CN213652635U

CN213652635U - Graphite plate and deposition device

Info

Publication number: CN213652635U
Application number: CN202021578280.1U
Authority: CN
Inventors: 林忠宝; 彭伟伦; 李明照
Original assignee: Xiamen Sanan Optoelectronics Technology Co Ltd
Current assignee: Xiamen Sanan Optoelectronics Technology Co Ltd
Priority date: 2019-10-15
Filing date: 2019-10-15
Publication date: 2021-07-09
Anticipated expiration: 2029-10-15
Also published as: CN211284533U

Abstract

The utility model provides a graphite plate and deposition device. The utility model discloses a graphite plate is through increasing protruding quantity in every wafer recess and/or add and be greater than ordinary bellied large tracts of land with epitaxial wafer area of contact and protruding, wafer and bellied area of contact have been increased, still through adjusting each protruding distribution position in the wafer recess simultaneously, frictional force that receives when increasing the wafer rotation jointly, improve the control of wafer recess to the centrifugal force that the epitaxial wafer receives, reduce its skew, avoid causing the increase of the temperature difference that area of contact changes and arouse between wafer and the arch because of the skew, guarantee wafer growth quality, promote the yield. On this basis, the utility model discloses still carry out the design of reordering to the wafer recess of current graphite plate, carry out the removal of different degrees with the wafer recess to the direction of keeping away from the quotation center to increase wafer recess quantity, make graphite plate space utilization rise, effectively promoted the productivity in its single production cycle.

Description

Graphite plate and deposition device

Technical Field

The utility model relates to a chemical vapor deposition equipment technical field especially relates to a graphite plate and deposition apparatus.

Background

In the equipment used in the chemical vapor deposition field, graphite disks are important components for carrying the epitaxial wafers being grown. A conventional graphite plate is usually provided with a plurality of wafer grooves (Pocket Profile) for placing epitaxial wafers, and a protrusion-like structure (Tab) is further provided on an inner wall of each wafer groove for supporting the epitaxial wafer.

In the deposition process, because the graphite disc rotates at a high speed, the existing common wafer groove-protrusion design has poor control on the centrifugal force borne by an epitaxial wafer, the wafer is easy to deviate from the central position of the wafer groove, the contact area between the wafer and the protrusion is changed, so that the edge temperature of the wafer generates large difference, the quality of the wafer is influenced, even the yield of the wafer is reduced, and the production cost is greatly improved.

Secondly, with the increasing demand of epitaxial wafers, the throughput of wafers is also a problem to be solved. At present, graphite discs with 31 wafer grooves are mostly adopted for growing 4-inch epitaxial wafers, namely 31 wafers are produced in a single production cycle, and the productivity of the wafers still needs to be improved.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, it is an object of the present invention to provide a graphite plate and a deposition apparatus. The graphite plate not only solves the problem of poor quality caused by temperature difference generated by the influence of centrifugal force on the edge of the wafer, but also effectively improves the productivity.

In order to achieve the above and other related objects, the present invention provides a graphite plate, comprising: graphite plate base quotation and set up in the quotation top is used for placing the wafer recess of epitaxial wafer, every be provided with a plurality of archs on the wafer recess inside wall, be used for supporting epitaxial wafer, every be provided with at least in the wafer recess 9 protruding.

As a preferable aspect of the present invention, the protrusion includes a first protrusion and/or a second protrusion, an upper surface area of the first protrusion is smaller than an upper surface area of the second protrusion, and a plurality of the first protrusion and at least one of the second protrusion are simultaneously provided on an inner sidewall of at least one of the wafer grooves.

As a preferred scheme of the utility model, the wafer recess includes inner circle wafer recess, well circle wafer recess and outer lane wafer recess, every the inner circle wafer recess and/or well circle wafer recess is provided with at least 10 first protruding, and/or every the outer lane wafer recess is provided with at least 8 first protruding and at least one the second is protruding, just first protruding quantity is the even number.

As an optimized scheme of the utility model, every the direction projection shape of wafer recess in perpendicular quotation is circular, defines the line position of the circular shape centre of a circle and graphite plate quotation central point is 0 of wafer recess, and the angle increases along clockwise, first protruding at least sets up every the inner circle wafer recess and/or on 126 °, 156 °, 204 and 234 of well circle wafer recess position, and/or set up at least every on 126 of outer lane wafer recess and 234 positions, the second is protruding to have at least one to set up between 160 ~200 scope of outer lane wafer recess.

As a preferred scheme of the utility model, every inner circle wafer recess and/or well circle wafer recess are provided with 10 first juts, first jut sets up respectively the inner circle wafer recess and/or well circle wafer recess 30 °, 60 °, 90 °, 126 °, 156 °, 204 °, 234 °, 270 °, 300 ° and 330 ° on the position.

As a preferred scheme of the utility model, every outer lane wafer recess is provided with 8 first protruding and 1 the second is protruding, first protruding setting is respectively in outer lane wafer recess 30 °, 60 °, 90 °, 126 °, 234 °, 270 °, 300 ° and 330 ° in the position, the second is protruding to be set up in outer lane wafer recess 180 ° in the position.

As a preferable aspect of the present invention, the shape of the upper surface of the protrusion includes at least one of a polygon and an arc.

As an optimized scheme of the utility model, the quantity of wafer recess is 32 at least, wherein, inner circle wafer recess sets up to 5 at least and/or well circle wafer recess sets up to 11 at least, outer lane wafer recess sets up to 17 at least.

As a preferable aspect of the present invention, the bottom of the wafer groove includes a flat surface type or a concave surface type.

As an optimized scheme of the utility model, every the direction projection shape of wafer recess perpendicular quotation is circular, protruding top still is provided with a plurality of protruding portions to the extension of circular centre of a circle.

The utility model also provides a deposition device, the device adopts the aforesaid arbitrary graphite plate as the year dish of growth epitaxial wafer.

As above, the utility model discloses a graphite plate and deposition apparatus has following beneficial effect:

(1) the utility model discloses a graphite plate, through increasing protruding quantity in every wafer recess and/or add and be greater than ordinary prominent large tracts of land protrudingly with epitaxial wafer area of contact, wafer and prominent area of contact have been increased to increase the frictional force that receives when the wafer is rotatory, improved the control of wafer recess to the centrifugal force that epitaxial wafer receives, reduced the skew of wafer, avoid causing the increase of the temperature difference that the area of contact between wafer and the protrusion changes and arouse because of the skew, guaranteed the growth quality of wafer; meanwhile, the distribution positions of the protrusions in the wafer groove are adjusted, so that the influence of the wafer deviating from the center of the wafer groove caused by centrifugal force is further reduced. Through foretell improvement, the position of epitaxial wafer when can effectively stabilize graphite plate rotatory reduces its edge because of receiving the temperature difference that centrifugal force influences and produce, guarantees the wafer quality, promotes the yield, reduction in production cost.

(2) Present graphite plate design does not reach best space utilization, the utility model discloses carry out the design of reordering to it, on the basis that whole area of graphite plate and single wafer recess size do not have the change, wafer recess on the graphite plate will have now carries out the removal of not equidimension to the direction of keeping away from the quotation center to increased wafer recess quantity, made the space utilization of graphite plate rise, effectively promoted the productivity in its single production cycle.

Drawings

FIG. 1 is a schematic diagram showing the protrusion distribution in a single wafer pocket of a conventional graphite disk for growing 4 "epitaxial wafers.

Fig. 2 is a schematic view of a single wafer groove structure of a graphite plate according to an embodiment of the present invention.

Fig. 3 is a schematic view of a single wafer groove structure of a graphite plate according to an embodiment of the present invention.

Fig. 4 is a schematic diagram illustrating the distribution of protrusions in a single inner ring wafer groove and/or a middle ring wafer groove of a graphite disk according to an embodiment of the present invention.

Fig. 5 is a schematic view showing the distribution of protrusions in a single outer ring wafer groove of a graphite plate according to an embodiment of the present invention.

Fig. 6 is a schematic structural view of a graphite plate according to an embodiment of the present invention.

Description of reference numerals:

1. a wafer groove; 2. a protrusion; 3. epitaxial wafer; 4. a protrusion; 5. and (3) a step structure.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will be apparent to those skilled in the art from the disclosure herein. The present application is capable of other and different embodiments and its several details are capable of modifications and/or changes in various respects, all without departing from the spirit of the present application. It is to be noted that the features in the following embodiments and examples may be combined with each other without conflict.

Referring to fig. 1 to 6, it should be understood that the drawings provided in the embodiments of the present invention are only schematic illustrations of the basic concepts of the present invention, and although the drawings only show the components related to the present invention, not drawn according to the number, shape and size of the components in actual implementation, the shapes, the quantities and the proportions of the components in actual implementation may be changed at will, and the layout of the components may be more complicated. The structure, ratio, size and the like shown in the drawings are only used for matching with the content disclosed in the specification, so that those skilled in the art can understand and read the content, and do not limit the limit conditions that the present application can be implemented, so that the essence of the technology is not existed, and any structural modification, ratio relationship change or size adjustment should still fall within the scope that the technical content disclosed in the present application can cover without affecting the efficacy and the achievable purpose of the present invention.

At present, the number of wafer grooves 1 for growing 4-inch epitaxial wafers is 31, and each wafer groove 1 is provided with 8 graphite discs with 2 protrusions, wherein the 2 protrusions in each wafer groove 1 are the same; meanwhile, if the projection shape of each wafer groove 1 in the direction perpendicular to the disk surface is circular, the position of the connecting line between the circle center of the circle and the center point of the disk surface of the graphite disk is defined as 0 degree position of the wafer groove 1, and the angle is increased clockwise, 8 protrusions 2 in the graphite disk in the prior art are respectively arranged at the positions of 30 degrees, 90 degrees, 120 degrees, 150 degrees, 210 degrees, 240 degrees, 270 degrees and 330 degrees of the wafer groove, referring to fig. 1, the centrifugal force of an epitaxial wafer is poorly controlled in the actual production of the graphite disk of the type, the wafer is easily deviated from the center position of the wafer groove, so that the edge temperature of the wafer is greatly different, the quality of the wafer is affected, even the yield of the wafer is reduced, and the production cost is greatly improved.

Example one

The present embodiment provides a graphite disc, the graphite disc includes: graphite plate base quotation and set up in quotation top is used for placing epitaxial wafer 3's wafer recess 1, every be provided with a plurality of archs 2 on the 1 inside wall of wafer recess, be used for supporting epitaxial wafer 3 to make have the space of certain interval between wafer 3 and the recess bottom, every be provided with at least 9 in the wafer recess 1 protruding 2.

Optionally, the shape of the upper surface of the protrusion 2 includes at least one of a polygon and an arc.

Optionally, the bottom of the wafer recess 1 comprises a planar or a concave type.

Optionally, a projection of each wafer groove 1 in a direction perpendicular to the disk surface is circular, and a plurality of protrusions 4 extending toward the center of the circular circle are further disposed above the protrusion 2, so as to further fix the position of the epitaxial wafer 3.

In the prior art, the wafer grooves of graphite discs are mainly designed into four types: flat disks (Flat disks), stepped edge disks (Rim disks), protruding edge disks (Tab disks) and both stepped and protruding edge disks (Gear disks). In this embodiment, a protrusion (Tab) in a wafer groove is improved, so that the design of a graphite disc in this embodiment may be applied to a Tab disc and a Gear disc, as shown in fig. 2, the graphite disc is a schematic structural diagram of a single wafer groove 1 in a Gear disc provided with a protrusion 2, wherein the bottom of the wafer groove 1 is a planar bottom and has a step structure 5, and an epitaxial wafer 3 has a diameter the same as that of the bottom of the wafer groove 1 and can be just placed on the protrusion 2 to cover the entire upper surface of the protrusion 2, of course, the placement manner of the epitaxial wafer 3 in the Gear disc is not limited, and the diameter of the epitaxial wafer 3 may be larger than the diameter of the bottom of the wafer groove 1, that is, the epitaxial wafer is placed on the step structure 5 and the protrusion 2; or may be smaller than the diameter of the bottom of the wafer recess 1, i.e. placed on part of the upper surface of the protrusion 2. Meanwhile, a protrusion 4 may be disposed above the protrusion 2, and a schematic structural diagram of the protrusion 4 is shown in fig. 3, and the wafer 3 is disposed between the protrusion 4 and the protrusion 2.

The number of 2 projections in every wafer recess 1 of the graphite dish of 4 cun epitaxial wafer of present growth is 8, and 2 projections of every wafer recess 1 in the graphite dish of this embodiment all increase, through increasing 2 quantity of projection, the area of contact of wafer 3 with 2 projections has been increased, and then 3 frictional force that receive of wafer when having increased the high-speed rotation of graphite dish, wafer 3's position has been stabilized, thereby it receives the marginal temperature difference influence that centrifugal force leads to reduce it, improve wafer 3's growth quality. In the embodiment, the mode of solving the problem of wafer quality and yield caused by temperature difference caused by the influence of centrifugal force on the edge of the wafer in the graphite disc by increasing the number of the protrusions is not limited to be applied to the existing graphite disc for growing 4-inch epitaxial wafers, and the mode can be applied to the graphite discs for growing wafers with other sizes according to actual conditions.

Example two

The present embodiment provides a graphite disc, whose basic structure is the same as that in the first embodiment, and is not described herein again, and the difference between the graphite disc and the first embodiment is as follows: in this embodiment, the protrusion 2 includes a first protrusion and/or a second protrusion, an upper surface area of the first protrusion is smaller than an upper surface area of the second protrusion, and a plurality of first protrusions and at least one second protrusion are simultaneously disposed on an inner sidewall of at least one wafer recess 1 in the wafer recess 1.

As an implementation manner of this embodiment, the wafer grooves 1 include an inner ring wafer groove, a middle ring wafer groove, and an outer ring wafer groove, each inner ring wafer groove and/or the middle ring wafer groove is provided with at least 10 first protrusions, and/or each outer ring wafer groove is provided with at least 8 first protrusions and at least one second protrusion, and the number of the first protrusions is even. When the graphite disc rotates, the centrifugal force applied to the wafer 3 in the outer ring wafer groove is strongest, and compared with the wafer groove-protrusion structures of the inner ring and the middle ring, the control of the centrifugal force applied to the wafer 3 by the outer ring wafer groove-protrusion structures is relatively poorer, the wafer 3 is more prone to deviating from the central position of each wafer groove 1, and then the edge of the wafer generates larger temperature difference, therefore, in the implementation mode, at least one protrusion 2 with a larger contact area with the wafer 3 is preferably arranged in the outer ring wafer groove, so that the contact area of the wafer 3 and the protrusion 2 is increased, and the deviation of the wafer 3 is reduced. Of course, the arrangement of the second protrusion is not limited to the example in this implementation, and the second protrusion may also be arranged in the inner ring wafer groove and/or the middle ring wafer groove.

The protrusions 2 in each wafer groove 1 of the existing 4-inch epitaxial wafer graphite disc are the same protrusions, the areas of the upper surfaces of the protrusions are the same, large-area protrusions with the contact area larger than that of the common protrusions are arranged in the wafer groove 1 of the graphite disc, so that the friction force borne by the wafer 3 during rotation can be increased, the deviation of the wafer 3 is reduced, the increase of temperature difference caused by the change of the contact area between the wafer 3 and the protrusions 2 due to the deviation is avoided, and the growth quality of the wafer 3 is improved. In the embodiment, the mode of solving the problem of wafer quality and yield caused by temperature difference generated by the influence of centrifugal force on the edge of the wafer in the graphite disc is not limited to be applied to the existing graphite disc for growing 4-inch epitaxial wafers by adding the large-area bulge, which has a larger contact area with the epitaxial wafer than the common bulge, and the mode can be applied to the graphite disc for growing wafers with other sizes according to actual conditions.

EXAMPLE III

The present embodiment provides a graphite disc, whose basic structure is the same as that in the second embodiment, and is not described herein again, and the difference between the graphite disc and the second embodiment is as follows: the projection shape of each wafer groove 1 in the direction vertical to the disc surface is circular, the position of a connecting line between the circle center of the circle and the central point of the disc surface of the graphite disc is defined as 0 degree position of the wafer groove 1, the angle is increased along the clockwise direction, the first protrusions are at least arranged at the positions of 126 degrees, 156 degrees, 204 degrees and 234 degrees of each inner ring wafer groove and/or the middle ring wafer groove, and/or at least arranged at the positions of 126 degrees and 234 degrees of each outer ring wafer groove, and at least one second protrusion is arranged between 160 degrees and 200 degrees of the outer ring wafer groove.

As an implementation manner of this embodiment, as shown in fig. 4 and 5, each of the inner ring wafer grooves and/or the middle ring wafer groove is provided with 10 first protrusions, and the first protrusions are respectively disposed at positions of 30 °, 60 °, 90 °, 126 °, 156 °, 204 °, 234 °, 270 °, 300 °, and 330 ° of the inner ring wafer groove and/or the middle ring wafer groove; each outer ring wafer groove is provided with 8 first protrusions and 1 second protrusion, the first protrusions are respectively arranged at the positions of 30 degrees, 60 degrees, 90 degrees, 126 degrees, 234 degrees, 270 degrees, 300 degrees and 330 degrees of the outer ring wafer groove, and the second protrusions are arranged at the positions of 180 degrees of the outer ring wafer groove. Furthermore, the upper surface of the first protrusion is triangular, and the upper surface of the second protrusion is knife-edge shaped.

In the existing graphite disk for growing 4-inch epitaxial wafers, 8 protrusions 2 of each wafer groove 1 are respectively arranged at positions of 30 °, 90 °, 120 °, 150 °, 210 °, 240 °, 270 ° and 330 ° of the wafer groove. In the embodiment, the positions of the protrusions 2 of the wafer groove 1 are rearranged, and a part of the protrusions 2 is adjusted to a position farther from the center of the graphite disk, for example, in the implementation manner of the embodiment, the arrangement of four protrusions at 126 °, 156 °, 204 °, and 234 ° in the inner ring wafer groove and/or the arrangement of three protrusions at 126 °, 234 °, and 180 ° in the outer ring wafer groove are more biased in the direction far from the center of the graphite disk than the protrusions at 120 °, 150 °, 210 °, and 240 ° in the existing graphite disk wafer groove 1, and since the wafer 3 is biased in the outermost direction far from the center of the graphite disk by the centrifugal force during the rotation of the graphite disk, the design can make the protrusions 2 more concentrated at the position where the wafer 3 is prone to bias, and further increase the friction force borne by the wafer 3, thereby reducing the edge temperature difference caused by the influence of the centrifugal force and improving the growth quality of the wafer 3. Meanwhile, the second protrusion with larger upper surface area is arranged in the wafer groove of the outer ring at the position of 180 degrees, namely the contact area of the protrusion 2 and the wafer 3 is further increased at the position farthest from the center of the graphite plate, and the deviation of the wafer 3 is cooperatively reduced. In this embodiment, the method for solving the problem of wafer quality and yield caused by the temperature difference at the edge of the wafer due to the centrifugal force in the graphite disc is not limited to be applied to the existing graphite disc for growing 4-inch epitaxial wafers, and the method can be applied to the graphite disc for growing wafers of other sizes according to actual conditions.

Example four

The present embodiment provides a graphite disc, whose basic structure is the same as that in the previous embodiment, and is not described herein again, and the difference between the graphite disc and the previous embodiment is as follows: in this embodiment, the number of the wafer grooves 1 is at least 32, wherein the number of the inner ring wafer grooves is at least 5, the number of the middle ring wafer grooves is at least 11, and the number of the outer ring wafer grooves is at least 17.

As an implementation manner of this embodiment, as shown in fig. 6, the number of the wafer grooves 1 is set to 33, wherein the number of the inner ring wafer grooves is set to 5, the number of the middle ring wafer grooves is set to 11, and the number of the outer ring wafer grooves is set to 17.

At present, the graphite discs with the number of wafer grooves of 31 are mostly adopted for growing 4-inch epitaxial wafers, and the graphite discs are rearranged in the embodiment, so that the wafer grooves on the existing graphite discs are moved to different degrees in the direction away from the center of the disc surface on the basis that the whole area of the graphite discs and the size of a single wafer groove are not changed, the number of the wafer grooves is increased, the space utilization rate of the graphite discs is increased, and the capacity of the graphite discs in a single production cycle is improved. In addition, because the wafer groove moves outwards, the centrifugal force borne by the wafer can be correspondingly increased, and by matching with some improvements on the protrusion of the wafer groove in the embodiment, the influence of the centrifugal force can be effectively reduced, and the growth quality of the wafer can be ensured while the productivity is improved.

EXAMPLE five

This embodiment provides a deposition apparatus that employs the graphite disk of any of the above embodiments as a carrier disk for growing epitaxial wafers.

To sum up, the utility model provides a graphite plate and deposition apparatus. The utility model discloses a graphite plate is through increasing protruding quantity in every wafer recess and/or add and be greater than ordinary bellied large tracts of land protrudingly with epitaxial wafer area of contact, wafer and bellied area of contact have been increased, still through adjusting the distribution position of each protruding in the wafer recess simultaneously, frictional force that receives when increasing the wafer rotation jointly, improve the control of wafer recess to the centrifugal force that the epitaxial wafer receives, the position of epitaxial wafer when the graphite plate is rotatory has effectively been stabilized, reduce its skew, avoid causing the increase of the temperature difference that wafer and protruding between area of contact change arouse because of the skew, the growth quality of wafer has been guaranteed, the yield has been promoted, still reducible production cost. On this basis, the utility model discloses still carried out the design of reordering to the wafer recess of current graphite plate, on the basis that whole area of graphite plate and single wafer recess size do not have the change, the wafer recess on the graphite plate that will have now has carried out the removal of not equidimension to the direction of keeping away from the quotation center to increased the quantity of wafer recess, made the space utilization of graphite plate rise, promoted the productivity in its single production cycle. The utility model discloses still provide a deposition device simultaneously, the device adopts the utility model provides a graphite plate is as the dish of carrying of growth epitaxial wafer. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely exemplary to illustrate the structure and efficacy of the present invention, and are not intended to limit the present invention. Modifications and variations can be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which may be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A graphite disk, comprising: graphite plate base quotation and set up in the quotation top is used for placing the wafer recess of epitaxial wafer, every be provided with a plurality of archs on the wafer recess inside wall, be used for supporting epitaxial wafer, protruding including first protruding and second are protruding, first protruding upper surface area is less than the protruding upper surface area of second has at least and is provided with simultaneously on the inside lateral wall of a wafer recess first protruding with the second is protruding.

2. The graphite tray of claim 1, wherein at least one of the wafer pocket interior sidewalls is simultaneously provided with a plurality of the first projections and at least one of the second projections.

3. The graphite disc of claim 1, wherein the wafer grooves include an inner ring wafer groove, a middle ring wafer groove, and an outer ring wafer groove, and the at least one wafer groove is the outer ring wafer groove.

4. A graphite disc according to claim 1 or 3, wherein the wafer grooves comprise an inner ring wafer groove, a middle ring wafer groove and an outer ring wafer groove, each inner ring wafer groove and/or the middle ring wafer groove is provided with at least 10 first protrusions, and/or each outer ring wafer groove is provided with at least 8 first protrusions and at least one second protrusion, and the number of the first protrusions is an even number.

5. The graphite disc of claim 3, wherein each wafer groove is circular in projection shape in a direction perpendicular to the disc surface, a connecting line between a center point of the circle and a center point of the disc surface of the graphite disc is defined to be at a position of 0 ° of the wafer groove, an angle increases in a clockwise direction, the first protrusion is disposed at least at positions of 126 °, 156 °, 204 ° and 234 ° of each inner ring wafer groove and/or the middle ring wafer groove, and/or at least at positions of 126 ° and 234 ° of each outer ring wafer groove, and at least one of the second protrusions is disposed between 160 ° and 200 ° of each outer ring wafer groove.

6. The graphite disc of claim 3, wherein each of the inner ring and/or middle ring wafer grooves is provided with 10 of the first protrusions provided at positions 30 °, 60 °, 90 °, 126 °, 156 °, 204 °, 234 °, 270 °, 300 °, and 330 °, respectively.

7. The graphite disc of claim 3, wherein each outer ring wafer groove is provided with 8 first protrusions and 1 second protrusion, the first protrusions being provided at positions 30 °, 60 °, 90 °, 126 °, 234 °, 270 °, 300 ° and 330 ° of the outer ring wafer groove, respectively, and the second protrusions being provided at positions 180 ° of the outer ring wafer groove.

8. The graphite disc of claim 1, wherein the upper surface shape of the protrusions includes at least one of a polygon and an arc.

9. The graphite disc of claim 3, wherein the number of wafer grooves is at least 32, wherein the number of inner ring wafer grooves is at least 5 and/or the number of middle ring wafer grooves is at least 11, and the number of outer ring wafer grooves is at least 17.

10. The graphite tray of claim 1, wherein the bottom of the wafer pocket comprises a planar or concave shape.

11. The graphite disc of claim 1, wherein each wafer groove is circular in projection shape in a direction perpendicular to the disc surface, and a plurality of protrusions extending toward the center of the circle are further provided above the protrusions.

12. A deposition apparatus, characterized in that the apparatus employs a graphite disk as claimed in any one of claims 1 to 11 as a carrier disk for growing epitaxial wafers.