Reaction chamber housing for a microwave plasma chemical vapor deposition apparatus

Abstract

This invention relates to the field of diamond growth using chemical vapor deposition (CVD), specifically to the reaction chamber housing of a microwave plasma chemical vapor deposition (MPCVD) apparatus. This invention addresses the problem of large gaps between the mating surfaces of the cover and base plate in existing reaction chamber housings, which easily lead to microwave leakage. The new reaction chamber housing includes a mating cover and a base plate. The mating surfaces of the base plate that engage with the cover include the upper surface at the edge of the base plate and an annular bevel on the side wall of the base plate. At least two sealing rings are installed at the mating points of the cover and base plate. Some of these sealing rings are located between the upper surface of the base plate and the corresponding mating surface of the cover, while others are located between the annular bevel of the base plate and the corresponding mating surface of the cover. This reduces the number of sealing rings located between the upper surface and the corresponding mating surface of the cover, thereby reducing the gap between the cover and the base plate and significantly lowering the possibility of microwave leakage.

Description

Technical Field

[0001] This utility model relates to the field of diamond growth using chemical vapor deposition, specifically to the reaction chamber shell of a microwave plasma chemical vapor deposition apparatus. Background Technology

[0002] Single-crystal diamond possesses excellent mechanical and chemical properties, showing great promise for applications in ultra-high thermal conductivity materials, high-transmittance optical windows, and semiconductor devices. Microwave plasma chemical vapor deposition (MPCVD) is a commonly used method for preparing high-quality single-crystal diamond. During preparation, the single-crystal diamond is placed on a growth stage within the sealed chamber of a MPCVD apparatus. Microwaves create a strong electric field on the growth stage, and a mixture of hydrogen and methane gas above the stage excites plasma spheres that react with the single-crystal diamond to deposit carbon and grow diamond. Because the growth of high-quality single-crystal diamond requires a special growth environment, the reaction chamber shell of the MPCVD apparatus must meet certain sealing requirements.

[0003] Chinese utility model patent CN216155963U discloses a double-sealed furnace door structure for a microwave plasma cavity. This structure includes a reaction chamber shell, comprising a cover and a base plate that interlock, forming a reaction chamber. The cover has an inlet for hydrogen and methane to enter the reaction chamber, and the base plate has an outlet for vacuuming. The sidewall of the base plate is an annular slope that gradually slopes from bottom to top and from the outside to the inside. The upper surface of the base plate edge and the annular slope on the sidewall serve as mating surfaces for engaging with the cover. The lower edge of the cover has a mating surface that engages with the upper surface of the base plate and the annular slope. To ensure the reaction chamber is sealed, two sealing rings are installed between the upper surface of the base plate and the corresponding mating surface of the cover. A vacuum channel is provided on the base plate to create a negative pressure zone between the sealing rings, thus preventing external impurities from entering the reaction chamber. Because all the sealing rings are sandwiched between the upper surface of the base plate and the corresponding mating surface of the cover, the gap between the cover and the base plate is relatively large. Microwave leakage is likely to occur at the gap. After microwave leakage, the microwave energy distribution in the reaction chamber will be uneven, affecting the stability of the plasma and thus affecting the uniformity and quality of diamond growth. At the same time, microwave leakage will also damage other electronic components of the microwave plasma chemical vapor deposition equipment, increasing maintenance costs. Utility Model Content

[0004] The purpose of this invention is to provide a reaction chamber housing for a microwave plasma chemical vapor deposition (IPD) device, in order to solve the problem that the existing reaction chamber housing has a large gap between the mating surfaces of the cover and the base plate, which easily leads to microwave leakage at the gap.

[0005] The reaction chamber shell of the microwave plasma chemical vapor deposition equipment of this utility model includes a cover and a base plate that interlock. The interlocking surface of the base plate that mates with the cover includes the upper surface at the edge of the base plate and an annular inclined surface at the side wall of the base plate. At least two sealing rings are installed at the interlocking position of the cover and the base plate. Some of the sealing rings are located between the upper surface of the base plate and the corresponding interlocking surface of the cover, and some are located between the annular inclined surface of the base plate and the corresponding interlocking surface of the cover. This allows the sealing rings located on the annular inclined surface to provide uniform support force to the cover in the circumferential direction, ensuring that the cover and the base plate are aligned vertically.

[0006] Furthermore, a microwave shielding ring is installed at the connection point between the cover and the base plate.

[0007] Furthermore, the microwave shielding ring is an elastic shielding ring, located between the upper surface of the base plate and the corresponding cover fastening surface. The deformation of the microwave shielding ring in the vertical direction is less than the deformation of the sealing ring, so as to ensure the sealing performance of the sealing ring.

[0008] Furthermore, the microwave shielding ring is a circular helical spring.

[0009] Furthermore, the microwave shielding ring is located inside the sealing ring to shield and block microwaves at the front end of the leakage gap.

[0010] Furthermore, at the mating position on the upper surface of the cover and the bottom plate at the edge, at least one of the cover and the bottom plate is provided with a raised surface facing the other, and the microwave shielding ring is located outside the raised surface, so that after the cover and the bottom plate are fastened together, a smaller fastening gap is formed on the inner side of the microwave shielding ring.

[0011] Furthermore, the upper surface of the bottom plate edge position that mates with the cover is a stepped surface that decreases one level from the inside to the outside, with the microwave shielding ring located on the lower upper surface and the higher upper surface forming the convex surface.

[0012] Furthermore, a sealing ring mounting groove for mounting the sealing ring at the annular inclined surface of the base plate is provided on the base plate, and a vacuum passage on the base plate for forming a negative pressure area between the sealing rings is also connected to the interlayer between the sealing ring mounting groove and the sealing ring placed therein.

[0013] Furthermore, the outline shape of the sealing ring mounting groove on the annular inclined surface is triangular, and the vacuum passage extends to the bottom of the triangular sealing ring mounting groove.

[0014] Furthermore, the vacuum passage is zigzag-shaped, including an end passage that extends vertically and vertically through the interlayer between the sealing rings, a central horizontal passage that extends radially from the outside to the inside, and a first passage that connects the central horizontal passage and the lower surface of the base plate. The end passage is located radially outside the first passage and extends in a zigzag shape to avoid other components installed at the edge of the base plate.

[0015] This invention proposes an improved technical solution to address the aforementioned technical problems. A portion of the sealing ring installed at the engagement point between the base plate and the cover is positioned between the upper surface of the base plate and the corresponding engagement surface of the cover, while the other portion is installed between the annular inclined surface of the base plate and the corresponding engagement surface of the cover to ensure coaxial assembly of the cover and the base plate. This reduces the number of sealing rings located between the upper surface of the base plate and the corresponding engagement surface of the cover, thus reducing the upward force exerted by the sealing rings on the cover. This reduces the gap between the cover and the base plate, significantly lowering the possibility of microwave leakage, ensuring the stability of the plasma within the reaction chamber, and consequently guaranteeing the uniformity and quality of diamond growth. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the reaction chamber shell and its internal components of the microwave plasma chemical vapor deposition equipment of this utility model.

[0017] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0018] Figure 3 This is a schematic diagram of a microwave plasma chemical vapor deposition (PVDC) device.

[0019] In the diagram: 1. Cover; 11. Inflation port; 12. Shielding ring mounting groove; 2. Base plate; 21. Gas duct interface; 22. Upper surface; 23. Annular inclined surface; 24. Vacuum duct; 25. First sealing ring mounting groove; 26. Second sealing ring mounting groove; 27. Ejection port; 3. Sealing ring; 4. Microwave shielding ring; 5. Growth substrate; 6. Plasma sphere; 7. Reaction chamber; 8. First interlayer; 9. Second interlayer; V1. Mixing valve; V2. Baffle valve; V3. Fine extraction valve; V4. Proportional valve; V5. Venting valve; V6. Inflation valve; Q1. First vacuum gauge; Q2. Second vacuum gauge; M1. Vacuum pump. Detailed Implementation

[0020] This invention proposes an improved technical solution to address the aforementioned technical problems. The core concept of this invention is to install a portion of the sealing ring at the engagement point between the base plate and the cover between the upper surface of the base plate and the corresponding engagement surface of the cover, and another portion between the annular inclined surface of the base plate and the corresponding engagement surface of the cover to ensure coaxial assembly of the cover and the base plate. This reduces the number of sealing rings between the upper surface of the base plate and the corresponding engagement surface of the cover, thus reducing the upward force exerted by the sealing rings on the cover. This reduces the gap between the cover and the base plate, significantly lowering the possibility of microwave leakage, ensuring the stability of the plasma within the reaction chamber, and consequently ensuring the uniformity and quality of diamond growth.

[0021] A specific embodiment of the reaction chamber shell of the microwave plasma chemical vapor deposition equipment of this utility model is as follows:

[0022] The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus includes, as follows: Figure 1 The cover 1 and base plate 2, which interlock, form a reaction chamber 7. The cover 1 has an inlet 11 for connecting to a gas delivery system to allow mixed gas to enter the reaction chamber 7. The base plate 2 has an outlet 27 for connecting to a vacuum system. During operation, the internal pressure of the reaction chamber 7 must be stably controlled at 15-20 kPa. The mating surfaces of the base plate 2 and the cover 1 include the upper surface 22 at the edge of the base plate 2 and the annular inclined surface 23 on the side wall of the base plate 2. Two sealing rings 3 are installed at the mating points of the cover 1 and the base plate 2. Figure 2 As shown, one of the two sealing rings 3 is located between the upper surface 22 and the corresponding mating surface of the cover 1, and the other is located between the annular inclined surface 23 and the corresponding mating surface of the cover 1. This allows the sealing ring 3 located on the annular inclined surface 23 to provide uniform support force to the cover 1 in the circumferential direction, ensuring the vertical alignment of the cover 1 and the base plate 2. This reduces the number of sealing rings 3 located between the upper surface 22 and the corresponding mating surface of the cover 1, thus reducing the upward force exerted by the sealing rings 3 on the cover 1. This reduces the gap between the cover 1 and the base plate 2, significantly reducing the possibility of microwave leakage, ensuring the stability of the plasma in the reaction chamber 7, and consequently ensuring the uniformity and quality of diamond growth. However, when the gap between the cover 1 and the base plate 2 is large in the vertical direction, it is difficult to ensure alignment in the vertical mating direction, easily leading to a situation where one side has a larger gap and the other side has a smaller gap in the horizontal direction. In this embodiment, the gap between the cover 1 and the base plate 2 in the vertical direction is small. At this time, the gap between the annular inclined surface 23 and the corresponding fastening surface of the cover 1 will also be reduced. Meanwhile, the sealing ring at the annular inclined surface 23 can support the cover 1 in the circumferential direction. The circumferential force on the cover 1 is uniform, ensuring the coaxial assembly between the base plate 2 and the cover 1.

[0023] A microwave shielding ring 4 is also installed between the upper surface 22 of the base plate 2 and the corresponding mating surface of the cover 1. For example... Figure 2As shown, the cover 1 is provided with a shielding ring mounting groove 12 for installing the microwave shielding ring 4, and the shielding ring mounting groove 12 is located inside the mounting position of the sealing ring 3 to shield and block microwaves at the front end of the leakage gap. The presence of the microwave shielding ring 4 is more conducive to avoiding microwave leakage, ensuring the stability of the plasma in the reaction chamber 7, and thus ensuring the uniformity and quality of diamond growth. The microwave shielding ring 4 is a circular helical spring, and the deformation of the microwave shielding ring 4 in the vertical direction is less than the deformation of the sealing ring 3. Thus, when the cover 1 and the base plate 2 are fastened together, the sealing ring 3 is deformed first, and then the microwave shielding ring 4 is deformed again, so that its upper and lower ends are respectively pressed against the cover 1 and the base plate 2, ensuring the reliability of the installation of the microwave shielding ring 4 while also ensuring the sealing performance between the base plate 2 and the cover 1. The upper surface of the base plate 2, which mates with the cover 1, is a stepped surface that decreases one level from the inside out. The microwave shielding ring is located on the lower upper surface, while the higher upper surface forms a raised surface facing the corresponding cover mating surface. This creates a smaller mating gap inside the microwave shielding ring 4 after the cover 1 and base plate 2 are mated. The smaller mating gap significantly reduces the possibility of microwave leakage, ensuring the stability of the plasma within the reaction chamber 7.

[0024] like Figure 2 As shown, after the two sealing rings 3 are installed, the gap between them, the cover 1, and the base plate 2 forms an annular first interlayer 8. A vacuum channel 24 is provided on the base plate 2, connecting the first interlayer 8 to the outside. The vacuum channel 24 is connected to a vacuum system to create a negative pressure chamber in the first interlayer 8. Thus, the first interlayer 8 maintains a negative pressure state both inside and outside the reaction chamber 7, protecting the reaction chamber 7 from the intrusion of external impurity gases. A sealing ring mounting groove for installing the sealing rings 3 is provided on the base plate 2, such as... Figure 2 As shown, the chamber includes a first sealing ring mounting groove 25 located on the upper surface 22 and a second sealing ring mounting groove 26 located on the annular inclined surface 23. The outline of the second sealing ring mounting groove 26 is triangular. An annular second interlayer 9 is formed between the second sealing ring mounting groove 26 and the sealing ring 3 installed therein at the bottom of the groove. The vacuum channel 24 on the bottom plate 2, which is used to form a negative pressure area between the sealing rings 3, is also connected to the second interlayer 9. In this way, negative pressure can be drawn at the second interlayer 9, further preventing external air impurities from entering the reaction chamber 7. The vacuum channel 24 is zigzag-shaped and includes an end air channel that connects to the first interlayer 8 between the sealing rings 3 and extends vertically, a middle horizontal air channel that starts from the bottom of the triangular second sealing ring mounting groove 26 and extends radially from the outside to the inside, and a first section air channel that connects the middle horizontal air channel and the lower surface of the bottom plate. The end air channel is located radially outside the first section air channel and extends in a zigzag shape to avoid other components installed at the edge of the bottom plate 2.

[0025] like Figure 3As shown, during use, diamond is placed on the growth stage 5 inside the reaction chamber housing of the microwave plasma chemical vapor deposition equipment. The vacuum system draws a vacuum through vacuum pump M1. When the vacuum system is connected to the evacuation port 27, a first vacuum gauge Q1 is installed on its pipeline to monitor the internal gas pressure of the reaction chamber 7. A baffle valve V2, a fine evacuation valve V3, and a proportional valve V4 are also installed. The internal gas pressure of the reaction chamber 7 is stably controlled at 15-20 kPa through the baffle valve V2, fine evacuation valve V3, and proportional valve V4. Subsequently, the mixing valve V1 on the gas delivery system is opened to allow a mixed gas (hydrogen and methane) to be introduced into the reaction chamber 7. The mixed gas is excited by microwave energy above the growth stage 5 to form plasma, which participates in the synthesis of diamond. A second vacuum gauge Q2 is installed on the pipeline connecting the vacuum system to the gas channel interface 21 to detect the internal gas pressure of the interlayer. Simultaneously with the introduction of the mixed gas into the reaction chamber 7, the vacuum system evacuates the first interlayer 8 and the second interlayer 9, ensuring that the gas pressure in both interlayer 8 and 9 is stably controlled below 1 kPa so that the interlayers are under negative pressure both inside and outside the reaction chamber 7, and that the interlayers are under continuous vacuum. This ensures the airtightness of the reaction chamber 7. After synthesis, opening the vent valve V5 breaks the vacuum in the reaction chamber.

[0026] This utility model also provides other embodiments regarding the microwave shielding ring. In one embodiment, the microwave shielding ring can also be flush with the sealing ring, so that when the upper and lower ends of the sealing ring are respectively pressed against the cover and the bottom plate, the upper and lower ends of the microwave shielding ring are also pressed against the cover and the bottom plate respectively.

[0027] This utility model also provides other embodiments regarding the microwave shielding ring. In one embodiment, the microwave shielding ring can be an elastic conductive foam ring made by foaming technology; in another embodiment, the microwave shielding ring can also be a non-elastic metal shielding ring. When it is fastened in place, the upper and lower ends of the metal shielding ring should just abut against the cover and the base plate to ensure its shielding effect.

[0028] Regarding the placement of the microwave shielding ring, this utility model also provides other embodiments. In another embodiment, the microwave shielding ring can be placed between the upper surface of the base plate and the corresponding cover fastening surface, at the outer position of the shielding ring. In another embodiment, the microwave shielding ring can also be placed between the annular inclined surface and the corresponding cover fastening surface. Of course, in another embodiment, the shielding ring mounting groove can also be provided on the base plate, and the shielding ring can be mounted on the base plate.

[0029] Regarding the arrangement of the vacuum channels, this utility model also provides other embodiments. In another embodiment, in order to avoid other components, the vacuum channels can also be arranged in an oblique line, as long as they can extend to the second interlayer so that the second interlayer is in a negative pressure state.

[0030] Regarding the shape of the second sealing ring mounting groove at the annular inclined surface, this utility model also provides another embodiment. In another embodiment, the outline shape of the second sealing ring mounting groove can be U-shaped. After the sealing ring is installed in this U-shaped mounting groove, two interlayers will be formed at the bottom of the groove. At this time, the vacuum channel on the bottom plate used to form a negative pressure area between the sealing rings can also be connected to the interlayer closer to the inner side, so as to prevent external air impurities from entering the reaction chamber.

[0031] Regarding the placement of the sealing ring, this utility model also provides other embodiments. In another embodiment, the sealing ring mounting groove is provided on the cover, but in this case, an anti-detachment closing opening needs to be provided at the opening of the sealing ring mounting groove on the cover.

[0032] In another specific embodiment of the reaction chamber housing of the microwave plasma chemical vapor deposition equipment of this utility model, the difference from the above embodiment is that: three or more sealing rings are provided on the plate at the position where it is fastened to the cover. Some of the sealing rings are located between the upper surface and the corresponding cover fastening surface, and some are located between the annular inclined surface and the corresponding cover fastening surface. In this way, compared with the method of placing all the sealing rings between the upper surface and the corresponding cover fastening surface, this embodiment can reduce the gap between the cover and the bottom plate, and significantly reduce the possibility of microwave leakage.

[0033] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. The patent protection scope of the present utility model shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present utility model shall also be included within the protection scope of the present utility model.

Claims

1. A reaction chamber shell for a microwave plasma chemical vapor deposition apparatus, comprising a cover and a base plate that interlock, wherein the interlocking surface of the base plate that mates with the cover includes an upper surface at the edge of the base plate and an annular inclined surface at the side wall of the base plate, and at least two sealing rings are installed at the interlocking positions of the cover and the base plate, characterized in that: Some of the sealing rings are located between the upper surface of the base plate and the corresponding mating surface of the cover, while others are located between the annular inclined surface of the base plate and the corresponding mating surface of the cover. This allows the sealing rings located on the annular inclined surface to provide uniform support to the cover in the circumferential direction, ensuring that the cover and the base plate are aligned vertically.

2. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to claim 1, characterized in that: A microwave shielding ring is also installed at the snap-fit ​​point between the cover and the base plate.

3. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to claim 2, characterized in that: The microwave shielding ring is an elastic shielding ring, located between the upper surface of the base plate and the corresponding cover fastening surface. The deformation of the microwave shielding ring in the vertical direction is less than the deformation of the sealing ring, so as to ensure the sealing performance of the sealing ring.

4. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to claim 3, characterized in that: The microwave shielding ring is a circular helical spring.

5. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to any one of claims 2-4, characterized in that: The microwave shielding ring is located inside the sealing ring to shield and block microwaves at the front end of the leakage gap.

6. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to claim 5, characterized in that: At the mating position on the upper surface of the cover and the bottom plate at the edge, at least one of the cover and the bottom plate is provided with a raised surface facing the other, and the microwave shielding ring is located outside the raised surface so that after the cover and the bottom plate are fastened together, a smaller fastening gap is formed on the inner side of the microwave shielding ring.

7. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to claim 6, characterized in that: The upper surface of the bottom plate edge position that mates with the cover is a stepped surface that decreases one level from the inside to the outside. The microwave shielding ring is located on the lower upper surface, and the higher upper surface constitutes the convex surface.

8. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to any one of claims 1-4, characterized in that: A sealing ring mounting groove for mounting the sealing ring at the annular inclined surface of the base plate is provided on the base plate. A vacuum passage on the base plate for forming a negative pressure area between the sealing rings is also connected to the interlayer between the sealing ring mounting groove and the sealing ring placed therein.

9. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to claim 8, characterized in that: The outline of the sealing ring mounting groove on the annular inclined surface is triangular, and the vacuum passage extends to the bottom of the triangular sealing ring mounting groove.

10. The reaction chamber housing of the microwave plasma chemical vapor deposition apparatus according to claim 8, characterized in that: The vacuum passage is zigzag-shaped, including an end passage that extends vertically and vertically through the interlayer between the sealing rings, a middle horizontal passage that extends radially from the outside to the inside, and a first passage that connects the middle horizontal passage and the lower surface of the base plate. The end passage is located radially outside the first passage and extends in a zigzag shape to avoid other components installed at the edge of the base plate.

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