JP2005286071A - Wafer support - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wafer support for reducing the cooling or temperature raising time, and keeping the average temperature of the whole surface of a wafer W constant immediately after the temperature modification due to temperature rise or drop, and enabling the repetitive high precision heat treatment of the wafer. <P>SOLUTION: This wafer support comprises a plurality of resistor heating elements provided on the one main surface of, or inside the plate-shaped ceramic body, and a mounting surface in the other main surface on which the wafer is mounted, and has a feeder for independently supplying power to the resistor heating elements respectively and a case for enclosing the feeder, and comprises a gas jet for cooling the plate-shaped ceramic body. An opening is formed in the undersurface of the case, and the opening has 10-70% of the area of the undersurface. The thickness of the wafer support is 10-40 mm, and the variation in the thickness is made not larger than 1 mm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

 The present invention relates to a wafer support member mainly used for heating a wafer. For example, a thin film is formed on a wafer such as a semiconductor wafer, a liquid crystal substrate or a circuit substrate, or a resist solution applied on the wafer. The present invention relates to a wafer support member suitable for forming a resist film by dry baking.

  A wafer support member is a device that heats a wafer such as a semiconductor wafer, a liquid crystal device, or a circuit board, and is used to form a semiconductor thin film on the wafer, or to form a resist film by drying and baking the applied resist solution. Has been.

  Conventional semiconductor manufacturing apparatuses include a batch type that heats a plurality of wafers at once, and a single wafer type that heats one wafer at a time. As a result of demands for miniaturization of wafers and improved accuracy of wafer heat treatment temperature, they are widely used.

  In recent years, the wafer size has been increased in order to improve the production efficiency, but the semiconductor elements themselves have also diversified, and manufacturing with a large wafer does not necessarily improve the production efficiency, but rather a single device. It is desired that wafers of various sizes can be heated in accordance with the respective heat treatment conditions.

  In Patent Document 1, a wafer lift pin for supporting a wafer surface and transferring a wafer is used with respect to a wafer support member including a hot plate that has a heating element on the lower surface and heats the wafer on the upper surface and a case that supports the hot plate. Thus, an apparatus capable of dealing with wafers of various sizes is disclosed.

  In this conventional apparatus, as shown in FIG. 4, a ceramic hot plate 54 is fixed to an opening on a case 69. The hot plate is provided with a resistance pattern 55 as a heating element on a lower surface 59, and the upper surface is heated. A mounting surface 53 on which a wafer W to be mounted is mounted. A pin insertion sleeve 62 is erected at the bottom of the case and contacts the lower surface 59 of the hot plate 54, and the insertion hole of the sleeve 62 communicates with the through hole 76 formed in the hot plate 54. Yes. The lift pin is inserted into the insertion hole of the pin insertion sleeve 62 and the through hole 76 of the hot plate 54, and is lowered while holding the wafer at the upper end of the lift pin, and the wafer is placed on the hot plate. The wafer is lifted above the hot plate to facilitate wafer removal.

  In this apparatus, a port 67 for supplying fluid for circulating cooling air inside the case 69 is provided at the bottom of the case, and in the process of cooling the wafer after heat treatment, the port 67 The air is blown onto the hot plate to increase the temperature lowering speed and shorten the wafer cooling time.

  As a wafer support member, for example, Patent Document 2 discloses a wafer support member 250 in which a resistance heating element 212 is formed on the bottom surface of a ceramic substrate 211 as shown in FIG. It is sectional drawing typically represented, (b) is a perspective view which shows typically the baseplate which comprises the case of this wafer support member. In this figure, air that is a refrigerant is configured to circulate to the bottom plate 260.

  In this wafer support member 250, an insulating film 218 is formed on the surface of the ceramic substrate 211, and support pins 259 are installed on the surface of the ceramic substrate 211 having the insulating film 218, and the silicon wafer 219 is attached to the ceramic substrate. It is held at a certain distance from the heating surface 211.

  Further, a resistance heating element 212 is formed on the surface of the insulating film 218 of the ceramic substrate 211, and a power supply terminal 213 is connected to an end of the resistance heating element 212. The power supply terminal 213 is connected to a power source (not shown) via a socket 255 and a conductive wire 262. By applying a voltage via the conductive wire 262 and the like, the resistance heating element 212 is heated, and ceramic The substrate 211 can be heated. Further, although not shown, a thermocouple (temperature measuring element) for temperature control is embedded in the ceramic substrate 211.

  Further, the ceramic substrate 211 on which the insulating film 218 is formed is fitted into a heat insulating reinforcing member 252 installed on the case 270, and the heat insulating reinforcing member 252 is thermally insulated by a pin 251 inserted through the heat insulating reinforcing member 252. On the other hand, the ceramic substrate 211 is fixed to the heat insulating reinforcing member 252 by pins 251 and fixing brackets 253.

  The case 270 is formed with a bottom plate 260 formed integrally with the case 270 and an opening 260 a used for air discharge, and is provided with a refrigerant supply pipe 258. Further, a sleeve 257 that protects a lifter pin for transferring the silicon wafer to the transfer machine is provided in the case 270.

  Further, an inner bottom plate 256 supported by a leaf spring 254 is provided inside the case 270, and an opening 256a is formed in the inner bottom plate. Moreover, as shown in FIG.5 (b), the hollow 260k is formed in the bottom plate 260 vertically and horizontally like the grid pattern. The reason why the large number of depressions 260k are provided in this way is to correct the distortion of the bottom plate by these depressions 260k.

  In addition, in Patent Document 3, as shown in FIG. 6, in the structure of a case having a bottom plate and a bottom plate for supporting a ceramic substrate, a recess 20 is formed in the plate 11 so that the flatness is 0.2 mm or less. Suppressed wafer support members have been proposed.

  Further, in Patent Document 4, as shown in FIG. 7, in order to quickly cool the ceramic substrate 21 installed in the case 10, an opening 20 is provided in the plate-like body 12 around the refrigerant supply pipe 14 of the case 10. A formed wafer holding member has been proposed.

The thickness of the above wafer support member was as large as 50 mm. Further, the case 10 is formed by welding the upper surface of the outer peripheral portion of the disk forming the bottom surface or the cylinder forming the side surface to the outer peripheral surface of the disk, so that there is no R at the corner of the case 10 and an edge is formed. It had been.
JP 2001-52985 A JP 2002-25758 A JP 2002-141399 A JP 2003-100818 A

  By the way, a wafer support member used for a single wafer type wafer support member which has been attracting attention in recent years has a plate thickness of the plate-like ceramic body 2 as thin as 1 to 7 mm in order to shorten the processing time tact on the wafer W. The cycle time for heating and cooling is adjusted to be short. However, when the thickness of the plate-like ceramic body 2 is reduced to 1 to 7 mm, the entire surface of the wafer W cannot be heated uniformly so as to have a temperature variation of ± 0.5 ° C.

  That is, when the plate thickness of the plate-like ceramic body 2 is reduced to 1 to 7 mm, the plate-like ceramic body 2 is warped and the distance from the wafer W changes, so that the surface temperature of the wafer W varies. It was.

  Further, in recent years, since further densification has progressed and the sensitivity of the resist film to the light source has become sensitive, the conventional wafer support member has a thin ceramic substrate. There was a problem that the temperature was transferred to the wafer and could not be baked uniformly.

  In addition, with recent miniaturization, the sensitivity of the resist film to the light source has become more sensitive, so with the conventional hot plate, the temperature uniformity of the wafer mounting temperature immediately after the temperature change and the temperature cannot be kept constant, The problem was that the yield was significantly reduced because a uniform product could not be maintained.

  In addition, the temperature rise curve differs between the ceramic substrate and the case due to temperature changes, so the time until the temperature stabilizes is different, and as the wafer processing is repeated, the case temperature gradually rises and falls, and the resist film is baked. There was a problem that variations occurred.

  Thus, as a result of intensive studies on the above problems, the inventors have provided a plurality of resistance heating elements on one main surface or inside of the plate-like ceramic body, and a mounting surface on which the wafer is placed on the other main surface. A gas injection port for cooling the plate-shaped ceramic body, the wafer support member having a power supply section that supplies power independently to each of the resistance heating elements, and a case surrounding the power supply section 10 to 70% of the area is formed on the bottom surface of the case, the thickness of the wafer support member is 10 to 40 mm, and the variation in thickness is 1 mm or less.

  The flatness of the annular region around the bottom surface is 100 μm or less.

  Further, the space between the bottom surface and the side surface of the case is a chamfered shape or an R shape.

  Further, the size of the chamfer is 0.1 to 2 mm, or the R shape of the R shape is 0.2 to 50 mm.

  Further, the thickness of the case forming the bottom surface is 2 to 7 mm, and an opening of 20 to 60% of the area is provided on the bottom surface of the case.

  Moreover, the shape of the said opening part consists of a circular arc and a straight line, It is characterized by the above-mentioned.

  In addition, the ratio of the area of the opening formed of a circular arc and a straight line to the area of the opening formed of a circle is 30 to 70%.

  In addition, an opening made of the arc and a straight line is provided at the center of the bottom surface.

  In addition, the opening ratio of the central portion of the bottom surface of the case is larger than the opening ratio of the outer peripheral portion.

  Wafer support that heats the wafer repeatedly and accurately from immediately after the temperature change because the time required for raising and lowering the temperature of the wafer placed on the mounting surface of the wafer support member is shortened and the time until the wafer support member is stabilized is shortened. A member can be provided.

  Embodiments for carrying out the present invention will be described below.

  First, FIG. 1 is a sectional view showing an example of a wafer holding member 1 which is an example of the present invention. FIG. 2 shows a cross-sectional view in which the wafer holding member 1 of the present invention is attached to the wafer heat treatment chambers 31, 32, 33. The chamber is composed of main parts including the chamber upper portion 33, the chamber lower portion 32, and the reinforcing member 31.

In recent years, with the reduction in throughput, the chamber upper portion 33 is also provided with a heater (
Devices incorporating (not shown) have come to be adopted. In the method in which the heater is incorporated in the chamber upper portion 33, the distance between the chamber 33 and the plate-like ceramic body 2 is important in reducing the in-plane temperature difference of the wafer W. Therefore, FIG. ing.

  As shown in FIG. 1, the wafer support member 1 of the present invention includes a plate-like ceramic body 2 in which a hot plate 4 has an upper main surface as a wafer mounting surface 3, and the inside or the bottom of the plate-like ceramic body 2. The heating element 5 is arranged on the main surface, and the wafer support member 1 is inserted through the through-hole 26 penetrating the hot plate 4 to lift and lower the wafer W, and the wafer lift pins are inserted and guided. A guide member 12 is provided. The wafer support member 1 includes a cylindrical case 19 that supports the peripheral edge of the hot plate 4. The interior space of the case includes a lift pin 25 and a guide member 12 at the lower portion of the hot plate. Yes.

  The plate-like ceramic body 2 is made of a ceramic sintered body, and is preferably made of an oxide, carbide, nitride sintered body. Usually, it has a disk shape. One main surface of the plate-like ceramic body 2 is used for placing the wafer W, the heating resistor 5 is disposed on the other main surface or inside, and a through hole 26 for inserting the lift pin 25 is provided. Further, the peripheral edge of the plate-like ceramic body 2 is fixed to the peripheral edge of the upper opening of the cylindrical case 19.

  Then, the wafer W is supported with the lift pins 25 lifted upward, the lift pins are lowered, the wafer W is placed on the mounting surface 3, current is supplied to the heating element 5 from the outside, and the wafer W is heated. It can be heated at a constant temperature.

  When the thickness of the plate-shaped ceramic body 2 is 2 to 7 mm, the strength of the hot plate 4 can be secured and the heat capacity of the hot plate 4 can be reduced. Furthermore, the time until the temperature during heating and cooling becomes steady can be shortened. The plate-like ceramic body 2 is preferably made of a material having a Young's modulus of 200 GPa or more, and the deformation amount is small with respect to thermal stress and the plate thickness can be reduced.

  The plate-like ceramic body 2 is preferably made of a material having a thermal conductivity of 60 W / (m · K) or more, and conducts the heat generated by the resistance heating element 5 even with a thin plate thickness. Temperature variation can be reduced. From these points, a sintered body of silicon carbide or aluminum nitride is preferable.

  A wafer support member 1 of the present invention includes a plurality of resistance heating elements 5 on one main surface or inside of a plate-like ceramic body 2, and a wafer support member 1 including a mounting surface 3 on which the wafer is placed on the other main surface. In addition, a power feeding unit 6 that supplies power to each of the resistance heating elements 5 independently, a case surrounding the power feeding unit, and an opening 23 for cooling the plate-like ceramic body 2 are provided. Is provided.

  Further, the opening 23 is on the bottom plate 21 of the case 19, and by forming an opening of 10 to 70% of the area of the bottom plate 21, the lower surface of the plate-like ceramic body 2 is appropriately cooled, and the temperature within the wafer surface is increased. This is preferable because the variation is small. The ratio of the opening to the area of the bottom plate 21 is defined as an aperture ratio. By setting the aperture ratio to 10% or more, the heat capacity of the bottom plate is reduced, so that the overshoot of the temperature of the wafer after temperature change is preferably reduced. Further, by setting the aperture ratio to 70% or less, since the rigidity of the bottom plate is maintained, there is no deformation of the planar shape of the hot plate, and the distance between the hot plate and the wafer is kept uniform, so the surface of the wafer W This is preferable because variations in internal temperature can be suppressed.

  The aperture ratio is a value obtained by multiplying the total area of the openings on the lower surface of the bottom plate 21 by 100 times the value obtained by dividing the area of the bottom plate 21.

  Further, it is preferable that the thickness L of the wafer support member 1 is 40 mm or less because the apparatus is downsized and the efficiency of circulation of the cooling medium is improved. When the thickness is 40 mm or less, the wafer support member 1 is reduced in size, so that the heat capacity of the apparatus is reduced, and the time until each member such as the bottom plate after the temperature change is shortened is preferable.

  Further, it is preferable that the variation in the thickness L of the wafer support member 1 is 1 mm or less because the temperature variation in the surface of the wafer W is reduced.

  As described above, the time required for raising and lowering the temperature of the wafer support member is shortened, the time until the heater is stabilized is shortened, and a wafer support member capable of processing wafers with high repeatability immediately after the temperature change can be provided.

  Details will be described below. When the hot plate 4 is heated from 120 ° C. to 150 ° C., the plate-like ceramic body 2 in which the heating element 5 is formed directly below the plate-like ceramic plate 2 due to the temperature rise of the hot plate 4, The temperature rise curves of the bottom plate 21 of the case 19 where the temperature rises due to direct contact from the thermocouple 27 or air by heat transfer are different, and there is a difference in the time until each stabilizes. Therefore, immediately after the temperature rises, the wafer support member 1 has a large heat sink from the thermocouple 27, the bottom plate 21 of the case 19 and the air, so that the wafer support member 1 has a low temperature in order to maintain the set temperature. In order to sense, it is usually P.I. I. Due to the D control, excessive power is supplied and overshoot occurs. Since the overshoot is reduced and the wafer temperature is reduced, the variation in wafer temperature can be reduced by balancing the heat capacity with the hot plate, the casing, and the chamber. Further, the thermocouple 27 must be formed in the concave groove portion 10 of the plate-like ceramic body 2 in order to detect the accurate temperature of the ceramic support member 1. In this case, paying attention to the aperture ratio, shape, flatness, and flatness of the bottom plate 21 of the case 19, a method for making the wafer surface temperature uniform was studied.

  First, when the opening ratio of the bottom plate 21 of the support container is less than 10%, even if the plate-like ceramic body 2 reaches the set temperature, the heat capacity of the metal portion of the bottom plate 21 is large, so the temperature change of the wafer W is slow. turn into. That is, when the wafer W is mounted immediately after the temperature rise, the heat capacity of the bottom plate 21 is large, so that the temperature rise of the bottom plate becomes slow, and the temperature detection by the thermocouple 27 of the ceramic body 2 becomes low, and the output Will be controlled to raise. Therefore, the temperature of the wafer gradually increases.

  On the other hand, if the aperture ratio is greater than 80%, the opening portion of the bottom plate 21 is large, so the heat capacity of the bottom plate 21 decreases and the temperature of the bottom plate 21 rises quickly, so the thermocouple 27 detects that the temperature is high. And control to lower the output. Therefore, the temperature of the wafer W tends to gradually decrease. If the aperture ratio is 80% or more, the rigidity of the bottom plate 21 is lost, the flatness and flatness of the outer periphery cannot be set to predetermined values, and the temperature accuracy of the wafer W becomes 0.5 ° C. or more. Because it ends up.

  The thickness L of the wafer support member 1 is the thickness of the space through which the plate-like ceramic body 2 and the cooling medium (refrigerant) circulate and the case 19, from the wafer mounting surface 3 to the bottom of the bottom plate 21 of the case 19. Distance. The thickness L of the wafer support member 1 is preferably 40 mm or less. This is because the volume in the case 19 is small and can be reduced in weight. Further, if it is larger than 40 mm, the size in the support container is increased, the heat capacity is increased, and if the space is increased, it is thermally insulated by air and heat conduction from the plate-like ceramic body 2 to the support container is hindered. This is because the temperature rise curve of the support container becomes gentle and the time until stabilization becomes too long.

  Further, if the thickness L of the wafer support member is smaller than 10 mm, the distance between the hot plate 4 and the bottom plate 21 is too short, so that the temperature variation on the wafer surface increases due to the radiation of the opening 23 of the bottom plate 19. The in-plane temperature difference of the wafer W may be 0.5 ° C. or more.

  When the thickness L of the wafer support member 1 is 10 to 40 mm, the temperature rise and fall characteristics are excellent, and the size and weight can be reduced. Moreover, it is preferable that the variation of the thickness L is 1 mm or less. This is because by reducing the variation in the thickness L, the distance between the chamber upper portion 33 and the wafer W can be kept uniform, so that the influence of heat radiation from the chamber upper portion 33 to the wafer W can be suppressed. In recent years, for the purpose of improving throughput, a method in which a heater is incorporated in the upper chamber portion 33 has been used. That is, the temperature distribution of the heater in the chamber upper portion 33 may affect the temperature of the wafer W.

  Further, it is preferable that the flatness of the outer peripheral portion of the bottom plate 21 of the case 19 of the present invention is 100 μm or less because the temperature of the wafer is improved. The outer peripheral portion indicates a range outside 70 to 99% of the diameter of the bottom plate 21. The flatness is a value obtained by measuring eight points on the same circle and subtracting the minimum value from the maximum value. By setting the flatness of the bottom plate 21 to 100 μm or less, it is preferable that the amount of deformation along the end surface of the reinforcing member 31 is reduced when the bottom plate 21 is fixed with the reinforcing member 31 and the bolt 16 of the chamber lower portion 32 processed with high accuracy. More preferably, the flatness of the outer peripheral portion of the bottom plate 21 is 50 μm or less.

  Since the reinforcing member 31 of the chamber lower portion 32 serves as a reference surface for fixing the case, the flatness is 50 μm or less, and the smaller one is 20 μm or less.

  Moreover, it is preferable that the corner | angular part (outside of the connection part of the side plate 22 and the baseplate 21) of the case 19 is formed in a chamfered shape or R shape. For example, if the burr at the corner is not removed, the flatness of the plate-like ceramic body 2 may be increased, and the in-plane temperature difference of the wafer W may be increased. In addition, since the contact area between the bottom plate 21 and the chamber lower portion 31 is reduced, the bottom plate is thermally insulated, so that the temperature tends not to decrease, and the temperature of the wafer W after the temperature change is not stable. This is because the burrs at the connecting portion between the side plate 22 and the bottom plate 21 are removed so that a gap is not generated in the attachment to the reinforcing member 31.

  The chamfer size is preferably 0.1 to 2 mm. If the size of the chamfer is less than 0.1 mm, burrs at the corners may not be sufficiently removed. Further, if the size of the chamfer exceeds 2 mm, the strength of the case 19 may be lowered due to the balance with the plate thickness of the case 19. These cases 19 are formed by machining such as grinding the upper surface of the outer peripheral portion of the bottom plate 21 forming the bottom surface or the corner portion of the bottomed case formed by welding the cylinder forming the side plate 22 to the outer peripheral surface of the bottom plate 21. Thus, a chamfered shape can be obtained.

  Moreover, it is preferable that the corner | angular part (connection part of the side plate 22 and the baseplate 21) of case 19 is R shape. The size of the R shape is preferably 0.2 to 50 mm. This is because it is difficult to form the R shape when the size of the R shape is less than 0.2 mm, and the chamfered shape can be substituted. When the R shape exceeds 50 mm, the balance with the thickness of the wafer support member 1 is considered. This is because the cylindrical portion is reduced and the rigidity of the case 19 may be reduced. More desirably, in order to increase the rigidity of the case 19, the size of the R shape is desirably 3 or more. More preferably, it is 5-10R. Note that R is represented by a diameter.

  Moreover, in order to form said shape, it is preferable that the side plate 22 and the baseplate 21 of the case 19 are integral. The integrated case 19 can be formed by forming a side plate from a circular plate by drawing. The case prepared by the above drawing process has high rigidity despite its relatively small plate thickness, and has a high rigidity and a high degree of rigidity with little deformation even when the wafer holding member 1 is attached to the apparatus or repeated heating and cooling. The wafer holding member 1 can be provided.

  Further, in the case of an integral one, the connecting portion is simplified, so that the heat capacity can be reduced and the rigidity can be increased.

  In addition, the repeatability of temperature stability immediately after the temperature change can be expressed by the wafer average temperature change amount after the temperature rise temperature change and the wafer average temperature change amount after the temperature fall temperature change shown below.

  From the state in which the temperature of the hot plate 4 (the temperature indicated by the thermocouple 27 incorporated in the plate-like ceramic body 2) is stabilized at 120 ° C. for 1 hour, the set temperature is heated to 150 ° C. The temperature of the thermocouple 27 incorporated in the ceramic body 2 is made to reach 150 ° C. After 150 seconds from the start of the temperature change, a silicon wafer with a temperature measuring element cooled to room temperature was placed on the placement surface, the average temperature of the wafer temperature was measured, and this was set as the initial wafer temperature T1. Moreover, the average value T2 of the temperature of the 17-point wafer after 1 hour was measured. And the difference which subtracted T2 from T1 was made into the wafer average temperature change amount after temperature rising temperature change.

  Further, the temperature of the hot plate 4 (temperature indicated by the thermocouple 27 incorporated in the plate-like ceramic body 2) is stabilized at 180 ° C. for 1 hour, and then the set temperature is lowered to 150 ° C. Air is blown from the nozzle 24 to the heating element 5, and the temperature of the thermocouple 27 incorporated in the plate-like ceramic body 2 with the slowest temperature drop reaches 150 ° C. After 150 seconds from the start of the temperature change, a silicon wafer with a 17-point temperature measuring element cooled to room temperature was placed on the mounting surface, and the average temperature T3 of the wafer was measured to obtain the initial wafer temperature. And the average value T4 of the wafer temperature of 17 points after 1 hour was measured. And the difference which subtracted T3 from T4 was made into wafer average temperature change amount after temperature-fall temperature change. The wafer average temperature change amount after the temperature rise temperature change and the wafer average temperature change amount after the temperature drop temperature change are preferably smaller, and if it is small, the temperature reproducibility is excellent.

  On the other hand, it is preferable that the thickness of the bottom plate 21 is 2 to 7 mm. Since the rigidity of the bottom plate 21 having a thickness of the bottom plate 21 smaller than 2 mm is weakened and the deformation amount is increased, the flatness of the plate-like ceramic body 2 is deteriorated. Further, if the thickness of the bottom plate 21 is larger than 7 mm, the rigidity of the bottom plate 21 is increased, but the heat capacity of the bottom plate 21 is increased, so that the temperature rise of the bottom plate 21 is delayed and the responsiveness is deteriorated. When the temperature is raised, a temperature difference between the plate-like ceramic body 2 and the bottom plate 21 occurs. Therefore, immediately after the temperature rise, the wafer support member 1 has a large amount of heat drawn from the thermocouple 27, the bottom plate 21 of the case 19 and the air. I. With D control, excess power is supplied as much as it is considered to be low due to heat extraction, overshooting, and the wafer average temperature change amount of 0.05 ° C. after the temperature rise temperature change cannot be satisfied.

  In addition to the above, it is preferable that the aperture ratio of the bottom plate 21 is 20 to 70%. When the opening ratio of the bottom plate 21 is smaller than 20%, and the thickness of the bottom plate 21 exceeds 7 mm and the heat capacity of the bottom plate 21 is large, the temperature of the bottom plate 21 with respect to the temperature change of the ceramic support member 1 is increased. Since it takes time to rise and stabilize, the difference in heat capacity with the ceramic plate-like body 2 increases, the bottom plate 21 draws heat, and the ceramic heater 1 controls the heating. Therefore, the surface temperature of the wafer W placed on the plate-like ceramic body 2 may be increased.

  Conversely, when the aperture ratio of the bottom plate 21 exceeds 70% and the plate thickness is less than 2 mm and the heat capacity is small, there is no overshoot, but the rigidity of the bottom plate 21 is lost, and the surface temperature difference of the initial wafer W is increased. It is because there exists a possibility of exceeding 0.5 degreeC.

  Moreover, it does not specifically limit as a shape of the opening part 23, For example, the shape which consists of a circular arc and a straight line, trapezoid shape, a rectangular shape, etc. are mentioned. In addition, it is preferable that the shape of several opening combines a different shape rather than the same shape. Moreover, it is preferable that the shape of the opening part 21 consists of a circular arc, a straight line, and a circle.

  Moreover, it is preferable that the area ratio of the opening at the center (region having a diameter of 50%) is larger than the area ratio of the opening at the outer periphery (50 to 99% of the diameter). This is because the central part of the plate-like ceramic body 2 tends to collect heat and is difficult to cool, and thus providing an opening made of a circular arc and a straight line at the central part improves the cooling efficiency. Further, the shape of the opening in the outer peripheral portion of the bottom plate 21 is preferably a circular shape. This is because the flatness of the outer peripheral portion of the bottom plate is effectively suppressed. On the other hand, the arc and the straight line tend to cause the flatness and warpage of the bottom plate because the rigidity of the bottom plate is weakened.

  Moreover, as shown in FIG. 3, it is preferable that the ratio of the area of the opening part 101 in which the shape of the opening part 23 is a circular arc and a straight line and the area of the opening part 102 made of a circle is 30 to 60%. Since the area ratio of the opening is 30% to 60% by setting the area ratio of the opening made of an arc and a straight line to the area of the opening made of a circle, the cooling efficiency is good and the rigidity of the bottom plate is maintained. is there. Further, it is preferable to provide an opening 101 formed of an arc and a straight line at the center of the bottom plate 21. This is because the circulation of the refrigerant to the central portion is improved by providing the opening 101 having a circular arc and a straight line at the center. Moreover, it is because the curvature of a baseplate can be made small by providing the circular opening part 102 in an outer peripheral part.

  Furthermore, it is because it can improve further by making the total area of an opening part into 20 to 60% in the case where the opening ratio of a center part is larger than the opening ratio of an outer peripheral part.

  Moreover, it is preferable that the Young's modulus of the material of the baseplate 21 is 150 GPa or more. This is because the bottom plate 21 can increase the rigidity and reduce the thickness of the bottom plate 21. If the Young's modulus of the material of the bottom plate 21 is less than 150 GPa, the rigidity of the bottom plate is small, and the substrate may be bent.

  The material of the bottom plate 21 is preferably a SUS plate. Further, it is optimal that the bottom plate has a uniform structure by heat treatment. The material of the bottom plate 21 may be ceramic.

  Next, other configurations will be described.

  The heating element 5 provided on the hot plate 4 is patterned from a strip of resistance material and is embedded in the plate-like ceramic body 2 or attached to the lower main surface as shown in FIG. Has been. The resistor strips can be configured by being arranged in a concentric or spiral pattern, and are divided into several heating elements 5 in the surface area of the plate-like ceramic body 2, and each heating element 5 is continuous. It is possible to provide a distribution of the amount of heat generated so that the temperature is uniform in the entire plate-shaped ceramic body 2 by controlling the electric power of each heating element 5 by using a resistor circuit formed of a strip.

  The hot plate 4 is fixed on the case 19, and the case 19 has a bottomed cylindrical shape and has a bottom through hole 26 through which the wafer lift pin 25 is inserted at the bottom, and the lower end side of the guide member 12. The upper opening fixes the peripheral edge of the hot plate 4.

  The lift pins 25 are erected so as to be movable up and down by a driving device disposed under the case 19, and preferably three or more wafer lift pins 25 are used. The lift pin 25 passes through the through hole 26 of the case 19, passes through the guide hole of the lift pin holding member, passes through the through hole of the plate-like ceramic body 2, and is arranged so that the tip protrudes from the upper surface of the substrate. Is done. The lift pins 25 can receive the wafer W conveyed from the outside at the upper end of the wafer lift pins 25, lower the wafer lift pins 25, and place them on the wafer placement surface 3 of the hot plate 4. The lift pins 25 are simultaneously lifted to remove the wafer after the heat treatment from the mounting surface.

  The lift pin 25 is formed of a thin metal wire, and preferably has a diameter of 2 to 6 mm. If the lift pins 25 are thinner than 2 mm in diameter, it is not preferable because sufficient rigidity cannot be secured, the wafer is easily bent by the load of the wafer, and the stability of the wafer mounting and removal is lacking. If the diameter is larger than 6 mm, the diameter of the through hole 26 of the plate-like ceramic body 2 is increased, and a cool spot is generated on the wafer W thereon, which is not preferable.

  The through hole 26 of the plate-like ceramic body 2 is inserted through the lift pin 25. If the inner diameter of the through hole 26 is 2 to 8 mm, temperature variation around the through hole can be suppressed and the wafer can be heated uniformly in a short time. This is preferable. If the inner diameter of the through-hole 26 exceeds 8 mm, the through-hole 26 that is a non-heated region of the hot plate 4 becomes too wide, and even if the heat density of the surrounding resistance heating element 5 is adjusted, it is not possible to ensure thermal uniformity. It is not preferable.

  The guide member 12 is a cylindrical body that is fixed to the bottom 21 and is disposed on the lower main surface side of the hot plate 4 and has a guide hole formed therein, and the tip of the lift pin 25 is a plate-like ceramic in the guide hole. It has a function of directing it so that it can be inserted into the through hole 26 of the body 2.

  Such a guide member 12 is generally selected from metals, ceramics, and heat resistant polymers. The guide member has a columnar shape or a cylindrical shape having a rectangular or circular cross section and other deformations in common. The guide hole of the guide member 12 has a diameter through which the lift pin 26 can be inserted, and the inner diameter of the guide hole is preferably 2 to 8 mm corresponding to the diameter of the lift pin 25.

  The upper end surface of the guide member 12 is thinned to have an annular shape with a wall thickness of 0.1 to 3.0 mm, and the amount of heat transfer from the substrate to the upper end surface can be reduced. The thickness of the upper end surface refers to the thickness or width between the outer periphery of the end surface and the inner periphery of the guide hole. When the thickness of the upper end surface of the guide member exceeds 3.0 mm, the amount of heat transfer between the plate-shaped ceramic body 2 and the guide member increases, and when the thickness of the plate-shaped ceramic body 2 is small, There is a possibility that the temperature of the part corresponding to the through hole 26 of the substrate is lower than that of the other part. If the wall thickness is smaller than 0.1 mm, the upper end surface of the guide member may be thermally deformed during the heat treatment, and sufficient strength cannot be obtained.

  The annular thickness of the upper end surface of the guide member is more preferably 0.1 to 0.5 mm. Such a thick guide member reduces the amount of heat transferred from the portion directly above the guide member of the hot plate to the guide member, thereby suppressing a decrease in temperature around the contact surface of the hot plate and cooling the wafer surface. The generation of spots can be prevented.

  The case 19 is made of metal (for example, stainless steel SUS304), and includes a bottom portion 21 and a cylindrical side surface 22 and has a cylindrical container shape. The case has a distance of 10 to 40 mm from the upper surface of the bottom portion 21 to the lower main surface 7 of the plate-like ceramic body 2, and a void is formed inside the case. This distance facilitates the soaking of the wafer mounting surface due to the mutual radiant heat between the hot plate 4 and the inner surface of the case 19 and has a heat insulating effect from the outside. Therefore, the time until the mounting surface 3 is soaked is increased. Since it becomes short, it is preferable.

  The bottom portion 21 of the case 19 is provided with a through hole 10 for a lift pin, the lower surface of the guide member 12 is fixed with screws, and the guide hole 14 communicates with the through hole 10. In this example, the case 19 is also provided with a gas injection port 24 and a gas discharge port 23 at the bottom 21 to supply a cooling gas (usually air) to the internal space and after heat treatment. The plate-like ceramic body 2 can be forcibly cooled. Further, the bottom portion 21 penetrates the conduction terminal 11 and the thermocouple 27 in an electrically insulating manner.

  The hot plate is elastically fixed to the opening of the case 19 through the bolt 16 from above, with the heat insulating portion 17 interposed, and the nut 20 being screwed.

  The case 19 is provided with a bottom plate 21 integrally on the inner bottom of a cylindrical outer frame 22 and has a substantially bottomed cylindrical shape. The outer frame 22 and the bottom plate 21 may not be provided integrally, and the bottom plate 21 may be connected and fixed to the outer frame 22 by bolts, welding, or the like. The bottom plate 21 is provided with a plurality of openings 23.

  A silicon carbide sintered body having a thermal conductivity of 80 W / (m · K) is ground to produce a plurality of disk-shaped hot plates having a plate thickness of 3 mm and an outer diameter of 330 mm. In order to deposit an insulating layer on the main surface, a glass paste prepared by kneading glass cellulose with ethyl cellulose as a binder and terpineol as an organic solvent was laid by screen printing and heated to 150 ° C. for organic After drying the solvent, degreasing treatment was performed at 550 ° C. for 30 minutes, and baking was performed at a temperature of 700 to 900 ° C. to form an insulating layer made of glass having a thickness of 200 μm.

  Next, in order to deposit a resistance heating element on the insulating layer, a paste in which 20 wt% Au powder, 10 wt% Pt powder and 70 wt% glass are mixed as a conductive material is printed in a predetermined pattern shape. The organic solvent was dried by heating to 150 ° C., degreased at 450 ° C. for 30 minutes, and baked at a temperature of 500 to 700 ° C. to form a resistance heating element having a thickness of 50 μm. The resistance heating element has a five-pattern configuration in which the central portion and the outer peripheral portion are divided into four in the circumferential direction. And the said hot plate was attached to the case, the temperature measuring element, the electric power feeding terminal, etc. were attached, and various wafer support members were produced.

  The opening of the bottom plate of the case was manufactured with a laser having an aperture ratio of 5 to 80%. Moreover, the thickness of the side plate of the case of the wafer supporting member member was 2-8 mm by grinding the upper and lower surfaces of the bottom plate. Moreover, the thickness L of the supporting member was 8 to 50 mm by changing the height of the side surface of the case. In addition, three types of variations of the thickness L of the wafer support member were produced: about 2 mm, 1 mm, and 0.5 mm. The 2 mm product was obtained by punching the bottom plate with a laser, and the 1 mm product was pressed by sandwiching the upper and lower surfaces with a metal plate to improve the flatness. In addition, for 0.2 and 0.5 mm products, the flatness was further improved by grinding the bottom plate. A hot plate was produced using the above three kinds of bottom plates.

  The evaluation method is shown below.

(1) Temperature rise time The temperature rise time is to heat the set temperature to 150 ° C from the state where the temperature of the hot plate (the temperature indicated by the thermocouple 27 incorporated in the plate-like ceramic body) is stabilized at 120 ° C for 1 hour. The time required for the temperature of the thermocouple 27 incorporated in the plate-shaped ceramic body having the slowest temperature to reach 150 ° C. was defined as the temperature increase time.

(2) Temperature drop time The temperature drop time is the same as when the temperature of the hot plate (the temperature indicated by the thermocouple 27 incorporated in the plate-like ceramic body) is stabilized at 180 ° C. for 1 hour, and then the set temperature is lowered to 150 ° C. The time until the temperature of the thermocouple built in the plate-shaped ceramic body with the slowest temperature drop reached 150 ° C. was blown from the cooling nozzle 24 to the heat generating element.

(3) Initial wafer temperature range After placing a silicon wafer with a temperature sensor on the mounting surface and heating the hot plate and stabilizing it for 1 hour, it is divided so that the average temperature of the entire wafer is 150 ° C. Adjust the temperature of the resistance heating element. The temperature of the wafer surface was measured using the silicon wafer with the temperature measuring element, and the difference obtained by subtracting the minimum value from the maximum value was defined as the initial wafer temperature range.

(4) Change in wafer average temperature after temperature rise temperature change The temperature of the hot plate (temperature indicated by the thermocouple incorporated in the plate-shaped ceramic body) is stabilized at 120 ° C for 1 hour, and then the set temperature is 150 ° C. And the temperature of the thermocouple 27 incorporated in the plate-shaped ceramic body having the slowest temperature rise is made 150 ° C. After 150 seconds from the start of the temperature change, a silicon wafer with a temperature measuring element cooled to room temperature was placed on the placement surface, the average temperature of the wafer temperature was measured, and this was set as the initial wafer temperature T1. Moreover, the average value T2 of the temperature of the 17-point wafer after 1 hour was measured. And the difference which subtracted T2 from T1 was made into the wafer average temperature variation | change_quantity after temperature rising temperature change.

(5) Wafer average temperature change after temperature change (℃)
From a state where the temperature of the hot plate (temperature indicated by the thermocouple 27 incorporated in the plate-shaped ceramic body) is stabilized at 180 ° C. for 1 hour, the set temperature is lowered to 150 ° C., and at the same time, air is supplied from the cooling nozzle. It blows on a heat generating body, and the temperature of the thermocouple incorporated in the plate-shaped ceramic body with the slowest temperature fall reaches 150 degreeC. After 150 seconds from the start of the temperature change, a silicon wafer with a 17-point temperature measuring element cooled to room temperature was placed on the mounting surface, and the average temperature T3 of the wafer was measured to obtain the initial wafer temperature. And the average value T4 of the wafer temperature of 17 points after 1 hour was measured. And the difference which subtracted T3 from T4 was made into wafer average temperature change amount after temperature-fall temperature change.

Each result is as shown in Table 1.

  As is clear from the results shown in Table 1, the sample No. No. 1 has a small aperture ratio and a large heat capacity, so that the temperature drop time was as large as 140 seconds and a slow result was obtained. Sample No. with an aperture ratio of 80% was used. No. 4 showed good results with a temperature drop time of 115 seconds, but the rigidity of the bottom plate decreased and the flatness of the soaking plate deteriorated, so the initial wafer temperature range was 0.6 ° C, which was a bad result. It was.

  In addition, the sample No. 1 in which the thickness of the wafer support member is smaller than 10 mm. 5, the thickness is as small as 8 mm, and the distance between the hot plate and the bottom plate becomes too small, so that the soaking of the hot plate deteriorates due to the influence of the radiant heat of the members incorporated in the bottom plate, and the initial wafer temperature at the wafer surface The temperature range became as large as 0.7 ° C.

  In addition, the sample No. 4 in which the thickness of the wafer support member is larger than 40 mm. In No. 8, the temperature drop time was 130 seconds, and a bad result was obtained.

  In addition, sample No. with a wafer support member thickness variation of more than 1 mm. For No. 11, the wafer average temperature difference after changing the temperature rise was 0.11 ° C., and a bad result was obtained. Since the thickness variation of the wafer support member is as large as 2 mm, the distance between the wafer W placed on the placement surface and the upper portion of the chamber is not constant but close, so that the heater incorporated in the upper portion of the chamber (not shown) It seems that the temperature variation became large due to the influence of temperature unevenness.

  On the other hand, Sample No. with an aperture ratio of 10 to 70%, a wafer support member thickness of 10 to 40 mm, and a wafer support member thickness L variation of 1 mm or less. In 2, 3, 6, 7, 9, and 10, the temperature drop time is as small as 113 seconds, 111 seconds, 113 seconds, 114 seconds, 110 seconds, and 109 seconds, and the amount of change in the average wafer temperature after changing the temperature rise is 0.050. Good results were obtained which were as small as below ° C.

  Further, the sample No. 1 in which the thickness variation of the wafer support member is 0.5 mm or less. In Nos. 9 and 10, the wafer average temperature change after changing the temperature increase / decrease temperature was as small as 0.04 ° C. or less, and more preferable results were obtained.

  Evaluation was performed by changing the flatness of the outer peripheral portion of the bottom plate 21 of the case 19. The predetermined flatness was produced by the following method. The opening part of the baseplate 21 was processed with the laser, and the thing whose outer periphery flatness was 200 micrometers was produced. Further, a substrate having a thickness of 100 μm was prepared by sandwiching the bottom plate between two upper and lower metal plates. Furthermore, the upper and lower surfaces of the bottom plate were ground to produce a 50 μm bottom plate. Using the three bottom plates, a wafer support member 1 was produced in the same manner as in Example 1. In order to confirm the influence of the flatness of the bottom plate, the same three types of plate-like ceramic bodies 2 were used.

  In addition, the measuring method of the flatness of an outer peripheral part measured 80 places on the concentric circle of 80% of the diameter of the plate-shaped ceramic body 2 at the same space | interval, and measured the difference with the maximum value-minimum value as flatness. The evaluation method was the same as in Example 1.

The results are shown in Table 2.

  As shown in Table 2, the sample No. 1 in which the flatness of the outer peripheral portion of the bottom plate of the case 19 is larger than 100 μm. In No. 18, the initial wafer temperature range and the wafer average temperature change amount after changing the temperature increase / decrease temperature were 0.050 ° C. However, Sample No. with a flatness of the outer peripheral portion of 100 μm or less. In Nos. 16 and 17, both the wafer average temperature change after the temperature rise temperature change and the wafer average temperature change after the temperature drop temperature change were 0.045 ° C. or less, and good results were obtained.

  Various studies were made on the R shape of the corner of the bottom plate of the case. As the bottom plate 21 of the case 19, a product with a chamfered shape, an R shape, and a product without a chamfered outer peripheral corner portion were produced. Further, the chamfered size of the outer peripheral portion was 0.5 mm and 1 mm. Further, the size of R at the corner of the case produced by deep drawing the case was about 2 mm. Assembled and evaluated by the same method as in Example 1.

The results are shown in Table 3.

  As shown in Table 3, the sample No. which is not chamfered. In No. 21, the initial wafer temperature range was 0.2 ° C., and the change in wafer temperature after changing the temperature rise temperature was 0.05 ° C.

  However, the sample No. 1 in which the corner of the bottom plate 21 of the case 19 is chamfered by 0.5 mm or rounded. In Nos. 22 and 23, the initial wafer temperature range was 0.15 ° C., and the change in wafer temperature after changing the temperature rise temperature was as small as 0.04 ° C.

  Sample No. In No. 24, since the size of the R shape was as large as 20 mm and the contact with the bottom plate was stable, the change in the average temperature of the wafer after changing the temperature rise temperature was further preferably as small as 0.035 ° C.

  In the same manner as in Example 1, a wafer support member was fabricated using a bottom plate in which the thickness of the bottom plate of the case made of SUS was changed from 1 mm to 8 mm and the aperture ratio was changed from 10% to 70%.

  The flatness of the outer peripheral portion of the bottom plate of the case was 100 μm or less, and the flatness of the entire bottom plate was 300 μm or less. The evaluation method was the same as in Example 1.

The results are shown in Table 4.

  As shown in Table 4, the sample No. 1 in which the thickness of the bottom plate of the case is 1 mm and the aperture ratio is 60%. In No. 31, the initial wafer temperature range was 0.2 ° C., and the wafer average temperature change amount after the temperature change was 0.040 ° C.

  Further, Sample No. 2 having a bottom plate thickness of 2 mm, an aperture ratio of 10%, and 70%. Nos. 32 and 35 had a wafer average temperature change amount of 0.040 ° C. after changing the temperature rise / fall temperature.

  Further, Sample No. having a bottom plate thickness of 8 mm and an aperture ratio of 60% was used. In No. 40, the wafer average temperature change amount after the temperature change was 0.040 ° C.

  On the other hand, the sample No. 2 in which the thickness of the bottom plate of the case is 2 to 7 mm and the opening ratio of the bottom plate of the case is 20 to 60%. In 33, 34, 37, and 38, the temperature rise time was 50 seconds, the temperature drop time was 100 seconds, and the wafer average temperature change after changing the temperature rise / fall temperature was as small as 0.030 ° C., and good results were obtained.

  In the same manner as in Example 1, a case was produced in which a bottom plate of a case having an opening made of an arc and a straight line and an opening made of a circle was drilled by laser processing. The number of circular openings was increased on the outer periphery, and the decrease in the strength of the bottom plate of the case was suppressed. Moreover, the test was performed by changing the ratio of the shape of the opening. Four types of case bottom plates were produced in which the ratio (S1 / S2 × 100) of the opening S1 made of an arc and a straight line to the opening S2 made of a circle (S1 / S2 × 100) was 20%, 30%, 70%, and 80%. The opening ratio of the entire bottom plate was fixed at 40%. The evaluation method was the same as in Example 1.

The results are shown in Table 5.

  As shown in Table 5, the sample No. 5 has a ratio of the opening made of an arc and a straight line to the opening made of a circle smaller than 30%. In No. 41, the amount of change in wafer temperature after changing the temperature rise / fall was 0.030 ° C.

  Sample No. with a ratio of 80%. 44, the change in wafer temperature after the change in temperature was as high as 0.030 ° C.

  However, Sample No. with a ratio of the opening made of an arc and a straight line to the opening made of a circle of 30 to 70%. In Nos. 42 and 43, the change in wafer temperature after changing the temperature rise / fall temperature was as good as 0.020 ° C. for both temperature rise and fall.

  A wafer support member was produced by changing the ratio of the aperture ratio between the center portion of the bottom plate 21 from the center of the bottom plate 21 to 50% of the diameter of the bottom plate 21 and the outer peripheral portion outside the center portion, and evaluated in the same manner as in Example 4.

The opening ratio of the central portion (diameter direction 0 to 50%) is the opening area of the central portion / (π × (the radius of the bottom plate / 2) ² ) × 100%, and the outer peripheral portion (radial direction 50% to 100%). The aperture ratio of the outer peripheral portion was calculated by the following equation: Opening area of outer peripheral portion / (π × (radius of bottom plate) ² −π × (radius of bottom plate / 2) ² ).

The results are shown in Table 6.

  As shown in Table 6, the sample No. Sample No. 51 with a small opening ratio in the center part. Compared with No. 52, the wafer average temperature change amount after changing the temperature rise / fall temperature was further reduced, and a good result of 0.015 ° C. was obtained. Since the central part tends to collect heat, it is considered that the larger the aperture ratio, the better.

  In the same manner as in Example 1, four types of case bottom plates having an aperture ratio of 10%, 20%, 60%, and 70% were prepared as Sample Nos. As shown in FIG. 51, a sample having a larger opening ratio in the central portion than in the outer peripheral portion was produced. The evaluation method was the same as in Example 1.

The results are shown in Table 7.

  As shown in Table 7, Sample No. with an opening ratio of the bottom plate smaller than 20% or larger than 60%. Nos. 61 and 64 had a wafer average temperature change amount of 0.015 ° C. after changing the temperature increase / decrease temperature.

  However, Sample No. with an aperture ratio of 20 to 60%. In 62 and 63, the change amount of the wafer temperature after changing the temperature rise / fall temperature was as small as 0.010 ° C. and good.

It is sectional drawing of the wafer support member of this invention. It is sectional drawing which shows the state which attached the wafer support member of this invention to the apparatus. It is a figure which shows the bottom plate of the case in the wafer support member of this invention. It is sectional drawing of the conventional wafer support member. It is sectional drawing of the conventional wafer support member, and a figure which shows the baseplate of a case. It is a figure which shows the baseplate of the case in the conventional wafer support member. It is sectional drawing of the conventional wafer support member, and a figure which shows the baseplate of a case.

Explanation of symbols

W: Semiconductor wafer L: Thickness of wafer support member
1: Wafer support member 2: Plate-like ceramic body 3: Wafer mounting surface 4: Hot plate 5: Resistance heating element 6: Power supply unit 8: Support pin 10: Temperature measuring element, thermocouple 11 Power supply terminal 16: Bolt 18: Elastic body 19: Case 20: Nut 23: Opening 25: Wafer lift pin 26: Through hole 31: Reinforcing member 32: Lower chamber 33: Upper chamber 100: Hot plate 101: Opening made of arc and straight line 102: Opening made of circle Part

Claims (9)

A wafer supporting member comprising a plurality of resistance heating elements on one main surface or inside of a plate-like ceramic body, and a mounting surface on which the wafer is placed on the other main surface, each independent of the resistance heating elements. A power supply section for supplying electric power and a case surrounding the power supply section, provided with a gas injection port for cooling the plate-like ceramic body, and an opening of 10 to 70% of its area on the bottom surface of the case The wafer support member is characterized in that the thickness of the wafer support member is 10 to 40 mm and the variation in thickness is 1 mm or less. The wafer support member according to claim 1, wherein the flatness of the annular region around the bottom surface is 100 μm or less. The wafer support member according to claim 1, wherein a space between the bottom surface and a side surface of the case is a chamfered shape or an R shape. The space between the bottom surface and the side surface of the case is a chamfered shape having a size of 0.1 to 2 mm, or an R shape having a size of 0.2 to 50 mm. Wafer support member. 5. The wafer support according to claim 1, wherein a thickness of the case forming the bottom surface is 2 to 7 mm, and an opening of 20 to 60% of the area is provided on the bottom surface of the case. Element. 6. The wafer support member according to claim 1, wherein the shape of the opening is an arc and a straight line. The wafer according to any one of claims 1 to 6, wherein a ratio of the area of the opening formed of an arc and a straight line to the area of the opening formed of a circle is 30 to 70%. Support member. The wafer support member according to claim 1, wherein an opening made of the arc and a straight line is provided at a central portion of the bottom surface. The wafer support member according to claim 1, wherein an opening ratio of a central portion of the bottom surface of the case is larger than an opening ratio of an outer peripheral portion.

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