JP6641670B2 - Single wafer type epitaxial wafer manufacturing apparatus and epitaxial wafer manufacturing method - Google Patents

Description

  The present invention relates to a single wafer type epitaxial wafer manufacturing apparatus and an epitaxial wafer manufacturing method using the same.

  In recent years, the demand for high flatness epitaxial wafers from device manufacturers has increased, and improving the flatness quality of epitaxial wafers has become an important issue. In particular, the required quality of flatness in the outer peripheral portion of the epitaxial wafer is high, and it is necessary to strictly control various parameters in the manufacturing process in order to satisfy the requirement. One of the parameters for controlling the outer peripheral flatness is a displacement amount between the center of the susceptor and the center of the wafer when the wafer is placed on the susceptor, that is, a displacement amount. When there is no displacement and the wafer is placed in the center of the wafer pocket provided on the upper surface of the susceptor, the reaction gas during the epitaxial reaction equally hits the entire outer peripheral portion of the wafer. On the other hand, if the wafer is placed out of the center of the wafer pocket, the outer periphery of the wafer, in the portion close to the outer periphery of the wafer pocket, is difficult for the reactive gas to hit the outermost periphery. Thickness sag occurs at the outer peripheral portion. Conversely, in a portion of the outer peripheral portion of the wafer away from the outer peripheral portion of the wafer pocket, the outermost outer periphery is positively exposed to the reaction gas, so that the film thickness flies. In particular, when the outer peripheral portion of the wafer away from the outer peripheral portion of the wafer pocket corresponds to a facet position caused by epitaxial growth, the outer peripheral splash becomes more apparent due to the overlap of the outer peripheral splash due to the mounting displacement and the splash due to the facet growth, Deterioration of outer peripheral flatness becomes remarkable. Therefore, it is important to suppress the variation in the placement of the wafer and control the placement position in order to improve the outer flatness of the epi-wafer.

  One of the causes of the displacement is that when the wafer is loaded into the reactor, the susceptor thermally expands and contracts due to changes in the furnace temperature, and the susceptor position changes for each loaded wafer. Is mentioned. FIG. 6 shows a schematic diagram of a conventional susceptor support portion. As shown in FIG. 6, an arm portion 31 of the support shaft is provided below the susceptor 30. The chip 34 constituting the head of the arm 31 fits into the susceptor recess 32 provided on the lower surface of the susceptor 30 to support the susceptor 30. At this time, a clearance is provided between the susceptor recess 32 and the chip 34. With this clearance, when the susceptor 30 thermally expands, the chip 34 is designed not to receive excessive stress from the susceptor 30 and to release the stress due to the thermal expansion. The large fluctuation of the susceptor 30 and the unstable position of the susceptor 30 is one of the causes of the variation of the wafer mounting position.

  Patent Literatures 1 and 2 disclose a countermeasure for variations in a wafer mounting position. Specifically, Patent Literature 1 discloses that the head of the arm portion is made of quartz, and the quartz head and the susceptor recess are closely fitted together with no play space. Patent Document 2 discloses that a center support member for supporting a central portion of a susceptor is provided, and the center support member is made of SiC or a carbon base material is coated with SiC.

JP 2014-138056 A JP 2013-175543 A

  As described above, in the configuration of Patent Literature 1, it is necessary to change the material of the head of the arm to quartz. Further, in the configuration of Patent Document 2, it is necessary to provide a center support member that supports the center of the susceptor.

  The present invention suppresses variations in the wafer mounting position without changing the material of the head of the arm and installing the center support member, and the arm is damaged due to the stress caused by thermal deformation of the susceptor. It is an object of the present invention to provide a single-wafer-type epitaxial wafer manufacturing apparatus and an epitaxial wafer manufacturing method that can achieve both of suppressing the occurrence of the epitaxial wafer.

In order to solve the above problems, a single wafer type epitaxial wafer manufacturing apparatus of the present invention is
A susceptor provided with a wafer pocket for mounting a wafer on the upper surface,
A support shaft for supporting and rotating the susceptor,
The support shaft has a rotatable main support provided in a vertical direction, and a plurality of arms provided on the main support and supporting a lower surface of the susceptor,
A plurality of susceptor recesses are formed on the lower surface of the susceptor,
The arm portion has an extending portion that extends obliquely upward or horizontally from the main support, and a head that fits into the susceptor recess,
The head is closely fitted to the susceptor recess with a clearance of 0 to 0.5 mm,
The bending rigidity of the extending portion is set to 36 N · m ² or less.

According to the present invention, since the head of the arm is closely fitted to the susceptor recess with a clearance of 0 to 0.5 mm, the head of the arm has a play space in the susceptor recess (0. Thermal deformation of the susceptor can be suppressed as compared with a configuration in which the susceptor is fitted with a clearance larger than 5 mm. Thereby, variation in the wafer mounting position can be suppressed. Furthermore, in the present invention, since the bending rigidity of the extending portion of the arm portion is set to 36 N · m ² or less, the stress caused by the susceptor being thermally deformed can be reduced by the bending of the extending portion. Thereby, stress applied to the periphery of the head can be reduced, and damage to the periphery of the head can be suppressed.

  In addition, as shown in FIG. 8, the clearance is the widest clearance when the head becomes wider when the head 26 of the arm moves inside the susceptor recess 13. A clearance of 0 mm means that the shape of the head 26 of the arm and the susceptor recess 13 completely match, and there is no gap in which the head 26 of the arm moves inside the susceptor recess 13.

Further, in the present invention, the bending rigidity of the extension portion is set to 3 N · m ² or more. By setting the bending rigidity of the extension portion to 3 N · m ² or more, it is possible to prevent the arm portion from sagging from the design position, that is, to suppress a decrease in the durability of the arm portion.

Further, in the present invention, the arm portion includes a chip constituting the head, and an arm main body including the extending portion and having the tip connected to the tip. As described above, if the head (chip) of the arm portion is formed of a separate component, stress is concentrated on the contact portion between the chip and the arm body, and the contact portion is easily damaged. By setting the bending rigidity range of the extension portion to 3 to 36 N · m ² , damage to the contact portion can be suppressed.

  Further, an epitaxial wafer is manufactured by using the single wafer type epitaxial wafer manufacturing apparatus of the present invention. Thereby, the epitaxial wafer can be manufactured in a form in which the variation of the wafer mounting position is suppressed, so that the flatness at the outer peripheral portion of the epitaxial wafer can be improved.

It is a schematic sectional drawing of a single-wafer type epitaxial wafer growth apparatus. It is a schematic diagram in the susceptor support part of the present invention. It is the figure which looked at a susceptor crevice and a chip main part by plane view. FIG. 4 is a sectional view taken along line IV-IV of FIG. 2. It is the figure which looked at the arm main body from the side view. It is a schematic diagram in the conventional susceptor support part. FIG. 9 is a plan view of the chip and the susceptor recess used in Comparative Example 3, and is a diagram illustrating a clearance between the chip and the susceptor recess. It is the figure which looked at a susceptor crevice and a chip main part by plane view, and is a figure explaining how to ask for clearance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The single-wafer-type epitaxial wafer growing apparatus 1 of FIG. 1 includes a reaction furnace 2 formed of a transparent quartz member or the like. A susceptor 14 for placing a wafer W to be epitaxially grown is arranged in the reactor 2. The susceptor 14 is made of, for example, SiC or a graphite base material coated with SiC. The susceptor 14 is formed in a shape having a circular upper surface 14a and a lower surface 14b, that is, in a disk shape. The susceptor 14 is arranged so that the upper surface 14a and the lower surface 14b are horizontal.

  At the center of the upper surface 14a of the susceptor 14, a wafer pocket 12 for horizontally mounting the wafer W is formed. The wafer pocket 12 is formed in a concave shape in side view, and is formed in a circular shape having a diameter slightly larger than the diameter of the wafer W in plan view. The depth of the wafer pocket 12 is substantially equal to the thickness of the wafer W.

  At the bottom of the wafer pocket 12, a plurality of through holes 15 penetrating to the lower surface 14b of the susceptor 14 are formed. Lift pins 29 for accommodating the wafer W in the wafer pocket 12 and removing the wafer W from the wafer pocket 12 are inserted into these through holes 15. The lift pins 29 are provided so as to be able to move up and down. When the lift pins 29 rise, the wafer W is lifted from the wafer pocket 12, and when the lift pins 29 are lowered, the wafer W is housed in the wafer pocket 12.

  Further, a plurality of susceptor recesses 13 into which a chip 22 described later is fitted are formed in an outer peripheral portion of the lower surface 14b of the susceptor 14 (a position radially outward from a central portion of the susceptor where the wafer pocket 12 is formed). The susceptor concave portions 13 are formed by the number of the arm portions 20 and are equally spaced on the circumference around the center line L1 of the susceptor 14 (in other words, the same interval as the interval between the plurality of arm portions 20 in the circumferential direction). It is formed with.

  A support shaft 16 that horizontally supports the susceptor 14 is disposed in a lower region of the susceptor 14. The support shaft 16 includes a main support 18 extending in a vertical direction (a direction parallel to the vertical direction), and a plurality of (for example, three) arm portions 20 extending obliquely upward from an upper portion of the main support 18. Have. The main support 18 is provided such that its center line L2 coincides with the center line L1 of the susceptor 14. The main support 18 is provided rotatably about the center line L2. A space is formed between the upper end 18a of the main support 18 and the lower surface 14b of the susceptor 14.

  The plurality of arms 20 are arranged at equal intervals in the circumferential direction around the main support 18. Each arm unit 20 includes an arm main body 21 connected to the main support 18 and a chip 22 connected to a tip of the arm main body 21 and constituting a head of the arm unit 20. Further, the arm main body 21 includes an inclined portion 23 extending obliquely upward from the main support 18 to a radial position where the susceptor recess 13 is formed, and an end of the inclined portion 23 connected to the main support 18. And a vertical portion 24 extending vertically upward from the opposite end (see FIG. 2). The inclined portion 23 extends linearly. A hole 25 for fixing the chip 22 is formed in the center of the distal end surface of the vertical portion 24. The arm body 21 can be made of, for example, quartz. The inclined portion 23 corresponds to the extension of the present invention. Note that, instead of the inclined portion 23, a horizontal extension portion extending in the horizontal direction may be provided.

  As shown in FIG. 2, the chip 22 has a chip body 26 and a protrusion 27 projecting from the lower surface of the chip body 26. The protrusion 27 has the same diameter as the hole 25 formed in the arm body 21 and is press-fitted or screw-fitted into the hole 25. A part of the chip body 26 from the tip is fitted into the susceptor recess 13. The diameter of the chip body 26 is smaller than, for example, the diameter of the vertical portion 24, and the entire lower surface of the chip body 26 is in contact with the distal end surface of the vertical portion 24. The chip 22 can be made of, for example, SiC.

  Returning to the description of FIG. 1, the inside of the reaction furnace 2 is heated to a predetermined temperature by heating the inside of the reaction furnace 2 during various processes such as vapor phase growth and cleaning of the reaction furnace with hydrogen chloride gas. Is provided. The heater 3 is, for example, a halogen lamp or an infrared lamp.

  At one end of the reactor 2 in the horizontal direction, a gas inlet 5 for introducing various gases into the reactor 2 in the horizontal direction is formed. The gas inlet 5 is formed above the susceptor 14. From the gas inlet 5, a silicon source gas (specifically, a silane-based gas such as trichlorosilane (TCS)) or a silicon source gas as a raw material of a silicon single crystal thin film (silicon epitaxial layer) is diluted during vapor phase growth. A reaction gas containing a carrier gas (for example, hydrogen) for controlling the conductivity type and a dopant gas (for example, a gas containing boron or phosphorus) for adjusting the conductivity type or conductivity of the epitaxial layer is introduced. When the reactor 2 is cleaned, a gas such as a hydrogen chloride gas (HCl) is used as a gas for etching by-products deposited on the inner wall of the reactor 2, the susceptor 14, and the like, instead of the reaction gas, from the gas inlet port 5. Gas) is introduced.

  A gas outlet 6 for discharging gas from the inside of the reaction furnace 2 is formed on a side of the reaction furnace 2 opposite to a side where the gas introduction port 5 is formed.

  Further, the epitaxial wafer growth apparatus 1 includes a driving unit 4 for rotating the main support 18. When the main support 18 is rotated by the drive unit 4, the susceptor 14 and the wafer W mounted thereon rotate around the center line L <b> 1 of the susceptor 14.

  The above is the configuration of the epitaxial wafer growth apparatus 1. The clearance between the tip 22 and the susceptor recess 13 and the range of the bending rigidity of the arm 20 will be described later.

  Next, a method of manufacturing a silicon epitaxial wafer using the epitaxial wafer growth apparatus 1 will be described. First, a silicon wafer W is charged into the reaction furnace 2 and placed in the wafer pocket 12. Hydrogen is introduced into the reactor 2 via the gas inlet 5 from the stage before the silicon wafer W is charged. Next, the silicon wafer W mounted on the susceptor 14 is heated by the heater 3 to a heat treatment temperature (for example, 1050 to 1200 ° C.). Next, gas phase etching for removing a natural oxide film formed on the main surface of the silicon wafer W is performed. Next, the silicon wafer W is adjusted to a desired growth temperature (for example, 1050 to 1180 ° C.), and a reaction gas is introduced from the gas inlet 5 to vapor-grow a silicon single crystal thin film on the main surface of the silicon wafer W. To form a silicon epitaxial wafer. Finally, the reactor 2 is taken out, and the temperature is lowered to a temperature (for example, 650 ° C.), and then the silicon epitaxial wafer is carried out of the reactor 2.

  Here, the wafer W is preferably placed in the wafer pocket 12 such that the center of the wafer coincides with the center of the wafer pocket 12 (the center line L1 of the susceptor 14). If the center of the wafer deviates from the center of the wafer pocket 12, the gap between the outer peripheral portion of the wafer and the outer peripheral portion of the wafer pocket 12 will be deviated, and the deviation will affect how the reaction gas hits the outer peripheral portion of the wafer. This is because the thickness of the epitaxial layer in the outer peripheral portion of the wafer becomes uneven. On the other hand, the susceptor 14 receives a large temperature change between the time when the wafer W is loaded into the reactor 2 and the time when the vapor phase is grown, and the temperature change causes the susceptor 14 to thermally expand or contract. When the wafer pocket 12 expands or contracts in the radial direction due to the thermal deformation (thermal expansion or thermal contraction) of the susceptor 14, the wafer mounting position in the wafer pocket 12 varies.

  Therefore, in the present embodiment, the shape of the chip 22 is matched with the shape of the susceptor recess 13 for the purpose of stabilizing the susceptor position when the wafer is loaded into the reaction furnace 2 and suppressing variation in the mounting position. Conventionally, the clearance between the susceptor recess and the chip has been eliminated. That is, as shown in FIG. 3, the chip body 26 and the susceptor recess 13 are formed in the same shape (a long hole in the example of FIG. 3) in plan view. The clearance between the chip body 26 and the susceptor recess 13 (see FIG. 8) is set to 0 mm. The chip main body 26 is closely fitted to the susceptor recess 13. In consideration of the tolerance of the chip body 26 and the tolerance of the susceptor recess 13, the clearance may be in the range of 0 mm to 0.5 mm. That is, when the design shape of the susceptor recess 13 and the design shape of the chip body 26 become the maximum within the tolerance and the minimum within the tolerance, in the susceptor recess 13 and the chip body 26 actually used, FIG. As shown in FIG. 8, when the tip body 26 moved inside the susceptor recess 13, the clearance was 0.5 mm when the clearance became the widest. Thus, the clearance is set to 0 mm as a value when there is no tolerance, and up to 0.5 mm is allowed when including the tolerance.

  On the other hand, if the clearance is 0 mm to 0.5 mm, there is a possibility that the arm 20 (particularly, the contact portion A between the chip main body 26 and the vertical portion 24 (see FIG. 2)) may be damaged by stress generated by thermal deformation of the susceptor 14. is there.

  Therefore, in the present embodiment, as described below, the thickness of the inclined portion 23 (see FIG. 2) is reduced, and the stress is absorbed by utilizing the bending of the inclined portion 23.

That is, as an index indicating the difficulty of deformation of the beam member with respect to the bending moment, a second moment of area is given. Assuming that the cross section of the inclined portion 23 is, for example, a rectangle, when the cross section dimensions and coordinate axes are defined as shown in FIG. 4 in the rectangular cross section, the second moment of area Ix around the X axis is expressed by the following equation.
Ix ⁼ bh 3/12

Further, as an index indicating the difficulty of bending deformation in consideration of the material of the beam member, there is a bending rigidity J. The bending stiffness J is expressed by the following equation using the Young's modulus E and the second moment of area I.
J = EI

If the material of the inclined portion 23 is quartz, the Young's modulus of the quartz is about E = 7.0 × 10 ^{10 to} 7.4 × 10 ¹⁰ N / m ² .

By setting the bending rigidity J of the inclined portion 23 to 36 N · m ² or less, it is possible to prevent the contact portion A between the chip body 26 and the vertical portion 24 from being damaged. Strictly speaking, when the susceptor 14 is thermally deformed in the radial direction, a force is generated to bend the inclined portion 23 around a direction 100 perpendicular to the plane of FIG. By setting the bending rigidity of the inclined portion 23 around the direction 100 to 36 N · m ² or less, the bending deformation of the inclined portion 23 around the direction 100 can be promoted, whereby the stress applied to the contact portion A can be reduced, The breakage of the contact portion A can be suppressed. The direction 100 is a cross-section when the inclined portion 23 is cut by a plane that includes the center line L3 (see FIG. 2) of the inclined portion 23 in a plane and is parallel to the vertical direction (that is, FIG. 1 and FIG. 2). (Cross-section) and intersects the center line L3. The bending stiffness around a coordinate axis other than the coordinate axis 100 (for example, the coordinate axis 101 set in the plane of the cross section of FIG. 2 and the coordinate axis 102 orthogonal to both the coordinate axes 100 and 101) is: may be greater than 36N · ^{m 2,} may be 36N · ^{m 2} or less, but can be suppressed more, breakage of the contact portion a by a 36N · ^{m 2} or less.

In the example of FIG. 4, when the X axis is the coordinate axis 100 in FIG. 2 and the Y axis is the coordinate axis 102 in FIG. 2, at least the bending stiffness J around the X axis is set to 36 N · m ² or less.

Further, the bending rigidity J of the inclined portion 23 is set to 3 N · m ² or more. If the bending stiffness is less than 3 N · m ² , sagging from the design position occurs in the arm 20 after the epitaxial wafer is manufactured, and the durability of the arm 20 decreases. That is, by setting the bending stiffness J to 3 N · m ² or more, sagging of the arm portion 20 can be suppressed. Incidentally, the bending rigidity of about axes 100 in FIG. 2 is set to 3N · ^{m 2} or more, the bending rigidity of about axes 101, 102 the other is also set to 3N · ^{m 2} or more.

  In the present embodiment, the chip 22 is closely fitted to the susceptor recess 13 with a clearance of 0 to 0.5 mm, so that the thermal deformation of the susceptor 14 causes the susceptor 14 to be displaced within the excessive clearance of the fitting portion. Can be suppressed, and variations in the wafer mounting position can be suppressed. Thereby, the flatness in the outer peripheral portion of the epitaxial wafer can be improved.

In addition, since the bending rigidity range of the inclined portion 23 is set to 3 to 36 N · m ² , the stress generated by the thermal deformation of the susceptor 14 can be reduced by the deflection of the inclined portion 23, and thus, the damage of the arm portion 20 can be suppressed. Also, sagging of the arm portion 20 from the design position can be suppressed.

  FIG. 3 shows an example in which the shapes of the susceptor recess 13 and the chip main body 26 are elongated holes. However, if the clearance satisfies 0 to 0.5 mm, shapes other than the elongated holes (circular, square, etc.) It may be. Further, the material of the arm body 21 may be a material other than quartz. The material of the chip 22 may be other than SiC.

  The cross section of the inclined portion 23 (cross section taken along line IV-IV in FIG. 2) may be a shape other than a rectangle (square, circular, etc.).

  In addition, the quality of the type, conductivity type, resistivity, and the like of the wafer W and the epitaxial layer does not matter.

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

(Comparative Example 1)
The clearance between the susceptor concave portion and the chip was eliminated, and an epitaxial wafer was manufactured using a conventional arm portion (the bending rigidity of the inclined portion was 63 to 67 N · m ² ). The configuration of the epitaxial wafer manufacturing apparatus used at this time will be described below with reference to FIGS. That is, the susceptor 14 is configured by applying a SiC coat to a carbon base material. The susceptor 14 is configured for mounting a wafer having a diameter of 300 mm, that is, the wafer pocket 12 is set to have a diameter slightly larger than the diameter of 300 mm.

  The distance d1 (see FIG. 1) between the center line L1 of the susceptor 14 and the center of the susceptor recess 13 is 175.25 mm. The depth d2 of the susceptor recess 13 (see FIG. 2) is 1.8 mm. The shape of the susceptor recess 13 in plan view is a long hole (see FIG. 3). The long diameter d3 of the long hole is 5.8 mm, and the short diameter d4 is 5.3 mm.

  The chip 22 is made of SiC. The shape of the chip body 26 in plan view is a long hole (see FIG. 3). The long diameter d5 of the long hole is 5.5 mm, and the short diameter d6 is 5.15 mm. That is, the clearance (see FIG. 8) between the chip body 26 and the susceptor recess 13 is 0.3 mm (= 5.8 mm-5.5 mm).

  The axial length d8 (see FIG. 2) of the tip 22 is 24.1 mm. The axial length d9 (see FIG. 2) of the chip body 26 is 12.7 mm.

  The material of the arm body 21 is quartz. The length d10 in the axial direction of the vertical portion 24 (see FIG. 5) is 36.6 mm. The cross section when cut by a plane orthogonal to the axis of the vertical portion 24 is a rectangular shape of 6.6 mm × 8.1 mm. The diameter of the hole 25 (see FIG. 2) is 2.6 mm.

  The number of the arm portions 20 is three. The horizontal length d11 (see FIG. 5) of the inclined portion 23 is 169.15 mm. The vertical length d12 (see FIG. 5) of the inclined portion 23 is 67.6 mm. The length d13 (see FIG. 5) of the inclined portion 23 is 182.16 mm. The distance d14 (see FIG. 1) between the upper end 18a of the main support 18 and the lower surface 14b of the susceptor 14 is 95.1 mm.

The cross section of the inclined portion 23 when cut along a plane perpendicular to the center line L3 is rectangular. As shown in FIG. 5, the inclined portion 23 is configured to include a root portion 231 connected to the main support 18 and a portion 232 (hereinafter, referred to as a main portion) other than the root portion 231. The base portion 231 has a first portion 231a having a horizontal length d15 of 20 mm and a vertical length d16 of 20 mm, and a length d17 of the inclined portion 23 in the extending direction from the side near the main support 18. And a second portion 231b that is 15 mm. The bending rigidity of the main part 232 around the coordinate axis 100 (see FIG. 2) is 63 to 67 N · m ² .

  A silicon epitaxial layer was grown on the surface of a silicon wafer having a diameter of 300 mm, a crystal plane orientation (100), and a resistivity of 10 Ωcm. The thickness of the epitaxial layer was 4 μm, and the growth temperature was 1130 ° C.

  When the state of the arm portion 20 was confirmed after the epitaxial growth, breakage was confirmed at the contact portion A (see FIG. 2) between the chip 22 and the arm body 21.

  As described above, when the bending rigidity of the inclined portion 23 is large, the stress when the susceptor 14 is thermally deformed is not relieved by the bending of the inclined portion 23, but concentrates on the contact portion A, so that the contact portion A is broken. it is conceivable that.

(Example 1)
Thus, an epitaxial wafer was manufactured under the same epitaxial growth conditions as in Comparative Example 1, except that the bending rigidity of the main portion 232 (see FIG. 5) of the inclined portion 23 around the coordinate axis 100 (see FIG. 2) was set to 36 N · m ² or less. The configuration other than the bending rigidity of the main portion 232 is the same as that of the comparative example 1. When the state of the arm portion 20 was confirmed after the epitaxial growth, no damage was found.

From the above, it was found that even if the clearance between the chip 22 and the susceptor recess 13 was 0 mm, the breakage of the arm portion 20 could be suppressed by setting the bending rigidity of the inclined portion 23 to 36 N · m ² or less.

  The case where the clearance is maximum within the tolerance of the diameter of the chip body and the diameter of the susceptor recess used in Example 1 is 0.5 mm. Therefore, even if the clearance is not exactly 0 mm, if the clearance is 0.5 mm or less, it is considered that the clearance is within the tolerance range, and the same effect as when the clearance is 0 mm is considered to be obtained.

(Comparative Example 2)
An epitaxial wafer was manufactured under the same epitaxial growth conditions as in Example 1 and Comparative Example 1 by further reducing the bending stiffness of the main portion 232 of the inclined portion 23 and making the bending stiffness around the coordinate axis 100 less than 3 N · m ² . The configuration other than the bending rigidity of the main portion 232 is the same as that of the first embodiment and the first comparative example. When the state of the arm 20 was confirmed after the epitaxial growth, the arm 20 was sagged from the design position, and there was a problem in durability.

From Example 1 and Comparative Examples 1 and ² , it was found that the appropriate range of the bending rigidity of the inclined portion 23 was 3 to 36 N · m ² .

(Comparative Example 3)
The displacement of the susceptor and the displacement of the wafer (the displacement between the center of the wafer and the center of the wafer pocket) were measured when the conventional arm body 33 and the conventional chip 34 shown in FIG. 6 were used. The arm body 33 is the same as the arm body used in Comparative Example 1. As shown in FIG. 7, the shape of the susceptor recess 32 in plan view is a long hole having a diameter of 5.8 mm × 5.3 mm. The shape of the chip 34 in plan view is a circle having a diameter of 5.15 mm. Therefore, the clearance between the tip 34 and the susceptor recess 32 is 0.65 mm. The configuration of the epitaxial wafer growing apparatus other than the shape of the chip 34 and the clearance between the chip 34 and the susceptor recess 32 is the same as that of the comparative example 1.

  An epitaxial wafer was manufactured under the same epitaxial growth conditions as in Comparative Example 1. At this time, the wafer and the susceptor during the epitaxial growth were photographed with a camera, and the susceptor displacement amount and the wafer mounting displacement amount were obtained based on the photographed images. The amount of displacement of the susceptor was determined as the distance between the center of the susceptor (the position of the center line L1 of the susceptor 14 in the example of FIG. 1) and the center of rotation of the susceptor (the position of the center line L2 of the main support 18 in the example of FIG. 1). Further, the amount of displacement ΔE of the wafer is determined by the actual distance between the wafer edge portion and the wafer pocket with respect to the distance E1 between the wafer edge portion and the edge portion of the wafer pocket when the center of the wafer coincides with the center of the wafer pocket. The deviation amount of the interval E2 from the edge portion was obtained (that is, ΔE = E2−E1).

(Example 2)
The bending stiffness of the main part 232 (see FIG. 5) of the inclined part 23 around the coordinate axis 100 (see FIG. 2) is 6 N · m ² , and the other conditions are compared using an epitaxial wafer growth apparatus having the same configuration as that of the first embodiment. An epitaxial wafer was manufactured under the same epitaxial growth conditions as in Example 1. Then, in the same manner as in Comparative Example 3, the susceptor displacement amount and the wafer displacement amount were measured.

  Table 1 shows the results of Comparative Example 3 and Example 2. In Table 1, “n” indicates the number of experiments. “Max” indicates the maximum value among the results (susceptor displacement amount and mounting displacement amount) obtained in n experiments. “Avg” indicates the average value of the results obtained in n experiments. “Stdev” indicates the standard deviation of the results obtained in n experiments.

  As shown in Table 1, the susceptor displacement amount and the mounting displacement amount are smaller in Example 2 than in Comparative Example 3. In addition, the stdev (variation in the wafer mounting position) of the mounting displacement amount of the second embodiment is smaller than that of the comparative example 3.

  From the above, it was confirmed that by eliminating the clearance between the chip and the susceptor concave portion and reducing the bending rigidity of the inclined portion, the susceptor displacement amount, the wafer mounting displacement amount, and the wafer mounting position variation were suppressed. .

It should be noted that even in an epitaxial wafer growth apparatus different from the configuration (material and length of each part) of the epitaxial wafer growth apparatus used in the above embodiment, the clearance between the chip and the susceptor recess is in the range of 0 to 0.5 mm. When the bending rigidity of the inclined portion is in the range of 3 to 36 N · m ² , the stress caused by the thermal deformation of the susceptor can be reduced by the bending of the inclined portion, and thus, the variation in the wafer mounting position can be suppressed. Thus, damage to the arm can also be suppressed.

  Note that the present invention is not limited to the above embodiment. The above embodiment is an exemplification, has substantially the same configuration as the technical idea described in the claims of the present invention, and has the same function and effect, whatever It is included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Single-wafer type epitaxial wafer manufacturing apparatus 12 Wafer pocket 13 Susceptor recess 14 Susceptor 16 Support shaft 18 Main column 20 Arm part 21 Arm body 22 Chip 23 Inclined part 24 Vertical part

Claims (5)

A susceptor provided with a wafer pocket for mounting a wafer on the upper surface,
A support shaft for supporting and rotating the susceptor,
The support shaft has a rotatable main support provided in a vertical direction, and a plurality of arms provided on the main support and supporting a lower surface of the susceptor,
A plurality of susceptor recesses are formed on the lower surface of the susceptor,
The arm portion includes a chip constituting a head to be fitted into the susceptor recess, and an extending portion extending obliquely upward or horizontally from the main support , and the tip is connected to the tip. Arm body ,
The tip is a separate part from the arm body,
The head is closely fitted to the susceptor recess with a clearance of 0 to 0.5 mm,
A single-wafer epitaxial wafer manufacturing apparatus, wherein the extension portion has a bending rigidity of 36 N · m ² or less. The single wafer type epitaxial wafer manufacturing apparatus according to claim 1, wherein a bending rigidity of the extension portion is set to 3 N · m ² or more. 3. The single wafer epitaxial wafer manufacturing apparatus according to claim 1, wherein the arm body is made of quartz, and the chip is made of SiC .   The bending rigidity of the extending portion around a direction perpendicular to the cross section when the extending portion is cut by a plane which includes the center line of the extending portion in the plane and is parallel to the vertical direction is 36 N · m. ² The single wafer type epitaxial wafer manufacturing apparatus according to any one of claims 1 to 3, wherein the apparatus is set as follows. Method for producing an epitaxial wafer using the single-wafer epitaxial wafer manufacturing apparatus according to any one of claims 1-4.

Images