JP2005133113A - Plating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plating apparatus which provides a plated film with uniform thickness without needing preliminary determination for plating conditions. <P>SOLUTION: A plating apparatus 10 has a plating tank 12, an anode 14 and a cathode 16 arranged in the plating tank. The cathode 16 has at least divided two parts 16A and 16B, and each current flowing in the divided cathode parts is measured with ammeters 22 and 24, is fed back, and controlled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plating apparatus.

  In recent years, film formation by plating has been performed in a semiconductor damascene process, a magnetic head manufacturing process, a printed wiring board wiring formation process, and the like. Compared with other sputtering methods and CVD methods, the plating method is cheaper in manufacturing facilities and has a great cost advantage.

  In film formation by electroplating, an electric current is passed between the anode and the cathode to form a plating film. FIG. 6 is a view showing a conventional plating apparatus. K is a cathode and A is an anode. Arrows indicate electric lines of force. Conventionally, it is known that the electric force lines concentrate on the outer peripheral portion of the cathode, so that the plating film is thicker on the outer peripheral portion of the cathode than on the central portion.

  In order to solve this problem, an annular shielding plate is arranged around the lines of electric force, or an auxiliary cathode is arranged around the cathode so as to make the plating film thickness uniform.

  However, making the plating film thickness uniform with the shielding plate is not suitable for performing various types of plating because the shielding plate must be recreated one by one in accordance with the plating conditions and the pattern of the cathode. Further, in order to make the plating film thickness uniform with the auxiliary cathode, it is necessary to periodically remove the plating film attached to the auxiliary cathode. When the auxiliary cathode is removed and the deposited plating is removed by etching, the time for replacing the auxiliary cathode and the time for etching are required, which increases the number of steps. There is also a method of causing the reverse current to flow through the auxiliary cathode to dissolve the deposits in the plating solution. However, if dissolved quickly, the additive in the plating solution may be decomposed and the plating film may be deteriorated. When it is dissolved, it takes man-hours.

  Therefore, in order to solve such a problem, there is a proposal for making the plating film thickness uniform by dividing the anode into a plurality of parts and adjusting the current flowing through each of the anode parts (Patent Document 1, Patent Document 1). 2 and 3). For example, according to Patent Document 3, the anode is divided into a circular central portion and a donut-shaped outer peripheral portion surrounding the anode. As the current at the outer peripheral portion of the donut shape is reduced, the electric lines of force gathered at the outer peripheral portion of the cathode are reduced, and the plating film thickness can be made uniform. Alternatively, according to Patent Documents 1 and 2, by dividing the anode into a large number of parts in a matrix and independently controlling the current flowing through each part, the plating film can be made uniform even for complex cathodes. It becomes possible.

  However, in any of the conventional techniques, before performing the plating operation, the dummy plating operation is performed, and the thickness of the dummy plating film is measured, and then the plating conditions of the actual plating operation performed thereafter are adjusted. It was necessary.

JP 7-173700 A JP-A-7-102400 JP 2001-316687 A

  An object of the present invention is to provide a plating apparatus that does not require such conditions before plating and can obtain a uniform plating film thickness.

  The plating apparatus according to the present invention includes a plating tank, and an anode and a cathode disposed in the plating tank. The cathode is divided into at least two parts, and currents flowing through the divided cathode parts are respectively adjusted. It is characterized by including the means to do.

  According to this configuration, the cathode is divided into two or more parts, and the current flowing through each of the parts is measured. If the cathode area is known, the current value can be converted into a plating rate (film thickness per unit time). (If the plating efficiency is constant, the plating film thickness is equal to the plating rate × time.) That is, the final plating film thickness can be determined during plating by looking at the value of the current flowing through each of the divided cathode portions. If this is utilized, for example, the current value flowing in the divided cathode part is fed back, and the current setting of the divided anode part and the current value of the auxiliary cathode are adjusted, so that the current is divided during plating. The plating rate of the formed cathode portion can be adjusted to make the final film thickness uniform. In this way, the final film thickness can be made uniform by adjusting the plating rate of each part of the cathode during plating without setting the conditions before plating.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a plating apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the cathode and anode of FIG. 1 and 2, the plating apparatus 10 includes a plating tank 12 containing a plating solution. An anode 14 and a cathode 16 are disposed in the plating apparatus 10.

  Each of the anode 14 and the cathode 16 is divided into a plurality of parts, that is, at least two parts. In the illustrated embodiment, the anode 14 has a circular central portion 14A and a donut-shaped outer peripheral portion 14B around the central portion 14A. Corresponding to the anode 14, the cathode 16 has a circular central portion 16 </ b> A and a donut-shaped outer peripheral portion 16 </ b> B around the central portion 16 </ b> A.

  A first power supply 18 is disposed on a first wiring connecting the central portion 14A of the anode 14 and the cathode 16 (the central portion 16A and the outer peripheral portion 16B). The second power source 20 is disposed on the second wiring connecting the outer peripheral portion 14B of the anode 14 and the cathode 16 (the central portion 16A and the outer peripheral portion 16B). Further, the first ammeter 22 is arranged between the negative side of the first power supply 18 and the central portion 16A of the cathode 16 so as to measure only the current flowing through the cathode 16A, and the second ammeter 24 However, it is disposed between the negative side of the second power source 20 and the outer peripheral portion 16B of the cathode 16 so as to measure only the current flowing through the cathode 16B.

  The control device 26 receives the outputs of the first ammeter 22 and the second ammeter 24, and according to the current of the first power source 18 and the current of the central portion 16A of the cathode 16 and the current value of the outer peripheral portion 16B of the cathode 16. The second power supply 20 is feedback controlled. The first power source 18 and the second power source 20 have a current at the central portion 14A of the anode 14 (which increases the plating rate on the central portion 16A side of the cathode 16) and a plating rate at the outer peripheral portion 16B side of the cathode 16 (see FIG. It is provided separately for the current of the outer peripheral portion 14B of the anode 14. Then, based on the value of the current flowing in the central portion 16A of the cathode 16 and the value of the current flowing in the outer peripheral portion 16B of the cathode 16, the current flowing in the central portion 16A and the outer peripheral portion 16B of the cathode 16 is adjusted. )) Since the current in the central portion 14A of the anode 14 and the outer peripheral portion 14B of the anode 14 are controlled, the first power source 18 and the second power source 20 are controlled by the control device 26. The plating rate in the divided portions 16A and 16B can be adjusted without setting the conditions before plating.

  The anode 14 is configured as a metal member. The cathode 16 is configured as a metal film provided on a silicon chip, for example. In this case, it is not necessary to physically divide the silicon chip, and the metal film provided on the silicon chip may be electrically divided.

  The cathode 16 is configured as follows, for example. A Cu film is formed on the entire surface by sputtering as a seed for plating on a 6-inch silicon wafer. This Cu film becomes the cathode 16. The Cu film is patterned as shown in FIG. 2 to divide the cathode 16 into a circular central portion 16A having a diameter of 3 inches and a donut-shaped outer peripheral portion 16B having an outer diameter of 6 inches and an inner diameter of 3 inches. And the 1st and 2nd ammeters 22 and 24 are attached so that the electric current which flows through each of the center part 16A and the outer peripheral part 16B can be monitored.

  Furthermore, patterning for plating is performed on the Cu film on the silicon wafer using a resist. Next, the anode 14 is divided into a circular central portion 14A having a diameter of 3 inches and a donut-shaped outer peripheral portion 14B having an outer diameter of 6 inches and an inner diameter of 3 inches, and the first and second power sources 18, 20 are attached independently.

  In operation, the first and second ammeters 22 and 24 respectively measure the current flowing through the central portion 16A and the outer peripheral portion 16B of the cathode 16, and the measured values are input to the control device 26. Based on the measured values, the control device 26 determines the current values of the first and second power supplies 18 and 20 so that the current density (current value / plating area) flowing through the central portion 16A and the outer peripheral portion 16B of the cathode 16 is constant. Perform feedback control.

  For example, when a current of 70% (an arbitrary current value is assumed to be 100%) is passed through the central portion 14A of the anode 14 and a current of 30% is passed through the outer peripheral portion 14B, the central portion 16A and the outer peripheral portion of the cathode 16 The current density of 16B became equal. After the plating, the resist was peeled off and the plating film thickness was measured. According to the present invention, the plating film thickness variation was within ± 10% between the central portion 16A and the outer peripheral portion 16B.

  On the other hand, as a reference example, in a conventional method, a Cu film is formed as a seed for plating on a 6-inch silicon wafer on the entire surface by sputtering, and further, patterning for plating is performed using a resist, and the state is left as it is. As a result of plating, the outer peripheral portion of the silicon wafer was about 30% thicker than the central portion. Thus, in the conventional method, there was a variation in the plating film thickness of about ± 30%, but according to the present invention, the variation in the plating film thickness was within ± 10%.

  FIG. 3 is a view showing a modification of the cathode and the anode. The anode 14 is divided into an upper part 14A and a lower part 14B by a straight line. The cathode 16 is divided into an upper part 16A and a lower part 16B by a straight line corresponding to the anode 14. The cathode 16 is divided with a circle diameter or a string as a boundary.

  In this case, a Cu film is formed on the entire surface by sputtering as a seed for plating on a 6-inch silicon wafer. The Cu film is patterned as shown in FIG. 3 to divide the cathode 16 into two parts, an upper part 16A and a lower part 16B. And the 1st and 2nd ammeters 22 and 24 are attached so that the electric current which flows through each can be monitored. Furthermore, patterning for plating is performed using a resist. Next, the 6-inch anode 14 is divided into an upper part 14A and a lower part 14B.

  When the current value flowing through the upper part 14A and the lower part 14B of the anode 14 was adjusted so that the current density (current value / plating area) flowing through the upper part 16A and the lower part 16B of the cathode 16 would be constant, 60 %, The current density of the upper portion 16A and the lower portion 16B of the cathode 16 became equal when a current of 40% was passed through the lower portion 14B. After the completion of plating, the resist was peeled off and the plating film thickness was measured. As a result, the conventional method had a variation of about ± 20%, but according to the present invention, the variation was reduced to within ± 10%.

  In this case, as a conventional reference example, a Cu film was formed on the entire surface by sputtering as a seed for plating on a 6-inch silicon wafer, and patterning for plating was performed using a resist. Here, a pattern in which the upper half pattern area of the silicon wafer is wide (opening ratio 15%) and the lower half pattern area is narrow (opening ratio 10%) was used. When plating was performed as it was, the plating film thickness of the lower half of the wafer was about 20% thicker than the plating film thickness of the upper half of the wafer.

  FIG. 4 is a view showing a modification of the anode. Instead of the above-described anode 14, the anode 14 is divided into a plurality of portions 14C arranged in a matrix. A plurality of power supplies connected to the plurality of portions 14C are included. According to this configuration, the current in the plurality of portions of the cathode 16 can be controlled more finely, and the film thickness can be further uniformed.

  FIG. 5 is a view showing a plating apparatus according to a modification. Similar to the plating apparatus 10 of FIGS. 1 and 2, the plating apparatus 10 of FIG. 5 includes a plating tank 12, an anode 14, and a cathode 16, and the anode 14 and the cathode 16 are each divided into a plurality of portions. . The anode 14 has a circular central portion 14A and a donut-shaped outer peripheral portion 14B around the central portion 14A. The cathode 16 has a circular central portion 16A and a donut-shaped outer peripheral portion 16B around the central portion 16A. Furthermore, the 1st and 2nd power supplies 18 and 20, the 1st and 2nd ammeters 22 and 24, and the control apparatus 26 are provided (refer FIG. 1).

  In FIG. 5, a donut-shaped auxiliary cathode 28 is provided around the cathode 16. The auxiliary cathode 28 is connected to an independent power source and ammeter. The current value flowing through the auxiliary cathode 28 is adjusted so that the current density (current value / plating area) flowing through the central portion 16A and the outer peripheral portion 16B of the cathode 16 is constant. For example, when 150 percent of the current of the cathode 16 is passed through the auxiliary cathode 28, the current density of the central portion 16A and the outer peripheral portion 16B of the cathode 16 becomes equal. After the completion of plating, the resist was peeled off and the plating film thickness was measured. As a result, the conventional method had a variation of about ± 30%, but according to the present invention, the variation was within ± 10%.

  The present invention is not limited to the above embodiments described with reference to the drawings, and modifications can be made within the scope of the present invention. For example, the cathode can be divided into a plurality of parts in a shape different from that described above, and a mechanism for adjusting the current flowing through each of the parts can be provided.

  As described above, according to the present invention, the plating rate of each part of the cathode can be adjusted during plating without finalizing the conditions before plating, and the final film thickness can be made uniform. Can be made uniform, and contributes greatly to product reliability.

FIG. 1 is a view showing a plating apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing the cathode and anode of FIG. FIG. 3 is a view showing a modification of the cathode and the anode. FIG. 4 is a view showing a modification of the anode. FIG. 5 is a view showing a plating apparatus according to a modification. FIG. 6 is a view showing a conventional plating apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Plating apparatus 12 ... Plating tank 14 ... Anode 16 ... Cathode 18 ... Power source 20 ... Power source 22 ... Ammeter 24 ... Ammeter 26 ... Control device 28 ... Auxiliary cathode

Claims (4)

  A plating tank; and an anode and a cathode disposed in the plating tank, wherein the cathode is divided into at least two parts, and includes means for adjusting currents flowing through the divided cathode parts, respectively. And plating equipment.   The plating apparatus according to claim 1, wherein the anode is divided into at least two parts, and a power source is provided for each of the divided two parts of the anode.   The plating apparatus according to claim 1, wherein the cathode has a circular portion and a donut-shaped portion surrounding the circular portion.   The plating apparatus according to claim 1, wherein the cathode is divided by a substantially straight line.

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