JP2021180225A - Manufacturing method of semiconductor substrate, manufacturing method of soi wafer and soi wafer - Google Patents

Abstract

To provide a manufacturing method of a semiconductor substrate which can form an SiC single crystal film that has high crystallinity and is thick in film thickness with a low defect on a silicon single crystal substrate.SOLUTION: A manufacturing method of a semiconductor substrate having an SiC single crystal film on the surface comprises: a step of adhering carbon to the surface of the silicon single crystal substrate; a step of forming an SiC single crystal base film by carbonizing the surface of the silicon single crystal substrate adhered with the carbon; a step of forming an amorphous silicon film on the SiC single crystal base film; and a step of making the SiC single crystal base film a seed crystal and making the amorphous silicon film the SiC single crystal film with the solid phase growth.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a semiconductor substrate having a SiC single crystal film on the surface of a silicon single crystal substrate, and an SOI wafer having a silicon single crystal substrate and a SiC single crystal film.

The SiC single crystal substrate is a material capable of realizing a semiconductor device having low loss, excellent high frequency characteristics, high withstand voltage, high thermal conductivity, and high breakdown electric field as compared with the Si single crystal substrate. FIG. 13 shows the physical characteristics of the main semiconductor materials.

In Patent Document 1, the SOI substrate is heated in a carbide-based gas atmosphere to transform the Si layer on the surface into a single crystal SiC film, and the single crystal SiC film is epitaxially grown as a seed layer to grow the single crystal SiC substrate. (However, it is disclosed that the base substrate is an SOI substrate). _{Further, in Patent Document 2, it is possible to form a silicon oxide film (SiO 2} ) that functions as an embedded oxide film on the entire surface of a single crystal silicon substrate that functions as a support substrate, and to form a SiC film on the silicon oxide film (SiO 2) that functions as an embedded oxide film. It has been disclosed. Further, Patent Document 3 discloses that a semiconductor substrate having a single crystal SiC film on the surface is used as a support substrate for the compound semiconductor substrate.

Japanese Unexamined Patent Publication No. 2007-123675 Japanese Unexamined Patent Publication No. 2008-41830 Japanese Unexamined Patent Publication No. 2014-76925

Patent Document 1 discloses a method of forming a single crystal SiC layer by epitaxially growing a single crystal SiC film as a seed layer. In the case of this manufacturing process, the lattice constant mismatch rate of Si (0.543 nm) / 3C-SiC (0.453 nm) in the first layer is 20%, and a large amount of defects are induced to alleviate this. When epitaxial is grown on a seed in which a large amount of defects are generated in this way, there is a problem that epi-defects due to defects on the seed are generated. Although it is possible to increase the thickness of the SiC single crystal film by epitaxial growth, it was not possible to obtain a SiC single crystal film having excellent crystallinity with low defects.

In Patent Document 2, a silicon oxide film (SiO ₂ ) that functions as an embedded oxide film and a SiC film itself or a SiC-containing layer that functions as a lattice strain forming layer in which SiC bonds are mixed are formed on the silicon oxide film (SiO 2). Although the SOI substrate is disclosed, the method for forming the SiC single crystal layer is not described.

Patent Document 3 discloses a method of forming a GaN film using a substrate on which a SiC single crystal thin film is formed on a silicon substrate as a support substrate, but the SiC single crystal thin film is not used as a buffer layer. Further, the defect of the SiC single crystal layer itself and the method of forming the SiC single crystal layer are not mentioned.

Further, in SOI power ICs for high withstand voltage applications exceeding 600 V, a thick BOX layer of several μm is required. Such SOI power devices and RF devices have excellent dielectric strength characteristics, but generate a large amount of heat from the devices, so that it is required to dissipate heat to the base substrate side as well. However, since the thick SiO ₂ film has poor heat conduction and heat is trapped, conventionally, when designing a device, a metal electrode is provided on the device surface side on the SOI layer side, and a water-cooled heat sink or the like is set on the upper side. Was there. In order to obtain such a complicated structure, it is necessary to go through a complicated process, which is disadvantageous in terms of cost and productivity.

As described above, in the silicon single crystal substrate having a SiC single crystal film, it has been required to manufacture a silicon single crystal substrate having a thick SiC single crystal film having low defects and high crystallinity. Further, there has been a demand for an SOI wafer having a simple structure, capable of suppressing leakage current to the maximum, and having high heat dissipation to the base substrate side.

The present invention has been made to solve the above problems, and is a method for manufacturing a semiconductor substrate capable of forming a thick SiC single crystal film having low defects and high crystallinity on a silicon single crystal substrate, and a method for manufacturing the semiconductor substrate. , It is an object of the present invention to provide an SOI wafer provided with a silicon single crystal substrate having a SiC single crystal film.

The present invention has been made to achieve the above object, and is a method for manufacturing a semiconductor substrate having a SiC single crystal film on the surface, which comprises a step of adhering carbon to the surface of the silicon single crystal substrate and the carbon. A step of forming a SiC single crystal base film by carbonizing the surface of the silicon single crystal substrate to which the above is adhered, a step of forming an amorphous silicon film on the SiC single crystal base film, and a step of forming the SiC single crystal base film. Provided is a method for manufacturing a semiconductor substrate, which comprises a step of converting the amorphous silicon film into a SiC single crystal film by solid-phase growth as a seed crystal.

According to such a method for manufacturing a semiconductor substrate, an amorphous silicon film is grown on a SiC single crystal base film, and a SiC single crystal film is grown by carbon injection and solid-phase growth by RTA. Defects on the ground film are not introduced into the SiC single crystal film that has grown in solid phase directly above, and a semiconductor substrate having a low defect, high crystallinity, and a thick SiC single crystal film is formed on the silicon single crystal substrate. Can be manufactured.

At this time, in the step of adhering carbon to the surface of the silicon single crystal substrate, the silicon single crystal substrate can be subjected to RTA treatment at 800 ° C. or lower in a carbon-containing atmosphere as a method for manufacturing a semiconductor substrate.

As a result, carbon can be adhered more uniformly to the surface of the silicon single crystal substrate in a more sufficient amount, so that a SiC single crystal base film having higher crystallinity can be formed in a subsequent step, and solid phase growth can be formed on the SiC single crystal base film. The crystallinity of the SiC single crystal film formed in 1 can be made higher.

At this time, in the step of forming the SiC single crystal base film, the silicon single crystal substrate is subjected to RTA treatment at 1150 ° C. to 1300 ° C. in a carbon-containing atmosphere to form a SiC single crystal base film having a thickness of 7 nm or less. It can be used as a method for manufacturing a semiconductor substrate.

As a result, a SiC single crystal base film having higher crystallinity can be obtained, and the crystallinity of the SiC single crystal film formed on the SiC single crystal base film by solid phase growth can be further increased.

At this time, in the step of forming the amorphous silicon film, an amorphous silicon film having a thickness of 3 times or less the thickness of the SiC single crystal undercoat is placed on the SiC single crystal undercoat at a growth temperature of 300 to 600 ° C. It can be used as a method for manufacturing a semiconductor substrate for vapor phase growth.

If the thickness of the amorphous silicon film is within such a range, it is possible to obtain a silicon film that maintains an amorphous form more stably, and the crystallinity when a SiC single crystal film is formed by solid phase growth is stabilized. Can be higher.

At this time, in the step of converting the amorphous silicon film into a SiC single crystal film by the solid phase growth, it is possible to use a method for manufacturing a semiconductor substrate in which the silicon single crystal substrate is RTA-treated at 1150 ° C. to 1300 ° C. in a carbon-containing atmosphere. can.

This makes it possible to surely form a SiC single crystal film having higher crystallinity.

At this time, it is possible to use a method for manufacturing a semiconductor substrate in which the step of forming the amorphous silicon film and the step of forming the amorphous silicon film into a SiC single crystal film are repeated two or more times.

This makes it possible to form a thick SiC single crystal film with low defects and high crystallinity.

At this time, it is possible to use a method for manufacturing a semiconductor substrate in which the SiC single crystal film is formed thicker than 15 nm.

According to the method for manufacturing a semiconductor substrate according to the present invention, it is particularly suitable for forming a semiconductor substrate having such a thickness, and a thick SiC single crystal film having low defects and high crystallinity can be obtained.

At this time, the method for manufacturing a semiconductor substrate in which the SiC single crystal base film and the SiC single crystal film are 3C-SiC can be used.

According to the present invention, such a semiconductor substrate can be suitably manufactured.

At this time, a silicon single crystal substrate having a SiC single crystal film manufactured by the above-mentioned method for manufacturing a semiconductor substrate can be used as a base substrate for an SOI wafer, and the method for manufacturing an SOI wafer can be used.

As a result, it is possible to manufacture an SOI wafer in which the leakage current is suppressed and the heat dissipation to the base substrate side is high.

At this time, a silicon single crystal substrate having a SiC single crystal film manufactured by the above semiconductor substrate manufacturing method can be used as a starting substrate, and a semiconductor substrate manufacturing method for forming a compound semiconductor film on the SiC single crystal film can be used. can.

This makes it possible to form a compound semiconductor film by using an inexpensive silicon single crystal substrate and allowing a highly crystalline SiC single crystal film to function as a buffer layer.

The present invention also has a support substrate, an insulating layer on the support substrate, and an SOI layer on the insulating layer. The support substrate is a silicon single crystal substrate, and the insulating layer is a single 3C-SiC. Provided is an SOI wafer made of a crystal film.

According to such an SOI wafer, the leakage current is suppressed and the SOI wafer has high heat dissipation to the base substrate side.

As described above, according to the method for manufacturing a semiconductor substrate of the present invention, an amorphous silicon film is grown on a SiC single crystal base film, and a SiC single crystal film is grown by carbon injection and solid phase growth by RTA. , Defects on the SiC single crystal base film are not introduced into the SiC single crystal film grown in solid phase directly above, and a thick SiC single crystal film with low defects and high crystallinity is provided on the silicon single crystal substrate. It becomes possible to manufacture a semiconductor substrate. Further, according to the SOI wafer of the present invention, the SOI wafer is one in which the leakage current is suppressed and the heat dissipation to the base substrate side is high.

The flow diagram and the conceptual diagram of the manufacturing method of the semiconductor substrate which concerns on this invention are shown. The semiconductor substrate obtained by the manufacturing method of the semiconductor substrate which concerns on this invention is shown. The SOI wafer according to this invention is shown. The flow chart of Example 1 is shown. The cross-sectional TEM observation result of the 3C-SiC single crystal film obtained in Example 1 is shown. The crystallinity evaluation result of the 3C-SiC single crystal film obtained in Example 1 is shown. The flow chart of Example 2 is shown. The cross-sectional TEM observation result of the 3C-SiC single crystal film obtained in Example 2 is shown. The crystallinity evaluation result of the 3C-SiC single crystal film obtained in Example 2 is shown. The flow chart of the comparative example is shown. The cross-sectional TEM observation result of the 3C-SiC single crystal film obtained in the comparative example is shown. The crystallinity evaluation result of the 3C-SiC single crystal film obtained in the comparative example is shown. Shows the physical characteristics of the main semiconductor materials.

Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

As described above, a method for manufacturing a semiconductor substrate that has low defects and high crystallinity and forms a thick SiC single crystal film on a silicon single crystal substrate, and a silicon single crystal substrate having a SiC single crystal film are provided. SOI wafers have been sought.

As a result of diligent studies on the above-mentioned problems, the present inventors have described a process of adhering carbon to the surface of a silicon single crystal substrate, which is a method of manufacturing a semiconductor substrate having a SiC single crystal film on the surface, and the carbon. A step of carbonizing the surface of the attached silicon single crystal substrate to form a SiC single crystal base film, a step of forming an amorphous silicon film on the SiC single crystal base film, and a step of forming the SiC single crystal base film as seeds. By a method for manufacturing a semiconductor substrate including a step of converting the amorphous silicon film into a SiC single crystal film by solid-phase growth as a crystal, a thick SiC single crystal having low defects and high crystallinity can be obtained on the silicon single crystal substrate. We have found that it is possible to manufacture a semiconductor substrate provided with a film, and completed the present invention.

Further, the present inventors have a support substrate, an insulating layer on the support substrate, and an SOI layer on the insulating layer, the support substrate is a silicon single crystal substrate, and the insulating layer is 3C-. We have found that an SOI wafer made of a SiC single crystal film suppresses leakage current and has high heat dissipation to the base substrate side, and completed the present invention.

Hereinafter, a method for manufacturing a semiconductor substrate and application to various semiconductor substrates such as SOI wafers according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3.

The present inventors can reduce the leakage current when applied to an SOI wafer if the semiconductor substrate has a low defect, high quality, and a thick film (for example, more than 15 nm) SiC single crystal film. We focused on the fact that the thermal conductivity can be improved and that it can function as a buffer layer of a compound semiconductor substrate. It is difficult to form a thick SiC single crystal film by the method of forming a SiC single crystal film by carbonizing the surface of a silicon single crystal substrate. In order to solve such problems, we conducted a diligent investigation and found that carbon was adhered to the surface of the silicon single crystal substrate, and a thin SiC single crystal base film was formed by RTA treatment in a carbon-containing atmosphere, and the film was thick. By growing the amorphous silicon film in a gas phase at a low temperature and then performing RTA treatment, the SiC single crystal base film is used as a seed crystal, and the amorphous silicon changes to a SiC single crystal by solid phase growth, and the crystallinity is higher than before. It has been found that a thick SiC single crystal film can be obtained. Furthermore, by repeating the process of vapor-phase growing thick amorphous silicon on the surface of the SiC single crystal film and then changing it to a SiC single crystal by solid-phase growth, it is thicker than 15 nm, which was not possible in the past. We have found that a high-quality SiC single crystal film can be formed, and completed the present invention.

(Semiconductor substrate)
FIG. 2 shows a semiconductor substrate obtained by the method for manufacturing a semiconductor substrate according to the present invention. As shown in FIG. 2, the semiconductor substrate 10 has a SiC single crystal base film 3 and a SiC single crystal film 5 on a silicon single crystal substrate 1. The type of the silicon single crystal substrate 1 used is not particularly limited. Further, the SiC single crystal base film 3 and the SiC single crystal film 5 can be 3C-SiC. Such a SiC single crystal film 5 has lower defects, higher crystallinity, and a thicker film than the conventional SiC single crystal film. Further, such a semiconductor substrate 10 can be applied as follows.

(SOI wafer)
FIG. 3 shows an SOI wafer according to the present invention. As shown in FIG. 3, the SOI wafer 20 according to the present invention uses the semiconductor substrate 10 as the base substrate 14, and the support substrate 11 and the insulating layer 12 are silicon single crystals in the semiconductor substrate 10, respectively. It corresponds to the substrate 1, the SiC single crystal base film 3, and the SiC single crystal film 5. The SOI layer 13 is provided on the SiC single crystal base film 3 and the SiC single crystal film 5 used as the insulating layer 12.

3C-SiC has a thermal conductivity (W / cm · K) higher than that of _{SiO 2.}
Since 3C-SiC / SiO ₂ = 4.9 / 1.38 = about 3.5 times higher, if 3C-SiC is used as the insulating layer as in the SOI wafer according to the present invention, heat is dissipated to the base substrate side. It will be excellent in terms of heat dissipation. Unlike the conventional SOI wafer provided with a BOX layer, it is not necessary to provide a metal electrode on the device surface side on the SOI layer side and set a water-cooled heat sink or the like on the upper side thereof.

(Semiconductor substrate forming a compound semiconductor film)
It is also possible to use the semiconductor substrate 10 shown in FIG. 2 and form a semiconductor substrate in which a compound semiconductor film such as a III-V semiconductor is provided on the semiconductor substrate 10. Since the semiconductor substrate manufactured by the method for manufacturing a semiconductor substrate according to the present invention can be a semiconductor substrate having a highly crystalline and thick SiC single crystal film, the SiC single crystal film can function as a buffer layer. Will be.

(Manufacturing method of semiconductor substrate)
Next, a method for manufacturing a semiconductor substrate according to the present invention will be described. FIG. 1 is a flow chart and a conceptual diagram showing an outline of a method for manufacturing a semiconductor substrate according to the present invention. Hereinafter, each step will be described.

First, the silicon single crystal substrate 1 is prepared ((a) in FIG. 1). The silicon single crystal substrate 1 used is not particularly limited. For example, at present, a silicon single crystal substrate in the V region is used as a silicon substrate for manufacturing a GaN substrate, but such a silicon single crystal substrate can be used. A silicon single crystal substrate having a predetermined plane orientation such as (100) or (111) can be used. Hereinafter, an example of forming a 3C-SiC single crystal as a SiC single crystal will be described.

First, as shown in FIG. 1B, a step of adhering carbon 2 to the surface of the silicon single crystal substrate 1 is performed. By performing this step, carbon 2 can be uniformly and sufficiently adhered to the surface of the silicon single crystal substrate 1, and then the surface of the silicon single crystal substrate 1 is carbonized under the SiC single crystal. In the step of forming the ground film, a SiC single crystal base film that can function as a seed crystal can be formed. In this step, it is preferable to RTA-treat the silicon single crystal substrate 1 in a carbon-containing atmosphere. As the carbon-containing atmosphere, for example, _{a carbon-containing gas such as CH 4} , C ₂ H ₄ , C ₃ H ₈ is used, and a mixed atmosphere of _{H 2} or Ar + H ₂ is used so that the carbon concentration becomes 1% or more. Can be done. The RTA treatment is preferably performed at a relatively low temperature of 800 ° C. or lower, and more preferably 700 to 800 ° C. for 20 to 40 seconds.

Next, as shown in FIG. 1 (c), a step of carbonizing the surface of the silicon single crystal substrate 1 to which carbon 2 is attached to form 3C-SiC to form a SiC single crystal base film 3 is performed. In this step, it is preferable to form a SiC single crystal base film 3 having a thickness of 7 nm or less by subjecting the silicon single crystal substrate to RTA treatment at 1150 ° C. to 1300 ° C. in a carbon-containing atmosphere. As the carbon-containing atmosphere, for example, CH ₄ , C ₂ H ₄ , C ₃ H _8, or the like can be used, and a mixed atmosphere of _{H 2} or Ar + H ₂ can be used so that the carbon concentration is 1% or more. The RTA treatment is more preferably carried out, for example, at 1150 ° C. or higher and 1300 ° C. or lower for 10 to 100 seconds. By such RTA treatment, Si sublimated from the silicon single crystal substrate reacts with carbon (C) adhering to the surface and carbon (C) in the atmosphere, and the surface of the silicon single crystal substrate 1 is about 7 nm or less. A thin SiC single crystal base film 3 can be formed.

In the case of the sublimation method, if the Si supply becomes insufficient, the growth will stop. When the RTA temperature is 1300 ° C., the SiC single crystal grows up to about 7 nm. When the RTA temperature is less than 1150 ° C., the thickness of the SiC single crystal is less than 2 nm. In order to make the SiC single crystal base film 3 function more effectively as a seed crystal in a later step, it is preferably about 2 nm to 7 nm.

Next, as shown in FIG. 1 (d), a step of forming the amorphous silicon film 4 on the SiC single crystal base film 3 is performed. In this step, a CVD device is used to supply a raw material gas for a silane gas (for example, monosilane, trichlorosilane, etc.), and amorphous silicon can be vapor-deposited at 300 ° C to 600 ° C. The thickness of the amorphous silicon film 4 formed at this time is preferably 3 times or less the thickness of the SiC single crystal base film 3. With such a thickness, the amorphous silicon film 4 can be stably formed, and a SiC single crystal having high crystallinity can be stably formed by the subsequent RTA treatment.

Next, as shown in FIG. 1 (e), the amorphous silicon film 4 is converted into 3C-SiC by solid phase growth to form a SiC single crystal film 5. In this step, it is preferable to RTA-treat the silicon single crystal substrate after the amorphous silicon film 4 is formed at a temperature of 1150 ° C. or higher and 1300 ° C. or lower in a carbon-containing atmosphere. The RTA processing time can be 10 to 60 seconds. Further, the carbon-containing atmosphere in this case can be the same atmosphere as the step of adhering the carbon 2 to the surface of the silicon single crystal substrate 1. In this way, the SiC single crystal base film 3 becomes a seed crystal, and Si in the amorphous silicon film 4 reacts with C in the atmosphere to grow in a solid phase, and the amorphous silicon changes to a SiC single crystal structure.

The mechanism at this time is not clear, but the sublimation temperature of amorphous silicon is lower than that of single crystal silicon, and carbon (C) in the atmosphere diffuses into amorphous silicon, causing the sublimated Si and C to react and SiC. It is presumed that the solid-phase growth of the SiC single crystal proceeds upward from the contact surface of the single crystal base film 3. At this time, even if the crystal structure of the amorphous silicon changes to a 3C-SiC single crystal, the crystal structure is the same as that of the seed crystal (SiC single crystal base film 3), so that it is not subjected to stress due to the difference in thermal expansion coefficient and is of high quality. Can be the SiC single crystal film 5.

After that, in the case of making a thicker film, the process returns to the step of forming the amorphous silicon film 4 of FIG. 1 (d) again, the step of forming the amorphous silicon film 4 and the solidification of FIG. 1 (e). The step of converting the amorphous silicon film 4 into a SiC single crystal film 5 by phase growth can be repeated twice or more to obtain the desired thickness of the SiC single crystal, and the thick SiC single crystal film having high crystallinity can be obtained. Can be obtained. At this time, in the step of forming the amorphous silicon film 4, since the thickness of the underlying SiC single crystal is thicker than the initial thickness, the amorphous silicon film 4 is formed by the step of forming the amorphous silicon film 4 and the solid phase growth. In the step of repeating the step of forming the SiC single crystal film 5, the thickness of the SiC single crystal formed at one time can be made thicker, and a thicker amorphous silicon film can be formed in a few steps. By doing so, it is possible to form the SiC single crystal film 5 having a thickness of, for example, 15 nm or more.

In this way, as shown in FIG. 1 (f), it is possible to obtain a semiconductor substrate 10 having a SiC single crystal film 5 having low defects and high crystallinity on a silicon single crystal substrate 1. Since the amorphous silicon film 4 is grown on the SiC single crystal base film 3 and the SiC single crystal film 5 is grown by carbon injection and solid phase growth by RTA, the defect on the SiC single crystal base film 3 is directly above. It is not introduced into the solid-phase grown SiC single crystal film 5, and is a semiconductor substrate provided with a thick SiC single crystal film 5 having low defects and high crystallinity on the silicon single crystal substrate 1.

By using the silicon single crystal substrate 1 having the SiC single crystal film 5 thus obtained as the base substrate of the SOI wafer and applying the SiC single crystal film to the insulating film, the leakage current can be suppressed to the maximum. Further, an SOI wafer having good heat conduction can be obtained. The method for manufacturing the SOI wafer is not particularly limited.

Further, the silicon single crystal substrate 1 having the SiC single crystal film 5 can be used as a starting substrate instead of the conventional GaN substrate or ZnO substrate, and the compound semiconductor film can be formed on the SiC single crystal film 5. In this case, the SiC single crystal film 5 can function as a buffer layer, which makes it possible to form a highly crystalline compound semiconductor film. The method for forming the compound semiconductor film is not particularly limited. A MOCVD method, an HVPE method, or the like can be adopted.

Hereinafter, the present invention will be specifically described with reference to examples, but this does not limit the present invention.

A silicon single crystal substrate having the following specifications was prepared (common to both Examples and Comparative Examples).
Diameter 200 mm, plane orientation (100), P type, normal resistance,
Oxygen concentration: 12ppma (JEITA),
Crystal region: V region.

(Example 1)
A 3C-SiC single crystal film was formed on a silicon single crystal substrate by the flow shown in FIG.

First, the step of adhering carbon to the surface of the silicon single crystal substrate was performed by RTA treatment. In the RTA treatment, the temperature is raised from room temperature to 800 ° C., and the RTA treatment conditions are set.
Holding temperature: 800 ° C,
Holding time: 20 seconds,
Atmosphere: CH ₄ / (Ar + H ₂ ), carbon concentration 1.4%,
And said.

Next, a step of carbonizing the surface of the silicon single crystal substrate to which carbon was attached to form a thin 3C-SiC single crystal undercoat on the surface of the silicon single crystal substrate was performed by RTA treatment. The RTA processing conditions are
Holding temperature: 1200 ° C,
Holding time: 10 seconds,
Atmosphere: CH ₄ / (Ar + H ₂ ), carbon concentration 1.4%,
And said. As a result, a 3C-SiC single crystal film (base film) having a thickness of 2 nm could be formed.

Next, a step (first time) of forming an amorphous silicon film on a 3C-SiC single crystal film aiming at a thickness of 5 nm was performed. Using a CVD device, set the film formation conditions
Raw material gas: SiH ₄ ,
Growth temperature: 530 ° C,
Growth time: 2.5 minutes,
Amorphous silicon was formed by vapor deposition. The growth rate was 2 nm / min. As a result, an amorphous silicon film having a thickness of 5 to 6 nm was formed.

Next, a step (first time) of forming a 3C-SiC single crystal film from the amorphous silicon film by solid-phase growth was performed. Here, in order to prevent polycrystallization during the solid phase growth step, a single-stage RTA treatment was adopted. The RTA processing conditions are
Temperature rise: From 600 ° C to 1150 ° C, temperature rise rate 50 ° C / sec,
Holding temperature: 1150 ° C,
Holding time: 30 seconds,
Atmosphere: CH ₄ / (Ar + H ₂ ), carbon concentration 1.4%,
And said. The film thickness of the 3C-SiC single crystal film after the first solid-phase growth was 6.8 nm.

Next, the formation of the amorphous silicon film for the second time and the formation of the 3C-SiC single crystal film by the solid phase growth for the second time were carried out under the same conditions as those for the first time. The film thickness of the 3C-SiC single crystal film after the second solid-phase growth was 12.3 nm.

When the cross-sectional TEM observation of the obtained 3C-SiC single crystal film was carried out, it was found that a thick 3C-SiC single crystal film could be formed as shown in FIG.

Next, the crystallinity of the obtained 3C-SiC single crystal film was evaluated. At this time, by using XRD In-Plane and scanning 2θχ / φ in the in-plane direction near the X-ray incident angle, which is the total reflection condition for the sample surface, diffraction lines can be generated with high sensitivity even with an extremely thin film of several nm. It can be detected (detection from the crystal plane perpendicular to the sample surface). As a result, as shown in FIG. 6, 3C-SiC (200) plane and (400) plane were confirmed on the Si (400) plane.

In Example 1, as described above, a 3C-SiC single crystal base film having a thickness of 2 nm is formed by carbonizing a silicon single crystal substrate, and then 3C is formed by forming amorphous silicon having a thickness of 5 nm and solid-phase growth. -Conversion to a SiC single crystal film is repeated twice. On the other hand, as explained above, the thickness of the 3C-SiC single crystal film at each stage and the thickness of each layer that can be confirmed from the TEM observation photograph (enlarged image of FIG. 5) seem to match (correspond). Looks like it doesn't. This is due to the mechanism of solid phase growth. That is, in the reaction of converting amorphous silicon formed on a SiC single crystal base film into a SiC single crystal film by solid phase growth, the supply of carbon (C) to the amorphous silicon is on the base side and the vapor phase side (amorphous). It is done from both sides of the silicon surface side). As a result, apparently (in the TEM image), the distinction (boundary) between the SiC single crystal film formed by solid-phase growth and the SiC single crystal base film becomes unclear. At the stage where the first solid-phase growth is completed, as described above, the entire SiC single crystal film is in a state of being formed with a thickness of about 6.8 nm. After that, when the formation of the amorphous silicon and the solid phase growth are performed for the second time, the formation of the SiC single crystal film proceeds by the same mechanism as the first time. At the stage where the second solid phase growth is completed, the entire SiC single crystal film is in a state of being formed at 12.3 nm, but the SiC single crystal film formed by the second solid phase growth is from the lower layer side. The growth on the lower layer side due to the supply of carbon and the solid phase growth on the surface side due to the supply of carbon from the surface side (gas phase) proceed at the same time. Since the growth on the lower layer side also proceeds to take in the SiC single crystal on the lower layer side, when TEM observation is performed after performing two solid phase growths, the first solid phase growth is apparently completed. The SiC single crystal film formed at the stage of 6.8 nm becomes thinner (corresponding to "5.0 nm" in the enlarged image of FIG. 5), and at the same time, the SiC single crystal film formed by the second solid phase growth On the surface side, a SiC single crystal film (corresponding to "1.5 nm" in the enlarged image of FIG. 5) grown toward the surface side due to the supply of carbon from the gas phase can be observed. This also applies to the data of Example 2 below.

(Example 2)
A 3C-SiC single crystal film was formed on the silicon single crystal substrate by the flow shown in FIG. 7. The conditions for the RTA treatment (first and second) in the step of forming the 3C-SiC single crystal film from the amorphous silicon film by solid phase growth were the same as in Example 1 except that the holding temperature was 1200 ° C. , 3C-SiC single crystal film was formed and evaluated. The thickness of the 3C-SiC single crystal film after the first solid phase growth was 8.8 nm, and the thickness of the 3C-SiC single crystal film after the second solid phase growth was 16.8 nm.

When the cross-sectional TEM observation of the obtained 3C-SiC single crystal film was carried out, it was found that a thick 3C-SiC single crystal film could be formed as shown in FIG.

When the crystallinity of the obtained 3C-SiC single crystal film was evaluated, as shown in FIG. 9, the Si (400) plane, the 3C-SiC (200) plane and the (400) plane were evaluated as in Example 1. ) The surface was confirmed.

(Comparative example)
In the flow shown in FIG. 10, the RTA treatment with a carbon-containing atmosphere was repeated without forming the amorphous silicon film of Examples 1 and 2 and the formation of the 3C-SiC single crystal film by solid-phase growth, and the 3C-SiC single crystal was formed. A film was formed.
First, the RTA processing conditions
Holding temperature: 1200 ° C,
Holding time: 10 seconds,
Atmosphere: CH ₄ / (Ar + H ₂ ), carbon concentration 2.0%,
When the first RTA treatment was performed, a 3C-SiC single crystal film of about 2 nm could be formed. After that, the RTA treatment under the same conditions as the first time was repeated twice except that the holding time was 30 seconds. FIG. 11 shows the cross-sectional TEM observation results of the 3C-SiC single crystal film obtained in the comparative example. When the SiC single crystal film was formed by carbonizing a silicon single crystal substrate by RTA treatment as in the comparative example, even if it was repeated a plurality of times, only a total thickness of 2.5 nm could be formed. The results of the crystallinity evaluation are shown in FIG.

As can be seen from the comparison between Examples 1 and 2 and Comparative Examples, according to the examples of the present invention, a thick SiC single crystal film having low defects and high crystallinity can be easily formed on a silicon single crystal substrate. can.

The present invention is not limited to the above embodiment. The above-described embodiment is an example, and any of the above-described embodiments having substantially the same configuration as the technical idea described in the claims of the present invention and having the same effect and effect is the present invention. Is included in the technical scope of.

1 ... Silicon single crystal substrate, 2 ... Attached carbon, 3 ... SiC single crystal base film,
4 ... Amorphous silicon, 5 ... SiC single crystal film, 10 ... Semiconductor substrate,
11 ... Support substrate, 12 ... Insulation layer, 13 ... SOI layer, 14 ... Base substrate,
20 ... SOI wafer.

Next, the crystallinity of the obtained 3C-SiC single crystal film was evaluated. At this time, by using XRD In-Plane and scanning 2θ / φ in the in-plane direction near the X-ray incident angle, which is the total reflection condition for the sample surface, diffraction lines can be generated with high sensitivity even with an extremely thin film of several nm. It can be detected (detection from the crystal plane perpendicular to the sample surface). As a result, as shown in FIG. 6, 3C-SiC (200) plane and (400) plane were confirmed on the Si (400) plane.

Claims (11)

A method for manufacturing a semiconductor substrate having a SiC single crystal film on its surface.
The process of adhering carbon to the surface of a silicon single crystal substrate,
A step of carbonizing the surface of the silicon single crystal substrate to which the carbon is attached to form a SiC single crystal base film, and
The step of forming an amorphous silicon film on the SiC single crystal base film and
A method for manufacturing a semiconductor substrate, which comprises a step of using the SiC single crystal base film as a seed crystal and using the amorphous silicon film as a SiC single crystal film by solid phase growth. The method for manufacturing a semiconductor substrate according to claim 1, wherein in the step of adhering carbon to the surface of the silicon single crystal substrate, the silicon single crystal substrate is subjected to RTA treatment at 800 ° C. or lower in a carbon-containing atmosphere. In the step of forming the SiC single crystal base film, the silicon single crystal substrate is subjected to RTA treatment at 1150 ° C. to 1300 ° C. in a carbon-containing atmosphere to form a SiC single crystal base film having a thickness of 7 nm or less. The method for manufacturing a semiconductor substrate according to claim 1 or 2, wherein the semiconductor substrate is characterized. In the step of forming the amorphous silicon film, an amorphous silicon film having a thickness of 3 times or less the thickness of the SiC single crystal undercoat is vapor-phased on the SiC single crystal undercoat at a growth temperature of 300 to 600 ° C. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 3, wherein the semiconductor substrate is grown. Claims 1 to 4 are characterized in that, in the step of converting an amorphous silicon film into a SiC single crystal film by solid phase growth, the silicon single crystal substrate is subjected to RTA treatment at 1150 ° C. to 1300 ° C. in a carbon-containing atmosphere. The method for manufacturing a semiconductor substrate according to any one of the above. The semiconductor according to any one of claims 1 to 5, wherein the step of forming the amorphous silicon film and the step of forming the amorphous silicon film into a SiC single crystal film are repeated two or more times. Substrate manufacturing method. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 6, wherein the SiC single crystal film is formed to be thicker than 15 nm. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 7, wherein the SiC single crystal base film and the SiC single crystal film are 3C-SiC. A silicon single crystal substrate having a SiC single crystal film manufactured by the method for manufacturing a semiconductor substrate according to any one of claims 1 to 8 is used as a base substrate for an SOI wafer to manufacture an SOI wafer. A method for manufacturing an SOI wafer. A silicon single crystal substrate having a SiC single crystal film manufactured by the method for manufacturing a semiconductor substrate according to any one of claims 1 to 8 is used as a starting substrate, and a compound semiconductor film is formed on the SiC single crystal film. A method for manufacturing a semiconductor substrate, characterized in that it is formed. It is an SOI wafer,
It has a support substrate, an insulating layer on the support substrate, and an SOI layer on the insulating layer.
The support substrate is a silicon single crystal substrate, and the support substrate is a silicon single crystal substrate.
An SOI wafer characterized in that the insulating layer is made of a 3C-SiC single crystal film.

Images