JPH05304203A - Fabrication of semiconductor device - Google Patents

Abstract

PURPOSE:To form a small area isolation region by depositing an amorphous semiconductor entirely on the surface of a semiconductor substrate while leaving an insulation film only on the surface of the semiconductor substrate and the side wall of opening and then performing annealing. CONSTITUTION:A first insulation film 2a is formed on the surface of a silicon substrate 1. The first insulation film 2a is then patterned into a predetermined shape and an opening 3 is made in the silicon substrate 1 through etching. A second insulation film 2b is then formed on the surface of the silicon substrate 1 including the opening 3 and subsequently etched so that the second insulation film 2b is left only on the side wall 3a of the opening. An amorphous silicon 4 is deposited entirely on the surface of the silicon substrate 1, which is then annealed and the amorphous silicon 4 is removed selectively from the surface of the silicon substrate 1 thus isolating the active region. This method realizes an isolation region having quite small area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device for isolating active regions of integrated circuits such as IC and LSI.

[0002]

2. Description of the Related Art Conventionally, a groove is formed on a silicon substrate,
Several fine separation techniques have been proposed in which an insulating film is selectively left on the side surface of the groove and the inside of the groove is filled with single crystal silicon. For example, in Japanese Patent Laid-Open No. 2-82551, FIG.
There is disclosed a method of manufacturing a semiconductor device as shown in FIG.

First, the semiconductor substrate 11 is patterned into a predetermined shape, and a recess 12 is formed in the semiconductor substrate 11 by etching.
To form. Then, an insulating film 13 is formed on the entire surface of the semiconductor substrate 11 in which the recess 12 is further formed.
Is etched back by anisotropic etching so that only the side wall of the recess 12 of the semiconductor substrate 11 remains. Then, single crystal silicon 14 having a thickness sufficiently thicker than the depth of the recess 12 formed in the semiconductor substrate 11 is deposited on the entire surface of the semiconductor substrate 11 (FIG. 3A).

Next, a flattening material 15 such as a resist is spin-coated to completely flatten the surface of the semiconductor substrate 11 (FIG. 3B). Then, the entire surface of the semiconductor substrate 11 is etched back to embed the single crystal silicon 14 in the recess 12 of the semiconductor substrate 11 (FIG. 3C). In addition, in Japanese Patent Laid-Open Nos. 2-214138 and 3-141660, FIG.
There is disclosed a method of manufacturing a semiconductor device as shown in FIG.

First, the opening 12 is formed in the silicon substrate 11 by the same method as described above, and then the silicon substrate 11 is formed.
After leaving the insulating film 13 only on the surface and the sidewall of the opening 12 (FIG. 4A), the opening 1 of the silicon substrate 11 is selectively formed.
2 grows single crystal silicon 14 (FIG. 4).
(B)).

[0006]

In the method of manufacturing a semiconductor device described above, the insulating film 13 is left only on the side wall of the recess 12 of the semiconductor substrate 11, the single crystal silicon 14 is deposited on the insulating film 13, and the resist or the like is planarized. In the method of depositing the material 15 and performing the etch back, it is necessary to make the planarizing material 15 a considerably thick film, and the planarizing material 15 is accompanied by the thickening of the film.
However, there were problems such as in-plane uniformity of wafer and decrease in throughput due to etchback for a long time.

Further, after forming the opening 12 in the silicon substrate 11 and leaving the insulating film 13 only on the surface of the silicon substrate 11 and the sidewall of the opening 12, the single crystal is selectively formed in the opening 12 of the silicon substrate 11. In the method of growing the silicon 14, the growth rate of single crystal silicon under the condition that the selectivity between the silicon substrate 11 and the insulating film 13 is perfect is extremely low, and is extremely unsuitable as a mass production technology. There was a problem.

The present invention has been made in view of the above problems, and is excellent in mass productivity without impairing flatness.
It is an object of the present invention to provide a method for manufacturing a semiconductor device capable of forming an element isolation region having an extremely small area.

[0009]

In order to solve the above-mentioned problems, according to the present invention, (i) a step of forming a first insulating film on the surface of a semiconductor substrate, (ii) the first insulating film Patterning to a predetermined shape and etching the semiconductor substrate to form an opening, (iii) forming a second insulating film on the surface of the semiconductor substrate including the opening, and then etching the sidewall of the opening. Leaving only the second insulating film, (iv) depositing an amorphous semiconductor on the entire surface of the semiconductor substrate, performing an annealing treatment, and then selectively removing the amorphous semiconductor on the semiconductor substrate, There is provided a method of manufacturing a semiconductor device including an active region, the active region being isolated.

In the present invention, examples of the first insulating film formed on the semiconductor substrate (for example, a silicon substrate) include SiO ₂ film and SiN film, and the SiO ₂ film is preferable. The film thickness is about 1500 to 2000Å. Further, as the second insulating film, for example, Si
Examples thereof include an O ₂ film and a SiN film, and a SiO ₂ film is preferable, and the film thickness thereof is about 2000 to 2500Å.
These insulating films are formed by a known method such as thermal oxidation or CVD.
It can be formed by a method or the like.

The opening formed in the region for forming the active region preferably has a depth of about 2500 to 3000Å and can be formed by a usual etching method such as trench etching. Further, the method of etching the first and second insulating films to leave the insulating film only on the surface of the semiconductor substrate and the sidewalls of the opening can be performed by a known method, for example, anisotropic etching.

In the present invention, the amorphous semiconductor can be formed by a known method, for example, the CVD method, and the method of single crystallizing the amorphous semiconductor is to bring the amorphous semiconductor into contact with the single crystal semiconductor to form N ₂ Alternatively, it can be achieved by annealing in an Ar atmosphere at atmospheric pressure and in a temperature range of about 1000 to 1100 ° C. for about 30 to 60 minutes. Then, after the amorphous semiconductor portion embedded in the opening is completely single-crystallized, only the amorphous semiconductor on the semiconductor substrate which is not single-crystallized is spin-etched by, for example, KOH or HF / HNO ₃ -based etchant. In this method, the change in Si concentration in the waste liquid is detected, and when the SiO ₂ on the surface is exposed, the supply of the etchant is stopped and the etching is selectively removed.

A desired semiconductor element can be formed in the active region separated by such a method.

[0014]

According to the above method, the opening is formed in the semiconductor substrate, the insulating film is left only on the surface of the semiconductor substrate and the sidewall of the opening, and then the amorphous semiconductor is deposited on the entire surface of the semiconductor substrate. Since the active region is separated by performing an annealing process and selectively removing the amorphous semiconductor on the semiconductor substrate, the amorphous semiconductor is easily monocrystallized in a self-aligned manner.

[0015]

EXAMPLE An example of a method of manufacturing a semiconductor device according to the present invention will be described with reference to FIGS. First, the silicon substrate 1 was oxidized to form a SiO ₂ film 2a as a first insulating film having a film thickness of about 2000 Å (FIG. 1A).

Simultaneously with patterning the SiO ₂ film 2a into a predetermined shape, the silicon substrate 1 was etched by about 3000 Å to form an opening 3 (FIG. 1 (b)). Then, after forming an oxide film of about 200 Å on the surface of the opening 3, the second insulating film Si, which is the second insulating film, is formed on the entire surface of the silicon substrate 1 including the opening 3 by the CVD method using SiH ₄ and O _2.
An O ₂ film 2b was formed on the order of 2500 Å (FIG. 1 (c)).
Then, the SiO ₂ film 2b is etched away by about 2500 Å by anisotropic etching until the silicon substrate 1 on the bottom surface of the opening 3 is completely exposed, and the SiO ₂ film 2 on the surface of the silicon substrate 1 and the opening of the silicon substrate 1 are removed. Side wall 3a S
Only the iO ₂ film 2 was left (FIG. 1 (d)).

Next, about 3000 Å of amorphous silicon 4 is deposited on the entire surface of the silicon substrate 1 (see FIG. 1).
(E)), annealing treatment was performed at about 1100 ° C. for about 60 minutes in an N ₂ atmosphere. By this annealing treatment, the amorphous silicon 4 is single-crystallized from the portion in direct contact with the silicon substrate 1, and the amorphous silicon 4 buried in the opening 3 is almost completely single-crystallized (FIG. 2).
(F)). Then, the non-single-crystallized amorphous silicon 4 deposited on the silicon substrate 1 through the SiO ₂ film 2 was selectively removed (FIG. 2G).

Then, the SiO ₂ film 2 formed on the silicon substrate 1 was selectively removed by etching about 2000 Å (FIG. 2 (h)). This allows
It was possible to form an extremely small active area separated by the SiO ₂ film 2. Then, impurities are diffused into the silicon substrate 1 and distributed to a desired conductivity, and then a SiO ₂ film of about 100 Å which is a gate oxide film is formed on the silicon substrate 1.
The gate electrode 7 is formed by forming the film 6 and further depositing about 3500 Å polysilicon on the SiO ₂ film 6 and patterning it into a predetermined shape (FIG. 2).
(I)). Then, using the gate electrode 7 as a mask, for example, As ions (7) as impurities are added at 80 KeV, 3 ×.
After implanting at 10 ¹⁵ ions / cm ² , heat treatment was performed at a temperature of 800 ° C. for 1 hour to form the source / drain regions 8 (FIG. 2 (j)), and the semiconductor device was prepared.

[0019]

According to the method of manufacturing a semiconductor device of the present invention, an opening is formed in a semiconductor substrate, and an insulating film is left only on the surface of the semiconductor substrate and side walls of the opening, and then on the semiconductor substrate. An amorphous semiconductor is deposited on the entire surface, an annealing process is performed, and the active region is separated including a step of selectively removing the amorphous semiconductor on the semiconductor substrate, so that the amorphous semiconductor can be monocrystallized in a self-aligned manner. it can.

Therefore, it is possible to form an element isolation region having an extremely small area without performing a complicated and time-consuming process as in the prior art, which can contribute to mass production of integrated circuits such as ICs and LSIs. It will be possible.

[Brief description of drawings]

FIG. 1 is a manufacturing process explanatory view showing an embodiment of a semiconductor device manufacturing method according to the present invention.

FIG. 2 is a manufacturing process explanatory view showing the embodiment of the method of manufacturing a semiconductor device according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a conventional method for manufacturing a semiconductor device.

FIG. 4 is a schematic cross-sectional view showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

1 Silicon Substrate (Semiconductor Substrate) 2 SiO ₂ Film (Insulating Film) 2a SiO ₂ Film (First Insulating Film) 2b SiO ₂ Film (Second Insulating Film) 3 Opening 3a Opening Sidewall 4 Amorphous Silicon (Amorphous Semiconductor) )

Claims (1)

[Claims] 1. A step of forming (i) a first insulating film on a surface of a semiconductor substrate, and (ii) patterning the first insulating film into a predetermined shape and etching the semiconductor substrate to form an opening. And (iii) forming a second insulating film on the surface of the semiconductor substrate including the opening, and then leaving the second insulating film only on the side wall of the opening by etching, (iv) the semiconductor substrate A method of manufacturing a semiconductor device, comprising the steps of: depositing an amorphous semiconductor on the entire upper surface, performing an annealing treatment, and then selectively removing the amorphous semiconductor on the semiconductor substrate.