JPH0669091B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a semiconductor device manufacturing technique and a technique particularly effective when applied to the formation of a Schottky barrier diode. For example, an electrode of an element in a semiconductor integrated circuit device. The present invention relates to a technique effectively used for forming a Schottky barrier diode made of aluminum silicide in the extraction portion.

[Background technology]

In a logic circuit such as a transistor-transistor-logic (TTL) circuit, a Schottky barrier diode (abbreviated as SBD) is formed between the base electrode and collector electrode of each transistor in order to speed up the circuit and reduce power consumption. It is well known to do.

For example, in a semiconductor integrated circuit device, a Schottky barrier diode is formed as follows. That is, a eutectic layer of aluminum and a semiconductor is formed in an electrode extraction portion of an element formed on a silicon semiconductor substrate, and a Schottky barrier diode is formed between the eutectic layer and the semiconductor. The eutectic layer is also called metal silicide, and a Schottky barrier is formed between the eutectic layer and the semiconductor.

However, in such a technique, the eutectic layer does not form a flat interface with the semiconductor, and a local penetration called a so-called alloy pit occurs, which causes characteristics such as the forward voltage φB of the Schottky barrier diode. It has been clarified by the present inventor that there is a problem that there is a large variation.

Further, the alloy pits that cause the above-mentioned variation are generated when an extremely thin natural oxide film is formed on the surface of the semiconductor and the reaction between aluminum and the semiconductor proceeds rapidly in the pinhole portion of the natural oxide film. The present inventor has revealed that the tendency of the alloy pit to occur is particularly remarkable when the metal is a metal having a relatively low melting point such as aluminum.

Due to the above problems, a Schottky barrier diode formed of a metal having a low barrier height, such as aluminum, in order to obtain desired characteristics has a large variation in its characteristics. It was difficult to obtain the characteristics described below with good reproducibility.

[Object of the Invention]

An object of the present invention is to provide a technique capable of reducing variation in characteristics of a Schottky barrier diode formed by using aluminum, for example.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[Outline of Invention]

The outline of a typical one of the inventions disclosed in the present application will be briefly described as follows.

That is, a platinum silicide film is formed between the main surface of the semiconductor substrate, aluminum wiring or aluminum-silicon wiring, and an aluminum alloy layer is formed between the platinum silicide film and the main surface of the semiconductor substrate. A Schottky barrier diode is formed at the interface between the semiconductor substrate and the aluminum alloy layer. With this structure, the occurrence of alloy pits can be prevented and the barrier height can be lowered, so a Schottky barrier with stable characteristics can be used.
A diode can be provided.

〔Example〕

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

In the drawings, the same or corresponding parts are designated by the same reference numerals.

First, FIG. 1 shows a main part of a semiconductor device formed by a manufacturing method according to the present invention.

The Schottky barrier diode shown in the figure is formed on a silicon semiconductor substrate 10 forming a semiconductor integrated circuit device. Then, a Schottky barrier diode using aluminum-silicon which is the second metal is formed in the electrode extraction portion of the element formed on the semiconductor substrate 10.

The surface of the semiconductor 10 is covered with an oxide insulating film 12. A part of the oxide insulating film 12 is opened, and a Schottky barrier diode is formed by using the opened part as an electrode extraction part.

In the opening, first, the semiconductor 10 and the first metal 14
A first eutectic layer 16 is formed by and which forms a flat interface with the semiconductor 10. In addition, the aluminum alloy 20 is formed by the semiconductor 10 and the second metal 18 along the interface between the first eutectic layer 16 and the semiconductor 10.
Are formed. A Schottky barrier is formed between the aluminum alloy 20 and the semiconductor 10.

Here, as the first metal 14, a metal having a relatively high melting point such as platinum is used. The eutectic layer (platinum silicide film) 16 formed by the metal having a high melting point, for example, platinum and the silicon semiconductor 10 is unlikely to have alloy pits unlike aluminum and the like, and has a flat interface with the semiconductor 10. Has become.

Further, when aluminum, which is often used as an electrode and wiring material of a semiconductor integrated circuit device, is used as the second metal 18, when the second metal 18 is directly reacted with the silicon semiconductor surface, the natural surface of the semiconductor surface is obtained. The alloy pits described above are generated due to pinholes in the oxide film. On the other hand, when aluminum-silicon is used as the second metal 18, a direct contact with the semiconductor surface raises the barrier. However, aluminum is used as the second metal 18 through the first eutectic layer 16 to form the first eutectic layer.
The transition between 16 and the semiconductor 10 forms an aluminum alloy 20 along the flat interface between the first eutectic layer 16 and the semiconductor 10. This allows aluminum alloy 20 and semiconductor
The interface with 10 is planarized along the flat interface between the first eutectic layer 16 and the semiconductor 10. As a result, the Schottky barrier diode formed with the aluminum alloy 20 does not generate alloy pits and has a barrier as low as a barrier between aluminum and a semiconductor, despite using aluminum-silicon. , The characteristics such as the forward voltage φB are less varied.

Next, a method of forming a Schottky barrier diode which is an embodiment of the present invention will be described in the order of steps based on FIGS. 2 to 5.

FIG. 2 shows a state in which the layer of the first metal 14 is provided on the silicon semiconductor substrate 10. The first metal 14 is platinum and is deposited (deposited) over the entire surface of the surface oxide insulating film 12 in which openings for taking out electrodes are formed.

FIG. 3 shows a state in which the first eutectic layer 16 is provided on the semiconductor substrate 10. After depositing the first metal 14 in FIG. 2, heat treatment is performed to form a first eutectic layer 16 between the first metal 14 and the semiconductor 10. Eutectic layer
Once 16 is formed, unreacted metal 14 is removed. This leaves only the first eutectic layer 16 as shown in FIG.

FIG. 4 shows a state in which a layer of the second metal 18 is provided on the first eutectic layer 16. This second metal 18 is a metal for forming a Schottky barrier diode,
Aluminum is used here. This second metal 18
Are deposited on the first eutectic layer 16. After this, heat treatment is performed, whereby the second metal 18
Through the first eutectic layer 16 to obtain the first eutectic layer 16.
16 is moved to the semiconductor 10 side below. And the first
An aluminum alloy 20 between the eutectic layer 16 and the semiconductor 10.
To form.

FIG. 5 shows the semiconductor device in which the aluminum alloy 20 is formed between the first eutectic layer 16 and the semiconductor 10. As shown in the figure, the first eutectic layer 16 is formed between the second metal 18 and the semiconductor 10, and the second metal 18 is formed between the eutectic layer 16 and the semiconductor 10. By partially transferring the first eutectic layer 16 to form the aluminum alloy 20, the aluminum alloy 20 is formed along the flat interface between the first eutectic layer 16 and the semiconductor 10. This makes aluminum alloy 20
And the semiconductor 10 are flattened along the flat interface between the first eutectic layer 16 and the semiconductor 10. As a result, the second
It is possible to form a Schottky barrier diode with good reproducibility between the metal 18 and the semiconductor 10 with a small variation in the characteristics such as the forward voltage φB.

〔effect〕

(1) By forming an aluminum alloy along the interface between the platinum silicide and the silicon substrate, alloy pits generated at the interface between the aluminum and silicon can be prevented, and at the interface between the aluminum-silicon and the silicon substrate. As compared with the barrier of (1), the barrier can be made lower, and variations in the characteristics of the Schottky barrier diode can be reduced, which is an effect.

(2) Higher performance and higher reliability of the semiconductor device can be achieved from (1).

Although the invention made by the present inventor has been specifically described based on the embodiments, the invention is not limited to the above-mentioned embodiments and can be variously modified without departing from the scope of the invention. Nor.

[Field of application]

In the above description, the case where the invention made by the present inventor is mainly applied to the technology for forming the Schottky barrier diode in the electrode extraction portion of the element in the semiconductor integrated circuit device which is the background field of application has been described. However, the present invention is not limited to this, and can be applied to, for example, a technique of forming a Schottky barrier diode as an independent element, and a method of manufacturing another semiconductor device having a Schottky junction.

[Brief description of drawings]

FIG. 1 is a sectional view showing a Schottky barrier diode manufactured according to an embodiment of the present invention, and FIGS. 2 to 5 are views for explaining the steps of the embodiment of the present invention. Is a cross-sectional view showing a state in which a semiconductor substrate is provided with a first metal layer, FIG. 3 is a cross-sectional view showing a state in which a semiconductor substrate is provided with a first eutectic layer, and FIG. FIG. 5 is a sectional view showing a state in which a second metal layer is provided on the eutectic layer, and FIG. 5 is a sectional view showing a state in which an aluminum alloy is provided between the first eutectic layer and the semiconductor. . 10 ... Silicon semiconductor substrate, 12 ... Oxide insulating film, 14 ...
First metal, 16 ... First eutectic layer, 18 ... Second metal,
20 …… Aluminum alloy.

Claims (1)

[Claims] 1. A part of wiring extending on one main surface of a silicon semiconductor substrate with an insulating film interposed therebetween contacts a region of one main surface of a semiconductor substrate through an opening formed in the insulating film. Then
A method of manufacturing a semiconductor device in which a Schottky barrier diode is formed at each interface between the wiring and the semiconductor substrate, wherein an insulating film is formed on one main surface of the semiconductor substrate, and a part of the insulating film is formed. A step of removing and forming an opening that exposes a region of the one main surface of the semiconductor substrate; a step of forming a platinum silicide film on the one region main surface of the semiconductor substrate in the opening; A wiring mainly composed of aluminum is formed on the insulating film and the insulating film, and a part of the aluminum of the wiring is transferred between the platinum silicide film and the semiconductor substrate through the platinum silicide film. Forming a Schottky barrier diode by forming aluminum silicide to be formed between the platinum silicide film and the semiconductor substrate. The method of manufacturing a semiconductor device, characterized in that.