method using the plating apparatus of the first embodiment. FIGS.
FIG. 7 is a sectional view (No. 2) showing a plating method using the plating apparatus of the first embodiment;
FIG. 8 is a schematic view showing a plating apparatus according to a second embodiment of the present invention.
FIG. 9 is a perspective view showing an opening provided in a fixing jig of the plating apparatus of the second embodiment.
FIG. 10 is a schematic diagram showing a plating apparatus according to a third embodiment of the present invention.
FIG. 11 is a schematic view showing a plating apparatus according to a fourth embodiment of the present invention.
FIG. 12 is a schematic diagram showing a plating apparatus according to a fifth embodiment of the present invention.
FIG. 13 is a schematic diagram showing a plating apparatus according to a sixth embodiment of the present invention.
[Explanation of symbols]
11, 71 ... plating tank,
12, 72 ... plating solution,
13, 23, 31, 41, 51, 61, 73 ... fixing jig,
14, 74 ... anode electrode,
15, 75 ... feeding point,
16, 76 ... drain valve,
18, 78 ... Wafer mounting portion,
19, 29, 32, 42, 52, 62, 79 ... opening,
20, 80 ... power supply,
21, 81 ... wafer,
22, 82 ... Seed layer,
23, 83 ... resist film,
25, 85 ... Metal film (plating film),
29a: groove on the wall surface of the opening,
32a ... permeable member,
32b ... discharge groove,
43, 53 ... injection port.

Claims (1)

In a plating apparatus that performs electrolytic plating by fixing a material to be plated to a fixing member having an opening, and contacting a plating solution and the material to be plated through the opening of the fixing member.
A plating apparatus, wherein a permeable member capable of penetrating a plating solution is disposed on a wall surface of the opening.

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