JPS63185040A - Semiconductor device - Google Patents

Abstract

PURPOSE:To suppress the intrusion of impurities into a transistor channel region and to obtain an excellent element isolating characteristic, by embedding semiconductor layers having the same conductivity type as that of a semiconductor substrate in grooves, which are formed in the surface of a silicon semiconductor substrate, and electrically isolating elements. CONSTITUTION:P-type polycrystalline silicon films 8 are embedded in grooves 8 formed in the surface of a p<-> type semiconductor substrate. Thus elements are isolated. Not only the same element isolating characteristic as that of a conventional semiconductor device is obtained, but also intrusion of p<->type impurities into the channel region of a transistor can be eliminated. Therefore, the width of the gate of the transistor becomes the length determined by the element isolating region. Increase in threshold voltage value can be prevented even in the transistor, in which especially short gate width is required. Since polycrystalline silicon is embedded in the silicon grooves 2, an impurity forming step can be omitted, and the manufacturing process can be shortened. The p<->type polycrystalline silicon film 8 is formed on only the side wall part and the bottom wall part of each silicon groove 32. An insulating film 3 is embedded in the remaining part of each silicon groove 2, and thus the surface of the silicon semiconductor substrate can be flattened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a semiconductor device in which fine trench isolation can be realized without causing a narrow channel effect.

[Conventional technology]

2(a) and 2(b) are cross-sectional views showing conventional semiconductor devices, respectively, and FIG. 2(C) is 11c-1 of FIG. 2(al).
It is a top view which shows area 1c. In this figure, ■ is p
- type silicon semiconductor substrate, 2 is a groove formed on the surface of the silicon semiconductor substrate 1, 3 is an insulating film (for example, a silicon oxide film) embedded in the groove 2, and 4 is an opening of the groove 2 on the surface of the silicon substrate. 5 is a gate insulating region formed on the silicon semiconductor substrate 1. A polycrystalline silicon film 6 is formed on the gate insulating film 5 and serves as a gate electrode and wiring, and 7 is an n+ type impurity region formed on the surface of the silicon semiconductor substrate 1 and serves as a source and drain region.

In such a semiconductor device, due to the action of the p-type impurity t=IJjI4 formed on the surface of the silicon semiconductor substrate,
In addition to providing good electrical isolation between elements, good electrical isolation is also provided in the channel direction of the gate electrode 6, that is, in the direction along the dividing region 3, thereby improving the electrical isolation between the source and drain of the transistor. was possible.

[Problem that the invention seeks to solve]

In the conventional semiconductor device as described above, a p impurity region 4 is formed on the surface of the silicon substrate in order to electrically isolate between elements and between the source and drain. Since it is also formed under the electrode, the gate width of the transistor is effectively narrowed.
There was a problem in that the dark voltage of the transistor became high.

The present invention was made in order to solve the above-mentioned problems, and aims to provide a semiconductor device that can obtain good electrical isolation characteristics without substantially narrowing the gate width of a transistor. It is said that

[Means for solving problems]

In the semiconductor device according to the present invention, a semiconductor layer of the same conductivity type as the semiconductor substrate is embedded in a groove formed on the surface of a silicon semiconductor substrate to electrically isolate elements.

[Effect]

In this invention, a semiconductor layer of the same conductivity type as that of the semiconductor substrate is buried in a groove formed on the surface of a silicon semiconductor substrate to electrically isolate the elements, so that impurities enter the channel region of the transistor. Protrusion can be suppressed, and thereby even when a transistor with a narrow channel width is formed, an increase in dark value voltage can be prevented.

〔Example〕

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

FIG. 1(a) is a sectional view showing a semiconductor device according to an embodiment of the present invention, and FIG. 1(C) is an Ic-IC of FIG. 1(a).
FIG. 3 is a plan view showing the area. In this figure, the same reference numerals as those in FIG. Here, a polycrystalline silicon film (semiconductor layer) 8 of the same conductivity type as the silicon semiconductor substrate 1, that is, p-type, is embedded.

Next, the effects will be explained.

In the device of this embodiment, a p-type crystalline silicon film 8 is buried in the groove 2 formed on the surface of the p-type semiconductor substrate to isolate the elements, so that the same element isolation characteristics as the conventional semiconductor device can be obtained. p to the channel region of the transistor.
It is possible to eliminate the protrusion of type impurities, and for this reason, the gate width of the transistor is set to the length determined by the element isolation region, which prevents the dark voltage from increasing even in transistors that require a particularly short gate width. be able to.

In addition, in conventional semiconductor devices that are filled with an insulating film, an impurity region had to be formed around the silicon groove, but in this device, polycrystalline silicon is buried in the silicon groove 2, so the impurity formation process is not necessary. This can shorten the manufacturing process.

In the above embodiment, the silicon groove 2 is entirely filled with p-type child crystalline silicon, but this p-type child-crystalline silicon is effective only in the region in contact with the p-type silicon semiconductor substrate 1. As shown in FIG. 1(b), a p-type crystalline silicon film 8 is formed only on the sidewalls and bottom of the silicon groove 2, and the remaining part of the silicon groove 2 is filled with an insulating film 3 as before. The surface of the semiconductor substrate may be kept flat.

〔Effect of the invention〕

As described above, according to the semiconductor device according to the present invention,
A semiconductor layer of the same conductivity type as that of the semiconductor substrate is embedded in a groove formed on the surface of a silicon semiconductor substrate to electrically isolate the elements. Therefore, impurity transistors generated when the silicon groove is used for element isolation are eliminated. This has the effect of suppressing the protrusion into the channel region and providing good element isolation characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a diagram for explaining a conventional semiconductor device. In the figure, 1 is a p-type silicon semiconductor substrate, 2 is a groove formed on the surface of the semiconductor substrate, 3.5 is a silicon oxide film,
6.8 is a polycrystalline silicon film, and 7 is an n impurity region. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) In a semiconductor device having a groove formed on the surface of a semiconductor substrate for isolating elements, a semiconductor layer having the same conductivity type as the semiconductor substrate is embedded in the groove to electrically isolate the elements. A semiconductor device characterized by: (2) The semiconductor layer is a semiconductor film formed along the inner wall surface of the trench, and the trench is filled with the semiconductor film and an insulating film filled thereon. A semiconductor device according to claim 1.