TW202142746A - Semiconductor substrate manufacturing method, SOI wafer manufacturing method, and SOI wafer capable of forming a SiC single crystal film having low defect, high crystallinity, and thick film on a single crystal silicon substrate - Google Patents

Abstract

The present invention provides a semiconductor substrate manufacturing method capable of forming a SiC single crystal film having low defect, high crystallinity, and thick film on a single crystal silicon substrate. The method of manufacturing a semiconductor substrate having a SiC single crystal film on the surface includes the following steps: a carbon adhesion step for adhering carbon to a surface of a single crystal silicon substrate; a SiC single crystal underlayer film forming step for forming an SiC single crystal underlayer film by carbonizing the surface of the single crystal silicon substrate to which the carbon is adhered; an amorphous silicon film forming step for forming an amorphous silicon film on the SiC single crystal underlayer film; and a SiC single crystal film growing step for using the SiC single crystal underlayer film as a seed crystal to transform the amorphous silicon film into a SiC single crystal film by solid phase growth.

Description

Semiconductor substrate manufacturing method, SOI wafer manufacturing method, and SOI wafer

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

Compared with Si single crystal substrates, SiC single crystal substrates are materials that can realize semiconductor devices with low loss, excellent high-frequency characteristics, high withstand voltage, high thermal conductivity, and high breakdown electric field. In Figure 13, the physical properties of the main semiconductor materials are shown.

Patent Document 1 discloses that the SOI substrate is heated in a hydrocarbon-based gas environment to change the surface Si layer into a single crystal SiC film, and the single crystal SiC film is used as a seed layer to epitaxially grow to become single crystal SiC. Substrate (but the base substrate is an SOI substrate). _{In addition, Patent Document 2 discloses that a silicon oxide film (SiO 2} ) that functions as an embedded oxide film is formed on the entire surface of a single crystal silicon substrate that functions as a support substrate, and a SiC film is formed thereon. Furthermore, Patent Document 3 discloses that as a supporting substrate of a compound semiconductor substrate, a semiconductor substrate having a single crystal SiC film on the surface is used. [Related Technical Documents] [Patent Documents]

Patent Document 1: Japanese Patent Laid-Open No. 2007-123675 Patent Document 2: Japanese Patent Laid-Open No. 2008-41830 Patent Document 3: Japanese Patent Laid-Open No. 2014-76925

[Problems to be solved by the present invention]

In Patent Document 1, a method for forming a single crystal SiC layer by epitaxial growth using a single crystal SiC film as a seed layer is disclosed. In the case of this process, the lattice constant mismatch rate of Si (0.543nm)/3C-SiC (0.453nm) in the first layer is 20%. In order to alleviate this situation, a large number of defects are induced. If the epitaxial growth is grown on the seed crystal with a large number of defects in this way, there are problems such as the generation of epitaxial defects originating from the defects on the seed crystal. In the case of epitaxial growth, the film thickness of the SiC single crystal film can be increased, but a SiC single crystal film with low defects and good crystallinity cannot be obtained.

Patent Document 2 discloses an SOI substrate having a silicon oxide film (SiO ₂ ) that functions as an embedded oxide film, and a SiC film formed thereon or mixed with SiC bonding as a layer for forming lattice strain SiC contains a layer, but there is no description about the method of forming the SiC single crystal layer.

Patent Document 3 discloses a method of forming a GaN film on a silicon substrate with a SiC single crystal thin film as a support substrate, but the SiC single crystal thin film does not serve as a buffer layer. In addition, the defects of the SiC single crystal layer itself and the method of forming the SiC single crystal layer are not mentioned.

In addition, SOI power ICs for high withstand voltage applications exceeding 600V must have a thick BOX layer of several μm. These SOI power components or RF components have good insulation and withstand voltage characteristics, and the components generate large amounts of heat, so it is required to also dissipate heat to the base substrate side. However, the thick SiO ₂ film has poor heat conduction, resulting in heat storage. Therefore, in the past, when designing devices, metal electrodes were placed on the surface of the SOI layer side of the device, and a water-cooled radiator was placed on the upper side. In order to become such a complicated structure, it must go through a complicated manufacturing process, which is disadvantageous in terms of cost and productivity.

As such, in a single crystal silicon substrate with a SiC single crystal film, it is required to manufacture a single crystal silicon substrate with a low defect, high crystallinity, and thick SiC single crystal film. In addition, an SOI wafer with a simple structure, which minimizes leakage current, and has high heat dissipation to the base substrate side is required.

In order to solve the above-mentioned problems, the object of the present invention is to provide a method for manufacturing a semiconductor substrate capable of forming a SiC single crystal film with low defects, high crystallinity, and thick film on a single crystal silicon substrate, and a semiconductor substrate with a SiC single crystal film SOI wafers on monocrystalline silicon substrates. [Technical means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides a method for manufacturing a semiconductor substrate. The method for manufacturing a semiconductor substrate with a SiC single crystal film on the surface includes the following steps: a carbon adhesion step, making carbon adhere to the surface of the single crystal silicon substrate; SiC single crystal underlayer film The forming step is to carbonize the surface of the single crystal silicon substrate with the carbon attached to form an SiC single crystal underlayer film; the amorphous silicon film forming step is to form an amorphous silicon film on the SiC single crystal underlayer film; and SiC single crystal In the film growth step, the SiC single crystal underlayer film is used as a seed crystal, and the amorphous silicon film is turned into a SiC single crystal film by solid phase growth.

According to the manufacturing method of these semiconductor substrates, the amorphous silicon film is grown on the SiC single crystal underlayer film, and the RTA is used for carbon injection and solid phase growth to grow the SiC single crystal film. Therefore, the SiC single crystal underlayer film is grown The defects of SiC are not introduced into the SiC single crystal film grown in the solid phase directly above. It can be manufactured on a single crystal silicon substrate, a semiconductor substrate with a low defect, high crystallinity, and thick SiC single crystal film.

In this case, the following semiconductor substrate manufacturing method can be used: in the carbon adhesion step of attaching carbon to the surface of the single crystal silicon substrate, the single crystal silicon substrate is subjected to a temperature of 800°C or less in a carbon-containing gas environment RTA processing.

As a result, carbon can be more uniformly attached to the surface of the single crystal silicon substrate in a more sufficient amount, so a higher crystallinity SiC single crystal underlayer film can be formed by subsequent steps, and a solid phase can be formed on it. The crystallinity of the grown SiC single crystal film is higher.

At this time, it can be a method of manufacturing the following semiconductor substrate: In the step of forming the SiC single crystal underlayer film, the single crystal silicon substrate is formed by RTA treatment at 1150°C to 1300°C in a carbon-containing gas atmosphere. SiC single crystal underlayer film with a thickness of 7nm or less.

Thereby, a SiC single crystal underlayer film with higher crystallinity can be obtained, and the crystallinity of the SiC single crystal film formed by solid phase growth on the upper layer can be higher.

At this time, it can be a method of manufacturing the following semiconductor substrate: in the step of forming the amorphous silicon film, an amorphous silicon film having a thickness less than three times the thickness of the SiC single crystal underlayer film is grown at 300-600°C At a temperature, vapor phase growth on the SiC single crystal underlayer film.

If the thickness of the amorphous silicon film is within this range, it can be a silicon film that more stably maintains an amorphous form, and the crystallinity when it becomes a SiC single crystal film by solid phase growth can be stabilized and higher.

In this case, it can be a manufacturing method of the following semiconductor substrate: in the SiC single crystal film growth step in which the amorphous silicon film becomes a SiC single crystal film by the solid phase growth, the single crystal silicon substrate is coated with carbon Perform RTA treatment at 1150℃～1300℃ in a gas environment.

Thereby, a SiC single crystal film with higher crystallinity can be reliably formed.

At this time, it can be a method of manufacturing a semiconductor substrate in which the step of forming the amorphous silicon film and the step of growing the SiC single crystal film are repeated twice or more.

Thereby, a SiC single crystal film with low defects and high crystallinity can be formed in a thick layer.

In this case, it can be a manufacturing method of a semiconductor substrate in which the SiC single crystal film is formed to be thicker than 15 nm.

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

At this time, it can be a method of manufacturing a semiconductor substrate that the SiC single crystal underlayer film and the SiC single crystal film are 3C-SiC.

According to the present invention, these semiconductor substrates can be suitably manufactured.

At this time, it can be a method of manufacturing an SOI wafer: the single crystal silicon substrate with a SiC single crystal film manufactured by the above-mentioned method of manufacturing a semiconductor substrate is used as the base substrate of the SOI wafer to manufacture the SOI wafer.

Thereby, it is possible to manufacture SOI wafers with high heat dissipation properties to the base substrate side with suppressed leakage current.

In this case, the following semiconductor substrate manufacturing method can be used: the single crystal silicon substrate with the SiC single crystal film manufactured by the above semiconductor substrate manufacturing method is used as the initial substrate, and the compound semiconductor is formed on the SiC single crystal film membrane.

Thereby, a low-cost single crystal silicon substrate can be used, and a SiC single crystal film with high crystallinity can be used as a buffer layer to form a compound semiconductor film.

The present invention, in addition, provides an SOI wafer having a supporting substrate, an insulating layer on the supporting substrate, and an SOI layer on the insulating layer; the supporting substrate is a single crystal silicon substrate; the insulating layer is made of 3C-SiC single crystal Membrane composition.

According to these SOI wafers, the leakage current is suppressed, and it becomes an SOI wafer with high heat dissipation to the base substrate side. [Effects of the invention]

As mentioned above, according to the method of manufacturing a semiconductor substrate of the present invention, an amorphous silicon film is grown on a SiC single crystal underlayer film, and carbon implantation and solid phase growth are performed by RTA to grow the SiC single crystal film. The defects on the underlayer film are not introduced into the SiC single crystal film that is solid-phase grown directly above, and can be manufactured on a single crystal silicon substrate with a low defect, high crystallinity, and thick SiC single crystal film semiconductor substrate. In addition, the SOI wafer according to the present invention is an SOI wafer that has a reduced leakage current and high heat dissipation to the base substrate side.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to these aspects.

As mentioned above, it is required to form a semiconductor substrate with a low defect, high crystallinity, and thick SiC single crystal film on a single crystal silicon substrate, and an SOI wafer with a single crystal silicon substrate with a SiC single crystal film.

The inventors of the present case have repeatedly examined the above-mentioned issues and found that: a method for manufacturing a semiconductor substrate, which manufactures a semiconductor substrate with a SiC single crystal film on the surface, includes the following steps: a carbon adhesion step to make carbon adhere to the single crystal silicon substrate The surface of the SiC single crystal underlayer film forming step is to carbonize the surface of the single crystal silicon substrate to which the carbon is attached to form the SiC single crystal underlayer film; the amorphous silicon film forming step is to form a non-crystalline SiC single crystal underlayer film A crystalline silicon film; and a SiC single crystal film growth step, using the SiC single crystal underlayer film as a seed crystal, and making the amorphous silicon film into a SiC single crystal film by solid phase growth; by the manufacturing method of the semiconductor substrate, it can be manufactured On a single crystal silicon substrate, a semiconductor substrate with a SiC single crystal film with low defects, high crystallinity, and a thick film, completes the present invention.

In addition, the inventors of the present case discovered: an SOI wafer with a supporting substrate, an insulating layer on the supporting substrate, and an SOI layer on the insulating layer; the supporting substrate is a single crystal silicon substrate; the insulating layer is composed of 3C- It is composed of a SiC single crystal film; this SOI wafer becomes an SOI wafer that has suppressed leakage current and has high heat dissipation to the base substrate side, thereby completing the present invention.

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

The inventors of this case focused on: If it is a semiconductor substrate with a low defect, high quality, and thick film (for example, more than 15nm) SiC single crystal film, when applied to an SOI wafer, the leakage current can be reduced and improved Thermal conductivity can be used as a buffer layer for compound semiconductor substrates. In the method of forming a SiC single crystal film by carbonizing the surface of a single crystal silicon substrate, it is difficult to form a thick SiC single crystal film. In order to solve these problems, after careful review, it was found that carbon was attached to the surface of the single crystal silicon substrate, and a thin layer of SiC single crystal underlayer film was formed by RTA treatment in a carbon-containing gas environment, and a thick layer of amorphous was formed on it. The silicon film is grown in the vapor phase at a low temperature, and then subjected to RTA treatment, whereby the SiC single crystal underlayer film is used as a seed crystal, and the amorphous silicon is changed to a SiC single crystal through solid phase growth, resulting in high crystallinity and thicker film than in the past. Thick SiC single crystal film. Furthermore, the present invention was completed by discovering the following: After vapor-growing a thick layer of amorphous silicon on the surface of a SiC single crystal film, it is transformed into a SiC single crystal by solid phase growth, and by repeating this step, it can be Obtained a high-quality SiC single crystal film with a thickness of more than 15nm that was not available in the past.

(Semiconductor substrate) In FIG. 2, a semiconductor substrate obtained by the method of manufacturing a semiconductor substrate of the present invention is shown. As shown in FIG. 2, the semiconductor substrate 10 has an SiC single crystal underlayer film 3 and a SiC single crystal film 5 on the single crystal silicon substrate 1. The type of the single crystal silicon substrate 1 used is not particularly limited. In addition, the SiC single crystal underlying film 3 and the SiC single crystal film 5 may be 3C-SiC. These SiC single crystal films 5 are low-defect, high-crystallinity, thick-film films compared to conventional SiC single crystal films. In addition, these semiconductor substrates 10 can be applied as follows.

(SOI wafer) In Fig. 3, the SOI wafer of the present invention is shown. As shown in FIG. 3, the SOI wafer 20 of the present invention uses the above-mentioned semiconductor substrate 10 as the base substrate 14. The supporting substrate 11 and the insulating layer 12 respectively correspond to the single crystal silicon substrate 1 and SiC in the semiconductor substrate 10. The single crystal underlayer film 3 and the SiC single crystal film 5. On the other hand, the SiC single crystal underlayer film 3 and the SiC single crystal film 5 used as the insulating layer 12 have an SOI layer 13.

Compared with SiO ₂ , 3C-SiC has a thermal conductivity (W/cm·K) about 3.5 times higher: 3C-SiC/SiO ₂ =4.9/1.38=about 3.5 times; therefore, it is similar to the SOI wafer ground of the present invention , 3C-SiC is used as the insulating layer, the heat dissipation to the base substrate side is good, and it becomes advantageous in terms of heat dissipation. It is no longer necessary to install a metal electrode on the surface of the device on the SOI layer side and place a water-cooled heat sink on the upper side of the SOI wafer with a BOX layer in the past.

(Semiconductor substrate on which compound semiconductor film is formed) It is also possible to use the semiconductor substrate 10 shown in FIG. 2 on which a compound semiconductor film such as a group III-V semiconductor is provided. The semiconductor substrate manufactured by the manufacturing method of the semiconductor substrate of the present invention can be a semiconductor substrate having a SiC single crystal film with high crystallinity and a thick film, and thus the SiC single crystal film can be used as a buffer layer.

(Method of manufacturing semiconductor substrate) Next, the manufacturing method of the semiconductor substrate of the present invention will be described. FIG. 1 is a flowchart and conceptual diagram showing the outline of the manufacturing method of the semiconductor substrate of the present invention. Hereinafter, each step will be explained.

First, a single crystal silicon substrate 1 is prepared (FIG. 1(a)). The single crystal silicon substrate 1 used is not particularly limited. For example, under the current situation, as a silicon substrate for manufacturing a GaN substrate, a single crystal silicon substrate of a V crystal region is used, and these single crystal silicon substrates can be used. A single crystal silicon substrate with 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. 1(b), a step of attaching carbon 2 to the surface of the single crystal silicon substrate 1 is performed. By performing this step, a uniform and sufficient amount of carbon 2 can be attached to the surface of the single crystal silicon substrate 1, and thereafter, the step of forming a SiC single crystal underlayer film by carbonizing the surface of the single crystal silicon substrate 1. It can form a SiC single crystal underlayer film that can act as a seed crystal. In this step, it is advisable to subject the single crystal silicon substrate 1 to RTA treatment in a carbon-containing gas environment. As the carbon-containing gas environment, for example, a carbon-containing gas such as CH ₄ , C ₂ H ₄ , C ₃ H ₈ and the like can be used, and the carbon concentration can be 1% or more of H ₂ or a mixed gas environment of Ar+H _2. RTA treatment should be performed at a lower temperature below 800°C, more preferably 700-800°C for 20-40 seconds.

Next, as shown in FIG. 1(c), a step of forming the SiC single crystal underlayer film 3 is performed: the surface of the single crystal silicon substrate 1 to which carbon 2 is adhered is carbonized to become 3C-SiC, and the SiC single crystal underlayer film 3 is formed . In this step, the single crystal silicon substrate is preferably subjected to RTA treatment at 1150° C. to 1300° C. in a carbon-containing gas environment to form a SiC single crystal underlayer film 3 with a thickness of 7 nm or less. As the carbon-containing gas environment, for example, CH ₄ , C ₂ H ₄ , C ₃ H _8, etc. can be used to make the carbon concentration 1% or more H ₂ or Ar+H ₂ mixed gas environment. The RTA treatment, for example, is more preferably 1150°C or higher and 1300°C or lower for 10 to 100 seconds. By such RTA treatment, the Si sublimated from the single crystal silicon substrate can react with the carbon (C) attached to the surface and the carbon (C) in the gas atmosphere to form about 7nm on the surface of the single crystal silicon substrate 1. The following thin-layer SiC single crystal underlayer film 3.

In the case of the sublimation method, if the Si supply becomes insufficient, the growth stops. When the RTA temperature is 1300°C, the SiC single crystal grows to about 7 nm. In addition, when the RTA temperature is less than 1150°C, the thickness of the SiC single crystal is less than 2 nm. In the subsequent steps, in order to make the SiC single crystal underlayer film 3 function more effectively as a seed crystal, it is preferably about 2 nm to 7 nm.

Next, as shown in FIG. 1(d), a step of forming an amorphous silicon film 4 is performed: an amorphous silicon film 4 is formed on the SiC single crystal underlying film 3. In this step, a CVD device can be used to supply the raw material gas of a silane-based gas (such as silane, trichlorosilane, etc.) to cause the vapor phase growth of amorphous silicon at 300°C to 600°C. The thickness of the amorphous silicon film 4 formed at this time is preferably three times the thickness of the SiC single crystal underlayer film 3 or less. If the thickness is the same, the amorphous silicon film 4 can be stably formed, and by the subsequent RTA treatment, a stable and high crystallinity SiC single crystal can be obtained.

Next, as shown in FIG. 1(e), a step of converting this amorphous silicon film 4 into 3C-SiC by solid phase growth to make it into a SiC single crystal film 5 is performed. In this step, the single crystal silicon substrate after the amorphous silicon film 4 is formed is preferably subjected to RTA treatment at a temperature of 1150°C or more and 1300°C or less in a carbon-containing gas environment. The RTA treatment time can be 10-60 seconds. In addition, the carbon-containing gas environment in this case can be the same gas environment as the step of attaching carbon 2 to the surface of the single crystal silicon substrate 1. In this way, the SiC single crystal underlayer film 3 becomes a seed crystal, and the Si in the amorphous silicon film 4 reacts with C in the gas atmosphere and grows in a solid phase, thereby changing the amorphous silicon to a SiC single crystal structure.

The mechanism at this time is not clear, but it is speculated that the sublimation temperature of amorphous silicon is lower than that of single crystal silicon. Carbon (C) in the gas atmosphere diffuses into the amorphous silicon, so the sublimed Si reacts with C to make SiC The solid phase growth of the single crystal develops upward from the contact surface of the SiC single crystal underlayer film 3. At this time, even if the crystalline structure of amorphous silicon is changed to 3C-SiC single crystal, the crystalline structure is still the same as the seed crystal (SiC single crystal underlayer film 3), so it is not subject to the stress caused by the difference in thermal expansion coefficient and becomes high-quality SiC single crystal film 5.

After that, when it becomes a thicker film, it returns to the step of forming the amorphous silicon film 4 in FIG. 1(d). The step of forming the crystalline silicon film 4 into the SiC single crystal film 5 is repeated twice or more to achieve the target thickness of the SiC single crystal, and a thick SiC single crystal film with high crystallinity can be obtained. At this time, in the step of forming the amorphous silicon film 4, the thickness of the SiC single crystal of the base becomes thicker than the initial thickness. 4 Repeating the steps of forming the SiC single crystal film 5 can also make the thickness of the SiC single crystal formed in one pass thicker, and it is possible to form a thicker amorphous silicon film with a small number of steps. In this way, for example, the SiC single crystal film 5 having a thickness of 15 nm or more can be formed.

In this way, as shown in FIG. 1(f), a semiconductor substrate 10 having a SiC single crystal film 5 with low defects and high crystallinity on a single crystal silicon substrate 1 can be obtained. The amorphous silicon film 4 is grown on the SiC single crystal underlayer film 3, and carbon implantation and solid phase growth are performed by RTA so that the SiC single crystal film 5 is grown. Therefore, the defects on the SiC single crystal underlayer film 3 are not introduced to The SiC single crystal film 5 grown in the solid phase directly above becomes a semiconductor substrate with a low defect, high crystallinity, and thick SiC single crystal film 5 on the single crystal silicon substrate 1.

The single crystal silicon substrate 1 with the SiC single crystal film 5 obtained in this way is used as the base substrate of the SOI wafer, and the SiC single crystal film is applied to the insulating film, whereby leakage current can be suppressed to the utmost extent, and the heat conduction is good. SOI wafers. In addition, the method of manufacturing SOI wafers is not particularly limited.

In addition, the single crystal silicon substrate 1 with the SiC single crystal film 5 may be used as an initial substrate instead of the conventional GaN substrate and ZnO substrate, and a compound semiconductor film can be formed on the SiC single crystal film 5. In this case, the SiC single crystal film 5 can be used as a buffer layer, whereby a compound semiconductor film with high crystallinity can be formed. In addition, the method of forming the compound semiconductor film is not particularly limited. The MOCVD method, HVPE method, etc. can be used. [Example]

Hereinafter, the present invention will be specifically explained by citing examples, but the present invention is not limited to these examples.

A single crystal silicon substrate of the following specifications (common to the examples and comparative examples) was prepared. Diameter 200mm, face orientation (100), P type, general resistance; Oxygen concentration: 12ppma (JEITA); Crystallization area: V crystallization area.

(Example 1) By the process shown in FIG. 4, a 3C-SiC single crystal film is formed on a single crystal silicon substrate.

First, by RTA treatment, a step of attaching carbon to the surface of the single crystal silicon substrate is performed. In the RTA treatment, the temperature is raised from room temperature to 800°C, and the RTA treatment conditions are: holding temperature: 800°C; holding time: 20 seconds; gas environment: CH ₄ /(Ar+H ₂ ), carbon concentration 1.4%.

Then, by RTA treatment, a step of forming a 3C-SiC single crystal underlayer film is performed: the surface of the single crystal silicon substrate with carbon attached is carbonized, and a thin layer of 3C-SiC single crystal underlayer film is formed on the surface of the single crystal silicon substrate. The RTA treatment conditions were: Holding temperature: 1200°C; Holding time: 10 seconds; Gas environment: CH ₄ /(Ar+H ₂ ), carbon concentration 1.4%. Thereby, a 3C-SiC single crystal film (underlying film) with a thickness of 2 nm was formed.

Next, on the 3C-SiC single crystal film, a step of forming an amorphous silicon film (the first time) is performed with a thickness of 5 nm as the target. Using a CVD device, the film forming conditions are as follows: raw material gas: SiH ₄ ; growth temperature: 530° C.; growth time: 2.5 minutes; vapor phase growth is performed to form a film of amorphous silicon. The growth rate is 2nm/min. In this way, an amorphous silicon film with a thickness of 5-6 nm is formed.

Next, a step of forming a 3C-SiC single crystal film from an amorphous silicon film by solid phase growth (first time) is performed. Here, in order to prevent polycrystallization in the solid phase growth step, a single-stage RTA treatment is used. The RTA treatment conditions are: heating: from 600°C to 1150°C, heating rate 50°C/sec; holding temperature: 1150°C; holding time: 30 seconds; gas environment: CH ₄ /(Ar+H ₂ ), carbon concentration 1.4 %. The thickness of the 3C-SiC single crystal film after the first solid phase growth was 6.8 nm.

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

After performing TEM observation of the cross-section of the obtained 3C-SiC single crystal film, as shown in FIG. 5, it was found that a thick 3C-SiC single crystal film can be formed.

Next, evaluation of the crystallinity of the obtained 3C-SiC single crystal film was performed. At this time, using XRD In-Plane, the surface of the sample is scanned in the in-plane direction near the X-ray incident angle that becomes the condition of total reflection, so that even the extremely thin film of a few nm can still detect the winding with high sensitivity. Ray (detected from the crystal plane perpendicular to the surface of the sample). As a result, as shown in Fig. 6, on the Si (400) plane, 3C-SiC (200) plane and (400) plane were confirmed.

In addition, in Example 1, as described above, a 3C-SiC single crystal underlayer film with a thickness of 2 nm was formed by carbonization of a single crystal silicon substrate, and then, the formation of amorphous silicon with a thickness of 5 nm and solid phase growth were performed. The conversion to the 3C-SiC single crystal film is repeated twice. On the other hand, the thickness of the 3C-SiC single crystal film at each stage described above and the thickness of each layer that can be confirmed from the TEM observation photograph (the enlarged image of FIG. 5) are not at first glance (corresponding). This is the result of the mechanism of solid phase growth. That is, in the reaction of converting the amorphous silicon formed on the SiC single crystal underlayer film into the SiC single crystal film by solid phase growth, the supply of carbon (C) to the amorphous silicon is from the substrate side and the gas phase It is implemented on both sides of the side (the surface side of the amorphous silicon). As a result, in appearance (in the TEM image), the difference (boundary) between the SiC single crystal film formed by solid phase growth and the SiC single crystal underlayer film becomes unclear. At the end of the first solid phase growth, as described above, the entire SiC single crystal film is formed to a thickness of approximately 6.8 nm. After that, if the second formation of amorphous silicon and solid phase growth are performed, the formation of the SiC single crystal film progresses by the same mechanism as the first. At the end of the second solid phase growth, the entire SiC single crystal film is formed at 12.3 nm. The SiC single crystal film formed in the second solid phase growth is caused by the supply of carbon from the lower layer. The growth on the lower layer side develops simultaneously with the growth of the solid phase on the surface side caused by the carbon supply from the surface side (gas phase). The growth of the lower layer side also develops by absorbing the SiC single crystal on the lower layer side. Therefore, if the TEM observation is performed after the second solid phase growth is performed, the appearance shows that 6.8 is formed at the end of the first solid phase growth. While the SiC single crystal film becomes thinner at nm (corresponding to "5.0nm" in the enlarged image of Fig. 5), on the surface side of the SiC single crystal film formed by the second solid phase growth, it is observed that the gas A SiC single crystal film (corresponding to "1.5 nm" in the enlarged image of FIG. 5) grown on the surface side by supplying phase carbon. This point is also the same in the data of Example 2 below.

(Example 2) By the process shown in FIG. 7, a 3C-SiC single crystal film is formed on a single crystal silicon substrate. The conditions of the RTA treatment (first time and second time) in the step of forming a 3C-SiC single crystal film from an amorphous silicon film by solid phase growth are the holding temperature: 1200°C. Other than that, the same as in the examples 1 In the same manner, the formation and evaluation of a 3C-SiC single crystal film were performed. 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.

After performing TEM observation of the cross-section of the obtained 3C-SiC single crystal film, as shown in FIG. 8, it was found that a thick 3C-SiC single crystal film can be formed.

After performing the evaluation of the crystallinity of the obtained 3C-SiC single crystal film, as shown in FIG. 9, in the same manner as in Example 1, it was confirmed that the 3C-SiC (200) plane and the (400) plane were on the Si (400) plane. noodle.

(Comparative example) By using the process shown in FIG. 10, the carbon-containing gas was repeated without performing the formation of the amorphous silicon film and the formation of the solid phase growth of the 3C-SiC single crystal film of Examples 1 and 2 RTA treatment in the environment to form a 3C-SiC single crystal film. First, let the RTA treatment conditions be: Holding temperature: 1200°C; Holding time: 10 seconds; Gas environment: CH ₄ /(Ar+H ₂ ), carbon concentration 2.0%; After the first RTA treatment, about 2nm 3C-SiC single crystal film. After that, the holding time: 30 seconds, except for this, the RTA treatment under the same conditions as the first time was repeated twice. In Fig. 11, the cross-sectional TEM observation results of the 3C-SiC single crystal film obtained in the comparative example are shown. As in the comparative example, in the case of forming a SiC single crystal film by carbonization of a single crystal silicon substrate by RTA treatment, even if it is repeated several times, only a total thickness of 2.5 nm can be formed. In addition, the results of the evaluation of crystallinity are shown in FIG. 12.

As can be seen from the comparison between Examples 1 and 2 and the comparative example, according to the examples of the present invention, a low-defect, high-crystallinity, thick-film SiC single crystal film can be simply formed on a single crystal silicon substrate.

In addition, the present invention is not limited to the above-mentioned embodiment. The above-mentioned embodiments are only examples, and any form that has substantially the same structure and produces the same effects as the technical idea described in the scope of the invention patent application of the present invention is included in the technical scope of the present invention.

1: Single crystal silicon substrate 2: attached carbon 3: SiC single crystal bottom film 4: Amorphous silicon film 5: SiC single crystal film 10: Semiconductor substrate 11: Support substrate 12: Insulation layer 13: SOI layer 14: Base substrate 20: SOI wafer

1(a)-(f) are flowcharts and conceptual diagrams showing the manufacturing method of the semiconductor substrate of the present invention. Fig. 2 shows a semiconductor substrate obtained by the method of manufacturing a semiconductor substrate of the present invention. Figure 3 shows the SOI wafer of the present invention. Fig. 4 shows a flowchart of Example 1. FIG. 5 shows the cross-sectional TEM observation results of the 3C-SiC single crystal film obtained in Example 1. FIG. 6 shows the result of crystallinity evaluation of the 3C-SiC single crystal film obtained in Example 1. FIG. FIG. 7 shows a flowchart of Embodiment 2. FIG. 8 shows the TEM observation results of the cross-section of the 3C-SiC single crystal film obtained in Example 2. FIG. FIG. 9 shows the crystallinity evaluation results of the 3C-SiC single crystal film obtained in Example 2. Fig. 10 shows a flowchart of a comparative example. Fig. 11 shows the TEM observation results of the cross-section of the 3C-SiC single crystal film obtained in the comparative example. Fig. 12 shows the results of the crystallinity evaluation of the 3C-SiC single crystal film obtained in the comparative example. Figure 13 shows the physical properties of the main semiconductor materials.

1: Single crystal silicon substrate

2: attached carbon

3: SiC single crystal bottom film

4: Amorphous silicon film

5: SiC single crystal film

10: Semiconductor substrate

Claims (11)

A method for manufacturing a semiconductor substrate, for manufacturing a semiconductor substrate with a SiC single crystal film on the surface, is characterized by including the following steps: In the carbon attachment step, carbon is attached to the surface of the single crystal silicon substrate; The step of forming a SiC single crystal underlayer film, carbonizing the surface of the single crystal silicon substrate with the carbon attached to form an SiC single crystal underlayer film; An amorphous silicon film forming step, forming an amorphous silicon film on the SiC single crystal underlayer film; and In the SiC single crystal film growth step, the SiC single crystal underlayer film is used as a seed crystal, and the amorphous silicon film is turned into a SiC single crystal film by solid phase growth. Such as the method of manufacturing a semiconductor substrate of claim 1, wherein: In the carbon adhesion step, the single crystal silicon substrate is subjected to RTA treatment at a temperature of 800° C. or less in a carbon-containing gas environment. Such as the method of manufacturing a semiconductor substrate of claim 1, wherein: In the step of forming the SiC single crystal underlayer film, the single crystal silicon substrate is subjected to an RTA treatment at 1150° C. to 1300° C. in a carbon-containing gas environment to form a SiC single crystal underlayer film with a thickness of 7 nm or less. Such as the method of manufacturing a semiconductor substrate of claim 1, wherein: In the step of forming the amorphous silicon film, an amorphous silicon film having a thickness less than three times the thickness of the SiC single crystal underlayer film is vapor-grown on the SiC single crystal underlayer film at a growth temperature of 300 to 600°C . Such as the method of manufacturing a semiconductor substrate of claim 1, wherein: In the SiC single crystal film growth step, the single crystal silicon substrate is subjected to RTA treatment at 1150°C to 1300°C in a carbon-containing gas environment. Such as the method of manufacturing a semiconductor substrate of claim 1, wherein: The step of forming the amorphous silicon film and the step of growing the SiC single crystal film are repeated twice or more. Such as the method of manufacturing a semiconductor substrate of claim 1, wherein: The SiC single crystal film is formed to be thicker than 15 nm. Such as the method of manufacturing a semiconductor substrate of claim 1, wherein: The SiC single crystal bottom film and the SiC single crystal film are 3C-SiC. A method for manufacturing SOI wafers, which is characterized by: A single crystal silicon substrate with 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 of an SOI wafer to manufacture an SOI wafer. A method for manufacturing a semiconductor substrate, which is characterized in: A single crystal silicon 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. An SOI wafer, which is characterized by: Equipped with a supporting substrate, an insulating layer on the supporting substrate, and an SOI layer on the insulating layer; The supporting substrate is a single crystal silicon substrate; The insulating layer is composed of a 3C-SiC single crystal film.

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