Microwave plasma chemical vapor deposition device and heat dissipation ring assembly and vacuum cavity thereof

Abstract

The invention provides a heat dissipation ring assembly of a microwave plasma chemical vapor deposition device, the heat dissipation ring assembly comprises a first annular structure and a second annular structure which have the same central axis, the first annular structure is suitable for being arranged on the upper surface of a base table in a heat conduction mode, and an inner area in the middle of the first annular structure comprises a diamond growth area; the first annular structure is used for placing a wafer and growing diamond on the wafer, the second annular structure is suitable for being arranged on the upper surface of the base table in a heat conduction mode and arranged between the first annular structure and the wafer in a sleeved mode, and the heat conductivity of the second annular structure is lower than that of the first annular structure. And the temperature of the first annular structure is properly reduced, so that the growth rate of the polycrystalline diamond on the surface of the first annular structure is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of vacuum microelectronics, and particularly relates to a microwave plasma chemical vapor deposition device, a heat dissipation ring assembly and a vacuum chamber thereof. Background Art

[0002] A microwave plasma chemical vapor deposition (MPCVD) device generally includes a microwave system, a vacuum system, a gas supply system and a plasma reaction chamber. A self-rotating base is provided in the plasma reaction chamber. Taking the preparation of CVD diamond as an example, the microwave generated by the microwave system enters the plasma reaction chamber, and the gas provided by the gas supply system is excited above the self-rotating base to generate a plasma sphere. The plasma sphere closely adheres to the surface of the film-forming substrate material. By adjusting different reaction gases and the process parameters of the plasma, diamond can be deposited on the substrate material on the surface of the base.

[0003] During the process of growing single-crystal CVD diamond, in order to control the temperature of the single-crystal diamond well, a metal ring is often set. The grown CVD single-crystal diamond is placed in the metal ring, and the temperature of the CVD single-crystal diamond is controlled within an ideal range through the heat dissipation effect of the metal ring, as disclosed in US Patent US6858078B2. When the metal ring makes heat dissipation contact with the side surface of the single-crystal diamond, although the temperature of the side surface of the single-crystal diamond can be improved, a "dead angle" will be formed at the contact area between the outer edge of the diamond and the inner wall of the metal ring after the single-crystal diamond contacts the metal ring. It is very difficult for the plasma to diffuse to this dead angle area, which will affect the growth of the single-crystal diamond in this area. Therefore, in practical applications, the metal ring usually does not make direct contact with the side surface of the single-crystal diamond, but there is a gap. In this case, due to the presence of the metal ring, the heating effect of the plasma on the side surface of the single-crystal diamond will be shielded, and the temperature of the side surface of the single-crystal diamond can also be improved. However, the metal ring is mainly composed of high-temperature resistant materials. In the growth environment of CVD single-crystal diamond, the temperature of the metal ring itself is also relatively high. Therefore, polycrystalline diamond is likely to grow on the upper surface of the metal ring. As the growth time continues to extend, the polycrystalline diamond on the surface of the metal ring will also become thicker and thicker, and finally it is very easy to crack. The broken particles formed after cracking will affect the normal growth of the single-crystal diamond. To reduce the growth rate of the polycrystalline diamond on the surface of the metal ring, it can be achieved by reducing the surface temperature of the metal ring, but this will cause the temperature of the entire metal ring to be very low, resulting in a too low temperature on the side surface of the single-crystal diamond, thus affecting the normal growth of the single-crystal diamond.

[0004] How to appropriately reduce the temperature of the metal ring without significantly reducing the temperature of the side surface of the diamond, so as to reduce the growth rate of the polycrystalline diamond on the surface of the metal ring is a problem to be solved. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide a heat dissipation ring assembly for a microwave plasma chemical vapor deposition device, so as to reduce the growth rate of polycrystalline diamond on the surface of the metal ring without significantly reducing the temperature of the wafer / diamond side surface.

[0006] The present invention provides a heat dissipation ring assembly for a microwave plasma chemical vapor deposition device, characterized in that the heat dissipation ring assembly includes a first annular structure and a second annular structure having the same central axis. The first annular structure is adapted to be thermally conductively disposed on the upper surface of the base. The internal region in the middle of the first annular structure includes a diamond growth region for placing a wafer and growing diamond on the wafer. The second annular structure is adapted to be thermally conductively disposed on the upper surface of the base and sleeved between the first annular structure and the wafer. The thermal conductivity of the second annular structure is lower than that of the first annular structure.

[0007] Preferably, the upper part of the first annular structure includes an annular inner edge portion protruding radially towards the central axis.

[0008] Preferably, the second annular structure is sleeved below the inner edge portion, so that the radial inner surface of the inner edge portion and the radial inner surface of the second annular structure are substantially on the same cylindrical surface.

[0009] Preferably, there is a gap between the second annular structure and the first annular structure to absorb the expansion and contraction caused by temperature changes.

[0010] Preferably, the material of the second annular structure includes silicon dioxide or sapphire.

[0011] Preferably, the material of the first annular structure includes molybdenum metal or tungsten metal.

[0012] Preferably, the first annular structure is a circular ring structure, and the second annular structure is a circular ring structure.

[0013] The present invention also provides a microwave plasma vacuum chamber, characterized in that it includes a base and the heat dissipation ring assembly according to any one of claims 1-7. The base is disposed at the central axis of the vacuum chamber for carrying the wafer and the heat dissipation ring assembly. Above the base, microwave excites reaction gas to form a plasma sphere for diamond growth.

[0014] Preferably, the base includes a cooling system to cool the heat dissipation ring assembly thermally conductively disposed on the surface of the base.

[0015] The present invention also provides a microwave plasma chemical vapor deposition apparatus, which is characterized by comprising a microwave system, a vacuum system, a gas supply system, and a plasma reaction chamber. The plasma reaction chamber includes the microwave plasma vacuum chamber according to any one of the above.

[0016] Here, some terms need to be explained. For example, "radial direction" is defined with reference to the radius direction along the metal ring, and "up" and "down" are defined along the vertical direction.

[0017] These will become clearer in the following description with reference to the accompanying drawings.

[0018] The main beneficial effects of the present invention are as follows:

[0019] 1. For the heat dissipation ring assembly of the microwave plasma chemical vapor deposition apparatus of the present invention, by setting the second annular structure, the temperature of the first annular structure is appropriately reduced without significantly reducing the temperature of the wafer / diamond side surface, thereby reducing the growth rate of polycrystalline diamond on the surface of the first annular structure.

[0020] 2. For the heat dissipation ring assembly of the microwave plasma chemical vapor deposition apparatus of the present invention, the first annular structure can utilize the attraction of the metal to the plasma to guide the plasma to adhere to the periphery of the metal first annular structure, thereby guiding the plasma from near the central axis of the vacuum chamber to the region where the first annular structure is slightly farther from the central axis, so as to form a region with a larger area and a more uniform plasma distribution, improving the deposition quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above content of the present invention and the following specific embodiments will be better understood when read in conjunction with the accompanying drawings. It should be noted that the drawings are only examples of the claimed invention. In the drawings, the same reference numerals represent the same or similar elements.

[0022] Figure 1 is a schematic structural diagram of a microwave plasma vacuum chamber according to an embodiment of the present invention;

[0023] Figure 2 is for the present invention Figure 1 a schematic view in the A-A direction of the microwave plasma vacuum chamber. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following details the detailed features and advantages of the present invention in the specific embodiments. The content is sufficient for any person skilled in the art to understand the technical content of the present invention and implement it accordingly. According to the specification, claims, and drawings disclosed in this specification, those skilled in the art can easily understand the related purposes and advantages of the present invention.

[0025] Figure 1Schematic structural diagram of a microwave plasma vacuum chamber provided according to an embodiment of the present invention; Figure 2 is Figure 1 Cross-sectional schematic view of the microwave plasma vacuum chamber along the A-A direction.

[0026] As Figure 1-2 shown, the heat dissipation ring assembly 110 of the microwave plasma chemical vapor deposition apparatus of this embodiment includes a first annular structure 111 and a second annular structure 112 having the same central axis. The first annular structure 111 is adapted to be thermally conductively disposed on the upper surface of the base 120. The inner region in the middle of the first annular structure 111 is a diamond growth region for placing the wafer 130 and growing diamond thereon. The wafer 130 can be single-crystal or polycrystalline diamond. The first annular structure 111 is used to shield the plasma heating effect on the side of the wafer 130, thereby playing a role in controlling the temperature of diamond growth.

[0027] It can be understood that there are mainly three ways of heat transfer, namely conduction, convection, and radiation. During the preparation of diamond, microwaves excite the reaction gas into a plasma sphere on the upper surface of the base, and diamond is deposited in the diamond growth region on the base surface. Since the plasma above the wafer in the diamond growth region is in a high-temperature state, on the one hand, the plasma heats the wafer surface through thermal radiation, and on the other hand, the lower edge of the plasma sphere contacts the wafer surface, forming thermal contact conduction. The thermal control of the first annular structure on the wafer is achieved by shielding the formation of plasma on the side of the wafer, thereby eliminating the heating of the wafer by the plasma from the side. Therefore, the shielding effect of the plasma heating on the side of the diamond is realized, and the temperature of diamond growth is controlled. In addition, the first annular structure can utilize the attraction of the metal to the plasma to guide the plasma to adhere to the periphery of the metal ring, thereby guiding the plasma from near the central axis of the vacuum chamber to the region where the first annular structure is located slightly farther from the central axis, so as to form a region with a larger area and a more uniform plasma distribution, thereby obtaining higher deposition quality.

[0028] The second annular structure 112 is adapted to be thermally conductively disposed on the upper surface of the base 120 and sleeved between the first annular structure 111 and the wafer 130, and the thermal conductivity of the second annular structure 112 is lower than that of the first annular structure 111.

[0029] It can be understood that by forming the first annular structure and the second annular structure with different materials having different thermal conductivities respectively, the first annular structure and the second annular structure have different surface temperatures, so as to control the heat dissipation of different regions by utilizing the difference in radiative heat dissipation. When the base is cooled, both the first annular structure and the second annular structure are in thermal contact with the surface of the base. In the region with a large thermal conductivity, that is, the region where the first annular structure is located, the cooling effect is good, so the surface temperature is relatively low. In the region with a small thermal conductivity, that is, the region where the second annular structure is located, the cooling effect is worse than that of the first annular structure, and the surface temperature is relatively higher than that of the first annular structure, and the heat dissipation between the second annular structure and the wafer is smaller. When cooling the first annular structure and the second annular structure, since the thermal conductivity coefficient of the second annular structure arranged between the first annular structure and the wafer is small, the heat dissipation is small, and the cooling effect of the first annular structure with a lower temperature can be shielded, so as to reduce the surface temperature of the first annular structure and reduce the growth of polycrystalline diamond on the surface of the first annular structure without affecting the diamond growth in the central region.

[0030] The upper part of the first annular structure 111 includes an annular inner edge part 1111 protruding radially towards the central axis. The second annular structure 112 is sleeved below the inner edge part 1111, so that the radial inner surface of the inner edge part 1111 and the radial inner surface of the second annular structure 112 are basically on the same cylindrical surface.

[0031] It can be understood that the inner edge 1111 of the first annular structure 111 shields the second annular structure 112 from above, which plays a role in preventing the plasma from heating the second annular structure 112, thereby preventing the temperature of the second annular structure from being too high.

[0032] There is a gap between the second annular structure 112 and the first annular structure 111 to absorb the expansion and contraction caused by temperature changes.

[0033] It can be understood that the first annular structure 111 and the second annular structure 112 are made of two different materials. The first annular structure 111 is usually a metal material, while the second annular structure 112 is usually an inorganic material. The thermal expansion coefficients of the two annular structures are significantly different. The service environment of the two annular structures is from room temperature to a high temperature state near 900 degrees Celsius. If the two annular structures are in contact, due to the thermal expansion and contraction effect, it is easy to cause them to crack or deform.

[0034] The material of the second annular structure 112 may include silicon dioxide or sapphire. The material of the first annular structure 111 may include molybdenum or tungsten.

[0035] It should be noted that the first annular structure can be formed of any material with a higher thermal conductivity than the second annular structure, preferably including molybdenum metal or tungsten metal or similar materials; the second annular structure can be formed of any material with a lower thermal conductivity than the first annular structure, preferably including silicon dioxide or sapphire or similar materials.

[0036] The first annular structure 111 is a circular ring structure, and the second annular structure 112 is a circular ring structure.

[0037] It should be noted that the first annular structure and the second annular structure can be any suitable annular (with an annular cross-section) structure, and even can be a polygonal (with a polygonal cross-section) structure. In this embodiment, a circular ring structure (i.e., a cylindrical structure) is adopted.

[0038] As Figure 1 shown, another aspect of this embodiment provides a microwave plasma vacuum chamber. The vacuum chamber 100 is an axisymmetric structure. The vacuum chamber includes a base 120 and the heat dissipation ring assembly 110 in this embodiment. The base 120 is arranged at the central axis of the vacuum chamber 100. The base is used to carry the wafer 130 and the heat dissipation ring assembly 110. Above the base 120, microwave excites the reaction gas to form a plasma sphere 140. The plasma sphere 140 is spherical or ellipsoidal and is used for diamond growth.

[0039] The base 120 includes a cooling system (not shown in the figure) to cool the heat dissipation ring assembly 110 thermally set on the surface of the base 120.

[0040] It can be understood that through the thermal conduction contact between the first annular structure, the second annular structure and the surface of the base, since the base has a cooling system and is cooled, the first annular structure and the second annular structure are cooled. Since the larger the contact area, the more conducive to heat dissipation. To achieve the required heat dissipation effect, the first annular and the second annular need to form sufficient and good contact with the surface of the base.

[0041] It should be noted that the cooling system and its setting can adopt any method known to those skilled in the art. For example, cooling pipes are arranged inside the base, and by introducing a coolant, the cooling function of the base is realized.

[0042] Another aspect of this embodiment provides a microwave plasma chemical vapor deposition device, including a microwave system, a vacuum system, a gas supply system and a plasma reaction chamber. The plasma reaction chamber includes the microwave plasma vacuum chamber 100 of this embodiment.

[0043] It should be noted that the vacuum system is used to achieve a specific vacuum degree, generally in the vacuum range between 2.0 - 30 kPa. There is a circular microwave window above the base. The microwave generated by the microwave system passes through the microwave window from outside and enters the plasma reaction chamber, where the reaction gas provided by the gas supply system is excited above the base to form a plasma sphere, thereby depositing diamond on the surface of the base.

[0044] The terms and expressions used herein are for descriptive purposes only, and the present invention should not be limited to these terms and expressions. The use of these terms and expressions does not mean excluding any equivalent features of the illustration and description (or parts thereof). It should be recognized that various modifications that may exist should also be included within the scope of the claims. Other modifications, variations, and substitutions may also exist. Accordingly, the claims should be regarded as covering all such equivalents.

[0045] Similarly, it should be pointed out that although the present invention has been described with reference to the current specific embodiments, those of ordinary skill in the art should recognize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions can be made without departing from the spirit of the present invention. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the spirit of the present invention, they will fall within the scope of the claims of this application.

Claims

1. A heat dissipation ring assembly of a microwave plasma chemical vapor deposition device, characterized in that, The heat dissipation ring assembly includes a first annular structure and a second annular structure having the same central axis. The first annular structure is adapted to be thermally disposed on the upper surface of the base. The inner region in the middle of the first annular structure includes a diamond growth region for placing a wafer and growing diamond on the wafer. The second annular structure is adapted to be thermally disposed on the upper surface of the base and sleeved between the first annular structure and the wafer. The thermal conductivity of the second annular structure is lower than that of the first annular structure.

2. The heat dissipation ring assembly according to claim 1, wherein The upper part of the first annular structure includes an annular inner edge portion protruding radially towards the central axis.

3. The heat dissipation ring assembly according to claim 2, wherein The second annular structure is sleeved below the inner edge portion, such that the radial inner surface of the inner edge portion and the radial inner surface of the second annular structure are substantially on the same cylindrical surface.

4. The heat dissipation ring assembly according to claim 1, wherein A gap exists between the second annular structure and the first annular structure to absorb expansion and contraction caused by temperature changes.

5. The heat dissipation ring assembly according to claim 1, wherein, The material of the second annular structure includes silicon dioxide or sapphire.

6. The heat dissipation ring assembly according to claim 1, wherein, The material of the first annular structure includes molybdenum metal or tungsten metal.

7. The heat dissipation ring assembly according to claim 1, wherein The first annular structure is a circular ring structure, and the second annular structure is a circular ring structure.

8. A microwave plasma vacuum chamber, characterized in that, It includes a base and the heat dissipation ring assembly according to any one of claims 1-7. The base is disposed at the central axis of the vacuum chamber for carrying the wafer and the heat dissipation ring assembly. Above the base, microwave excites reaction gas to form a plasma sphere for diamond growth.

9. The vacuum chamber according to claim 8, characterized in that, The base includes a cooling system to cool the heat dissipation ring assembly thermally disposed on the surface of the base.

10. A microwave plasma chemical vapor deposition device, characterized in that, It includes a microwave system, a vacuum system, a gas supply system, and a plasma reaction chamber. The plasma reaction chamber includes the microwave plasma vacuum chamber according to any one of claims 8-9.

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