JPS59121925A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a barrier layer to enable to attain stable contact between a substrate and a metal wiring at a semiconductor device by a method wherein the silicide of a high melting point metal is deposited on an n<+> type semiconductor region according to the sputtering method, and the silicide film is annealed at a high temperature to be silicified completely. CONSTITUTION:PSG is applied on the whole surface of a substrate 1 containing an n<+> type diffusion layer 2, anisotropic etching is performed to the PSG film 3 to form a contact hole in the vertical direction, and the film is molten to round off the corners. A molybdenum film 4 is formed as the primary stage of formation of a barrier layer, while the film 4 thereof is in the amorphous condition. A silicified molybdenum silicide film 4' is formed. To perform silicification, the silicide film 4 is annealed at the the high temperature of about 600- 900 deg.C in an atmosphere such as nitrogen, hydrogen, argon or a vacuum. An aluminum thin film 5 is formed according to evaporation, and the aluminum film thereof and the molybdenum silicide film 4' are patterned to form an IC.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more specifically, to an ohmic connection between an n+ semiconductor region, such as n+ silicon, and a metal interconnect, such as aluminum/silicon. Concerning how to improve contact. The present invention is effective in stabilizing contact resistance.

(2) Prior Art and Problems It is well known that various techniques are used to obtain ohmic contact between a substrate and metal wiring in semiconductor devices. Many of these known methods typically employ a structure in which polycrystalline silicon, aluminum/silicon, or aluminum/lambda metal wiring is placed on a diffusion layer (n+ semiconductor region) of a semiconductor substrate. However, with such a structure, the resulting contact resistance is unstable. This is because, for example, when looking at the contact between n-silicon and aluminum/silicon, the silicon contained in the aluminum/silicon precipitates on the n-silicon and causes a slight but unfavorable chemical reaction. .

In order to eliminate the instability of contact resistance as described above, a suitable barrier layer (
Conventionally, it has been proposed to interpose a barrier metal (barrier metal). Useful barrier metals include, for example, platinum silicide, .) radium silicide, and the like. Although this improved method can be advantageously used at relatively low temperatures, e.g. below 400°C, it can be used at higher temperatures commonly used in the art, e.g.
It is unsuitable at high temperatures of 50°C, 500°C or higher. This is because if the above-mentioned silicide is placed under the aluminum/silicon wiring, an undesirable chemical reaction will occur between the aluminum and the silicide, making the contact unstable. If the contact between the substrate and the metal wiring is unstable, i.e.
As the contact resistance deteriorates, the voltage decreases and therefore,
This is undesirable because the speed changes and the initial access time shifts.

(3) Purpose of the Invention The purpose of the present invention is to provide an improved manufacturing method for a semiconductor device that enables stable contact between a substrate and metal wiring in order to prevent a lag in initial access time. shall be.

(4) Structure of the Invention The present inventor has recently discovered that when interposing a barrier layer at the interface between the diffusion layer and metal wiring of a substrate, a silicide film of a high melting point metal is sputtered onto the diffusion layer, that is, an n+ semiconductor region. It has been found useful to form a barrier layer by depositing the silicide film by a method and then annealing the amorphous silicide film at a high temperature of about 600 DEG to 900 DEG C. to completely silicide it.

Refractory metal silicides that may be advantageously used in the practice of the present invention are generally M2si, MSi and MSi2
(M in the formula is from group 4A, group 5A, and 6A of the periodic table)
metals belonging to the group), and specifically, Mo5t, WSi2゜TaS+2,'
r+S+2+others. These silicides
It can be used arbitrarily depending on the desired effect.

(5) Embodiments of the Invention Next, the method of the present invention will be explained with reference to the accompanying drawings. In this example, for the sake of convenience, a molybdenum silicide barrier layer that is placed under the aluminum wiring and subjected to high temperature annealing will be described.

In FIG. 1, reference numeral 1 denotes a p-type silicon substrate, which includes an n+ diffusion layer 2. As shown in FIG. An insulating film (here, phosphosilicate glass, ie, PSG) having a contact hole a is formed on the substrate 1 .

The PSG film 3 is produced by coating the entire surface of the substrate 1 with PSG, subjecting the formed PSG film to anisotropic etching to form vertically etched contact holes, and then melting the edges of the PSG film. It has a corner.

As a first step in forming the barrier layer, a molybdenum silicide film 4 as shown in FIG. 2 is formed.

This silicide film 4 is in an amorphous state and has not yet been converted into silicide. Such a silicide film can be formed by sputtering separate targets of molybdenum and silicon at the same time, or by depositing dimolybdenum silicide by sputtering using a mass of molybdenum silicide as a target.

The thickness of the silicide film 4 is preferably about 500X or less. Note that the conditions of the sputtering method used at this stage are not particularly limited.

Next, a silicided molybdenum silicide film 4' as shown in FIG. 3 is formed. Such silicidation is performed by forming the silicide film 4 at a high temperature of about 600-900° C. in an atmosphere such as hydrogen, argon or vacuum.
This can be done by annealing. When the heat treatment is performed at such a high temperature, the crystal grain size increases and the resistance decreases, and the resulting silicide film 4' is stable even at high temperatures.

Subsequently, as shown in FIG. 4, a thin aluminum film 5 of 1 μm in thickness is formed by vapor deposition, and this and a molybdenum silicide film 4' are patterned to fabricate an IC. In this case, surprisingly, aluminum and molybdenum silicide never react.

(6) Effects of the Invention According to the present invention, it is possible to obtain excellent ohmic contact between the substrate and the metal wiring, which does not lose stability even when exposed to high temperatures (450°C or higher). can. Therefore, according to the present invention, the initial access time lag can be avoided.

[Brief explanation of drawings]

FIGS. 1 to 4 each show a preferred method of the present invention.
It is a schematic cross-sectional view showing aspects in order. In the figure, 1 is a silicon substrate, 2 is an n+ diffusion layer, and 3 is PSG.
The film 4 is a molybdenum silicide film, and the film 5 is an aluminum thin film. Patent applicant Fujitsu Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate 1) Yukio Patent attorney Akira Yamaguchi

Claims (1)

[Claims] 1. Prior to metal wiring, apply high melting point metal silicide.
+ Deposited on the semiconductor region by sputtering method, and then deposited this amorphous silicide film with a thickness of about 60%.
A method for manufacturing a semiconductor device 0 characterized by annealing at a high temperature of 0 to 900°C