JPH01151244A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a smooth device isolation layer without a stepped part and a constricted part by a method wherein, while a side wall is formed, a polycrystalline silicon film left only inside a groove is transformed into an oxide film by thermal oxidation. CONSTITUTION:A semiconductor substrate 100 is thermally oxidized; then, a silicon nitride film 103 and polycrystalline silicon 104 are formed; an organic high-polymer film 105 is spin-coated. The surface is etched uniformly; a reactive ion etching operation is executed by making use of an organic high-polymer film 106 left inside a groove as a mask in such a way that the polycrystalline silicon 104 forms side walls along side faces of the groove and is left inside the groove. After the organic high-polymer film 106 has been removed, the polycrystalline silicon 104 left inside the groove is oxidized in steam at, e.g., 950 deg.C; an insulator layer 107 is formed Inside the groove. Because, during this process, the polycrystalline silicon is left as the side walls at the side walls of the groove, a smooth isolation region without a constricted part and a stepped part can be formed at the side walls of the groove after oxidation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming an m region for an element.

[Conventional technology]

Conventionally, in the LOCO3 method used as an element isolation method, not only is there a large difference in dimension conversion due to the lateral spread of the oxide film, but it is also impossible to achieve isolation of 1 μm or less. Therefore, there is a ``grooving element isolation method J'' in which a groove is formed in a semiconductor substrate and polycrystalline silicon is buried in the groove and converted into an insulator by oxidation, as disclosed in Japanese Patent Laid-Open No. 188241/1981.

[Problem that the invention seeks to solve]

The trenching element isolation method described above leaves the polycrystalline silicon in a flat state within the trench, and therefore has the disadvantage that the oxide film after oxidizing this tends to leave gaps and constrictions on the upper side of the trench. An object of the present invention is to provide a semiconductor device that does not have the above-mentioned drawbacks.

[Means for solving problems]

The method for manufacturing a semiconductor device of the present invention includes: a) forming a groove in an arbitrary region on a semiconductor substrate; b) forming a thermal oxide film on the semiconductor substrate; and (c) then forming a silicon nitride film. d) sequentially forming a polycrystalline/silicon film having a thickness approximately half of the depth of the groove minus the thickness of the silicon/nitride film; and e) the step of forming the polycrystalline silicon film. f) removing the polycrystalline silicon film left only within the groove while forming a side call along the peripheral side surface of the groove; It is characterized by comprising a step of forming an oxide film by thermal oxidation.

〔Example〕

The present invention will be described in detail below based on examples.

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

First, as shown in FIG. 1(a), w should be an element isolation region.
i region by photoetching, for example, using alt gas at 5 mtOrr and 1 w/cm RF power,
The semiconductor substrate 100 is etched by 0.8 μm to form the groove portion 10.
form 1.

Next, as shown in FIG. 1(b), the semiconductor substrate is thermally oxidized, for example, at 1000°C in an atmosphere of 400°C, and then the silicon nitride film 103 is formed by 1000°C, and the polycrystalline silicon (104) is formed into a deep groove. A film of 3,500 layers, which is half of the silicon nitride film of 0.8 μm minus 0.1 μm of the silicon nitride film, is formed by, for example, vapor phase epitaxy, and the organic polymer film 105 is spin-coated. For example, a photoresist film, a polyimide film, an organic silicon film, etc. are used.

Then, as shown in FIG. 1(c), the surface is uniformly etched in a plasma atmosphere, leaving the organic polymer film 106 only inside the grooves.

Next, as shown in FIG. 1(d), the above-mentioned "machine polymer m10θ
Using this as a mask, the polycrystalline silicon 104 is etched by reactive ion etching so that side calls are made along the sides of the groove and it remains inside the groove.

Then, as shown in FIG. 1(e), the organic polymer film 106 is
After removing the polycrystalline silicon 104 remaining inside the groove, the polycrystalline silicon 104 remaining inside the groove is oxidized, for example, in water vapor at 950° C. to form an insulating layer 107 inside the groove.

At this time, since the polycrystalline silicon remains as a side call on the side surfaces of the groove, a smooth separation region can be obtained after oxidation without leaving any constrictions or differences on the side surfaces of the groove.

C. Effects of the Invention] As explained above, according to the present invention, a semiconductor device with a dimensional conversion difference of almost 0, which is provided with a smooth element isolation layer without any difference or constriction at the joint between the minute region and the element region. is obtained.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(e) are process cross-sectional views showing one embodiment of the method for manufacturing a semiconductor device according to the present invention. 100...Semiconductor substrate 101...Groove portion 102...Oxide film 103...Silicon nitride film 104...Polycrystalline silicon 105...Organic polymer film 10G...・・Insulator layer or more t [person Seiko Epson Corporation

Claims (1)

[Claims] (a) Step of forming a groove in an arbitrary region on the semiconductor substrate; (b) Step of forming a thermal oxide film on the semiconductor substrate; and (c) Step of forming a silicon nitride film. (d) sequentially forming a polycrystalline silicon film having a thickness of approximately half the value obtained by subtracting the thickness of the silicon nitride film from the depth of the groove; (e) the polycrystalline silicon is (f) forming an oxide film by thermal oxidation of the polycrystalline silicon film left only in the groove; It is characterized by consisting of the process of
Manufacturing equipment for semiconductor devices.