JPS6262056B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to a semiconductor device having wiring made of different metals.

Conventionally, in order to prevent characteristic deterioration due to thermal reaction between the semiconductor substrate and electrode wiring in semiconductor devices,
There are many examples of using high melting point metals. In other words, the high melting point metal is interposed between the semiconductor substrate and the electrode wiring so that the two do not come into contact with each other. However, in such a semiconductor device, while deterioration due to thermal reaction between the semiconductor substrate and the main electrode wiring metal can be prevented, wiring resistance increases due to thermal reaction between the high melting point metal and the main electrode wiring metal. There are restrictions on the circuit configuration, and the wiring itself is thermally unstable. For example, titanium is used as the high melting point metal and aluminum is used as the main electrode metal, and the film thickness is adjusted accordingly.
In the case of 1000 Å and 2000 Å, when heat treatment is performed at a temperature of 450° C. for 1 hour, the layer resistance reaches nearly 8 times that of aluminum alone.

The present invention eliminates the drawbacks of such conventional devices, and
The purpose is to provide a thermally stable semiconductor device.

The present invention is characterized in that a first metal layer is formed on a semiconductor substrate, an insulating film having an opening is formed on the first metal layer, and the first metal layer is formed on the insulating film and in the opening. In the semiconductor device, a second metal layer having a lower melting point than the metal forming the metal layer is formed, and the first metal layer and the second metal layer extend in the same direction.

According to the present invention, since the electrode wiring is composed of a high melting point metal, an electrical insulating film provided with holes, and a main electrode metal, the reaction between the semiconductor and the main electrode metal and the reaction between the high melting point metal and the main electrode metal occur simultaneously. Therefore, an extremely stable semiconductor device can be obtained.

Next, in order to better understand the present invention, examples thereof will be described with reference to the drawings. To simplify the explanation, we will use the most commonly used material, ie, semiconductor silicon, and aluminum as the main electrode metal.

Figure 1a: Desired PN in silicon substrate 101
Junctions are formed, and elements such as transistors, diodes, and resistors are formed. Note that elements such as transistors are omitted in the figure for simplicity. It may also include a shot key barrier diode. Next, an electrical insulating film such as a silicon oxide film 102 is deposited on the silicon substrate 101 on which the device is formed, and an opening 103 is formed.

Figure 1b: Titanium 104 and silicon oxide film 106 as high melting point metals, each with a thickness of 1000 to 2000 Å,
It is deposited on the silicon oxide film 102 including the opening 103 to a thickness of 500 to 1000 Å.

FIG. 1c: Openings 107a, 107b in the silicon oxide film 106 that reach the titanium 104,
107c is provided. From the viewpoint of wiring resistance, these openings are preferably located at the same position as the opening 103, such as openings 107b and 107c.
but is not limited to this.

Figure 1 d: The openings 107a, 107b, 10
Aluminum 108 is deposited to a thickness of 0.3 to 1.0 μm on silicon oxide film 106 including silicon oxide film 7c. Next, the aluminum 108, the silicon oxide film 106, and the titanium 104 are selectively etched away using ordinary photolithography, and the aluminum 108 is removed by selective etching.
a, 108b and titanium 104a, 104b are formed to complete the electrode wiring.

Next, a second embodiment of the present invention will be described.

Figure 2a: Desired PN in silicon substrate 101
Junctions are formed, and elements such as transistors, diodes, and resistors are formed (elements are omitted in the figure). Next, an electrical insulating film, for example, a silicon oxide film 102 is deposited on the element formation surface of the silicon substrate 101,
An opening 103 is provided.

FIG. 2b: Titanium 104 and aluminum 201 as refractory metals are deposited on the silicon oxide film 102 including the openings 103, and then aluminum oxide 202 is provided on the aluminum 201. The thickness of each film is 1000 to 2000 for titanium 104.
Preferably, the aluminum 201 has a thickness of about 1000 Å, and the aluminum oxide 202 has a thickness of 500 to 1000 Å.

FIG. 2c: Openings 107a, 10 in the aluminum oxide 202 reaching the aluminum 201
7b and 107c are provided.

Figure 2 d: The openings 107a, 107b, 10
Aluminum 108 is deposited to a thickness of 0.3 to 1.0 μm on aluminum oxide 202 containing 7c. Next, using ordinary photolithography, the aluminum 108, aluminum oxide 202, aluminum 201 and titanium 104 are selectively etched away, and the aluminum 108a, 108b and 2
01a, 201b, aluminum oxide 202a,
202b and titanium 104a and 104b are formed to form electrode wiring.

Next, a third embodiment of the present invention will be described.

Figure 3a: Desired PN in silicon substrate 101
Junctions are formed, and elements such as transistors, diodes, and resistors are formed (elements are omitted in the figure). Next, an electrical insulating film, for example, a silicon oxide film 102 is deposited on the element formation surface of the silicon substrate 101,
An opening 103 is provided.

Figure 3b: Tantalum 301 as a high melting point metal
The silicon oxide film 10 including the opening 103
After depositing on tantalum 2, tantalum oxide 302 is provided on the tantalum 301. The tantalum oxide 302
can be formed by subjecting the tantalum 301 to anodizing treatment. The film thicknesses of the tantalum 301 and tantalum oxide 302 are each 1000 to 2000 Å.
is appropriate.

FIG. 3c: Openings 303a and 303b reaching the tantalum 301 are provided in the tantalum oxide 302.

FIG. 3d: Aluminum 108 is placed on the tantalum oxide 302 including the openings 303a and 303b.
A film thickness of 0.3 to 1.0 μm is applied. Next, using ordinary photolithography, the aluminum 108, tantalum oxide 302 and tantalum 301 are
Selectively remove aluminum 108a, 108
b, tantalum oxide 302a, 302b, and tantalum 301a, 301b are formed to form electrode wiring.

Note that FIG. 3e is a plan view of the above-mentioned electrode wiring.

In the above embodiment, titanium and tantalum were used as high melting point metals, but tungsten, titanium nitride, etc. can also be used. Further, as the electrical insulating film installed between metals, silicon oxide film, silicon nitride film, aluminum oxide film, etc. can be used, and as in the third embodiment, an oxide film of the metal is formed by anodizing. can also be used.

The present invention has been described above using examples, but the essential part of the present invention is that the electrode wiring of a semiconductor device is made of at least a metal film containing a high melting point metal, an electrical insulating film having openings, and a main electrode wiring metal. The object of the present invention is to simultaneously prevent deterioration of characteristics due to thermal reaction between the semiconductor and the main electrode wiring and an increase in wiring resistance due to thermal reaction between the high melting point metal and the main electrode wiring metal. That is, a major effect of the present invention is that a thermally stable semiconductor device can be obtained.

[Brief explanation of the drawing]

Figures 1a to 1d, Figures 2a to 2d
3a to 3d are cross-sectional views showing embodiments of the semiconductor device according to the present invention in the order of steps, and FIG. 3e is a plan view of the semiconductor device shown in FIG. 3d. In the figure, 101...silicon substrate, 102
...Silicon oxide film, 103...Silicon oxide film 10
2 openings, 104...Titanium, 104a, 104b
...Titanium forming electrode wiring, 106...Silicon oxide film, 107a, 107b, 107c...Opening in silicon oxide film 106 or aluminum oxide 202, 108...Aluminum, 108a, 108
b...Aluminum forming electrode wiring, 201...
Aluminum, 202...Aluminum oxide, 20
1a, 201b... Aluminum forming electrode wiring, 202a, 202b... Aluminum oxide forming electrode wiring, 301... Tantalum, 302... Tantalum oxide, 303a, 303b... Opening of tantalum oxide 302, 301a, 301b... Electrode wiring The tantalum to be formed, 302a, 302b... is tantalum oxide which forms the electrode wiring.

Claims (1)

[Claims] 1. A first insulating film having a first opening is formed on a semiconductor substrate, a first metal layer is formed on the first insulating film and within the first opening, and a first metal layer is formed on the first insulating film and within the first opening. A second insulating film having a second opening is formed on the metal layer, and a second metal having a melting point lower than that of the first metal layer is formed on the second insulating film and in the second opening. the first metal layer, the second insulating film, and the second metal layer have substantially the same shape, and the first metal layer and the second metal layer have substantially the same shape. 2. A semiconductor device characterized in that a portion other than the second opening is separated by the second insulating film.