MPCVD equipment

Abstract

The invention discloses MPCVD equipment. The MPCVD equipment comprises a rack; the deposition chamber is provided with an upper chamber opening and a lower chamber opening, and the lower chamber opening is provided with a chamber sealing lower cover with a lifting hole; the resonant cavity is functionally communicated with the deposition chamber through a quartz window; the microwave generation and transmission device enables microwaves to penetrate through the quartz window to ionize the reaction gas; a vacuumizing device; the gas control device is connected to the deposition chamber so as to provide reaction gas for the deposition chamber; and the lifting device is configured on the rack and drives the growth base table to lift through a part intervening into the deposition chamber, so that the deposition surface of the substrate on the growth base table is always positioned at a preset height of the deposition chamber in the growth process. According to the MPCVD equipment disclosed by the invention, the working environment of the MPCVD can be stably controlled.

Description

Technical Field

[0001] The present invention relates to an MPCVD device, wherein MPCVD is the abbreviation of Microwave Plasma Chemical Vapor Deposition, i.e. microwave plasma chemical vapor deposition. Background Art

[0002] It should be known that, for example, artificial diamond (hereinafter referred to as diamond) is an industrial material that can be prepared by MPCVD equipment. Diamond is an ultra-wide bandgap semiconductor that combines excellent electrical, optical, mechanical, thermal and chemical properties. It is known as the "ultimate semiconductor material" and the "ultimate room temperature quantum material". Diamond has many excellent physical and chemical properties, such as high hardness, high thermal conductivity, high chemical stability, high optical transmittance, extremely wide bandgap width, negative electron affinity, high insulation and good biocompatibility. These unique physical and chemical properties combined together allow diamond to be applied in many fields, and can be widely used in key parts in cutting-edge fields such as 5G communications, semiconductors, high-end equipment, aerospace, national defense and military industry, which also makes diamond one of the most promising new functional materials in recent decades.

[0003] At present, MPCVD has become the optimal chemical vapor deposition method for synthetic diamonds due to its high energy density, no internal electrode pollution in the reaction chamber, a wide variety of process gases, continuous and stable controllable microwave power, stable and controllable growth temperature field, high purity of grown diamond crystals, and low defect density. It can deposit tool-grade diamond films, heat sink-grade diamond films, optical-grade diamond films, or device-grade diamond films at a rate of microns per hour. It can also be used for graphene deposition, material surface treatment, and low-temperature oxide growth. MPCVD technology can also be used to cultivate diamonds, and its price is only about a quarter of that of natural diamonds. MPCVD technology has become a hot topic of research at home and abroad due to its unique advantages and broad application prospects.

[0004] MPCVD uses microwave energy to excite gas molecules containing diamond precursors, mainly hydrogen and methane (reaction gas), to produce high-concentration plasma, which cracks methane and hydrogen into free carbon groups and various ions at a temperature of several thousand degrees. The free carbon active groups are then adsorbed on the surface of the growth substrate to form a deposition of carbon elements. In this process, plasma not only realizes the preparation of raw materials for diamond growth, but also provides a driving force for the stable transmission of free carbon groups.

[0005] The current mainstream MPCVD equipment mainly has two chamber structures, namely cylindrical cavity structure and dish-shaped cavity structure. Among them, the cylindrical cavity structure microwave enters the reaction chamber by feeding from the top of the cavity to couple to form a plasma sphere, and the dish-shaped cavity structure microwave enters the reaction chamber by feeding from the bottom of the cavity to couple to form a plasma sphere. Mainly limited by the shape and structure of the chamber, for example, the microwave energy density, microwave discharge area, and microwave plasma stability are poor and easy to jump, and it is impossible to prepare larger sizes such as diamond crystals with high quality, and therefore cannot meet the user's application needs for high-quality large-size diamond crystals. Summary of the invention

[0006] The object of the present invention is to provide an MPCVD device capable of stably controlling the MPCVD working environment.

[0007] According to an embodiment of the present invention, there is provided an MPCVD device, comprising: frame; The deposition chamber is vertically arranged on the frame and has an upper chamber opening and a lower chamber opening, wherein the upper chamber opening is provided with a chamber sealing upper cover, and the lower chamber opening is provided with a chamber sealing lower cover with a lifting hole; a quartz window is provided at a predetermined position on the side wall of the deposition chamber; and a growth base is provided in the deposition chamber; The resonant cavity is arranged outside the deposition chamber and is functionally connected to the deposition chamber through a quartz window; A microwave generating and transmitting device is connected to the resonant cavity through a microwave conduit so that the microwave can pass through the quartz window to ionize the reaction gas; A vacuum pumping device is inserted into the deposition chamber to vacuum the deposition chamber; a gas control device connected to the deposition chamber to provide reaction gas to the deposition chamber; The lifting device is arranged on the frame, and drives the growth base to rise and fall by intervening in the deposition chamber, so that the deposition surface of the substrate on the growth base is always located at a predetermined height of the deposition chamber during the growth process.

[0008] Optionally, the resonant cavity has a cover nested outside the deposition chamber, and a given distance is left between the cover and the deposition chamber; The enclosure is provided with microwave feeding slots in the middle of the vertical direction; Correspondingly, the deposition chamber has a quartz tube which is surrounded by a chamber sealing upper cover and a chamber sealing lower cover to form a furnace cavity, and the microwave feeding gap determines the feeding range and further determines the quartz window of the quartz tube; The surface of the growth base for supporting the substrate is located in the quartz tube section determined by the microwave feeding gap.

[0009] Optionally, the microwave feeding slots include transverse slots and vertical slots, wherein the transverse slots are evenly distributed vertically.

[0010] Optionally, there are two groups of microwave feeding slots, and one group is arranged on two opposite sides of the enclosure, one of which is the side where the microwave guide tube is located.

[0011] Optionally, the width of the transverse slot in the microwave feeding slot group is the same as that of the vertical slot, and the vertical slot passes through the transverse slot in the vertical center.

[0012] Optionally, the angle between the horizontal gap and the vertical gap is 60° to 90°; The length of the vertical gap is also the same as the length of the horizontal gap; The aspect ratio of the transverse slot is 20:1~15:1, and the length of the microwave feeding slot is 45mm~55mm.

[0013] Optionally, heat dissipation holes are provided on the upper and lower parts of the enclosure.

[0014] Optionally, the chamber sealing upper cover has an upper center hole, and a metal bottom plate of a biasing device is mounted on the chamber sealing upper cover; Correspondingly, a bias device is provided outside the chamber sealing upper cover to apply a positive electric field to the microwave plasma through the metal bottom plate of the bias device.

[0015] Optionally, the biasing device further comprises: The fourth guide assembly is disposed on the chamber sealing cover to provide guidance in the up-down direction; A fourth slide seat is guided by the fourth guide assembly, the fourth slide seat is connected to the chamber sealing upper cover by a second sealing spring sealing tube, and a metal cylinder is fixedly connected to the center, one end of the metal cylinder is inserted into the deposition chamber through the upper center hole, and the other end of the metal cylinder protrudes from the upper end of the fourth slide seat or is connected to a probe electrode; A pair of third guide rods are arranged in parallel at the upper end of the fourth slide, and the corresponding two third guide rods are interconnected by a crossbeam; A clamping rod is installed on the cross beam so as to press down the fourth slide seat through adjustment of the clamping rod after the fourth slide seat is adjusted into place.

[0016] Optionally, the lifting device comprises: A first lifting device, mounted on the frame and having a first lifting plate; The second lifting device includes a pedestal, a chamber base, a chamber base sealing disk and a driving device for driving the chamber base sealing disk, wherein the pedestal is fixed on the frame to support the sealed chamber, and the pedestal is configured with a sealing stop; the chamber base sealing disk and the chamber base constituting the chamber sealing lower cover are connected by a first sealing spring sealing tube; the chamber base and the first lifting disk are supported and connected by a second guide rod, and are opened and closed by the driving of the first lifting device with the sealing stop; the chamber base sealing disk is used to support the growth base, and the chamber base sealing disk controls the growth base to rise and fall under the lifting drive of the driving device.

[0017] In an embodiment of the present invention, the provided MPCVD equipment configures the deposition chamber as a vertical chamber, and the resonant cavity is functionally connected through a predetermined quartz window. During the predetermined surface deposition process of the substrate, the lifting device supporting the growth base adjusts the height according to the growth condition of the substrate, so that the surface of the substrate currently used to grow the crystal is at a suitable height in the deposition chamber, and the working environment of the MPCVD, specifically the growth environment of the deposition layer on the substrate, can be stably controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the main structure of MPCVD in one embodiment.

[0019] Figure 2 for Figure 1 Enlarged view of part I.

[0020] Figure 3 This is a picture of a diamond single crystal material sample in one embodiment.

[0021] Figure 4 This is a Raman spectrum of the surface of a diamond sample prepared in one embodiment.

[0022] In the figure: 1. frame, 2. first guide rod, 3. secondary lifting motor, 4. first lifting plate, 5. second lifting screw nut screw pair, 6. second screw nut frame, 7. chamber base sealing plate, 8. first sealing spring sealing tube, 9. chamber base, 10. air cooling device, 11. microwave surround resonant metal cavity, 12. growth base, 13. quartz tube, 14. chamber sealing cover, 15. sealing ring, 16. second sealing spring sealing tube, 17. second connecting flange, 18. molybdenum metal cylinder, 19. Probe electrode, 20. Screw, 21. Nut, 22. Handwheel, 23. First limit plate, 24. Third guide rod, 25. Second limit plate, 26. Fourth guide rod, 27. Fourth slide, 28. Base plate, 29. Annular cover, 30. Base, 31. First lifting motor, 32. Second guide sleeve, 33. Second guide rod, 34. First guide sleeve, 35. First slide, 36. First lifting mechanism, 37 Microwave feeding gap, 38. Metal enclosure, 39. Heat dissipation pores, 40. Microwave source. DETAILED DESCRIPTION

[0023] In view of the fact that the MPCVD equipment is already a very mature equipment, its inherent configuration parts usually include a frame 1, a deposition chamber, a resonant cavity, microwave generation and traditional devices, a vacuum device, a gas control device, a substrate heating and temperature control system, a cooling system, and a monitoring and control system. This is the general structure of the MPCVD. In the embodiments of the present invention, the focus is on explaining the improved parts, and its common configuration and the parts that are not related to the improved parts of the embodiments of the present invention will not be described in detail. Those skilled in the art can understand based on the general structure of the MPCVD equipment and can confirm its specific configuration without creative work.

[0024] To help people have an overall understanding of the present invention, the main invention points involved in the embodiments of the present invention are briefly described below. The first invention point is that the position of the growth base 12 included in the deposition chamber in the up and down directions in the deposition chamber can be adjusted to adapt to, for example, the growth rate of the diamond crystal, so that the surface being deposited, for example, diamond, is at approximately the same height in the deposition chamber.

[0025] The second inventive point is to provide a bias device at the upper end of the deposition chamber to further optimize the state of the plasma by constructing a bias electric field.

[0026] The third invention point is that by setting a microwave feeding gap at the resonant cavity, a working environment with high energy density, a relatively larger discharge area, and a plasma with better uniformity and stability can be obtained under the same microwave power.

[0027] The fourth invention point is that by rationally configuring the deposition chamber and the resonant cavity, the microwave feeding and the temperature field are coordinated to obtain a better growth environment.

[0028] The basic structure of the MPCVD equipment is described below, and then the parts related to the above-mentioned invention points are explained in detail.

[0029] First, regarding the frame 1, in an embodiment of the present invention, the deposition chamber adopts a vertical structure, and the frame 1 correspondingly adopts a frame that conforms to the deposition chamber with a vertical structure. In view of the fact that the current deposition chamber is mainly a vertical structure and the horizontal structure is relatively rare, in other words, for technicians in this field, the vertical structure is a common structure and will not be repeated here.

[0030] In addition, regarding the frame 1, it is generally a frame structure of welded steel sections, which may have casters or not. Since this part of the configuration is irrelevant to the inventive point of the present invention, it will not be described here.

[0031] Generally speaking, the deposition chamber is generally fixedly disposed at the upper end of the frame 1. In some embodiments, in order to ensure the stability of the deposition chamber, additional support may be provided between the middle of the deposition chamber and the frame 1. In some other embodiments, the upper portion of the deposition chamber may also be supported or connected to the frame 1.

[0032] Different from other types of CVD equipment, MPCVD equipment is a CVD equipment that absolutely avoids direct involvement of electrodes in the reaction area of ​​the deposition chamber. The purpose of this design is to effectively avoid electrode contamination of traditional CVD equipment and ensure the high purity of the deposited material.

[0033] The deposition chamber usually includes a furnace body, which can be, for example, a graphite furnace body or a quartz furnace body, wherein the quartz furnace body itself is a furnace body that does not have an isolation effect on microwaves, and its periphery can facilitate the coupling of microwaves with the reaction gas in the furnace body. If a furnace body made of an opaque material, such as a graphite furnace body, is used, it is necessary to construct a quartz window, for example, by inlaying, so that microwaves can couple with the reaction gas in the furnace body through the quartz window. This method of achieving coupling is often referred to as functional connectivity in the art. This functional connectivity and physical connectivity are two completely different connectivity methods. Please note that functional connectivity does not lead to physical connectivity, that is, for example, the furnace body mainly constructed with a quartz tube 13 and the resonant cavity are isolated, so that when the furnace body is evacuated, the resonant cavity will not be evacuated at the same time.

[0034] For example, the quartz tube 13 is a circular tube structure as a whole, and has an upper opening and a lower opening based on the aforementioned vertical arrangement, corresponding to the upper chamber opening and the lower chamber opening of the deposition chamber, and a relatively tight deposition chamber is formed based on the sealing of the two chamber openings.

[0035] Correspondingly, the upper chamber opening is equipped with a chamber sealing upper cover 14, and the lower chamber opening is equipped with a chamber sealing lower cover, such as Figure 1 The chamber base 9 shown in FIG. Figure 1In the illustrated structure, the through hole portion of the chamber base 9 is relatively large, so as to facilitate the connection between the growth base 12 and the lifting device that drives the growth base 12 to rise and fall.

[0036] Obviously, the growth platform 12 is located in the deposition chamber, and in some embodiments, the substrate can be taken in and out from the upper chamber port.

[0037] Regarding the resonant cavity, it is usually arranged outside the deposition chamber and functionally connected to the deposition chamber through a quartz window. The resonant cavity is generally a metal sealed cavity, such as Figure 2 The metal enclosure 38 shown in the figure and the resonance cavity constructed by the annular cover shell 29, the annular cover shell 29 is also made of metal material, preferably aluminum alloy material.

[0038] Figure 1 In the figure, two roughly tubular parts are shown on the left and right sides of the quartz tube 13, forming a microwave surround resonant metal cavity 11, which is contained in the resonant cavity, wherein the part located on the right side includes a microwave guide tube and a microwave generating device.

[0039] It should be known that the microwave generating device mainly includes a magnetron, and the way in which it generates microwaves does not belong to the improvement of the present invention, but is a basic application of the microwave generating device. Its access method is also its basic access method, such as directional access through the aforementioned microwave guide tube (generally referred to as a waveguide) to avoid energy loss, which belongs to the basic configuration in this field.

[0040] At the same time, it should be known that the microwave generating device often has impedance matching and tuning functions. According to the on-site conditions, impedance matching and tuning can ensure that the microwave capacity is coupled to the reaction gas in the deposition chamber to the greatest extent.

[0041] It should be noted that the resonant cavity and the microwave generating and transmitting device are often an integral component. In the embodiments of the present invention, the resonant cavity is described independently only to fully illustrate other inventive points of the embodiments of the present invention.

[0042] It should be further explained that, in conventional MPCVD, microwaves are often output from a magnetron with the aid of a coupling ring or an antenna, whereas in the embodiments of the present invention, on this basis, a metal enclosure 38 with a specific structure constructed in the resonant cavity outputs microwaves in a directional manner, wherein the specific structure on the metal enclosure 38 is that a microwave feeding slot 37 is provided on the side of the metal enclosure 38, and the microwave feeding is more accurately controlled by rationally arranging the shape and distribution range of the microwave feeding slot 37, thereby more effectively controlling the area suitable for crystal growth, making the microwave energy more concentrated, and facilitating the control of the crystal growth quality.

[0043] Accordingly, microwaves are transmitted through the quartz window to ionize the reaction gas, thereby generating plasma, through direct and directional transmission of microwave guide tubes. The main reactions are common knowledge in the art. First, hydrogen and methane molecules are polarized, and some reaction gas molecules are accelerated to a high energy state, thereby ionizing. The free electrons generated by ionization are further accelerated in the microwave field, causing avalanche ionization, and gradually turning the reaction gas into plasma.

[0044] It should be known that the continuous input of microwave energy allows the plasma to maintain a stable plasma state, and then the active groups in the plasma participate in the deposition reaction of, for example, a diamond film (substrate), so that C is deposited on the diamond film.

[0045] As a necessary configuration, it is necessary to equip the deposition chamber with a vacuum pump. Specifically, before the reaction gas is injected into the deposition chamber, the deposition chamber needs to be evacuated. When evacuating, the basic vacuum degree in the deposition chamber needs to reach 10⁻ 5 ~ 10⁻ 6 Torr is used to remove impurities, and the working vacuum is usually controlled at 10⁻² ~ 10⁻³ Torr to ensure plasma stability and reaction efficiency.

[0046] Another point to note is that different vacuum levels have different effects on deposition rate and impurity content. If you expect to obtain a relatively high-quality film such as a diamond film, you need a high vacuum level, such as 10⁻ 6 Torr, if you want to increase the deposition rate, the vacuum degree can be lowered, such as 10⁻ 3 Torr, in other words, the higher the vacuum degree, the better the quality of the resulting crystal, and the lower the vacuum degree, the higher the deposition rate.

[0047] The vacuum pumping device generally adopts a vacuum pump group, specifically a combination of a molecular pump + a mechanical pump. This is common knowledge in the field and will not be elaborated here.

[0048] The reaction gas is distributed to the deposition chamber through a gas control device. Again, as mentioned above, this is common knowledge in the art, and the embodiments of the present invention do not involve how to distribute the gas. As common knowledge, a gas control device is usually used to accurately control the flow and proportion of the reaction gas, and it usually contains a mass flow controller (MFC) for real-time monitoring of the gas input to ensure the sustainability of the process. At the same time, it should be known that the deposition rate, crystal quality and doping characteristics can be controlled by controlling the proportion and flow of the gas.

[0049] It should be known that crystals are not always required to be completely pure, and in some implementations they need to be doped, for example semiconductor crystals are often doped to produce doped crystals.

[0050] In addition, the deposition chamber is also equipped with a substrate heating and temperature control system. There are currently two main heating methods, one is resistance heating and the other is infrared heating. The substrate is heated by heat conduction or radiation to reach a predetermined temperature, such as 500°C~1200°C.

[0051] The object to be heated is the substrate, not other components. For example, the magnetron, the resonant cavity, and the growth base 12 used to support the substrate need to be prevented from overheating. Therefore, a cooling system is often required to cool the components that do not need to be heated or even need thermal protection on the periphery of the deposition chamber.

[0052] In the embodiments of the present invention, the heating and cooling devices in the MPCVD equipment are also general applications of the heating and cooling devices in the art, which will not be described in detail here. The improved parts can be described separately, but other configurations will not be described in detail. For example, Figure 2 The heat dissipation holes 39 provided on the metal enclosure 38 are mainly used for cooling the resonance cavity. The cooling gas flows through the heat dissipation holes 39 in the resonance cavity. Other configurations will not be described again.

[0053] In addition, general MPCVD equipment is also equipped with a monitoring and control system, mainly including a spectrometer, which obtains the spectrum of the plasma in the deposition chamber in real time through online monitoring to monitor the reaction progress and the types of active groups, so as to control the microwave power, gas flow, temperature and partial pressure, etc. This is common knowledge in the field and will not be elaborated here.

[0054] Regarding the lifting and lowering control of the growth base 12, a lifting device is mainly used. Figure 1 In the illustrated structure, the lifting device is a two-stage lifting device, but the growth base 12 can also be adjusted by a single-stage lifting device.

[0055] The lifting device is arranged on the frame 1 and drives the lifting of the growth platform 12 by intervening in the deposition chamber, so that the deposition surface of the substrate on the growth platform 12 is always located at a predetermined height of the deposition chamber during the growth process.

[0056] exist Figure 1 In the illustrated structure, the first-stage lifting device includes a first guide rod 2, a first lifting plate 4, a first slide 35, a first lifting mechanism 36 and a first-stage lifting motor 31, wherein the first guide rod 2 is vertically arranged, and its upper and lower ends are fixed on the frame 1 to provide vertical guidance.

[0057] The guide rod and guide sleeve pair is a relatively simple guide pair in the mechanical field. Another more common guide pair is the guide rail pair. In the embodiment of the present invention, both the two-stage lifting devices preferably use the guide rod and guide sleeve pair.

[0058] Correspondingly, a first guide hole is formed on the first lifting plate 4, and a first guide sleeve 34 is embedded or installed in the first guide hole. The first guide sleeve 34 cooperates with the first guide rod 2 to form a first guide rod-guide sleeve pair.

[0059] Figure 1 In the embodiment, the first slide 35 is fixedly connected to the first lifting plate 4. Figure 1 The first lifting mechanism 36 is vertically arranged on the right side of the figure, and the first lifting mechanism preferably adopts a first nut-and-screw pair with relatively high driving accuracy.

[0060] The nut-screw mechanism is a mechanism used in the mechanical field to achieve precise driving. For example, the common driving mechanism on CNC machine tools is usually a ball screw mechanism. Therefore, in the embodiments of the present invention, the nut-screw mechanism used also adopts a ball screw mechanism.

[0061] Figure 1 In the embodiment, the first slide seat 35 is used to install the first screw nut on the first screw nut pair and to drag the first lifting plate 4.

[0062] Furthermore, the second lifting device includes a pedestal 30, a chamber base 9, a chamber base sealing plate 7, a secondary lifting motor 3, a second lifting nut screw pair 5, a second nut frame 6, and a second guide rod 33, wherein the upper end of the second guide rod 33 is fixed on the chamber base 9, and the lower end is fixed on the first lifting plate 4. At this time, the second guide rod 33 first constitutes a connecting rod to form a lifting assembly with the chamber base 9 and the first lifting plate 4.

[0063] Correspondingly, the pedestal 30 is used to support the deposition chamber and is formed with a sealing stopper, which is obviously downward and can be a concave stopper or a convex stopper, with the concave stopper being preferred to facilitate the formation of a joint seal with the chamber base 9. The upper end of the chamber base 9 is formed with a convex stopper or a concave stopper corresponding to the sealing stopper, hereinafter referred to as the lower stopper.

[0064] Since the sealing assembly is driven by the first lifting device, in other words, the chamber base 9 can be engaged or disengaged with the pedestal 30 through the first lifting device, that is, the lower chamber opening can be opened and closed by engaging or disengaging the lower stop and the sealing stop.

[0065] Furthermore, the chamber base sealing disc 7 is guided by the second guide rod 33, that is, the distance between the chamber base sealing disc 7 and the chamber base 9 is variable. The two are connected by a first sealing spring sealing tube 8, which is preferably a metal bellows. With the help of the first sealing spring sealing tube 8, the seal can be changed to a static seal, thereby achieving a better sealing ability.

[0066] Correspondingly, a second nut frame 6 is provided on the lower side of the chamber base sealing disk 7 . The second nut frame 6 is generally a U-shaped frame, and may also be other frames to adapt to the activity space of the second lifting nut screw pair 5 .

[0067] Furthermore, the second screw nut of the second lifting screw nut screw pair 5 is installed on the second screw nut frame 6, and the second screw adopts Figure 1 The two-stage lifting motor 3 shown in the example is driven.

[0068] The chamber base sealing plate 7 supports the growth base 12 through a rigid tubular body or a support rod, and the position of the growth base 12 in the deposition chamber can be adjusted through the second lifting screw nut lead screw pair 5.

[0069] Based on the above structure of the lifting device, on the one hand, the substrate can be placed on the growth base 12 after the growth base 12 exits the deposition chamber from the lower chamber port; on the other hand, the growth base 12 is lifted and lowered by controlling the second lifting screw nut 5 to place it in a suitable position in the deposition chamber.

[0070] For example, the first lifting mechanism drives the first lifting plate 4 to lift the second lifting device as a whole, and drives the growth base 12 to enter and exit the lower chamber port, and at the upper dead point of the upward stroke, the chamber base 9 is engaged with the pedestal 30 to form a static seal.

[0071] Under the condition of providing driving to the growth base 12, the dynamic seal is converted into a static seal by means of the first sealing spring sealing tube 8 in the second lifting device, so as to improve the overall sealing ability.

[0072] Next, let's look at the third invention point, namely, how to effectively control the range of microwave feeding so that the microwave energy can act more concentratedly on the predetermined position of the deposition chamber.

[0073] exist Figure 1 and Figure 2 In the embodiment, the resonant cavity has a cover nested outside the deposition chamber, and the cover is made of metal, such as an aluminum alloy cover 38.

[0074] A given distance is left between the enclosure and the deposition chamber, and the given distance is 8-13% of the diameter of the deposition chamber. One purpose of leaving the given distance is to facilitate the feeding and homogenization of microwaves, and another purpose is to facilitate the cooling of the enclosure.

[0075] First, let's look at the feed. A microwave feed slot 37 is distributed in the middle of the enclosure in the vertical direction. Figure 2It can be seen that the microwave feeding slots 37 are distributed in a relatively small range. In other words, they limit the range of crystal growth to be relatively small. As the crystal grows, the height of the surface on which the crystal grows is controlled by the second lifting device so that it is always in the functional area where the microwave feeding slots 37 are located.

[0076] The distribution range of the microwave feeding slot 37 in the height direction of the deposition chamber is about 50 mm in the middle thereof, and can generally be 45 mm to 60 mm.

[0077] The height of the quartz tube 13 can generally be 200-300 mm, and the tube wall thickness is 1-5 mm. It can be seen that the coverage range of the microwave feeding slot 37 is relatively small.

[0078] Correspondingly, the deposition chamber has a quartz tube 13 which, together with the chamber sealing upper cover and the chamber sealing lower cover, forms a furnace cavity. The microwave feeding gap 37 determines the feeding range and further determines the quartz window of the quartz tube.

[0079] Correspondingly, the surface of the growth base 12 for supporting the substrate is located within the quartz tube section defined by the microwave feeding slot 37 .

[0080] It should be known that in MPCVD equipment, the growth rate of the deposited material varies greatly due to differences in deposition materials, deposition requirements, etc., and the growth rate is generally between 0.1 and 100 μm / h. It can be seen that the coverage range of the aforementioned microwave feeding slot 37 does not need to be too large. The larger coverage range of the microwave feeding slot relative to the growth rate mainly makes the plasma generated by the ionization of the reaction gas relatively uniform. Therefore, the current growing surface is roughly located in the upper middle of the height segment of the deposition chamber covered by the microwave feeding slot 37, which is about 60% to 75% of the height segment.

[0081] In order to obtain a better plasma range, the microwave feeding slot 37 includes a transverse slot and a vertical slot, wherein the transverse slot is evenly distributed in the vertical direction, which can optimize the interference of microwaves as a whole, thereby helping to homogenize the coupling of microwaves and reaction gases as a whole.

[0082] Preferably, there are two groups of microwave feeding slots 37, one group being arranged on opposite sides of the enclosure, one side being the side where the microwave duct is located, and the other side must be the side opposite to the side, so that the microwave can better resonate in the resonance cavity.

[0083] In addition, preferably, the widths of the transverse slots and the vertical slots in the group of microwave feeding slots 37 are the same, and the vertical slots pass through the transverse slots in the vertical center.

[0084] The angle between the transverse slot and the vertical slot is 60° to 90°; the length of the vertical slot is the same as the length of the transverse slot; the aspect ratio of the transverse slot is 20:1 to 15:1, and the length of the microwave feeding slot 37 is 45 mm to 60 mm.

[0085] As mentioned above, the temperature in the deposition chamber is relatively high, even up to 1200°C, while the heat resistance temperature of the metal enclosure 38, such as aluminum alloy, is relatively low. Therefore, heat dissipation holes 39 are provided on the upper and lower parts of the enclosure, and a given distance between the enclosure and the deposition chamber is used to form a cooling channel, and the circulating cooling air maintains a relatively low temperature of the enclosure.

[0086] The heat dissipation flow rate is 5~30m 3 / h, which ensures the cooling of the resonant cavity while effectively protecting the microwave generation and transmission equipment.

[0087] Next, let's look at the second invention point, which is to optimize the nucleation, growth and performance of the film by loading a bias electric field and regulating the movement path of charged particles in the plasma.

[0088] In the embodiment of the present invention, an independent electrode is arranged outside the deposition chamber, which is called an external electrode; an electrode may also be arranged below the substrate, that is, on the growth base 12, which is called an internal electrode.

[0089] Furthermore, the chamber sealing upper cover 14 has an upper center hole, and a bias device metal bottom plate is installed on the chamber sealing upper cover 14 to construct an external electrode sheet. Accordingly, a bias device is provided outside the chamber sealing upper cover 14 to apply a positive electric field to the microwave plasma through the bias device metal bottom plate.

[0090] The applied positive electric field is realized by DC bias, and the voltage of the positive bias set by the DC bias is 50~100V. The size of the rectifier bias can be adjusted according to the crystal growth conditions.

[0091] Since the positive bias voltage is located on the chamber sealing cover 14, the generated electric field will cause the positive ions H⁺, CH 3 ⁺Move downward and bombard the substrate surface, creating local defects or etching non-diamond phases, such as amorphous carbon, to promote the formation of diamond nuclei.

[0092] If the inner electrode is provided separately, the voltage loaded on the inner electrode is a negative voltage.

[0093] Correspondingly, if the inner electrode and the outer electrode are provided at the same time, similarly, the voltage loaded on the outer electrode is a positive voltage, and the voltage loaded on the negative electrode is a negative voltage.

[0094] It should be known that the metal bottom plate of the biasing device needs to be electrically isolated from the deposition chamber to avoid short circuit. Relatively speaking, the chamber sealing cover 14 can be made of insulating materials such as insulating ceramics or quartz.

[0095] exist Figure 1 In the upper part, the illustrated structure is applicable to an example having both an inner electrode and an outer electrode. The molybdenum metal cylinder 18 shown in the figure is used as a connecting electrode, which extends downward into the deposition chamber to make contact with the substrate, and is conducted from the substrate to the inner electrode or the inner electrode is directly constituted by the substrate.

[0096] It should be noted that, although both graphite and diamond are carbon single substances, graphite has good electrical conductivity, while diamond is an insulator. The substrate material for the growth of diamond film is usually a material with a high melting point. Some substrates have good electrical conductivity, such as copper substrates, titanium substrates, etc. Even if the substrate is not conductive, a conductive electrode sheet can be set on the lower side of the substrate to form an internal electrode. Under this condition, the substrate needs to be provided with a perforation so that, for example, the aforementioned molybdenum metal cylinder 18 can pass through and contact the electrode sheet.

[0097] Furthermore, in a preferred embodiment, the biasing device further comprises: The fourth guide assembly is disposed on the chamber sealing cover 14 to provide vertical guidance, such as Figure 1 The fourth guide rod 26 shown in FIG. 1 is fixed on the chamber sealing cover 14. Figure 1 The illustrated structure also has a base plate 28 to facilitate integration of the fourth guide assembly into an assembly.

[0098] Furthermore, a fourth slide 27 guided on the fourth guide rod 26 is provided, and a fourth guide sleeve is provided on the fourth slide 27 to cooperate with the fourth guide rod 26 to form a fourth guide pair.

[0099] In order to achieve better sealing, the fourth slide 27 is connected to the chamber sealing cover 14 by a second sealing spring sealing tube 16. The second sealing spring sealing tube 16 also adopts a metal bellows, and because it is located outside the deposition chamber, a plastic bellows, such as a PC bellows, can be used.

[0100] Furthermore, a metal cylinder fixedly mounted on the fourth slide 27 is provided, such as the molybdenum metal cylinder 18 mentioned above, one end of which is inserted into the deposition chamber through the upper center hole opened on the chamber sealing cover 14.

[0101] Correspondingly, the other end of the metal cylinder protrudes from the upper end of the fourth slide seat 27 or is connected to a probe electrode 19 for external power supply.

[0102] Furthermore, a pair of third guide rods 24 are fixedly arranged at the upper end of the fourth slide 27, and the corresponding two third guide rods 24 are interconnected by a cross beam. A clamping rod is also provided, which is installed on the cross beam, so that the fourth slide 27 is clamped by the clamping rod after the fourth slide 27 is adjusted into place, so that the molybdenum metal cylinder 18 installed at the lower end of the fourth slide 27 is fully engaged with the inner electrode.

[0103] Specifically, a nut 21, a screw sleeve or a threaded hole is provided on the cross beam. If a nut 21 or a screw sleeve is provided, for example, the nut 21 can be welded to the cross beam. The clamping rod can be a screw rod 20 matched with the nut 21, for example, to clamp the fourth slide seat 27 by the screw lift force.

[0104] As mentioned above, since the quartz tube 13 is first evacuated, during the evacuation process, as the vacuum degree in the quartz tube 13 gradually increases, even without external force, the fourth slide 27 will gradually compress the second sealing spring sealing tube 16 due to the internal and external pressure difference until the molybdenum metal cylinder 18 comes into contact with the inner electrode. Considering that the pressure formed by atmospheric pressure is not enough to produce a good electrical connection, an external force is further applied using, for example, a screw 20, so that, for example, the molybdenum metal cylinder 18 comes into good contact with the inner electrode to form a better electrical connection.

Claims

1. An MPCVD device, characterized in that: include: frame; The deposition chamber is vertically arranged on the frame and has an upper chamber opening and a lower chamber opening, wherein the upper chamber opening is provided with a chamber sealing upper cover, and the lower chamber opening is provided with a chamber sealing lower cover with a lifting hole; a quartz window is provided at a predetermined position on the side wall of the deposition chamber; and a growth base is provided in the deposition chamber; The resonant cavity is arranged outside the deposition chamber and is functionally connected to the deposition chamber through a quartz window; A microwave generating and transmitting device is connected to the resonant cavity through a microwave conduit so that the microwave can pass through the quartz window to ionize the reaction gas; A vacuum pumping device is inserted into the deposition chamber to vacuum the deposition chamber; a gas control device connected to the deposition chamber to provide reaction gas to the deposition chamber; The lifting device is arranged on the frame, and drives the growth base to rise and fall by intervening in the deposition chamber, so that the deposition surface of the substrate on the growth base is always located at a predetermined height of the deposition chamber during the growth process.

2. The MPCVD device according to claim 1, characterized in that: The resonant cavity has a cover nested outside the deposition chamber, and a given distance is left between the cover and the deposition chamber; The enclosure is provided with microwave feeding slots in the middle of the vertical direction; Correspondingly, the deposition chamber has a quartz tube which is surrounded by a chamber sealing upper cover and a chamber sealing lower cover to form a furnace cavity, and the microwave feeding gap determines the feeding range and further determines the quartz window of the quartz tube; The surface of the growth base for supporting the substrate is located in the quartz tube section determined by the microwave feeding gap.

3. The MPCVD device according to claim 2, characterized in that: The microwave feeding slots include transverse slots and vertical slots, wherein the transverse slots are evenly distributed in the vertical direction.

4. The MPCVD device according to claim 3, characterized in that: There are two groups of microwave feeding slots, one group is arranged on two opposite sides of the enclosure, one side of which is the side where the microwave guide tube is located.

5. The MPCVD device according to claim 4, characterized in that: The width of the transverse slot and the vertical slot in the microwave feeding slot group are the same, and the vertical slot passes through the transverse slot in the center in the vertical direction.

6. The MPCVD device according to claim 5, characterized in that: The angle between the horizontal gap and the vertical gap is 60°~90°; The length of the vertical gap is also the same as the length of the horizontal gap; The aspect ratio of the transverse slot is 20:1~15:1, and the length of the microwave feeding slot is 45mm~55mm.

7. The MPCVD device according to any one of claims 2 to 6, characterized in that: The upper part and the lower part of the enclosure are provided with heat dissipation holes.

8. The MPCVD device according to claim 1, characterized in that: The chamber sealing upper cover has an upper center hole, and a metal bottom plate of a biasing device is mounted on the chamber sealing upper cover; Correspondingly, a bias device is provided outside the chamber sealing upper cover to apply a positive electric field to the microwave plasma through the metal bottom plate of the bias device.

9. The MPCVD device according to claim 8, characterized in that: The biasing device further comprises: The fourth guide assembly is disposed on the chamber sealing cover to provide guidance in the up-down direction; A fourth slide seat is guided by the fourth guide assembly, the fourth slide seat is connected to the chamber sealing upper cover by a second sealing spring sealing tube, and a metal cylinder is fixedly connected to the center, one end of the metal cylinder is inserted into the deposition chamber through the upper center hole, and the other end of the metal cylinder protrudes from the upper end of the fourth slide seat or is connected to a probe electrode; A pair of third guide rods are arranged in parallel at the upper end of the fourth slide, and the corresponding two third guide rods are interconnected by a crossbeam; A clamping rod is installed on the cross beam so as to press down the fourth slide seat through adjustment of the clamping rod after the fourth slide seat is adjusted into place.

10. The MPCVD device according to claim 1, characterized in that: The lifting device comprises: A first lifting device, mounted on the frame and having a first lifting plate; The second lifting device includes a pedestal, a chamber base, a chamber base sealing disk and a driving device for driving the chamber base sealing disk, wherein the pedestal is fixed on the frame to support the sealed chamber, and the pedestal is configured with a sealing stop; the chamber base sealing disk and the chamber base constituting the chamber sealing lower cover are connected by a first sealing spring sealing tube; the chamber base and the first lifting disk are supported and connected by a second guide rod, and are opened and closed by the driving of the first lifting device with the sealing stop; the chamber base sealing disk is used to support the growth base, and the chamber base sealing disk controls the growth base to rise and fall under the lifting drive of the driving device.

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