JPS60128615A - Electrolyte plating method for semiconductor wafer - Google Patents

Abstract

PURPOSE:To prevent contact between wafer and electrolyte and to supply a voltage to a metal plate by closely placing in contact the rear surfaces of two sheets of semiconductor wafers holding said metal plate between them. CONSTITUTION:The rear surfaces of two sheets of n type silicon wafers S are closely placed in contact each other through a metal place C and thereby protected from contact with the electrolyte. In order to protect the side surfaces of silicon wafers S from electrolyte, a small amount of film M is attached. A voltage is supplied to a metal plate C. Thereby, the n type region of silicon wafer S, p-n junction just below the surface, p type region at the surface and a current path which reaches the electrode A through electrolyte are respectively formed and the electrolyte plated layer is further formed in the p type region at the surface. As a metal plate C, a soft metal having high expandability such as indium and gold is just suitable in order to obtain excellent electrical contact with the silicon wafer S.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for electrolytic plating of semiconductor wafers.

When performing electrolytic plating by passing a current through a pn junction to the p-type head region on an n-type semiconductor wafer, it is necessary to prevent the back surface of the n-type semiconductor wafer from coming into direct contact with the electrolyte. This is because the existence of a diffusion potential in the pn junction makes it difficult for current to flow through the p-type portion compared to the n-type portion on the back surface. Similarly, when performing electrolytic plating on an n-type region on an n-type semiconductor wafer, it is necessary to prevent the back surface of the p-type semiconductor wafer from coming into direct contact with the electrolyte.

Conventionally, as shown in FIG. 1, the back surface of a semiconductor wafer S has been covered with an insulating film M, but in order to cover the entire back surface, a large amount of film forming material is required, which not only increases cost. There was a problem in that pinholes were formed in the coating and the effectiveness of the coating was likely to be lost.

The present invention has been made in view of the above-mentioned conventional problems,
The purpose is to provide a method for electrolytic plating of semiconductor wafers that is low cost and has a high yield.

To achieve the above object, the present invention is configured such that the back surfaces of two semiconductor wafers are brought into close contact with each other by sandwiching a metal plate to prevent contact with an electrolyte and to supply voltage to the metal plates. There is.

The present invention will now be explained in more detail by way of examples.

FIG. 2 is a sectional view for explaining one embodiment of the present invention. S is an n-type silicon wafer.

A plurality of p-wall regions separated by insulating films I made of silicon dioxide or the like are formed on the surface thereof. C is a metal plate, A is an electrode 2M is a coating.

- The back surfaces of the two n-type silicon wafers S are brought into close contact with each other via the metal plate C, thereby preventing contact with the electrolyte. A small amount of coating M is added to prevent contact between the silicon wafer S and the electrolyte on the side surfaces. metal plate C
is supplied with voltage.

From here, pn immediately below the surface of n-type region 2 of silicon wafer S
A current path is formed through the p-type W4 region on the surface of the junction 2 and the electrolytic solution to the electrode A, and an electrolytic plating layer is formed on the p-wall region on the surface 1.

As the metal plate C, in order to improve the electrical contact with the silicon wafer S, Injum or a soft metal with high ring extensibility is suitable. Further, as the film M, a wax or the like having high resistance to the plating solution and high adhesiveness in order to increase the adhesion strength between the silicon wafer S and the metal plate C is suitable. This film M is.

After electrolytic plating is completed, it is removed by heating or by using a solvent.

Further, the silicon wafer S or the electrode A may be rotated to eliminate uneven plating as necessary.

As explained above, according to the present invention, there is no need to coat the back surface of the semiconductor wafer, so there is an advantage that the amount of coating material used is small and the cost is low.

Furthermore, since only a small area on the side surface of the wafer needs to be coated, pinholes are less likely to be formed and the yield is improved.

Furthermore, the present invention has the advantage that two semiconductor sheets can be electrolytically plated at the same time, so that one working time can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining a conventional method, and FIG. 2 is a sectional view for explaining an embodiment of the present invention. S...Silicon wafer, C...Metal plate 1M...1J covered,
! ...Silicon dioxide, A...Electrode.

Claims (1)

[Scope of Claims] A first surface that is contacted with an electrolyte to form a plating layer, and a second surface that is supplied with a voltage and shielded from the electrolyte during the formation of the plating layer. In an electrolytic plating method for semiconductor wafers. The second side of the two semiconductor wafers is completely processed.