JPH03261178A - Semiconductor device and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent charge storage in a channel region and to prevent a kink effect by discharging charge generated at the channel region as a current to a source region by a high melting point metal film formed on an insulating film under the channel region and the source region. CONSTITUTION:A high melting point metal film 12 is formed on an insulating film 2 under a channel region 6 and a source region 5 of a MOS transistor. When biases are respectively applied to drain, source electrodes 4, 5 and the electrode of a gate 8 to operate the transistor, charge is generated at the region 6 due to an impact ionization, etc., and discharged to the region 5 through the film 12. Thus, charge storage at the region 6 can be prevented, and deterioration of the characteristics of the transistor due to a kink effect can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device and a method for manufacturing the same, and particularly relates to an SOI device created by forming an insulating film and a semiconductor layer on a semiconductor substrate and a method for manufacturing the same. be.

[Prior art] Figures 2 (a), (b), and (C) show a conventional S of this type.
1 shows a cross-sectional view of the formation process of an ol device. In the figure,
1 is a semiconductor substrate, 2 is an insulating oxide film, 3 is a semiconductor layer, 4 is a drain region, 5 is a source region, 6 is a channel region, 7
is a gate oxide film, 8 is a gate, 9 is a wiring isolation oxide film, 1
0 is a drain electrode, and 11 is a source electrode.

First, as shown in FIG. 2(a), an absolute oxide film 2 and a semiconductor layer 3 are formed on a semiconductor substrate 1. Next, as shown in FIG. After removing the part leaving behind gate oxidation 1f17, gate 8
, and further, drain and source regions 4.5 are formed. Next, as shown in FIG. 2(C), wiring isolation oxidation M9
After forming, drain.

A portion of the source region 4.5 is removed to form a drain and source electrode 10.11.

[Problem to be solved by the invention] In the conventional device, the bottom of the tank is placed as described above, so when a bias is applied to each electrode and the device is operated, impact ionization occurs in the channel region 6 which is in a floating state. Charges are accumulated due to such factors, and the characteristics of the MOS transistor deteriorate due to the influence thereof, and this kink effect adversely affects the operation of the transistor.

The present invention has been made to solve the above-mentioned problems, and provides a semiconductor device and a method for manufacturing the same that can prevent charge accumulation in the channel region 6 and obtain a MOS transistor with normal characteristics. The purpose is to obtain.

[Means for Solving the Problems] A semiconductor device and a method for manufacturing the same according to the present invention include a MOS
) A refractory metal film is formed on the insulating oxide film below the channel region and source region of the transistor.

[Effect]

In the present invention, accumulation of charges can be prevented by causing charges generated in the channel region to flow as a current to the source region through the high melting point metal film.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of the process of forming a semiconductor device according to an embodiment of the present invention. In the figure, 1 is a semiconductor substrate, 2 is an insulating oxide film, 3 is a semiconductor layer, 4 is a drain region, 5 is a source region, 6 is a channel region, 7 is a gate oxide film, 8 is a gate, and 9 is a wiring isolation oxide film , 10 is a drain electrode, 11
1 is a source electrode and 12 is a high melting point metal film.

First, as shown in FIG. 1(a), an insulating oxide film 2 and a high melting point metal film 12 are formed on a semiconductor substrate 1, leaving only the parts that span the channel and source regions of an MO5 transistor. The high melting point metal film 12 is removed.

Next, as shown in FIG. 1Cb), a semiconductor layer 3 is formed on the insulating oxide film 2 and the high melting point metal M12. Next, Figure 1 (C
), a portion of the semiconductor layer 3 excluding the MOS transistor region is removed, and a gate oxide film 7. After forming the gate 8, drain and source regions 4.5 are formed. Furthermore, as shown in FIG. 1(d), a wiring isolation oxide film 9 is formed to form a drain.

A part of the source region is removed, and the drain and source electrodes 10 are removed.
．． 11 is formed.

When a MOS transistor is operated by applying a bias to each of the drain and source electrodes 4 and 5 and the gate 8 electrode (not shown), charges are generated in the channel region by impact ionization, etc., but the refractory metal film 12 By discharging charges to the source region 5 through the channel region 6, charge accumulation in the channel region 6 can be prevented, and deterioration of characteristics of the transistor due to the kink effect can be prevented.

In the above embodiment, an example was described in which an oxide film was used as the insulating film and the gate insulating film, but any film may be used as long as it can be electrically insulated. Further, the high melting point metal film 12 may be made of any material, such as tungsten, as long as it can withstand heat treatment during formation of a MOS transistor.

[Effects of the Invention] As described above, according to the semiconductor device and the manufacturing method thereof according to the present invention, the charges generated in the channel region can be reduced by the high melting point metal film formed on the insulating film below the channel region and the source region. By discharging current to the source region, charge accumulation in the channel region is prevented, the kink effect is suppressed, and normal transistor characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the process of forming a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the process of forming a conventional device. In the figure, l is a semiconductor substrate, 2 is an insulating oxide film, 3 is a semiconductor layer, 4 is a drain region, 5 is a source region, 6 is a channel region, 7 is a gate oxide film, 8 is a gate, and 9 is a wiring isolation oxide film , 10 is a drain electrode, 11 is a source electrode, 1
2 indicates a high melting point metal film. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) In a SOIMOS transistor in which an insulating film and a semiconductor layer are formed on a semiconductor substrate, and a MOS transistor is formed in the semiconductor layer, a MOS transistor is formed on the channel region under the gate electrode and the insulating film under the source region of the SOIMOS transistor. What is claimed is: 1. A semiconductor device comprising: a high-melting-point metal film, which causes charges generated and accumulated in a channel region to flow as a current to a source region, thereby preventing charge accumulation in the channel region. (2) a step of forming an insulating film on the semiconductor substrate; a step of forming a high melting point metal film over the portions of the insulating film that are to become the channel and source regions of the MOS transistor; and the insulating film and a step of forming a semiconductor layer on a portion of the high melting point metal film that is to become a MOS type transistor; a step of forming a gate electrode on the semiconductor layer so as to cover a part of the high melting point metal film; 1. A method of manufacturing a semiconductor device, comprising the step of forming drain and source regions in a layer.