Microwave plasma chemical vapor deposition equipment and method for improving coating quality

Abstract

The invention provides microwave plasma chemical vapor deposition equipment and a method for improving coating quality, and belongs to the technical field of microwaves. The deposition equipment comprises a rack, a cavity, a sample table and a lifting driving device, wherein the rack comprises a discharge cavity bottom plate; and the bottom of the cavity is connected with the upper part of the discharge cavity bottom plate to define a discharge cavity. The sample table is arranged in the discharge cavity, a lifting rod is arranged at the bottom of the sample table, a mounting hole is formed in a bottom plate of the discharge cavity, and the lifting rod slidably penetrates through the mounting hole. The lifting driving device is connected with the bottom of the lifting rod and used for driving the lifting rod to drive the sample table to move up and down. According to the method, the deposition equipment is used, the distribution condition of an electromagnetic field can be improved by moving the sample table up and down by a certain distance, the plasma balls are flatter, the coating thickness can be more uniform, and the coating quality is improved.

Description

Technical Field

[0001] The invention relates to the field of microwave plasma chemical vapor deposition equipment, and in particular to a microwave plasma chemical vapor deposition equipment and a method for improving coating quality. Background Art

[0002] Microwave plasma chemical vapor deposition technology is to use a waveguide to pass the microwaves generated by a microwave generator into the cavity of the reactor through an isolator, and introduce a mixed gas of methane and hydrogen into the cavity. Under the excitation of microwaves, discharge occurs in the cavity to ionize the molecules of the reaction gas and generate plasma. A sample stage is set in the cavity, and a substrate is set on the sample stage. After the reaction gas molecules are ionized, carbon elements will be deposited on the substrate to form a diamond coating. The uniformity of the thickness of the diamond coating is one of the important indicators of the coating quality. The current deposition equipment has an uneven coating thickness, resulting in poor coating quality. Summary of the invention

[0003] The object of the present invention is to provide a microwave plasma chemical vapor deposition device and a method for improving coating quality, which can significantly improve the coating quality.

[0004] The present invention is achieved in that: A microwave plasma chemical vapor deposition device, comprising: A frame, wherein the frame includes a discharge chamber bottom plate; A cavity, the bottom of which is connected to the upper part of the discharge cavity bottom plate to enclose and form a discharge cavity; A sample stage, wherein the sample stage is arranged in the discharge chamber, a lifting rod is arranged at the bottom of the sample stage, a mounting hole is arranged on the bottom plate of the discharge chamber, and the lifting rod can slide through the mounting hole; A lifting drive device is connected to the bottom of the lifting rod and is used to drive the lifting rod to drive the sample platform to move up and down.

[0005] Furthermore, the lifting drive device includes a motor and a transmission assembly, and the motor is connected to the lifting rod through the transmission assembly to drive the lifting rod to move up and down.

[0006] Further, the transmission assembly includes a lifting plate and a plurality of screw rods, and the lifting plate is fixedly connected to the lifting rods; The multiple screw rods are all vertically arranged and rotatably connected to the frame, and the axial movement of the multiple screw rods is restricted; a nut is sleeved on each of the screw rods, and the multiple nuts are fixedly connected to the lifting plate; the motor is transmission-connected to the multiple screw rods and can drive the multiple screw rods to rotate synchronously.

[0007] Furthermore, it also includes a connecting plate, which is arranged between the discharge chamber bottom plate and the lifting plate, and the upper ends of the multiple screw rods are rotatably connected to the connecting plate respectively.

[0008] Furthermore, a sleeve is provided between the connecting plate and the bottom plate of the discharge chamber, the sleeve is sleeved on the lifting rod, the upper end of the sleeve is fixedly connected to the bottom plate of the discharge chamber, and the lower end is fixedly connected to the connecting plate; the lifting rod can movably pass through the connecting plate, and a sealing member is provided between the lifting rod and the connecting plate; and an exhaust hole is provided on the sleeve.

[0009] Furthermore, the lifting rod is swingably connected to the frame, so that the tilt angle of the sample stage can be adjusted.

[0010] Furthermore, a moving block is fixedly connected to the lower part of the lifting rod, and the moving block is arranged on the lifting plate; Pushing blocks are arranged around the moving block, and the pushing blocks are fixedly connected to the lifting plate. Each of the pushing blocks is provided with a pushing screw. Rotating the pushing screw in a first direction can make the pushing screw abut against the moving block and push the moving block to move. Rotating the pushing screw in a direction opposite to the first direction can separate the pushing screw from the moving block.

[0011] Furthermore, an inner cavity plate is also provided in the discharge cavity, and the inner cavity plate is slidably matched with the inner wall of the cavity; An inner bellows and an outer bellows are provided between the inner plate and the discharge chamber bottom plate, the inner bellows is sleeved on the lifting rod, and the outer bellows is sleeved on the inner bellows; the upper ends of the inner bellows and the outer bellows are both sealedly connected to the inner plate, and the lower ends of the inner bellows and the outer bellows are both sealedly connected to the discharge chamber bottom plate, and a containing space is formed between the inner bellows and the outer bellows; The discharge cavity bottom plate is provided with an exhaust hole, which is communicated with the accommodating space and is used for connecting an exhaust pipe.

[0012] Furthermore, the inner and outer sides of the inner bellows and the outer bellows are both provided with shaped telescopic tubes for reducing the radial deformation of the inner bellows and the outer bellows.

[0013] A method for improving coating quality, using the microwave plasma chemical vapor deposition equipment, comprises the following steps: Real-time detection of the temperature at the center and four directions of the edge of the sample stage; When the temperature at the center of the sample stage is higher than the average temperature at the edge of the sample stage, the sample stage is raised by a preset distance. After continuing to monitor for a preset time, when the temperature at the center of the sample stage is still higher than the average temperature at the edge of the sample stage, the height of the cavity plate is lowered. The temperatures of two opposite positions on the edge of the sample stage are the first temperature and the second temperature respectively. When the difference between the first temperature and the second temperature is greater than a preset difference, the inclination angle of the sample stage is adjusted so that the position corresponding to the lower temperature of the first temperature and the second temperature of the sample stage moves a preset distance in the direction away from the plasma ball.

[0014] The beneficial effects of the present invention are: The microwave plasma chemical vapor deposition equipment and the method for improving the coating quality obtained by the above design of the present invention, when in use, when the temperature measured by the thermometer at the center of the sample stage is higher than the average temperature at the edge, it means that the temperature at the center of the sample stage is too high. The inventor has found through research that the temperature at the center of the sample stage is too high, indicating that the plasma ball is not flat enough, that is, the electromagnetic field at the center is too strong and the edge is relatively weak; the electromagnetic field distribution is one of the important factors affecting the uniformity of the coating thickness. At this time, moving the sample stage upward by a certain distance can improve the electromagnetic field distribution, making the plasma ball flatter, and then making the coating thickness more uniform, thereby improving the coating quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a cross-sectional view of a deposition apparatus provided in an embodiment of the present invention; Figure 2 is a perspective view of a deposition apparatus provided in an embodiment of the present invention; Figure 3 is a top view of a sample stage of a deposition device provided in an embodiment of the present invention; Figure 4 It is a curve diagram showing the temperature at the edge of the sample stage changing with the distance between the edge of the sample stage and the plasma ball when the deposition device provided by the embodiment of the present invention is working.

[0016] Icons: 1-deposition equipment; 11-chamber; 121-discharge chamber bottom plate; 1211-exhaust hole; 122-connecting plate; 13-sample stage; 14-lifting rod; 15-lifting drive device; 151-motor; 152-lifting plate; 153-screw; 154-nut; 155-belt; 16-sleeve; 17-moving block; 18-push block; 181-push screw; 191-chamber plate; 192-inner bellows; 193-outer bellows; 194-shaped telescopic tube; 2-plasma ball. DETAILED DESCRIPTION Embodiment 1:

[0017] Please refer to Figure 1-Figure 3The present embodiment provides a microwave plasma chemical vapor deposition device 1, which includes a frame, a cavity 11 and a sample stage 13, wherein the cavity 11 is fixedly mounted on the discharge cavity bottom plate 121 of the frame, and the sample stage 13 is arranged in the cavity 11. During discharge, the electromagnetic field is mainly distributed on the upper part of the sample stage 13, and its shape is an ellipsoid, commonly known as a plasma ball. The inventors have found through research that the flatter the plasma ball is, the higher the uniformity of the substrate coating on its sample stage 13. The inventors have further found that the distance between the sample stage 13 and the plasma ball can affect the flatness of the plasma ball 2; that is, by adjusting the height of the sample stage 13, the flatness of the plasma ball 2 can be adjusted.

[0018] In order to adjust the height of the sample stage 13, the deposition device 1 is further provided with a lifting drive device 15; the bottom of the sample stage 13 is connected to the lifting drive device 15 through a lifting rod 14. The lifting drive device 15 is used to drive the sample stage 13 to move up and down, thereby adjusting the distribution of the electromagnetic field in the cavity 11, so that the plasma ball 2 is flatter.

[0019] In addition, the deposition device provided in this embodiment can also adjust the inclination angle between the sample stage 13 and the discharge chamber bottom plate 121. By adjusting the inclination angle of the sample stage 13, the distance between each position (position A, position B, position C, position D, position E) on the sample stage 13 and the plasma ball 2 can be changed; thereby making the temperature distribution of each position on the sample stage 13 more uniform, thereby improving the coating quality.

[0020] Specifically, the cavity 11 is a cylindrical structure, and its bottom is fixedly connected to the discharge cavity bottom plate 121 of the frame; the cavity 11 and the discharge cavity bottom plate 121 enclose a discharge cavity. A mounting hole is provided in the middle of the discharge cavity bottom plate 121, and the outer diameter of the lifting rod 14 at the bottom of the sample stage 13 is smaller than the inner diameter of the above-mentioned mounting hole, so that the lifting rod 14 can move freely in the mounting hole.

[0021] The lifting drive device 15 includes a motor 151 and a transmission assembly. The motor 151 is connected to the bottom of the lifting rod 14 through the transmission assembly, so that the lifting rod 14 can be driven to drive the sample stage 13 to move up and down. The structure of the transmission assembly is various; for example, in other embodiments, a rack can be provided on the lifting rod 14, and the motor 151 can drive the rack to move up and down through the gear; or, the lifting rod 14 is restricted from rotating around its own axis, a nut 154 is sleeved on the lifting rod 14, and the axis movement of the nut 154 is restricted, and the motor 151 is used to drive the nut 154 to rotate, and the lifting rod 14 can also move up and down.

[0022] However, in the deposition device 1 provided in this embodiment, the sample stage 13 not only needs to move up and down, but also the angle between the sample stage 13 and the discharge chamber bottom plate 121 (ie, the inclination angle of the sample stage 13) needs to be adjusted; therefore, the transmission assembly provided in this embodiment is different from the traditional structure.

[0023] In this embodiment, the transmission assembly includes a lifting plate 152 and four screw rods 153. Among them, a through hole is provided in the middle of the lifting plate 152, and the lifting rod 14 passes through the through hole in the middle of the lifting plate 152 and is fixedly connected to the lifting plate 152, so that the lifting rod 14 and the lifting plate 152 can move up and down synchronously. The four screw rods 153 are all vertically arranged and are respectively arranged around the lifting plate 152. The screw rod 153 is rotatably connected to the frame, and the bottoms of the four screw rods 153 are connected by belts 155; the upper part of one of the screw rods 153 is transmission-connected to the motor 151; the motor 151 drives the above-mentioned screw rod 153 to rotate, and drives the remaining screw rods 153 to rotate synchronously through the belt 155. A nut 154 is sleeved on the middle part of the screw rod 153, and the nut 154 is fixedly connected to the lifting plate 152. The axial movement of the screw rod 153 is restricted. Therefore, when the screw rod 153 is driven by the motor 151 to rotate, the nut 154 moves axially along the screw rod 153, thereby driving the lifting plate 152 to move up and down.

[0024] Furthermore, the frame also includes a connecting plate 122, which is arranged between the discharge chamber bottom plate 121 and the lifting plate 152, and the upper end of the screw rod 153 is rotatably connected to the connecting plate 122. A sleeve 16 is also arranged between the connecting plate 122 and the discharge chamber bottom plate 121, and the upper and lower ends of the sleeve 16 are respectively fixedly connected to the discharge chamber bottom plate 121 and the connecting plate 122. A through hole is arranged in the middle of the connecting plate 122, and the lifting plate 152 can movably pass through the through hole in the middle of the connecting plate 122; and the connecting plate 122 and the lifting plate 152 are sealed and connected by a retractable bellows. An exhaust hole is arranged on the side wall of the sleeve 16, so as to facilitate the extraction of air in the discharge chamber to form a vacuum discharge environment.

[0025] The upper part of the lifting rod 14 is swingably connected to the frame (directly or indirectly), so that the angle between the axis of the lifting rod 14 and the discharge chamber bottom plate 121 can be adjusted; and when the lifting rod 14 swings, it can drive the sample stage 13 to swing, thereby changing the inclination angle of the sample stage 13.

[0026] In order to facilitate the adjustment of the angle between the sample stage 13 and the bottom plate 121 of the discharge chamber, a pushing assembly is provided at the bottom of the lifting rod 14. By pushing the bottom plate of the lifting rod 14 to move in different directions, the tilt angle of the sample stage 13 can be adjusted. Specifically, a moving block 17 is provided on the lifting plate 152. A through hole is provided in the middle of the moving block 17. The lifting rod 14 passes through the through hole and is fixedly connected to the moving block 17. Pushing blocks 18 are provided around the moving block 17. The pushing blocks 18 are L-shaped structures and are fixedly connected to the moving plate. Pushing screws 181 are provided on the pushing blocks 18. When one of the pushing screws 181 is rotated in a first direction, the pushing screw 181 moves in a direction close to the moving block 17, and can abut against the moving block 17. The pushing screw 181 is further rotated, and the pushing screw 181 can push the moving block 17 to move. When the pushing screw 181 is rotated in a direction opposite to the first direction, the pushing screw 181 moves in a direction away from the moving block 17.

[0027] In addition, the moving block 17 is detachably connected to the lifting plate 152 by bolts. Specifically, the lifting plate 152 is provided with a strip hole, which extends along the radial direction of the lifting shaft; the moving block 17 is provided with a bolt through hole, and the bolt passes through the bolt through hole and the strip hole; when the inclination angle of the lifting rod 14 and the sample stage 13 needs to be adjusted, the bolt is loosened, the moving block 17 is pushed to the preset position, and the bolt is tightened.

[0028] Furthermore, an inner plate 191 is provided in the discharge chamber. The inner plate 191 is a circular plate with a through hole in the middle thereof and an outer edge slidingly matched with the inner wall of the chamber 11. The inner plate 191 is located below the sample stage 13. A swingable bearing is installed in the through hole of the inner plate 191. The lifting rod 14 passes through the inner ring of the bearing to achieve the swing of the lifting rod 14. In other embodiments, the lifting rod 14 can also be connected to the discharge chamber bottom plate 121 or the connecting plate 122 through the swingable bearing.

[0029] In order to adjust the distance between the cavity plate 191 and the sample stage 13, and thus adjust the distribution of the electromagnetic field, an inner bellows 192 and an outer bellows 193 are provided between the cavity plate 191 and the discharge cavity bottom plate 121, wherein the inner bellows 192 is sleeved on the lifting rod 14, and the outer bellows 193 is sleeved on the inner bellows 192. The upper ends of the inner bellows 192 and the outer bellows 193 are both sealedly connected to the cavity plate 191, and the lower ends of the inner bellows 192 and the outer bellows 193 are both sealedly connected to the discharge cavity bottom plate 121, and a receiving space is formed between the inner bellows 192 and the outer bellows 193. An exhaust hole 1211 is provided on the discharge cavity bottom plate 121, and the exhaust hole 1211 is connected to the receiving space for connecting an exhaust pipe. By inflating or exhausting the receiving space, the height of the cavity plate 191 can be adjusted.

[0030] In order to accurately control the lifting height of the cavity plate 191, the radial deformation of the inner bellows 192 and the outer bellows 193 should be minimized; therefore, the inner and outer sides of the inner bellows 192 and the outer bellows 193 are provided with a shaping telescopic tube 194. Embodiment 2:

[0031] This embodiment provides a method for improving coating quality, which uses the microwave plasma chemical vapor deposition device 1 provided in Example 1; the method comprises the following steps: Real-time detection of the temperature at the center position A and the four edge positions of position B, position C, position D and position E of the sample stage 13; When the temperature at the center of the sample stage 13 is higher than the average temperature at the edge of the sample stage 13, the sample stage 13 is raised by a preset distance, so that the sample stage 13 is closer to the plasma ball, thereby making the ellipsoidal plasma ball flatter. Compared with the original plasma ball, the flatter plasma ball has a lower center temperature and a higher edge temperature. After the preset monitoring time is continued, when the temperature at the center of the sample stage 13 is still higher than the average temperature at the edge of the sample stage 13, the height of the cavity plate 191 is lowered. The height of the cavity plate 191 is appropriately lowered to increase the distance between the cavity plate 191 and the sample stage 13, which can also make the ellipsoidal plasma ball flatter. Compared with the original plasma ball, the flatter plasma ball has a lower center temperature and a higher edge temperature.

[0032] Please refer to Figure 4 The edge temperature of the sample stage changes regularly with the distance between the edge of the sample stage and the plasma ball. At the beginning, the edge temperature increases with the increase of the distance. At this time, the corresponding Figure 4 The first half of the temperature curve; after that, the edge temperature decreases as the distance decreases. At this time, the corresponding Figure 4 The second half of the temperature curve. When the microwave plasma chemical vapor deposition equipment is working normally, the distance between the edge of the sample stage and the plasma ball corresponds to Figure 4 The first half of the middle curve.

[0033] When the temperature difference between two relative positions on the edge of the sample stage 13 is greater than a preset difference (e.g., 50°C), the tilt angle of the sample stage 13 is adjusted so that the side with a higher temperature of the sample stage 13 moves toward the plasma ball by a preset distance, and the side with a lower temperature of the sample stage 13 moves away from the plasma ball by a preset distance. By adjusting the tilt angle of the sample stage 13, the distance between the two relative positions and the plasma ball 2 can be changed, so that the temperature distribution of the sample stage 13 is more uniform.

[0034] By adjusting the height and tilt angle of the sample stage 13 in real time, the electromagnetic field distribution is improved, thereby making the coating thickness more uniform and improving the coating quality.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A microwave plasma chemical vapor deposition device, characterized in that: include: A frame, wherein the frame includes a discharge chamber bottom plate; The cavity is a circular cylindrical shape, the bottom of the cavity is connected to the upper part of the discharge cavity bottom plate, and the discharge cavity is enclosed to form a discharge cavity; A sample stage, wherein the sample stage is arranged in the discharge chamber, a lifting rod is arranged at the bottom of the sample stage, a mounting hole is arranged on the bottom plate of the discharge chamber, and the lifting rod can slide through the mounting hole; The lifting drive device comprises a motor and a transmission assembly. The motor is connected to the lifting rod through the transmission assembly and is used to drive the lifting rod to move up and down.

2. The microwave plasma chemical vapor deposition device according to claim 1, characterized in that: The transmission assembly includes a lifting plate and a plurality of screw rods, and the lifting plate is fixedly connected to the lifting rods; The multiple screw rods are all vertically arranged and rotatably connected to the frame, and the axial movement of the multiple screw rods is restricted; a nut is sleeved on each of the screw rods, and the multiple nuts are fixedly connected to the lifting plate; the motor is transmission-connected to the multiple screw rods and can drive the multiple screw rods to rotate synchronously.

3. The microwave plasma chemical vapor deposition device according to claim 2, characterized in that: It also includes a connecting plate, which is arranged between the discharge chamber bottom plate and the lifting plate, and the upper ends of the multiple screw rods are rotatably connected to the connecting plate respectively.

4. The microwave plasma chemical vapor deposition device according to claim 3, characterized in that: A sleeve is provided between the connecting plate and the bottom plate of the discharge chamber, the sleeve is sleeved on the lifting rod, the upper end of the sleeve is fixedly connected to the bottom plate of the discharge chamber, and the lower end is fixedly connected to the connecting plate; the lifting rod can movably pass through the connecting plate, and a sealing member is provided between the lifting rod and the connecting plate; an exhaust hole is provided on the sleeve.

5. The microwave plasma chemical vapor deposition device according to claim 4, characterized in that: The lifting rod is swingably connected to the frame, so that the tilt angle of the sample stage can be adjusted.

6. The microwave plasma chemical vapor deposition device according to claim 5, characterized in that: A moving block is fixedly connected to the lower part of the lifting rod, and the moving block is arranged on the lifting plate; Pushing blocks are arranged around the moving block, and the pushing blocks are fixedly connected to the lifting plate. Each of the pushing blocks is provided with a pushing screw. Rotating the pushing screw in a first direction can make the pushing screw abut against the moving block and push the moving block to move. Rotating the pushing screw in a direction opposite to the first direction can separate the pushing screw from the moving block.

7. A microwave plasma chemical vapor deposition device according to any one of claims 1 to 6, characterized in that: The discharge cavity is also provided with an inner cavity plate, and the inner cavity plate is slidably matched with the inner wall of the cavity; An inner bellows and an outer bellows are provided between the inner plate and the discharge chamber bottom plate, the inner bellows is sleeved on the lifting rod, and the outer bellows is sleeved on the inner bellows; the upper ends of the inner bellows and the outer bellows are both sealedly connected to the inner plate, and the lower ends of the inner bellows and the outer bellows are both sealedly connected to the discharge chamber bottom plate, and a containing space is formed between the inner bellows and the outer bellows; The discharge cavity bottom plate is provided with an exhaust hole, which is communicated with the accommodating space and is used for connecting an exhaust pipe.

8. The microwave plasma chemical vapor deposition equipment according to claim 7, characterized in that: The inner and outer sides of the inner bellows and the outer bellows are both provided with shaped telescopic tubes for reducing the radial deformation of the inner bellows and the outer bellows.

9. A method for improving coating quality, characterized in that: The microwave plasma chemical vapor deposition device according to claim 7 or 8 is used, comprising the following steps: Real-time detection of the temperature at the center and four directions of the edge of the sample stage; When the temperature at the center of the sample stage is higher than the average temperature at the edge of the sample stage, the sample stage is raised by a preset distance. After continuing to monitor for a preset time, when the temperature at the center of the sample stage is still higher than the average temperature at the edge of the sample stage, the height of the cavity plate is lowered. The temperatures of two opposite positions on the edge of the sample stage are the first temperature and the second temperature respectively. When the difference between the first temperature and the second temperature is greater than a preset difference, the inclination angle of the sample stage is adjusted so that the position corresponding to the lower temperature of the first temperature and the second temperature of the sample stage moves a preset distance in the direction away from the plasma ball.

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