JPH05326683A - Manufacutre of soi substrate - Google Patents

Abstract

PURPOSE:To provide the manufacture of an SOI substrate with a large area, which can easily and accurately form a thin semiconductor crystal layer on a silicon substrate through an insulating film, and a semiconductor device excellent in radiation resistance property, consisting of such SOI substrate. CONSTITUTION:A semiconductor crystal layer (cubic silicon carbide layer 3) is made, which is separated completely from a silicon substrate by an insulating film (silicon dioxide film 4) by sticking a second silicon substrate 5 and removing the silicon layer 6 of the first silicon substrate 1 after epitaxially growing cubic silicon carbide on one main surface of a first silicon substrate 1, and forming a silicon dioxide film 4 on this cubic silicon layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an SOI substrate manufacturing method. More specifically, S in which a semiconductor crystal layer made of silicon carbide is formed on an insulating film formed on a semiconductor substrate
The present invention relates to a method for manufacturing an OI substrate and a semiconductor device using the substrate.

In the present specification, SOI is used as a term meaning a semiconductor crystal layer formed on an insulating film.

[0003]

2. Description of the Related Art Conventionally, an SOI substrate has been expected as an element excellent in radiation resistance, and various methods for forming a semiconductor crystal layer on an insulating substrate have been studied. For example, a method of manufacturing an SOI substrate by using two silicon substrates is known. In this manufacturing method, an oxide film is formed on the surface of one of the two silicon substrates, and then both silicon substrates are bonded via this oxide film, and one of the silicon layers is thinned on the oxide film. The polishing is performed so that the layer remains. However, if the silicon layer is left in a uniform and thin layer,
It is extremely difficult to control the polishing.

In order to improve the drawbacks of the method of polishing after laminating, there has been proposed a method of manufacturing an SOI substrate in which a polishing restraining portion also made of silicon dioxide is formed integrally with an insulating film of silicon dioxide (Japanese Patent Laid-Open No. HEI 2-). (See Japanese Patent No. 5546).

That is, according to this manufacturing method, as shown in FIG. 2, a predetermined groove 53 is formed on one surface 52 of the first silicon substrate 51, a silicon dioxide film is formed in the inside of the groove, and a poly-silicon resin is used as a filler. Silicon 54 is embedded, a silicon dioxide film 55 is formed on the surface including the inner surface of the groove, and then a second silicon substrate 56 is attached via the silicon dioxide film 55. If silicon dioxide is polished from the side of the first silicon substrate 51 thereafter, the polishing rate of silicon dioxide is lower than that of silicon. Therefore, as shown in FIG.
The polishing is stopped when 57 is exposed.
In this way, the silicon dioxide film 57 inside the groove functions as the polishing inhibiting portion. As a result, the silicon 58 surrounded by the preformed silicon dioxide region (inside the groove) 57 is formed on the silicon dioxide film 55 to a certain thickness.

[0006]

However, in the above conventional method for manufacturing an SOI substrate, the polishing inhibiting portion (so-called stopper) when polishing the silicon layer is integrally formed with the insulating film for the purpose of facilitating the formation thereof. Formed from,
In a sense, it has a frame shape. Therefore, if the spacing between the polishing inhibiting portions is wide, the silicon layer in the middle portion is polished to form recesses, and it is difficult to obtain a flat SOI substrate. On the other hand, if the spacing is narrowed, only the semiconductor crystal layer in a small island region is obtained. There is a problem that you can not. Furthermore, since neither silicon nor silicon dioxide is a material having excellent chemical resistance, further caution is required when polishing with an amine-based aqueous solution. In addition, since the silicon layer constituting the semiconductor crystal layer of the SOI substrate is divided into the frame-shaped polishing inhibiting portion made of silicon dioxide, only the portion excluding the polishing inhibiting portion has to be used, which is small. There is a problem that it becomes a substrate.

The present invention has been made in order to solve the above problem, and forms a large-area SOI substrate in which the semiconductor crystal layer of the SOI substrate has no breaks at all, and the semiconductor crystal layer of the SOI substrate is formed. A method of manufacturing an SOI substrate in which polishing of a silicon layer can be easily controlled by adopting silicon carbide having significantly higher chemical resistance than silicon and extremely high hardness, and a semiconductor device using such an SOI substrate are provided. The purpose is to provide.

Another object of the present invention is to provide a method of manufacturing an SOI substrate and a semiconductor device having further improved radiation resistance as compared with a conventional SOI substrate.

[0009]

A method of manufacturing an SOI substrate according to the present invention comprises a step of preparing a first silicon substrate and a second silicon substrate, and silicon carbide on one main surface of the first silicon substrate. A step of epitaxially growing, a step of forming an insulating film on at least one of the main surface of the grown silicon carbide and one main surface of the second silicon substrate, and a step of interposing the insulating film. From the step of bonding the first silicon substrate and the second silicon substrate, and the step of polishing the bonded substrate from the other main surface side of the first silicon substrate to expose the silicon carbide on the entire surface. It is characterized by becoming.

The step of exposing the silicon carbide in the above-mentioned manufacturing method comprises the step of polishing from the other main surface side of the first silicon substrate, and the step of removing the remaining silicon layer by the etching solution after the step. It can also be configured.

The semiconductor device of the present invention is characterized in that the SOI substrate manufactured by the above manufacturing method is used.

[0012]

According to the present invention, when the silicon layer of the intermediate product integrally bonded by the heat treatment is polished with, for example, an amine-based aqueous solution containing colloidal silica, the polishing and chemical resistance of silicon carbide can be improved. Due to its extremely high polishing rate, it is significantly lower than that of a silicon layer, so polishing stops when silicon carbide is exposed on the polished surface, and a uniform thickness when formed almost at the beginning. The silicon carbide layer remains as it is as a semiconductor crystal layer of the SOI substrate. As described above, a substrate having an SOI structure having a large area and a uniform and extremely thin semiconductor crystal layer can be manufactured very easily. Moreover, by adopting silicon carbide for the semiconductor crystal layer, a semiconductor device excellent in radiation resistance and mechanical strength can be obtained.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for manufacturing an SOI substrate of the present invention (hereinafter simply referred to as a manufacturing method) will be described with reference to the accompanying drawings. FIG. 1 is a process drawing showing an embodiment of the manufacturing method of the present invention.

First, as shown as step a in FIG.
Cubic silicon carbide (3C-SiC) 3 is epitaxially grown on one main surface 2 of the first silicon substrate 1.
Specifically, the main surface 2 of the first silicon substrate 1 heated to about 1350 ° C. is charged with hydrogen (H ₂ ) using disilane (Si ₂ H ₆ ) and acetylene (C ₂ H ₂ ) as source gases. By introducing a mixed gas using as a carrier gas to cause a gas phase reaction, a single crystal of cubic silicon carbide 3 is epitaxially grown using the silicon crystal of the silicon substrate as a seed. The reaction is continued for about 25 minutes and grown to a thickness of about 5000 Angstroms. The thickness of the grown cubic silicon carbide layer 3 is uniform over the entire main surface 2.

Then, as shown as step b in FIG. 1, a silicon oxide film as an insulating film is formed on the surface of the cubic silicon carbide layer 3. Specifically, TEOS (S
i (OC ₂ H ₅ ) ₄ ) gas and oxygen gas are introduced to about 400
A silicon dioxide film 4 having a thickness of about 5000 angstroms is formed by a CVD method in which vapor phase growth is performed at ℃. The silicon dioxide film 4 has a uniform thickness over the entire surface of the cubic silicon carbide layer 3. Although the oxidation rate of silicon carbide is about half that of silicon, it should be formed by heat treatment at 900-1100 ° C for about 2 hours by the same thermal oxidation method used for silicon. You can also It should be noted that the present invention is not limited to forming the insulating film only on the first silicon substrate 1 side as described above, and may be formed, for example, only on the surface of the second silicon substrate 5 described later or on both substrates 1. Both surfaces 5 may be formed.

Next, as shown as step c in FIG. 1, a second silicon substrate 5 is separately prepared and attached to the silicon dioxide film 4 side of the first silicon substrate 1.
Specifically, using a known silanol bonding method or the like, the second
While the surface of the silicon substrate 5 is in pressure contact with the surface of the silicon dioxide film 4 of the first silicon substrate, heat treatment is performed at a temperature of 800 to 1200 ° C. for about 30 minutes to perform pressure bonding. In addition to the silanol bonding method, the first and second substrates 1 and 5 may be attached by a method of applying a pulse voltage of about ± 300 V at about 1000 ° C. for about 5 minutes.

The insulating film is not limited to the above silicon dioxide film, and a silicon nitride film can be used, for example, but a silicon dioxide film is preferable from the viewpoint of thermal expansion damage.

Finally, as shown as step d in FIG. 1, only the silicon layer 6 is removed by polishing from the other main surface side of the first silicon substrate 1 of the bonded and integrated substrate. The surface of the cubic silicon carbide layer 3 is exposed.
In this embodiment, as the abrasive, an amine aqueous solution mixed with colloidal silica is used. Compared with silicon and silicon dioxide, silicon carbide has remarkably excellent chemical resistance, and since its hardness is much higher than that of diamond, the polishing rate is significantly smaller than those of the above. Therefore, when the silicon layer 6 of the first silicon substrate 1 is polished, the polishing is accurately and automatically stopped when the cubic silicon carbide layer 3 is exposed.
In this way, the SOI substrate in which the semiconductor crystal layer made of the cubic silicon carbide layer 3 is formed on the silicon substrate (the second silicon substrate 5 in the step d of FIG. 1) via the silicon dioxide film 4 serving as an insulating film. Is created.

In the present invention, the step d is not limited to the step of removing the silicon layer only by polishing. For example, the silicon layer is removed by polishing to some extent, and then potassium hydroxide (KOH) or the like is used. ,
A step of etching away the remaining silicon with a solution capable of etching the silicon may be substituted. This can be achieved by adopting cubic silicon carbide, which has extremely excellent chemical resistance, as the semiconductor crystal of the SOI substrate as described above.

Further, although an amine-based aqueous solution mixed with colloidal silica was used as the abrasive in the above-mentioned examples, the present invention is not limited to such an abrasive, and for example, an Al ₂ O ₃ -based abrasive is used. A material or the like may be used.

The semiconductor crystal layer of the SOI substrate of the present invention is not particularly limited to cubic silicon carbide, but hexagonal or polycrystalline silicon carbide may be used, for example.
Cubic silicon carbide is preferable because it can be formed at a temperature of about 1350 ° C. and the crystallinity of the silicon layer can be maintained at such a temperature.

A semiconductor device having an integrated circuit is obtained by forming a semiconductor circuit on the SOI substrate manufactured by the above manufacturing method by a usual process. Such a semiconductor device uses silicon carbide, which has excellent radiation resistance, as S
Since it is used as the semiconductor crystal layer of the OI substrate, the
By adopting the OI substrate structure, the radiation resistance achieved can be further improved to meet the needs of users.

[0023]

According to the present invention, a silicon carbide crystal layer is epitaxially grown on a silicon substrate and an SOI substrate is formed by using a bonding method. Therefore, as compared with a conventional method for manufacturing an SOI substrate, It is much easier to form a thin semiconductor crystal layer on the insulating film with an accurate thickness, and a large area SOI structure can be formed. Moreover, it is possible to manufacture a semiconductor device having significantly improved radiation resistance as compared with the conventional SOI substrate.

[Brief description of drawings]

FIG. 1 is a process drawing showing an embodiment of a manufacturing method of the present invention.

FIG. 2 is an explanatory diagram showing a step in an example of a conventional manufacturing method.

FIG. 3 is an explanatory view showing another process in the conventional manufacturing method of FIG.

[Explanation of symbols]

 1 First Silicon Substrate 2 Main Surface 3 Cubic Silicon Carbide Layer 4 Silicon Dioxide Film 5 Second Silicon Substrate 6 Silicon Layer

Claims (5)

[Claims] 1. A step of (a) preparing a first silicon substrate and a second silicon substrate, (b) a step of epitaxially growing silicon carbide on one main surface of the first silicon substrate, and (c) ) A step of forming an insulating film on at least one of the main surface of the grown silicon carbide and one main surface of the second silicon substrate, and (d) a first step for interposing the insulating film. Bonding the silicon substrate and the second silicon substrate, and (e) polishing the bonded substrate from the other main surface side of the first silicon substrate,
S exposing the silicon carbide to the entire surface
Manufacturing method of OI substrate. 2. The step of exposing the silicon carbide,
A step of polishing from the other main surface side of the first silicon substrate,
The method according to claim 1, comprising a step of removing the remaining silicon layer with an etching solution after the step. 3. The method according to claim 1, wherein the silicon carbide is cubic silicon carbide. 4. The method according to claim 1, wherein the insulating film is a silicon dioxide film. 5. The S produced by the manufacturing method according to claim 1.
A semiconductor device using an OI substrate.