JPH0332053A - Semiconductor device - Google Patents

Abstract

PURPOSE:To enable a pellet to be made small by using nondoped polysilicon as the dielectric of a capacitor formed on a semiconductor substrate. CONSTITUTION:A polysilicon electrode 6 is formed as a first electrode on a field oxide film 3 formed on a semiconductor substrate 1, and then after formation of a thin oxide film, nondoped silicon 4 is accumulated by sputtering method. Next, after oxidation of the side face, a polysilicon electrode 6 is formed. Since the permittivity of nondoped polysilicon is about 12 times, the capacitance per unit area can be made three times that in the case where the capacitor is formed of an oxide film, and the area becomes about 1/3. Moreover, since a polysilicon electrode insulated from the board is used without using a diffusion layer as a first electrode, other element can be formed at the diffusion layer, and the pellet can be reduced further.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a capacitor formed on a semiconductor substrate and using an insulator as a dielectric, and particularly to a semiconductor device having a capacitor using non-doped polysilicon as well as an insulator. Regarding.

2. Description of the Related Art Conventionally, a capacitor formed on a semiconductor substrate of this type has a diffusion layer 12 formed by introducing impurities into a semiconductor substrate 11 by ion implantation or thermal diffusion, and aluminum, as shown in FIG. Oxide 11113 formed by thermal oxidation or CVD and sandwiched between electrodes 15 (hereinafter abbreviated as aluminum) was used as a dielectric.

Problems to be Solved by the Invention The conventional capacitor formed on a semiconductor substrate as described above uses an oxide film as a dielectric material, and therefore has a dielectric constant of 3.
Since it is small at 9, the capacitance per unit area (C)
For example, if an attempt was made to form a 10PF capacitor with an oxide film thickness of 1000, the area of the capacitor would be approximately 30001 m2, which would occupy a fairly large area of the pellet.

The present invention has been made in view of the above-mentioned conventional situation,
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel semiconductor device that eliminates the above-mentioned drawbacks inherent in the conventional technology and allows the pellet to be made smaller.

Differences between the invention and the prior art In contrast to the above-mentioned conventional capacitor, which is an element of a semiconductor integrated circuit formed on a semiconductor substrate using an oxide film as a dielectric, the present invention uses non-doped polysilicon as a dielectric. There is a difference.

Means for Solving the Problems In order to achieve the above object, a capacitor, which is an element of a semiconductor integrated circuit formed on a semiconductor substrate using an insulator according to the present invention as a dielectric, has non-doped polysilicon as an insulator. It is characterized by the use of

Embodiments Next, preferred embodiments of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention.

Referring to FIG. 1, P-type impurities are introduced into an n-type semiconductor substrate 1 by ion implantation or thermal diffusion. (P-type diffusion layer), then form a thin field oxide JII 3, and then deposit non-doped polysilicon 4 by sputtering. Next, perform side oxidation of the polysilicon 4, and finally form aluminum pole 5. .

FIG. 2 is a longitudinal sectional view showing a second embodiment of the present invention.

Referring to FIG. 2, a polysilicon electrode 6 is formed as a first electrode on a field oxide H3 formed on a semiconductor substrate 1, and a thin oxide film is formed as in the first embodiment. Non-doped polysilicon 4 is deposited, and after side oxidation, polysilicon electrode 6 is formed.

In this second embodiment, since the diffusion layer is not used as the first polarization and a polysilicon electrode insulated from the substrate is used, other elements can be formed in the diffusion layer, and the - layer pellet can be formed. Effective in downsizing.

As described in detail, according to the present invention, non-doped polysilicon is used as the dielectric of a capacitor formed on a semiconductor substrate, and since the dielectric constant of non-doped polysilicon is about 12, the unit area can be reduced. The capacitance (C) per unit can be approximately three times that of a capacitor formed using an oxide film.For example, if a 10 pF capacitor is formed using polysilicon with a film thickness of 1000 mm, the area of the capacitor will be approximately 940 mm. #+1'', which is about 1/3 of that in the case where the capacitor is formed with an oxide film, and it is possible to achieve the effect of reducing the size of the pellet.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view showing a second embodiment of the present invention, and FIG.
The figure is a longitudinal sectional view showing a conventional capacitor of this type. 1.11... N-type semiconductor substrate, 2, 12... P-type diffusion layer, 3, 13... Field oxide film, 4... Non-doped polysilicon, 5.15... Aluminum electrode, 6・
・Polysilicon electrode

Claims (1)

[Claims] 1. A semiconductor device characterized in that, in a capacitor that is an element of a semiconductor integrated circuit formed on a semiconductor substrate using an insulator as a dielectric, non-doped polysilicon is used as the insulator.