JPH113864A - Manufacture of crystalline silicon film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a crystalline silicon film which can take full advantage of LPE(liquid phase epitaxial growing method), by which the cost is reduced by using a low-cost substrate and a crystal of good quality is obtained at the same time. SOLUTION: Silicon is added and melted as a solute to a solvent metal containing at least one of aluminum and gallium. The whole which is kept at 900-1300 deg.C is made into contact with a carbon substrate 20 and a substrate layer 21 containing at least one of aluminum carbide and gallium carbide is formed as a result. Then, the underside of the carbon substrate 20 is cooled so that the temperature may be gradually decreased from the top of the carbon substrate 20 toward its underside, and a crystalline silicon film 22 is formed on the substrate layer 21 on the surface of the carbon substrate 20 within a predetermined range of temperature in the temperature zone between the melting point of the solvent metal and the level at 1300 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a crystalline silicon film based on a liquid phase growth method.

[0002]

2. Description of the Related Art Conventionally, as a method of obtaining a crystalline thin film used as a semiconductor material, conventionally, a solute material is saturated at a high temperature in a solvent having a low melting point, and then the saturated solution is cooled to obtain a supersaturated solute material. Liquid phase growth method (Liquid Phase) to obtain crystalline thin film by depositing as crystals on a substrate
Epitaxy (hereinafter abbreviated as “LPE”) is well known. This LPE is performed using, for example, the following various LPE devices.

[0003] First, the LP of the tipping method (tilt method)
FIG. 4 shows an example of the E apparatus. In this apparatus, a metal solution (hereinafter, referred to as “solvent metal”) 3 serving as a solvent and a raw material 4 serving as a solute are put into a melting tank 2 in a furnace core tube 1 inclined to one side, and the solvent metal 3 is biased. The substrate 5 is mounted in the melting tank 2 on the side opposite to the side where the raw material 4 is diffused and saturated in the solvent metal 3 at a high temperature. Then, the furnace core tube 1 is tilted to the opposite side to move the solute-saturated solvent metal 3 onto the substrate 5 and perform epitaxial growth while lowering the temperature in that state to obtain a crystal film having a predetermined thickness. Again, the furnace core tube 1
Is tilted as before, and the substrate 5 on which the crystal film is formed is taken out. 6 is a thermocouple, 7 is a substrate 5
This is a holding clamp. The inside of the furnace core tube 1 is in an atmosphere of high-purity hydrogen gas or the like.

[0004] In addition, a dipping type (immersion method) LP
FIG. 5 shows an example of the E apparatus. In this apparatus, a platinum crucible 10 containing a solvent metal 3 is placed in a vertical furnace 8, a raw material 4 to be a solute is put therein, melted at a high temperature, and then the substrate 5 is lowered from above. The substrate 5 is immersed in the solvent metal 3 and the temperature is lowered in that state to perform epitaxial growth on the surface of the substrate 5. In addition, 6 is a thermocouple, 11 is an upper heater, and 12 is an alumina tube.

FIG. 6 shows an example of a slide boat type LPE apparatus. In this apparatus, a substrate 5 and a raw material 4 are fitted and held at a predetermined interval on the upper surface of a base plate 13, and a slider 14 holding a solvent metal 3 in a through hole 14a is mounted thereon. After moving the slider 14 to the right so that the material 3 contacts the material 4, the material 4 is diffused and saturated in the solvent metal 3 at a high temperature.
Moves the slider 14 to the left so that the
The temperature is lowered to perform epitaxial growth on the surface of the substrate 5.

[0006] Since the above-mentioned LPE is a crystal growth from a quasi-equilibrium state between a solid phase and a liquid phase, a crystal with high purity and few defects and high integrity can be obtained. This is a major advantage of LPE that other methods do not have. For this reason, LPE is considered promising as a method for producing a crystalline silicon film used as a material for semiconductors.

[0007]

However, in the conventional LPE, when a material different from silicon, such as carbon or stainless steel, is used for the substrate when forming a crystalline silicon film, the lattice constant of silicon differs from that of the substrate. Crystal nuclei are hardly generated, and crystal growth hardly occurs, or even if crystals are generated to some extent, the growth becomes uneven island growth, or the adhesion of the crystal to the substrate is weak, and the crystal peels off immediately. It is known that such problems as frequent occur. Therefore, in order to obtain a crystalline silicon film by LPE, an expensive silicon substrate is used, or a crystalline silicon intermediate layer is formed on an inexpensive substrate using a vapor phase growth method or the like, and then crystal growth by LPE is started. Uneconomical methods are employed, and cost reduction is an important issue.

[0008] The present invention has been made in view of such circumstances, and the use of an inexpensive heterogeneous substrate reduces the cost of the LPE and obtains a high-quality crystal.
It is an object of the present invention to provide a method for producing a crystalline silicon film that can make the most of the characteristics of PE.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, silicon is added as a solute to a solvent metal containing at least one of aluminum and gallium and melted. The substrate was brought into contact with the carbon substrate while maintaining the temperature at 1300 ° C., and an underlayer containing at least one of aluminum carbide and gallium carbide was formed on the surface of the carbon substrate. A crystalline silicon film is formed on the underlayer on the substrate surface in an arbitrary temperature range from the melting point of the solvent metal to 1300 ° C. while giving a temperature gradient such that the temperature gradually decreases from the front side to the back side. Is formed.

[0010] Further, the invention according to claim 2 of the present invention is characterized in that a solvent metal containing at least one of aluminum and gallium is brought into contact with a carbon substrate while maintaining the temperature at 900 to 1300 ° C without adding a solute. A base layer containing at least one of aluminum carbide and gallium carbide is formed on the surface of the substrate, and then silicon is added and melted as a solute in the solvent metal, and the back side of the carbon substrate is cooled to cool the front side of the substrate. A crystalline silicon film is formed on the underlayer on the substrate surface in an arbitrarily determined temperature range from the melting point of the solvent metal to 1300 ° C. while giving a temperature gradient such that the temperature gradually decreases from the back side to the back side. It is something to do.

Further, the invention according to claim 3 of the present invention provides:
A solvent metal containing at least one of aluminum and gallium is brought into contact with a carbon substrate while maintaining the temperature at 900 to 1300 ° C. without adding a solute, and a surface containing at least one of aluminum carbide and gallium carbide is formed on the surface of the carbon substrate. A ground layer is formed, and then, the carbon substrate on which the underlayer is formed is brought into contact with a solvent metal in which silicon is added and melted as a solute, and the back side of the carbon substrate is cooled from the front side to the back side of the substrate by cooling the back side. The crystalline silicon film is formed on the underlayer on the substrate surface in an arbitrarily determined temperature range from the melting point of the solvent metal to 1300 ° C. while giving a temperature gradient so that the temperature gradually decreases. Things.

The invention according to claim 4 of the present invention provides:
At least the surface layer is composed of alumina, silicon carbide, silicon oxide, tungsten carbide, aluminum carbide, gallium carbide, indium carbide, titanium carbide, zirconia, aluminum nitride, boron nitride, magnesium oxide, silicon monoxide, calcium oxide, sialon, and mullite. Prepare a substrate made of at least one material selected from the group, contact this substrate with a solvent metal in which silicon is added and melted as a solute, and cool the back side of the substrate from the front side of the substrate. A crystalline silicon film is formed on the underlayer on the substrate surface in an arbitrarily determined temperature range from the melting point of the solvent metal to 1300 ° C. while giving a temperature gradient such that the temperature gradually decreases toward the back side. It is like that.

According to a fifth aspect of the present invention, there is provided a semiconductor device according to the fourth aspect of the present invention, wherein alumina, silicon carbide, silicon oxide, tungsten carbide, aluminum carbide, gallium carbide, gallium carbide, Use a substrate with an underlayer formed of at least one material selected from the group consisting of indium, titanium carbide, zirconia, aluminum nitride, boron nitride, magnesium oxide, silicon monoxide, calcium oxide, sialon and mullite. According to a sixth aspect of the present invention, there is provided the substrate according to the fourth aspect, wherein the substrate is alumina, silicon carbide, silicon oxide, tungsten carbide, aluminum carbide, gallium carbide, indium carbide, titanium carbide, zirconia. , Aluminum nitride, hoof nitride , Magnesium oxide, is to use silicon monoxide, calcium oxide, a substrate made of at least one material selected from the group consisting of sialon and mullite.

[0014]

Next, embodiments of the present invention will be described in detail.

[0015] The present invention provides, for example,
Is used to manufacture a crystalline silicon film. That is, first, to the solvent metal conventionally used for LPE,
At least one of aluminum and gallium is contained, and silicon is added and melted as a solute. Next, as shown in FIG. 1, a carbon substrate 20 was prepared, and the surface of the carbon
Contact is made at a high temperature of １1300 ° C. to chemically react carbon on the substrate surface with at least one of aluminum and gallium contained in the solvent metal. Thus, as shown in FIG. 2A, an underlayer 21 made of an aluminum carbide-containing layer, a gallium carbide-containing layer, or an aluminum carbide-gallium carbide mixed-containing layer is formed on the surface of the carbon substrate 20. The carbon substrate 2
For the contact between the surface of No. 0 and the solvent metal, a conventionally known LPE apparatus can be appropriately used.

Next, by cooling the back side of the carbon substrate 20 (the surface opposite to the surface on which the underlayer 21 is formed), as shown in FIG. Crystal silicon is deposited on the surface of the underlayer 21 in a temperature range arbitrarily determined within the temperature range from the melting point of the solvent metal to 1300 ° C. while giving a temperature gradient so that the temperature gradually decreases toward the surface. Is formed. This state is shown in FIG. Thus, the crystalline silicon film 22 can be obtained.

The thus-obtained crystalline silicon film 2
2 is dense and of high quality despite being formed on a different type of substrate such as the carbon substrate 20. Since the crystalline silicon film 22 is firmly bonded to the underlayer 21, the crystalline silicon film 22 does not peel off unlike the related art.

The carbon substrate 20 used in the above-mentioned manufacturing method is preferably made of graphite or glassy carbon. In addition, it is no problem to use a substrate surface of another material such as stainless steel coated with graphite or glassy carbon. The thickness of the carbon substrate 20 is usually preferably set to 0.2 to 2 mm. In the case of a substrate in which the surface of a substrate made of another material is coated with carbon, the above-mentioned coating layer has a thickness of 0.1 mm.
It is preferable to set the thickness to 2 to 2 μm. That is, if the coating layer is less than 0.2 μm, the chemical reaction for forming the underlayer 21 may be insufficient, and if it exceeds 2 μm, cracks may occur in the coating layer due to thermal expansion or contraction. Because there is.

Various low melting point metals such as tin, lead, indium, copper and antimony are used as the solvent metal used in the above-mentioned production method. These may be used alone or in combination of two or more. Among them, tin is particularly preferable because a crystalline silicon film having good electric properties can be obtained, the melting point is as low as 232 ° C., and the cost is low.

As described above, the solvent metal contains at least one of aluminum and gallium.
These chemically react with carbon on the surface of the carbon substrate 20 to form carbides.
Form one. The underlayer 21 has good wettability with the solvent metal in which silicon is melt-mixed, and has an effect of forming a crystalline silicon film 22 that is dense and hard to peel off on its surface. In addition, the thickness of the underlayer 21 is set to 0.
It is preferable to set the thickness to 01 to 1 μm, especially 0.05 to 0.2 μm. That is, if the thickness of the underlayer 21 is less than 0.05 μm, the effect of the underlayer 21 cannot be sufficiently obtained, and if it exceeds 1 μm, cracks may occur in the underlayer 21 due to thermal expansion or contraction. .

The content of at least one of aluminum and gallium contained in the solvent metal is preferably set to 1 to 30% by weight (hereinafter abbreviated as "%") with respect to the entire solvent metal. It is particularly preferable to set it to 25%. If the content is less than 1%, the formed film thickness of the underlayer 21 may not be sufficiently obtained. Conversely, if the content exceeds 30%, the film quality of the silicon film to be subsequently formed may be deteriorated. Because there is.

The amount of silicon to be added to and melted in the solvent metal varies depending on the composition and temperature of the solvent metal, but is usually preferably set to 10 to 30% based on the entire solvent metal. Especially, 10% from the saturation point
It is preferable to set the degree of supersaturation. That is, in a state where silicon is unsaturated, there is a risk that it takes too long to form a crystalline silicon film, and conversely if it is too supersaturated,
This is because it is difficult to control the film thickness or crystal precipitation on a jig or the like may cause trouble.

Further, in the above manufacturing method, when cooling from the back side of the carbon substrate 20 to give a temperature gradient such that the temperature gradually decreases from the front side to the back side of the carbon substrate 20, the temperature gradient is 0.1%. It is preferable to set it to ５０50 ° C./mm, and it is particularly preferable to set it to 2〜１０10 ° C./mm. That is, if the temperature gradient is too slow than the above range, a gap may be formed between the crystals, while if too steep, the film quality may be reduced or the thermal efficiency of the furnace body may be reduced. is there.

Then, the crystalline silicon film 2 formed by the cooling
The film-forming speed of No. 2 also depends on other conditions such as the size of the temperature gradient, the composition of the solvent metal, the amount of molten silicon, and the crystal growth temperature, but is usually preferably from 10 to 200 μm / hour (h). Among them, 80 to 120 μm / h is particularly preferable.

When the crystalline silicon film 22 is formed, in addition to cooling while applying a temperature gradient from the back side of the carbon substrate 20 as described above, the solvent metal and the carbon substrate 20 (including the underlayer 21) are formed. There is no problem if the entire system consisting of is uniformly cooled (so-called “cooling method”). In this case, the film formation temperature is from the melting point of the solvent metal to 1
The temperature is set to an arbitrarily determined temperature range within a temperature range of 300 ° C. Then, the cooling rate is preferably set to 0.5 to 10 ° C./min.

Further, the cooling while applying a temperature gradient from the back side of the carbon substrate 20 and the cooling of the entire system are not performed simultaneously, but, for example, the crystalline silicon film 22 has a certain thickness (for example, 0.01 to 1). .0 μm thickness)
Even when the cooling from the back side of the carbon substrate 20 is stopped at the time when the temperature has reached and the temperature is switched to the cooling of the entire system in an arbitrarily determined temperature range from the melting point of the solvent metal to 1300 ° C. A film 22 can be obtained. That is, the crystalline silicon film 22 that has already grown is used as a seed crystal to continue to grow crystalline silicon. In this case, when tin is used as the solvent metal, a higher-quality crystalline silicon film 22 with less crystal defects can be obtained.

Further, in the above-mentioned manufacturing method, silicon is added and melted as a solute from the beginning to a solvent metal containing at least one of aluminum and gallium.
Without adding the silicon, a solvent metal containing aluminum or the like is brought into contact with the carbon substrate 20 while maintaining the temperature at 900 to 1300 ° C. to form an underlayer 21 on the surface of the carbon substrate 20. Add and melt silicon as a solute in the solvent metal, and in the same procedure as above,
A crystalline silicon film 22 may be formed on the underlayer 21. Even in this case, similarly to the above, a high-quality crystalline silicon film 22 can be manufactured at low cost.

A first solvent metal containing only at least one of aluminum and gallium and a second solvent metal containing only silicon are separately prepared. To form an underlayer 21 on the surface of the carbon substrate 20;
The second solvent metal may be brought into contact with the carbon substrate on which the underlayer is formed, and the crystalline silicon film 22 may be formed on the underlayer 21 in the same procedure as described above. The switching between the first solvent metal and the second solvent metal can be easily performed by using, for example, a slide board type LPE apparatus shown in FIG.

In the above-mentioned manufacturing method, the underlayer 21 is formed according to LPE, but the underlayer 21 need not be formed by the above method. For example, a sputtering method, a vacuum deposition method, an ion plating method, various CVD (Chemical)
A base layer 21 is formed by using a Vapor Deposition method, a sol-gel method, or the like.
There is no problem if the carbon substrate 20 with 1 is used. In this case, as a material for forming the underlayer 21, alumina, silicon carbide, silicon oxide, tungsten carbide, aluminum carbide, gallium carbide, indium carbide, titanium carbide, zirconia, aluminum nitride, boron nitride, magnesium oxide, silicon monoxide ( Si
O), calcium oxide, sialon (SiAlON),
Mullite or the like can be used. These may be used alone or in combination of two or more. According to this method, the above-described underlayer forming step can be omitted. In this case, it is not necessary to use a substrate made of carbon as the substrate, and various types of substrates different from silicon can be used. As such a heterogeneous substrate, various substrates such as quartz and silicon nitride can be used as long as they can withstand high temperatures during liquid phase growth and do not dissolve in a solvent.

Further, as a substrate, alumina, silicon carbide, silicon oxide, tungsten carbide, aluminum carbide, gallium carbide, indium carbide, titanium carbide, zirconia, aluminum nitride, boron nitride, magnesium oxide, silicon monoxide, calcium oxide, sialon , Mullite, etc., the base layer forming step can be omitted completely.

[0031]

As described above, the method for producing a crystalline silicon film according to the present invention is directed to a method of forming a special underlayer on a surface of a substrate made of a material different from silicon, or forming a substrate having a surface made of a special material. To provide a temperature gradient so that the temperature gradually decreases from the front side to the back side of the substrate, thereby growing a high-quality crystalline silicon film with a dense and strong bonding strength by LPE. It is like that. According to the above manufacturing method, unlike the conventional method, it is not necessary to use an expensive silicon substrate, and an inexpensive substrate different from silicon can be used. Therefore, LPE can be performed at low cost, and the cost of the semiconductor can be reduced. be able to. Moreover, despite the use of a substrate of a different material, the crystal is of high quality and does not peel off from the substrate, thus exhibiting excellent characteristics over a long period of time.

Further, since the formed product of the crystalline silicon film obtained by the present invention is a combination of a heterogeneous substrate and a crystalline silicon film formed by LPE, it is necessary to use only high-quality crystals formed by LPE for a semiconductor. The properties of good crystals by LPE are not diminished,
The characteristics of E can be fully utilized.

Next, an embodiment will be described.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a substrate, 0.5 mm × 25 mm × 25 m
m carbon substrate was prepared, and a crystalline silicon film was manufactured thereon according to the above-described procedure under the following conditions. In addition, silicon was added from the beginning to the solvent metal and melted, an underlayer was formed first, and then a crystalline silicon film was formed.

[Conditions] Growth temperature 1000 ° C. Composition of solvent metal Aluminum 10% Tin 90% Amount of molten silicon 11% Pressure 1 atm Temperature gradient 5 ° C./mm Film forming speed 1.6 μm / min

The crystalline silicon film thus obtained has a crystal size of 50 to 100 μm and a thickness of about 70 to 100 μm.
It was 100 μm. Moreover, the grown crystals were grown in close contact with each other, and were high quality crystal films with almost no defects.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a manufacturing process according to an embodiment of the present invention.

FIG. 2A is an explanatory view of a manufacturing process of the above embodiment,
(B) is an explanatory view of a temperature gradient applied to the substrate in the above manufacturing process.

FIG. 3 is an explanatory view of a manufacturing process of the embodiment.

FIG. 4 is an explanatory diagram illustrating an example of an LPE apparatus.

FIG. 5 is an explanatory diagram showing another example of the LPE device.

FIG. 6 is an explanatory diagram showing still another example of the LPE device.

[Explanation of symbols]

 Reference Signs List 20 carbon substrate 21 underlayer 22 crystalline silicon film

Claims (6)

[Claims] 1. A method in which silicon is added as a solute to a solvent metal containing at least one of aluminum and gallium, melted and brought into contact with a carbon substrate while maintaining the temperature at 900 to 1300 ° C., and aluminum carbide and Forming an underlayer containing at least one of gallium carbide, and then cooling the back side of the carbon substrate to give a temperature gradient such that the temperature gradually decreases from the front side to the back side of the substrate; A crystalline silicon film is formed on an underlayer on a substrate surface in an arbitrarily determined temperature range from a melting point of 1300 ° C. to 1300 ° C. 2. A solvent metal containing at least one of aluminum and gallium, 900 to 1 without adding a solute.
The substrate is brought into contact with the carbon substrate while maintaining the temperature at 300 ° C., and an underlayer containing at least one of aluminum carbide and gallium carbide is formed on the surface of the carbon substrate. Then, silicon is added and melted as a solute in the solvent metal. Then, while cooling the back side of the carbon substrate to give a temperature gradient such that the temperature gradually decreases from the front side to the back side of the substrate, the melting point of the solvent metal to 1300 ° C.
Forming a crystalline silicon film on an underlayer on a substrate surface within an arbitrarily determined temperature range within the above temperature range. 3. A method according to claim 1, wherein a solvent metal containing at least one of aluminum and gallium is added without adding a solute.
In contact with the carbon substrate in a state maintained at 300 ° C., on the surface of the carbon substrate, forming an underlayer containing at least one of aluminum carbide and gallium carbide, then, on the carbon substrate on which the underlayer is formed, As a solute, silicon is added and brought into contact with a molten solvent metal, and by cooling the back side of the carbon substrate, a temperature gradient is provided so that the temperature gradually decreases from the front side to the back side of the substrate. A method for producing a crystalline silicon film, characterized in that a crystalline silicon film is formed on an underlayer on a substrate surface in an arbitrarily determined temperature range of up to 1300 ° C. 4. At least a surface layer is made of alumina, silicon carbide, silicon oxide, tungsten carbide, aluminum carbide, gallium carbide, indium carbide, titanium carbide, zirconia, aluminum nitride, boron nitride, magnesium oxide, silicon monoxide, calcium oxide, Preparing a substrate formed of at least one material selected from the group consisting of sialon and mullite, contacting this substrate with a solvent metal in which silicon is added and melted as a solute, and cooling the back side of the substrate The crystal is formed on the underlayer on the surface of the substrate in an arbitrarily determined temperature range from the melting point of the solvent metal to 1300 ° C. while giving a temperature gradient so that the temperature gradually decreases from the front side to the back side of the substrate. A method for producing a crystalline silicon film, wherein a silicon film is formed. 5. The method according to claim 5, wherein the substrate is a carbon substrate having alumina, silicon carbide, silicon oxide, tungsten carbide, aluminum carbide, gallium carbide, indium carbide, titanium carbide, zirconia, aluminum nitride, boron nitride, magnesium oxide, and monoxide. 5. The method for producing a crystalline silicon film according to claim 4, wherein the substrate is a substrate with an underlayer on which an underlayer made of at least one material selected from the group consisting of silicon, calcium oxide, sialon and mullite is formed. 6. The method according to claim 1, wherein the substrate is alumina, silicon carbide,
Silicon oxide, tungsten carbide, aluminum carbide,
5. A substrate comprising at least one material selected from the group consisting of gallium carbide, indium carbide, titanium carbide, zirconia, aluminum nitride, boron nitride, magnesium oxide, silicon monoxide, calcium oxide, sialon and mullite. Of crystalline silicon film.