JP6687829B2 - Induction heating device - Google Patents

Description

  The present invention relates to an induction heating device that heats a wafer placed on a susceptor in a vacuum container.

  As a semiconductor manufacturing apparatus for forming a semiconductor single crystal on a material wafer, recently, a susceptor is placed in a vacuum container that can be hermetically sealed, and a high frequency current is applied to a coil to heat the susceptor. The induction heating device configured as above has been put into practical use. According to such an induction heating apparatus, the wafer placed on the susceptor is also heated, and it is possible to form a thin film on the surface of the wafer, the thickness and impurity concentration of which are precisely controlled.

  There is also known a device in which a heater is used as a heating source instead of the above-mentioned induction heating coil, and radiant heat from the heater is used to heat the susceptor. However, in an apparatus using such a heater as a heating source, it takes time to raise the temperature in the entire vacuum container to a necessary processing temperature, and it is difficult to shorten the process. Furthermore, the apparatus using a heater as a heat source is limited to a processing temperature of up to about 1200 ° C. Therefore, when a processing temperature of up to about 1800 ° C. is required, for example, excellent physical / chemical properties are required. It cannot be applied when manufacturing a silicon carbide (SiC) semiconductor, which is attracting attention as a device capable of realizing a small-sized and low-loss semiconductor device that surpasses a silicon (Si) semiconductor because of its existence.

  Against such a technical background, the above-described induction heating device that can handle a processing temperature up to about 1800 ° C. has been put into practical use.

  By the way, if the temperature distribution of the wafer is deviated during the heat treatment by the induction heating device, the required high-level processing treatment (thin film forming treatment) cannot be carried out and sufficient quality cannot be secured. . Therefore, the induction heating device is required to have a heat treatment for making the temperature distribution of the wafer uniform.

  Therefore, for example, in Patent Document 1 below, as a semiconductor manufacturing apparatus for heating a semiconductor, a plurality of susceptors each having a ring shape and having different diameters are separately arranged on a concentric circle, and an upper portion or a lower portion of the susceptor, Disclosed is a configuration in which induction heating coils are dividedly arranged as a high-frequency heating source for induction heating each susceptor. With such a configuration, by dividing the susceptor into a plurality of parts, the temperature control of the entire wafer heating can be precisely performed according to the number of divisions of the susceptor, and the temperature distribution of the wafer can be made uniform. It is thought possible to do.

JP, 2005-011868, A

  However, in the induction heating device described in Patent Document 1 described above, it is essential that a plurality of susceptors and a plurality of induction heating coils are arranged concentrically with respect to one wafer, and the concentric circles can be arranged in a predetermined manner. If it is not, there is a possibility that the desired highly accurate heat treatment cannot be carried out or the accuracy of the heat treatment is lowered.

  Further, although not mentioned in Patent Document 1, a configuration in which a plurality of susceptors and a plurality of induction heating coils must be arranged concentrically is adopted, and one vacuum container (inside the reaction chamber 20 in Reference Document 1) is adopted. ), A plurality of wafers are arranged in a multi-stage manner, and assuming an induction heating apparatus capable of performing heat treatment on each wafer, a plurality of susceptors and a plurality of susceptors arranged concentrically are arranged according to the number of wafer stages. Multiple combinations of induction heating coils are also required. Then, as the number of wafers that can be processed is set to be larger, the number of sets of the susceptor and the induction heating coil also increases, which leads to a complicated structure and complicated heating control of the induction heating coil unit that constitutes each set. There is a risk that the temperature distribution of each wafer cannot be made uniform. In particular, in order to make the temperature distribution of the wafer at a certain height position uniform, when the wafer is placed on the susceptor by induction heating with the induction heating coil forming the same set as the susceptor, the susceptor and It is necessary to consider the situation where the wafer mounted on the susceptor is also induction-heated by the induction heating coils that form another set, and it is expected that complicated control will be required for each set. .

  On the other hand, if the induction heating coil is placed outside the vacuum container instead of the configuration where an individual induction heating coil is placed for each susceptor, it is complicated to heat each induction heating coil for each susceptor. Control can be avoided. However, with such a configuration, among the plurality of susceptors arranged concentrically, the susceptor (outer susceptor, susceptor having a large diameter) arranged relatively close to the induction heating coil has priority. Therefore, it is difficult to uniformly heat the mounted wafer, and it is difficult to perform highly accurate heat treatment on the wafer. Such a problem also occurs in the induction heating apparatus in which the number of wafers that can be heat-treated in the heating chamber is set to one.

  In the first place, the technique of arranging a plurality of susceptors in a concentric pattern is based on induction heating if it is a well-known configuration in which a disk-shaped susceptor placed inside a heating chamber is heated by an induction heating coil placed outside the heating chamber. Based on the principle of the above, pay attention to the problem that the mounted wafer cannot be heated uniformly because only the edge portion near the induction heating coil in the disk-shaped susceptor is partially heated. It can be inferred that this was done. In particular, with the recent increase in the size of wafers, if the known disk-shaped susceptor is simply increased in size, the above problem becomes remarkable. However, a configuration in which a plurality of susceptors are arranged concentrically is disadvantageous in that the number of parts increases and the structure becomes complicated as described above.

  The present invention has been made paying attention to such a point, and a main object thereof is to uniformly heat a wafer mounted on a susceptor without inviting a complicated structure. An object is to provide an induction heating device.

That is, the induction heating device of the present invention includes a disk-shaped susceptor on which an SiC wafer can be placed on an upward surface, a vacuum container capable of keeping an internal space for accommodating the susceptor and the SiC wafer airtight, and an outside of the vacuum container. The present invention relates to an induction heating device including a wound coil and capable of heating a susceptor by induction heating by applying a high frequency current to the coil. Then, the induction heating device according to the present invention, as the susceptor, the thermal conductivity in the plane direction is higher than the thermal conductivity in the thickness direction, and while applying the graphite product having anisotropy in the thermal conductivity , The diameter of the susceptor is set to be larger than the diameter of the SiC wafer by a predetermined dimension, the center position of the SiC wafer is aligned with the center position of the susceptor, and the SiC wafer is placed on the susceptor. From the edge of the SiC wafer to the edge of the susceptor. the distance to, is characterized that you have set to 1.5 times to 2.0 times the penetration depth of the magnetic flux generated in the susceptor by the coil.

  With such an induction heating device, carbon (graphite material) having anisotropy in the plane direction, that is, the thermal conductivity in the plane direction is higher than that in the thickness direction, and the anisotropic thermal conductivity is obtained. Since the susceptor is made of carbon, which has a high anisotropy direction and the heat conduction direction is substantially aligned with the anisotropy direction, of the susceptor set to have a predetermined dimension larger than the diameter of the wafer, the outer peripheral portion (near the edge) Area) is heated by induction heating using high frequency, the entire susceptor, including the central part, can be heated uniformly based on the characteristics of the susceptor with high thermal conductivity and electrical conductivity in the plane direction. It is possible to make the temperature distribution within the mounted wafer uniform. Therefore, according to the induction heating apparatus according to the present invention, a problem resulting from the uneven temperature distribution in the wafer during the heat treatment, that is, it is difficult to perform a highly accurate heat treatment on the wafer, It is possible to prevent and suppress the occurrence of defects that adversely affect the manufactured semiconductor. Further, the induction heating device according to the present invention can shorten the process of raising the temperature to a predetermined process temperature, which is a merit of the induction heating system, as compared with a configuration adopting a heating system other than the induction heating. It is possible and contributes to shortening the whole process time.

  Particularly, in the induction heating device of the present invention, the diameter of the disk-shaped susceptor is set to be larger than the diameter of the wafer by a predetermined dimension, and the wafer is placed on the susceptor with the center position of the wafer aligned with the center position of the susceptor. Therefore, the mounting area of the wafer on the susceptor is an area avoiding the edge of the susceptor where the AC magnetic field penetrates and the vicinity thereof, and the magnetic flux passes through the wafer to cause the eddy current due to the AC magnetic field to cause the wafer on the susceptor to move. It is possible to uniformly heat the entire susceptor while avoiding a situation in which the wafer is affected, that is, a situation in which the wafer is damaged or the product becomes defective. Further, in the induction heating apparatus of the present invention, it is sufficient to prepare one disk-shaped susceptor for one wafer, so that, for example, a plurality of ring-shaped susceptors having different diameters are prepared and these ring-shaped susceptors are prepared. It is possible to simplify the structure and reduce the number of parts as compared with the configuration in which the parts are arranged concentrically.

  In the induction heating device according to the present invention, the diameter of the disk-shaped susceptor, when setting a predetermined dimension larger than the diameter of the wafer, a suitable condition, in the state of being placed with the center position of the wafer aligned with the susceptor. The condition that the distance from the edge of the wafer to the edge of the susceptor is set to be 1.5 to 2.0 times the penetration depth of the magnetic flux generated in the susceptor by the coil. If such a condition is satisfied, the wafer will be placed in a region where the eddy current due to the alternating magnetic field does not affect the wafer on the susceptor or is hardly affected, and in a region where the eddy current due to the alternating magnetic field is minimal. The magnetic flux passing through the coil can be made as close to zero as possible on the wafer, and it is possible to secure an environment during the heat treatment in which the eddy current does not affect or does not easily affect the wafer.

In addition, the induction heating device of the present invention may be a device that includes only one susceptor and heat-treats a single wafer placed on the susceptor. It is also possible to adopt a configuration in which a boat capable of supporting the susceptor in multiple stages is arranged in the vacuum container. Even with such an induction heating apparatus capable of batch processing, it is not necessary to arrange the coil in association with each susceptor, so the heat capacity is small compared to the configuration in which the coil is disposed in association with each susceptor, The structure can be simplified and the number of parts can be reduced.
Further, the induction heating device according to the present invention includes a disk-shaped susceptor on which an SiC wafer can be placed on the upward surface, a vacuum container capable of keeping an internal space for accommodating the susceptor and the SiC wafer in an airtight state, and a vacuum container. An induction heating device that is equipped with a coil wound outside and that can heat the susceptor by induction heating by generating a magnetic flux around the coil while applying a high-frequency current to the coil. The magnetic flux penetrates the susceptor. It has a peripheral region to be heated by the above and a central region to be heated by heat transfer from the peripheral region, and by mounting the SiC wafer on the central region of the susceptor, the influence of the eddy current due to the magnetic flux on the SiC wafer is reduced. It is characterized by doing.

  As described above, in the present invention, a disk-shaped carbon susceptor having anisotropy in the plane direction with respect to heat conduction and having the anisotropy direction substantially aligned with the direction of heat conduction is applied, and the diameter of the susceptor is changed. By setting the size larger than the diameter of the wafer and placing the wafer on the susceptor in a state where the center position of the wafer is aligned with the center position of the susceptor, without causing complication of the structure, It is possible to provide an induction heating device capable of shortening the temperature raising time and capable of uniformly heating a wafer placed on a susceptor.

The typical sectional view of the induction heating device concerning one embodiment of the present invention. The figure which shows typically the relative positional relationship of the susceptor and the wafer in the same embodiment.

  An embodiment of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1, the induction heating apparatus 1 according to the present embodiment includes a susceptor 2 on which a wafer W can be placed, a boat 3 that supports a plurality of susceptors 2 arranged in multiple stages, a susceptor 2 and a boat. The vacuum container 4 has excellent heat resistance and can accommodate 3 in the internal space 4S, and the coil 5 wound around the vacuum container 4.

  The vacuum container 4 is also called a tube because it has a cylindrical shape, and is a gas G (carrier gas, silicon source gas, carbon source gas) that is supplied from the air supply port 41 to the inside 4S of the vacuum container and flows upward. Etc.) can be discharged from the exhaust port 42. In the present embodiment, the air supply port 41 and the exhaust port 42 are formed near the lower end of the vacuum container 4. The vacuum container 4 divides the internal space 4S into a main space 4Sa that houses the susceptor 2 and the boat 3 and a sub-space 4Sb that extends in the height direction along the peripheral wall of the vacuum container 4, and these main spaces 4Sa The sub-space 4Sb is communicated with the sub-space 4Sb via the internal space 43S near the ceiling wall of the vacuum container 4, which has a partially spherical shape. In the present embodiment, the air supply port 41 is formed in a position that directly communicates with the main space 4Sa, and the exhaust port 42 is formed in a position that directly communicates with the sub space 4Sb. Therefore, the gas G supplied from the air supply port 41 to the main space 4Sa passes through the main space 4Sa in which the susceptor 2 and the wafer W are arranged, and then passes through the sub space 4Sb as shown in FIG. Exhausted from 42. That is, the main space 4Sa functions as a gas supply target space to which the gas G is supplied, and the sub space 4Sb functions as an exhaust path that is evacuated through the exhaust port 42. In addition, the supply amount of the gas G to the vacuum container 4S can be adjusted to the air supply port 41 to adjust the gas flow rate passing through the space (main space, heating chamber) in which the susceptor 2 and the wafer W are arranged. Gas supply control valve (not shown) is connected, a pressure adjusting valve (not shown) capable of adjusting the pressure in the vacuum container 4S is connected to the exhaust port 42, and a pressure adjusting device (not shown) connected to each of these valves is connected. Thus, each valve is controlled to adjust the pressure in the vacuum container 4S to a predetermined value. As the vacuum container 4, it is also possible to apply a water-cooled double structure.

  The coil 5 is an induction heating coil that is spirally arranged so as to surround the vacuum container 4 at a position apart from the outer wall of the vacuum container 4 by a predetermined distance. An unillustrated power supply device (high frequency power supply) capable of outputting AC power of an arbitrary frequency is connected to the induction heating coil 5 wound like a solenoid, and supplies AC power to the induction heating coil 5 from the power supply device. By doing so, an alternating magnetic field is generated around the induction heating coil 5, and this alternating magnetic field is permeated into the susceptor 2 which is an object to be permeated to perform induction heating.

  The susceptor 2 is a carbon susceptor made of graphite, which is a high melting point metal material having a melting point higher than the maximum temperature during the induction heating treatment. In this embodiment, the disk-shaped susceptor 2 having a predetermined thickness is arranged in a horizontal posture. Then, in the induction heating device 1 according to the present embodiment, the susceptor 2 is formed by the anisotropic graphite sheet having a large thermal conductivity in the surface direction. Specifically, for example, the susceptor 2 having a thermal conductivity of 200 W / m · K or more in the surface direction is applied. Further, in the present embodiment, the susceptor 2 having the conductivity in the plane direction of 1000 S / cm or more is applied. In this embodiment, the susceptor 2 having a thermal conductivity of 50 W / m · K or less in the thickness direction and a conductivity of 50 S / cm or less in the thickness direction is applied. The susceptor 2 of the present embodiment is formed by stacking a plurality of anisotropic graphite sheets having such a large thermal conductivity in the plane direction. This makes it possible to heat the surface of the susceptor 2 more uniformly. It should be noted that FIG. 1 and FIG. 2 described later show the entire susceptor 2 in which a plurality of graphite sheets are formed in a laminated shape, and the respective graphite sheets are omitted.

As shown in FIG. 2, the disc-shaped susceptor 2 applied in the present embodiment has a radius larger than the radius of the disc-shaped wafer W mounted on the susceptor 2 by a predetermined dimension. Specifically, the carbon susceptor 2 has a radius larger than that of the wafer W by a predetermined dimension L shown in FIG. In the present embodiment, the value of L is larger than the penetration depth (hereinafter referred to as “penetration depth δ”) generated in the susceptor 2 by the coil 5 (for example, from 1.5 times the penetration depth δ to 2). .0). Here, regarding the penetration depth, the relationship between the penetration current and the current flowing inside the conductor (heating body) at the portion x from the surface is:
Ix = Io exp (−x / δ)
However, it can be represented by Ix: current at the depth x from the surface, Io: eddy current flowing on the surface of the conductor, and δ: penetration depth. Therefore, the current flowing at the penetration depth δ becomes 1 / e = 0.37, and the current attenuated by 0.37 times the current flowing on the surface flows. This relationship is the same in a magnetic field.
The relationship between the frequency f and the penetration depth δ can be expressed by the following equation 1.

  As described above, the susceptor 2 of the present embodiment has a conductivity in the plane direction of 1000 S / cm or more and a resistivity of 1000 μ. Since it is Ω · cm, the penetration depth δ is 1.12 cm from the formula 1 when the frequency is 20 KHz. This means that when the frequency is 20 KHz, a large amount of magnetic flux enters a region of 1.12 cm from the outer edge 2E of the susceptor 2 toward the center 2S, and that portion is induction-heated. Therefore, the magnetic flux generated from the coil 5 generates an eddy current in a region (region 2A in FIG. 2) corresponding to the penetration depth δ, which is a predetermined region extending from the edge 2E of the susceptor 2 toward the center 2S, and generates a joule. The susceptor 2 is heated by the loss. From the above, it can be understood that in the susceptor 2, the heating power enters (passes) in the edge vicinity region 2A including the edge 2E.

  Then, the center WS is set by setting the radius of the susceptor 2 to be larger than the radius of the wafer W and larger than the penetration depth δ (current penetration depth δ) (1.5 to 2 times δ). It is possible to secure a situation in which the magnetic flux from the coil 5 to the susceptor 2 is extremely difficult to pass through the wafer W placed on the susceptor 2 in a posture matched with the center 2S of the susceptor 2. It is possible to prevent the defect that the wafer W is damaged. On the other hand, since the susceptor 2 configured by using the anisotropic graphite material having a large thermal conductivity in the surface direction is applied, the surface of the susceptor 2 is heated from the edge vicinity region 2A of the susceptor 2 heated by Joule loss. Heat is transmitted toward the central portion in the direction (in the direction of the arrow toward the center 2S of the susceptor 2 in FIG. 2), and the entire susceptor 2 can be soaked. Therefore, the entire temperature of the wafer W placed on the susceptor 2 can be equalized, and the temperature distribution in the wafer W can be made uniform.

  In the induction heating device 1 of the present embodiment, the center 2S of the susceptor 2 having such a configuration and characteristics is made to coincide with the center of the vacuum container 4, more specifically, the center of the main space 4Sa of the vacuum container 4. It is arranged in the main space 4Sa in a closed state.

  The boat 3 supports a plurality of susceptors 2 arranged in multiple stages at a predetermined pitch. With such a boat 3, the susceptor 2 on which the wafer W is placed can be stacked in multiple stages in the main space 4Sa of the vacuum container 4. Although FIG. 1 schematically illustrates the boat 3 capable of supporting 10 susceptors 2, it is also possible to apply a boat capable of supporting several tens or more susceptors 2. The boat 3 and the vacuum container 4 can be made of a material having excellent heat resistance that withstands a processing temperature of 1800 ° C., such as SiC. Further, when the processing temperature is 1200 ° C. or lower, a boat or a vacuum container made of quartz may be applied.

  In addition, in the induction heating device 1 of the present embodiment, a heat insulating material (not shown) that can exert a function of blocking the heat emitted from the susceptor 2 heated by the induction heating coil 5 from leaking to the outside of the vacuum container 4 ) Can also be arranged at an appropriate place. Examples of the heat insulating material include those made of a material having electrical conductivity and heat resistance and having a volume specific resistance sufficiently higher than that of the susceptor 2 which is a heating element. The heat insulating material and the susceptor 2 may be electrically insulated by an appropriate means.

  Although not shown, the induction heating device 1 of the present embodiment includes a thermometer that measures the internal temperature of the vacuum container 4 and an output control device that controls the output of the coil 5 based on the temperature measured by the thermometer. It is a thing.

  The induction heating apparatus 1 of the present embodiment having the above-described configuration causes the internal space 4S of the vacuum container 4 to function as a reaction chamber and heats the entire reaction chamber by a hot wall type CVD (Chemical Vapor Deposition / Chemical Vapor Deposition). , An epitaxial device, and a heat treatment device such as annealing.

  Next, operations and effects of the induction heating device 1 having such a configuration will be described.

  In the induction heating device 1 according to the present embodiment, the AC power is supplied from the power supply device to the coil 5 in a state where the susceptor 2 on which the wafer W is placed is supported by the boat 3 in a multi-stage manner. An alternating magnetic field is generated in the surroundings, and this alternating magnetic field permeates the susceptor 2 made of graphite and induction-heats the susceptor 2. At this time, the AC magnetic field penetrates much into the region (region 2A in FIG. 2) of the susceptor 2 from the outer edge (edge 2E) to a position closer to the center 2S by a distance corresponding to the penetration depth δ, While a large amount of electric power is supplied to this area 2A to heat the susceptor 2, the wafer W is not placed in the area 2A of the susceptor 2, that is, the area 2A in which a large amount of the AC magnetic field penetrates. The amount of penetration through the wafer W can be minimized (close to zero).

  Further, in this embodiment, the susceptor 2 having anisotropy in the plane direction, excellent thermal conductivity in the plane direction, and having electric resistance suitable for performing induction heating in the plane direction is applied. Therefore, when the region 2A near the edge 2E, which is a region where a large amount of the AC magnetic field penetrates, is heated in the susceptor 2, heat is transferred in the surface direction, and the entire susceptor 2 including the center 2S of the susceptor 2 is uniformly heated. It is possible to That is, a large amount of electric power is applied to the edge 2E of the susceptor 2 due to induction heating by the coil 5, and the electric power is reduced to 0.14 times the electric power of the surface (edge 2E of the susceptor 2) at the penetration depth δ (heating power). Is expressed by I ^ 2 × R, so the current is squared at the penetration depth δ portion), and the electric power weakens as it approaches the inside (center side) of the penetration depth δ, but it is anisotropic in the plane direction. Since the susceptor 2 having the property of being applied is applied, when the region 2A near the edge 2E, which is a region in which a large amount of AC magnetic field penetrates, is heated in the susceptor 2, heat is transferred in the surface direction and the center 2S of the susceptor 2 is transmitted. The entire susceptor 2 including can be brought into a uniform heating state.

  By the above processing, each susceptor 2 is uniformly heated in the surface direction, and the wafer W placed on each susceptor 2 can be uniformly heated to a predetermined target temperature (epitaxial growth temperature, for example, 1800 ° C.). When the predetermined process is reached, the output of the coil 5 (the output of the coil 5 according to the amount of AC power supplied from the power supply device to the coil 5) is controlled so as to maintain the temperature, and the high temperature equilibrium state is reached. To maintain. Further, the pressure adjusting device controls the gas supply control valve and the pressure adjusting valve so that the pressure value in the vacuum container 4S becomes a predetermined value. If the heat insulating material is arranged in the vacuum container 4S and closer to the peripheral wall side of the vacuum container 4 than the susceptor 2, the alternating magnetic field generated around the coil 5 passes through the heat insulating material. Will penetrate into the susceptor 2.

  The induction heating apparatus 1 according to the present embodiment maintains a high temperature (approximately 1800 ° C.) equilibrium state through the above-described processing, and a thin film having a uniform film thickness on the surface of the wafer W placed on each susceptor 2. In the present embodiment, it is possible to form a single crystal SiC thin film (also referred to as a SiC epi film and hereinafter referred to as “SiC thin film”). Then, since the growth rate of the SiC thin film increases in proportion to the supply amount of the source gas G supplied from the air supply port 41 to the vacuum container 4S (gas supply target space, main space 4Sa), the gas G is efficiently supplied. By heating to sufficiently decompose and supply the gas G, it is possible to obtain high-speed growth of the SiC thin film. That is, the induction heating device 1 according to the present embodiment functions as a CVD epitaxial device that realizes epitaxial growth for forming a SiC thin film on the wafer W, and produces an epitaxial wafer W on which a SiC thin film is deposited by epitaxial growth. can do.

  The induction heating apparatus 1 of the present embodiment can stably supply a high-quality epitaxial wafer in which a SiC thin film whose thickness and impurity concentration are precisely controlled is deposited on the wafer W, and is suitable for practical use of SiC semiconductor devices. Contribute to many.

  As described above, the induction heating device 1 according to the present embodiment has the technical idea that has not been conceived up to now, that is, the susceptor 2 formed of carbon (graphite material) having anisotropy in the plane direction. By adopting the technical idea of applying, when the outer peripheral portion (the area 2A near the edge) of the susceptor 2 is heated by the induction heating process using the high frequency, the susceptor 2 having a high thermal conductivity and a high electrical conductivity in the surface direction is obtained. Based on the characteristics, the entire susceptor 2 including the central portion can be uniformly heated, and the temperature distribution in the wafer W placed on the susceptor 2 can be made uniform. Therefore, according to the induction heating device 1 according to the present embodiment, a defect caused by uneven temperature distribution, that is, a defect that adversely affects the resistivity of a manufactured semiconductor, the lifetime of carriers (long life), and the like. Can be prevented or suppressed. In addition, the induction heating device 1 according to the present embodiment aims to shorten the processing time for raising the temperature to a predetermined processing temperature, which is an advantage of the induction heating method, as compared with a configuration that employs a heating method other than the induction heating method. It is also possible to contribute to shortening the whole process time.

  In particular, the induction heating apparatus 1 according to the present embodiment sets the diameter of the susceptor 2 to be larger than the diameter of the wafer W by a predetermined dimension (specifically, the diameter of the susceptor 2 is larger than the diameter of the wafer W by a penetration depth δ of 1). The size is set to 0.5 to 2.0 times), and the wafer W is not mounted on the edge vicinity region 2A of the susceptor 2 where the AC magnetic field penetrates a lot, but by the eddy current generated by the AC magnetic field. Since the wafer W on the susceptor 2 is placed in an area where the wafer W is not affected or hard to be affected, and an area where the eddy current due to the alternating magnetic field is minimal, a large amount of magnetic flux is applied to the wafer W. It is possible to avoid the situation of passing through and to uniformly heat the entire susceptor 2 under a situation where the wafer W is not affected by the eddy current or is less likely to occur. As a result, it is possible to avoid the destruction of the wafer W and the production of defective products.

  In addition, in the induction heating apparatus 1 of the present embodiment, the boat 3 that supports the plurality of susceptors 2 in multiple stages is arranged in the vacuum container 4S. Therefore, the batch processing that simultaneously performs the processing on the plurality of wafers W is performed. It is possible to improve the processing efficiency. In addition, since the induction heating apparatus 1 is capable of batch processing, the coil is not individually arranged in association with each susceptor. Therefore, the coil is individually arranged in association with each susceptor. In comparison, the heat capacity is small, and the structure can be simplified and the number of parts can be reduced.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the induction heating apparatus that functions as an apparatus for forming an epitaxial growth film on a wafer by chemical vapor deposition (CVD) is illustrated, but the induction heating apparatus of the present invention is a chemical vapor deposition apparatus. It can also function as an apparatus for forming a useful film other than the epitaxially grown film on the wafer by (CVD).

  Further, the induction heating device may be a device that performs an appropriate treatment using a chemical reaction on a wafer that is an object to be heated, or appropriately uses sintering or melting on the object to be heated. The processing may be performed.

  Further, the susceptor may be any one having anisotropy in the plane direction, and the values of thermal conductivity in the plane direction and electric conductivity in the plane direction are not particularly limited. Furthermore, in the present invention, the distance from the edge of the wafer to the edge of the susceptor in a state where the wafer is placed on the susceptor with the center position aligned with the susceptor is within a range that does not affect the wafer. It can be set to a value greater than 2.0 times the penetration depth of the generated magnetic flux, or a value smaller than 1.5 times the penetration depth of the magnetic flux generated in the susceptor by the coil. is there.

  In the above-described embodiment, a plurality of susceptors are arranged in a multi-stage manner in the vacuum container, and an induction heating device capable of performing heat treatment on a plurality of wafers at the same time is illustrated. However, one susceptor is arranged in the vacuum container. It may be an induction heating device capable of performing heat treatment on one wafer placed on the susceptor.

  The high frequency used during the heat treatment is preferably 1 KHz or higher, but is not particularly limited. Since the penetration depth δ of the electric current also changes depending on the value of the high frequency, the diameter of the susceptor is appropriately set so that the wafer can be placed on the upper surface of the susceptor in the heated state except the region where the AC magnetic field from the coil penetrates. Set to the value of.

  The susceptor may not be formed by stacking sheet-shaped graphite materials, but may be formed by using a single block-shaped or sheet-shaped graphite material.

  Furthermore, the susceptor may be a graphite material having anisotropy in the plane direction, which is coated with SiC. In this case, it is possible to avoid the situation where the graphite material and the wafer come into direct contact with each other, it is possible to suppress contamination of the wafer and generation of useless particles, and it is expected to reduce an unintended reaction with the process gas.

  In addition, the specific configuration of each unit is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 ... Induction heating device 2 ... Susceptor 3 ... Boat 4 ... Vacuum container 5 ... Coil W ... Wafer

Claims (3)

A disk-shaped susceptor on which an SiC wafer can be placed on the upward surface,
A vacuum container capable of holding an internal space containing the susceptor and the SiC wafer in an airtight state;
A coil wound on the outside of the vacuum container,
An induction heating device capable of heating the susceptor by induction heating by applying a high frequency current to the coil,
The susceptor has a higher thermal conductivity in the plane direction than the thermal conductivity in the thickness direction , and is made of graphite having anisotropy in thermal conductivity ,
The diameter of the susceptor is set to be larger than the diameter of the SiC wafer by a predetermined dimension, the center position of the SiC wafer is aligned with the center position of the susceptor, and the SiC wafer is placed on the susceptor . the distance from edge to edge of the susceptor, the induction heating device characterized that you have set to 1.5 times to 2.0 times the penetration depth of the magnetic flux generated in the susceptor by the coil. A disk-shaped susceptor on which an SiC wafer can be placed on the upward surface,
A vacuum container capable of holding an internal space containing the susceptor and the SiC wafer in an airtight state;
A coil wound on the outside of the vacuum container,
An induction heating device capable of heating the susceptor by induction heating by generating a magnetic flux around the coil while applying a high-frequency current to the coil,
The susceptor has a peripheral region heated by the penetration of the magnetic flux, and a central region heated by heat transfer from the peripheral region,
An induction heating apparatus , wherein the influence of an eddy current due to the magnetic flux on the SiC wafer is reduced by placing the SiC wafer on the central region of the susceptor . The SiC wafer is placed with its center position aligned with the center position of the susceptor,
The frequency of the high-frequency current before applying to the coil is 1 kHz or more,
The distance from the edge of the SiC wafer to the edge of the susceptor is set to 1.5 times to 2.0 times the penetration depth of the magnetic flux generated in the susceptor by the coil,
The induction heating device according to claim 2, wherein a boat capable of supporting a plurality of the susceptors in multiple stages is arranged in the vacuum container.

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