JPH0522387B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming active regions separated by an insulating film on the surface of a semiconductor substrate.

[Conventional technology]

A conventionally used method of this type is shown in FIG. That is, FIG. 3 shows a method of forming an active region by selective epitaxial growth technology. First, an insulating film 2 such as a silicon oxide film is formed on the main surface of a silicon substrate 1, and then a third Figure A), the insulating film 2 is left only in a predetermined area by photolithography (Figure 3B), and then an epitaxial layer 3 with approximately the same thickness as the insulating film is formed in the area where the insulating film is removed. This is used as an active region (Fig. 3C).

[Problem that the invention seeks to solve]

However, in this selectively formed epitaxial layer 3, during crystal growth,
As shown with marks, lattice defects are likely to be introduced near the interface with the insulating film 2, and the epitaxial layer 3
When a semiconductor element is formed in the defect area 4,
However, there are drawbacks such as abnormal diffusion of impurity atoms along the path and an increase in leakage current.
This defect region 4 extends 0.5 μm from the interface between the insulating film 2 and the epitaxial layer 3 into the epitaxial layer.
In severe to severe cases, the distance could reach up to about 2 μm.

The present invention was made to solve these problems, and its purpose is to create a semiconductor device that can eliminate defective regions from the active region by epitaxial growth after forming a selective insulating film. The purpose is to provide a manufacturing method.

[Means for solving problems]

In order to achieve such an object, the present invention applies a selective oxidation method to an epitaxial layer formed after forming a first insulating film in a predetermined region,
The second insulating film is formed on the surface near the interface with the first insulating film.

[Effect]

Defect regions generated near the interface with the first insulating film during epitaxial layer formation are covered with the second insulating film, making it possible to obtain a defect-free active region.

〔Example〕

FIG. 1 is a process sectional view showing an embodiment of the present invention. In the same figure, an insulating film 2 made of a silicon oxide film is formed in exactly the same manner as in the conventional example described above.
An epitaxial layer 3 is formed on the surface of the silicon substrate 1 from which this has been removed by selective epitaxial growth (FIGS. 1A to 1C). Thereafter, in this embodiment, a selective oxidation method is further applied to this epitaxial layer 3 to form a selective oxide film 5 on the surface near the interface with the insulating film 2 (FIG. 1D). As a result,
The portion of the epitaxial layer 3 whose surface is not covered by the selective oxide film 5 is formed as an active region, but as described above, the width of the defect region 4 is usually 0.5μ.
Since the distance D between the edge of the active region and the edge of the buried insulating film 2 is at least approximately
It is desirable that the thickness be 0.5 μm or more.

This made it possible to prevent defective regions from covering the active region, eliminate abnormal diffusion of impurity atoms, and reduce leakage current.

Next, another embodiment will be described based on FIG.
First, the steps up to the step of selectively removing the insulating film 2 made of a silicon oxide film formed on the surface of the silicon substrate 1 are exactly the same as in the previous embodiment (FIGS. 2A and 2B). The difference is that an epitaxial layer 3A is formed to have a thickness greater than that of the next insulating film 2, and the insulating film 2 is buried with the epitaxial layer 3A. In this case, a defective region 4 is formed near the interface with the side surface of the insulating film 2, and a defective region 4A is also formed near the interface with the top surface of the insulating film 2 (FIG. 2C).

Next, the epitaxial layer 3A on top of the buried insulating film 2 is oxidized by a selective oxidation method,
A selective oxide film 5A is formed (FIG. 2D). In this case as well, it is desirable that the distance D between the end of the epitaxial layer 3A in the active region not covered by the oxide film 5A and the end of the buried insulating film 2 is 0.5 μm or more; As a result, abnormal diffusion of impurity atoms is eliminated, and leakage current is also reduced.

Such a method according to the present invention can be commonly used as a prerequisite active region formation technique when forming various semiconductor devices using a silicon substrate. Note that the conductivity types of the substrate and the epitaxial layer have not been specifically mentioned, but this is because the present invention can be applied regardless of these conductivity types, and the conductivity types of both may be P type or N type. They may be the same or different. Also,
It goes without saying that the first insulating film 2 is not limited to a silicon oxide film, but may be another insulating film such as a silicon nitride film.

〔Effect of the invention〕

As explained above, according to the present invention, selective oxidation is applied to the epitaxial layer formed after forming the first insulating film in a predetermined region, so that the first insulating film is formed on the surface near the interface with the first insulating film. By forming the second insulating film, the portion of the epitaxial layer not covered by the second insulating film can be obtained as a defect-free active region.

[Brief explanation of the drawing]

FIG. 1 is a process sectional view showing an embodiment of the present invention;
FIG. 2 is a process sectional view showing another embodiment of the present invention;
FIG. 3 is a process cross-sectional view showing a conventional method of manufacturing a semiconductor device. DESCRIPTION OF SYMBOLS 1... Silicon substrate, 2... Insulating film (first insulating film), 3, 3A... Epitaxial layer, 4, 4
A...Defect area, 5,5A...Selective oxide film (second
insulation film).

Claims (1)

[Claims] 1. A step of forming an isolation insulating film in a predetermined region on a semiconductor substrate, and a step of forming a semiconductor layer on this semiconductor substrate using an epitaxial growth method,
By applying a selective oxidation method to the formed epitaxial semiconductor layer, a selective oxide film is formed on the surface near the interface with the isolation insulating film, and the portion of the epitaxial semiconductor layer not covered by this selective oxide film is used as an active region. a step in which the active region is separated from the interface between the isolation insulating film and the epitaxial semiconductor layer.
A method for manufacturing a semiconductor device, characterized in that the selective oxide films are formed at a distance of 0.5 μm or more.