CN211689232U

CN211689232U - Graphite boat and chemical vapor deposition apparatus

Info

Publication number: CN211689232U
Application number: CN201921882325.1U
Authority: CN
Inventors: 申震; 闫志顺; 薛宝达
Original assignee: Beijing Naura Microelectronics Equipment Co Ltd
Current assignee: Beijing Naura Microelectronics Equipment Co Ltd
Priority date: 2019-11-04
Filing date: 2019-11-04
Publication date: 2020-10-16
Anticipated expiration: 2029-11-04

Abstract

The utility model provides a graphite boat and chemical vapor deposition equipment, include the multi-disc boat piece that sets up along the first direction interval, and the first face and the first direction mutually perpendicular that are used for contacting the processed work piece of each boat piece, multi-disc boat piece divide into interior piece group and lie in two sets of outer piece groups of this interior piece group both sides on the first direction, wherein, each outer piece group includes an at least piece boat piece, and for outer piece, interior piece group includes an at least piece boat piece, and is the inner piece, and the thickness of each outer piece on the first direction is greater than the thickness of each inner piece on the first direction. The utility model provides a graphite boat, it not only can reduce the temperature difference between the processed work piece on each boat piece, improves the film thickness homogeneity between each boat piece, can reduce the energy extravagant moreover, improves the productivity.

Description

Graphite boat and chemical vapor deposition apparatus

Technical Field

The utility model relates to a photovoltaic technology field specifically, relates to a graphite boat and chemical vapor deposition equipment.

Background

In the preparation process of a crystalline silicon solar cell, a layer of antireflective passivation film needs to grow on the surface of a silicon wafer, the film is usually prepared by Plasma Enhanced Chemical Vapor Deposition (PECVD) equipment, and specifically, the silicon wafer is loaded into a quartz tube by using a graphite boat for film coating. During film coating, the graphite boat and the silicon wafer are simultaneously positioned in the heated quartz tube, the tube is in a vacuum state, and the external radio frequency power supply is connected with the graphite boat to provide energy required by gas ionization for the graphite boat.

In the process, because the distances between different boat sheets of the graphite boat and the inner wall of the quartz tube are different, the thickness of the plated film of the battery sheet in the same graphite boat generally shows the rule of 'thick edge and thin middle'. The silicon wafers on the outer side of the boat are heated quickly due to the fact that the silicon wafers are close to the quartz tube, so that the temperature of the silicon wafers on the outer side of the boat is higher than that of the silicon wafers on the inner side of the boat during film coating, temperature difference exists among the silicon wafers on the boats, and deposition rates are different.

Further, as the number of silicon wafers loaded in a single boat and the size of the silicon wafers continue to increase, the total weight of the graphite boat is also increasing. The graphite boat can take part in heat absorption as a carrier in the process, the heat absorption of the graphite boat is ineffective for the process, more energy waste is caused, and the graphite boat needs to be cooled before being unloaded at the end of the process, so that the process time is increased, and the productivity is reduced.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least, provide a graphite boat and chemical vapor deposition equipment, it not only can reduce the temperature difference between the work piece of being processed on each boat piece, improves the film thickness homogeneity between each boat piece, can reduce the energy extravagant moreover, improves the productivity.

In order to realize the above-mentioned purpose, the utility model provides a graphite boat, include along the multi-disc boat piece that the first direction interval set up, and each the boat piece be used for the contact by the processing work piece the first face with first direction mutually perpendicular, wherein, multi-disc boat piece is in divide into interior piece group and be located in the first direction two sets of outer piece groups of interior piece group both sides, wherein, each outer piece group includes an at least piece boat piece, and is outer piece, interior piece group includes an at least piece boat piece, and for the inner piece, and each outer piece is in thickness on the first direction is greater than each the inner piece is in thickness on the first direction.

Preferably, the thickness of each of the inner sheets in the first direction is the same.

Preferably, each of the outer sheets has a thickness in the first direction of 2 to 10 mm.

Preferably, each of the outer sheets has a thickness of 4mm in the first direction.

Preferably, each of the inner sheets has a thickness of 1 to 2.5mm in the first direction.

Preferably, each of the inner sheets has a thickness of 2mm in the first direction.

Preferably, the number of outer sheets is 1 sheet for each set of outer sheets.

Preferably, the first surface of each inner sheet comprises at least one sheet bearing area, and a through hole penetrating through the inner sheet along the first direction is formed in a position of the inner sheet corresponding to each sheet bearing area; and the size of the through holes is set so that the sum of the radial cross-sectional areas of all the through holes accounts for 50-90% of the first surface of the inner sheet.

Preferably, the radial section of the through hole is square, and the side length of the square is greater than or equal to 143 mm.

Preferably, the graphite boat further comprises two graphite block groups, the two graphite block groups are respectively located on a boat head side and a boat tail side of each boat sheet in the second direction and connected with each boat sheet, and the second direction is parallel to the first surface and perpendicular to the first direction;

each graphite block group comprises at least one graphite block, each graphite block comprises a middle part divided in the first direction and two edge parts positioned on two sides of the middle part, and the thickness of the middle part in the third direction is smaller than that of each edge part in the third direction; the third direction is parallel to the first surface and perpendicular to the first direction and the second direction.

Preferably, the thickness of the middle portion in the third direction is less than or equal to one half of the thickness of each of the edge portions in the third direction.

Preferably, a connecting rod is inserted in each graphite block in the first direction, and a distance between the connecting rod and an outer surface of the intermediate portion in the third direction is greater than or equal to 3 mm.

The utility model also provides a chemical vapor deposition equipment, including the reaction chamber with the utility model provides an above-mentioned graphite boat, the graphite boat is used for the delivery by the processing work piece.

The utility model has the advantages that:

the utility model provides a graphite boat, it is greater than the thickness of each inner wafer on the first direction through making the thickness of each outer wafer on the first direction, promptly, suitably increase the weight of each outer wafer, reduce the weight of each inner wafer, can make the total weight of graphite boat reduce through the weight that makes the weight that the inner wafer increased be greater than the weight that the outer wafer reduced, thereby can shorten graphite boat intensification and refrigerated time, reduce the required energy of single technology, and then can reduce the energy waste, improve the productivity. Meanwhile, the thickness of each outer plate in the first direction is larger than that of each inner plate in the first direction, so that the heat absorbed by the processed workpiece on the outer plate is less than that absorbed by the processed workpiece on the inner plate, the temperature difference among the processed workpieces on each boat can be compensated, and the uniformity of the film thickness among the boat plates can be improved.

The utility model provides a chemical vapor deposition equipment, it is through adopting the utility model provides an above-mentioned graphite boat not only can reduce the temperature difference between the work piece by processing on each boat piece, improves the film thickness homogeneity between each boat piece, can reduce the energy moreover extravagant, improves the productivity.

Drawings

FIG. 1 is a partial perspective view of a graphite boat according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of one of the boat sheets of the graphite boat according to an embodiment of the present invention;

FIG. 3 is a side view of a graphite boat according to an embodiment of the present invention;

FIG. 4 is a partial dimension view of one of the boat sheets of the graphite boat according to the embodiment of the present invention;

FIG. 5 is a graph showing the temperature change of a conventional graphite boat during the process;

fig. 6 is a temperature variation curve of the graphite boat in the process according to the embodiment of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following describes the graphite boat and the chemical vapor deposition apparatus provided by the present invention in detail with reference to the attached drawings.

Referring to fig. 1 to 3, a graphite boat according to an embodiment of the present invention includes a plurality of boat sheets 1 spaced apart along a first direction (i.e., a Z direction shown in fig. 1 and 3), where the boat sheets 1 are used to carry a workpiece to be processed, for example, when the graphite boat is applied to a process for manufacturing a solar cell, the workpiece to be processed is a silicon wafer. The first direction is generally a radial direction of a quartz tube (used as a reaction chamber), that is, when the graphite boat is transferred into the quartz tube, the boat pieces 1 are arranged at intervals along one radial direction of the quartz tube. Further, the first surface of each boat piece 1 for contacting the workpiece to be processed (i.e., the X-Y surface shown in fig. 1 and 2) is perpendicular to the Z direction. In practical applications, the quartz tube may be placed horizontally, with the Z-direction parallel to the horizontal plane and the X-Y plane perpendicular to the horizontal plane, so that the surface of the workpiece to be machined is also perpendicular to the horizontal plane.

Further, as shown in fig. 3, the plurality of boat pieces 1 are divided in the Z direction into an inner piece group 1a and two outer piece groups 1b located on both sides of the inner piece group 1a, wherein each outer piece group 1b includes one boat piece and is an outer piece 11, the inner piece group 1a includes a plurality of boat pieces and is an inner piece 12, and the thickness of each outer piece 11 in the Z direction is larger than the thickness of each inner piece 12 in the Z direction.

Thus, the total weight of the graphite boat can be reduced by increasing the weight of the inner sheet 12 to be larger than the reduced weight of the outer sheet 11, so that the heating and cooling time of the graphite boat can be shortened, the energy required by a single process can be reduced, the energy waste can be reduced, and the productivity can be improved. Further, the thicker the boat 1 is, the more heat is absorbed at the same time, and the less heat is absorbed by the workpiece to be processed thereon, and therefore, by making the thickness of each outer plate 11 in the Z direction larger than the thickness of each inner plate 12 in the Z direction, the less heat is absorbed by the workpiece to be processed on the outer plate 11 than on the inner plate 12, so that the temperature difference between the workpieces to be processed on each boat 1 can be compensated to some extent, and the uniformity of the film thickness between each boat can be improved.

In the present embodiment, the number of the outer sheets 11 is 1 sheet for each set of the outer sheet groups 1 b. However, the present invention is not limited to this, and in practical applications, the number of the outer sheets 11 may be 2, 3, or 4 or more for each group of the outer sheet groups 1 b. The number of the inner sheets 12 may be set to at least one according to specific needs.

Optionally, the thickness of each inner sheet 12 in the Z-direction is the same for ease of manufacture. However, in actual use, the thickness of each inner sheet 12 in the Z direction may be set to be different depending on the temperature difference between the workpieces to be processed on each inner sheet 12, and specifically, the thickness of each inner sheet 12 may be increased from the inside to the outside by a constant rule.

Optionally, the thickness of each outer sheet 11 in the Z direction is 2-10mm, preferably 4 mm. Within this range, the temperature difference between the workpieces to be processed on the boat pieces 1 can be effectively compensated, and the uniformity of the film thickness between the boat pieces can be improved.

Optionally, each inner sheet 12 has a thickness in the Z direction of 1-2.5mm, preferably 2 mm. In the embodiment, by controlling the thickness of the inner plate 12 within the above range, the heat absorbed by the inner plate 12 at the same time can be reduced, so that the heat of the workpiece to be processed on the inner plate is increased, and the uniformity of the film thickness among the boat plates is further improved; moreover, the reduced thickness of the inner sheet 12 also helps to reduce the overall weight of the graphite boat.

In the present embodiment, as shown in fig. 2, the first surface 121 (i.e., the X-Y surface shown in fig. 2) of each inner sheet 12 includes at least one sheet receiving area, which is an area on the first surface 121 where a workpiece to be processed is located, and through holes 122 penetrating the inner sheet 12 in the first direction (the Z direction in fig. 1) are provided at positions of the inner sheet 12 corresponding to the respective sheet receiving areas. The through holes 122 are sized such that the sum of the radial cross-sectional areas of all the through holes 122 is 50% to 90% of the first surface 121 of the inner sheet 12.

Compared with the prior art, the area of the opening area of the whole inner sheet 12 can be increased to a certain extent, so that the contact area of the boat sheet and the processed workpiece can be reduced, the contact pollution is reduced, and the number of bad sheets can be reduced; meanwhile, the thickness of the boat sheet can be adjusted and controlled, so that the purpose of reducing the weight of the graphite boat is achieved, the heating and cooling time of the graphite boat can be further shortened, the energy required by a single process is reduced, the energy waste can be effectively reduced, and the productivity is improved.

Alternatively, as shown in fig. 4, the radial section (parallel to the X-Y plane) of the through hole 122 is a square, and the side length of the square is greater than or equal to 143 mm. Within the range, the contact area of the boat sheet and the processed workpiece can be reduced by at least 50 percent compared with the prior art, thereby effectively reducing the contact pollution. According to statistics, the graphite boat in the prior art generates more than 12 bad wafers after being prepared by films of 2000 silicon wafers, while the graphite boat adopted in the embodiment generates 0 bad wafers after being prepared by films of 2000 silicon wafers. Therefore, the graphite boat adopted by the embodiment can effectively reduce the number of bad sheets.

In this embodiment, as shown in fig. 4, three fastening points (41, 42, 43) are further disposed on the first surface 121 of the inner sheet 12, and are respectively disposed outside three sides of the through hole 122 to limit the workpiece to be processed in the receiving area. Compared with the prior art, as the size of the through hole 122 changes, the positions of the three clamping points (41, 42, 43) on the inner sheet 12 also change correspondingly, specifically, the height of the geometric center of the clamping point 41 from the bottom edge of the inner sheet 12 (i.e., the lower edge of the inner sheet 12 in fig. 4) is 132.4mm, and the height from the edge of the through hole 122 where the clamping point 41 is located is 8.3 mm; the height of the geometric center of the clamping point 42 from the bottom edge of the inner sheet 12 is 62.6mm, and the height from the edge of the through hole 122 where the clamping point 421 is located is 7.3 mm; the height of the geometric center of the click 43 from the bottom edge of the inner sheet 12 is 14.4mm and 8mm from the edge of the through hole 122 where the click 43 is located. In addition, the bottom edge of the through hole 122 is inclined by 3 degrees relative to the bottom edge of the inner sheet 12 so as to ensure that the workpiece to be machined can be clamped on three clamping points.

In practical applications, in order to avoid the back surface of the workpiece to be processed on the inner sheet 12 adjacent to the outer sheet 11 from being coated accidentally, the workpiece to be processed is not usually carried on the outer sheet 11, and no through hole is provided on the outer sheet 11, that is, the entire structure of the outer sheet 11 is a solid flat plate structure. Of course, if each outer sheet group 1b includes a plurality of outer sheets 11, only the outermost outer sheet 11 may be designed to be a solid flat plate structure, and the remaining outer sheets 11 may be provided with through holes to reduce the thickness of the graphite boat.

Optionally, as shown in fig. 1, the graphite boat further includes two sets of graphite block groups, and the two sets of graphite block groups are respectively located on the boat head side and the boat tail side of each boat sheet 1 in the second direction, and are connected to each boat sheet 1. This second direction is the X direction shown in fig. 1 and 2, which is parallel to the first face 111 of the outer sheet 11 (or the first face 121 of the inner sheet 12) and perpendicular to the Z direction.

Each graphite block group all includes at least one graphite block 2, and in this embodiment, boat head side and boat tail side all are provided with two graphite blocks 2. The two graphite blocks 2 are arranged at intervals in the Y direction and respectively correspond to the middle position and the lower edge position of the side edge of the boat sheet 1 in the Y direction. It should be noted that, for any two adjacent boat sheets 1, the boat head side of one boat sheet 1 and the boat tail side of the other boat sheet 1 are located on the same side, and the first surfaces of the two adjacent boat sheets 1, which are in contact with the workpiece to be processed, are arranged oppositely, so that the two workpieces to be processed located on the two adjacent boat sheets 1 are arranged back to back.

Furthermore, a first connecting portion and a second connecting portion are respectively disposed on the boat head side and the boat tail side of each boat sheet 1, as shown in fig. 1, for the same boat sheet 1, the first connecting portion and the second connecting portion are respectively located at the middle position and the lower edge position close to the side edge of the boat sheet 1 in the Y direction, and for any two adjacent boat sheets 1, the first connecting portion of one boat sheet 1 and the second connecting portion of the other boat sheet 1 are located at the same side and are respectively inserted into two graphite blocks 2.

As shown in fig. 3, on the boat head side (or boat tail side) of each boat sheet 1, each graphite block 2 includes a middle portion 21 divided in the Z direction and two edge portions 22 located on both sides of the middle portion 21, wherein the thickness of the middle portion 21 in the third direction is smaller than the thickness of each edge portion 22 in the third direction. The third direction is a Y direction shown in fig. 3, and the Y direction is parallel to the first surface 111 of the outer sheet 11 (or the first surface 121 of the inner sheet 12) and perpendicular to the Z direction and the X direction.

Since the thickness of the graphite block 2 in the Y direction affects the gas flow rate and the flow rate ratio between the boat pieces 1, that is, the smaller the thickness, the more advantageous the gas flow rate is to increase and the flow rate is to increase, and therefore, by making the thickness of the middle portion 21 of the graphite block 2 in the Y direction smaller than the thickness of the edge portions 22 in the Y direction, the gas flow rate between the boat pieces 1 in the region corresponding to the middle portion 21 can be made higher than the gas flow rate between the boat pieces 1 in the region corresponding to the edge portions 22, so that the deposition rate in the region corresponding to the middle portion 21 can be further increased and the uniformity of the coating thickness can be improved. In addition, the thickness of the middle part 21 of the graphite block 2 in the Y direction is reduced, the weight of the graphite boat can be reduced, the heating and cooling time of the graphite boat can be further shortened, the energy required by a single process is reduced, the energy waste can be reduced, and the productivity is improved.

Optionally, the thickness of the middle portion 21 in the Y direction is less than or equal to one-half the thickness of each edge portion 22 in the Y direction. Within this range, the deposition rate in the region corresponding to the intermediate portion 21 can be effectively increased, and the uniformity of the coating thickness can be improved.

In the present embodiment, a connecting rod 3 is inserted into each graphite block 2 in the Z direction, and the connecting rod 3 is usually made of a ceramic material to reinforce the graphite block 2 and to fixedly connect the graphite block 2 to each boat piece 1. And the distance between the connecting rod 3 and the outer surface of the middle portion 21 of the graphite block 2 in the Y direction is 3mm or more to ensure that the connecting rod 3 does not separate from the middle portion 21 of the graphite block 2.

It is found through experiments that the total weight of the graphite boat can be reduced to 16kg by reducing the thickness of the inner sheet 12 in the Z direction, increasing the size of the through holes 122 of the inner sheet 12, and reducing the thickness of the middle portion 21 of the graphite block 2 in the Y direction, and the graphite boat weighing 16kg in the present embodiment and the graphite boat weighing 23.9kg in the prior art are processed separately, and the process results of the two are compared.

Specifically, the process temperature of the coating process using the PECVD apparatus is about 500 ℃, the maximum heating power of the PECVD apparatus is about 60kW, and in the case of the full power, the energy required for the temperature of the graphite boat with the weight of 16kg in the present embodiment to rise from room temperature (25 ℃) to 500 ℃ is about 2664275J (the specific heat capacity of graphite is 710J/kg · K), and the time taken is 46 s. The graphite boat of the prior art with the weight of 23.9kg takes about 150 s.

As shown in FIG. 5, the graphite boat with a weight of 23.9kg in the prior art takes about 15min during the temperature decreasing process from 500 ℃ and about 13.5min during the temperature re-increasing process to 500 ℃; in contrast, as shown in FIG. 6, the time taken for the temperature of the graphite boat weighing 16kg in this example to decrease from 500 ℃ and to increase again to about 500 ℃ is within 10 min.

Therefore, after the whole weight of the graphite boat is reduced, the time for heating and cooling the graphite boat can be shortened, and the energy required by a single process is reduced, so that the energy waste can be reduced, and the productivity can be improved.

To sum up, the embodiment of the utility model provides a graphite boat, it is greater than the thickness of each inner wafer on the first direction through making the thickness of each outer wafer on the first direction, promptly, suitably increase the weight of each outer wafer, reduce the weight of each inner wafer, can make the total weight of graphite boat reduce through the weight that makes the inner wafer increase be greater than the weight that the outer wafer reduces to can shorten graphite boat intensification and refrigerated time, reduce the required energy of single technology, and then can reduce the energy waste, improve the productivity. Meanwhile, the thickness of each outer plate on the outermost side in the first direction is larger than that of each inner plate in the first direction, so that the heat absorbed by the processed workpiece on the outer plate is smaller than that absorbed by the processed workpiece on the inner plate, the temperature difference among the processed workpieces on the boat plates can be compensated, and the uniformity of the film thickness among the boat plates can be improved.

As another technical scheme, the embodiment of the utility model provides a chemical vapor deposition equipment is still provided, it includes reaction chamber and the graphite boat that is used for the delivery to be processed the work piece, and this graphite boat adopts the embodiment of the utility model provides an above-mentioned graphite boat.

The embodiment of the utility model provides a chemical vapor deposition equipment, it is through adopting the utility model provides an above-mentioned graphite boat not only can reduce the temperature difference between the work piece of being processed on each boat piece, improves the film thickness homogeneity between each boat piece, can reduce the energy extravagant moreover, improves the productivity.

The chemical vapor deposition equipment is, for example, a tubular PECVD equipment.

It is to be understood that the above embodiments are merely exemplary embodiments that have been employed to illustrate the principles of the present invention, and that the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.

Claims

1. A graphite boat comprises a plurality of boat sheets arranged at intervals in a first direction, wherein a first surface, used for contacting a workpiece to be processed, of each boat sheet is perpendicular to the first direction, the graphite boat is characterized in that the boat sheets are divided into an inner sheet group and two outer sheet groups located on two sides of the inner sheet group in the first direction, each outer sheet group comprises at least one boat sheet and is an outer sheet, the inner sheet group comprises at least one boat sheet and is an inner sheet, and the thickness of each outer sheet in the first direction is larger than that of each inner sheet in the first direction.

2. The graphite boat of claim 1, wherein the thickness of each of the inner sheets in the first direction is the same.

3. The graphite boat of claim 1, wherein each of the outer sheets has a thickness in the first direction of 2-10 mm.

4. The graphite boat of claim 3, wherein each of the outer sheets has a thickness of 4mm in the first direction.

5. The graphite boat of claim 1, wherein each of the inner sheets has a thickness in the first direction of 1-2.5 mm.

6. The graphite boat of claim 5, wherein each of the inner sheets has a thickness of 2mm in the first direction.

7. The graphite boat of claim 1, wherein the number of outer sheets for each set of outer sheets is 1 sheet.

8. The graphite boat according to any one of claims 1 to 7, wherein the first surface of each inner sheet comprises at least one sheet-bearing region, and through-holes penetrating the inner sheet in the first direction are provided at positions of the inner sheet corresponding to the respective sheet-bearing regions; and the size of the through holes is set so that the sum of the radial cross-sectional areas of all the through holes accounts for 50-90% of the first surface of the inner sheet.

9. The graphite boat according to claim 8, wherein the through holes have a square shape in radial cross section, and the side length of the square shape is 143mm or more.

10. The graphite boat of any one of claims 1-7, further comprising two sets of graphite blocks respectively located at a leading side and a trailing side of each boat sheet in a second direction and connected to each boat sheet, the second direction being parallel to the first plane and perpendicular to the first direction;

11. The graphite boat of claim 10, wherein the thickness of the middle portion in the third direction is less than or equal to one-half the thickness of each of the edge portions in the third direction.

12. The graphite boat according to claim 10, wherein a connecting rod is pierced in each of the graphite blocks in the first direction, and a spacing between the connecting rod and an outer surface of the intermediate portion in the third direction is greater than or equal to 3 mm.

13. A chemical vapor deposition apparatus comprising a reaction chamber and a graphite boat for carrying a workpiece to be processed, wherein the graphite boat as recited in any one of claims 1 to 12 is used as the graphite boat.