JPH063809B2 - Semiconductor device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device including an insulated gate field effect transistor that operates stably in a radiation environment.

[Conventional technology]

Currently, a semiconductor device using silicon or the like as a semiconductor substrate is an insulated gate field effect transistor (hereinafter referred to as MIS).
There are a great many types including "FET").

In such a semiconductor device, not only the MIS FET but also the field region or the like for insulating the element regions from each other may have the MIS structure.

Conventionally, a silicon oxide film (hereinafter simply referred to as a SiO ₂ film) obtained by thermally oxidizing the surface of a semiconductor substrate has been widely used as an insulator of a MIS structure when the material of the semiconductor substrate is silicon. There is.

This is because this method can relatively easily obtain a good-quality insulating film having a clean interface and has good electrical characteristics.

[Problems to be solved by the invention]

2. Description of the Related Art In recent years, with the practical use of various artificial satellites, there is a demand for semiconductor devices that operate stably even in a radiation environment.

However, since the conventional semiconductor device described above is composed of a MIS FET using a thermally oxidized SiO ₂ film as an insulator, its characteristics deteriorate as the absorbed dose increases when operated in a radiation environment. There are drawbacks.

The reason for this is that from the various research conducted so far,
It is known that it is caused by a change in the electrical characteristics of the SiO ₂ / Si structure portion, and it is mainly caused by (1) formation of positive charges in the SiO ₂ film and (2) formation of SiO ₂ / Si interface states. It is supposed to be.

The object of the present invention is to obtain SiO ₂ / S in a radiation environment.
An object of the present invention is to provide a semiconductor device having a high degree of integration that can suppress deterioration of device characteristics due to a change in electrical characteristics of an i-structure portion.

[Means for solving problems]

A feature of the present invention is a semiconductor device having a field effect transistor formed on a semiconductor substrate, wherein the gate insulating film of the field effect transistor is composed only of an oxide film grown using tetraethylorthosilicic acid. .

〔Example〕

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

FIG. 1 is a sectional view of an embodiment of the present invention.

In this embodiment, a gate 4 of a polycrystalline silicon film is arranged on a P-type silicon substrate 1 through an oxide film (hereinafter referred to as TEOS film) 3 grown using tetraethylorthosilicic acid, and n ⁺ diffusion is performed. 1 shows a semiconductor device including a MIS FET composed of a source 5 and a drain 6 of a layer.

FIG. 2 is a sectional view of a technique related to the present invention.

In FIG. 2, SiO is formed on the P-type silicon substrate 1 '.
_Two insulating films 3 ″ and a TEOS film 3 ′ are provided, and a gate 4 ′ and a ground electrode 4 ″ of a phosphorus-doped polycrystalline silicon film are provided through the insulating film 3 ″ and the TEOS film 3 ′, and further n ⁺ Sources 5 ', 5 "and a drain 6'of the diffusion layer are provided on the surface of the silicon substrate 1'. Here, insulating film 3 "
The TEOS film 3'and the TEOS film 3'are gate insulating films of a MIS FET composed of a source 5 ', a drain 6', and a gate 4 ', and the surface of the silicon substrate 1'underneath serves as a channel region. On the other hand, the ground electrode 7'consists of the surface potential by forming an MIS with the underlying insulating film 3a "and TEOS film 3a 'and the silicon substrate 1'.
The element isolation region is formed so that no parasitic channel region is formed on the surface of the device.

Since the TEOS film has more recombination centers contained in the film than the thermally oxidized SiO ₂ film, recombination of electrons and holes generated by the incident ionizing radiation is promoted, and It is possible to greatly reduce the amount of positive charges trapped in the trap. Further, the TEOS film has a better control of the growth film thickness of the thin film than the oxide film deposited by the vapor phase chemical growth method using the conventional silane-based gas, so that the gate insulation of the MIS FET can be achieved without the thermal oxidation. A film can be formed.

3 (a) to 3 (f) are cross-sectional views of a semiconductor chip showing the order of steps for explaining the method for manufacturing a semiconductor device according to the embodiment of the present invention.

First, as shown in FIG. 3A, the P-type silicon substrate 1 is thermally oxidized to form Si on the surface of the silicon substrate 1.
An insulating film 2a of an O ₂ film is formed, and a nitride film is further formed as an insulating film 2b.

Next, as shown in FIG. 3 (b), a photoresist film 10 covering a portion to be an element region is formed in a predetermined pattern, and the insulating film 2b is masked by the ordinary reactive ion etching method using the photoresist film 10 as a mask. And 2a, the nitride film and the SiO ₂ film are etched.

Next, as shown in FIG. 3C, the photoresist film 10
Then, the silicon substrate 1 is thermally oxidized using the remaining insulating film 2b as an anti-oxidation mask to form a SiO ₂ film which will become the insulating film 2 for element isolation.

Then, after removing the nitride film and the SiO ₂ film of the insulating films 2b and 2a, as shown in FIG. 3 (d), a TEOS film 3 is deposited on the surface of the substrate by the CVD method, and further phosphorus-doped polycrystalline After growing the silicon film 4a, the photoresist film 11 is formed in a predetermined pattern.

Next, as shown in FIG. 3 (e), the photoresist film 11
Using the as a mask, the polycrystalline silicon film 4a is etched to form the gate 4, and then the photoresist film 11 is removed. Then, using the gate 4 of the polycrystalline silicon film and the insulating film 2 for element isolation as a mask, arsenic is ion-implanted to n ^+.
The source 5 and the drain 6 of the region are formed on the surface of the silicon substrate 1.

Finally, as shown in FIG. 3 (f), if the insulating film 7, the source and drain electrodes 8a and 8b, and the insulating film 9 are formed by a normal process, the MIS of the first embodiment of the present invention can be obtained.
A semiconductor device including a FET can be obtained.

〔The invention's effect〕

As described above, according to the present invention, the gate insulating film is formed of TEOS.
By using only a film, it is possible to control the deterioration of electrical characteristics in a radiation environment, and therefore it is possible to obtain a highly integrated semiconductor device having high reliability even in a radiation environment. There is.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a sectional view of a technique related to the present invention, and FIGS. 3 (a) to (f) are one embodiment of a method for manufacturing a semiconductor device of the present invention. FIG. 6 is a cross-sectional view of a semiconductor chip shown in the order of steps for explaining an example. 1, 1 '... Silicon substrate, 2, 2a, 2b ... Insulating film,
3, 3 ', 3a, 3a' ... TEOS film, 3 ", 3a" ...
Insulating film, 4, 4 '... Gate, 4 "... Ground electrode, 4a ... Polycrystalline silicon film, 5, 5', 5" ... Source, 6, 6 '...
Drain, 7, 7 '... Insulating film, 8a, 8a' ... Source electrode, 8b, 8b '... Drain electrode, 9 ... Insulating film, 10,
11 ... Photoresist film.

Claims (1)

[Claims] 1. A semiconductor device having a field effect transistor formed on a semiconductor substrate, wherein a gate insulating film of the field effect transistor is composed only of an oxide film grown using tetraethylorthosilicic acid. Semiconductor device.