JPS5827672B2 - Semiconductor device with electrodes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a semiconductor device having an electrode arranged at a predetermined position on a silicon semiconductor substrate in ohmic connection with the silicon semiconductor substrate.

In a conventional semiconductor device having such an electrode, the electrode is made of an aluminum layer placed on a silicon semiconductor substrate at a required position (hereinafter referred to as an electrode connection position) and directly connected to the silicon semiconductor substrate in an ohmic manner. was considered normal.

The reason for this is that the ohmic connection of the aluminum layer to the electrode connection position is made with a sufficiently low resistance compared to other metal layers, and that the electrode in a semiconductor device having this type of electrode is made of a silicon semiconductor. Generally, the structure is obtained by extending from the electrode connection position on the substrate to an insulating layer made of silicon oxide that extends around it, but in that case, if the electrode is an aluminum layer, the aluminum layer is obtained with good adhesion on the insulating layer, and the electrode in a semiconductor device having such an electrode is coated with a metal layer that can be extended to positions other than the electrode connection position on the semiconductor substrate. After that, the desired pattern is usually obtained by selectively etching the metal layer, but in that case, if the electrode is made of an aluminum layer, the metal layer is made of an aluminum layer. However, selective etching of the aluminum layer is relatively easy, and a wiring conductor may be bonded to the electrode in a semiconductor device having such an electrode.
In this case, when the electrode is made of an aluminum layer, there are many advantages such as bonding of a wiring conductor to the aluminum layer is relatively easy and the aluminum layer has excellent conductivity.

However, when the electrode in a semiconductor device having such an electrode is made of an aluminum layer, if the silicon semiconductor substrate is subjected to heat treatment for other purposes after the electrode made of the aluminum layer is formed, The only phenomenon is that the aluminum in the aluminum layer as an electrode reacts with the silicon in the region below the electrode connection position of the silicon semiconductor substrate due to the heat during heat treatment, and the aluminum invades the region under the electrode connection position of the silicon semiconductor substrate. For this reason, a semiconductor device having such an electrode may not have the desired characteristics, or a PN junction may be formed in the area below the electrode connection position of the silicon semiconductor substrate. In some cases, the PN junction is short-circuited, resulting in a semiconductor device having such an electrode being rendered unusable.

In addition, when a semiconductor device having such an electrode is actually used, the aluminum of the aluminum layer serving as the electrode is in the area below the electrode connection position of the silicon semiconductor substrate, and the silicon in the area under the electrode connection position of the silicon semiconductor substrate is The phenomenon of diffusion within the aluminum layer was observed, and as a result, the characteristics of semiconductor devices having such electrodes tended to change from the specified ones after long-term use. .

For this reason, conventionally, the electrode in a semiconductor device having this type of electrode is an electrode having a structure in which silicon is mixed into the aluminum layer as the electrode described above, and the aluminum layer as the electrode is locally The electrode is anodized, and the polycrystalline silicon layer is placed at the electrode connection position on the silicon semiconductor substrate in ohmic connection with the electrode, and the polycrystalline silicon layer is placed on the polycrystalline silicon layer in connection with the electrode. It has been proposed that the electrode be made up of an aluminum layer.

However, even if the electrode in a semiconductor device having this type of electrode has this configuration, the above-mentioned drawbacks when the electrode is made of an aluminum layer cannot be satisfactorily avoided.

Furthermore, conventionally, in order to avoid the above-mentioned drawbacks when the electrode in a semiconductor device having such an electrode is made of an aluminum layer, the electrode in a semiconductor device having such an electrode is made of a gold layer, a platinum layer, and a titanium layer. It has also been proposed to form an electrode with a three-layer structure.

However, even if the electrode has such a configuration, it is not possible to satisfactorily avoid the above-mentioned disadvantages when the electrode is made of an aluminum layer, as in the case described above, and the electrode is made of expensive metal. However, since it is constructed using conventional methods, it has disadvantages in terms of economy.

Therefore, it is an object of the present invention to propose a novel semiconductor device having such an electrode, which does not have the above-mentioned drawbacks. A platinum/silicide layer made of polycrystalline silicon as a matrix is placed in ohmic connection with the platinum/silicide layer, and a platinum/aluminum intermetallic compound layer is placed on the platinum/silicide layer in connection with the platinum/silicide layer. and an aluminum layer disposed on and connected to the platinum-aluminum intermetallic compound layer.Examples of the present invention will be described below in detail with reference to the drawings. It will become clearer.

FIG. 1 shows an embodiment of the present invention, in which a silicon semiconductor substrate 1
Required position indicated by code 2 above (electrode connection position)
There is an electrode 3 disposed in ohmic connection with this.

In this case, the silicon semiconductor substrate 1 includes, for example, a P-type silicon semiconductor layer 4 formed by, for example, an epitaxial growth method, and from the main surface 6 side of the silicon semiconductor layer 4 in order to form a PN junction 5 in the silicon semiconductor layer 4. An N-type semiconductor region I formed by diffusion of N-type impurities extends over the main surface 6 of the silicon semiconductor layer 4 to cover the end of the PN junction 5 reaching above the main surface 6, but the semiconductor region It has a structure consisting of an insulating layer 9 made of, for example, silicon oxide and having a window 8 formed so that the upper surface of the layer 7 is exposed to the outside.

Further, the electrode connection position 2 on the silicon semiconductor substrate 1 is located at a position facing the window 8 of the insulating layer 9 on the upper surface of the semiconductor region 7.

Further, the electrode 3 includes a platinum/silicate layer 10 made of polycrystalline silicon, which is arranged in ohmic connection with the electrode connection position 2 on the silicon semiconductor substrate 1, and a platinum/silicate layer 10 on the platinum/silicate layer 10. It has a structure consisting of a platinum-aluminum intermetallic compound layer 11 connected to the platinum-aluminum intermetallic compound layer 11, and an aluminum layer 12 connected to the platinum-aluminum intermetallic compound layer 11.

An electrode 3 consisting of a platinum-silicide layer 10, a platinum-aluminum intermetallic compound layer 11, and an aluminum layer 12, which is made of polycrystalline silicon that is actually cultivated in soil, is placed on an electrode connection position 2 on a silicon semiconductor substrate 1. A polycrystalline silicon layer is formed to a thickness that fits within the window 8 by a known method such as vapor deposition, and then a platinum layer is formed on the polycrystalline silicon layer by a known method such as vapor deposition or sputtering. is deposited to such a thickness that its upper surface does not protrude from the upper surface of the insulating layer 9, and then heat-treated to form a platinum-silicide layer consisting of a polycrystalline silicon layer and a platinum layer, and the polycrystalline silicon layer becomes a silicon layer. A length is formed so that no part of the platinum layer is left on the side of the electrode connection position 2 on the semiconductor substrate 1, and the platinum layer is not left behind. An aluminum layer is formed on the insulating layer 9 by a known vapor deposition or sputtering method, and then heat treated in the air or in a nitrogen gas atmosphere at a temperature of about 400"C for about 30 minutes. By this, PtAl2 formed by the aluminum layer and the platinum/silicide layer
．． PtA13. A relationship is obtained in which the platinum/aluminum intermetallic compound layer such as Pt2AA3 is left larger on the silicon semiconductor substrate 1 side than the aluminum layer is left on the silicon semiconductor substrate 1 side than the position inside the window 8, and the platinum/silicide layer is partially left on the silicon semiconductor substrate 1 side. The length to which the remaining relationships are obtained is obtained by forming and then or prior to selective etching of the remaining aluminum layer.

The above is an embodiment of a semiconductor device having an electrode according to the present invention. According to such a structure, the silicon semiconductor substrate 1
has a P-type semiconductor layer 4, an N-type semiconductor region 7, and a PN junction 5 between them, and the upper surface of the semiconductor region 7 is the electrode connection position 2 on the silicon semiconductor substrate 1. It is clear that the electrode 3 consisting of the platinum/silicide layer 10 with polycrystalline silicon as the base material, the platinum/aluminum intermetallic compound layer 11, and the aluminum layer 12 is arranged in the connection position 2 in an ohmic connection. Therefore, it is clear that the function as a semiconductor diode can be obtained, and therefore, the semiconductor device having the electrode according to the present invention described above in FIG. 1 can be said to be a semiconductor device having the electrode that can obtain the function as a semiconductor diode. However, in this case, the electrode 3 is ohmically connected to the electrode connection position 2 of the silicon semiconductor substrate 1, and is connected to the platinum/silicide layer 10 made of polycrystalline silicon as a matrix. Platinum-aluminum intermetallic compound layer 1 arranged as
1 and an aluminum layer 12 disposed thereon in connection with the aluminum layer 12. Therefore, even though the electrode 3 is constructed using the aluminum layer 12, the aluminum layer 12 is located at the electrode connection position of the silicon semiconductor substrate 1. Aluminum layer 1 is not directly ohmically connected to 2.
2 and the electrode connection position 2 of the silicon semiconductor substrate 1, a platinum-aluminum intermetallic compound layer 11 and a platinum-silicone compound layer 10 whose matrix is polycrystalline silicon are interposed, whereby the electrode 3 is formed. Even if the silicon semiconductor substrate 1 is subsequently subjected to heat treatment for other purposes, the aluminum of the aluminum layer 12 and the silicon in the region below the electrode connection position 2 of the silicon semiconductor substrate 1 may be damaged, as described at the beginning. I have no experience of the phenomenon of aluminum reacting and penetrating into the area below the electrode connection position 2 of the silicon semiconductor substrate 1, and when actually using a semiconductor device having the electrodes described above in FIG. As mentioned above at the beginning, the aluminum of the aluminum layer 12 diffuses into the area below the electrode connection amount 2 of the silicon semiconductor substrate 1, and the silicon of the area below the electrode connection position 2 of the silicon semiconductor substrate 1 diffuses into the aluminum layer 12. On the other hand, even if the platinum-silicide layer 10 made of polycrystalline silicon is directly ohmically connected to the electrode connection position 2 of the silicon semiconductor substrate 1, the silicon semiconductor The region below the electrode connection position 2 of the platinum/silicide layer 10 whose matrix is polycrystalline silicon and the silicon semiconductor substrate 1 is formed by heat treatment of the substrate 1 for another purpose. There is no unnecessary reaction with the silicon of the polycrystalline silicon, and therefore, there is a phenomenon that platinum/silicide based on polycrystalline silicon invades into the area below the electrode connection position 2 of the silicon semiconductor substrate 1. , when a semiconductor device having the electrodes described above in FIG. There is no desire to see a phenomenon in which silicon in the region below the electrode connection position 2 of 1 diffuses into the platinum/silicide layer 10 whose matrix is polycrystalline silicon.
Furthermore, even if there is a platinum-aluminum intermetallic compound layer connected to the platinum-silicide layer 10 having polycrystalline silicon as the host, the platinum-silicide layer 10 having polycrystalline silicon as the host Due to the heat treatment for other purposes on the silicon semiconductor substrate 1, the platinum/aluminum intermetallic compound of the platinum/aluminum intermetallic compound layer 11 is transferred to the electrode connection position 2 of the silicon semiconductor substrate 1.
During actual use of a semiconductor device that does not have a phenomenon of penetrating into the underlying region and has the electrodes described above in FIG. It does not have the problem of diffusion of silicon in the area under the electrode connection position 2 of the silicon semiconductor substrate 1 or the area under the electrode connection position 2 of the silicon semiconductor substrate 1 into the platinum-aluminum intermetallic compound layer 11. 1, the semiconductor device having the electrodes shown above in FIG. I don't have the fear of getting what I don't have, and
The characteristics of the semiconductor device having the electrodes shown in the drawings are not likely to change beyond the predetermined values due to long-term use.

Therefore, the semiconductor device having the electrodes described above in FIG. 1 can effectively avoid the drawbacks mentioned at the beginning.

This means that ten semiconductor devices having the above-mentioned electrodes shown in FIG. (However, in this case, the thickness of the platinum-aluminum intermetallic compound layer 11 was approximately 350 OA).
, all 10 of the semiconductor devices having the above-mentioned electrodes in FIG. 1 are shown by lines connecting the circles in FIG.
Even after a temperature step of 00°C, the PN junction 5
Results were obtained in which the reverse voltage of For 10 pieces of the semiconductor device, as shown in FIG. 1, except that 3 is replaced with an aluminum layer,
When a similar temperature step stress test was conducted, as shown by the line connecting the x marks in Figure 2, all 10 of the semiconductor devices in this case underwent a temperature step of 375°C. This is clear from the results obtained assuming that the withstand voltage of the PN junction is zero.

Further, in the case of a semiconductor device having an electrode according to the present invention as described above in FIG. Since it is disposed on the platinum-aluminum intermetallic compound layer 11 disposed on the aluminum layer 10 and exposed to the outside, it is possible to punch the wiring conductor into the aluminum layer 12, and the punching is performed at the beginning. As mentioned above, it is easy.

Therefore, bonding of a wiring conductor to the electrode 3 in a semiconductor device having the electrode described above in FIG. 1 is as easy as in the case where the electrode is made of only an aluminum layer.

Also, even if the aluminum layer 12 extends over the insulating layer 9 as shown, the aluminum layer 12 is obtained with good adhesion to the insulating layer 9, as described at the outset.

Furthermore, in order to obtain an aluminum layer 12 with a desired pattern that can be extended onto the insulating layer 9, this is formed on the silicon semiconductor substrate 1.
Even if it is obtained by selective etching of the aluminum layer deposited thereon, the selective etching is easy, as mentioned at the outset.

Therefore, in the case of a semiconductor device having an electrode according to the present invention as described above in FIG. It is something that you have.

The above description describes an embodiment in which the present invention is applied to a semiconductor device having an electrode that can function as a semiconductor diode. It will be obvious that the present invention can be applied to semiconductor devices having various types of electrodes, including electrodes arranged in ohmic connection.

[Brief explanation of the drawing]

FIG. 1 is a linear cross-sectional view showing an embodiment of a semiconductor device having electrodes according to the present invention, and FIG. 2 is a curve diagram showing the results of a temperature step stress test thereof and similar results of a semiconductor device having conventional electrodes. It is. In the figure, 1 is a silicon semiconductor substrate, 2 is an electrode connection position, 3 is an electrode, 4 is a semiconductor layer, 5 is a PN junction, 6 is a main surface, 7 is a semiconductor region, 8 is a window, 9 is an insulating layer, and 10 is a multilayer Reference numeral 11 indicates a platinum/silicide layer based on crystalline silicon, a platinum/aluminum intermetallic compound layer, and 12 an aluminum layer.

Claims (1)

[Claims] 1. In a semiconductor device having an electrode arranged at a required position on a silicon semiconductor substrate in ohmic connection with the silicon semiconductor substrate, the electrode is arranged in a polycrystalline manner at the required position in ohmic connection with the semiconductor device. A platinum/silicide layer having silicon as a matrix, a platinum/aluminum intermetallic compound layer disposed on the platinum/silicide layer in connection with the platinum/aluminum intermetallic compound layer, and a platinum/aluminum intermetallic compound layer disposed on the platinum/aluminum intermetallic compound layer. 1. A semiconductor device having an electrode comprising an aluminum layer disposed in connection with an aluminum layer.