JP5378779B2 - Epitaxial wafer manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an epitaxial wafer in which dislocation at a contact part between the epitaxial wafer and a susceptor can be suppressed, or the like. <P>SOLUTION: The method of manufacturing the epitaxial wafer 12 in which an epitaxial layer is grown over a main surface of a silicon wafer substrate placed substantially horizontally on the susceptor includes: a growing step of the epitaxial layer; and a cooling step of cooling the epitaxial wafer 12 having the epitaxial layer. The cooling step includes: a wafer measurement step of measuring a temperature of an outer periphery of the epitaxial wafer; a susceptor measurement step of measuring a temperature of the susceptor 14; and a control step of controlling a heater 16 capable of heating at least the susceptor or the epitaxial wafer such that difference between the temperature of the outer periphery and the temperature of the susceptor is within a predetermined range. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for manufacturing an epitaxial wafer used for a semiconductor integrated circuit element or the like, and more particularly to a method for manufacturing an epitaxial wafer for controlling the temperature of the wafer during epitaxial growth.

  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.

  In the production of an epitaxial wafer, generally, a single crystal silicon wafer serving as a substrate is placed on a susceptor, the silicon wafer serving as a substrate and peripheral components are cleaned, and the surface of the substrate is placed in a silicon source such as silane or trichlorosilane. An epitaxial layer of silicon is grown on the surface by exposure at about 800 ° C. or higher. After growing an epitaxial layer with a predetermined thickness, the supply of the source gas is stopped, the temperature of the silicon wafer loaded with the epitaxial layer is lowered, and the silicon wafer is taken out from the chamber, and this epitaxial wafer is supplied to the next step. Like that. In this series of manufacturing processes, great care is taken not to cause crystal defects such as contamination and dislocations.

  Since the growth of the epitaxial layer is greatly affected by temperature, temperature control is important. Further, when the temperature gradient between the main surface and the back surface of the silicon wafer becomes steep, there is a possibility that the silicon wafer is warped. Even if warpage does not occur, crystal defects called slip dislocations may occur in the wafer. For this reason, when an epitaxial layer is grown on the main surface of the silicon wafer, a source gas is gradually added to prevent a rapid temperature drop, and the output of high-frequency induction applied to the susceptor is controlled, and the susceptor to the silicon wafer is controlled. The movement of heat is limited (for example, Patent Document 1).

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 2002-16004 A JP 2002-164300 A

  However, the temperature control in Patent Document 1 is an effective means for simultaneously controlling the flow rate of the carrier gas and / or the raw material gas and the output such as high-frequency induction, but the flow rate does not change or other heaters (for example, , A halogen lamp) cannot be applied as it is, and the semiconductor wafer is heated by heating from the susceptor, so that the temperature adjustment is not easy to control. On the other hand, in Patent Document 2, by generating a temperature difference between the central portion of the semiconductor wafer and the contact portion (the outer peripheral portion thereof) with the support jig within a predetermined temperature range, The purpose is to suppress the occurrence of dislocations due to the temperature difference between the outer periphery and the outer peripheral portion, and the occurrence of dislocations that may be caused by other factors cannot be effectively suppressed.

  In view of this, the inventor has eagerly studied the outer peripheral portion, particularly in the vicinity of the contact portion with the susceptor, in an epitaxial wafer manufacturing method in which an epitaxial layer is grown on the main surface of a silicon wafer serving as a substrate. Thus, the present invention has been completed, which can effectively prevent the occurrence of dislocations. That is, an object of the present invention is to provide an epitaxial wafer manufacturing method, a manufacturing apparatus, and its components capable of suppressing the occurrence of dislocation at the contact portion between the epitaxial wafer and the susceptor.

  Dislocations originating from the outer periphery, particularly the contact with the susceptor, were found in the silicon wafer manufactured by the epitaxial wafer manufacturing method that is mounted on the susceptor and grows an epitaxial layer on the main surface of the silicon wafer that becomes the substrate. . This was thought to be due to the stress in the vicinity of the outer peripheral portion, but more specifically, it was found to be due to a high temperature difference between the contact portion (and the vicinity) of the silicon wafer and the susceptor. This temperature difference occurs at the outer peripheral portion (or the vicinity thereof) of the silicon wafer.

  In general, in the method for manufacturing an epitaxial wafer, the temperature of the main surface of a silicon wafer serving as a substrate is monitored by a radiation thermometer or the like, but it is not easy to monitor in the vicinity of the outer periphery due to the structure of the apparatus. Therefore, it has been understood that the temperature of the epitaxial wafer is based on the temperature of the central portion of the silicon wafer. By the way, since the temperature distribution in the wafer surface affects the epitaxial growth rate and the like, the temperature management in the central portion and the outer peripheral portion is carefully performed during the epitaxial growth. That is, in the epitaxial growth process, sufficient measures are taken by temperature control at the center of the silicon wafer.

  However, even if sufficient temperature control is performed in the epitaxial growth step, defects such as dislocations may occur in the outer peripheral portion of the obtained epitaxial wafer. Therefore, as a result of intensive research, it was found that, in the process of cooling the epitaxial wafer after epitaxial growth, such a defect occurs when the temperature difference at the contact portion between the silicon wafer and the susceptor is large. That is, during the epitaxial growth, there is not much difference between the temperatures of the silicon wafer and the susceptor, so there is not much temperature difference between the contact portions. In the cooling process of the silicon wafer and susceptor, how to cool the silicon wafer and the susceptor. Due to the difference, a large temperature difference occurs between the two, which becomes a large temperature difference in the contact portion (and the vicinity) of each other.

  In particular, since the central portion of the silicon wafer and the susceptor is monitored from time to time, it may be devised that a large temperature difference does not occur even in the cooling process, but at the central portion and the outer peripheral portion of the silicon wafer, There can be relatively large temperature differences in the cooling process. On the other hand, in the susceptor, the temperature difference between the central portion and the outer peripheral portion is relatively small. Therefore, it is impossible to grasp a large temperature difference between the contact portions (and the vicinity) only by monitoring only the central portion of the silicon wafer.

  Therefore, in the cooling process after epitaxial growth, the temperature of the outer peripheral portion of the silicon wafer is monitored, and the temperature of the susceptor monitored simultaneously with this temperature (the temperature difference between the central portion and the peripheral portion is not so much. The temperature of the cooling process is preferably controlled so that the difference between the temperature and the temperature of the peripheral portion is preferably a predetermined value or less. More specifically, since it is difficult to remove heat from a remote location, the output of an external heater such as a halogen lamp for applying heat is appropriately controlled. Here, since the relationship between the temperature at the center of the silicon wafer and the temperature at the outer periphery in this cooling step is considered constant if the heat dissipation and heating environment are the same, the relationship between the two is determined in advance and measured. However, it is also possible to calculate the temperature of the outer peripheral portion by the temperature of the central portion of the silicon wafer by using a prediction method that obtains the temperature of the outer peripheral portion from the temperature of the central portion that is relatively easy. As a result, the temperature of the outer peripheral portion can be monitored only by monitoring the temperature of the center portion of the silicon wafer, which is relatively easy to measure, and the output of the external heater can be appropriately controlled.

More specifically, the following method can be provided.
(1) In an epitaxial wafer manufacturing method for growing an epitaxial layer on a main surface of a silicon wafer substrate placed on a susceptor arranged in a substantially horizontal state, the epitaxial layer growing step and the epitaxial layer are provided. A cooling step of cooling the epitaxial wafer, wherein the cooling step includes a step of measuring the temperature of the outer peripheral portion of the epitaxial wafer, a step of measuring the temperature of the susceptor, and the measured temperature of the outer peripheral portion. And a step of controlling a heater capable of heating at least the susceptor or the epitaxial wafer so that the difference from the temperature of the susceptor falls within a predetermined range. Can do.

  Here, the outer peripheral portion of the epitaxial wafer can mean a peripheral portion from the outer periphery to 10% of the diameter in the diameter of the disk-shaped wafer. More strictly, it may be up to 5%. Any preferable measuring means such as a thermocouple or a radiation thermometer can be used for the temperature measurement.

(2) In an epitaxial wafer manufacturing method in which an epitaxial layer is grown on a main surface of a silicon wafer substrate placed on a susceptor arranged in a substantially horizontal state, the temperature of the outer peripheral portion is changed from the temperature of the central portion of the silicon wafer substrate. A preliminary process for obtaining a prediction method for obtaining a temperature, and a stratification process for actually growing an epitaxial layer on the main surface of the silicon wafer substrate, wherein the stratification process includes the epitaxial layer growth process and the epitaxial process. Cooling the epitaxial wafer comprising a layer, wherein the cooling step includes a step of measuring a temperature of a central portion of the epitaxial wafer, a step of measuring a temperature of the susceptor, and the measured central portion. The temperature of the outer periphery obtained by the prediction method from the temperature of the susceptor and the temperature of the susceptor Such that the difference is within a predetermined range, it is possible to provide a method for producing an epitaxial wafer which comprises a step of controlling a heater capable of heating at least the susceptor or the epitaxial wafer, a.

  Here, the central portion of the silicon wafer substrate can mean a range of a distance of 10% or less of the diameter measured by a straight line from the circular center of the silicon wafer substrate including the epitaxial layer. More strictly, it can be made 5% or less. The prediction method for obtaining the temperature of the outer peripheral portion from the temperature of the central portion of the silicon wafer substrate may mean a method of obtaining the temperature of the outer peripheral portion from the temperature of the central portion by calculation or the like under a predetermined condition. At this time, since the silicon wafer substrate rotates with the center of rotation coincident with the center of the silicon wafer substrate, it can be assumed that the temperature of the outer peripheral portion is uniform. Accordingly, if the temperature distribution from the central portion toward the outer peripheral portion can be assumed to be uniform in the thickness direction of the silicon wafer substrate, the function of the distance L from the center [the temperature of the outer peripheral portion = F (L, central portion] Temperature). However, L is a radius of the silicon wafer substrate from 0. ]. That is, the heat balance of the silicon wafer substrate is related to a complicated heat path such as heat input and output by radiation of the silicon wafer surface and heater element, cooling effect by convection by the carrier gas flowing on the silicon wafer surface, and heat transfer from the susceptor. A relatively simple calculation formula is expected. For example, the temperature may be calculated as a cubic function related to L. At this time, in the preliminary experiment, it is desirable to measure temperatures at a plurality of locations of 4 or more (more preferably 5 or more) and obtain each constant of the cubic function by the least square method.

(3) The method for producing an epitaxial wafer according to (1) or (2), wherein the cooling step is performed at a predetermined cooling rate or more immediately after the growth step.

(4) The method for producing an epitaxial wafer according to any one of (1) to (3), wherein the epitaxial wafer is cooled from 900 ° C. or higher in the cooling step.

  Here, the reason why the temperature is 900 ° C. or higher is considered to be higher than a temperature at which crystal defects such as dislocations can occur in a silicon wafer including an epitaxial wafer. Therefore, when crystal defects such as dislocations can occur at a lower temperature, it is preferable to perform temperature control in cooling from that temperature or higher. In addition, since the mobility becomes higher at higher temperatures and crystal defects such as dislocations are more likely to occur, the same control is effective in cooling from higher temperatures. However, there is no need to study the generation of crystal defects such as dislocations at a temperature at which silicon melts, so that cooling from a temperature below the melting point is significant.

(5) The method for manufacturing an epitaxial wafer according to any one of (1) to (4), wherein the heater is disposed above the epitaxial wafer and / or below the susceptor. Can be provided.

(6) The method for producing an epitaxial wafer according to (5), wherein, in the cooling step, the output of a heater disposed at least above the epitaxial wafer or below the susceptor is substantially cut off. Can be provided.

  According to the present invention, dislocations generated in the cooling process can be effectively prevented, and a good epitaxial wafer with few defects can be manufactured.

  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 10 according to an embodiment of the present invention. The silicon wafer 12 as a substrate disposed substantially horizontally contacts the contact portion 14a of the susceptor 14 serving as a wafer support member at the contact portion 12a on the outer periphery thereof, and is placed on the susceptor 14. This contact portion 14a is at a step provided at the inner peripheral bottom of the concave portion at the center of the susceptor 14, contacts the silicon wafer 12 at a small contact point (or line or area), and minimizes the influence from the susceptor 14. Ingenuity has been made. A narrow space is provided between the back surface of the silicon wafer 12 and the bottom surface of the concave portion at the center of the susceptor 14, and purge gas flows in through the gap between these members and is filled.

  The core portion composed of the silicon wafer 12 and the susceptor 14 of the epitaxial wafer manufacturing apparatus 10 is surrounded by a chamber 151 in which transparent quartz glass is used on the upper surface and the lower surface, and is hermetically isolated from the outside. In this figure, two halogen lamps 16 are drawn above and below the quartz glass on the top and bottom surfaces, respectively, but the halogen lamps 16 on the top surface are centered on a central axis passing through the center of the silicon wafer 12. Are arranged in a rotationally symmetrical manner (for example, 32). Similarly, a plurality of (for example, 32) halogen lamps 16 below the lower surface are arranged rotationally symmetrically about the same central axis. Here, although not shown, a reflector is provided behind each halogen lamp 16 (on the side far from the chamber 151), and the radiant heat of the halogen lamp is evenly distributed (for example, the central portion and the outer periphery of the silicon wafer 12). To receive a similar amount of heat).

  In this figure, radiant heat thermometers 200 and 210 are provided above the upper surface of the chamber 151 and below the lower surface and corresponding to the central portion of the silicon wafer 12, and the center indicated by the arrows 202 and 212. The temperature of the part is measured.

  FIG. 2 is a schematic diagram showing an epitaxial wafer manufacturing apparatus 10 similar to FIG. 1 according to the embodiment of the present invention. The difference from FIG. 1 is that radiant heat thermometers 220 and 230 are provided at positions corresponding to the outer peripheral portion of the silicon wafer 12 above and below the upper surface of the chamber 151, and are indicated by arrows 222 and 232. The temperature of the outer periphery shown is to be measured.

  1 and 2, the main surface of a single crystal silicon wafer as a substrate is exposed to a silicon source such as silane or trichlorosilane at a temperature of about 800 ° C. or higher, and silicon An epitaxial layer was grown. As epitaxial growth conditions at this time, hydrogen was used as a carrier gas and trichlorosilane was used as a source gas.

  FIG. 3 shows an epitaxial layer grown by the manufacturing apparatus of FIG. 2 and then the epitaxial wafer is allowed to cool substantially (the output of the halogen lamp is minimized. The output ratio between the upper surface side and the lower surface side is about 4: 6) is a graph showing the temperature of the central portion of the epitaxial wafer and the temperature of the susceptor 14 at the corresponding position as a function of time. From this figure, it can be seen that the temperature of the epitaxial wafer 12 is slightly lower than the temperature of the susceptor 14. FIG. 4 shows the time change of the temperature of the outer peripheral portion measured by the radiant heat thermometers 220 and 230 of the manufacturing apparatus of FIG. 2 when the temperature measurement of FIG. 3 is performed. From just before the start of cooling, it can be seen that the temperature of the epitaxial wafer 12 is slightly lower than the temperature of the susceptor 14, and that the temperature difference further increases in the cooling step. Thus, in order to evaluate the temperature difference of the outer peripheral part where the temperature of the outer peripheral part is lower at the temperature of the central part and the outer peripheral part of the epitaxial wafer, and the occurrence of dislocation in the cooling process is concerned, It can be seen that it is preferable to directly measure the temperature of the outer peripheral portion or to obtain a relationship (formula) between the two in advance by a preliminary experiment or the like.

  5 shows an epitaxial layer grown by the manufacturing apparatus shown in FIG. 1, and then the epitaxial wafer is allowed to cool under various conditions (the output of the halogen lamp is changed in several stages. The output ratio between the upper surface side and the lower surface side is also several stages. This is a graph showing the relationship between the temperature and strain by directly measuring the temperature of the outer peripheral portion.

  The vertical axis of this graph represents the amount of strain determined by infrared polarization (or infrared polarization). As is apparent from this graph, the temperature difference at the outer periphery is preferably within a range of plus / minus 30 ° C. (minus 30 to plus 30 ° C.). More specifically, a temperature difference of 30 ° C. or less (a range indicated by an arrow in the figure) is preferable because distortion is sufficiently small and occurrence of dislocations can be suppressed low. When the temperature difference is 10 ° C. or less, the temperature difference is further reduced, which is more preferable.

  FIG. 8 is a graph corresponding to FIG. 5, and is a graph showing the relationship between the temperature difference and strain of the epitaxial wafer in the central portion of the epitaxial wafer and the susceptor at the position corresponding thereto. The cooling conditions at this time are the same as in FIG. In the central part, it is preferable that the temperature difference is plus 40 ° C. or less and minus 20 ° C. or more (that is, plus 40 to minus 20 ° C.). Moreover, it is more preferable that the temperature difference in the central portion is plus 30 ° C. or less and minus 10 ° C. or more.

  FIG. 6 shows the temperature of the outer peripheral portion of the epitaxial wafer when the halogen lamp is appropriately controlled based on the experimental results as described above so that the temperature difference is reduced to 5 ° C. or less, and the temperature corresponds to the temperature. It is the graph which represented the temperature of the susceptor 14 of a position as a function of time. Since more heating by the halogen lamp is applied, the cooling rate is slightly slow, but there is almost no temperature difference and a good epitaxial wafer with few dislocations can be obtained.

  FIG. 7 is a graph showing the relationship between the temperature and strain when starting the cooling process when the temperature difference between the epitaxial wafer and the susceptor at the position corresponding to the epitaxial wafer outer peripheral portion is 30 ° C. As is apparent from this graph, there is almost no distortion if the temperature at the start of the cooling step is 900 ° C. or less, but the distortion increases when the temperature exceeds 900 ° C. In particular, the increase is remarkable at 1050 ° C. or higher. This is because the occurrence of dislocations is likely to occur at high temperatures, and the risk of dislocations is extremely low even if there is a slight temperature difference at low temperatures. It can also be seen that the occurrence of dislocation occurs within a predetermined period immediately after the start of the cooling process where the temperature is still high. This period is at least 3 seconds, depending on the starting temperature. Alternatively, in the cooling step, the temperature difference is preferably suppressed to 30 ° C. or lower until the epitaxial wafer reaches 1000 ° C. or lower, more preferably 900 ° C. or lower.

  FIG. 9 is a schematic cross-sectional view of a susceptor 140 with a reduced heat capacity that can be used in the present invention. Similar to the above-described susceptor 14, there is a recess at the center, and a step is provided at the bottom of the inner peripheral surface. A narrow space 143 is provided between the lower surface of the silicon wafer 12 and the bottom surface of the susceptor 140. In this susceptor 140, the outer peripheral portion 142 is removed, and the heat capacity is kept low. Here, the heat capacity can be determined by specific heat (Cp) × density (ρ) × volume (V). More specifically, the heat capacity is calculated using the physical properties of silicon and graphite summarized in Table 1 below. Can do.

  That is, when the volume V (Si) of the wafer made of silicon is about 70% of the volume V (Su) of the susceptor made of graphite, the same heat capacity is obtained, and the same amount of heat is accumulated per unit time. The temperature will rise at the same rate. At this time, since both materials have a high thermal conductivity of 100 W / m · K or more, it is assumed that the temperature difference in the member can be ignored. As described above, it is preferable to appropriately perform temperature management (increase / decrease in heating output, shading, temperature adjustment of atmospheric gas, etc.) in consideration of the difference in heat capacity between the silicon wafer and the susceptor.

  FIG. 10 is a schematic diagram of the epitaxial wafer manufacturing apparatus 100. In the figure, a silicon wafer 12 is disposed substantially horizontally at the center, and a susceptor 14 on which the silicon wafer 12 is placed and supported is supported by a support arm 161 so as to rotate. At least three support arms 161 are provided so as to be cantilevered and supported by a rotational axis 162 at the center of rotation (the figure shows the case of supporting four). A cylindrical up / down support shaft 164 surrounding the rotating shaft 162 is provided with a lift support arm 163 in a cantilever manner. These chamber members are accommodated in a transparent quartz glass lower cover 158 and upper window 150 so as to be visible. These cover 158 and window 150 are hermetically supported by a base frame 156 and a lid frame 152, respectively. Between the base frame 156 and the main body frame 154, an opening 168 for allowing the carrier gas and the source gas to flow into the chamber and an opening 170 for discharging the mixed gas from the chamber are formed. Below, the halogen lamps 16 are arranged radially and constitute a double heater composed of an inner lamp ring and an outer lamp ring that are rotationally symmetric. Between the inner lamp ring and the outer lamp ring, a reflector 19a is provided in a cylindrical shape so as to isolate them. Further, a cylindrical shape is also provided outside the outer lamp ring so as to surround a similar reflector 19b. Further inside the inner lamp ring, a reflector 20 having a cylindrical shape with a tapered portion at the upper part is disposed so as to cover the above-described up-and-down lifting support shaft 164. Thereby, the radiant heat to a shaft part is intercepted. A plate-like reflector 18 is also provided on the lower side (bottom part) of these halogen lamps 16 to effectively use radiant heat.

  Above the upper window 150, the halogen lamps 16 are similarly arranged in a radial pattern while being entirely covered with a cover 190 to form a double lamp ring that is rotationally symmetric. Direct radiant heat from the halogen lamp 16 is applied to the silicon wafer 12 through the upper window 150. A radiant heat thermometer 200 is provided above the cover 190 and directly above the center of the silicon wafer 12, and measures the temperature of the center of the silicon wafer 12 as indicated by an arrow 202. On the other hand, the central portion of the susceptor 14 is provided with a tube 211 provided therein with an opening serving as a passage for light such as radiant heat above the rotary shaft 162. It is measured.

  In the apparatus as shown in FIG. 10, since the arrangement of each member and the surface state thereof are kept substantially constant, the heat radiation characteristics of the silicon wafer 12 and the susceptor 14 are substantially constant. Accordingly, it is considered that a considerable amount of heat is released from the silicon wafer 12 and the susceptor 14 due to radiation in the case of cooling from a relatively high temperature of about 1000 ° C., but the ratio is relatively constant, and the experiment is performed for each apparatus. If the cooling characteristics based on the above are obtained in advance, the cooling can be performed while keeping the temperature difference at the contact portion between the silicon wafer 12 and the susceptor 14 small. The monitor can perform various temperature monitors and heater controls by converting the temperature obtained by measuring the temperature at the center of the silicon wafer 12 using various relational expressions.

It is the schematic of an epitaxial wafer manufacturing apparatus. It is the schematic of the epitaxial wafer manufacturing apparatus which added temperature monitoring also to the outer peripheral part. It is a graph which shows the time change of the temperature of the epitaxial wafer in the center part of an epitaxial wafer, and the susceptor of the position corresponding to it. It is a graph which shows the time change of the temperature of the epitaxial wafer in the outer peripheral part of an epitaxial wafer, and the susceptor of the position corresponding to it. It is a graph which shows the relationship between the temperature difference of an epitaxial wafer in the epitaxial wafer outer peripheral part, and the position corresponding to it, and a distortion. It is a graph which shows the time change of both temperature when heater control is performed so that the temperature difference of the epitaxial wafer in an epitaxial wafer outer peripheral part and the position corresponding to it may be made small. It is a graph which shows the relationship between the temperature when starting a cooling process, and a distortion, when the temperature difference of the epitaxial wafer in an epitaxial wafer outer peripheral part and the susceptor of the position corresponding to it is 30 degreeC. It is a graph which shows the relationship between the temperature difference of an epitaxial wafer in the epitaxial wafer center part, and the position corresponding to it, and a distortion. It is a schematic sectional drawing of the susceptor which reduced heat capacity. It is a more detailed schematic diagram of an epitaxial wafer manufacturing apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,100 Epitaxial wafer manufacturing apparatus 12 Silicon wafer 12a Contact part 14 with a susceptor, 140 Susceptor 14a Contact part with a silicon wafer 16 Halogen lamp 18, 19a, 19b, 20 Reflector 151 Chamber 200, 210, 220, 230 Radiant heat temperature Total

Claims (8)

In an epitaxial wafer manufacturing method of growing an epitaxial layer on a main surface of a silicon wafer substrate placed on a susceptor arranged in a substantially horizontal state,
A stratification step of actually growing an epitaxial layer on the main surface of the silicon wafer substrate,
The stratification process includes
A growth step of the epitaxial layer;
Cooling the epitaxial wafer comprising the epitaxial layer, and
The cooling step includes
Determining the temperature of the outer periphery of the epitaxial wafer;
The susceptor has substantially no temperature difference between the central part and the peripheral part, but the step of measuring the temperature of the susceptor corresponding to the outer peripheral part of the epitaxial wafer ;
And a step of controlling a heater capable of heating at least the susceptor or the epitaxial wafer so that a difference between the obtained temperature of the outer peripheral portion and the temperature of the susceptor falls within a predetermined range. Epitaxial wafer manufacturing method.   The method for producing an epitaxial wafer according to claim 1, wherein the step of obtaining the temperature of the outer peripheral portion is based on a prediction method for predicting the temperature of the outer peripheral portion from the temperature of the central portion of the epitaxial wafer substrate.   The epitaxial wafer manufacturing method according to claim 2, wherein the predicting method is a method of acquiring a temperature of an outer peripheral portion from a temperature of a central portion of the silicon wafer substrate in a preliminary process.   The method for producing an epitaxial wafer according to claim 1, wherein the step of obtaining the temperature of the outer peripheral portion includes a step of measuring the temperature of the outer peripheral portion of the epitaxial wafer.   5. The method for producing an epitaxial wafer according to claim 1, wherein the cooling step is performed immediately after the growth step at a predetermined cooling rate or higher.   The epitaxial wafer manufacturing method according to claim 1, wherein the epitaxial wafer is cooled from 900 ° C. or higher in the cooling step.   The method for producing an epitaxial wafer according to claim 1, wherein the heater is disposed above the epitaxial wafer and / or below the susceptor.   8. The method of manufacturing an epitaxial wafer according to claim 7, wherein, in the cooling step, the output of a heater disposed at least above the epitaxial wafer or below the susceptor is substantially cut off.

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