GB2104290A

GB2104290A - Semiconductor device and method for manufacturing the same

Info

Publication number: GB2104290A
Application number: GB08223534A
Authority: GB
Inventors: Yoshio Yokota; Shunichi Hiraki
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1981-08-18
Filing date: 1982-08-16
Publication date: 1983-03-02
Also published as: GB2104290B; DE3230568A1; JPS5830147A

Abstract

The invention provides a semiconductor device which has an electrode or wiring layer (4) which contacts a silicon substrate (2) and which is made of a nitride or carbide of a transition element which is a member selected from the group consisting of titanium, hafnium, zirconium, tantalum, niobium, scandium and molybdenum. In a method for manufacturing the semiconductor device the layer (4) is deposited by high frequency sputtering and a layer (5) of Ni is deposited on the layer (4). Grooves in the device receive a glass film (8) and electrodes (9) contact the Ni layer (5). <IMAGE>

Description

SPECIFICATION Semiconductor device and method for manufacturing the same The present invention relates to a semiconductor device and a method for manufacturing the same and, more particularly, to a semiconductor device with an improved electrode or wiring layer material and a method for manufacturing the same.

Aluminum (at), Nickel (Ni), Vandium (V), Plantinum silicide (PtSi2), Titanium (Ti) or polycrystalline silicon have been used as the electrode or wiring layer material of semiconductor devices. However, the above materials except for polycrystalline silicon are readily oxidized and have low resistance to chemicals. Further, even at relatively low temperatures of 300 to 500 C, the materials react with silicon of a substrate to form silicides. As a result, the wiring resistance is increased, and the silicide peels off at the interface with silicon due to differences in volume expansion coefficients of the silicide and silicon or thermal expansion coefficients thereof.

Further, the contact resistance thereof is also increased. After one of the materials described above is deposited as the electrode or wiring layer material on the silicon substrate, annealing can hardly be performed at a temperature above 50000.

It is, therefore, an object of the present invention to provide a highly reliable semiconductor device with an electrode or wiring layer which does not produce an undesirable silicide, and a method for manufacturing the same.

According to one aspect of the present invention, there is provided a semiconductor device having a silicon substrate and a conductive layer which is formed directly on-said silicon substrate and which comprises a nitride or carbide of a transition element, wherein said transition element is a member selected from the group consisting of titanium, hafnium, zirconium, tantalum, niobium, scandium and molybdenum.

According to another aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising the steps of: forming a conductive layer of a nitride or carbide of a transition element on a silicon substrate, said transition element being a member selected from the group consisting of titanium, hafnium, zirconium, tantalum, niobium, scandium and molybdenum; forming a groove by selectively etching said conductive layer and said silicon substrate; covering a surface of said groove with a glass layer; and sintering said glass layer by annealing.

In the present invention, the conductive layer comprises at least one of the electrodes and the wiring layers.

This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Figures 1 to 6 are sectional views for explaining the step of manufacturing a semiconductor device according to one embodiment of the present invention.

A method for manufacturing a semiconductor device according to one embodiment of the present invention will be described with reference to Figures 1 to 6. Referring to Figure 1, an n±type conductive layer 2 is formed in one major surface of an n-type silicon substrate 1 by the conventional diffusion method to a depth of 30 #m.A P±type conductive layer 3 is formed in the other major surface of the n-type silicon substrate 1 by the conventional diffusion method to a depth of 100 Fm. Titanium nitride (TiN) films 4 including 10 to 80 atomic % of nitrogen, nickel (Ni) films 5 and silicon nitride (S3N4) films 6 are sequentially deposited by high frequency sputtering on the n±type conductive layer 2 and the p±type conductive layer 3 respectively to thicknesses of 3,000 A, 4,000 A, and 1,000 A, using titanium (Ti) as a target and introducing a gas mixture of argon and nitrogen in a vacuum of about 10-3 Torr.

Wax coatings 7 which have an oxidation resistance are formed on the silicon nitride films 6. As shown in Figure 3, the titanium nitride films 4, the nickel films 5 and the silicon nitride films 6 are selectively etched by photoetching to form openings. Subsequently, as shown in Figure 4, a wax coating 7' is formed only on the the wax coating 7 above the major surface of the silicon substrate 1.

The surface layers of the openings are etched by an etchant mixture of hydrogen fluoride (HF) and nitric acid (HNO3) to form grooves which reach the p±type conductive layer 3. The depth of the grooves is about 60 ,um, and mesa portions MS are formed.

As shown in Figure 5, the wax coatings 7 and 7' are removed, and low-melting point glass films 8 of zinc oxide (ZnO) are formed at the edges of the mesa portions MS, that is, on the walls of the grooves and are sintered in an oxygen atmosphere at a temperature of 700 to 80000. In this condition, if the titanium nitride film 4 reacts with silicon to form a silicide to the surface of the nickel film 5, the electrode cannot be soldered in a later step. However, in this embodiment, since the titanium nitride film 4 which comprises a transition element nitride is used, silicide reaction may not extend to the nickel film 5.

As shown in Figure 6, the silicon nitride films 6 are etched by plasma etching to expose the surfaces of the nickel films 5. Electrodes 9 for connection of external leads are then deposited only on the surfaces of the exposed portions of the nickel films 5.

According to the semiconductor device with the above arrangement, since the transition element nitride films are formed to prevent silicide formation, the wiring resistance may not be increased. Further, the silicide may not peel off at the interface with silicon due to the difference in the volume expansion coefficients of the silicide and silicon and thermal expansion coefficients thereof, and the contact resistance may not be increased. According to the method for manufacturing the semiconductor device according to the present invention, the photoengraving process for forming wiring electrodes can be omitted. As a result, the manufacturing process is simplified.

In the above embodiment, the transition element nitride is used. However, a transition element carbide which includes 10 to 80 atomic % of carbon may also be used. Most preferably, the ratio of N or C: transition element should be 50 : 50. In the above embodiment, Ti is used as the transition element.

However, Hf, Zr, Ta, Nb, Sc or Mo may also be used.

Hf or Zr whose nitride exhibits resistance as low as that of TiN can be used like Ti. Resistance of the nitride of Ta, Nb, Sc or Mo is slightly higher than that of TiN, but is negligibly low in practice.

Further, in the above embodiment, the transition element nitride or carbide which includes 10 to 80 atomic % of nitrogen or carbon is used. However, the above material can also be used as the wiring layer material. A cobalt (Co) film may be used in place of the nickel film 5 of the above embodiment.

Claims

1. A semiconductor device having a silicon substrate and a conductive layer which is formed directly on said silicon substrate and which comprises a nitride or carbide of a transition element, wherein said transition element is a member selected from the group consisting of titanium, hafnium, zirconium, tantalum, niobium, scandium and molybdenum.

2. A semiconductor device according to claim 1, wherein said nitride of said transition element includes 10 to 80 atomic % of nitrogen.

3. A semiconductor device according to claim 1, wherein said carbide of said transition element includes 10 to 80 atomic % of carbon.

4. A semiconductor device according to claim 1, wherein said conductive layer comprises at least one of electrode and wiring layers.

5. A semiconductor device according to claim 1, wherein a soldered layer connected to an external lead is formed on said conductive layer through at least one of nickel and cobalt layers.

6. A method for manufacturing a semiconductor device, comprising the steps of: forming a conductive layer of a nitride or carbide of a transition element on a silicon substrate, said transition element being a member selected from the group consisting of titanium, hafnium, zirconium, tantalum, niobium, scandium and molybdenum; forming a groove by selectively etching said conductive layer and said silicon substrate; covering a surface of said groove with a glass layer; and sintering said glass layer by annealing.

7. A method for manufacturing a semiconductor device, comprising the steps of: forming a conductive layer made of a nitride or carbide of a transition element, at least one of nickel and cobalt layers, and a passivation film sequentially on a silicon substrate, said transition element being a member selected from the group consisting of titanium, hafnium, zirconium, tantalum, niobium, scandium and molybdenum; forming a groove by selectively etching said conductive layer, said at least one nickel and cobalt layers, said passivation film and said silicon substrate; covering a surface of said groove with a glass layer; sintering said glass layer by annealing; and etching said passivation film to expose said at least one nickel and cobalt layers and forming a soldered layer which is connected to an external lead on an exposed portion of said at least one of nickel and cobalt layers.

8. A method for manufacturing a semiconductor device according to claim 6 or 7, wherein said nitride of said transition element includes 10 to 80 atomic % of nitrogen.

9. A method for manufacturing a semiconductor device according to claim 6 or 7, wherein said carbide of said transition element includes 10 to 80 atomic % of carbon.

10. A method for manufacturing a semiconductor device according to claim 6 or 7, wherein said conductive layer comprises at least one of electrode and wiring layers.

11. A semiconductor device according to claim 1, wherein said conductive layer is made of titanium nitride and 3,000 A thick.

12. A semiconductor device and method for manufacturing the same, substantially as hereinbefore described with reference to the accompanying drawings.