JPH02200800A - Method for adjusting current distribution for electroplating - Google Patents

Abstract

PURPOSE:To easily adjust a current distribution by each of sub-segmented plating areas by combining small anodes which can be individually set at desired current values to form a assembled anode, disposing such anode to face a surface to be plated and properly adjusting the currents of the individual small anodes. CONSTITUTION:For example, 16 pieces of the small anodes 1 which can be set individually at the desired current values are combined to a net shape to form the assembled anode 5 and this anode is so installed as to face the surface 10 to be plated of a substrate 11 to be plated. A plating liquid 13 of a plating cell 14 is fed by a pump 15 to the assembled anode 5 and is brought into contact with the surface 10 to be plated through the assembled anode 5; thereafter, the liquid is returned to the plating cell 14. The currents flowing out of the small anodes 1 are insulated by an anode frame 2 and are, therefore, kept at the set values when the currents are supplied to the small anodes 1, which are respectively properly set, of the assembled anode 5 from a power source 6 in this constitution. The current distribution well reflecting the individual current set values is obtd. when the currents emit from the assembled anode 5. Desired plating patterns are formed on the surface 10 to be plated in this way.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to adjustment of plating current distribution for uniformity of plating thickness distribution in electroplating, and particularly in fine pattern selective electroplating method. This invention relates to a plating current distribution adjustment method using a small anode assembling machine whose current value can be set.

[Conventional technology]

Conventionally, the uniformity of plating film thickness distribution in electroplating is
Generally, this was done by installing an auxiliary cathode or shielding plate around the plating area where the current concentrates (that is, the plating film becomes thicker) to alleviate the current concentration. When manufacturing high-density wiring boards, such as those for mounting LSIs, using the selective electroplating method, the entire plating area is viewed macroscopically with the main purpose of improving the difference in plating film thickness between the periphery and the center of the plating area. A current distribution adjustment method that takes into account the

[Problem to be solved by the invention]

The conventional current distribution adjustment method described above attempts to adjust the current distribution by considering the entire plating area macroscopically, so it is difficult to selectively electroplat When manufacturing by the method, the density of the wiring pattern within the plating area (i.e., when the plating area is divided into small areas, the density is as high as the maximum allowed by the design rules unique to each product). Local distribution of plating current caused by areas with wiring and areas with almost no wiring f4. (i.e., non-uniformity of plating film thickness) cannot be solved. In addition, improving the auxiliary cathode and shielding plate so that the S flow distribution can be adjusted for each subdivided plating area has the disadvantage that they must be replaced for each object to be plated, and the current distribution can also be adjusted. In order to exhibit their full effect, they must be brought very close to the object to be plated, which has the disadvantage of causing poor plating deposition due to poor circulation of the plating solution.

An object of the present invention is to provide a method for adjusting current distribution in electroplating that solves the above problems.

[Means to solve the problem]

In order to achieve the above object, the method for adjusting electroplating current distribution of the present invention includes disposing a composite anode, which is a combination of at least two small anodes each of which can individually set a desired current value, facing the surface to be plated. , and by appropriately adjusting the current of each small anode, the plating current distribution in the area to be plated is adjusted.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a front view of a composite anode used in an electroplating current distribution adjustment method according to an embodiment of the present invention.
Although the small anodes 1 are combined to form a rectangular composite anode, it is a matter of course that the scope of the present invention is not limited thereto. In the figure, 3 is an anode frame and 4 is an anode lead wire.

FIG. 2 is a longitudinal sectional view of FIG. 1. The small anode 1 is a net-like anode plate made of, for example, platinum-plated titanium mesh. The anode frame 2 is made of heat-resistant vinyl chloride, for example.
It is a lid with 16 partitions and a frame without a bottom. The small anodes 1 are fixedly attached to the anode frame 2, and further electrically insulated from each other. The anode frame 3 is a support for attaching the anode frame 2 to a plating tank or the like, and is made of, for example, heat-resistant vinyl chloride. The anode lead wire 4 is, for example, a platinum-plated titanium wire coated with a resin, and is connected to each of the small anodes 1, penetrates the anode frame 3, and is drawn out.

FIG. 3 is a longitudinal cross-sectional view for explaining the action of a composite anode of an embodiment of an electroplating apparatus employing the current distribution adjustment method of the present invention. Composite 111fi5 is the anode according to the invention described in FIGS. 1 and 2 above. The plating power source 6 is a plating current supply source having the number of channels corresponding to the number of small anodes 1. The + power supply line 7 is a lead wire that connects each positive side channel of the plating power supply 6 to the anode lead wire 4 drawn out from the small anode 1, respectively. In addition, in Figure 3, it becomes complicated, so 1
The ten feeder lines 7 of the book are shown, and the others are omitted. - The power supply bus 8 is a lead wire that collectively connects the negative side of the plating power source 6 to the substrate to be plated. The cathode terminal is plated on the substrate 11
A terminal for making good electrical contact with the terminal. The surface to be plated 10 is a part to be plated using the current distribution adjustment method of the present invention. The substrate 11 to be plated is a component having a surface 10 to be plated. Further details will be explained with reference to FIGS. 4 and 5. The holder 12 is a jig for holding the substrate 11 to be plated in an appropriate position relative to the composite anode 5. The plating solution 13 is an electrolytic solution for depositing a predetermined plating film on the surface 10 to be plated. Plating [14 is an electroplating apparatus main body consisting of a service tank, a plating solution Wi ring pipe, and a plating chamber. Pump 15 is a pump for circulating plating liquid.

Next, its effect will be explained. First, the circulation path of the plating solution will be explained. The plating solution 13 flows through the circulation pipe in the direction of the arrow by the pump 15 and reaches the composite anode 5 . Since the small anode 1 incorporated in the composite anode &i5 is reticulated,
The plating solution 13 passes through the composite anode 5 while contacting the small anode 1, rises further, and contacts the surface to be plated 10. The plating solution 13 that has reached the substrate 10 to be plated overflows from the gap between the substrate 11 to be plated and the holder 12 and returns to the service tank below.4 Next, the flow of plating current will be explained. The current sent from the plating power source 6 to each small anode 1 through the power supply 117 is sent to the plated object 10 through the plating solution 13. Furthermore, a method for adjusting the zero-order current distribution that is collected at the cathode terminal 9 and returned to the plating power source 6 through the -power supply bus 8 will be described. Almost all of the current supplied to the appropriately set small anodes 1 flows toward the plating target 10, and the current flowing toward the pump 15 can be ignored. The current flowing out from the small anode 1 is kept at a set value because it is insulated from each other by the anode frame 2 while it travels inside the composite anode ai5. The current emitted from the composite anode 5 no longer has the partitioning effect of the anode frame 2, so they mix with each other, resulting in a current distribution determined by the spatial shape formed by the plated object 10, the composite anode 5, and the holder 12. However, it is possible to obtain a current distribution that reflects the current setting value of each small anode 1, which is different from the current distribution emitted from a single anode. Therefore, for the current distribution adjustment method of the present invention, the distance between the composite 111 [i5 and the plated surface 10 has an important meaning, and in this example, an effective current adjustment effect can be obtained at a distance of 100 m or less. Ta.

FIG. 4 is an explanatory front view of the substrate 11 to be plated.

The plating pattern 16 is a part on which plating is deposited to form a wiring, and is located on the substrate 11 to be plated.

FIG. 5 is an explanatory cross-sectional view of the substrate 11 to be plated.

The electrode thin film 17 is a metal thin film that becomes a plated electrode formed by, for example, sputtering or the like. The insulating substrate 18 is a base board of a high-density wiring board.Through holes 19 are conductors that pass through the insulating substrate 18 for external output and the like. The plating resist 20 is a coating film for performing selective plating, and a wiring pattern is drawn by photolithography or the like.

〔Effect of the invention〕

As explained above, the present invention has a composite anode in which at least two small anodes, each of which can be individually set to a desired current value, are combined and arranged to face a surface to be plated, and the current of each small anode is controlled. By appropriately adjusting the current distribution, it is possible to adjust the current distribution for each subdivided area by changing the current value setting, which is easy to do, without causing plating deposition defects due to insufficient circulation of the plating solution. There is.

[Brief explanation of the drawing]

FIG. 1 is a front view of the composite anode of the present invention, FIG. 2 is a sectional view taken along the line A-A in FIG. FIG. 5 is an explanatory diagram of a cross section of the substrate to be plated. 1...Small anode 3...Anode frame 5...Composite anode 7...Ten power supply lines 9...#%@2f- 11...Substrate to be plated 13...Plating solution 15. ... Bonfu. 17... Electrode thin film 19... Through hole

Claims (1)

[Claims] (1) By arranging a composite anode in which at least two or more small anodes, each of which can be individually set to a desired current value, face the surface to be plated, and appropriately adjusting the current of each small anode. , a method for adjusting current distribution in electroplating, which comprises adjusting the plating current distribution in an area to be plated.