JP2789650B2 - Electroplating method and electroplating apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroplating method for forming a plating film on a plate-shaped member to be plated, and an electroplating apparatus used therefor.

[Conventional technology]

2. Description of the Related Art A hybrid infrared image sensor in which bump electrodes made of a soft metal such as indium are formed on a semiconductor chip for photoelectric conversion and a silicon IC semiconductor chip for signal processing, and the bump electrodes are thermocompression-bonded to each other has been known. The bump electrodes are typically made of a soft metal such as indium and have a diameter of 25 μm, a height of 10 μm, and a pitch of 50 μm, for example, 64 × 64. In addition, the formation method is such that a resist film having an opening is formed on a plating base metal film, and then a bump electrode is formed by plating only on the opening using the plating base metal film as a cathode. This is to remove the underlying metal film.

[Problems to be solved by the invention]

However, since a soft metal such as indium is easily oxidized, the surface of the In plating bump 6 formed on the plating base metal 2 of the substrate 1 is immediately covered with an oxide film in the conventional plating method as shown in FIG. Had been broken. When such an oxide film is formed on the surface of the bump electrode, a bonding failure occurs during thermocompression bonding, which tends to cause an increase in electric resistance and a decrease in mechanical strength. Especially HgCdTe as a semiconductor chip for photoelectric conversion
When a crystal is used, there are restrictions on the applied temperature and pressure, and sufficient bonding cannot be achieved. Such an inadequately joined portion results in a pixel defect, which has been regarded as a major problem in manufacturing.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of electroplating a bump electrode capable of preventing the formation of a surface oxide film after the formation of a plating film and performing sufficient thermocompression bonding, and an electroplating apparatus used therefor.

[Means for solving the problem]

In order to achieve the above object, in the electroplating method according to the present invention, the electroplating is performed by supplying a plating solution to a plating tank in which a member to be plated and an anode plate are arranged to face each other. Is discharged in an inert gas atmosphere,
Next, a cleaning liquid is supplied to wash the member to be plated, and then the member to be plated is taken out while maintaining the inert gas atmosphere. Further, in the electroplating apparatus for carrying out the above method, a plating tank having therein an anode plate disposed to face the member to be plated and capable of being sealed by filling a plating solution, and evacuating the plating tank to a vacuum, Or a mechanism for introducing an inert gas, and a mechanism for switching, supplying, circulating and discharging a plating solution and a cleaning solution to the plating tank.

[Action]

Oxidation of the plating film formed on the surface is mainly caused by contact of oxygen in the air after plating. In the electroplating method of the present invention, the plating solution is discharged in an inert gas atmosphere after the plating film is formed, so that there is no contact with oxygen.
Subsequently, the member to be plated is cleaned by supplying a cleaning liquid such as pure water. However, the member to be plated is also in an inert gas atmosphere, and there is no oxygen even though there is moisture, so there is almost no oxidation. After the cleaning, the member to be plated is taken out while keeping the atmosphere of the inert gas, and stored in a storage box, whereby a plated film without an oxide film can be obtained.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are enlarged sectional views showing a process of forming an In-plated bump to which the electroplating method of the present invention is applied, and FIG. 2 is a plan view of a plating apparatus used to carry out the process. It is a partial sectional view showing one example. As shown in FIG. 1 (a), a member to be plated on which a plating film is to be formed is a resist film 3 having a plating base metal 2 formed on a flat substrate 1 and an opening 4 provided thereon. Are formed as masks.

In FIG. 2, the plating apparatus includes a member 12 to be plated.
A plating tank 11 which has an anode plate 13 arranged opposite to and which can be filled and sealed with the plating solution 5; a vacuum pump 15 as a mechanism for evacuating the plating tank 11 or introducing an inert gas; and a plating tank 11 17g valve provided in the pipe between pump and pump 15
A plating solution tank 16 as a mechanism for selectively supplying, circulating, and discharging a plating solution and a cleaning solution to the gas inlet 20 and the gas pipe 23, the plating tank 11, and circulating and discharging, and the valves 17a, 17b, 17c,
17d, 17e, and 17f, a supply port 21, a discharge port 22, and a pipe 24 for the cleaning liquid.

In FIG. 2, first, the valves 17a, 17b, 17c, 17d, 17e, 17f
The plating solution is put in the plating solution tank 16 with the closed. A member to be plated 12 serving as a cathode inside a plating tank 11,
An anode plate 13 made of indium is arranged to face. The plating tank 11 is an airtight container that can maintain airtightness. Subsequently, valve 17a,
17c is opened, and the plating liquid is introduced from the plating liquid tank 16 in the directions of arrows 19d, 19a, and 19b by the liquid feed pump 14, and the plating power is supplied.
A current is applied from 18 to the member to be plated 12 as shown in FIG.
Then, an In plating bump 6 is formed as shown in FIG. Next, valve 17
g is switched, and an inert gas is introduced into the plating tank 11 from the gas inlet 20 as indicated by an arrow 19h. Subsequently, the valves 17a and 17c are closed, the valves 17e and 17b are opened, and the plating solution 5 is supplied to the plating solution tank 16
Then, the valves 17e and 17b are closed, the valves 17d and 17f are opened, and pure water is supplied as a cleaning liquid from the supply port 21 by a liquid feed pump, and the plate 12 and the anode plate 13 are cleaned and discharged to the discharge port 22. I do.
After this cleaning, the plating tank 11 is opened in an inert gas atmosphere,
The member to be plated 12 is taken out. This ends the production.

Here, the inert gas is not necessarily limited to Ar, Ne or the like, and may be any gas having a low reactivity such as nitrogen. Also plating tank
If the inside of the tank is evacuated in advance by a vacuum pump 15 before introducing the inert gas into 11, the replacement of the atmosphere in the tank is more effective.

In the method of the present invention, no oxide film is formed on the surface of the In plating bump 6 because there is no contact with the atmosphere.

The above embodiments are merely examples, and it goes without saying that the present invention can be similarly applied to bump plating other than indium.

〔The invention's effect〕

As described above, according to the electroplating method and plating apparatus of the present invention, after electroplating, cleaning and removal in an inert gas atmosphere prevent surface oxide film formation after plating film formation, and provide sufficient thermocompression bonding. Can be formed.

[Brief description of the drawings]

1 (a) and 1 (b) are enlarged cross-sectional views showing a process of forming an In-plated bump to which the electroplating method of the present invention is applied, and FIG. 2 is an embodiment of a plating apparatus used to carry out the process. FIG. 3 is a partial sectional view showing an example, and FIG. 3 is a view showing an In bump by a conventional method. DESCRIPTION OF SYMBOLS 1 ... Substrate 2, Plating base metal 3 ... Resist film 4, ... Opening 5 ... Plating solution, 6 ... In plating bump 7 ... Oxide film, 11 ... Plating tank 12 ... Plating target Member 13 Anode plate 14 Liquid pump 15 Vacuum pump 16 Plating solution tank 17a, 17b, 17c, 17d, 17e, 17f, 17g Valve 18 Plating power supply 19a, 19b 19c, 19d, 19e, 19f, 19g, 19h …… Arrow 20 …… Gas inlet, 21… Supply port 22 …… Discharge port, 23… Gas piping 24 …… Piping

Claims (2)

(57) [Claims] An electroplating process is performed by supplying a plating solution to a plating tank in which a member to be plated and an anode plate are opposed to each other, and the plating solution is discharged in an inert gas atmosphere. An electroplating method comprising supplying a cleaning liquid to clean the member to be plated, and then removing the member to be plated while maintaining an inert gas atmosphere. 2. A plating tank having therein an anode plate arranged to face a member to be plated and capable of being sealed by filling a plating solution, and a mechanism for evacuating the plating tank or introducing an inert gas. And a mechanism for switching, supplying, circulating, and discharging a plating solution and a cleaning solution to and from the plating tank.