PLATING DEVICE

Abstract

A plating device for plating a substrate includes a plating solution container for retaining a plating solution. The plating solution container has a sidewall and an opening portion surrounded with the sidewall. Further, the plating device includes a holding member for holding the substrate so that the substrate faces the opening portion of the solution container and is situated away from the plating solution container; a cathode electrode for contacting with an outer circumferential portion of the substrate; an anode electrode for contacting the plating solution in the plating solution container; a plating solution supply device for supplying the plating solution into the plating solution container so that the plating solution overflows through a space between the plating solution container and the substrate after the plating solution contacts with the substrate; and a through hole formed in the sidewall of the plating solution container.

Description

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

[0001] The present invention relates to a plating device. In particular, the present invention relates to a plating device for plating a semiconductor wafer or a semiconductor substrate.

[0002] A conventional plating device is provided for uniformly plating a semiconductor wafer. Various types of conventional plating devices have been proposed (refer to Patent References 1 to 4). [0003] Patent Reference 1: Japanese Patent Publication No. 2003-306793 [0004] Patent Reference 2: Japanese Patent Publication No. 08-74088 [0005] Patent Reference 3: Japanese Patent Publication No. 2000-195823 [0006] Patent Reference 4: Japanese Patent Publication No. 2000-328291

[0007] FIG. 7 is a schematic sectional view showing a conventional plating device 2'. FIG. 8 is a schematic plan view showing the conventional plating device 2'. It is noted that a wafer pressing member 88' is omitted in FIG. 8.

[0008] As shown in FIG. 7, in the conventional plating device 2', a ring member 80' is disposed on a circumferential portion outside an upper portion of a cup portion 20'. Electrode pins 70' are disposed on the ring member 80' with an interval of 120 degrees. A wafer placing portion 72' is disposed at a distal end portion of each of the electrode pins 70'. Accordingly, a wafer 90' is placed on the wafer placing portions 72' at an outer circumferential portion thereof. More specifically, the wafer 90' is placed on the wafer placing portions 72' such that a surface 90' (a plating surface) of the wafer 90' faces toward the cup portion 20' (a lower side in FIG. 7).

[0009] Further, in the conventional plating device 2', the wafer pressing member 88' is placed on a backside surface 94' of the wafer 90', so that the wafer pressing member 88' presses the wafer 90' toward the lower side in FIG. 7. Accordingly, the wafer 90' is fixed with the wafer pressing member 88' and the wafer placing portions 72' of the electrode pins 70'. A space 82 is created between the surface 92' of the wafer 90' and an upper end portion 24' of the cup portion 20'.

[0010] Further, in the conventional plating device 2', an anode plate 50' is disposed on a bottom circumferential portion 26' of the cup portion 20'. An anode electrode 52' is provided for fixing the anode plate 50'.

[0011] In the conventional plating device 2', a plating solution 60' containing copper ions (Cu²+) is supplied into the cup portion 20' through a supply inlet 22' formed in a bottom portion 28' of the cup portion 20' at a center thereof. Then, the plating solution 60' flows toward a center portion of the wafer 90' placed at the upper portion of the cup portion 20'. Afterward, the plating solution 60' flows toward an outer circumferential portion of the wafer 90', and then is overflowed through the space between the wafer 90' and the upper end portion 24' of the cup portion 20'.

[0012] In the conventional plating device 2', a voltage applied between the anode plate 50' and the electrode pins 70', so that an electrical current flows between the anode plate 50' and the electrode pins 70'. Accordingly, an electrical current flows through the wafer 90', so that the surface 92' of the wafer 90' is plated.

[0013] In the conventional plating device 2' shown in FIG. 7, the electrical current flows to the outer circumferential portion of the wafer 90' through the electrode pins 70'. Accordingly, as opposed to the center portion of the wafer 90', an electrical current density tends to increase at the outer circumferential portion of the wafer 90'. As a result, the surface 92' of the wafer 90' tends to be plated at a greater rate at the outer circumferential portion of the wafer 90'.

[0014] FIG. 9 is a schematic plan view of the wafer 90' after the wafer 90' is plated with the conventional plating device 2'. As shown in FIG. 9, when the wafer 90' is plated with the conventional plating device 2', an outer circumferential portion 96' of the wafer 90' tends to have a larger plating thickness as opposed to that at a center portion 95' of the wafer 90'. Further, a peripheral region 97' near the electrode pin 70' tends to have a still larger plating thickness, thereby making it difficult to obtain a uniform plating thickness.

[0015] In view of the problems described above, an object of the present invention is to provide a plating device capable of solving the problems of the conventional plating device. In the present invention, it is possible to obtain a plating film with a uniform thickness.

[0016] Further objects and advantages of the invention will be apparent from the following description of the invention.

SUMMARY OF THE INVENTION

[0017] In order to attain the objects described above, according to a first aspect of the present invention, a plating device for plating a substrate includes a plating solution container for retaining a plating solution. The plating solution container has a sidewall and an opening portion surrounded with the sidewall.

[0018] Further, the plating device includes a holding member for holding the substrate so that the substrate faces the opening portion of the solution container and is situated away from the plating solution container; a cathode electrode for contacting with an outer circumferential portion of the substrate; an anode electrode for contacting the plating solution in the plating solution container; a plating solution supply device for supplying the plating solution into the plating solution container so that the plating solution overflows through a space between the plating solution container and the substrate after the plating solution contacts with the substrate; and a through hole formed in the sidewall of the plating solution container.

[0019] According to a second aspect of the present invention, the through hole may be arranged to face the cathode electrode.

[0020] According to a third aspect of the present invention, the through hole may be arranged at a position to face the cathode electrode and another position to not face the cathode electrode.

[0021] According to a fourth aspect of the present invention, the plating device may further include an opening size adjusting member for adjusting an opening size of the through hole.

[0022] In the present invention, the plating device is capable of forming a plating film with a uniform thickness.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic sectional view showing a plating device according to a first embodiment of the present invention;

[0024] FIG. 2 is a schematic plan view showing the plating device in a state that a wafer pressing member is omitted according to the first embodiment of the present invention;

[0025] FIGS. 3(A) and 3(B) are schematic sectional views showing a wafer to be plated with the plating device according to the first embodiment of the present invention, wherein FIG. 3(A) is a schematic sectional view showing the wafer before the plating device plates the wafer and FIG. 3(B) is a schematic sectional view showing the wafer after the plating device plates the wafer;

[0026] FIG. 4 is a schematic sectional view showing a plating device taken along a line 4-4 in FIG. 2 according to a second embodiment of the present invention;

[0027] FIG. 5 is a schematic sectional view showing a plating device taken along the line 4-4 in FIG. 2 according to a third embodiment of the present invention;

[0028] FIG. 6 is a schematic plan view showing a plating device in a state that a wafer pressing member is omitted according to a fourth embodiment of the present invention;

[0029] FIG. 7 is a schematic sectional view showing a conventional plating device;

[0030] FIG. 8 is a schematic plan view showing the conventional plating device in a state that a wafer pressing member is omitted; and

[0031] FIG. 9 is a schematic plan view showing a wafer plated with the conventional plating device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0032] Hereunder, preferred embodiments of the present invention will be explained with reference to the accompanying drawings.

First Embodiment

[0033] A first embodiment of the present invention will be explained. FIG. 1 is a schematic sectional view showing a plating device 1 according to the first embodiment of the present invention. FIG. 2 is a schematic plan view showing the plating device 1 in a state that a wafer pressing member 88 is omitted according to the first embodiment of the present invention.

[0034] As shown in FIGS. 1 and 2, the plating device 1 includes a base portion 10, a cup portion 20 disposed on the base portion 10, a ring portion 80 disposed above an upper portion of the cup portion 20 at an outer circumferential portion thereof; electrode pins 70 disposed on the ring portion 80; and the wafer pressing member 88.

[0035] In the embodiment, the base portion 10 has a supply opening portion 12 at a center portion thereof for supplying a plating solution 60. The cup portion 20 is disposed on the base portion 10. The cup portion 20 includes a sidewall portion 30 and a bottom portion 28.

[0036] In the embodiment, the plating device 1 has an opening portion 31 surrounded with the sidewall portion 30 at the upper portion of the cup portion 20, so that the sidewall portion 30 and the bottom portion 28 form a plating solution bath 21. A supplying opening portion 22 is formed in the bottom portion 28 at a center portion thereof for supplying the plating solution 60 into the plating solution bath 21. The supply opening portion 12 formed in the base portion 10 communicates with the supplying opening portion 22 formed in the cup portion 20.

[0037] In the embodiment, the ring portion 80 is disposed above the upper portion of the cup portion 20 at the outer circumferential portion thereof, and the electrode pins 70 are disposed on the ring portion 80 with an equal interval for functioning as a cathode electrode. The electrode pins 70 are disposed, for example, at three locations for plating a six-inch wafer or six locations for plating an eight-inch wafer. Accordingly, the electrode pins 70 are disposed with the 120 degree interval or the 60 degree interval, respectively. The following description, the electrode pins 70 are disposed at three locations as an example.

[0038] In the embodiment, a wafer placing portion 72 is formed at a distal end portion of each of the electrode pins 70, so that an outer circumferential portion of a wafer 90 is placed on the wafer placing portions 72. Further, the outer circumferential portion of the wafer 90 contacts with the wafer placing portions 72. The wafer 90 is placed such that a front surface 92 thereof (a plating surface) faces an opening portion 31 of the cup portion 20 downwardly in FIG. 1 (toward the cup portion 20). The wafer pressing member 88 presses the wafer 90 from a backside surface 94 thereof downwardly in FIG. 1, so that the wafer pressing member 88 and the wafer placing portions 72 of the electrode pins 70 fix the wafer 90. A space 82 is formed between the front surface 92 of the wafer 90 and an upper edge portion 24 of the cup portion 20.

[0039] In the embodiment, slits 32 are formed in the sidewall portion 30 of the cup portion 20 near the upper edge portion 24 thereof to penetrate the sidewall portion 30. More specifically, the slits 32 are formed at six locations with an equal interval of 60 degrees. Three of the slits 32 are disposed just below the electrode pins 70 to face the electrode pins 70.

[0040] In the embodiment, an anode plate 50 is disposed on a bottom circumferential portion 26 of the cup portion 20, and an anode electrode 52 fixes the anode plate 50. The anode plate 50 and the node electrode 52 are arranged to contact with the plating solution 60. Further, the anode electrode 52 and the electrode pins 70 are connected to a plating power source (not shown).

[0041] In the embodiment, a plating solution container 40 is arranged outside the cup portion 20. A pump 42 is connected to the supply opening portion 12 of the base portion 10 for supplying the plating solution 60 from the plating solution bath to the plating solution bath 21.

[0042] In the embodiment, the plating solution 60 contains, for example, copper ions (Cu²+). When the pump 42 supplies the plating solution 60 from the plating solution bath to the plating solution bath 21 in the cup portion 20 through the supply opening portion 12 of the base portion 10 and the supplying opening portion 22 of the cup portion 20, the plating solution 60 flows toward a center portion of the wafer 90 placed at the upper portion of the cup portion 20, so that the plating solution 60 contacts with the front surface 92 (the plating surface) of the wafer 90.

[0043] Afterward, the plating solution 60 flows toward the outer circumferential portion of the wafer 90, and overflows through the space 82 between the upper edge portion 24 of the cup portion 20 and the wafer 90. Accordingly, the plating solution 60 flows through a space 83 between the upper edge portion 24 of the cup portion 20 and the ring portion 80, so that the plating solution 60 returns from the plating solution bath 21 to the plating solution container 40 arranged outside the cup portion 20. Further, the plating solution 60 flows through the slits 32 formed in the sidewall portion 30 of the cup portion 20, so that the plating solution 60 returns from the plating solution bath 21 to the plating solution container 40 arranged outside the cup portion 20.

[0044] In the embodiment, when the wafer 90 is plated, a voltage is applied between the anode plate 50 and the electrode pins 70 to flow an electrical current there between. Accordingly, the electrical current flows through the wafer 90, so that the front surface 92 of the wafer 90 is plated.

[0045] A method of plating the front surface 92 of the wafer 90 will be explained in more detail next with reference to FIGS. 3(A) and 3(B). FIGS. 3(A) and 3(B) are schematic sectional views showing the wafer 90 to be plated with the plating device 1 according to the first embodiment of the present invention. More specifically, FIG. 3(A) is a schematic sectional view showing the wafer 90 before the plating device 1 plates the wafer 90, and FIG. 3(B) is a schematic sectional view showing the wafer 90 after the plating device 1 plates the wafer 90.

[0046] When the plating device 1 plates the wafer 90, first, a sheet payer 110 is disposed on the entire surface of the front surface 92 (the plating surface) of the wafer 90. Then, a resist layer 112 is selectively formed on the sheet layer 110, so that an opening portion 114 is formed. Instead of the resist layer 112, a resist film may be disposed on the sheet layer 110.

[0047] In the next step, while the sheet layer 110 is connected to the electrode pins 70, a voltage is applied between the anode plate 50 and the electrode pins 70 to flow an electrical current there between. As a result, an electrical current flows through the sheet layer 110 formed on the front surface 92 of the wafer 90. Accordingly, the following ion reaction occurs on the front surface 92 of the wafer 90, so that a copper plating layer 120 is formed in the opening portion 114 of the resist layer 112 as shown in FIG. 3(B).

Cu²++2e.sup.-→Cu

[0048] In general, the electrical current flows from the outer circumferential portion of the wafer 90 through the electrode pins 70. Accordingly, a current density tends to be higher at the outer circumferential portion of the wafer 90 as compared with the center portion of the wafer 90.

[0049] In the plating device 1 according to the embodiment, the slits 32 are formed in the sidewall portion 30 of the cup portion 20. Accordingly, the plating solution 60 flows out from the plating solution bath 21 through the slits 32 formed in the sidewall portion 30 of the cup portion 20 as well. As a result, a reduced amount of the plating solution 60 overflows through the space 82 between the upper edge portion 24 of the cup portion 20 and the wafer 90, so that a reduced amount of the plating solution 60 contacts with the outer circumferential portion of the wafer 90.

[0050] Accordingly, an amount of copper ions Cu²+ supplied to the outer circumferential portion of the wafer 90 for forming the plating layer 120 decreases. As a result, growth of the plating layer 120 at the outer circumferential portion of the wafer 90 is restricted. Accordingly, it is possible to prevent the plating layer 120 from excessively increasing at the outer circumferential portion of the wafer 90, thereby making it possible to obtain the plating layer 120 with a uniform thickness over the entire surface of the wafer 90.

[0051] As described above, in the embodiment, the slits 32 are formed in the sidewall portion 30 of the cup portion 20 near the upper edge portion 24 thereof to penetrate the sidewall portion 30. More specifically, the slits 32 are formed at six locations with an equal interval of 60 degrees. Three of the slits 32 are disposed just below the electrode pins 70 to face the electrode pins 70, remaining three of the slits 32 are disposed between the electrode pins 70 to not face the electrode pins 70.

[0052] As shown in FIG. 9, when the wafer 90' is plated with the conventional plating device 2', the outer circumferential portion 92' of the wafer 90' tends to have a larger plating thickness as opposed to that at the center portion 95' of the wafer 90'. Further, the peripheral region 97' near the electrode pin 70' tends to have a still larger plating thickness, thereby making it difficult to obtain a uniform plating thickness.

[0053] To this end, in the embodiment, it may be configured such that the slits 32 disposed just below the electrode pins 70 have an opening area greater than that of the slits 32 disposed between the electrode pins 70. In this case, as opposed to a case that all of the slits 32 have an identical opening area, it is possible to obtain a uniform plating thickness of the supply opening portion 120 over the entire surface of the wafer 90.

Second Embodiment

[0054] A second embodiment of the present invention will be explained next. FIG. 4 is a schematic sectional view showing the plating device 1 taken along a line 4-4 in FIG. 2 according to the second embodiment of the present invention.

[0055] As shown in FIG. 4, different from the first embodiment, the plating device 1 includes a shutter portion 34 disposed on a front side of the slit 32 to be slidable in a horizontal direction. Other configurations of the plating device 1 in the second embodiment are similar to those in the first embodiment. The shutter portion 34 may be disposed on the front side of each of the slits 32.

[0056] In the embodiment, when the shutter portion 34 slides in the horizontal direction, it is possible to adjust an opening size of the slit 32. Accordingly, it is possible to adjust an amount of the plating solution 60 flowing outside the cup portion 20 from the plating solution bath 21 through the slit 32. When the shutter portion 34 is disposed on the front side of the slit 32, it is possible to adjust the amount of the plating solution 60 flowing outside the cup portion 20 from the plating solution bath 21 through the slit 32.

Third Embodiment

[0057] A third embodiment of the present invention will be explained next. FIG. 5 is a schematic sectional view showing the plating device 1 taken along the line 4-4 in FIG. 2 according to the third embodiment of the present invention.

[0058] As described above, in the second embodiment shown in FIG. 4, the shutter portion 34 is disposed to be slidable in the horizontal direction. In the third embodiment, the shutter portion 34 is disposed to be slidable in a vertical direction. The shutter portion 34 may be disposed on the front side of each of the slits 32.

[0059] In the embodiment, when the shutter portion 34 slides in the vertical direction, it is possible to adjust the opening size of the slit 32. Accordingly, it is possible to adjust the amount of the plating solution 60 flowing outside the cup portion 20 from the plating solution bath 21 through the slit 32. When the shutter portion 34 is disposed on the front side of the slit 32, it is possible to adjust the amount of the plating solution 60 flowing outside the cup portion 20 from the plating solution bath 21 through the slit 32.

Fourth Embodiment

[0060] A fourth embodiment of the present invention will be explained next. FIG. 6 is a schematic plan view showing the plating device 1 in a state that the wafer pressing member 88 is omitted according to the fourth embodiment of the present invention.

[0061] As shown in FIG. 6, the slits 32 are disposed just below the electrode pins 70 with an equal interval of 120 degrees to face the electrode pins 70. In other words, different from the first embodiment, the slits 32 are not disposed between the electrode pins 70. Other configurations of the plating device 1 in the fourth embodiment are similar to those in the first embodiment.

[0062] In the embodiment, the plating solution 60 flows out from the plating solution bath 21 through the slits 32. Accordingly, a reduced amount of the plating solution 60 overflows through the space 82 between the upper edge portion 24 of the cup portion 20 and the wafer 90, so that a reduced amount of the plating solution 60 contacts with the outer circumferential portion of the wafer 90. Accordingly, it is possible to prevent the thickness of the plating layer 120 from increasing at the outer circumferential portion of the wafer 90, thereby making it possible to obtain the plating layer 120 with a uniform thickness over the entire surface of the wafer 90.

[0063] In the first and second embodiments, the slits 32 are disposed not only just below the electrode pins 70 but also between the electrode pins 70. Accordingly, it is possible to obtain the plating layer 120 with a uniform thickness especially in a case in which a difference in the thickness of the plating layer 120 becomes large between the center portion of the wafer 90 and the outer circumferential portion of the wafer 90. On the other hand, in the fourth embodiment, the slits 32 are not disposed between the electrode pins 70. Accordingly, it is possible to obtain the plating layer 120 with a uniform thickness especially in a case in which a difference in the thickness of the resist layer 112 is not excessively large between the center portion of the wafer 90 and the outer circumferential portion of the wafer 90. In addition to obtaining the plating layer 120 with a uniform thickness over the entire surface of the wafer 90, as compared with the first embodiment, it is possible to form the plating layer 120 at a faster rate.

Fifth Embodiment

[0064] A fifth embodiment of the present invention will be explained next. In the fifth embodiment, the slits 32 are disposed just below the electrode pins 70 with an equal interval of 120 degrees to face the electrode pins 70. In other words, different from the first embodiment, the slits 32 are not disposed between the electrode pins 70. Further, in the fifth embodiment, the shutter portion 34 is disposed to be slidable in the horizontal direction (refer to FIG. 4) or in the vertical direction (refer to FIG. 5). The shutter portion 34 may be disposed on the front side of each of the slits 32. Other configurations of the plating device 1 in the fifth embodiment are similar to those in the first embodiment.

[0065] As explained, in the fifth embodiment, the shutter portion 34 is disposed on the front side of the slit 32. Accordingly, it is possible to more precisely adjust the amount of the plating solution 60 flowing outside the cup portion 20 from the plating solution bath 21 through the slit 32.

[0066] The disclosure of Japanese Patent Application No. 2010-142853, filed on Jun. 23, 2010, is incorporated in the application by reference.

[0067] While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.

Claims

1. A plating device for plating a substrate, comprising: a plating solution container for retaining a plating solution, said plating solution container including a sidewall and an opening portion surrounded with the sidewall; a holding member for holding the substrate so that the substrate faces the opening portion of the solution container and is situated away from the plating solution container; a cathode electrode for contacting with an outer circumferential portion of the substrate; an anode electrode for contacting the plating solution in the plating solution container; a plating solution supply device for supplying the plating solution into the plating solution container so that the plating solution overflows through a space between the plating solution container and the substrate after the plating solution contacts with the substrate; and a through hole formed in the sidewall of the plating solution container.

2. The plating device according to claim 1, wherein said through hole is arranged at a location to face the cathode electrode.

3. The plating device according to claim 1, wherein said through hole is arranged at a location to face the cathode electrode and a location away from the cathode electrode.

4. The plating device according to claim 1, further comprising an opening size adjusting member for adjusting an opening size of the through hole.

Images