JPS5848459A - Semiconductor device - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of semiconductor device preventing the metal electrode from penetrating into the semiconductor even under high temperature by a method wherein the nitride layer of transition metal such as Ti, etc. is held between the semiconductor substrate and the excellent conductive metal layer to attain the purpose. CONSTITUTION:The Ti nitride layer 9 is formed by reactive sputtering of approximate 100-1,000Angstrom in the low pressure mixed gas of N2 and Ar with the mixing ratio of say 1:5. Then Pt layer 10 is formed on said layer 9 by sputtering or evaporation while Au layer 11 is likewise formed by evaporation etc. When the electrode is constituted by means of arranging the Ti nitride layer 9 between the semiconductor and the excellent conductor such as Pt 10, Au 11 etc., the barrier effect against the diffusion of the Pt layer 10 into the emitter region 7 and the base region 6 may be further improved by said Ti nitride layer 9 with fine composition facilitating the manufacture of bipolar transistor with excellent heat resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to an electrode structure of a semiconductor device.

Highly reliable 6 degree semiconductor devices, especially bipolar transistors,
Electrodes such as diodes are required to have heat resistance, migration resistance, destruction resistance, corrosion resistance, etc.

For this reason, Ti-Pt-A as shown schematically in Fig.
U-structured electrodes are used. It is assumed that the silicon 1 on which the electronic circuit element is formed has already had a metal such as platinum silicide formed thereon to obtain ohmic contact. Here, 2 Ti layers are formed on other parts of the silicon 1, and 8i0. The Pt layer 3 is for adhesion with the protective film on the surface of the layer 5 and for the barrier and wall effect against the penetration of Pt3 into the silicon 1).
The Au layer 4 serves as a current conductor and as a protective film.

However, even when using an electrode with the Ti-Pt-Au structure as shown in Figure 1, it is difficult to avoid the penetration of the electrode constituent metal into the silane layer at high temperatures, making it difficult to obtain sufficient heat resistance. there were. In addition, in the case of the electrode in Fig. 1, Tl-P
An alloy layer is formed at the t-interface, and this alloy layer may be difficult to etch during electrode formation.

An object of the present invention is to provide a semiconductor device that does not allow electrode constituent metal to penetrate into the semiconductor even at high temperatures and is easy to manufacture.

The semiconductor device according to the present invention has a transition metal nitride layer such as a Ti layer between a semiconductor substrate and a highly conductive metal layer as its electrode structure. Thus, a semiconductor device is obtained in which the metal constituting the upper highly conductive metal layer is prevented from entering the underlying semiconductor layer.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

Referring to FIGS. 2a and 2b, which are cross-sectional views of a bipolar transistor as an embodiment of the present invention, first, FIG.
As shown in FIG. 2, a space region 6 and an emitter region 7 are formed in a collector region 5 which is a semiconductor substrate or an epitaxial layer. A Pt silicide layer 8 is formed by depositing a surface layer such as a silicon oxide layer 11J [12K] with an opening for removing the electrode and alloying it with each region by heat treatment. Unreacted PT on the surface protective film 12 and the like is removed. Then, use a low-pressure mixed gas of N and Ar, for example, at a mixing ratio of 1:5.
A Ti nitride layer 9 is formed by reactive sputtering of about 100 to 1000 Ti. By sputtering or evaporating a %ptpt layer thereon,
The Au layer 11 is similarly formed by vapor deposition or the like. Next, as shown in Figure 2, using a mask such as 7-otoresist (not shown), selectively remove it by ion milling or the like.
An extraction electrode having a nitride 9-Pt1O-Aull structure is formed.

As shown in Figure 2, by forming an electrode structure in which the Tl nitride 9 is placed between the semiconductor and a good conductor such as Pt10 or Au11, the Ti nitride layer 9 with a dense composition can The barrier effect of the PT layer 10 against diffusion into the back region 7 and the space region 6 is even greater, and a bipolar transistor with excellent heat resistance can be obtained. Therefore, it is possible to obtain an ultra-high reliability element that exhibits little variation in the electrical characteristics of a transistor or the like under high temperatures and has a sufficient lifespan. □ Furthermore, the TI nitride layer 9 is stable and does not react with the Pt layer 1O, and can be easily processed even when using a wafer, a toe, or a etch for electrode processing.

In ζζ, we explained bipolar transistors, but
It goes without saying that the present invention is similarly applicable to diodes, field effect transistors, and monolithic integrated circuits containing these elements. In addition, W and Mo were added to the Ti nitride 9.

Similar effects can be expected by using nitrides of transition metals such as Cr.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an electrode of a conventional structure, and FIGS. 2a and 2 are cross-sectional views showing an embodiment of the present invention in the order of manufacturing steps.

Claims (3)

[Claims] (1) a semiconductor region, a first metal layer in resistive contact with the semiconductor region, a second metal layer made of a transition metal nitride in contact with the first metal layer, and a second metal layer; and a highly conductive third metal layer formed on the layer. (2) The second metal layer is titanium or tungsten. The semiconductor device according to claim 1, which is a nitride of a metal selected from molybdenum and chromium. (3) The first metal layer is made of platinum silicide, the second metal layer is made of titanium nitride, and the third metal layer is made of platinum in contact with the second metal layer. 2. The semiconductor device according to claim 1, wherein the semiconductor device has a multilayer structure with gold in contact with the semiconductor device.