JPS58161344A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To silicify a high melting-point metal in a section being in contact with silicon, and to simplify processes by forming a silicon thin-film onto an insulating film, coating the silicon thin-film with the high melting-point metal and thermally treating the whole in an oxygen atmosphere. CONSTITUTION:A silicon oxide film 22 is formed onto a silicon substrate 21 through a thermal oxidation method, and a polysilicon film 23 is formed onto the oxide film through a CVD method, and patterned through a photolithography process. A molybdenum film 24 is formed onto the polysilicon film 23 through magnetron sputtering, and thermally treated in the oxygen atmosphere, and a molybdenum silicide is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device in which low-resistance electrode wiring is formed using a high-melting point metal.

Conventionally, structures using polysilicon as electrodes and internal wiring materials have been widely used in semiconductor devices, especially semiconductor integrated circuits, but as miniaturization and higher integration progress, there is a demand for lower wiring resistance. A high-melting point metal or a compound of a high-melting point metal and silicon (hereinafter referred to as metal silicide), which has a larger resistance than polysilicon.
has been used as an electrode material. Among these, molybdenum silicide is often used, and an example of its formation method will be explained with reference to FIGS. 1fa) to 1(d+).

First, as shown in FIG. to adhere to.

Next, this is heat-treated at about 600° C. in a nitrogen-based atmosphere to cause the molybdenum film 14 and polysilicon film 13 to react,
As shown in FIG. 1(b), a molybdenum silicide film 1
form 5. At this time, if the polysilicon film 13 is sufficiently thick and the heat treatment time is sufficiently long, all of the molybdenum film 14 is turned into silicide, and a portion of the polysilicon film 13 remains.

A thin silicon oxide film 16 is still formed on the surface of the molybdenum silicide film 15 due to the reaction between the residual oxygen in the atmosphere and the silicon that has come from the polysilicon film 13 .

Next, as shown in FIG. 1[e], the silicon oxide film 16
A photoresist pattern 17 is formed thereon.

When this is subjected to plasma etching using a mixed gas of carbon tetrafluoride and oxygen, as shown in FIG. Because of the small size, an eave-like protrusion 18 may be formed on the silicon oxide film 16.

If such a protrusion 18 exists, a problem arises in that when a thin film is formed on the protrusion 18, the layer is not sufficiently coated and a portion of the underlying layer is exposed.

Furthermore, since the etching rates of the molybdenum film 14 and the molybdenum silicide film 15 are generally different, the batten edge may be distorted at the interface between the molybdenum silicide film 15 and the polysilicon film 13, resulting in distortion 19. In this case as well, problems such as deterioration of the adhesion of the thin film formed thereon arise.

These problems stem from the fact that the molybdenum silicide film formed by this method has a multilayer structure and that the etching characteristics of each film are generally different.5 This problem can be solved by etching the films individually, but in that case the process becomes complicated.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a method for manufacturing a semiconductor device that can easily form a silicide film of a high melting point metal and pattern it.

Embodiments of the method for manufacturing a semiconductor device of the present invention will be described below with reference to the drawings. Figure 2(a) to Figure 2f
c) is a process explanatory diagram of one example.

First, as shown in FIG. 2(a), a silicon oxide film 22 as an insulating film is formed on a silicon substrate 21 by thermal oxidation.
A rough silicon film 23 having a thickness of about 300 OA is formed thereon by the CVD method, and patterning is performed by a normal photolithography process.

Next, as shown in FIG. 2 tbl, the polysilicon film 13
A molybdenum film 24 of about 300 OA is formed thereon by magnetron sputtering.

Next, when this is heat-treated at 900° C. for about 30 minutes in an oxygen atmosphere, the molybdenum film 2 on the polysilicon film 13 is
4 reacts, and as shown in FIG. 2(c), the molybdenum silicide film 25 and the molybdenum film 24 on the silicon oxide film 22 become molybdenum oxide and evaporate. In this way, a metal silicon compound electrode is formed on the polysilicon film 23. Note that a silicon oxide film 26 is formed on the molybdenum silicide film 25.

As explained above, in the above embodiment, the molybdenum film 2
4 is in contact with the polysilicon oxide film 23,
A molybdenum silicide film 25 is formed, but the portions not in contact with the polysilicon oxide film 23 are not silicided.

In addition, the portions of the molybdenum film 24 not in contact with the polysilicon oxide film 23 are oxidized, and the molybdenum oxide film is vaporized at a relatively high vapor pressure ρ.

In the above embodiment, a thin film of polysilicon oxide film 23 was used to form molybdenum film 24 and silicide, but the same effect can be obtained if a single crystal silicon substrate or other silicon film is used.

A thin molybdenum film has been used as the high melting point metal film, but if the metal reacts with silicon to form a silicide and the metal oxide has a relatively high vapor pressure,
It has a similar effect.

As described above, according to the method of manufacturing a semiconductor device of the present invention, a silicon thin film is formed on an insulating film, a high-melting point metal is deposited on the silicon thin film, and the silicon is heat-treated in an oxygen atmosphere. The high melting point metal in the contact area is silicided, and the high melting point metal in the area not in contact with silicon is oxidized and vaporized to form a metal-silicon compound electrode, so etching of the high melting point metal film or silicide film is not necessary. There is no need to carry out this process, and a silicide film pattern is formed at the same time and in the same pattern as the silicon film pattern by heat treatment for silicidation of the high melting point metal film. Therefore, there are advantages in that problems associated with etching high-melting point metal films and silicide films are eliminated, and the process becomes easier.

[Brief explanation of drawings]

FIGS. 1(a) to 1(d) are process explanatory diagrams of a conventional method for forming a molybdenum silicide film electrode, respectively, and FIGS. 2(a) to 2fc) are manufacturing steps of a semiconductor device of the present invention, respectively. FIG. 2 is a process diagram of one embodiment of the method. 21...Silicon Y substrate, 22, 26...Silicon oxide film, 23...Polysilicon film, 24...Molybdenum film, 25...Molybdenum silicide film. Patent Applicant Oki Electric Industry Co., Ltd. Procedural Amendment August 31, 1980 Kazuo Wakasugi, Commissioner of the Japan Patent Office 1. Indication of Case 1981 Patent Application No. 42797 2. Name of Invention Method for Manufacturing Semiconductor Device 3. Relationship with the case of the person making the amendment Patent Applicant (029) Oki Electric Industry Co., Ltd. 4, Agent 5, Date of amendment order Showa year, month, day (self-motivated) 6, Part of drawing subject to amendment 7, Amendment Correct the content and lines as shown in red on the attached sheet.

Claims (1)

[Claims] A silicon thin film pattern is formed on the insulating film, a high melting point metal is deposited on the pattern, and heat treatment is performed in an oxygen atmosphere to silicide the high melting point metal in the part that comes into contact with the silicon thin film. 1. A method of manufacturing a semiconductor device, comprising: oxidizing and vaporizing a high-melting point metal in a portion that does not contain the metal, and forming a metal-silicon compound electrode on the silicon thin film.