JPS61269330A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve dimensional accuracy, and to prevent the mixing of an impurity by etching the surface to size through anisotropic etching, coating the whole surface with a thin-film and evaporating the impurity for a channel stopper. CONSTITUTION:An N-type buried layer 2 is formed to a P-type single crystal silicon substrate 1. An N-type or P-type silicon layer 3 is grown on the surface of the layer 2 and the whole surface of the substrate 1 in an epitaxial manner. An silicon oxide film 6 and an silicon nitride film 7 are left only above the layer 2. A layer 3 section is etched in an anisotropic manner until thickness thereof is halved approximately. A thin-film 8 consisting of an silicon oxide film or an silicon nitride film is evaporated on the whole surface, a P-type impurity layer 4 is shaped, and the thin-film 8 composed of the silicon oxide film, etc. is removed extending over the whole surface. The layer 3 section not coated with the oxidation treating film 7 functions as an isolation oxide film 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a semiconductor integrated circuit using an oxide film separation method.

Conventional technology Semiconductor integrated circuits have recently seen higher frequencies, higher densities,
In order to reduce power consumption, an element isolation technique called an oxide film isolation method is often used. FIG. 2 is a sectional view of an element formed thereby. This structure consists of forming an N-type buried layer (2) of the opposite conductivity type on a P-type single crystal silicon substrate (1), and then epitaxially growing an N-type or P-type silicon layer (3) on top of this. After isotropically etching the peripheral portion of the silicon layer (3), excluding the portion located above the N-type buried layer (2), to a predetermined depth, a portion adjacent to the N-type buried layer (2) is etched. Separation area (substrate (1)
) and the periphery of the silicon layer (3)), a P-type impurity layer (
4), converting the remaining silicon layer in the previously etched portion into an oxide film (5), and forming the silicon layer (5) on the buried layer (2).
3) forms an island region.

Problems to be Solved by the Invention However, in such conventional manufacturing methods, the P-type impurity layer (
During the ion implantation in step 4), in order to prevent P-type impurities from entering the side surfaces of the N-type silicon layer (3) due to off-angle implantation, the side surfaces of the N-type silicon layer (3) are implanted by the off-angle implantation amount d. This was a major hindrance in increasing the density.

The object of the present invention is to obtain a pattern-through element without introducing P-type impurities for a channel stopper into the side surfaces of the N-type silicon layer on such a buried layer.

Means for Solving the Problems In order to solve the above problems, the method for manufacturing a semiconductor integrated circuit of the present invention includes forming a buried layer of the opposite conductivity type on a silicon substrate of one conductivity type consisting of P type or N type. a step of epitaxially growing the silicon layer of one conductivity type or the opposite conductivity type on the silicon substrate including the buried layer, leaving a portion of the silicon layer located on the buried layer and growing the silicon around it; a step of etching the layer anisotropically to a predetermined depth; a step of forming a thin film on the entire surface of the silicon layer consisting of a portion located on the buried layer and the etched portion around it; and a step of forming a thin film by ion implantation. This method includes the steps of forming an impurity of one conductivity type only in a silicon layer other than the silicon layer on the buried layer, removing the thin film, and converting a portion of the silicon layer into an oxide layer.

Function: According to this manufacturing method, the entire surface is etched with anisotropic etching, the entire surface is covered with a thin film such as a silicon oxide layer, and then the impurity for the channel stopper is vapor deposited, resulting in good dimensional accuracy and no impurities. A high-density, highly reliable device free from contamination is formed.

Embodiment An embodiment of the method for manufacturing a semiconductor integrated circuit according to the present invention will be described with reference to step-by-step cross-sectional views of FIGS.

First, as shown in Figure 1a, a P-type single crystal silicon substrate (1
), a silicon oxide film (not shown) with a thickness of 0.5 to 2 μm is formed, and using this as a mask, antimony (sb
) or selectively doped with arsenic (As) by spin-on method or ion implantation method to form an N-type buried layer (a).

Next, the entire silicon oxide film is removed, and then a P-type or N-type silicon layer (3 ) is epitaxially grown to a thickness of 0.5 to 2.0 μm, and then a silicon oxide film (6) with a thickness of 100 to 500 μm and a silicon oxide film (6) with a thickness of 500 to 1500 μm are formed over the entire surface of the silicon layer (3). After sequentially forming silicon nitride films (7), these films are selectively etched to leave the silicon oxide film (6) and silicon nitride film (7) only on the N-type buried layer (2). Next, as shown in Figure 1, the silicon layer (3) exposed by dry etching is anisotropically etched until its thickness is reduced to about half.Then, by CVD or the like, silicon oxide is etched. A thin film (8) of silicon nitride film or silicon nitride film is deposited to a thickness of 1000 to 5000 nm over the entire surface, and then a channel stopper (of poron) is ion-implanted only under the isolation region adjacent to the N-type buried layer (2). A P-type impurity layer (4) is then formed, and then the thin film (8) such as a silicon oxide film is completely removed.

After this, as shown in FIG. In addition to the film (5), an island region is formed by the silicon layer (3) surrounded by the isolation oxide film (5). and,
This island region becomes a portion forming elemental elements of a semiconductor integrated circuit.

In the method for manufacturing a semiconductor integrated circuit of the present invention described above, the epitaxial layer can be separated according to a pattern without introducing impurities.

Effects of the Invention According to the method of manufacturing a semiconductor integrated circuit of the present invention, even if etching is performed according to a pattern, impurities do not enter the side surfaces of the epitaxial layer, so a high-density, highly reliable device can be formed. .

[Brief explanation of drawings]

Figures 1a, b, and c are cross-sectional views of an embodiment of the present invention in the order of steps;
FIG. 2 is a cross-sectional view of an island region formed by an isolation oxide film formed by a conventional manufacturing method. (1)・・・・・・・・・・・・・・・・・・・・・
...P-type single crystal silicon substrate (2) ...
・・・・・・・・・・・・・・・・・・N-type buried layer (3)・・・・・・・・・・・・・・・・・・-
...N-type or P-type silicon layer (4)...
・・・・・・・・・・・・・・・・・・P-type impurity layer (5)・・・・・・・・・・・・・・・・・・・・・
......Isolation oxide film (6)...
・・・・・・・・・・・・・・・・・・ Silicon oxide film (
7)・・・・・・・・・・・・・・・・・・・・・
...Silicon nitride film (8)...
・・・・・・・・・・・・・・・ Silicon oxide or silicon nitride film

Claims (1)

[Claims] A step of forming a buried layer of an opposite conductivity type on a silicon substrate of one conductivity type consisting of P type or N type, and epitaxial growth of the silicon layer of one conductivity type or opposite conductivity type on the silicon substrate including the surface of the buried layer. a step of leaving a portion of the silicon layer located above the buried layer and anisotropically etching the silicon layer around it to a predetermined depth; and a step of etching the silicon layer around the silicon layer anisotropically to a predetermined depth; and a step of forming a thin film such as an oxide or nitride film on the entire surface of the silicon layer consisting of the etched portions thereof, and implanting impurities of one conductivity type only into the silicon layer other than the silicon layer on the buried layer by ion implantation. a step of forming the thin film; a step of removing the thin film; and a step of leaving a portion of the silicon layer on the buried layer as an island region and converting the other portion into an oxide layer. manufacturing method.