JP2012023183A - Wafer holder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer holder which can favorably transport a wafer by using a noncontact transport device with holding the wafer without deteriorating film quality.SOLUTION: The wafer holder 1A holds a wafer W and a concave pocket portion 10A is formed on a principal surface 5. The pocket portion 10A is formed of a bottom portion 20 on which the wafer W is placed and a sidewall portion 30 continuing to the principal surface 5 and the bottom portion 20. A depth D from the principal surface 5 to the bottom portion 20 is deeper than 50% of a wafer thickness H. The sidewall portion 30 has a sidewall upper portion 32 continuing to the principal surface 5 and a sidewall lower portion 34 continuing to the sidewall upper portion 32 and the bottom portion 20. With respect to a cross section passing the center O of the bottom portion 20 and perpendicular to the principal surface 5, a sidewall contact point K that is a contact point of the sidewall upper portion 32 and the sidewall lower portion 34 exists within a range from a point higher than a height from the bottom portion 20 to 50% of the wafer thickness H to a point lower than a wafer surface 200 opposite to the bottom portion 20. With respect to the section, the sidewall upper portion 32 inclines such that a principal surface contact P separates from the central axis C further than the sidewall contact point K.

Description

  The present invention relates to a wafer holder that holds a wafer.

  In recent years, a wafer on which a film such as GaN is formed has been used as a semiconductor device. In order to form a film on a wafer, a manufacturing apparatus capable of performing heat treatment at a high temperature in a gas atmosphere is known (see, for example, Patent Document 1). In such a manufacturing apparatus, a wafer holder having a pocket portion is used to hold a wafer.

  When the wafer is transferred from the wafer holder, contact with the wafer may damage the formed film and reduce the quality of the wafer. For this reason, in recent years, non-contact transfer apparatuses that can transfer without contacting a wafer are widely known (see, for example, Patent Document 2).

  The non-contact transfer device ejects air to the wafer and discharges air from the gap between the non-contact transfer device and the wafer. As a result, the cushion chamber, which is the space inside the non-contact transfer device, becomes negative pressure, and the wafer is sucked. When the distance between the non-contact transfer device and the wafer becomes short, air is not ejected and the pressure in the cushion chamber increases. As a result, a force acts in the direction in which the wafer is separated. In this way, the non-contact transfer device can transfer without contacting the wafer.

JP-A-2004-55595 Japanese Patent Laid-Open No. 2001-322080

  During the transfer, the air discharged from the gap between the non-contact transfer device and the wafer collides with the side wall of the pocket portion, and the airflow is disturbed. This turbulence in airflow prevents air from being discharged, and the pressure in the cushion chamber becomes unstable. For this reason, the wafer is not attracted well and a transfer error occurs.

  If the side wall is lowered, the exhausted air does not collide with the side wall, but the wafer may protrude from the pocket portion beyond the side wall during the film forming process. As a result, the wafer was not heated evenly and a low quality film was formed. Furthermore, in recent years, in order to form a film evenly on the wafer, the wafer holder may be rotated during the film formation process. If the side wall is low, this rotation may cause the wafer to jump out of the pocket.

  Accordingly, the present invention has been made in view of such a situation, and provides a wafer holder that can be suitably transferred using a non-contact transfer device while holding the wafer without deteriorating the quality of the film. With the goal.

  In order to solve the above-described problems, the present invention has the following features. A feature of the present invention is a wafer holder (wafer holder 1A, wafer holder 1B) that has a main surface (main surface 5) and holds a wafer (wafer W). The main surface has a concave pocket portion (pocket portion). 10A, pocket portion 10B), and the pocket portion is constituted by a bottom portion (bottom portion 20) on which the wafer is placed, and a side wall portion (side wall portion 30) connected to the main surface and the bottom portion, The depth from the main surface to the bottom portion (depth D) is deeper than 50% of the wafer thickness (wafer thickness H), which is the thickness of the wafer, and the side wall portion is the upper portion of the side wall (side wall side) continuous with the main surface. An upper portion 32) and a sidewall lower portion (side wall lower portion 34) connected to the sidewall upper portion and the bottom portion, and passes through the center (center O) of the bottom portion and is perpendicular to the main surface. At the point of contact with the bottom The side wall contact (side wall contact K) is in a range higher than 50% of the wafer thickness from the bottom and lower than the wafer surface (wafer surface 200) opposite to the bottom, and the main surface and the upper side of the side wall Is a main surface contact (main surface contact P), and an axis that passes through the center of the bottom and is perpendicular to the main surface is a central axis (center axis C), the main surface contact is the side wall contact in the cross section. The gist is that the upper portion of the side wall is inclined so as to be further away from the central axis.

  According to the feature of the present invention, the depth from the main surface to the bottom is deeper than 50% of the wafer thickness, which is the thickness of the wafer, and in the cross section passing through the center of the bottom and perpendicular to the main surface, The side wall contact, which is a contact with the bottom, is in a range higher than 50% of the wafer thickness from the bottom and lower than the wafer surface opposite to the bottom, so that the main surface contact is farther from the central axis than the side wall contact in the cross section. The upper part of the side wall is inclined. For this reason, since the wafer is held so that the position of the center of gravity of the wafer is lower than the height of the main surface, the wafer can be prevented from protruding or jumping out from the pocket portion. Since the upper part of the side wall is inclined, the air hitting the side wall flows along the inclination, so that the airflow is not disturbed. For this reason, a wafer can be conveyed suitably.

  Another feature of the present invention is that, in the cross section, an angle (angle θ) about the side wall contact formed by a straight line (straight line m) passing through the side wall contact and perpendicular to the main surface and the upper side of the side wall is The gist is that the angle is 10 degrees or more and 45 degrees or less.

  Another feature of the present invention is that when the center of the bottom portion and the center of the bottom surface of the wafer coincide with each other, a distance (distance L) from the lower portion of the side wall to the side surface of the wafer is 0.25 mm or more and 0.5 mm or less. It is a summary.

  Another feature of the present invention is summarized in that a protrusion (protrusion 50) that protrudes from the side wall and can contact the side surface of the wafer is formed in a plan view perpendicular to the main surface.

  Another feature of the present invention is summarized in that the tip of the protrusion (projection tip 56) is formed in an arc shape in the plan view.

  Another feature of the present invention is summarized in that the curvature radius (curvature radius R1) of the tip portion is 0.5 mm or more in the plan view.

  Another feature of the present invention is that, in the plan view, an end portion (projection end portion 58) of the projection portion connecting the side wall portion and the projection portion is formed in an arc shape, and the end portion of the projection portion is The gist is that the radius of curvature (the radius of curvature R2) is 10 mm or more.

  Another feature of the present invention is that three or more protrusions are formed, and the interval between the protrusions is constant.

  Another feature of the present invention is summarized in that three or more protrusions are formed, and the protrusions are arranged point-symmetrically with respect to the center of the bottom in the plan view.

  Another feature of the present invention is that the wafer holder is made of silicon carbide.

  ADVANTAGE OF THE INVENTION According to this invention, the wafer holder which can be conveyed suitably using a non-contact conveying apparatus can be provided, hold | maintaining a wafer, without reducing the quality of a film | membrane.

FIG. 1 is a perspective view of a wafer holder 1A according to the first embodiment. FIG. 2 is a cross-sectional view of the pocket portion 10A according to the first embodiment. FIG. 3 is a perspective view of a wafer holder 1B according to the second embodiment. FIG. 4 is an enlarged plan view of the wafer holder 1B according to the second embodiment. FIG. 5 is a perspective view of the protrusion 50. FIG. 6 is a plan view of the protrusion 50. FIG. 7 is a cross-sectional view of the pocket portion 10B according to the second embodiment.

  An example of a wafer holder according to the present invention will be described with reference to the drawings. Specifically, (1) 1st Embodiment (2) 2nd Embodiment, (3) Operational Effects, (4) Other Embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. It should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. It goes without saying that the drawings include parts having different dimensional relationships and ratios.

(1) First Embodiment (1.1) Schematic Configuration of Wafer Holder 1A A schematic configuration of a wafer holder 1A according to the first embodiment will be described with reference to FIG. FIG. 1 is a perspective view of a wafer holder 1A according to the first embodiment.

  As shown in FIG. 1, the wafer holder 1A has a disk shape. Wafer holder 1 </ b> A has a main surface 5. In the wafer holder 1 </ b> A, a concave pocket portion 10 </ b> A that holds the wafer W is formed on the main surface 5. A plurality of pocket portions 10A are formed in the wafer holder 1A.

  Wafer holder 1 </ b> A is used to form a film on wafer W. For this reason, wafer holder 1A is preferably made of silicon carbide. Since silicon carbide has a high thermal conductivity, the wafer W can be heated uniformly. As a result, the film is not uneven, and a film of good quality is formed on the wafer W.

(1.2) Schematic Configuration of Pocket Part 10A A pocket part 10A according to the first embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view of the pocket portion 10A according to the first embodiment. That is, FIG. 2 is a cross-sectional view taken along the line AA in FIG. Specifically, it is a cross-sectional view of the pocket portion 10A in a cross section passing through the center O of the bottom portion 20 of the pocket portion 10A and perpendicular to the main surface 5. However, in FIG. 2, not only the pocket portion 10 </ b> A but also a cross section of the wafer W and the non-contact transfer apparatus 100 is shown.

  As shown in FIG. 2, the pocket portion 10 </ b> A includes a bottom portion 20 on which the wafer W is placed, and a side wall portion 30 that continues to the main surface 5 and the bottom portion 20. The side wall portion 30 includes a side wall upper portion 32 that is continuous with the main surface 5 and a side wall lower portion 34 that is continuous with the side wall upper portion 32 and the bottom portion 20.

  The depth D of the pocket portion 10A, that is, the depth from the main surface 5 to the bottom portion 20 is deeper than 50% of the wafer thickness H, which is the thickness of the wafer W. In order to further suppress the wafer W from popping out by the rotation of the wafer holder 1A, the depth D is more preferably deeper than 50% of the wafer thickness H.

  A contact between the sidewall upper part 32 and the sidewall lower part 34 is referred to as a sidewall contact K. A contact between the main surface 5 and the upper side wall 32 is referred to as a main surface contact P. An axis passing through the center O of the bottom portion 20 and perpendicular to the main surface 5 is defined as a central axis C. As shown in FIG. 2, the side wall upper portion 32 is inclined such that the main surface contact P is further away from the central axis C than the side wall contact K. That is, the side wall upper part 32 is formed in a taper shape. Therefore, in a plan view perpendicular to the main surface 5, the boundary line constituted by the contact point between the main surface 5 and the side wall upper part 32 is larger than the boundary line constituted by the contact point between the side wall upper part 32 and the side wall lower part 34. The straight line m passing through the side wall contact K and perpendicular to the main surface 5 and the side wall upper portion 32 form an angle θ with the side wall contact K as the center. This angle θ is preferably not less than 10 degrees and not more than 45 degrees.

  The side wall lower part 34 is formed in parallel with the straight line m. The side wall lower part 34 is formed perpendicular to the bottom part 20.

  The side wall contact K is in a range higher than 50% of the wafer thickness H that is the thickness of the wafer W from the bottom 20 and lower than the wafer surface 200 opposite to the bottom 20. Therefore, if the height from the bottom 20 to the side wall contact K is a height h, H / 2 <h ≦ H. Since the side wall part 30 has the side wall upper part 32, the depth D becomes higher than the height h.

  The pocket portion 10A can be formed by grinding the main surface 5 of the wafer holder 1A. When wafer holder 1A consists of silicon carbide, pocket part 10A can be formed by grinding using a diamond grindstone.

  The pocket portion 10A is preferably formed so that the wafer W to be placed and the side wall portion 30 have an appropriate distance relationship. Specifically, when the center O of the bottom portion 20 and the center of the bottom surface of the wafer W are matched, the distance L from the side wall lower portion 34 to the side surface of the wafer W is preferably 0.25 mm or more and 0.5 mm or less. .

(1.3) Transfer of Wafer W Transfer of the wafer W placed on the wafer holder 1A according to the first embodiment will be described with reference to FIG.

  The non-contact conveyance device 100 takes in air from the inlet 112, passes through the cushion chamber 110 formed inside the non-contact conveyance device 100, and jets out the air taken in from the jet port 117. As shown in FIG. 2, when the non-contact transfer apparatus 100 is brought close to the wafer W, the ejected air is discharged from the gap between the non-contact transfer apparatus 100 and the wafer W. As a result, the pressure in the cushion chamber 110 decreases, and the wafer W exerts a force in a direction approaching the non-contact transfer apparatus 100. When the distance between the non-contact transfer apparatus 100 and the wafer W becomes shorter, the gap between the non-contact transfer apparatus 100 and the wafer W becomes narrower, so that air discharge is suppressed. As a result, the pressure in the cushion chamber 110 rises, and the wafer W exerts a force in a direction away from the non-contact transfer apparatus 100. By adjusting the distance between the non-contact transfer apparatus 100 and the wafer W so that these forces are balanced, the non-contact transfer apparatus 100 suspends and holds the wafer W. By moving the non-contact transfer device 100 on which the wafer W is suspended and held, the wafer W can be transferred without contacting.

  As shown in FIG. 2, the discharged air generates an air flow S. Since the pocket part 10A has the inclined side wall upper part 32, the airflow S that has hit the side wall upper part 32 travels along the inclination. Accordingly, the airflow S flows from the pocket portion 10 </ b> A toward the main surface 5. Therefore, even if the airflow S collides with the side wall upper portion 32, it is possible to suppress the airflow S that has collided from flowing back into the gap between the non-contact transfer apparatus 100 and the wafer W. For this reason, the airflow is not disturbed, and the pressure in the cushion chamber 110 can be maintained at a pressure at which the wafer W can be suspended and held. Accordingly, the wafer W can be suitably transferred using the non-contact transfer apparatus 100.

(2) Second Embodiment A wafer holder 1B according to a second embodiment of the present invention will be described with reference to FIGS. In the following description, the same parts as the wafer holder 1A are omitted as appropriate.

(2.1) Schematic Configuration of Wafer Holder 1B and Pocket Part 10B The schematic configuration of the wafer holder 1B and pocket part 10B according to the second embodiment will be described with reference to FIGS. FIG. 3 is a perspective view of a wafer holder 1B according to the second embodiment. FIG. 4 is an enlarged plan view of the wafer holder 1B according to the second embodiment. Specifically, FIG. 4 is a plan view of the pocket portion 10B viewed from a direction perpendicular to the main surface 5 of the wafer holder 1B in FIG. FIG. 5 is a perspective view of the protrusion 50. FIG. 6 is a plan view of the protrusion 50. FIG. 7 is a cross-sectional view of the pocket portion 10B according to the second embodiment. That is, FIG. 7 is a BB cross-sectional view of FIG. Specifically, it is a cross-sectional view of the pocket portion 10B in a cross section passing through the center O of the bottom portion 20 of the pocket portion 10B and perpendicular to the main surface 5. However, as in FIG. 2, cross sections of the wafer W and the non-contact transfer apparatus 100 are also shown.

  As shown in FIG. 3, a plurality of concave pocket portions 10 </ b> B for holding the wafer W are formed in the main surface 5 in the wafer holder 1 </ b> B. As shown in FIGS. 3 and 4, the pocket portion 10 </ b> B has a protrusion 50. The protrusion 50 protrudes from the side wall 30 in a plan view (hereinafter, abbreviated as a plan view as appropriate) viewed from a direction perpendicular to the main surface 5. The protrusion 50 is formed so as to be able to contact the side surface of the wafer W (see FIG. 7). As shown in FIGS. 5 and 6, the protrusion 50 includes a protrusion tip 56 and a protrusion end 58.

  As shown in FIGS. 5 and 6, the protrusion tip 56 is the tip of the protrusion 50. In plan view, the protrusion tip 56 is formed in an arc shape. Specifically, the protrusion tip 56 is formed so as to be directed in the c direction which is the central axis C direction. That is, it is formed such that the arc of the protrusion tip 56 is directed in the c direction. The radius of curvature R1 of the protrusion tip 56 is preferably 0.5 mm or more.

  As shown in FIGS. 5 and 6, the protruding end portion 58 connects the side wall portion 30 and the protruding portion 50. The protruding end 58 is formed in an arc shape. Specifically, the protruding end 58 is formed so that the arc of the protruding end 58 is outside the pocket portion 10B. It is preferable that the curvature radius R2 of the protrusion end portion 58 is 10 mm or more.

  As shown in FIGS. 5 to 7, the protrusion 50 includes a protrusion upper portion 52 corresponding to the sidewall upper portion 32 and a protrusion lower portion 54 corresponding to the sidewall lower portion 34. That is, the protrusion upper part 52 is smoothly connected to the sidewall upper part 32, and the protrusion lower part 54 is smoothly connected to the sidewall lower part 34. Further, as shown in FIG. 7, the protrusion upper part 52 is continuous with the main surface 5, and the protrusion lower part 54 is continuous with the protrusion upper part 52 and the bottom part 20. A contact point between the protrusion upper portion 52 and the protrusion lower portion 54 is defined as a protrusion contact K ′. A contact point between the main surface 5 and the protrusion upper portion 52 is defined as a main surface contact point P ′. The protrusion upper portion 52 is inclined such that the main surface contact P ′ is further away from the central axis C than the protrusion contact K ′. Therefore, the straight line m ′ passing through the protrusion contact K ′ and perpendicular to the main surface 5 and the protrusion upper portion 52 form an angle φ with the protrusion contact K ′ as the center. Similarly to the angle θ, the angle φ is preferably 10 degrees or more and 45 degrees or less.

  A space between the wafer W and the side wall 30 can be secured by the protrusion 50. Specifically, as shown in FIG. 7, the wafer W can be prevented from approaching the side wall portion 30 when the side surface of the wafer W and the protrusion lower portion 54 come into contact with each other. Thereby, the space between the wafer W and the side wall part 30 is securable. The air flow S proceeds along the inclination of the protrusion upper part 52 and flows to the main surface 5, or proceeds from the protrusion upper part 52 to the side wall upper part 32 and flows from the side wall upper part 32 toward the main surface 5. For this reason, it is possible to suppress the airflow S from flowing back into the gap between the non-contact transfer apparatus 100 and the wafer W. Therefore, similarly to the wafer holder 1A, also in the wafer holder 1B, the distance L from the side wall lower portion 34 to the side surface of the wafer W can be maintained at 0.25 mm or more.

  As shown in FIGS. 3 and 4, a plurality of protrusions 50 are formed. Specifically, five protrusions 50 are formed in the wafer holder 1B. It is preferable to determine the number of protrusions 50 to be formed according to the diameter of the wafer W to be processed. If the diameter of the wafer W is small and the number of protrusions 50 formed is small, the wafer W may enter between the protrusions 50. In such a case, since the effect of forming the protrusions 50 cannot be obtained, it is preferable to form a plurality of protrusions 50 according to the diameter of the wafer W. Specifically, when the diameter of the wafer W is 200 mm, it is preferable that three or more protrusions 50 are formed. When the diameter of the wafer W is 200 mm, it is preferable that three or more protrusions 50 are formed. When the diameter of the wafer W is 100 mm, it is preferable that five or more protrusions 50 are formed. When the diameter of the wafer W is 50 mm, it is preferable that six or more protrusions 50 are formed.

  When a plurality of protrusions 50 are formed, it is preferable that the interval between the protrusions 50 is constant in plan view so that the wafer W does not enter between the protrusions 50. Here, the term “constant” does not have to be strictly constant, but may be substantially equal so that the effect of the present invention can be obtained. For the same reason, as shown in FIG. 4, the protrusions 50 are arranged point-symmetrically with respect to the center O of the bottom 20 in plan view. Here, the point symmetry does not have to be strictly point symmetry, and may be substantially point symmetrical to the extent that the effect of the present invention can be obtained.

(3) Action / Effect According to the wafer holder of the present invention, the depth D is deeper than 50% of the wafer thickness H, and the side wall contact K is higher than 50% of the wafer thickness H from the bottom 20. In the range lower than the wafer surface 200 on the opposite side, the sidewall upper part 32 is inclined such that the principal surface contact P is further away from the central axis C than the sidewall contact K. Since the side wall upper part 32 is inclined and the side wall contact K is in a range lower than the wafer surface 200 on the side opposite to the bottom part 20, it is discharged from the gap between the non-contact transfer apparatus 100 and the wafer W during transfer. The airflow S generated by the air travels along the inclination of the upper side wall 32. Accordingly, the airflow S flows from the pocket portion 10 </ b> A toward the main surface 5. Therefore, even if the airflow S collides with the side wall upper portion 32, it is possible to suppress the airflow S that has collided from flowing back into the gap between the non-contact transfer apparatus 100 and the wafer W. For this reason, the airflow is not disturbed, and the pressure in the cushion chamber 110 can be maintained at a pressure at which the wafer W can be suspended and held. As a result, the wafer W can be suitably transferred using the non-contact transfer apparatus 100.

  The depth D is deeper than 50% of the wafer thickness H, and the side wall contact K is in a range higher than 50% of the wafer thickness H from the bottom 20. For this reason, the position of the center of gravity of the wafer W is equal to or lower than the height of the side wall contact K and is lower than the height of the main surface 5. For this reason, the wafer W is prevented from jumping out of the pocket portion 10 </ b> A or exceeding the side wall portion 30 and protruding from the pocket portion 10 </ b> A. As a result, since the wafer W is heated uniformly, a film with good quality can be formed.

  According to the wafer holder of the present invention, the angle θ is not less than 10 degrees and not more than 45 degrees. When the angle θ is 10 degrees or more, the airflow S can easily travel along the inclination of the upper side wall 32. Therefore, the wafer W can be more suitably transferred. When the angle θ is 45 degrees or less, even if the end portion of the wafer W is applied to the side wall upper portion 32, the end portion of the wafer W immediately falls into the pocket portion 10A. As a result, the wafer W is further suppressed from protruding from the pocket portion 10A. Further, as compared with the case where the angle θ is larger than 45 degrees, the end portion of the wafer W is likely to hit the side wall upper portion 32, and the wafer W can be further suppressed from jumping out of the pocket portion 10A.

  According to the wafer holder of the present invention, when the center O of the bottom portion 20 and the center of the bottom surface of the wafer W are matched, the distance L from the side wall lower portion 34 to the side surface of the wafer W is 0.25 mm or more and 0.5 mm or less. is there. When the distance L is 0.25 mm or more, the distance between the non-contact transfer device 100 and the wafer W and the side wall portion 30 is increased, so that the airflow S hitting the side wall portion 30 is not contacted. And backflow into the gap between the wafer W and the wafer W can be further suppressed. When the distance L is 0.5 mm or less, the distance between the wafer W and the side wall portion 30 is shortened. Thus, the wafer W does not move greatly in the pocket portion 10A, and the non-contact transfer device 100 can be easily aligned with the wafer W. Thereby, the wafer W can be conveyed more suitably. Further, during the film forming process, the wafer W is heated at substantially the same position, so that it is heated evenly. Thereby, a film with good quality can be formed.

  According to the wafer holder 1 </ b> B according to the present invention, the protrusion 50 that protrudes from the side wall 30 and can contact the side surface of the wafer W is formed in a plan view perpendicular to the main surface 5. Since the space between the wafer W and the side wall portion 30 can be secured by the protrusion 50, the airflow S can be further suppressed from flowing back into the gap between the non-contact transfer apparatus 100 and the wafer W. Further, the protrusion 50 prevents the wafer W from being heated while being in contact with the side wall 30 during the film formation process. The wafer W is heated more evenly because the movement of heat through the side wall portion 30 is suppressed. Thereby, a film with good quality can be formed.

  According to the wafer holder 1B according to the present invention, the projection tip 56 is formed in an arc shape in plan view. Even if the side surface of the wafer W comes into contact with the protrusion front end portion 56, the protrusion front end portion 56 has an arc shape, so that stress can be prevented from concentrating on the side surface of the wafer W. As a result, it is possible to suppress degradation of the quality of the wafer W.

  According to the wafer holder 1B according to the present invention, the radius of curvature R1 of the protrusion tip 56 is 0.5 mm or more in plan view. Thereby, it can suppress more that stress concentrates on the side of wafer W.

  According to the wafer holder 1B according to the present invention, the projection end 58 is formed in an arc shape in a plan view, and the curvature radius R2 of the projection end 58 is 10 mm or more. Since the connecting portion between the protruding portion 50 and the side wall portion 30 is increased, the connection strength between the protruding portion 50 and the side wall portion 30 is increased. As a result, even when the wafer W comes into contact with the protrusion 50, the protrusion 50 is suppressed from coming off from the root, that is, near the connection portion between the protrusion 50 and the side wall 30.

  According to the wafer holder 1B according to the present invention, three or more protrusions 50 are formed, and the interval between the protrusions 50 is constant. Further, in plan view, the protrusions 50 are arranged point-symmetrically with respect to the center O of the bottom 20. Thereby, in the pocket portion 10 </ b> A, no matter which direction the wafer W moves, the protrusion 50 is brought into contact with or easily formed, so that a space between the wafer W and the side wall portion 30 can be secured.

  According to the wafer holder of the present invention, the wafer holder is made of silicon carbide. Since the light carbonization is excellent in thermal conductivity, the wafer W can be heated uniformly. For this reason, a film with good quality can be formed.

(4) Other Embodiments Although the contents of the present invention have been disclosed through the embodiments of the present invention, it should not be understood that the description and drawings constituting a part of this disclosure limit the present invention. The present invention includes various embodiments not described herein.

  For example, the side wall lower part 34 is formed in parallel with the straight line m, but it is not always necessary. The side wall lower portion 34 may not be parallel to the straight line m. Further, the side wall lower portion 34 may be formed such that a portion connecting the side wall lower portion 34 and the bottom portion 20 has an arc shape in the cross section of the pocket portion 10A.

  In addition, in the wafer holder 1B, the protrusion 50 is inclined, but it is not always necessary. The protrusion 50 may not be inclined. That is, the angle φ may be 0 degrees. As shown in FIG. 7, even if the protrusion 50 is not inclined, the airflow S that hits the protrusion 50 flows from the protrusion 50 to the upper side wall 32 and toward the main surface 5 from the pocket 10 </ b> A. Flowing. For this reason, the airflow S hitting the protrusion 50 does not flow backward into the gap between the non-contact transfer apparatus 100 and the wafer W, and the wafer W can be transferred appropriately using the non-contact transfer apparatus 100.

  As described above, the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  DESCRIPTION OF SYMBOLS 1A, 1B ... Wafer holder, 5 ... Main surface, 10A, 10B ... Pocket part, ... Pocket part, 20 ... Bottom part, 30 ... Side wall part, 32 ... Side wall upper part, 34 ... Side wall lower part, 50 ... Projection part, 52 ... Projection upper part 54 ... Projection lower part, 56 ... Projection tip, 58 ... Projection end, 100 ... Non-contact conveying device, 110 ... Cushion chamber, 112 ... Delivery port, 117 ... Jet port, K ... Side wall contact, K '... Projection contact , O ... center, P, P '... main surface contact, S ... air current, W ... wafer

Claims (10)

A wafer holder having a main surface and holding a wafer,
A concave pocket is formed on the main surface,
The pocket portion is constituted by a bottom portion on which the wafer is placed, and a side wall portion continuous with the main surface and the bottom portion,
The depth from the main surface to the bottom is deeper than 50% of the wafer thickness, which is the thickness of the wafer,
The side wall has a side wall upper part continuous with the main surface, a side wall upper part and a side wall lower part continuous with the bottom part,
In a cross section passing through the center of the bottom and perpendicular to the main surface, a side wall contact that is a contact between the upper side wall and the lower side wall is higher than 50% of the wafer thickness from the bottom, and is opposite to the bottom. In a range lower than the wafer surface,
When a contact between the main surface and the upper portion of the side wall is a main surface contact, and an axis that passes through the center of the bottom and is perpendicular to the main surface is a central axis,
In the cross section, the upper portion of the side wall is an inclined wafer holder so that the main surface contact is further away from the central axis than the side wall contact.   2. The wafer holder according to claim 1, wherein in the cross section, an angle centered on the side wall contact formed by a straight line passing through the side wall contact and perpendicular to the main surface and the upper side wall is 10 degrees or more and 45 degrees or less.   3. The wafer holder according to claim 1, wherein when the center of the bottom portion and the center of the bottom surface of the wafer coincide with each other, a distance from the lower portion of the side wall to the side surface of the wafer is 0.25 mm or more and 0.5 mm or less.   4. The wafer holder according to claim 1, wherein, in a plan view perpendicular to the main surface, a protrusion that protrudes from the side wall and contacts the side surface of the wafer is formed. 5.   The wafer holder according to claim 4, wherein, in the plan view, the tip of the protrusion is formed in an arc shape.   The wafer holder according to claim 5, wherein a radius of curvature of the tip portion is 0.5 mm or more in the plan view.   7. The end of the projection that connects the side wall and the projection in the plan view is formed in an arc shape, and the radius of curvature of the end of the projection is 10 mm or more. The wafer holder of any one of Claims 1. Three or more protrusions are formed,
The wafer holder according to claim 4, wherein the interval between the protrusions is constant. Three or more protrusions are formed,
9. The wafer holder according to claim 4, wherein, in the plan view, the protrusions are arranged point-symmetrically with respect to the center of the bottom. 9.   The wafer holder according to claim 1, wherein the wafer holder is made of silicon carbide.

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