JPH05243183A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To restrain a plating film from varying in thickness by a method wherein a wafer is placed on a wafer holder composed of a ring-shaped insulator and conductive holder pieces electrically isolated from each other, and currents are separately fed to the holder pieces. CONSTITUTION:A wafer holder 1 is composed of holder pieces 1a, 1b, and 1c and a ring-shaped insulating 1d which electrically isolates the holder pieces 1a, 1b, and 1c. The holder pieces 1a, 1b, and 1c are separately connected to current power sources 9a, 9b, and 9c with copper wires 5 respectively. An Si wafer 2 is held by pawls 3, coming into close contact with the wafer holder 1, and dipped into Au plating solution in a treating tank 8. A counter electrode 6 is made to serve as a positive electrode, constant currents are fed to the holder pieces 1a, 1b, and 1c respectively to carry out Au plating. By this setup, a current can be evenly fed throughout the wafer, so that, a plating film can be prevented from varying in thickness throughout the surface of the wafer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to an electrolytic plating method for forming electrodes such as Au electrodes of a semiconductor device.

[0002]

2. Description of the Related Art A conventional Au plating method will be described with reference to FIG. The Si wafer 2 to be plated is brought into close contact with the copper wafer holder 10 by the pawl 3 made of a fluorine resin such as polytetrafluoroethylene attached to the holder. The wafer holder 10 is connected to the constant current power source 9 by the copper wire 5. Further, the wafer holder 10 and the copper wire 5 are
Except for the part where the wafer is in close contact, it is coated with a fluororesin 4.

The wafer holder 10 holding the Si wafer 2 is immersed in the Au plating solution 7 in the processing bath 8. In the Au plating liquid 7, a counter electrode 6 made of platinum and connected to a constant current power source 9 is arranged so as to face the Si wafer 2.

In this device, 0.4 A / dm ² (1
When a current is applied at a current density of 0.1 m), Au is plated on the wafer 2 at a rate of about 2000 Å / min.

[0005]

In the conventional plating method described above, the current concentrates on the peripheral portion of the wafer 2, so that the plating film thickness varies significantly. That is, as shown in FIG. 4, when Au plating having a film thickness of 1.2 μm is applied around the wafer, the film thickness at the center of the wafer becomes 0.6 μm.

[0006]

According to the method of manufacturing a semiconductor device of the present invention, one to a plurality of ring-shaped insulators and a plurality of conductive layers electrically isolated from each other by the ring-shaped insulators. A wafer is placed on a wafer holder composed of holder pieces, and electrolytic plating is performed while supplying current to each holder piece independently.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. 1A is a schematic cross-sectional view of a plating bath used in one embodiment of the present invention, and FIG. 1B is a plan view of a wafer holder used in this embodiment. The wafer holder 1 is composed of copper holder bodies 1a, 1b, 1c and a ring-shaped insulator 1d that electrically separates them.

Each holder element body 1a, 1b, 1c is connected to a separate constant current power source 9a, 9b, 9c by a copper wire 5, respectively. The portion of the wafer holder 1 excluding the lower surface and the portion of the copper wire 5 which is immersed in the plating solution are coated with a fluororesin 4. The Si wafer 2 is brought into close contact with and held by the wafer holder 1 by the pawl 3, and is immersed in the Au plating solution 7 in the processing bath 8.

In the Au plating solution 7, a counter electrode 6 made of platinum is arranged at a position facing the Si wafer 2. The counter electrode 6 is connected to each constant current power supply 9a, 9b, 9c. With the counter electrode 6 as the positive electrode side, a constant current power source 9a,
A constant current is supplied to each holder element 1a, 1b, 1c by 9b, 9c to perform Au plating.

0.4 A / dm for each holder element
The plating film thickness on the wafer when performing plating by supplying current at a ^second current density is shown in FIG. As shown in the figure, according to this example, the plating film thickness could be set within the range of 0.9 to 1.1 μm on the entire surface of the wafer.

If the plating film thickness varies within the same holder piece, the holder piece may be further divided. Further, when the film thickness varies between the holder pieces, for example, the constant current to the holder piece in the portion where the film thickness is insufficient may be increased.

In the above embodiment, a DC constant current was supplied to each holder element, but this can be replaced with a pulse current. Further, the present invention can be applied to plating other than Au plating.

[0013]

As described above, according to the method of manufacturing a semiconductor device of the present invention, a wafer is held in a wafer holder composed of a ring-shaped insulator and holder pieces separated by the insulator, and each holder piece is held. Since the plating is performed while supplying the current independently, according to the present invention, the current can be uniformly supplied over the entire surface of the wafer and the variation in the plating film thickness due to the position can be suppressed. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a plating apparatus for explaining an embodiment of the present invention and a plan view of a wafer holder used in this embodiment.

FIG. 2 is a plating film thickness distribution diagram showing the effect of the present embodiment.

FIG. 3 is a schematic sectional view of a plating apparatus for explaining a conventional example.

FIG. 4 is a plating film thickness distribution diagram obtained by a conventional example.

[Explanation of symbols]

 1, 10 Wafer holder 1a, 1b, 1c Holder piece 1d Insulator 2 Si wafer 3rd 4 Fluorine resin 5 Copper wire 6 Counter electrode 7 Au plating solution 8 Treatment tank 9, 9a, 9b, 9c Constant current power supply

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Claims (1)

[Claims] 1. A wafer holder is mounted on a wafer holder including one to a plurality of ring-shaped insulators and a plurality of conductive holder pieces electrically separated from each other by the ring-shaped insulators. And a method of manufacturing a semiconductor device, wherein electrolytic plating is performed while supplying electric current to each holder piece independently.