JPS5916340A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To enable to isolate microstructured elements by a method wherein an oxide film is formed by oxidizing a substrate, which film is selectively etched, Si is epitaxially grown thereon, which is coated with resist of low viscosity, thus the polycrystalline Si film is etched, and thereafter the resist on the single crystal film is removed. CONSTITUTION:The ion implantation of channel stopping impurity is performed to the P type (100) semiconductor substrate 1, next the substrate 1 is treated in oxidizing atmosphere, and accordingly the oxide film 2 is formed at the same surface layer part simultaneously with a P<+> type diffused layer 3. Next, the resist pattern is formed by photolithography, and the oxide film 2 is etched by reactive ion etching. Thereafter, epitaxial growth is performed on the substrate 1 via the pattern of the oxide film 2. Thereat, the polycrystalline Si film 4 is grown on the oxide film 2, and the single crystal Si film on the surface of the substrate 1, respectively. The surface impurity densities of the Si layers 4 and 5 are approximately equal to the substrate density. The single crystal Si film 5 must be thinner than the oxide film 2.

Description

[Detailed description of the invention] The present invention relates to a method of manufacturing a semiconductor device.

Due to recent advances in semiconductor integrated circuit technology, the size of transistors has ranged from 2 to 3 .mu.m in line width, and it has become possible at the research stage to have line widths of 2 .mu.m or less. However, even if the transistor size becomes smaller, unless the isolation region becomes smaller, high density integrated circuits (hereinafter referred to as LSIs) cannot be realized. In the currently used selective oxidation method, there is a protrusion of the oxide film into the active region called a bird's peak, which makes the width (W) of the transistor smaller than the design and prevents miniaturization, but in MO3LSI, It causes a kind of narrow channel effect or reduces the transfer conductance. Current transistor size 20
For a thickness of ~30 μm, element isolation can still be achieved by selective oxidation, but for a thickness of 10 to 20 μm or less, this becomes difficult due to bird's beaks.

The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a semiconductor device that enables miniaturized isolation between elements.

In the method of the present invention, a semiconductor substrate is first oxidized to form an oxide film, the oxide film is selectively etched by photoetching or the like, and silicon is epitaxially grown on the oxide film. However, in this case, it is generally known that a polycrystalline silicon film grows on the oxide film -J-, and a single crystal silicon film grows on the surface of the semiconductor substrate. Next, on top of this, a low viscosity (
Apply a resist of 30 cp or less. In this way, the resist with a lower viscosity becomes thinner on polycrystalline silicon than on single crystal silicon because of steps caused by the presence of an oxide film, and in reality, the film thickness is about 1/3 or less.

Next, only the resist on the polycrystalline silicon film is etched using oxygen plasma, then the polycrystalline silicon film is etched, and then the resist on the single crystal film is removed. By doing this, the oxide film can be filled with a suitable size on the silicon substrate, and the precision of the method is good, and device isolation without bird's beaks can be achieved.

Hereinafter, one embodiment of the present invention will be described in more detail with reference to the drawings. 1 to 6 are process cross-sectional views according to the present invention. For example, to explain the element isolation of MOS-LSI, as shown in Figure 1, p-type (100) resistivity is 8 to 12 Q.
-cm semiconductor substrate 1, channel stop impurity (boron) is ion implanted at B+, 30KV, 2X
1013C,” carried out under the condition of -2.

Next, this substrate 1 was placed in an oxidizing atmosphere (1000° C.).

An oxide film 2 with a thickness of 10 μm is formed on the same surface layer, and at the same time a p+ type diffusion layer 3 is formed. Next, as shown in FIG. 2, a resist pattern is formed by photolithography, and the oxide film 2 is etched by reactive ion etching. Thereafter, as shown in FIG. 3, epitaxial growth is performed on the substrate 1 through the pattern of the oxide film 2. At this time, a polycrystalline silicon film 4 with a thickness of 0.8 μm is formed on the oxide film 2, and a single crystal silicon film 6 is formed on the surface of the substrate 1.
grows to a thickness of 0.8 μm. It is assumed that the surface impurity concentration of the silicon layers 4 and 50 is approximately equal to the substrate concentration. It's a size.
Single crystal silicon film 5 must be thinner than oxide film 2. This is because the oxide film 2. This is because near the boundary of the silicon film 5, a portion of the oxidized OI2'' becomes a single crystal, which affects etching.

Next, as shown in FIG. 4, a resist 6 having a low viscosity, for example, 30 cp or less, is applied to the epitaxially grown surface. In this case, the resist 6 of the silicon film 5'' is
There are about 8,000 people on the grassland, which is about 1/3 of the 2,000 to 3,000 people on the polycrystalline silicon film 4, and the resist 6 on the polycrystalline silicon film 4 is removed by the 02 plasma as shown in FIG. remove. In this case, the value of single crystal silicon is 5,000 to 6,000. Furthermore, in order to increase the thickness of the resist film on this single crystal silicon film 6, it is necessary to use a resist with a lower viscosity (
30 cp or less) is effective. This is 1/
Considering the resist film thickness required as a mask to remove the polycrystalline silicon film of jm, it is at least 5000~6.
This is because a thickness of 000 Å or more is necessary. Next, using the remaining resist 6 as a mask, the polycrystalline silicon film 4 of the oxide film 2''
plasma etching.

Finally, as shown in FIG. 6, the resist 6 is removed to complete element isolation. In this way, the portion of the single crystal noricon layer 5 is separated by the oxide film 2, and this portion has MO3+
- transistors can be formed;

The following two steps can also be applied to device isolation of bipolar trans/stars, except for the p+1 diffusion layer 3 for the channel transistors.

According to the present invention, elements can be isolated according to the resist pattern dimensions, and since the oxide film for element isolation is embedded in single crystal silicon, the surface is flat and can be easily achieved by selective oxidation. The present invention is very effective as an element isolation method because there is no noise beak that would otherwise occur.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 6 are process cross-sectional views showing the method according to the present invention. 1... Semiconductor substrate, 2... Oxide film, 4
. . . Polycrystalline silicon layer, 5 . . . Single crystal silicon layer, 6@.1II11 resist layer.

Claims (2)

[Claims] (1) forming an oxide film on one main surface of the semiconductor substrate;
selectively opening the oxide film to expose the surface of the semiconductor substrate, and simultaneously growing an epitaxially grown semiconductor single crystal film on the exposed surface of the semiconductor substrate and a semiconductor polycrystalline film on the oxide film by vapor phase growth. A step of growing the photoresist, a step of applying a photoresist on the entire surface, a step of removing the photoresist on the polycrystalline film, and a step of removing the resist with the remaining polycrystalline film as a mask. A method for manufacturing a semiconductor device. (2) The viscosity of the photoresist is 30 cp or less