JPS61228653A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To stabilize isolation withstanding voltage and to make it possible to control the isolating width between active layers highly accurately with good reproducibility, by providing a lateral-growth preventing layer comprising, e.g., an Si3N4 layer between the active layers formed by an epitaxial growing method. CONSTITUTION:A semiconductor substrate, e.g., a P-type silicon substrate 1 is prepared. An isolating insulating film, e.g., a silicon oxide film 2, is formed on the main surface of the substrate by a thermal oxidation method. An Si3N4 film is further formed thereon by a pressure reduced CVD method. Then, the Si3N4 film is patterned by a photoengraving method. Thereafter, a lateral-growth preventing film, e.g., an Si3N4 film 10, is formed on the entire surface of the silicon substrate 1 again. Then, an active layer 3 is formed on the silicon substrate 1 by an epitaxial growing method. Finally an N-MOST is formed on the part of the active layer 3. Thus, each active layer is positively isolated, and the isolation withstanding voltage of the transistor, which is formed on each active layer, does not become unstable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and particularly to isolation of elements such as transistors and diodes.

[Conventional technology]

Single-selective oxidation and epitaxial growth methods are widely used as well-known techniques in the manufacture of integrated circuit devices. 82
The figure is a partial sectional view when an n-channel transistor (abbreviated as n-MO8T) is manufactured by a conventional method. Namely.

First, a silicon oxide film 2, which is an isolation insulating film, is formed on a silicon substrate 1 having a p-type high specific resistance, for example, 100 to 300 Ω/scars, by a well-known selective oxidation method.

After that, by epitaxial growth method, for example, 5 to 15
An active layer 3 of Ω・α is formed, and n-MO8T' is formed in this part.
91: Formation S6゜n -M OS T f! , M Eva is produced by the following method.

A gate oxide film 4 is formed on the active layer 3, and n-MO8
In order to control the threshold voltage of T, horn (B)v ions are implanted into the channel region 8. Next, a polysilicon layer 5v which becomes a gate is formed on the channel region 8. Subsequently, the NFI source region 6 and drain region 7Y are formed by ion implantation of phosphorus (P) or arsenic (As).

[Problem that the invention seeks to solve]

However, such conventional methods have the following drawbacks. That is, as the density of integrated circuits decreases, the density of the active layers 3 formed on the silicon substrate 1 increases proportionally, and the separation width 9 between the active layers 3 inevitably becomes narrower. becomes difficult.

This causes poor isolation withstand voltage between elements.

The manufacturing yield of integrated circuits has been extremely reduced.

This invention was made to solve the above-mentioned problems, and aims to control the separation width between active layers by epitaxial growth with high precision and good reproducibility.

[Means for solving problems]

The method for manufacturing a semiconductor device of the present invention is to provide a lateral growth prevention layer of 1, for example, 811NJ between active layers formed by epitaxial growth, and to control the distance width between each active layer formed by epitaxial growth to stabilize the isolation breakdown voltage5. It is something to do.

[Effect]

In this invention, by providing a lateral growth prevention layer, it is possible to reliably prevent lateral growth of the active layer by epitaxial growth, and the breakdown voltage between n-MO8T is improved.

〔Example〕

FIGS. 1(a) to 1(・) are cross-sectional views showing the state of an embodiment of the present invention at the main meal process stage. First, FIG.
A K, semiconductor substrate, for example, a silicon substrate 1v of pIJl is prepared as in a), and an isolation insulating film 1, for example, a silicon oxide film 2 is formed on its main surface by thermal oxidation, and further 81. N, after forming the film by low pressure CVD method, this 81. N, pattern the film by photolithography. After that, this 81. The silicon oxide film 2t is etched using the N and film t masks to remove the unnecessary silicon oxide film 2'lL-, and a pattern of the silicon oxide film 2 is formed.As shown in FIG. 1(b), Again, a lateral growth prevention film, for example 81. A film 111 of 81.N is formed, and as shown in FIG. N, membrane 1
At this time, the growth thickness and remaining area of the Si, N, and film 10 are determined by the growth thickness and dimensions of the epitaxial growth method performed in a later step. Thereafter, as shown in FIG. 1(d), an active layer 3 is formed on the silicon substrate 1 by epitaxial growth.

Next, the silicon oxide film 2 is removed as shown in FIG.

A polysilicon layer 11 is formed in the portion not covered by the film 10, but this portion may be removed by etching if necessary.

The active layer 3 is separated into individual parts by the above-described process. Finally, n-MO8Tv is formed in this active layer 30 portion. Here, aqi4 is used especially in cases where the dimension is relatively large.

As n-M O8T develops into VLSIs, the isolation breakdown voltage between elements becomes unstable, but in the isolation step of the process, the lateral growth prevention film 81. N4
By providing the membrane 10't- this problem is completely solved.

Although the above embodiment has been described for the purpose of electrically isolating n-MO8T, it is clear that the present invention can also be used in a process that requires dimensional accuracy between elements when manufacturing an integrated circuit V.

〔Effect of the invention〕

As explained above, this invention forms a desired pattern of isolation insulator 1 on a semiconductor substrate, and then forms Ky! After forming the lateral growth prevention film in the desired IF pattern, the active layer is formed by epitaxial growth, so each active layer is reliably separated, and the isolation breakdown voltage of the transistor formed in each active layer is ensured. The advantage is that it does not become stable.

[Brief explanation of drawings]

FIGS. 1(a) to (@) are process cross-sectional views for explaining one embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the structure of a conventional n-M08T. In the figure, 1 is a silicon substrate, 2 is a silicon oxide film,
3 is an active layer formed by epitaxial growth. 10 is SL, N, membrane. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Masuo Oiwa (2 others) Figure 1 Figure 1 Figure 2

Claims (1)

[Claims] In the method for manufacturing a semiconductor device, in which an isolation insulating film having a desired pattern is formed on a semiconductor substrate, and then active layers having different electrical properties are grown on the semiconductor substrate between the isolation insulating films. After forming a lateral growth prevention layer on the insulating film for preventing lateral growth of the active layer,
A method of manufacturing a semiconductor device, characterized in that the active layer is formed by epitaxial growth.