JPH0626212B2 - Method for manufacturing semiconductor device - Google Patents

Description

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device made of a refractory metal or a silicide thereof.

[Prior Art] Conventionally, the step of depositing a refractory metal or its silicide (hereinafter referred to as silicide) and the subsequent heat treatment step are performed independently of each other. The surface of a semiconductor made of a melting point metal or its silicide may be exposed to the atmosphere.

FIGS. 3A and 3B are cross-sectional views of a semiconductor chip showing the order of steps for explaining an example of a conventional method for manufacturing a semiconductor device.

In this conventional example, first, as shown in FIG. 3 (a), a titanium layer 4a 'is first formed on an oxide film 2 and a polycrystalline silicon film 3 which are sequentially formed on a silicon substrate 1 and then once in the atmosphere. Therefore, an oxide layer 6 is formed on the surface of the titanium layer 4a '.

Next, as shown in FIG. 3 (b), heat treatment is performed with the oxide layer 6 still attached, so that the polycrystalline silicon film 3 and the titanium layer 4 are formed.
The titanium silicide layer 4'is formed by reacting with a '.

In this case, because of the presence of the oxide layer 6 on the surface, the titanium silicide layer 4'is non-uniform and the layer resistance is high.

[Problems to be solved by the invention]

In the above-described conventional method for manufacturing a semiconductor device, the step of depositing the refractory metal or its silicide and the subsequent heat treatment step are performed independently, and the semiconductor substrate is exposed to the atmosphere during the process. An oxide layer is formed on the surface of the silicide, or impurities are attached to the surface of the silicide, so that the conductor layer made of the refractory metal or the silicide is nonuniform and the layer resistance is high.

Further, when the surface of the conductor layer is treated with hydrofluoric acid before the heat treatment, titanium is also removed at the same time.

[Means for solving problems]

A feature of the present invention is that at least a unit step of forming a conductor layer by depositing a refractory metal or a silicide thereof on a semiconductor substrate and then performing short-time heat treatment by lamp annealing in a vacuum or in an inert gas atmosphere. A semiconductor device that includes once and holds the semiconductor substrate in a vacuum or a non-oxidizing gas atmosphere without exposing the semiconductor substrate to the atmosphere during the unit process and from the unit process to the unit process for the entire period. In the manufacturing method.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

1A to 1C are cross-sectional views of a semiconductor chip shown in the order of steps for explaining the first embodiment of the present invention.

In this embodiment, first, as shown in FIG. 1A, a 500 Å oxide film 2 and a 3000 Å polycrystalline silicon film 3 are sequentially formed on a silicon substrate 1.

Next, as shown in FIG. 1B, the polycrystalline silicon film 3
After the surface of the above is treated with hydrofluoric acid to remove the oxide film formed in the atmosphere, a titanium layer 4a of 500 Å is formed by a vacuum evaporation method.

Next, as shown in Fig. 1 (c), 800 times was continuously applied in a vacuum by a halogen lamp annealing method without being exposed to the atmosphere.
The titanium silicide layer 4 is formed by heating at ℃ for 15 seconds.

2A and 2B are cross-sectional views of the semiconductor chip shown in the order of steps for explaining the second embodiment of the present invention.

In this embodiment, first, as shown in FIG. 2 (a), an oxide film 2 and a polycrystalline silicon film 3 are sequentially formed on a silicon substrate 1 and then the surface of the polycrystalline silicon film 3 is treated with hydrofluoric acid. Then, a tungsten silicide layer 5a made of WS _3.5 having a composition ratio of tungsten and silicon of 1: 3.5 is formed to a thickness of 1000 Å by a sputtering method. Then, the silicon substrate 1 is heated at 1000 ° C. for 10 seconds by a halogen lamp annealing method in vacuum without exposing it to the atmosphere. Here, the reason why the tungsten silicide having a large silicon composition ratio is first deposited is to improve the adhesion with the lower polycrystalline silicon layer 3.

However, since the layer resistance of the tungsten silicide layer 5a is high, the surface of the tungsten silicide layer 5a on the semiconductor substrate 1 is continuously exposed without being exposed to the atmosphere, as shown in FIG.
As shown in, the composition ratio of tungsten and silicon is 1: 1.
A tungsten silicide layer 5b made of WS _1.8 having a large composition ratio of 8 and tungsten is formed to a thickness of 1000 Å by a sputtering method. Further, it is heated in vacuum by a halogen lamp annealing method at 1000 ° C. for 10 seconds.

Thus, a low-resistance tungsten silicide layer can be formed, and the semiconductor substrate is never exposed to the atmosphere in the series of steps of depositing the silicide layer and heat treatment, so that a high-purity tungsten silicide layer can be obtained.

In this embodiment, the lamp annealing is performed every time each silicide layer is deposited, but it goes without saying that the lamp annealing may be performed after depositing the entire silicide layer first.

〔The invention's effect〕

As described above, in the present invention, the deposition of the refractory metal or its silicide and the heat treatment are performed in a series of vacuums, and the surface of the semiconductor substrate is not exposed to the atmosphere during the process, so that the contamination from the atmosphere is prevented. In addition, the formation of an oxide layer on the surface of the refractory metal or its silicide can be prevented, and a uniform conductor layer having a low layer resistance can be stably obtained.

[Brief description of drawings]

FIGS. 1A to 1C and FIGS. 2A and 2B are cross-sectional views of a semiconductor chip showing the order of steps for explaining the first and second embodiments of the present invention, respectively. Figure 3 (a),
(B) is sectional drawing of the semiconductor chip shown in order of process for demonstrating an example of the manufacturing method of the conventional semiconductor device. 1 ... Silicon substrate, 2 ... Oxide film, 3 ... Polycrystalline silicon film, 4, 4 '... Titanium silicide layer, 4a, 4
a '... titanium layer, 5a, 5b ... tungsten silicide layer, 6 ... oxide layer.

Claims (1)

[Claims] 1. A unit process of forming a conductor layer by depositing a refractory metal or a silicide thereof on a semiconductor substrate and then performing short-time heat treatment by lamp annealing in a vacuum or in an inert gas atmosphere to form a conductor layer. Including the above, the semiconductor substrate is kept in a vacuum or in a non-oxidizing gas atmosphere without being exposed to the atmosphere during the unit process and from the unit process to the unit process over the entire period. And a method for manufacturing a semiconductor device.