JP6101591B2 - Epitaxial wafer manufacturing apparatus and manufacturing method - Google Patents

Description

  The present invention relates to an epitaxial wafer manufacturing apparatus and manufacturing method in which an epitaxial layer is deposited and grown on the surface of a heated wafer while supplying a source gas into the chamber.

  Silicon carbide (SiC) has excellent physical properties of about 3 times the band gap, about 10 times the dielectric breakdown electric field strength, and about 3 times the thermal conductivity of silicon (Si). Application to high-frequency devices, high-temperature devices, etc. is expected.

  A SiC epitaxial wafer is usually used for manufacturing a semiconductor device using SiC. This SiC epitaxial wafer is obtained by epitaxially growing a SiC single crystal thin film (SiC epitaxial layer), which becomes an active region of a SiC semiconductor device, on the surface of a SiC single crystal substrate (SiC wafer) manufactured using a sublimation recrystallization method or the like ( Crystal growth).

  As an epitaxial wafer manufacturing apparatus, a chemical vapor deposition (CVD) apparatus is used in which a SiC epitaxial layer is deposited and grown on the surface of a heated SiC wafer while supplying a source gas into the chamber. The epitaxial growth of SiC is performed at a high temperature of 1500 ° C. or higher. As a CVD method used for epitaxial growth of SiC, there are various forms such as a method of flowing a gas in the horizontal direction and a method of flowing a gas in the vertical direction. The horizontal hot wall method described in Patent Document 1 and Patent Document 2 and the self-revolving CVD apparatus described in Patent Documents 3 to 5 are typical. In either method, epitaxial growth is performed by circulating a source gas on a SiC substrate held at a high temperature.

  When the source gas is circulated, the film thickness and doping concentration of the epitaxial growth tend to be non-uniform between the upstream side and the downstream side. For this reason, in recent manufacturing apparatuses, a gas (rotating gas) is caused to flow into the bottom surface of a wafer support (satellite) housed in a housing portion of a mounting plate (susceptor) and rotated to thereby generate SiC during crystal growth. The wafer is rotated to eliminate non-uniformity such as film thickness on the SiC wafer (see Patent Document 2). In addition, as a manufacturing apparatus for epitaxial growth on a plurality of SiC wafers at the same time, a mounting plate that accommodates a plurality of wafer support tables rotates (revolves), and the wafer support table itself rotates (revolves). Are used (see Patent Documents 3 to 5).

  There was also a type of device in which the rotating gas enters the chamber. In this type of device, when Ar (argon) gas is used as the rotating gas, this Ar gas is mixed into the hydrogen gas of the carrier gas and Si (silicon) ) This causes the formation of droplets, and there is a problem that the Si droplets cause defects (shallow pits) in the epitaxial film. For this reason, there is a type of device in which the rotating gas flows out of the chamber.

  By the way, in the conventional epitaxial wafer manufacturing apparatus, when the process of forming the SiC epitaxial layer is performed, the raw material is deposited not only on the surface of the SiC wafer but also on the surface of the ceiling (top plate). By repeating this process, the deposition of the raw material of the SiC epitaxial layer increases on the surface of the sealing, but a part of the deposit may peel off and fall on the surface of the SiC wafer. In this case, the fallen deposit is embedded inside the SiC epitaxial layer being processed or adhered to the surface, thereby adversely affecting the film quality of the SiC epitaxial layer as particles (downfall). .

  Therefore, it is necessary to prevent particles from adhering to the surface to be processed of the SiC wafer before crystal growth. Therefore, in the conventional manufacturing apparatus, the gas leaking from the gap between the housing portion and the wafer support table (ie, SiC) is increased by increasing the flow rate of the rotating gas for rotating the wafer support table until just before the crystal growth. The amount of gas that passes through the side surface of the wafer is increased, and the gas flow may prevent (purging or blocking) the approach of particles to the surface to be processed of the SiC wafer. In the manufacturing apparatus in this case, a gas that flows before crystal growth in order to prevent particles from approaching and a gas that flows during crystal growth to suppress nonuniformity of characteristics on the wafer flow through the same flow path.

  However, if the flow rate of the rotating gas is increased in order to enhance the purging or blocking effect, the rotational speed of the wafer support table (the number of rotations per unit time) becomes too fast, and the SiC wafer is displaced from the wafer support table. May occur. In this case, the generation of particles due to the friction between the wafer support and the mounting plate becomes a problem. In addition, the rotating gas takes part of the heat of the wafer support, but if the flow rate of the rotating gas is increased from the flow rate during crystal growth while heating the wafer, the temperature of the wafer greatly decreases, and then the growth starts. When the flow rate of the rotating gas is returned to the flow rate at the time of crystal growth in accordance with the above, the wafer temperature greatly changes immediately before the crystal growth.

JP 2008-270682 A JP 2011-18772 A JP-A-1-278498 US Pat. No. 5,788,777 JP-T-2004-507619

  The present invention has been proposed in view of such conventional circumstances, and it is possible to stably deposit and grow a high-quality epitaxial layer on the surface of a wafer while reducing the above-described particles. An object of the present invention is to provide an epitaxial wafer manufacturing apparatus and method.

The present invention provides the following means.
(1) An epitaxial wafer manufacturing apparatus for depositing and growing an epitaxial layer on the surface of a heated wafer while supplying a source gas into the chamber,
In the chamber,
A mounting plate provided with a recess on one side;
Between the inner wall surface of the concave portion, with a gap so as to be rotatable, and at least a wafer support base accommodated in the concave portion,
The mounting plate is
A first flow path having one end on the inner wall surface of the recess, connected to the reaction space in the chamber through the gap, and flowing a first gas that prevents particles from approaching the surface to be processed of the wafer When,
And a second flow path having one end on the inner wall surface of the recess, connected to the gap, and flowing a second gas for rotating the wafer together with the wafer support. Epitaxial wafer manufacturing equipment.
(2) The epitaxial wafer manufacturing apparatus according to (1), wherein one end of the first flow path is connected to an inner bottom surface of the inner wall surface of the recess.
(3) One end of the first flow path is provided at a position on the upstream side and / or the downstream side when flowing the source gas into the chamber at least on the inner bottom surface of the inner wall surface of the recess. The epitaxial wafer manufacturing apparatus as described in (1) or (2) above, wherein
(4) On the inner wall surface of the recess, a rotating gas discharge hole that penetrates the inside of the mounting plate from a position between one end of the first flow path and one end of the second flow path. The apparatus for manufacturing an epitaxial wafer according to any one of the above items (1) to (3), wherein:
(5) A method for manufacturing an epitaxial wafer, in which an epitaxial layer is deposited and grown on the surface of a heated wafer while supplying a source gas into the chamber,
A growth step of depositing and growing the epitaxial layer on the surface of the wafer while rotating the wafer support and the wafer placed thereon using a second gas;
Before the growth step, the first gas that flows upward through the side surface of the wafer is flowed using a flow path that is provided separately from the flow path through which the second gas flows. Production method.
(6) The method for producing an epitaxial wafer as described in (5) above, wherein a gas containing argon is used as the first gas.
(7) The method for producing an epitaxial wafer as described in (5) or (6) above, wherein a gas comprising a hydrogen element is used as the second gas.
(8) The method for producing an epitaxial wafer as described in (5) above, wherein a gas comprising a hydrogen element is used as the first gas, and a gas containing an argon element is used as the second gas.

The epitaxial wafer manufacturing apparatus according to the present invention purges particles approaching the surface to be processed of the wafer separately from the second gas flow path for rotating the SiC wafer to make the SiC wafer crystal film uniform ( Or a first gas flow path. Therefore, the first gas is supplied from a different flow path from the second gas. For this reason, it is possible to flow the first gas for purging particles approaching the surface to be processed of the wafer independently of the second gas for rotating the SiC wafer. Then, without rotating the wafer support table, it is possible to prevent the particles from approaching the processing surface of the wafer by flowing the first gas. With this rotation, the wafer support table and the mounting plate rub against each other. In addition to preventing the generation of particles, it is possible to prevent the occurrence of positional deviation of the SiC wafer with respect to the wafer support.
Alternatively, even if the wafer support is configured to rotate by flowing a rotating gas, it is not necessary to increase the flow rate of the rotating gas from the flow rate during crystal growth in order to increase the purge effect or the blocking effect. The purge effect or blocking effect can be enhanced by flowing the first gas without increasing the generation of particles due to friction between the wafer support and the mounting plate, and without increasing the occurrence of displacement of the SiC wafer.
In addition, in order to increase the purge effect or blocking effect at the time of temperature rise, it is not necessary to increase the flow rate of the rotating gas from the flow rate during crystal growth, so it is necessary to return the flow rate of the rotating gas to the flow rate during crystal growth immediately before crystal growth. There is no significant change in the temperature of the SiC wafer before and after crystal growth.

In the epitaxial wafer manufacturing method according to the present invention, the first gas for purging (or blocking) particles approaching the surface to be processed of the wafer is rotated, and the SiC wafer is rotated in order to uniformize the crystal film formation of the SiC wafer. It introduce | transduces using a means independent from the 2nd gas to make. Therefore, since the first gas is supplied from a different flow path from the second gas, the first gas is introduced into the reaction space without rotating the wafer support, and particles are generated on the surface to be processed of the wafer. It can prevent approaching. For this reason, there is no possibility of generation of particles due to friction between the wafer support base and the mounting plate, and displacement of the SiC wafer relative to the wafer support base due to rotation.
Alternatively, even if the wafer support is rotated by flowing a rotating gas, it is not necessary to increase the flow rate of the rotating gas from the flow rate during crystal growth in order to increase the purge effect or blocking effect. The purge effect or the blocking effect can be enhanced by flowing the first gas without increasing the generation of particles due to friction with the mounting plate and without increasing the occurrence of displacement of the SiC wafer.
In addition, since it is not necessary to increase the flow rate of the rotating gas more than the flow rate at the time of crystal growth in order to enhance the purge effect or the blocking effect at the time of temperature rise, the temperature of the SiC wafer does not change greatly.

It is a cross-sectional schematic diagram which shows 1st Embodiment of the manufacturing apparatus of the epitaxial wafer to which this invention is applied. It is a cross-sectional schematic diagram which expands and shows the principal part which comprises 1st Embodiment of the manufacturing apparatus of the epitaxial wafer to which this invention is applied. It is a plane schematic diagram which shows an example of the mounting plate to which this invention is applied.

  Hereinafter, an epitaxial wafer manufacturing apparatus to which the present invention is applied will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the characteristics easy to understand, there are cases where the characteristic portions are enlarged for the sake of convenience, and the dimensional ratios and the like of the respective components are not always the same as the actual ones. Absent. In addition, the materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not necessarily limited thereto, and can be appropriately modified and implemented without departing from the scope of the invention. .

(1) First Embodiment (Epitaxial Wafer Manufacturing Apparatus)
FIG. 1 is a schematic cross-sectional view showing a first embodiment of an epitaxial wafer manufacturing apparatus to which the present invention is applied. An epitaxial wafer manufacturing apparatus 1 to which the present invention is applied is, for example, a CVD apparatus as shown in FIG. 1, and heats a SiC wafer W in a chamber (film formation chamber) 2 that can be evacuated under reduced pressure. While supplying the gas G, a SiC epitaxial layer (not shown) is deposited and grown on the surface of the heated SiC wafer W. As the source gas G, for example, a gas containing silane (SiH ₄ ) as a silicon (Si) source and propane (C ₃ H ₈ ) as a carbon (C) source can be used, and hydrogen as a carrier gas. Those containing (H ₂ ) can be used. The gas G supplied from the center of the epitaxial wafer manufacturing apparatus 1 flows over the SiC wafer and is exhausted from the outer peripheral portion of the reaction space K to the outside of the chamber 2 (exhaust port not shown).

  The manufacturing apparatus 1 is attached to the chamber 2, a wafer support 3 (satellite) 3 that supports the SiC wafer W inside the chamber 2, a mounting plate (susceptor) 4 that mounts the wafer support 3, and the chamber 2. Means for raising the temperature inside the chamber 2, and means for supplying the source gas G to the inside of the chamber 2 attached to the chamber 2. The reaction space K in the manufacturing apparatus 1 is surrounded by a ceiling (top plate) 2 </ b> A, a peripheral wall 2 </ b> B, and a mounting plate 4 that constitute the chamber 2.

  The mounting plate 4 forms a disk-shaped rotary table, and a rotary shaft 7 is attached to the center of the lower surface 4b. On the upper surface 4a side of the mounting plate, a plurality of concave accommodating portions (concave portions) 8 for accommodating the disk-shaped wafer support base 3 that supports the SiC wafer W are provided. The recesses 8 have a circular shape in a plan view as viewed from the upper surface 4a side, and a plurality of the recesses 8 are provided at equal intervals in the circumferential direction of the upper surface 4a (the rotation direction of the mounting plate 4). The mounting plate 4 is integrated with the rotary shaft 7 and is rotatably supported so that the direction of the normal line of the upper surface 4a is constant.

FIG. 2 is an enlarged cross-sectional view of the main part A including the features of the present invention in the manufacturing apparatus 1 shown in FIG. As shown in FIG. 2, the wafer support 3 has an outer diameter slightly smaller than the inner diameter of the recess 8, and is supported by the pin-shaped small protrusion 12 at the center of the bottom surface of the recess 8. In the recess 8, it is rotatable about the small protrusion 12 as a central axis. The inner wall surface of the recess 8 has a gap L between the side surface of the wafer support 3 so that the accommodated wafer support 3 can rotate.
The clearance L includes a clearance L1 between the inner bottom surface 8a of the recess 8 and the outer bottom surface 3b of the wafer support 3 and a clearance L2 between the inner surface 8c of the recess 8 and the outer surface 3c of the wafer support 3. Including. In the configuration shown in FIG. 1, the gap L1 is formed by the wafer support 3 being supported by the small protrusions 12, but the configuration of the gap L1 is not limited to this. Without providing the small protrusions 12, for example, a plurality of convex portions that support the wafer support 3 may be provided on the inner bottom surface 8a of the concave portion 8, and the gap L1 may be provided by a gap between the convex portions.

  As shown in FIG. 2, the wafer support base 3 has an outer edge portion of the upper surface 3a that is recessed in the thickness direction, and a wafer holder 9 is disposed here. Wafer holder 9 has an annular shape, and is arranged at the outer edge portion of upper surface 3a of the wafer support base so as to fill the recessed portion and to protrude on the upper surface 3a side by the thickness of SiC wafer W to be mounted or more. The inner diameter of the ring constituting the wafer holder 9 is at least larger than the outer diameter of the SiC wafer to be placed. In the thickness direction d of the mounting plate, when the positions of the protrusions of the wafer holder 9 and the processing surface Wa of the SiC wafer to be placed are not aligned, the flow of the raw material gas G is disturbed (the laminar flow) Disturbance is likely to occur, and the epitaxial layer may not be formed uniformly in the plane of the SiC wafer W. Therefore, it is preferable that the protrusion part of the wafer holder 9 and the to-be-processed surface Wa of the SiC wafer to be placed are substantially on the same plane.

  When there is a gap between the side surface of the SiC wafer W and the wafer holder 9, there is a possibility that the SiC crystal is deposited there, and the SiC wafer W is lifted from the upper surface (mounting surface) 4 a of the mounting plate. Accordingly, the gap between the SiC wafer W and the wafer holder 9 is preferably filled as much as possible. For example, when the SiC wafer W has an orientation flat (OF), the wafer holder Of the inner peripheral shape of 9, the portion corresponding to the orientation tension flat may be linear.

  By forming the wafer holder 9 with the same material as the SiC wafer W, it is possible to reduce variations in the characteristics around the SiC wafer W. Therefore, it is desirable to use a wafer holder 9 made of silicon carbide, which is the same material as SiC wafer W. Since the deposited SiC adheres firmly to the surface of the wafer holder 9, it rarely peels off and becomes particles.

The mounting plate 4 includes a first flow path 10 for flowing the first gas G1 and a second flow path 11 for flowing the second gas G2. The first gas G1 is a gas used to prevent the particles P from approaching the surface Wa of the SiC wafer.
The heavier element gas such as argon (Ar) has a larger effect (purge effect or block effect) of purging or blocking particles approaching the surface Wa of the SiC wafer. However, Ar gas forms Si droplets by mixing with hydrogen gas as a carrier gas, and these Si droplets become shallow pits in the epitaxial layer. Therefore, in a situation where there is no risk of Si droplet formation before crystal growth (epitaxial layer formation), it is preferable to use Ar gas (or a gas containing Ar gas), which is a heavy element, as the purge gas, but there is a risk of Si droplet formation. In certain situations, it is preferable to use hydrogen gas as the carrier gas as the purge gas.

As shown in FIG. 1, the first flow path 10 has one end 10 a that opens at the inner wall surface of the recess 8, and the one end 10 a is formed between the inner wall surface of the recess 8 and the wafer support 3. The other end 10 b is connected to the first gas supply means 13. Furthermore, one end 10 a of the first flow path is indirectly connected to the reaction space K through the gap L. The gap L in this case forms a flow path that relays between the first flow path 10 and the reaction space K. Note that one end 10 a of the first flow path is preferably connected to the gap L on the inner bottom surface of the inner wall surface of the recess 8.
Since the source gas G is deposited more on the upstream side and the downstream side when flowing into the chamber 2, at least one end portion 10a of the first flow path is a reaction space at the upstream side and / or downstream side position. It is preferable to communicate with K. That is, one end 10 a of the first flow path is preferably provided on the inner wall surface of the recess 8 at a position on the upstream side and / or the downstream side when the source gas G flows in the chamber 2. Although FIG. 1 shows an example in which the first gas supply means 13 is arranged at a position facing the lower surface 4b of the mounting plate, the position of the first gas supply means 13 is not limited to this position.

The second gas G2 is a gas (rotating gas) used to rotate the SiC wafer W together with the wafer support 3 so that the film formation is uniform in the plane when the film is formed on the SiC wafer W by epitaxial growth. It is. As the second gas G2 (rotating gas), for example, Ar gas or a mixed gas of Ar and hydrogen is used. In the type of apparatus in which the second gas G2 (rotating gas) enters the chamber, the second gas G2 is used. It is preferable to use a gas composed of hydrogen molecules (H ₂ ) used as a carrier gas together with the source gas G. This is because when Ar gas is mixed into the hydrogen gas of the carrier gas, Si droplets that cause defects (shallow pits) in the epitaxial layer are formed.

  As shown in FIG. 1, the second flow path 11 has one end 11 a that opens on the inner wall surface of the recess 8, and the one end 11 a is formed between the inner wall surface of the recess 8 and the wafer support 3. The other end 11 b is connected to the second gas supply means 14. The mounting plate 4 is provided with a rotating gas exhaust hole 15 for exhausting the rotating gas G2 from the space below the wafer support 3 in order to exhaust the rotating gas G2 directly outside the chamber 2 as shown in FIG. It may be left. If the rotary gas exhaust hole 15 is provided, the second gas G2 flowing in from the second flow path 11 flows in a predetermined flow path (groove of FIG. 3 to be described later) in a space between the recess 8 and the wafer support 3. 8b), it is discharged to the outside from the lower surface side 4b of the mounting plate through the rotary gas exhaust hole 15. Therefore, since the rotating gas G2 does not directly enter the reaction space K, the type and flow rate of the rotating gas G2 can be arbitrarily selected without considering the influence on the reaction space K. The rotary gas discharge hole 15 penetrates the inside of the mounting plate 4 from the position between the one end 10a of the first flow path and the one end 11a of the second flow path on the inner wall surface of the recess 8. It is preferable to be provided. Although FIG. 1 shows an example in which the second gas supply means 14 is arranged at a position facing the lower surface 4b of the mounting plate, the position of the second gas supply means 14 is not limited to this position.

FIG. 3 is a plan view of the mounting plate 4 as viewed from the upper surface 4a side. The mounting plate 4 includes six recesses 8 on the upper surface 4a. In FIG. 3, the opening of the rotary gas discharge hole 15 shown in FIGS. 1 and 2 is omitted. The bottom surface 8a of each recess is provided with three grooves 8b extending outwardly while drawing an arc from the center portion, and the second gas inflow hole (one of the second flow paths) is located near the center portion of each groove 8b. An end 11a) is provided. The groove 8b has a shape that guides the second gas G2 to rotate on the bottom surface 8a of the recess. With such a structure, as the second gas G2 flowing in from the one end 11a of the second flow path flows through the groove 8b, the wafer support table 3 in contact with the second gas G2 is in contact. Rotation is prompted.
In addition, in order to keep the direction of the rotation axis of the wafer support 3 and the wafer W constant so that the film formation is uniform in the plane of the wafer W, the grooves 8b are preferably provided at two or more locations. It is more preferable if it is provided at three or more locations.

  In addition, three inflow holes (one end portion 10a of the first flow path) of the first gas G1 are provided in the outer edge portion of the bottom surface 8a of each recess, and the first gas G1 flowing in from the first gas G1 It passes through the space sandwiched between the inner wall surface of the recess 8 and the wafer support 3 and flows out into the reaction space K. Since this space extends linearly in the thickness direction d of the mounting plate 4, the first gas G <b> 1 can pass with the momentum substantially maintained, and in the reaction space K, with respect to the upper surface 4 a of the mounting plate. In the vertical direction. Thereby, particles approaching the surface Wa of the SiC wafer can be strongly blocked. Furthermore, it is preferable that one end 10 a of the first flow path is provided on the inner bottom surface of the inner wall surface of the recess 8. In this case, since the first gas G does not affect the rotation of the wafer support 3, the flow rate of the first gas G can be set regardless of the rotation of the wafer support 3.

  The mounting plate 4 employs a so-called planetary (self-revolving) system. The mounting plate 4 is rotationally driven around a central axis thereof while the rotational shaft 7 is rotationally driven by a drive motor (not shown). The plurality of wafer support tables 3 are rotationally driven around their respective central axes when a driving gas different from the source gas G is supplied between the lower surface 3b of each wafer support table and the accommodating portion. It is structured (not shown). Thereby, it is possible to form a film evenly on each SiC wafer W placed on the plurality of wafer support tables 7.

  The sealing 2A is a disk-shaped member having a diameter substantially coincident with the mounting plate 4, and forms a flat reaction space K between the mounting plate 2 and the upper surface 4a. The peripheral wall 2B is a ring-shaped member that surrounds the outer periphery of the mounting plate 4 and the sealing 2A.

  As a means for raising the temperature inside the chamber 2, for example, as shown in FIG. 1, an induction coil 5 that can heat the mounting plate 4 and the ceiling 2 </ b> A by high-frequency induction heating can be used. The induction coil 5 is disposed outside the chamber 2 so as to be opposed to the lower surface 4b of the mounting plate and the upper surface of the ceiling 2A, respectively.

  In the manufacturing apparatus 1, when a high frequency current is supplied to the induction coil 5 from a high frequency power supply (not shown), the mounting plate 4, the wafer support 3, the sealing 2A, and the peripheral wall 2B are heated by high frequency induction heating. The SiC wafer W placed on the wafer support 3 can be heated by radiation from the mounting plate 4, the ceiling 2 </ b> A, the peripheral wall 2 </ b> B, heat conduction from the wafer support 3, or the like.

  As the mounting plate 4, the sealing 2 </ b> A, and the peripheral wall 2 </ b> B, a material made of a graphite (carbon) material having excellent heat resistance and good thermal conductivity can be used as a material suitable for high-frequency induction heating. Furthermore, in order to prevent generation of particles or the like from graphite (carbon), a material whose surface is coated with SiC, TaC or the like can be suitably used.

  The temperature raising means is not limited to the above-described high-frequency induction heating, but may be resistance heating or the like. Further, the temperature raising means is not limited to the configuration disposed on both the lower surface side 4b of the mounting plate and the upper surface side of the ceiling 2A, and may be configured to be disposed only on either one of these. .

  As means (gas supply means) for supplying the source gas G to the reaction space K, for example, as shown in FIG. 1, a gas introduction pipe (gas) for introducing the source gas G into the reaction space K from the center of the upper surface of the ceiling 2A. Inlet 6) can be used. The gas introduction pipe 6 is formed in a cylindrical shape, and is arranged with its tip (lower end) facing the reaction space K in a state of passing through a circular opening 13 provided at the center of the ceiling 2A. ing.

  In the manufacturing apparatus 1, the source gas G discharged from the gas introduction pipe 6 flows radially from the inner side to the outer side of the reaction space K, and is supplied in parallel to the in-plane of the SiC wafer W. It is configured as follows. The gas that is no longer necessary in the chamber can be discharged out of the chamber through an exhaust port (not shown) provided outside the peripheral wall 4.

  Since the sealing 2A is heated at a high temperature by the induction coil 5, a gas introduction pipe 6 that is cooled to introduce the raw material gas G at the inner periphery (the center where the opening 13 is formed) Is contactless.

  In the epitaxial wafer manufacturing apparatus 1 to which the present invention is applied, particles approaching the surface to be processed of the wafer are separated from the flow path of the second gas for rotating the SiC wafer W in order to make the crystal film formation of the SiC wafer W uniform. The first gas flow path for purging (or blocking) is provided. Therefore, the first gas is supplied from a different flow path from the second gas. Therefore, it becomes possible to flow the first gas independently of the second gas.

  Then, it is possible to prevent the particles from approaching the surface to be processed of the wafer by flowing the first gas without rotating the wafer support table. With this rotation, the wafer support table 3 and the mounting plate 4 It is possible to prevent generation of particles due to rubbing, and to prevent occurrence of displacement of the SiC wafer W with respect to the wafer support 3.

  Alternatively, even if the wafer support is configured to rotate by flowing a rotating gas, it is not necessary to increase the flow rate of the rotating gas from the flow rate during crystal growth in order to increase the purge effect or blocking effect. The purge effect or blocking effect can be enhanced by flowing the first gas without increasing the generation of particles due to friction between the wafer support and the mounting plate, and without increasing the occurrence of displacement of the SiC wafer.

  In addition, in order to increase the purge effect or blocking effect at the time of temperature rise, it is not necessary to increase the flow rate of the rotating gas from the flow rate during crystal growth, so it is necessary to return the flow rate of the rotating gas to the flow rate during crystal growth immediately before crystal growth. There is no significant change in the temperature of the SiC wafer before and after crystal growth.

  In the type of apparatus in which the rotating gas flows out of the chamber, even when Ar (argon) gas is used as the rotating gas, the Ar gas is not mixed into the hydrogen gas of the carrier gas. Therefore, the formation of Si (silicon) droplets in the chamber can be prevented, and the problem of generation of defects (shallow pits) in the epitaxial film caused by the Si droplets can be avoided.

(Epitaxial wafer manufacturing method)
The first embodiment of the method for manufacturing an epitaxial wafer to which the present invention is applied is a method including a step of depositing and growing an epitaxial layer on the surface of the SiC wafer W using the manufacturing apparatus 1 described above.

  First, a SiC wafer W is produced or prepared. The SiC wafer W is obtained by slicing a SiC ingot produced using a sublimation recrystallization method or the like into a disk shape and then polishing the surface thereof.

  Then, in the chamber 2, the SiC wafer W is placed on the wafer support 3 and heated in a stationary state (heating process). As shown in FIG. 1, the heating in the heating process can be performed outside the chamber 2 by using induction coils 5 that are arranged opposite to each other in close proximity to the lower surface 4 b of the mounting plate and the upper surface of the ceiling 2. Specifically, the mounting plate 4, the wafer support 3, the ceiling 2 </ b> A, and the peripheral wall 2 </ b> B are heated by high-frequency induction heating generated by supplying a high-frequency current to the induction coil 5. Thereby, the SiC wafer W placed on the wafer support 3 can be heated by radiation from the mounting plate 4, the ceiling 2 </ b> A, the peripheral wall 2 </ b> B, heat conduction from the wafer support 3, or the like.

  In the first step, the first gas G1 is directed from the inflow hole 10a provided around the wafer support 3 into the chamber 2 so as to prevent the particles P from approaching the surface Wa of the SiC wafer. Inflow. As the first gas G1, it is preferable to use a gas containing a heavy element such as argon (Ar).

Subsequently, the source gas G is supplied into the chamber 2, and the wafer support 3 and the SiC wafer W placed thereon are used with the second gas G 2 so that the film is uniformly formed in the plane. An epitaxial wafer is obtained by depositing and growing an epitaxial layer on the surface of the SiC wafer W (growth step) while rotating. The rotation of the SiC wafer W is preferably performed so that the direction of the normal of the surface is substantially constant. As the second gas G2, it is preferable to use a gas composed of hydrogen molecules (H ₂ ) contained in the source gas G.

  In the method for manufacturing an epitaxial wafer to which the present invention is applied, the first gas G1 for purging (or blocking) particles approaching the surface to be processed of the wafer is used for the SiC wafer in order to uniformize the film formation of the SiC wafer. The gas is introduced by means independent of the second gas G2 that rotates the gas. Therefore, since the first gas is supplied from a flow path different from that of the second gas, the first gas G1 is introduced into the reaction space K without rotating the wafer support 3 and the surface to be processed of the wafer. It is possible to prevent particles from approaching. For this reason, there is no possibility of generation of particles due to friction between the wafer support base and the mounting plate, and displacement of the SiC wafer relative to the wafer support base due to rotation.

  Alternatively, even if the wafer support is rotated by flowing a rotating gas, it is not necessary to increase the flow rate of the rotating gas from the flow rate during crystal growth in order to increase the purge effect or blocking effect. The purge effect or the blocking effect can be enhanced by flowing the first gas without increasing the generation of particles due to friction with the mounting plate and without increasing the occurrence of displacement of the SiC wafer.

  Further, since it is not necessary to increase the flow rate of the rotating gas more than the flow rate at the time of crystal growth in order to enhance the purge effect or the block effect at the time of temperature rise, the temperature of the SiC wafer does not change greatly.

  Therefore, according to the epitaxial wafer manufacturing method of the present invention, the generation of particles due to the friction between the wafer support 3 and the mounting plate 4 caused by the rotation of the wafer support 3 when the temperature is raised, the wafer support 3 There is no possibility that the position of the SiC wafer W is displaced relative to the surface.

  In addition, according to the epitaxial wafer manufacturing method of the present invention, a part of the heat of the wafer support 3 is not lost by the rotation during the temperature rise, so that the temperature in the surface of the SiC wafer W is set to a predetermined value. It is possible to adjust the temperature (deposition temperature).

  In the epitaxial wafer manufacturing method to which the present invention is applied, it is possible to stably deposit and grow a high-quality SiC epitaxial layer on the surface of the SiC wafer W by using the manufacturing apparatus 1. Since the time required for maintenance of the manufacturing apparatus 1 can be shortened, the product yield of the epitaxial wafer can be further improved.

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus, 2 ... Chamber, 3 ... Wafer support stand, 4 ... Mounting plate,
4a ... one surface (upper surface), 8 ... concave portion, 10 ... first flow path,
10a, 11a ... one end, 10b, 11b ... the other end,
11 ... 2nd flow path, 15 ... Rotating gas exhaust hole, G ... Raw material gas,
G1 ... first gas, G2 ... second gas, L ... gap, P ... particles,
W: Wafer (SiC wafer), Wa: Surface to be processed.

Claims (8)

An epitaxial wafer manufacturing apparatus for depositing and growing an epitaxial layer on a heated wafer surface while supplying a source gas into a chamber,
In the chamber,
A mounting plate provided with a recess on one side;
Between the inner wall surface of the concave portion, with a gap so as to be rotatable, and at least a wafer support base accommodated in the concave portion,
The mounting plate is
A first flow path having one end on the inner wall surface of the recess, connected to the reaction space in the chamber through the gap, and flowing a first gas that prevents particles from approaching the surface to be processed of the wafer When,
And a second flow path having one end on the inner wall surface of the recess, connected to the gap, and flowing a second gas for rotating the wafer together with the wafer support. Epitaxial wafer manufacturing equipment.   The epitaxial wafer manufacturing apparatus according to claim 1, wherein one end of the first flow path is connected to an inner bottom surface of the inner wall surface of the recess.   One end of the first flow path is provided at an upstream and / or downstream position when the source gas flows into the chamber, at least on the inner wall surface of the recess. The epitaxial wafer manufacturing apparatus according to claim 1 or 2.   On the inner wall surface of the recess, a rotary gas discharge hole penetrating the inside of the mounting plate is provided from a position between one end of the first flow path and one end of the second flow path. The epitaxial wafer manufacturing apparatus according to any one of claims 1 to 3, wherein: An epitaxial wafer manufacturing method in which an epitaxial layer is deposited and grown on the surface of a heated wafer while supplying a source gas into the chamber,
A growth step of depositing and growing the epitaxial layer on the surface of the wafer while rotating the wafer support and the wafer placed thereon using a second gas;
Before the growth step, the first gas that flows upward through the side surface of the wafer is flowed using a flow path that is provided separately from the flow path through which the second gas flows. Production method.   The epitaxial wafer manufacturing method according to claim 5, wherein a gas containing an argon element is used as the first gas.   The method for manufacturing an epitaxial wafer according to claim 5 or 6, wherein a gas comprising a hydrogen element is used as the second gas.   6. The method for manufacturing an epitaxial wafer according to claim 5, wherein a gas containing a hydrogen element is used as the first gas, and a gas containing an argon element is used as the second gas.

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