JP5265985B2 - Single crystal deposition method - Google Patents

Description

  The present invention relates to a single crystal film forming method for forming a single crystal thin film on the surface of a crystal substrate to be formed.

  Silicon carbide (SiC) is a semiconductor that has a breakdown electric field strength of about 10 times that of silicon (Si), and also has excellent physical properties in terms of thermal conductivity, electron mobility, band gap, and the like. Therefore, it is expected as a semiconductor material that realizes a dramatic performance improvement as compared with conventional silicon-based power semiconductor elements.

  For this reason, an apparatus for forming a single crystal thin film of silicon carbide (SiC) for semiconductor on the surface of a crystal substrate has been actively developed. For example, Patent Document 1 discloses such an apparatus.

  In such a single crystal film forming apparatus 100, as shown in FIG. 7, a support base (also referred to as a susceptor) 106 fixed on a rotating shaft 104 is arranged in a vertical reactor 102, and the support base is also provided. A heater 110 for heating the crystal substrate 108 via the support base 106 is installed below the 106.

  Further, a reaction gas inlet 114 for supplying a reaction gas 112 obtained by mixing, for example, a silicon (Si) source gas, a carbon (C) source gas, and a carrier gas is formed above the vertical reactor 102, Below the reaction gas introduction port 114, there is provided an exhaust port 116 for making the pressure in the reaction gas introduction port 114 constant or exhausting the unreacted gas out of the reaction gas 112 described above.

  Then, by rotating the support base 106 via the rotating shaft 104, the crystal substrate 108 on the support base 106 is rotated, and at the same time, the interior of the vertical reactor 102 is heated by the heater 110, and the reaction is performed from the reaction gas inlet 114. By supplying the gas 112, a single crystal thin film of silicon carbide (SiC) can be formed on the surface of the crystal substrate.

  By the way, when the reactive gas 112 is sprayed onto the surface of the crystal substrate 108 from directly above the center of the crystal substrate 108, the silicon carbide (SiC) single crystal thin film formed on the crystal substrate 108 is close to the center of the rotation axis 104. It will grow faster. For this reason, in the radial direction of the crystal substrate 108, the growth rate of the single crystal thin film becomes slower from the center to the outer periphery of the crystal substrate 108, and the doping concentration and film thickness of the single crystal thin film may vary. .

  In addition, since the silicon (Si) source gas and the carbon (C) source gas, which are the raw materials of the reaction gas 112, are different in the progress of the decomposition reaction, if there is a temperature distribution inside the vertical reactor 102, the source gas As a result, the concentration ratio of the reactive species may vary in the vertical reactor 102.

  Further, when the large vertical reactor 102 is used with the large-diameter crystal substrate 108, the temperature distribution on the support base 106 becomes remarkable, so that the variation of the reaction species concentration also increases.

Further, since it is known that the point defect density in the single crystal thin film is affected by the growth temperature of the single crystal thin film and the concentration of the carbon (C) raw material, it is considered that the point defect also varies.
In order to eliminate such variation, in Patent Document 2, as shown in FIG. 8, the reaction gas inlet provided at the top of the vertical reactor 202 has a central portion located immediately above the central portion of the crystal substrate 208. The reaction port 212 is composed of two types, that is, an introduction port 214a and an outer peripheral part introduction port 214b located immediately above the outer peripheral part of the crystal substrate 208, and the reaction gas 212 is supplied from each position toward the crystal substrate 208. A single crystal film forming apparatus 200 is disclosed in which the flow rate and concentration of the gas 212 are adjusted and changed via adjusting means 216a and 216b, respectively. Reference numeral 206 in the figure denotes a support base on which the crystal substrate 208 is placed, and reference numeral 204 denotes a rotation shaft for rotating the support base 206.

If such a single crystal film forming apparatus 200 is used, the single crystal thin film formed on the crystal substrate 208 has a uniform doping concentration and film thickness at both the central portion and the outer peripheral portion of the crystal substrate 208. It is possible to form.
JP-A-5-335253 JP 2001-351864 A

  However, in such a single crystal deposition apparatus 200, although the flow rate and concentration of the reaction gas 212 can be adjusted to each, a specific adjustment method is not disclosed, and thus the growth rate variation of the single crystal thin film is not yet disclosed. It was something that could not be surely suppressed.

For this reason, it is required to clarify how the reaction gas is specifically adjusted to form a single crystal thin film having no variation on the crystal substrate.
In view of such a current situation, the present invention provides a doping concentration of a silicon carbide (SiC) single crystal thin film formed on the surface of the crystal substrate in forming a silicon carbide (SiC) single crystal thin film on the surface of the crystal substrate. It is an object of the present invention to provide a single crystal film forming method capable of forming a single crystal thin film with a uniform doping concentration and film thickness without causing variations in film thickness.

The present invention has been invented in order to achieve the problems and objects in the prior art as described above, and the single crystal film forming method of the present invention comprises:
Disposing a crystal substrate on a support provided in a vertical reactor having a space limited inside;
Rotating the support on which the crystal substrate is disposed by power means;
A reaction gas in which a silicon (Si) source gas, a carbon (C) source gas, a dopant gas and a carrier gas are mixed is introduced into the center of the crystal substrate on the support table rotated by the power means from the center introduction port. And, similarly, the step of introducing the reaction gas into the outer peripheral portion of the crystal substrate from the outer peripheral inlet,
Heating the crystal substrate disposed on the support table by heating the support table in the vertical reactor with a heating means;
A step of continuously depositing and growing component elements or compounds of the reaction gas on the heated surface of the crystal substrate, thereby forming a single crystal thin film of silicon carbide (SiC) on the surface of the crystal substrate;
A method of forming a single crystal having at least
In the step of introducing the reaction gas,
The C / Si ratio value of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port is set differently ,
In the step of forming the single crystal thin film,
The single crystal thin film formed on the surface of the crystal substrate has the same C / Si ratio between the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port. When the doping concentration in the outer peripheral part is higher than the central part of the substrate,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set to be larger than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The single crystal thin film formed on the surface of the crystal substrate has the same C / Si ratio between the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port. When the doping concentration in the outer peripheral portion is lower than the central portion of the substrate,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set to be smaller than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. Features.

Thus, if the C / Si ratio is varied and the reaction gas is introduced into the vertical reactor from a plurality of positions, the doping concentration and the film thickness of the single crystal thin film do not vary, and the uniform doping concentration and A SiC single crystal thin film having a thickness can be formed on the surface of the crystal substrate.
Further, the C / Si ratio of the reaction gas introduced from the central part introduction port and the reaction gas introduced from the outer peripheral part introduction port is the same, and the single crystal thin film formed on the surface of the crystal substrate is When the doping concentration in the outer peripheral portion is higher than that in the central portion of the crystal substrate, the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set as the C / S ratio of the reaction gas introduced from the central portion introduction port. If the value is larger than the value of / Si ratio, there is no variation in doping concentration and film thickness on the surface of the crystal substrate, and a single crystal thin film having a uniform thickness can be formed.
Further, in the step of forming the single crystal thin film in this way, the C / Si ratio of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer portion introduction port is the same, and the surface of the crystal substrate In the case where the single crystal thin film formed on the substrate has a lower doping concentration in the outer peripheral portion than in the central portion of the crystal substrate, the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion inlet is If it is smaller than the C / Si ratio of the reaction gas introduced from the introduction port, the single crystal thin film having a uniform thickness can be formed on the surface of the crystal substrate with no variation in doping concentration and film thickness.

In addition, the single crystal film forming method of the present invention includes:
In the step of forming the single crystal thin film,
When setting the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port to be larger than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set within a range of 101% to 1000% of the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. It is characterized by that.

  If the value of the C / Si ratio is set within such a range, a single crystal thin film having a uniform thickness can be formed on the surface of the crystal substrate without variations in doping concentration and film thickness. In this range, it is difficult to form a single crystal thin film particularly when the upper limit is exceeded.

In addition, the single crystal film forming method of the present invention includes:
In the step of forming the single crystal thin film,
When setting the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port to be a value smaller than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set within a range of 5% to 99% of the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. It is characterized by that.

  If the value of the C / Si ratio is set within such a range, a single crystal thin film having a uniform thickness can be formed on the surface of the crystal substrate without variations in doping concentration and film thickness. In this range, if the lower limit is exceeded, it is difficult to form a single crystal thin film.

In addition, the single crystal film forming method of the present invention includes:
Disposing a crystal substrate on a support provided in a vertical reactor having a space limited inside;
Rotating the support on which the crystal substrate is disposed by power means;
A reaction gas in which a silicon (Si) source gas, a carbon (C) source gas, a dopant gas and a carrier gas are mixed is introduced into the center of the crystal substrate on the support table rotated by the power means from the center introduction port. And, similarly, the step of introducing the reaction gas into the outer peripheral portion of the crystal substrate from the outer peripheral inlet,
Heating the crystal substrate disposed on the support table by heating the support table in the vertical reactor with a heating means;
A step of continuously depositing and growing component elements or compounds of the reaction gas on the heated surface of the crystal substrate, thereby forming a single crystal thin film of silicon carbide (SiC) on the surface of the crystal substrate;
A method of forming a single crystal having at least
In the step of introducing the reaction gas,
When hydrogen chloride (HCl) is contained in the carrier gas of the reaction gas and / or chlorine (Cl) is contained in the silicon (Si) source gas,
The Cl / Si ratio values of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer periphery portion introduction port are set differently from each other.

  As described above, the reaction gas containing chlorine (Cl) contributes to the decomposition reaction of the raw material gas, and the decomposition reaction is different from the case of not containing this, resulting in an influence on the film thickness of the single crystal thin film. However, if the value of the Cl / Si ratio is set in this way, variations in the thickness of the single crystal thin film can be prevented.

In addition, the single crystal film forming method of the present invention includes:
In the step of forming the single crystal thin film,
Growth of a single crystal thin film formed on the surface of the crystal substrate with the same Cl / Si ratio value of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port When the outer peripheral part is faster than the central part of the crystal substrate,
The value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port and the value of the Cl / Si ratio of the reaction gas introduced from the central portion introduction port are set to be shifted by 5% or more. Features.

When the value of the Cl / Si ratio is set in this way, a single crystal thin film having a uniform thickness can be formed without variation in the film thickness of the surface of the crystal substrate.
When the silicon (Si) source gas is saturated in the gas phase, the decomposition reaction of the silicon (Si) source gas is promoted by adding a chlorine-based gas to the reaction gas.

For this reason, when the silicon (Si) source gas is saturated in the gas phase, the value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral inlet is set to the value of the reaction gas introduced from the central inlet. By making it smaller than the value of Cl / Si ratio by 5% or more, variations in the film thickness of the single crystal thin film can be prevented.

  On the other hand, when the silicon (Si) source gas is not saturated in the gas phase, adding a chlorine-based gas to the reaction gas increases the etching effect on the surface of the crystal substrate, resulting in the formation of a single crystal thin film. The speed will be slow.

For this reason, when the silicon (Si) source gas is not saturated in the gas phase, the value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral inlet is set to the value of the reaction gas introduced from the central inlet. By making it 5% or more larger than the value of Cl / Si ratio, it is possible to prevent variations in the thickness of the single crystal thin film.

In addition, the single crystal film forming method of the present invention includes:
In the step of forming the single crystal thin film,
Growth of a single crystal thin film formed on the surface of the crystal substrate with the same Cl / Si ratio value of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port When the speed is slower at the outer periphery than the center of the crystal substrate,
The value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port and the value of the Cl / Si ratio of the reaction gas introduced from the central portion introduction port are set to be shifted by 5% or more. Features.

When the value of the Cl / Si ratio is set in this way, a single crystal thin film having a uniform thickness can be formed without variation in the film thickness of the surface of the crystal substrate.
When the silicon (Si) source gas is saturated in the gas phase, the value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral inlet is set to Cl of the reactive gas introduced from the central inlet. /
By making it 5% or more larger than the value of the Si ratio, it is possible to prevent variations in the thickness of the single crystal thin film.

On the other hand, when the silicon (Si) source gas is not saturated in the gas phase, the value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral inlet is set to Cl of the reactive gas introduced from the central inlet.
By making it smaller than the value of the / Si ratio by 5% or more, variations in the thickness of the single crystal thin film can be prevented.

In addition, the single crystal film forming method of the present invention includes:
In the step of introducing the reaction gas,
The C / Si ratio values of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port are set differently from each other.

Thus, if the value of the Cl / Si ratio is set together with the C / Si ratio, it is possible to further prevent variations in the film thickness and doping concentration of the single crystal thin film.
In addition, the single crystal film forming method of the present invention includes:
In the step of introducing the reaction gas,
A center inlet for introducing the reaction gas into the center of the crystal substrate is positioned directly above the center of the crystal substrate,
The outer peripheral inlet for introducing the reaction gas into the outer peripheral portion of the crystal substrate is positioned at a position spaced a predetermined distance from the position of the central inlet toward the outer peripheral direction of the crystal substrate. .

If the central part introduction port and the outer peripheral part introduction port are provided at such positions, variations in the film thickness and doping concentration of the single crystal thin film can be reliably prevented.
In addition, the single crystal film forming method of the present invention includes:
In the step of introducing the reaction gas,
The central part introduction port for introducing the reaction gas into the central part of the crystal substrate is positioned at a predetermined distance from the center part of the crystal substrate toward the outer peripheral direction of the crystal substrate rather than immediately above the central part.
The outer peripheral part introduction port for introducing the reaction gas into the outer peripheral part of the crystal substrate is positioned at a position further away from the position of the central part introduction port by a predetermined distance in the outer peripheral direction of the crystal substrate. To do.

  If the central part introduction port and the outer peripheral part introduction port are provided at such positions, variations in the film thickness and doping concentration of the single crystal thin film can be reliably prevented.

  According to the method of forming a single crystal of the present invention, reaction gases having different C / Si ratios are introduced into the central part of the crystal substrate from the central part inlet and from the outer peripheral part to the outer peripheral part. Therefore, there is no variation in the doping concentration and film thickness of the silicon carbide (SiC) single crystal thin film formed on the surface of the crystal substrate, and the single crystal thin film is formed with a uniform doping concentration and film thickness. be able to.

  Further, when hydrogen chloride (HCl) is contained in the carrier gas of the reaction gas and / or chlorine (Cl) is contained in the silicon (Si) source gas, the value of the Cl / Si ratio is set. If set, variation in doping concentration and film thickness of the single crystal thin film can be prevented.

  Moreover, if the value of the Cl / Si ratio is set simultaneously with the C / Si ratio, variations in the film thickness and doping concentration of the single crystal thin film can be further prevented.

Hereinafter, embodiments (examples) of a single crystal film forming apparatus used in the single crystal film forming method of the present invention will be described in more detail with reference to the drawings.
FIG. 1 is a schematic diagram for explaining one embodiment of a single crystal film forming apparatus used in the single crystal film forming method of the present invention, and FIG. 2 is a top view of the single crystal film forming apparatus shown in FIG. 2 (a) to 2 (c) are explanatory top views for explaining examples of formation of the outer peripheral portion introduction port and the central portion introduction port of the reaction gas introduction port, and FIGS. 3 and 4 show the reaction gas introduction port. FIG. 5 illustrates another embodiment of the single crystal film forming apparatus used in the single crystal film forming method of the present invention. FIG. 6 is a schematic diagram for explaining another embodiment of the single crystal film forming apparatus used in the single crystal film forming method of the present invention.

In the present invention, when a single crystal thin film of silicon carbide (SiC) is formed on the surface of a crystal substrate to be deposited, a single crystal that does not cause variations in doping concentration and film thickness on the surface of the crystal substrate. This is a method for forming a crystalline thin film.
<Single crystal film forming apparatus 10>
First, the single crystal film forming apparatus 10 used in the single crystal film forming method of the present invention will be described.

As shown in FIG. 1, a single crystal film forming apparatus 10 is provided with a vertical reactor 12 having a space limited inside, and the vertical reactor 12 for placing a crystal substrate 18 thereon. A support base (also referred to as a susceptor) 16, power means 14 for rotating the support base 16 via a shaft connected to the support base 16, and silicon (Si) source gas on the crystal substrate 18 on the support base 16 A reaction gas introduction port 20 for introducing a reaction gas 22 in which a carbon (C) source gas, a dopant gas, and a carrier gas are mixed, and the support base 16 are heated to heat the crystal substrate 18 disposed on the support base 16. Heating means (not shown).

In this reaction gas 22, as the silicon (Si) source gas, for example, SiH ₄
SiCl ₄ , SiHCl ₃ , SiH ₂ Cl ₂ , and CH ₃ SiCl ₃ can be used, and for example, C ₃ H ₈ , C ₂ H ₂ , and CH ₃ SiCl ₃ are used as the carbon (C) source gas. it can.

Further, as the dopant gas, for example, N ₂ , (CH ₃ ) ₃ Al can be used,
As the carrier gas, for example, H ₂ and HCl can be used.
In particular, with respect to the reaction gas introduction port 20, the reaction gas 22 is introduced into the central portion of the crystal substrate 18 on the support 16 at the central portion introduction port 20 a for introducing the reaction gas 22 and similarly to the outer peripheral portion of the crystal substrate 18. Two types of introduction ports, the outer periphery introduction port 20b to be introduced, are formed, and the outer periphery introduction port 20b is positioned outside the center introduction port 20a.

  The two types of inlets may have any shape as long as the reactive gas 22 can be introduced into the central portion and the outer peripheral portion of the crystal substrate 18, for example, FIGS. 2 (a) to 2 ( The configuration shown in c) can be adopted.

  In the form shown in FIG. 2A, a central portion introduction port 20 a is formed at a position directly above the center portion of the crystal substrate 18, and a donut-shaped outer periphery portion introduction port 20 b is formed at a position immediately above the outer periphery portion of the crystal substrate 18. doing.

  Next, in the form shown in FIG. 2B, a central part introduction port 20a is formed at a position directly above the central part of the crystal substrate 18, and a shape similar to that of the central part introduction port is formed at a position directly above the outer peripheral part of the crystal substrate 18. A plurality of (four in this figure) outer peripheral portion introduction ports 20b are formed.

  Further, in the embodiment shown in FIG. 2C, a central inlet 20a is formed at a position directly above the central portion of the crystal substrate 18, and a cylindrical outer peripheral inlet 20b is formed at a position immediately above the outer periphery of the crystal substrate 18. Forming.

These forms are preferably selected as appropriate depending on the size of the crystal substrate 18 to be deposited and the deposition conditions.
2A to 2C, the central inlet 20a is located immediately above the central portion of the crystal substrate 18. However, as shown in FIG. The introduction port 20 a may be provided so as to be shifted from the center of the crystal substrate 18 by a predetermined distance L in the outer peripheral direction of the crystal substrate 18. When the central part introduction port 20a is formed at such a position, the outer peripheral part introduction port 20b may be provided further on the outer peripheral direction side of the crystal substrate 18 than the central part introduction port 20a.

  Furthermore, in this embodiment, two types of the central part introduction port 20a and the outer peripheral part introduction port 20b are used, but the number is not particularly limited, and when the crystal substrate 18 is large, as shown in FIG. For example, the first outer peripheral portion introduction port 20b1 and the second outer peripheral portion introduction port 20b2 may be provided at a plurality of concentric positions from the center of the crystal substrate 18.

  In the single crystal film forming apparatus 10 having such a configuration, the reaction gas 22 is separately introduced from each of the above-described central part introduction port 20a and outer peripheral part introduction port 20b. In the film method, the reaction gas 22 is converted into a C / Si ratio value or a Cl / Si ratio value between the reaction gas 22 introduced from the central portion introduction port 20a and the reaction gas 22 introduced from the outer portion introduction port 20b. Thus, a single crystal thin film of silicon carbide (SiC) having a uniform doping concentration and film thickness can be formed on the surface of the crystal substrate 18. ing.

  The single crystal film forming apparatus 10 shown in FIG. 1 has a structure having a certain distance from the lower end portion of the reaction gas inlet 20 to the upper surface of the crystal substrate 18. In some cases, the reaction gas 22 having a different C / Si ratio value or Cl / Si ratio value introduced from each of the part introduction port 20a and the outer periphery introduction port 20b may be mixed.

  In such a case, as shown in FIG. 5, the distance T from the lower end portion to the upper surface of the crystal substrate 18 is shortened by extending the lower end portion of the reaction gas introduction port 20 downward, thereby the center portion introduction port. It is possible to prevent the reaction gases introduced from 20a and the outer peripheral portion introduction port 20b from being mixed.

  The distance T is appropriately changed depending on the size of the crystal substrate 18 and the film forming conditions, and the distance T may be different between the center introduction port 20a and the outer periphery introduction port 20b. It is.

  Furthermore, the single crystal film forming apparatus 10 in the present embodiment is configured such that the reaction gas 22 is introduced from above the crystal substrate 18, and the crystal substrate 18 as shown in FIG. A configuration in which the reaction gas 22 is introduced from below may be employed.

In this case, it is preferable to fix the crystal substrate 18 to the support base 16 with some fixing member (not shown).
<Single crystal deposition method>
Next, a single crystal film forming method using the above-described single crystal film forming apparatus 10 will be described.

In the single crystal film forming method of the present invention, as shown in FIG. 1, first, a crystal substrate 18 is arranged on a support base 16 provided in a vertical reactor 12 having a space limited inside. .
Next, the support 16 on which the crystal substrate 18 is arranged is rotated by the power unit 14.

  At this time, a reaction in which a silicon (Si) source gas, a carbon (C) source gas, and a carrier gas are mixed from the center introduction port 20a at the center of the crystal substrate 18 on the support 16 rotated by the power means 14. The gas 22 is introduced, and similarly, the reaction gas 22 in which the silicon (Si) source gas, the carbon (C) source gas, and the carrier gas are mixed is introduced into the outer peripheral portion of the crystal substrate 18 from the outer peripheral inlet 20b. .

And the crystal substrate 18 arrange | positioned at the support stand 16 is heated by heating the support stand 16 in the vertical reactor 12 with a heating means (not shown).
Then, component elements or compounds of the reaction gas 22 are continuously deposited and grown on the surface of the heated crystal substrate 18, thereby forming a single crystal thin film of silicon carbide (SiC) on the surface of the crystal substrate 18. It becomes.

  In the single crystal film forming method of the present invention, when the reaction gas 22 is introduced, the C / Si of the reaction gas 22 introduced from the central inlet 20a and the reaction gas 22 introduced from the outer peripheral inlet 20b. The ratio is made different for each.

  Specifically, the reaction gas 22 introduced from the central part introduction port 20a and the reaction gas 22 introduced from the outer peripheral part introduction port 20b have the same C / Si ratio, and a single film formed on the surface of the crystal substrate 18 is formed. When the crystalline thin film has a higher doping concentration in the outer peripheral portion than in the central portion of the crystal substrate 18, the value of the C / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b is determined as the central inlet 20a. It is preferable to set a value larger than the value of the C / Si ratio of the reaction gas 22 introduced more.

  The value of the C / Si ratio of the reaction gas introduced from the outer peripheral inlet 20b is set to be larger than the value of the C / Si ratio of the reaction gas 22 introduced from the central inlet 20a. In this case, the value of the C / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b is 101% to 1000% of the value of the C / Si ratio of the reaction gas 22 introduced from the central inlet 20a. It is preferably set within the range, more preferably set within the range of 105% to 500%, and even more preferably set within the range of 110% to 300%.

  On the other hand, the C / Si ratio of the reaction gas 22 introduced from the center introduction port 20a and the reaction gas 22 introduced from the outer periphery introduction port 20b is the same, and the film is formed on the surface of the crystal substrate 18. When the doped single crystal thin film has a lower doping concentration in the outer peripheral portion than in the central portion of the crystal substrate 18, the value of the C / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20 b is set at the central portion. It is preferable to set the value to be smaller than the value of the C / Si ratio of the reaction gas 22 introduced from the introduction port 20a.

  Note that the value of the C / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b is set to be smaller than the value of the C / Si ratio of the reaction gas 22 introduced from the central inlet 20a. When setting, the value of the C / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b is set to 5% to 99% of the value of the C / Si ratio of the reaction gas 22 introduced from the central inlet 20a. Is preferably set in the range of 20% to 95%, more preferably in the range of 30% to 90%.

  As described above, the reaction gas 22 introduced into each of the central inlet 20a and the outer peripheral inlet 20b in accordance with the film formation state of the single crystal thin film has a different C / Si ratio. By setting the value in the above-described range, a silicon carbide (SiC) single crystal thin film having a uniform doping concentration and film thickness can be reliably formed on the surface of the crystal substrate 18.

  In addition, in the method of forming a single crystal according to the present invention, when the reaction gas 22 is introduced, the carrier gas of the reaction gas 22 contains hydrogen chloride (HCl) or the silicon (Si) source gas contains chlorine ( When Cl) is contained, the Cl / Si ratio values of the reaction gas 22 introduced from the central portion introduction port 20a and the reaction gas 22 introduced from the outer peripheral portion introduction port 20b are also made different from each other. I have to.

Specifically, the reaction gas 22 introduced from the central part introduction port 20a and the reaction gas 22 introduced from the outer peripheral part introduction port 20b have the same Cl / Si ratio, and are formed on the surface of the crystal substrate 18. When the growth rate of the single crystal thin film is higher in the outer peripheral portion than in the central portion of the crystal substrate 18, the value of the Cl / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b and the center Department entrance 2
The value of the Cl / Si ratio of the reaction gas 22 introduced from 0a is preferably set to be shifted by 5% or more.

When the value of the Cl / Si ratio is set in this way, a single crystal thin film having a uniform thickness can be formed on the surface of the crystal substrate 18 without variation in film thickness.
Note that the influence of the addition of the chlorine-based gas on the deposition rate of the single crystal thin film differs depending on whether the silicon (Si) source gas is saturated in the gas phase.

  First, when the silicon (Si) source gas is saturated in the gas phase, the decomposition reaction of the silicon (Si) source gas is promoted by adding a chlorine-based gas to the reaction gas 22.

Therefore, when the silicon (Si) source gas is saturated in the gas phase, the value of the Cl / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b is introduced from the central inlet 20a. By reducing the Cl / Si ratio of the reaction gas 22 by 5% or more, variations in the thickness of the single crystal thin film can be prevented.

  On the other hand, when the silicon (Si) source gas is not saturated in the gas phase, adding a chlorine-based gas to the reaction gas 22 increases the etching effect on the surface of the crystal substrate 18, resulting in a single crystal thin film. The film forming speed will be slow.

For this reason, when the silicon (Si) source gas is not saturated in the gas phase, the Cl / Si ratio value of the reaction gas 22 introduced from the outer peripheral inlet 20b is introduced from the central inlet 20a. By making the Cl / Si ratio of the reaction gas 22 greater than 5% or more, variations in the thickness of the single crystal thin film can be prevented.

On the other hand, the reaction gas 22 introduced from the central part introduction port 20a and the reaction gas 22 introduced from the outer peripheral part introduction port 20b have the same Cl / Si ratio and are formed on the surface of the crystal substrate 18. When the growth rate of the single crystal thin film is slower in the outer peripheral part than in the central part of the crystal substrate 18, the value of the Cl / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20 b and the central part Inlet 2
The value of the Cl / Si ratio of the reaction gas 22 introduced from 0a is preferably set to be shifted by 5% or more.

When the value of the Cl / Si ratio is set in this way, a single crystal thin film having a uniform thickness can be formed on the surface of the crystal substrate 18 without variation in film thickness.
When the silicon (Si) source gas is saturated in the gas phase, the value of the Cl / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b is used as the reaction introduced from the central inlet 20a. By making the Cl / Si ratio of the gas 22 larger by 5% or more, it is possible to prevent variations in the thickness of the single crystal thin film.

On the other hand, when the silicon (Si) source gas is not saturated in the gas phase, the value of the Cl / Si ratio of the reaction gas 22 introduced from the outer peripheral inlet 20b is set to the reaction introduced from the central inlet 20a. By making the Cl / Si ratio of the gas 22 smaller by 5% or more, variations in the thickness of the single crystal thin film can be prevented.

  Although the single crystal film forming method of the present invention has been described above, the present invention is not limited to these embodiments. For example, as shown in FIG. When there are many 20b, the setting range of the value of the C / Si ratio and the value of the Cl / Si ratio may be determined each time.

  Furthermore, according to the single crystal film forming method of the present invention, the value of the C / Si ratio between the reaction gas 22 introduced from the central portion introduction port 20a and the reaction gas 22 introduced from the outer peripheral portion introduction port 20b and the Cl / Si By setting the ratio value as described above, the doping concentration and film thickness of the single crystal thin film do not vary. However, even if these are set separately, two values are set simultaneously. You can do it. When two are set at the same time, it is possible to further prevent variations in the film thickness and doping concentration of the single crystal thin film than when only one is set.

In addition to the above-mentioned C / Si ratio value and Cl / Si ratio value, the carrier gas flow rate ratio, source gas flow rate ratio, dopant gas flow rate, HCl flow rate, etc. are set separately for each gas inlet. In this way, the single crystal thin film does not vary in doping concentration and film thickness more accurately than when only the C / Si ratio value and Cl / Si ratio value are set. Various settings can be added without departing from the scope of the invention.

FIG. 1 is a schematic diagram for explaining one embodiment of a single crystal film forming apparatus used in the single crystal film forming method of the present invention. 2 is a top view of the single-crystal film forming apparatus shown in FIG. 1, and FIGS. 2A to 2C show the outer peripheral inlet 20b and the central inlet 20a of the reactive gas 22 inlet. It is an explanatory top view explaining the example of formation of. FIG. 3 is an explanatory top view illustrating another example of forming the outer peripheral portion introduction port 20b and the central portion introduction port 20a of the reaction gas 22 introduction port. FIG. 4 is an explanatory top view illustrating another example of forming the outer peripheral portion introduction port 20b and the central portion introduction port 20a of the reaction gas 22 introduction port. FIG. 5 is a schematic diagram for explaining another embodiment of the single crystal film forming apparatus used in the single crystal film forming method of the present invention. FIG. 6 is a schematic diagram for explaining another embodiment of the single crystal film forming apparatus used in the single crystal film forming method of the present invention. FIG. 7 is a schematic view for explaining a conventional single crystal film forming apparatus. FIG. 8 is a schematic view for explaining a conventional single crystal film forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Single-crystal film-forming apparatus 12 ... Vertical reactor 14 ... Power means 16 ... Support stand (susceptor)
18 ... Crystal substrate 18
20... Reaction gas 22 inlet 20a .. Central part inlet 20a
20b..Outer peripheral inlet 20b
20b1 and first outer peripheral inlet 20b
20b2 · second outer peripheral inlet 20b
22 ... Reaction gas 22
DESCRIPTION OF SYMBOLS 100 ... Single-crystal film-forming apparatus 102 ... Vertical reactor 104 ... Rotating shaft 106 ... Support stand (susceptor)
108: Crystal substrate 18
110 ... heater 112 ... reactive gas 22
114 ... reaction gas 22 inlet 116 ... exhaust port 200 ... single crystal film forming apparatus 202 ... vertical reactor 204 ... rotary shaft 206 ... support (susceptor)
208 ... Crystal substrate 18
212 ... Reaction gas 22
214a ... Central part inlet 20a
214b..Outer peripheral inlet 20b
216a ... Adjusting means 216b ... Adjusting means

Claims (13)

Disposing a crystal substrate on a support provided in a vertical reactor having a space limited inside;
Rotating the support on which the crystal substrate is disposed by power means;
A reaction gas in which a silicon (Si) source gas, a carbon (C) source gas, a dopant gas and a carrier gas are mixed is introduced into the center of the crystal substrate on the support table rotated by the power means from the center introduction port. And, similarly, the step of introducing the reaction gas into the outer peripheral portion of the crystal substrate from the outer peripheral inlet,
Heating the crystal substrate disposed on the support table by heating the support table in the vertical reactor with a heating means;
A step of continuously depositing and growing component elements or compounds of the reaction gas on the heated surface of the crystal substrate, thereby forming a single crystal thin film of silicon carbide (SiC) on the surface of the crystal substrate;
A method of forming a single crystal having at least
In the step of introducing the reaction gas,
The C / Si ratio value of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port is set differently ,
In the step of forming the single crystal thin film,
The single crystal thin film formed on the surface of the crystal substrate has the same C / Si ratio between the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port. When the doping concentration in the outer peripheral part is higher than the central part of the substrate,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set to be larger than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The single crystal thin film formed on the surface of the crystal substrate has the same C / Si ratio between the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port. When the doping concentration in the outer peripheral portion is lower than the central portion of the substrate,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set to be smaller than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. A single crystal film forming method characterized. In the step of forming the single crystal thin film,
When setting the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port to be larger than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set within a range of 101% to 1000% of the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. The method for forming a single crystal according to claim 1 . In the step of forming the single crystal thin film,
When setting the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port to be a value smaller than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set within a range of 5% to 99% of the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. The method for forming a single crystal according to claim 1 . Disposing a crystal substrate on a support provided in a vertical reactor having a space limited inside;
Rotating the support on which the crystal substrate is disposed by power means;
A reaction gas in which a silicon (Si) source gas, a carbon (C) source gas, a dopant gas and a carrier gas are mixed is introduced into the center of the crystal substrate on the support table rotated by the power means from the center introduction port. And, similarly, the step of introducing the reaction gas into the outer peripheral portion of the crystal substrate from the outer peripheral inlet,
Heating the crystal substrate disposed on the support table by heating the support table in the vertical reactor with a heating means;
A step of continuously depositing and growing component elements or compounds of the reaction gas on the heated surface of the crystal substrate, thereby forming a single crystal thin film of silicon carbide (SiC) on the surface of the crystal substrate;
A method of forming a single crystal having at least
In the step of introducing the reaction gas,
When hydrogen chloride (HCl) is contained in the carrier gas of the reaction gas and / or chlorine (Cl) is contained in the silicon (Si) source gas,
A single-crystal film forming method, wherein a value of Cl / Si ratio of a reaction gas introduced from the central portion introduction port and a reaction gas introduced from the outer periphery portion introduction port are set differently. In the step of forming the single crystal thin film,
Growth of a single crystal thin film formed on the surface of the crystal substrate with the same Cl / Si ratio value of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port When the outer peripheral part is faster than the central part of the crystal substrate,
The value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port and the value of the Cl / Si ratio of the reaction gas introduced from the central portion introduction port are set to be shifted by 5% or more. The method for forming a single crystal according to claim 4 , wherein In the step of forming the single crystal thin film,
Growth of a single crystal thin film formed on the surface of the crystal substrate with the same Cl / Si ratio value of the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port When the speed is slower at the outer periphery than the center of the crystal substrate,
The value of the Cl / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port and the value of the Cl / Si ratio of the reaction gas introduced from the central portion introduction port are set to be shifted by 5% or more. The method for forming a single crystal according to claim 4 , wherein In the step of introducing the reaction gas,
The value of the C / Si ratio of the reaction gas introduced from the reactive gas the outer peripheral portion inlet is introduced from the central inlet claim 4, characterized in that to set different for each 6 The single-crystal film-forming method in any one. In the step of forming the single crystal thin film,
The single crystal thin film formed on the surface of the crystal substrate has the same C / Si ratio between the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port. When the doping concentration in the outer peripheral part is higher than the central part of the substrate,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set to be larger than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. The single crystal film forming method according to claim 7 , wherein In the step of forming the single crystal thin film,
When setting the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port to be larger than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set within a range of 101% to 1000% of the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. The single crystal film forming method according to claim 8 . In the step of forming the single crystal thin film,
The single crystal thin film formed on the surface of the crystal substrate has the same C / Si ratio between the reaction gas introduced from the central portion introduction port and the reaction gas introduced from the outer peripheral portion introduction port. When the doping concentration in the outer peripheral portion is lower than the central portion of the substrate,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set to be smaller than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. The single crystal film forming method according to claim 7 , wherein In the step of forming the single crystal thin film,
When setting the value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port to be a value smaller than the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port,
The value of the C / Si ratio of the reaction gas introduced from the outer peripheral portion introduction port is set within a range of 5% to 99% of the value of the C / Si ratio of the reaction gas introduced from the central portion introduction port. The single-crystal film-forming method according to claim 10 . In the step of introducing the reaction gas,
A center inlet for introducing the reaction gas into the center of the crystal substrate is positioned directly above the center of the crystal substrate,
The outer peripheral inlet for introducing the reaction gas into the outer peripheral portion of the crystal substrate is positioned at a position spaced a predetermined distance from the position of the central inlet toward the outer peripheral direction of the crystal substrate. single crystal film forming method according to any one of claims 1 to 11. In the step of introducing the reaction gas,
The central part introduction port for introducing the reaction gas into the central part of the crystal substrate is positioned at a predetermined distance from the center part of the crystal substrate toward the outer peripheral direction of the crystal substrate rather than immediately above the central part.
The outer peripheral part introduction port for introducing the reaction gas into the outer peripheral part of the crystal substrate is positioned at a position further away from the position of the central part introduction port by a predetermined distance in the outer peripheral direction of the crystal substrate. single crystal film deposition method according to any one of claims 1 to 11,.

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