A method for assembling a chemical vapor deposition furnace

Abstract

The present invention discloses a chemical vapor deposition furnace, comprising a furnace body, a deposition chamber is arranged in the furnace body, the top of the deposition chamber is connected to a vacuum pipeline, the bottom of the deposition chamber is arranged on a crucible cover, a raw material crucible is arranged at the bottom of the crucible cover, and a gas introduction device is also arranged on the surface of the crucible cover corresponding to the deposition chamber; the gas introduction device comprises a plurality of gas boxes arranged in parallel, a plurality of gas nozzles are arranged on the gas box, two adjacent gas boxes are respectively connected to the raw material crucible and the mixed raw material gas inlet channel, the raw material crucible is also connected to the carrier gas inlet channel, and a gas distribution plate is arranged in the gas box. The present invention can significantly improve the uniformity of the raw material ratio of the deposition space, and it is easier to deposit and obtain a product with a larger area and uniform thickness.

Description

Technical Field

[0001] The invention relates to the technical field of chemical vapor deposition, and in particular to an assembling method of a chemical vapor deposition furnace. Background Art

[0002] Chemical vapor deposition (CVD) has been widely used to prepare various inorganic materials: such as fiber materials for composite materials (such as B, B4C), thin layer materials for diffusion barrier layers (such as ZrO2), powder materials for fine ceramics (such as Al2O3, SiC), and polycrystalline bulk materials for infrared windows (such as ZnS, ZnSe). Among them, the use of CVD technology to prepare ZnS and ZnSe crystals has the advantages of high purity, high density, low absorption, excellent optical properties, etc., and it is easy to achieve large-size material preparation. It is currently the mainstream technology for producing ZnS and ZnSe materials.

[0003] The technical solution for preparing ZnS (ZnSe) by chemical vapor deposition (CVD) technology is as follows: the bottom of the furnace chamber is a crucible containing raw material Zn, and the upper part is a deposition chamber composed of graphite plates. The crucible and the deposition chamber are first heated to the set temperature respectively, and then the carrier gas Ar is introduced into the surface of the molten Zn, carrying the Zn vapor into the deposition chamber. At the same time, the H2S (H2Se) gas is also transported to the deposition chamber after being diluted by Ar. H2S (H2Se) and Zn react on the graphite plate to generate solid ZnS (ZnSe). After a period of deposition, a block polycrystalline ZnS (ZnSe) material of a certain thickness can be finally obtained.

[0004] With the development of the infrared market, the demand for large-size ZnS (ZnSe) materials and large-scale production of materials is becoming more and more urgent. In the specific implementation of this technical process, since the required products are mostly large-size plates, the deposition chamber is mostly a rectangular structure and large-size preparation. After the deposition furnace is enlarged, the deposition chamber space becomes larger and the deposition cycle needs to be longer. Therefore, the most critical issue is how to solve the uniformity problem of large-size materials.

[0005] Due to the large space of the deposition chamber, in existing equipment, both H2S (H2Se) and Zn vapor raw materials enter the deposition chamber through multiple holes. The H2S (H2Se) gas is controlled by a multi-channel gas mass flow meter to keep the gas flow of each hole consistent. However, Zn vapor is carried into the deposition chamber by Ar gas passing over the molten Zn liquid surface in the crucible. Therefore, it is difficult to ensure that the gas flow of each Zn outlet hole remains consistent. This will cause differences in the ratio of reactants Zn and H2S (H2Se) in the space, resulting in certain differences in the structure and performance of the materials deposited at different positions, and poor uniformity. This will seriously affect the quality of the product in actual production, especially in large-scale production. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide an assembly method of a chemical vapor deposition furnace, which can significantly improve the uniformity of the raw material ratio in the deposition space and make it easier to deposit a product with a larger area and uniform thickness.

[0007] In order to solve the above technical problems, the present invention provides a chemical vapor deposition furnace, comprising a furnace body, a deposition chamber is arranged in the furnace body, the top of the deposition chamber is connected to a vacuum pipe, the bottom of the deposition chamber is arranged on a crucible cover, a raw material crucible is arranged at the bottom of the crucible cover, and a gas introduction device is also arranged on the surface of the crucible cover corresponding to the deposition chamber;

[0008] The gas introduction device includes a plurality of gas boxes arranged in parallel, each of which is provided with a plurality of gas nozzles, two adjacent gas boxes are respectively connected to the raw material crucible and the mixed raw material gas inlet channel, the raw material crucible is also connected to the carrier gas inlet channel, and a gas distribution plate is provided in the gas box.

[0009] Furthermore, a containing cavity is arranged on the surface of the crucible cover, the gas box is arranged in the containing cavity, and the mixed raw material gas inlet channel and the carrier gas inlet channel are both arranged on the crucible cover.

[0010] Furthermore, three continuous step supports are arranged in the gas box, the number of the gas distribution plates is 2, a plurality of gas nozzles are arranged on the top plate, two gas distribution plates are arranged on two step supports at the lower part of the gas box, and the top plate is arranged on the top step support.

[0011] Furthermore, the holes on the two gas distribution plates are staggered, and no holes are provided at corresponding positions on the gas distribution plates corresponding to the mixed raw material gas inlet channels.

[0012] Furthermore, the number of the gas boxes is 3, two of which are connected to the deposition chamber, and the other gas box is arranged in the middle and is connected to the mixed raw material gas inlet channel.

[0013] Furthermore, the crucible cover is arranged on a trolley, a trolley track frame is arranged in the furnace body corresponding to the trolley, a lifting platform is arranged under the trolley, the raw material crucible is placed on the lifting platform, and the lifting platform is connected to the lifting mechanism.

[0014] Furthermore, a step frame is provided on the material cart, the crucible cover is arranged in the step frame, two rows of running wheels are provided at the bottom of the material cart, a concave limiting guide rail is provided on the material cart track frame corresponding to the running wheels, and a front locking block and a rear locking block are provided on the concave limiting guide rail.

[0015] Furthermore, the lifting mechanism includes a screw lift and a lifting and lifting plate, the screw lift is installed on a lifting support base, the lifting support base is set on a material cart, the screw lift is also connected to the lifting and lifting plate, and lifting rods are set on both ends of the lifting and lifting plate. The lifting rod passes through the material cart and is connected to the lifting platform, and a fixing nut is sleeved on the part of the lifting rod located above the material cart.

[0016] Furthermore, the lifting platform is provided with a crucible placement positioning recess, the crucible placement positioning recess is provided with a heating avoidance opening, and a support frame is provided in the furnace body below the lifting platform.

[0017] Furthermore, the furnace body is a single-sided door structure and the inner cavity is a rectangular parallelepiped, a water cooling device is provided on the outer wall of the furnace body, a deposition chamber heating element and insulation material are provided on the inner wall of the furnace body, and a crucible heating element is provided on the outer periphery of the raw material crucible.

[0018] Beneficial effects of the present invention:

[0019] The gas introduction device can make the evaporated raw material vapor and carrier gas in the raw material crucible evenly distributed and then enter the deposition chamber through a plurality of gas nozzles, which can ensure the consistency of the gas flow rate and concentration of the first raw material in each gas nozzle; the gas introduction device can also make the second raw material gas and the dilution gas evenly distributed and then enter the deposition chamber through a plurality of gas nozzles. The above structure simplifies the gas intake structure and avoids the setting of multiple flow meters and pipelines for the first raw material gas and the dilution gas, and ensures the consistency of the gas flow rate and concentration in each gas nozzle, so that the concentration distribution of the two raw material gases in a larger deposition space is more uniform;

[0020] The setting of the gas distribution plate can effectively filter out impurities such as particles and oxide scale that enter the deposition chamber along with the raw material gas in the crucible. The comprehensive performance of the products prepared by deposition is greatly improved, and it is easier to deposit and obtain optically uniform products on a larger area and thickness scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention;

[0022] Figure 2 is a schematic diagram of the deposition structure of the present invention;

[0023] Figure 3 It is a schematic diagram of the gas raw material supply structure of the present invention;

[0024] Figure 4 yes Figure 3 Explosion diagram of some structures;

[0025] Figure 5 It is a schematic diagram of the explosion of the gas introduction device of the present invention;

[0026] Figure 6 It is a schematic diagram of the bottom structure of the crucible cover of the present invention;

[0027] Figure 7 is a schematic diagram of the overall structure of another embodiment of the present invention;

[0028] Figure 8 yes Figure 7 Schematic diagram of the coordination between the intermediate material car and the deposition structure;

[0029] Fig. 9 yes Figure 7 Schematic diagram of the structure of the middle material car. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0031] Reference Figures 1 to 6 As shown, an embodiment of the chemical vapor deposition furnace of the present invention includes a furnace body 1, a deposition chamber 2 is arranged in the furnace body, the top of the deposition chamber is connected to the vacuum pipe 3, the bottom of the deposition chamber is arranged on the crucible cover 4, a raw material crucible 5 is arranged at the bottom of the crucible cover, and a gas introduction device 61 is also arranged on the surface of the crucible cover corresponding to the deposition chamber; the gas introduction device can introduce two raw material gases into the deposition chamber with uniform concentration distribution in a larger deposition space, which is conducive to the preparation of high-quality products.

[0032] The above-mentioned gas introduction device includes a plurality of gas boxes 6 arranged in parallel, and a plurality of gas nozzles 7 are arranged on the gas boxes. Two adjacent gas boxes are respectively connected with the raw material crucible and the mixed raw material gas inlet channel 8, and the raw material crucible is also connected with the carrier gas inlet channel 9, wherein the two adjacent gas boxes are respectively a first raw material gas box and a second raw material gas box, and the carrier gas inlet channel is used to pass the carrier gas into the raw material crucible. The first raw material is stored in the raw material crucible. The carrier gas passes through the first raw material and passes into the first raw material gas box, while the second raw material gas is directly mixed with the dilution gas and passes into the second raw material gas box from the mixed raw material gas inlet channel; a gas distribution plate 10 is arranged in the gas box, and the gas distribution plate divides the interior of the gas box into a plurality of chambers. When the gas enters, the gas distribution plate can evenly distribute the gas, and then discharge it from a plurality of gas nozzles. The gas flow rate and concentration discharged from the plurality of gas nozzles are consistent.

[0033] The furnace body is a single-sided door structure and the inner cavity is a rectangular parallelepiped. The inner cavity of the rectangular parallelepiped furnace body cooperates with the square deposition chamber to maximize the use of the furnace body space, improve productivity, and is more conducive to achieving temperature uniformity in the large deposition chamber. A water cooling device is provided on the outer wall of the furnace body, and a deposition chamber heating element 27 and a heat-insulating material 28 are provided on the inner wall of the furnace body. A crucible heating element 29 is provided on the outer periphery of the raw material crucible. The heat-insulating material can be a carbon felt material or a refractory ceramic material. The deposition chamber heating element and the crucible heating element can be a graphite heater.

[0034] When in use, the first raw material in the raw material crucible is heated and evaporated by the crucible heating element to form a first raw material gas. After the carrier gas is introduced into the raw material crucible, it will carry the first raw material into the first raw material gas box. The first raw material gas box evenly distributes the mixed gas of the first raw material gas and the carrier gas through the gas distribution plate, and the gas is evenly discharged from multiple gas nozzles after distribution; the second raw material is mixed with the dilution gas in the mixing tank and directly introduced into the second raw material gas box. The first raw material gas box evenly distributes the mixed gas of the second raw material gas and the dilution gas through the gas distribution plate, and the gas is evenly discharged from multiple gas nozzles after distribution; then the two raw materials are effectively deposited in the deposition chamber to obtain the product.

[0035] Specifically, the surface of the crucible cover is provided with a receiving cavity 11, and the gas box is arranged in the receiving cavity, which does not occupy the space of the deposition chamber. The mixed raw material gas inlet channel and the carrier gas inlet channel are both arranged on the crucible cover, which are prepared by opening holes, have a simple structure, no pipeline arrangement, and have high reliability. Three continuous step supports 12 are arranged in the gas box, and the number of gas distribution plates is 2. A plurality of gas nozzles are arranged on the top plate 13. Two gas distribution plates are arranged on the two step supports located at the lower part of the gas box, and the top plate is arranged on the step support at the top. The two gas distribution plates divide the inside of the gas box into three chambers, that is, after two uniform distributions, they are discharged from the gas nozzles, which effectively ensures the uniformity of distribution. The holes on the two gas distribution plates are also staggered, so that the gas will not directly enter from one chamber into another chamber, which effectively improves the effect of uniform mixing and the ability of uniform distribution. In addition, no holes are provided at the corresponding positions on the gas distribution plates corresponding to the mixed raw material gas inlet channel, so as to prevent the gas from directly entering the second chamber.

[0036] The number of the above-mentioned gas boxes is limited to 3, of which two gas boxes are first raw material gas boxes, and the other is a second raw material gas box. The second raw material gas box is arranged in the middle of the two first raw material gas boxes, the two first raw material gas boxes are through-connected with the deposition chamber, and the second raw material gas box is through-connected with the mixed raw material gas inlet channel. Since the deposition chamber is symmetrical, the above-mentioned structure of symmetrical arrangement of the second raw material gas box along the middle is designed, and the gas nozzle corresponding to the second raw material is arranged on the central axis, and the gas nozzles corresponding to the first raw material are respectively on both sides. There is a deposition plate on each side of the two groups of first raw material gas nozzles, thereby ensuring the consistency of the left and right deposition plates.

[0037] Reference Figures 7 to 9 As described, in one embodiment, the crucible cover is arranged on a trolley 14, a trolley track frame 15 is arranged in the furnace body corresponding to the trolley, a lifting platform 16 is arranged under the trolley, the raw material crucible is placed on the lifting platform, and the lifting platform is connected to the lifting mechanism 17. By cooperating with the trolley and the trolley track frame, the crucible cover and the deposition chamber can be pushed into the deposition furnace from the outside, and the crucible cover and the deposition chamber can be assembled outside, with a large space and convenient operation. After the deposition is completed, the crucible cover and the deposition chamber can be pulled out as a whole and disassembled outside, which is very convenient to use. The lifting mechanism can drive the lifting platform to move up and down. When the trolley is delivered to the position, the lifting platform rises, lifts the raw material crucible and contacts and seals it with the bottom of the crucible cover. This method greatly reduces the difficulty of assembly in the existing furnace, and the operation is convenient and reliable.

[0038] Specifically, a step frame is provided on the material cart, the crucible cover is provided in the step frame, two rows of running wheels 18 are provided at the bottom of the material cart, a concave limit guide rail 19 is provided on the material cart track frame corresponding to the running wheels, and a front locking block and a rear locking block are provided on the concave limit guide rail. The material cart slides and moves in the concave limit guide rail, moves smoothly, has high reliability, can bear a large weight, and is fixed in position after being locked by the front locking block and the rear locking block. The lifting mechanism is also combined with the material cart, so as to fix the relative position of the lifting platform and the material cart, that is, the position of the raw material crucible and the crucible cover is determined, and the accuracy of the contact seal is ensured. The above-mentioned lifting mechanism includes a screw lift 20 and a lifting and lifting plate 21, the screw lift is installed on a lifting support base 22, the lifting support base is provided on the material cart, the screw lift is also connected to the lifting and lifting plate, and lifting suspension rods 23 are provided on both ends of the lifting and lifting plate, the lifting suspension rod passes through the material cart and is connected to the lifting platform, and a fixing nut 24 is sleeved on the part of the lifting suspension rod located above the material cart. A crucible placement positioning recess is provided on the lifting platform, and the raw material crucible is placed in the crucible placement positioning recess to further determine the relative position; a heating avoidance port 25 is provided on the crucible placement positioning recess to facilitate the heating of the raw material crucible, and a support frame 26 is provided in the furnace body below the lifting platform for placing the lifting platform.

[0039] Before deposition, the raw material crucible is placed on the lifting platform, and then the lifting platform is sent into the furnace body and placed on the support frame, and then the crucible heating element is arranged, and then the crucible cover and the deposition chamber are assembled outside the furnace body and placed on the material cart, and the material cart is pushed into the furnace body on the concave limit guide rail. After it is in place, the material cart is limited and fixed, and then the lifting mechanism accessories such as the lifting rod, lifting support base, lifting lifting plate and screw lift are installed from bottom to top. After the assembly is completed, the screw lift is activated, and the lifting lifting plate moves upward. The lifting lifting plate brings two lifting rods up, and the lifting rod pulls up the lifting platform, and the raw material crucible is lifted, and After the crucible cover is in contact and sealed, tighten the fixing nut on the lifting boom. The fixing nut fixes the lifting boom to the trolley (to ensure safety, the gap between the lifting platform and the support frame can be filled with pads for support after the lifting platform rises). Finally, remove the screw lift and related high-temperature-sensitive components in the lifting mechanism. After installation, production can be carried out. When dismantling the furnace, first install the removed components of the lifting mechanism in place, then loosen the fixing nut (remove the pads), and lower the raw material crucible until the lifting platform contacts the support frame. At this time, the trolley can be moved out of the furnace body. Of course, the lifting mechanism can also be removed first to avoid blocking the entry and exit of the deposition chamber. Move out of the deposition chamber and the furnace is dismantled.

[0040] The raw material crucible, lifting platform and crucible heating element do not need to be removed and can be directly used in the next deposition. The crucible heating element can be set by placing a thermocouple in contact with the raw material crucible after the raw material crucible is installed in place.

[0041] In one embodiment, the thermocouples arranged in contact on the four sides of the raw material crucible are also connected to a thermocouple lifting device, which is arranged outside the furnace body. A lifting transmission assembly passing through the furnace body is arranged between the thermocouple lifting device and the thermocouple. The thermocouple lifting device can drive the thermocouple to move vertically up and down along the surface of the raw material crucible to ensure that the speed at which the thermocouple temperature measuring point decreases during the deposition process is consistent with the speed at which the raw material liquid level in the raw material crucible decreases. The speed at which the raw material liquid level decreases is determined by calculating the relationship between the evaporation amount per unit time and the volume and density of the raw material liquid converted into steam. After the descent speed is obtained through simulation calculation, the crucible heating element is controlled to move up and down synchronously to ensure that the temperature of the raw material liquid level is always maintained at the set process temperature.

[0042] Specifically, by calculating the relationship between the evaporation amount of the raw material liquid and the change in liquid volume and density at a set temperature, the speed of liquid level drop is calculated, and the descent of the thermocouple is controlled by a controller, a motor, a reducer, etc., so that the thermocouple temperature measuring point is consistent with the liquid level height, which greatly reduces the phenomenon of unstable evaporation amount caused by the axial temperature gradient of the raw material crucible.

[0043] In summary, the gas distributor and thermocouple lifting device described in the present invention significantly improve the uniformity of the raw material ratio in the deposition space, significantly improve the consistency of the evaporation amount of the raw material liquid during long-term deposition, and make it easier to deposit optically uniform products on a larger area and thickness scale.

[0044] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for assembling a chemical vapor deposition furnace, characterized in that: The chemical vapor deposition furnace comprises a furnace body, a deposition chamber is arranged in the furnace body, the top of the deposition chamber is connected to a vacuum pipe, the bottom of the deposition chamber is arranged on a crucible cover, a raw material crucible is arranged at the bottom of the crucible cover, and a gas introduction device is also arranged on the surface of the crucible cover corresponding to the deposition chamber; The gas introduction device comprises a plurality of gas boxes arranged in parallel, the gas boxes are provided with a plurality of gas nozzles, two adjacent gas boxes are respectively connected to the raw material crucible and the mixed raw material gas inlet channel, the raw material crucible is also connected to the carrier gas inlet channel, and a gas distribution plate is provided in the gas box; The crucible cover is arranged on a trolley, a trolley track frame is arranged in the furnace body corresponding to the trolley, a lifting platform is arranged under the trolley, the raw material crucible is placed on the lifting platform, and the lifting platform is connected to the lifting mechanism; The material cart is provided with a step frame, the crucible cover is arranged in the step frame, two rows of running wheels are arranged at the bottom of the material cart, a concave limiting guide rail is arranged on the material cart track frame corresponding to the running wheels, and a front locking block and a rear locking block are arranged on the concave limiting guide rail; The lifting mechanism includes a screw lift and a lifting and lifting plate, the screw lift is installed on a lifting support base, the lifting support base is arranged on a material cart, the screw lift is also connected to the lifting and lifting plate, lifting rods are arranged on both ends of the lifting and lifting plate, the lifting rods pass through the material cart and are connected to the lifting platform, and a fixing nut is sleeved on the part of the lifting rod located above the material cart; The assembly method comprises: Before deposition, place the raw material crucible on the lifting platform, and then send the lifting platform into the furnace body. Then assemble the crucible cover and deposition chamber outside the furnace body and place them on the material cart. Push the material cart into the furnace body on the concave limit guide rail. After it is in place, limit and fix the material cart. Then install the lifting rod, lifting support base, lifting lifting plate and screw lift from bottom to top. After the assembly is completed, the screw lift moves, moving the lifting lifting plate upward. The lifting lifting plate rises with two lifting rods. The lifting rod pulls up the lifting platform and the raw material crucible. After it is sealed with the crucible cover, tighten the fixing nut on the lifting rod. The fixing nut fixes the lifting rod on the material cart. Finally, remove the screw lift and the installation is completed.

2. The method for assembling a chemical vapor deposition furnace according to claim 1, wherein: The surface of the crucible cover is provided with an accommodating cavity, the gas box is arranged in the accommodating cavity, and the mixed raw material gas inlet channel and the carrier gas inlet channel are both arranged on the crucible cover.

3. The method for assembling a chemical vapor deposition furnace according to claim 1, wherein: Three continuous step supports are arranged in the gas box, the number of the gas distribution plates is 2, a plurality of gas nozzles are arranged on the top plate, two gas distribution plates are arranged on two step supports at the lower part of the gas box, and the top plate is arranged on the top step support.

4. The method for assembling a chemical vapor deposition furnace according to claim 3, characterized in that: The holes on the two gas distribution plates are staggered, and no holes are provided at corresponding positions on the gas distribution plates corresponding to the mixed raw material gas inlet channels.

5. The method for assembling a chemical vapor deposition furnace according to claim 1, wherein: The number of the gas boxes is 3, two of which are connected to the deposition chamber, and the other gas box is arranged in the middle and is connected to the mixed raw material gas inlet channel.

6. The method for assembling a chemical vapor deposition furnace according to claim 1, wherein: The lifting platform is provided with a crucible placement positioning recess, the crucible placement positioning recess is provided with a heating avoidance opening, and a support frame is provided in the furnace body below the lifting platform.

7. The method for assembling a chemical vapor deposition furnace according to any one of claims 1 to 6, characterized in that: The furnace body is a single-sided door structure and the inner cavity is a rectangular parallelepiped. A water cooling device is arranged on the outer wall of the furnace body, a deposition chamber heating element and a heat preservation material are arranged on the inner wall of the furnace body, and a crucible heating element is arranged on the outer periphery of the raw material crucible.

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