JPH01248567A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To suppress an increase in a gate resistance without varying the thickness of an oxide film formed on the sidewall of a gate electrode eve if a gate metal is thinned by forming a silicon oxide film or a silicon nitride film and a silicide film on the upper layer of the gate electrode of a multilayer made of a gate metal and its silicide. CONSTITUTION:Silicon is ion implanted to the main surface of a semi-insulating GaAs substrate 1 to form an N-type buried layer 2. Then, a gate tungsten silicide film 3, a gate tungsten 4, a silicon oxide film 5, a tungsten silicide film 6 are sequentially deposited. Thereafter, a deposited layer is removed by dry etching except in a region for forming an electrode. Then, a silicon oxide film 7a is deposited on the whole substrate. Subsequently, a sidewall 7b is formed by dry etching, with the sidewall as a mask silicon is ion implanted to form an N-type diffused layer 8. Then, an N<+> type epitaxial layer 9 is formed by epitaxial growth. Then, the films 7b, 5 and the film 6 are removed to form a semiconductor device.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for manufacturing a semiconductor device.

[Existing technology] Junction FETs, whose gate is a short-socket contact consisting of contact between a metal and a semiconductor, have a simple structure and manufacturing process. Elements with excellent high frequency characteristics using GaAs with high mobility,
Integrated circuits with high speed operation have been obtained.

FIGS. 3(a) to 3(g) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining an example of a conventional method for manufacturing a semiconductor device. As shown in Figure 3(a), semi-insulating Ga
An N-type buried layer 2 is formed on the main surface of an As substrate 1. next,
As shown in FIG. 3(b), a tungsten silicide film 23 for a gate is formed over the entire surface of the substrate. Next, Figure 3 (c
), a gate electrode is formed by photolithography. Next, as shown in FIG. 3(d), a sidewall silicon oxide film 7a is deposited over the entire surface of the substrate. Next, Figure 3 (e
), the silicon oxide film other than the side wall portions of the gate electrode is removed by anisotropic dry etching. Next, as shown in FIG. 3(f), in order to reduce the resistance between the saw and the drain, using the silicon oxide film 7b and the gate electrode 23 as a mask, N-type impurities are ion-implanted by a self-alignment method. N+ type dispersed layer 10 is formed, then,
As shown in FIG. 3(g), a semiconductor device was formed by removing the silicon oxide film 7b.

[Problem to be solved by the invention]

In the conventional semiconductor device manufacturing method described above, a second layer is formed in the upper layer.
In the case of multi-layer wiring, in order to facilitate flattening of the lower layer, the gate metal must be made thinner, and the thickness of the oxide film formed on the side walls of the gate electrode also becomes thinner, causing ions to pass through during ion implantation. It gets injected. Furthermore, the thin layer of the gate increases the gate resistance.

The purpose of the present invention is to prevent the thickness of the oxide film formed on the side walls of the gate electrode from changing even when the gate metal is thinned due to planarization for multilayer wiring, and to suppress an increase in gate resistance. An object of the present invention is to provide a method for manufacturing a semiconductor device.

[Means for Solving the Problems]-1 The method for manufacturing a semiconductor device of the present invention includes the step of selectively forming a buried layer of one conductivity type on one main surface of a semiconductor substrate, and forming a first silicide film on the mold burying layer; forming a metal film on the first silicide film; and forming a first silicon oxide film or silicon nitride film on the metal film. a step of forming a second silicide film on the first silicon oxide film or silicon nitride film; and a step of forming a second silicide film on the first silicon oxide film or silicon nitride film; a step of selectively removing the upper portion; a step of forming a second silicon oxide film on the entire surface of the substrate; and a step of selectively etching the second silicon oxide film other than the side wall portion of the portion that will become the gate electrode. a step of ion-implanting impurities of one conductivity type using the gate portion and the second silicon oxide film as masks to form a layer of one conductivity type; and a step of forming a layer of one conductivity type by using the gate portion and the second silicon oxide film as masks; , removing the second silicide film and the second silicon oxide film.

〔Example〕

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

FIGS. 1(a) to 1(kl) are cross-sectional views of a semiconductor chip shown in order of steps for explaining a first embodiment of the present invention. As shown in FIG. 1(a), a semi-insulating GaAs substrate 1
An N-type buried layer 2 is formed by ion-implanting silicon onto the main surface of the substrate at an acceleration energy of 50 keV and a dose of 2×10 12 cm −2 . Next, as shown in FIG. 1(b), for example, a tungsten silicide film 3, which is a silicide, is deposited to a thickness of 0.2 μm, and a tungsten 4 for the gate is deposited to a thickness of 0.1 μm. Next, Figure 1 (C
), the silicon oxide film 5 is further coated with a thickness of 0.2 μm.
A tungsten silicide film 6 is deposited to a thickness of 0.1 μm. Next, as shown in FIG. 1(d), the deposited layer other than the area where the electrodes will be formed is removed by dry etching. Next, as shown in FIG. 1(e), a silicon oxide film 7a is deposited to a thickness of 0.2 μm over the entire surface of the substrate. Next, as shown in FIG. 1(f), 1. A side wall portion 7b is formed by dry etching, and using the side wall portion as a mask, silicon is accelerated at an energy of 50 keV and a dose of 6×.

An N-type diffusion layer 8 is formed by ion implantation at IO"cm-2. Next, as shown in FIG. 1(g),
Similarly to FIG. 3(f), an N++ epitaxial layer 9 is formed by epitaxial growth in order to reduce the resistance between the source and drain.

Next, as shown in FIG. 1(h), the silicon oxide film 7b
, 5 and the tungsten silicide film 6, a semiconductor device is formed.

FIGS. 2(a) to 2(c) are cross-sectional views of a semiconductor chip knob shown in the order of steps for explaining a second embodiment of the present invention. As shown in FIG. 2(a), a silicon oxide film 7a with a thickness of 0.2. A thickness of +1 m is deposited, and then the side wall portion 7b is formed by dry etching. Next, Figure 2(b)
As shown in Figure 2, in order to reduce the resistance between the source and the drain, silicon was accelerated at an energy of 120 keV and at a dose of 6 x 10 Cffl-2 using the side wall as a mask.
By performing ion implantation, an N+ type scattering layer 10 is formed. Next, as shown in FIG. 2(c), the silicon oxide films 7b and 5 and the tungsten silicide film 6 are removed to form a semiconductor device. In the second embodiment, the N++ epitaxial layer 9 in the first embodiment is not formed, but the silicon ion implantation concentration is increased to form an N+
Although a type scattering layer 10 is formed, the effects of this embodiment are similar to those of the first embodiment.

In the two embodiments described above, tungsten was used for the gate metal and its silicide, but for example, Ti, Pt
, Nb, Ta, Mo, and their silicides, similar effects can be obtained.

Further, in this embodiment, a silicon oxide film is used as the material formed on the metal film, but similar effects can be obtained by forming a semiconductor device using silicon nitride in other embodiments.

〔Effect of the invention〕

As explained above, in the present invention, a silicon oxide film or a silicon nitride film, and a silicide film are further formed on the upper layer of a multilayer gate electrode made of five gate metals and their silicides, which is used as a mask during ion implantation. Since the silicon oxide film on the side wall of the electrode does not have to be thin, it is effective to prevent ions from being through-implanted during ion implantation. Silicon oxide film or silicon nitride (
Since the metal film and silicide film can be removed and the thickness of the electrode can be made thinner, it is easier to planarize the lower layer for multilayer wiring.Moreover, since the gate electrode is a multilayer gate of metal and silicide, the gate electrode can be made thinner. This has the effect of preventing an increase in gate resistance due to thinning of the layer.

[Brief explanation of the drawing]

FIGS. 1(a) to (h) are cross-sectional views of a semiconductor chip shown in the order of steps for explaining the first embodiment of the present invention, and FIGS. FIG. 3(a) is a cross-sectional view of a semiconductor chip shown in the order of steps for explaining an embodiment of the present invention.
-(g) are cross-sectional views of a semiconductor chip shown in order of steps for explaining an example of a conventional method for manufacturing a semiconductor device. DESCRIPTION OF SYMBOLS 1... Semi-insulating GaAs substrate, 2... N-type buried layer, 3... Tungsten silicide film for gate,
4... Tungsten film for gate, 5... Silicon oxide film, 6... Tungsten silicide, 7a, 7b
...Silicon oxide film, 8...N-type diffusion layer, 9...
N++ epitaxial layer, 10...N+ type scattering layer 2
3...Tungsten silicide layer for gate.

Claims (2)

[Claims] (1) selectively forming a buried layer of one conductivity type on one main surface of a semiconductor substrate; forming a first silicide film on the semiconductor substrate and the buried layer of one conductivity type; forming a metal film on the first silicide film; forming a first silicon oxide film on the metal film; and forming a second silicide film on the first silicon oxide film. a step of selectively removing a portion of the semiconductor substrate and the buried layer of one conductivity type other than a region where a gate electrode is to be formed; and a step of forming a second silicon oxide film on the entire surface of the substrate. ,
selectively removing the second silicon oxide film other than the sidewall portion of the portion that will become the gate electrode by etching;
forming a layer of one conductivity type by ion-implanting impurities of one conductivity type using the gate portion and the second silicon oxide film as masks; 1. A method for manufacturing a semiconductor device, comprising the step of removing a silicon oxide film. (2) selectively forming a buried layer of one conductivity type on one main surface of the semiconductor substrate; and forming a first silicide film on the semiconductor substrate and the buried layer of one conductivity type; forming a metal film on the first silicide film; forming a silicon nitride film on the metal film; forming a second silicide film on the silicon nitride film; A step of selectively removing a portion of the semiconductor substrate and the buried layer of one conductivity type other than the region where an electrode is to be formed, a step of forming a silicon oxide film on the entire surface of the substrate, and a step of etching the portion that will become the gate electrode. a step of selectively removing the silicon oxide film other than the side wall portion; a step of ion-implanting impurities of one conductivity type using the gate portion and the silicon oxide film as a mask to form a layer of one conductivity type; and a step of forming a layer of one conductivity type. , a step of removing the second silicide film and the silicon oxide film.