JPS61187358A - Semiconductor device - Google Patents

Abstract

PURPOSE:To ensure a higher dielectric strength for capacitive elements and to allow them to occupy but smaller areas by a method wherein a silicon nitride film is sandwiched as a dielectric film between electrodes when capacitive elements of a piled-electrode design are constructed on a semiconductor substrate. CONSTITUTION:A field oxide film 12 is formed to cover the surface of an Si substrate 11 and, on the film 12, a first electrode 13 is built to prescribed dimensions. The entire surface is then covered by a first Si3N4 film 14. Next, thereon, a second electrode 16 is built, approximately similar in dimension to the first electrode 13. The entire surface is then covered by a second Si3N4 film 15, to be further covered by an electrode film 17. After this, an electrode line 18 is led from the electrode 16, an electrode line 19 from the electrode film 17, and an electrode line 20 from the electrode 13. The capacity generated between the electrode lines 18 and 19 and between 19 and 20 are used as capacitive elements. With the dielectric coefficient of an Si3N4 film being three times as large as that of an SiO2, integration is greatly enhanced when the thickness is increased of the Si3N4 films, and element capability may be realized to withstand higher voltages and the areas the capacitive elements occupy may be smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a capacitor in a semiconductor device.

[Conventional technology]

Conventionally, a capacitor in a semiconductor device has generally had a structure as shown in FIG.

That is, a field oxide film 2. is formed on the surface of a silicon substrate 1. Diffusion layer 5. Gate oxide film 4. An electrode film 6 is formed,
It has been customary to use the capacitance between the diffusion layer 3 and the electrode wire 6.7 of the electrode film 5.

[Problem that the invention seeks to solve]

However, the conventional technology has problems such as the gate oxide film being thin and having a low dielectric breakdown voltage, and the area occupied by the capacitor being large, making it unsuitable for high integration.

[Means for solving problems]

In order to solve the problems of the prior art, the present invention has the following features:
A capacitor having a stacked electrode structure in a semiconductor device is characterized in that at least a silicon nitride film is used as a dielectric film.

〔Example〕

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

FIG. 2 is a sectional view of a capacitor portion in a semiconductor device showing an embodiment of the present invention. That is, silicon substrate 1
1 has a field oxide film 12 and a first electrode film 15 on its surface.
．． First silicon nitride film 14, second electrode film 16. Second
A silicon nitride film 15 and a third electrode film 17 are formed, and an electrode line 18 from the second electrode film 16 and an electrode IIi! from the first electrode film 13 and the third electrode film 17 are formed. 20.
19 will be used as a capacitor.

Note that the first and second silicon nitride films 14 and 15 do not necessarily have to be a single layer of silicon nitride, but may have, for example, a multilayer structure of a silicon oxide film and a silicon nitride film, or a tantalum oxide film and a silicon nitride film. It goes without saying that the present invention is applicable to combinations of multilayer structures and the like.

〔Effect of the invention〕

By using at least a silicon nitride film as the dielectric film in a capacitor having a stacked electrode structure in a semiconductor device as in the present invention, the dielectric constant of the silicon nitride film is three times higher than that of a silicon oxide film. The dielectric film thickness can be increased, the dielectric strength can be increased, and the area occupied by the capacitor can be reduced, resulting in higher integration.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a capacitor in a semiconductor device according to the prior art, and FIG. 2 is a sectional view of a capacitor in a semiconductor device according to an embodiment of the present invention. 1.11...Silicon substrate 2.12...Field oxide film 4...
Gate oxide film 3...Diffusion layer 14.15...Silicon nitride film 5.13, 16
．． 17... Electrode film 6.7.1B, 19.20.
・・・・・・Electrode wire top・

Claims (1)

[Claims] 1. A semiconductor device characterized in that, in a capacitor having a stacked electrode structure in a semiconductor device, at least a silicon nitride film is used as a dielectric film.