JPS5984441A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent failure of bonding between an insulating film as a diffusion layer protective film and a wiring metal by forming reaction product produced in process of forming of metal silicide on an insulating film arranged anew, followed by removal of said insulating film to remove reaction residuals. CONSTITUTION:An insulating film 12a is formed on a P typ semiconductor substrate 11 containing N type diffusion layer and a contact window is formed. Next an insulating film 13 is formed and top of the contact window is opened by use of photoresist 14. Then metal 15 for metal silicide is coated, followed by heat treatment to form metal silicide 16 at the contact window, after which the film 13 including reaction residuals in process of forming of metal silicide is removed by etching. Next, a wiring electrode 17, e.g. of Al is formed over the contact window having silicide 16, thereby preventing bonding failure of an insulating film and a wiring metal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming a metal silicide layer.

Examples of metal silicide-based Schottky type semiconductor devices and beam lead type semiconductor devices include metal silicide layers in the electrode extraction portions on the surface of the semiconductor substrate, and metal wiring electrodes arranged above the metal silicide layers. The manufacturing process from forming the metal silicide layer to arranging the electrode metal is usually performed in the following manner.

A semiconductor substrate including a diffusion layer and a thermal oxide film is covered with, for example, a CVD silicon nitride film as a protective film for the diffusion layer. Connection windows are opened in the thermal oxide film and the insulating film such as silicon nitride film using photoresist technology and chemical etching technology to form electrodes and protruding portions. For the purpose of forming metal silicide in the connection window, the silicide is thermally stable and easily forms with the substrate silicon. For example, a metal such as platinum is deposited by vapor deposition or sputtering,
After heat treatment in a nitrogen or argon atmosphere at ~800°C, unnecessary platinum outside the connection window (i.e., on the insulating film) is selectively chemically etched using heated aqua regia, etc. to remove only the platinum at the connection window. A metal silicide layer is formed. Furthermore, an electrode metal such as aluminum is deposited on the upper layer of the connection window having the metal silicide layer and is formed as a wiring electrode by PR technology or etching technology. It has been found that the following drawbacks occur during the forming process.

During heat treatment when forming a metal silicide layer, for example, a CVD nitride film as a protective film and platinum as a silicide layer form a reactant, and this reactant inherits and causes a reaction between the wiring metal and the formed metal silicide layer. This significantly reduces the adhesion and reduces the reliability of semiconductor devices.The formation of this reaction residue is particularly noticeable in protective films grown by CVD.This is because insulating films grown by CVD contain silicon particles, and these silicon particles and silicide This is because the forming metal reacts.

An object of the present invention is to solve the above-mentioned drawbacks related to poor adhesion between the ZETEN film and the wiring metal in the formation of metal silicide and wiring metal by elucidating the above-mentioned causes.

In the method for manufacturing a semiconductor device according to the present invention, a second insulating film is formed in advance before metal silicide formation, and a reactant for forming the metal silicide is formed on the second insulating film, and then the second insulating film is formed on the second insulating film. The method is characterized in that the insulating film is removed and a wiring metal layer is formed on a conventional insulating film free of reaction residues.

An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 11 is a P-type semiconductor substrate made of, for example, silicon, which includes an N-type diffusion layer, etc., and 12a is an insulating film made of CVD nitride film or the like as a protective film for the diffusion layer. . Connection windows are opened in the oxide film and the CVD nitride film by PR technology and etching technology to form electrode extraction parts (FIG. 1(a)). Thereafter, a second insulating film 13 is formed by, for example, film coating with a silicate film or the like and heat treatment, and a hole is formed above the connection window in the insulating film by a PR technique using a photoresist 14 or an etching technique. The opening window in the second insulating film is 1 to 2 microns larger than the lower connection window (FIG. 1(b)). After that,
A metal 15 such as platinum is deposited by vapor deposition or sputtering, and a metal silicide 16 is formed in the connection window through heat treatment at 400 to 800° C. in a nitrogen or argon atmosphere (Fig. 1(C)). ). Unnecessary platinum on the area other than the connection window, that is, on the second insulating film, is selectively chemically etched using, for example, aqua regia. Thereafter, the second insulating film containing reaction residues from the metal silicide formation is chemically etched away (FIG. 1(d)). Furthermore, sialuminum is deposited on the upper part of the connection window having the metal silicide layer, for example, by vapor deposition,
Form wiring electrodes using PR technology and etching technology (
Figure 1(e)).

With this manufacturing method, the reaction residue during metal silicide formation can be avoided by the newly placed second insulating film, and the problem of poor adhesion between the insulating film as a diffusion layer protective film and the wiring metal can be solved. It was possible to improve the reliability of a semiconductor device having metal wiring formed subsequent to metal silicide formation. Note that this embodiment is just one example, and is effective not only for forming wiring electrodes, but also for forming a protective film, etc., which is performed subsequent to metal silicide formation.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts according to an embodiment for explaining the manufacturing method of the present invention. In the figure, 11 is a P-type semiconductor substrate (including a diffusion layer), 12a.
...Thermal oxide film, 12b...Protective film for the diffusion layer, 13...Second insulating film, 13a...
- Second insulating film opening, 14... Photoresist, 15... Platinum tube o metal for metal silicide, 1
6...Metal silicide, 17... Indicates wiring electrode metal such as aluminum.

Claims (1)

[Claims] A metal silicide layer is formed on a semiconductor substrate in which a connection window for a first insulating film such as a thermal oxide film, a diffusion layer, a protective film, etc. has already been formed, and a second insulating film is first disposed. 1. A method of manufacturing a semiconductor device, which comprises: opening a hole in a second insulating film above a first insulating film opening, forming a metal silicide, and removing the entire surface of the insulating film.