JP5191373B2 - Epitaxial wafer manufacturing method and manufacturing apparatus - Google Patents

Description

  The present invention relates to a method and apparatus for manufacturing an epitaxial wafer used for semiconductor integrated circuit elements and the like, and more particularly, to a method and apparatus for manufacturing an epitaxial wafer that performs temperature ordering in a wafer heating process before an epitaxial growth process.

  The trend toward higher density of integrated circuit elements (devices) using silicon semiconductors is rapidly progressing, and the requirements for the quality of silicon wafers that form devices are becoming increasingly severe. In other words, the higher the integration density, the more delicate the circuit, and crystal defects such as dislocations that cause an increase in leakage current and a reduction in carrier lifetime are much more severely limited than before.

  Based on the epitaxial manufacturing apparatus 100 shown in FIG. 10, the manufacturing method of an epitaxial wafer is demonstrated easily. First, the silicon single crystal substrate 12 is placed on the susceptor 14. The susceptor 14 is rotatably supported by the support member 161. Further, the placed silicon single crystal substrate 12 is supported at the time of placing by a lift supporting member 163 provided with a vertically extending lift member at the end. The silicon single crystal substrate and peripheral parts are cleaned by allowing carrier gas or the like to flow into the chamber containing the transparent window member 150 on the upper surface from the inlet 168 and out of the outlet 170. Next, if necessary, the silicon single crystal substrate 12 is heated by the upper heaters 16a and 16a and the lower heaters 16b and 16b to perform heat treatment. At this time, in order to increase the thermal efficiency, reflectors 18a and 18b are respectively arranged on the back surfaces of the upper heaters 16a and 16a and the lower heaters 16b and 16b. Moreover, the cover 190 which covers the whole also functions as a reflector. The temperature of the silicon single crystal substrate 12 is monitored by a radiant heat thermometer 32 provided at the top, and the temperature of the back surface of the susceptor 14 is monitored by a radiant heat thermometer 34 provided below. Then, a gas serving as a silicon source such as silane or trichlorosilane is introduced from the introduction port 168 together with a carrier gas, and the main surface of the silicon single crystal substrate 12 is exposed at about 800 ° C. or higher, and the main surface is exposed. An epitaxial layer of silicon is grown on (hereinafter, the silicon single crystal substrate and the silicon epitaxial wafer are collectively referred to as a silicon wafer). After the epitaxial layer having a predetermined thickness is grown, the supply of the source gas is stopped, the temperature of the silicon wafer on which the epitaxial layer is stacked is lowered, taken out from the chamber, and supplied to the next step. In this series of manufacturing processes, great care is taken not to cause crystal defects such as contamination and dislocations.

  The heat treatment step before the epitaxial layer growth step does not directly affect the growth of the epitaxial layer, but is important for obtaining desirable silicon wafer characteristics. In this heat treatment step performed at a temperature equal to or higher than the temperature in the epitaxial layer growth step in a non-oxidizing atmosphere such as hydrogen or argon, in the temperature rising step at 700 ° C. or higher, removal of defects in the silicon wafer and thermal stress, In order to increase productivity while preventing the occurrence of dislocation due to contact stress or the like, a high temperature rising rate is desired. However, when the temperature gradient between the main surface and the back surface of the silicon wafer becomes steep, the silicon wafer may be warped, and even if no warpage occurs, crystal defects called slip dislocations are present in the wafer. Since it may occur, temperature control in temperature rise and fall is also important.

  On the other hand, since the growth of the epitaxial layer is greatly influenced by the temperature, temperature management within the surface of the silicon wafer is important (for example, Patent Document 1). Therefore, even with a single-wafer vapor phase thin film growth apparatus that has been devised in terms of structure and materials, there is a difference in the thickness of the epitaxial layer depending on the in-plane position of the silicon wafer. In particular, the thickness of the silicon epitaxial layer is about 8 μm. In the case of exceeding, the difference in the in-plane thickness of the silicon epitaxial layer tends to be emphasized to a practically unfavorable level. Therefore, it has been proposed to improve the shape of the support means made of quartz, omit the central vertical pin, and shift the contact position of the support member to the back surface of the susceptor to the outer peripheral side (for example, Patent Document 2). .

By the way, in the semiconductor wafer manufacturing method including the step of heat-treating the semiconductor wafer at a predetermined temperature using an RTA apparatus, the temperature of the contact portion of the semiconductor wafer with at least the support jig for supporting the semiconductor wafer is at the center of the semiconductor wafer. A technique is disclosed in which heat treatment is performed in a state controlled to be 3 to 20 ° C. lower than the temperature to suppress the occurrence of slip dislocation (Patent Document 2).
JP 2003-133239 A JP 2000-103696 A

  However, in the temperature measurement of Patent Document 1, even if the temperature difference can be measured, a method for correcting the temperature difference is re-installation of the silicon single crystal substrate, and it is difficult to obtain an industrially sufficient effect. In addition, in the roughness measurement of Patent Document 2, although only good products can be selected, the measurement itself cannot increase the good product rate, and in order to make the temperature distribution uniform, a central vertical pin is used. By omitting and shifting the contact position of the support member to the back surface of the susceptor to the outer peripheral side, it is difficult to improve the dynamic temperature state of temperature increase or decrease even if the static temperature state can be improved. is there.

  Therefore, the present inventors have clarified a thermal state including a temperature rise or a temperature drop in an epitaxial wafer manufacturing method in which an epitaxial layer is grown on the main surface of a silicon single crystal substrate, and a preferable static related to a jig used in a manufacturing apparatus. The present invention provides a method and an apparatus for manufacturing an epitaxial wafer in which improvement and dynamic improvement of heating are added and they are fused.

  In view of the above problems, in an epitaxial wafer manufacturing apparatus for growing an epitaxial layer on the main surface of a silicon single crystal substrate disposed in a substantially horizontal state on a susceptor, at least on the silicon single crystal substrate. Or a heater disposed underneath, a reflector disposed behind the heater as viewed from the silicon single crystal substrate, and a control device capable of controlling the output of the heater, the reflector from the heater The heater includes an inclined portion corresponding to the inclined portion, and the controller includes an inclined portion corresponding to the inclined portion so as to reflect more heat rays at a center side of the silicon single crystal substrate at a predetermined ratio. Provided is a manufacturing apparatus capable of controlling the output of the heater element corresponding to the inclined portion according to the ratio of the inclined portion, and a manufacturing method thereof. .

More specifically, the following can be provided.
(1) An epitaxial wafer manufacturing apparatus for growing an epitaxial layer on a main surface of a silicon single crystal substrate disposed substantially horizontally on a susceptor, which is disposed at least above or below the silicon single crystal substrate. Heater, a reflector disposed behind the heater as viewed from the silicon single crystal substrate, and a control device capable of controlling the output of the heater, wherein the reflector transmits the heat rays from the heater Inclined portions inclined so as to reflect more on the center side of the silicon single crystal substrate are provided at a predetermined ratio, the heater includes an inclined portion corresponding heater element corresponding to the inclined portion, and the control device includes the inclined portion. The epitaxial wafer manufacturing apparatus is characterized in that the output of the heater element corresponding to the inclined portion is controlled in accordance with the ratio of Kill.

  Here, “substantially horizontal” may be horizontal so long as the mounted silicon single crystal substrate does not move under its own weight. Therefore, strict horizontality is not required. It is more preferable that the level is as high as that obtained by a general level. The heater is preferably a heater that emits heat rays. For example, a lamp heater, an infrared lamp, a halogen lamp, etc. can be mentioned as examples. The reflector may be anything that substantially reflects heat rays (eg, may include visible light, infrared light, far infrared light, etc.). For example, an aluminum alloy coated with gold may be included. The reflector is usually provided behind the heater, and reflects the heat rays radiated backward, more preferably by a parabolic curved surface, and radiates forward. The reflector reflects incident light according to the law of reflection, but if the incident light illuminates the reflector uniformly at all angles (assuming a flat reflecting surface, not a curved surface here), the reflected light is the same as well. It can be reflected uniformly at all angles. However, when the reflector is provided at an angle, the incident light does not necessarily irradiate the reflector uniformly, and as a result, the reflected light may reflect more heat rays in a biased direction. is there. In addition, when the reflecting surface of the reflector spreads evenly with respect to the heater (the reflecting surface of the reflector receives the heat rays so that the heat rays are evenly radiated and not biased), the reflected light becomes more heat rays in the biased direction. Instead of being reflected, it is reflected uniformly in all directions (theoretically π radians in solid angles) (at least in the range of symmetry when reflectors and heaters are provided symmetrically). Therefore, in order to reflect more on the center side, the inclination angle is set to an angle that more faces (or faces) the irradiation object (for example, the center). In addition, when the reflector receives only a part of the heat rays radiated from the heater as incident light, it receives light radiated in a predetermined angle range from the heater, so that the deviation of the incident angle range, and / or As the amount of heat rays per unit area on the reflecting surface is biased, more heat rays can be reflected in the biased direction (range) than in other directions (range). For example, a silicon single crystal substrate or susceptor disposed substantially horizontally is similarly disposed substantially horizontally, and a reflector facing the silicon single crystal substrate or susceptor is between and closer to the reflector. When light from a heater arranged at a position (for example, 10% or less, 5% or less, 1% or less, etc. of the facing distance) is reflected, the reflected light is relatively reflected on these facing silicon single crystal substrates and susceptors. Uniform irradiation. However, when facing each other with a slight tilt angle, even if the light is uniformly emitted from the heater at all angles, the light incident on the reflecting surface of the reflector may be biased. It is considered that the heat ray is reflected at a higher rate on the inclined side. An inclined part including such an inclined reflecting surface can be provided at a certain ratio with respect to the entire reflector made of the reflecting surface of the reflector spreading like a donut. This ratio can be defined by an area assuming the flat surface of the reflecting surface of the inclined portion with respect to the entire area of the reflecting surface of the reflector assuming a flat surface (or a horizontal surface). At this time, the reflecting surface of the reflector that is sufficiently far away from the heater (for example, 10 times, 20 times, 50 times or more of the distance from the nearest reflecting surface) can be ignored. Moreover, it is preferable to provide such an inclined part (and its reflecting surface) in rotational symmetry with respect to a central axis standing perpendicular to the center of the donut (in many cases, the center of the silicon wafer).

(2) Further, a wafer thermometer for measuring the temperature of the silicon single crystal substrate, and a susceptor thermometer for measuring the temperature of the susceptor, wherein the control device The apparatus for producing an epitaxial wafer according to (1) above, wherein the output of the heater element corresponding to the inclined portion is controlled so that the difference from the temperature of the susceptor is 10 ° C. or less. .

  Here, the difference between the temperature of the silicon single crystal substrate and the temperature of the susceptor is preferably 10 ° C. or less, more preferably 5 ° C. or less, and further preferably 3 ° C. or less.

(3) When the predetermined ratio is 60% or more with respect to the reflector, the control device sets the output ratio of the output corresponding to the inclined portion heater element to 60% or less, and outputs the entire output as necessary. The epitaxial wafer manufacturing apparatus according to (1) or (2) above, wherein the silicon single crystal substrate is heated to a desired temperature by increasing or decreasing the value.

  Here, the predetermined ratio is preferably 60% or more, more preferably 65% or more, and further preferably 70% or more. At this time, the output ratio of the output of the heater element corresponding to the inclined portion is preferably 60% or less, more preferably 50% or less, and further preferably 45% or less. Further, the desired temperature can mean, for example, a temperature (and its range) preferable for growing an epitaxial film. This temperature may include the pre-growth emperor where the epitaxial film is not actually grown and the temperature in the temperature hold / cooling process after growth.

(4) A method for manufacturing an epitaxial wafer, wherein an epitaxial layer is grown on a main surface of a silicon single crystal substrate disposed substantially horizontally on a susceptor, wherein the epitaxial layer is grown at least above or below the silicon single crystal substrate. A step of heating the silicon single crystal substrate to a predetermined temperature in a non-oxidizing atmosphere by means of a heater disposed in the furnace, a step of cooling the heated silicon single crystal substrate to a predetermined epitaxial growth temperature, and the silicon single crystal Including any step of growing an epitaxial layer on the main surface of the substrate at a predetermined temperature, and cooling the epitaxial wafer on which the epitaxial layer is grown on the main surface of the silicon single crystal substrate. The difference between the temperature of the silicon single crystal substrate and the temperature of the susceptor is 10 ° C. or less. And a reflector disposed behind the heater as viewed from the silicon single crystal substrate is inclined so as to reflect more heat rays from the heater toward the center side of the silicon single crystal substrate. The epitaxial device is provided with a predetermined ratio, and the heater includes an inclined portion corresponding heater element corresponding to the inclined portion, and controls the output of the inclined portion corresponding heater element according to the ratio of the inclined portion. A method for manufacturing a wafer can be provided.

(5) When the predetermined ratio is 60% or more with respect to the reflector, the output ratio of the output corresponding to the inclined portion heater element is set to 60% or less, and the overall output is increased or decreased as necessary. The method for producing an epitaxial wafer as described in (4) above, wherein the silicon single crystal substrate is controlled to have a desired temperature.

  According to the present invention, the temperature difference between the silicon wafer and the susceptor generated in the heating and cooling step and the predetermined temperature holding step (for example, epitaxial growth step) is controlled to be within a predetermined range, and the in-plane of the silicon wafer is controlled. It is possible to easily control the variation of the temperature distribution so as to be within a predetermined range. In particular, by tilting a predetermined portion of the reflector disposed behind the optical heater at a predetermined angle, a preferable silicon wafer without dislocation can be manufactured in a wide output range of the heater. Here, the temperature difference within a predetermined range can mean, for example, a temperature difference range in which defects such as dislocations hardly occur in a silicon wafer. Moreover, the variation in temperature distribution within a predetermined range can mean, for example, a range of variation in temperature distribution in which defects such as dislocations hardly occur in a silicon wafer.

  Next, embodiments of the present invention will be described with reference to the drawings. In the drawings, components having the same configuration or function and corresponding parts are denoted by the same reference numerals, and description thereof is omitted. Moreover, in the following description, the example of the embodiment which concerns on this invention is shown, and it can change suitably based on the technical common sense of those skilled in the art, without exceeding the range of this invention. Therefore, the scope of the present invention is not limited to these specific examples. Also, these drawings are emphasized for the purpose of explanation, and may differ from actual dimensions.

  FIG. 1 is a schematic diagram of an epitaxial wafer manufacturing apparatus according to an embodiment of the present invention. Basically, the configuration is almost the same as that of the epitaxial wafer manufacturing apparatus of FIG. Cylindrical reflectors 20a and 20b are provided in the center above and below the silicon wafer, respectively, to prevent heating of the rotating shaft and to secure an optical path for temperature measurement. In addition, the reflectors 18a and 18b arranged on the rear surfaces of the heaters 16a, 16a, 16b and 16b made of halogen lamps or the like reflect more heat toward the center of the silicon wafer 12 at a predetermined ratio. An inclined slope is provided. An inclined portion corresponding heater element corresponding to the inclined portion is provided.

  FIG. 2 is a plan view showing a radial arrangement of halogen lamps 16-01 to 20 which are heater elements of the heater. A circular space in which the reflectors 20a and 20b can be arranged is provided in the center, and 20 halogen lamps are arranged clockwise around the periphery. On the lower side, a reflector 18 (18a in the upper case and 18b in the lower case) is provided. In the figure, a first group consisting of halogen lamps 16-01, 02, 06, 07, 11, 12, 16, 17 and a first group consisting of halogen lamps 16-03 to 05, 08 to 10, 13 to 15, and 18 to 20 are shown. It was divided into two groups, and two types of reflectors having inclined portions corresponding to each group were prepared. The first reflector is provided with an inclined portion in the first group, and the second reflector is provided with an inclined portion in the second group. Therefore, in the 1st reflector, an inclined part is provided in the ratio of 2: 3, and in an 2nd reflector, an inclined part is provided in the ratio of 3: 2. Each inclined portion is inclined at a predetermined angle (for example, 7 degrees) so as to reflect more heat rays toward the central portion of the silicon wafer 12 of FIG.

FIG. 9 illustrates this inclination angle. The vertical distances from the reflectors 18a, 18b to the silicon wafer 12 (particularly from the radial centers 16a-c, 16b-c of the reflectors) are defined as H _a , H _b , and silicon in the plane where the reflectors 18a, 18b are placed If the distance to the center corresponding to the center of the wafer 12 is L _a and L _b , then Δ _a = tan ⁻¹ (H _a / L _a ) and Δ _b = tan ⁻¹ (H _b / L _b ). It is. Here, the predetermined angle alpha _a, alpha _b is _{0 <α a <π / 2} -Δ a, is _{0 <α b <π / 2} -Δ b. Here, when the height is relatively large, Δ _a and Δ _b increase, so it is considered that the inclination angle does not need to be increased so much, and α _a and α _b tend to decrease. On the other hand, when the height is relatively small, Δ _a and Δ _b are small, so it is considered that the inclination angle does not need to be so small, and α _a and α _b tend to increase. In normal H _a / L _a and H _b / L _b , the inclination angles α _a and α _b are each preferably 2 degrees or more, more preferably 4 degrees or more, and further preferably 5 degrees or more. Further, the inclination angles α _a and α _b are each preferably 12 degrees or less, more preferably 10 degrees or less, and still more preferably 8 degrees or less. Approximately 7 degrees is considered preferable. Note that the inclination angles α _a and α _b need not be the same. It can select suitably according to arrangement | positioning of each apparatus of an apparatus. Here, L _a and L _b may mean distances from the center position to the center in the radial direction of the halogen lamp. Moreover, when these numerical values are not the same, it can obtain | require by arithmetic mean. Since the silicon wafer 12 and the susceptor 14 to be heated rotate around the same central axis, they are uniformly heated by the heater provided for the rotation target in this way.

  FIG. 3 shows temporal changes in the temperature of the silicon wafer and the output of each heater (heater element) when an epitaxial wafer is manufactured by providing the first reflectors at the top and bottom with the apparatus of FIG. First, up to an arbitrary unit of time 2, the silicon wafer (silicon single crystal substrate) was heated by the upper and lower halogen lamps to perform heat treatment. The maximum temperature reached was 5 in arbitrary units. That is, the average heating rate was about 5/2 = about 2.5. Next, the output of the heater was weakened and cooled to enter the epitaxial growth process. Here, first, the temperature of the silicon wafer was set to an arbitrary unit of temperature 4, and then a raw material gas having a predetermined concentration was flowed and epitaxial growth was performed from an arbitrary unit of time 2.5 to 4.5 while rotating. Next, the heater output was minimized and allowed to cool.

The epitaxial growth conditions at this time are described below. This condition was the same in the epitaxial manufacturing method described below.
Carrier gas Hydrogen Source gas 5% silane or trichlorosilane
Flow rate 50 liters / minute with mixed gas

  FIG. 4 shows changes over time in the temperature of the silicon wafer and the output of each heater (heater element) when an epitaxial wafer is manufactured by providing the second reflectors at the top and bottom with the apparatus of FIG. Since the temperature and time in arbitrary units in this figure are the same as those in FIG. 3, they can be directly compared. Compared to the case of FIG. 3, the time until the maximum temperature reached 5 was about 1.4, and the average rate of temperature increase was about 5 / 1.4 = about 3.6. For this reason, the heat treatment time at temperature 5 could be maintained for a longer period.

  Tables 1 and 2 summarize the experimental results, including the experiments of FIGS. FIG. 3 is the one of 50/50/50 in Table 1. The dislocation free (no dislocation) wafer was only when the temperature difference between the upper surface and the lower surface was −25 or −30. Here, 50/50/50 is that the output ratio of the upper and lower heaters is 50% each (first 50), and the output ratio of the heater corresponding to the inclination corresponding to the upper inclined portion and the other heaters is 50%. (The next 50), and the output ratio of the heater corresponding to the inclination corresponding to the lower inclined portion and the other heaters is 50% (the last 50). On the other hand, FIG. 4 is the one of 50/60/60 in Table 2, and the dislocation-free (no dislocation) wafer was only when the temperature difference between the upper surface and the lower surface was −30. Thus, despite the fact that almost the same dislocation-free state can be obtained, the second reflector can obtain the effect of taking a long heat treatment time and shortening the treatment time.

Here, in Table 1, when the temperature difference between the upper surface and the lower surface is large, dislocation is likely to occur, but this is because the temperature difference between the upper surface and the lower surface is increased because the rate of temperature increase is slowed. That is, in Table 1, as the temperature difference increases, the temperature rising rate decreases. Moreover, in the 1st reflector, since the radiation | emission ratio of the heat | fever to an outer periphery is high, if an inner side output is enlarged, an output will decline on the whole, and a temperature increase rate will fall. For this reason, the area that is likely to be dislocation free has increased. On the other hand, in Table 2, similarly, when the temperature difference between the upper surface and the lower surface is large, dislocation is likely to occur. This is because the temperature difference between the upper surface and the lower surface is increased as a result of similarly decreasing the temperature increase rate. That is, in Table 2, as the temperature difference increases, the temperature rising rate decreases. However, in the second reflector, since the radiation ratio of heat to the outer periphery is low , when the output on the inner side is increased, the output increases as a whole and the temperature raising rate is increased. As a result, the area that is likely to be dislocation free has decreased.

  5A to 5C are plots of 50/40/40 (a), 50/50/50 (b), and 50/60/60 (c) of Table 1, respectively. When the output ratio of the heater element corresponding to the inclination is as low as 40% (a), it can be seen that the temperature distribution varies particularly in the outer peripheral portion. Moreover, although the temperature difference was substantially zero in the central part, the difference was also observed in the plane at approximately 10 ° C. in the outer peripheral part. Even in the case where the output ratio of the heater element corresponding to the inclination is about 50% (b), the temperature distribution in the outer peripheral portion varies although it is smaller than that in (a). In addition, although the temperature difference is almost zero in the central portion, there is a slight difference even in the plane at about 5 ° C. in the outer peripheral portion. Even when the output ratio of the heater element corresponding to the inclination is as high as 60%, the temperature distribution in the outer peripheral portion is slightly varied, although it is considerably smaller than that in (a). The temperature difference was almost zero at the center, and the in-plane difference was reduced to several degrees C. at the outer periphery. As a result, it can be seen that when the temperature difference at the outer peripheral portion is particularly small, the rate of temperature increase is low and the dislocation-free region becomes large.

  6A to 6C are plots of 50/40/40 (a), 50/50/50 (b), and 50/60/60 (c) of Table 2, respectively. From these figures, it can be seen that when the output ratio of the inclination corresponding heater element is as low as 40% (a), the temperature distribution in the intermediate portion varies. Further, although the temperature difference is almost 0 in the central portion, the difference in the plane is about 5 ° C. in the middle portion and about 2-3 ° C. in the outer peripheral portion, which is smaller than that in the case of FIG. However, the in-plane temperature difference is the largest in FIG. Even if the output ratio of the heater element corresponding to the inclination is about 50% (b), although it is less than (a), it is scattered around 2 to 3 ° C in the middle part, but the temperature difference in the outer part There was almost no variation. Therefore, the variation in the in-plane temperature difference distribution was not so large. When the output ratio of the heater element corresponding to the inclination is as high as 60%, the temperature distribution in the middle part is slightly different in (c) although it is considerably smaller than (a) and (b). Although the temperature difference is substantially zero at the center, the temperature difference is reversed at the outer periphery at a minus several degrees Celsius. Thus, it can be seen that in any of the outer peripheral portions, the temperature difference and the variation in the temperature difference are small, and the dislocation-free region is larger in the case of (a) where the rate of temperature increase is low.

  FIG. 7 shows the upper heaters 16a and 16a and the lower heaters 16b and 16b for heating the silicon wafer 12 and the susceptor 14, and the respective reflectors 18a and 18b on the rear surface and the cylindrical center in the epitaxial wafer manufacturing apparatus 210. The reflectors 20a and 20b are schematically shown, and the movement of heat is explained by the heat rays 200a and 200b. Heat rays are radiated from the upper and lower heaters 16a, 16a, 16b, and 16b so as to spread from each light emitting point to a hemispherical surface. Since each of these heat rays represents approximately the same amount of heat, the more heat rays hit, the more heat moves. Heat rays 200a, 200b radiate from the surfaces of the upper and lower heaters 16a, 16a, 16b, 16b facing the silicon wafer 12 and the susceptor 14, and heat is transferred to the surface of the silicon wafer 12, the upper surface and the bottom surface of the susceptor 14. . Further, the heat rays hitting the cylindrical portions 21a and 21b and the cone portions 22a and 22b of the reflectors 20a and 20b are reflected according to the law of the reflection angle, and the reflected heat rays carry almost the same amount of heat, and heat is applied to the portion where the reflected heat rays hit. Tell. Accordingly, the amount of heat input from the silicon wafer 12 is almost determined by the number of heat rays hitting its main surface, and the susceptor 14 flows in at the outer edge of the upper surface (outside of the silicon wafer 12) and by the number of heat rays hitting the entire bottom surface. The amount of heat is almost determined.

FIG. 8 is a diagram schematically showing how the heat rays radiated from the back side of the upper and lower heaters 16 a, 16 a, 16 b, and 16 b are reflected by the reflector 18. FIG. 8A schematically shows the state of reflection at the reflector 18 arranged in a normal horizontal direction, and FIG. 8B schematically shows the state of reflection at the inclined portion 19 provided at a predetermined ratio. is there. As described above, light emitting heat rays are emitted hemispherically from each bright spot 161 on the side surface of the silicon wafer 12 of the heater 16, and light is similarly emitted from each bright spot 162, 163 on the back side as viewed from the silicon wafer 12 side. Heat rays are emitted. It can be seen that each heat ray is reflected by the surface 164 of the normal reflector 18 and spreads almost evenly. On the other hand, since the surface 165 of the inclined portion 19 is reflected by being inclined by the inclination angle β, it can be seen that more heat rays are reflected toward the center portion (right side in the drawing) of the silicon wafer 12. Accordingly, at each of the bright spots 162 and 163 on the rear surface as viewed from the silicon wafer 12, the heat rays emitted at an angle θ with respect to the surface are reflected at an angle of π−θ + 2 × β with respect to the surface. It will be. These relationships are represented by mathematical formulas.
Reflection angle (normal) = π−θ (Formula 1)
Reflection angle (tilt angle β) = π−θ + 2 × β (Formula 2)

It is the schematic which shows the positional relationship of the heater and reflector in an epitaxial wafer manufacturing apparatus, a silicon wafer, and a susceptor. It is a top view which shows arrangement | positioning of the halogen lamp which is each heater element of a heater. It is a graph which shows the time-dependent change of the temperature and heater output in the epitaxial wafer manufacturing method at the time of using a 1st reflector. It is a graph which shows the time-dependent change of the temperature and heater output in the epitaxial wafer manufacturing method at the time of using a 2nd reflector. The temperature distribution in the wafer in the 50/40/40, 50/50/50, and 50/60/60 epitaxial wafer manufacturing method of Table 1 is plotted, respectively. The temperature distribution in the wafer in the 50/40/40, 50/50/50, and 50/60/60 epitaxial wafer manufacturing method of Table 2 is plotted, respectively. It is a figure which shows the upper part and the lower heater which heat a silicon wafer and a susceptor, and a reflector and a cylindrical reflector on a back surface, and demonstrates the movement of the heat | fever by a heat ray. It is a figure which shows typically how the heat ray radiated | emitted from the back side of an upper part and a lower heater is reflected in a reflector. In the epitaxial wafer manufacturing apparatus of FIG. 1, it is the schematic explaining the inclination-angle of a reflector. It is a schematic sectional drawing which shows an epitaxial wafer manufacturing apparatus.

Explanation of symbols

100, 210 Epitaxial wafer manufacturing apparatus 12 Silicon wafer 14 Susceptors 16, 16a, 16b Halogen lamps 18, 18a, 18b Reflector 19 Inclined portions 20a, 20b Cylindrical reflectors 32, 34 Radiant heat thermometer

Claims (2)

An epitaxial wafer manufacturing apparatus for growing an epitaxial layer on a main surface of a silicon single crystal substrate disposed substantially horizontally on a susceptor,
A heater arranged radially from the center of the silicon single crystal substrate in a plan view above and / or below the silicon single crystal substrate;
A reflector disposed rotationally symmetrically with respect to a central axis standing perpendicular to the center of the silicon single crystal substrate behind the heater as viewed from the silicon single crystal substrate;
A wafer thermometer for measuring the temperature of the silicon single crystal substrate;
A susceptor thermometer for measuring the temperature of the susceptor;
A control device capable of controlling the output of the heater,
The reflector is inclined so as to reflect heat at a higher rate than the outer peripheral portion of the silicon single crystal substrate toward the central portion of the silicon single crystal substrate in response to heat rays emitted backward from the heater. Provide the sloped part at a rate of 60% or more ,
The heater includes an inclined portion corresponding heater element corresponding to the inclined portion,
The control device sets the output ratio of the heater element corresponding to the inclined portion to 60% or less, and increases or decreases the total output as necessary, thereby measuring the temperature of the silicon single crystal substrate and the temperature of the susceptor. The epitaxial wafer manufacturing apparatus is characterized in that the output of the heater element corresponding to the inclined portion is controlled such that the difference between them is 10 ° C. or less . An epitaxial wafer manufacturing method for growing an epitaxial layer on a main surface of a silicon single crystal substrate disposed substantially horizontally on a susceptor,
Heating the silicon single crystal substrate to a predetermined temperature in a non-oxidizing atmosphere by a heater disposed on and / or below the silicon single crystal substrate;
Cooling the heated silicon single crystal substrate to a predetermined epitaxial growth temperature;
Growing an epitaxial layer on the main surface of the silicon single crystal substrate at a predetermined temperature;
Cooling an epitaxial wafer having an epitaxial layer grown on the main surface of the silicon single crystal substrate,
In any of the above steps, the heater is controlled so that the difference between the temperature of the silicon single crystal substrate and the temperature of the susceptor is 10 ° C. or less.
In a plan view when viewed from the silicon single crystal substrate, they are arranged behind the heater radially from the center of the silicon single crystal substrate and rotationally symmetrical with respect to a central axis that stands perpendicular to the center of the silicon single crystal substrate. The reflector is inclined such that heat rays emitted backward from the heater are reflected toward the center of the silicon single crystal substrate at a higher rate than the outer periphery of the silicon single crystal substrate. 60% or more, and the heater includes an inclined portion corresponding heater element corresponding to the inclined portion, and the output ratio of the output of the inclined portion corresponding heater element is set to 60% or less. A method of manufacturing an epitaxial wafer , wherein the output of the heater element corresponding to the inclined portion is controlled by increasing or decreasing the output.

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