JPH05109657A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the dispersion in a plating film thickness by avoiding the oxidation of a barrier metal serving both as a plating conductive path for lowering the resistor as the conductive path in order to form wirings by an Au plating process. CONSTITUTION:An oxide film 3 is formed on a semiconductor substrate 1 having a plurality of element regions 2 after finishing the diffusing step to form aperture parts for contact. Next, a barrier metal 4 and a thin Au film 5 are successively deposited. Next, a photoresist 7 having aperture parts 6 in the regions to form the Au wirings is formed. Finally, the whole body is immersed in a plating solution to feed a plating current so that Au plated films 9 to be the wiring patterns may be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring forming method using a gold plating method.

[0002]

2. Description of the Related Art A conventional wiring forming method by gold plating will be described with reference to FIG.

First, an opening for contact is formed in the oxide film 3 on the surface of the semiconductor substrate 1 after the diffusion process.
Next, a barrier metal 4 with good adhesion to the oxide film 3 and gold
Are deposited by a sputtering method or the like. Next, the photoresist 7 which covers other than the wiring pattern is patterned. Next, the plating electrode 8 is connected to one end of the barrier metal 4 and immersed in a plating solution to apply a voltage. Using the photoresist 7 as a mask, the gold plating film 9 is formed only on the wiring pattern. At this time, titanium or titanium and platinum are often used for the barrier metal 4 in order to prevent gold of the gold plating film 9 from entering the semiconductor substrate 1.

[0004]

In order to prevent gold from penetrating into the semiconductor substrate and to maintain adhesion with the oxide film, titanium, molybdenum, a stack of titanium and platinum is used as the barrier metal.

This barrier metal has a relatively high resistivity, and when a wiring pattern is opened by forming a photoresist after depositing a semiconductor substrate except platinum, a slight oxide film is formed to further improve the resistance. The rate becomes high.

[0006] Even in platinum, a state in which the resistivity is considerably high often occurs depending on the crystalline state.

When a photoresist is patterned on such a semiconductor substrate and the opening is plated, the resistance of the barrier metal, which plays the role of a conductive path for plating, is large.
The potential is slightly different between the portion near the plating electrode and the portion far from the opening. Different plating rates often cause variations in the thickness of the plated film. Therefore, there is a problem in that the electrical characteristics between the elements vary.

[0008]

According to a method of manufacturing a semiconductor device of the present invention, a step of depositing a metal film having good adhesion on one main surface of a semiconductor substrate and forming a gold thin film on the surface of the metal film. A step of selectively gold-plating the gold thin film to form a wiring pattern of a low-resistance gold plating film; and etching the gold thin film and the metal film using the gold plating film as a mask And a process.

[0009]

EXAMPLE FIG. 1A shows a first example of the present invention.
This will be described with reference to (c).

First, as shown in FIG. 1A, an oxide film 3 is formed on a semiconductor substrate 1 having a plurality of element regions 2 and subjected to a diffusion process, and an opening for contact is formed.

Next, it is put in a sputtering apparatus and a thickness of 200
A barrier metal 4 made of molybdenum of 4 nm is sputtered. Molybdenum has three functions: a conductive path for plating, an adhesive between gold and an oxide film, and prevention of gold from entering the semiconductor substrate.

Next, after depositing a thin gold film 4 having a thickness of 50 nm continuously in the same sputtering apparatus, it is taken out from the sputtering apparatus.

Next, as shown in FIG. 1B, a photoresist 7 having an opening 6 is formed in a region where a gold wiring is to be formed.

Next, as shown in FIG. 1C, the gold plating film 9 is formed by immersing in a plating solution and applying a plating current to form a wiring pattern.

Next, a second embodiment of the present invention will be described.

In this embodiment, as shown in FIG. 1A, the barrier metal 4 is formed on the semiconductor substrate 1 and then taken out from the sputtering apparatus. Next, as shown in FIG.
Are connected to each other and are immersed in the plating solution 10 together with the counter electrode 11, and a strong electric field is applied by the plating power source 12 to perform strike plating to form the thin gold film 5 shown in FIG. After that, the same steps as those in the first embodiment are performed, and
The gold plating film 9 shown in (c) is formed.

[0017]

EFFECTS OF THE INVENTION Before forming a photoresist to be a wiring pattern on a barrier metal, a thin gold film is formed in advance. Therefore, the barrier metal can be prevented from being oxidized and the increase in resistivity can be suppressed. In addition, since the thin gold film has a low resistivity, the resistivity as a conductive path for plating can be significantly reduced.

As a result, the potential difference between the gold plating wiring patterns becomes very small, and a uniform gold plating layer can be realized. Therefore, it is possible to suppress variations in electrical characteristics between elements.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in process order.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a wiring forming method by a conventional gold plating method.

[Explanation of symbols]

 1 Semiconductor Substrate 2 Element Area 3 Oxide Film 4 Barrier Metal 5 Thin Gold Film 6 Opening 7 Photoresist 8 Plating Electrode 9 Gold Plating Film 10 Plating Solution 11 Counter Electrode 12 Plating Power Supply

Claims (1)

[Claims] 1. A step of depositing a metal film having good adhesion on one main surface of a semiconductor substrate, a step of forming a gold thin film on the surface of the metal film, and a step of selectively plating the gold thin film with gold. A method of manufacturing a semiconductor device, comprising: a step of forming a wiring pattern made of a low resistance gold plating film; and a step of etching the gold thin film and the metal film using the gold plating film as a mask.