A vertical liquid phase epitaxy graphite boat and growth device

Abstract

The utility model relates to a kind of perpendicular liquid phase epitaxy graphite boat and growth device, including crucible, sample holder and vapor cover are arranged in crucible, vapor cover cover is located in the outer periphery of sample holder;First recess and second recess are arranged in crucible;Separation position is arranged in second recess, and when vapor cover is located in separation position and below, its bottom is below mother liquor liquid level;Vapor cover can be connected with sample holder and enclosed to form sealed cavity when it is above separation position in first recess and second recess, and it is separated from sample holder when it is in separation position and below in second recess.The utility model forms sealed cavity to protect substrate by enclosing vapor cover with sample holder before the bottom of vapor cover drops below mother liquor liquid level in the process of mother liquor homogenization and before the bottom of vapor cover drops below mother liquor liquid level in the process of epitaxial growth, avoid substrate surface from being eroded by mercury vapor in the process of mother liquor homogenization stirring, and substrate surface contacts to the graphite particles suspended in mother liquor liquid level in the process of substrate dropping into mother liquor before growth, improve epitaxial material quality and product yield.

Description

Technical Field

[0001] This utility model relates to the field of liquid phase epitaxial growth technology of thin film materials, specifically to a vertical liquid phase epitaxial graphite boat and growth device. Background Technology

[0002] Liquid phase epitaxy (LPE) is currently the mature and mainstream technique for preparing mercury cadmium telluride (HCd) single-crystal thin films. In vertical liquid phase epitaxy, graphite growth boats are widely used. This is mainly due to the many excellent properties of graphite. First, graphite has good chemical stability, maintaining good chemical compatibility with the HCd mother liquor during LPE, avoiding chemical reactions and thus preventing adverse effects on the composition and properties of the mother liquor, ensuring the stability of epitaxial growth. Second, graphite has good thermal stability, maintaining structural integrity at the high temperatures required for LPE, and is not prone to thermal deformation or decomposition, providing stable support and carrier for epitaxial growth. Third, graphite has excellent machinability, easily processed into various complex shapes and structures, meeting the special design requirements of growth boats in vertical liquid phase epitaxy, such as precise dimensions, shapes, and various connection and positioning structures. However, graphite growth boats also have some problems. Among them, carbon contamination is a prominent issue. During the processing, assembly, and use of the growth boat, graphite materials easily generate tiny carbon particles. These particles may detach and enter the mother liquor during the movement of the growth boat, such as stirring or lifting operations. Since the density of carbon particles is generally lower than that of the mercury cadmium telluride mother liquor, they float on the surface of the mother liquor. When the substrate is immersed in the mother liquor for epitaxial growth, these carbon particles may adhere to the substrate surface, forming carbon contamination defects on the epitaxial surface. During epitaxial growth, carbon contamination can lead to defects such as interface striations. These defects severely affect the electrical and optical properties of the epitaxial film, reducing product yield. Utility Model Content

[0003] The purpose of this invention is to provide a vertical liquid phase epitaxial graphite boat and growth device, which can at least solve some of the defects in the prior art.

[0004] To achieve the above objectives, the technical solution of this utility model is a vertical liquid phase epitaxial graphite boat, including a crucible, a sample holder disposed inside the crucible, and a vapor hood disposed inside the crucible, the vapor hood covering the outer periphery of the sample holder; the crucible is provided with a first groove for limiting the vapor hood during the homogenization process of the mother liquor and a second groove for limiting the vapor hood during the epitaxial growth process; a separation position is provided in the second groove, the vapor hood can move up and down and switch between the first groove and the second groove, and when the vapor hood is in the separation position or below, its bottom is below the surface of the mother liquor; the vapor hood can connect with the sample holder and form a sealing cavity for sealing the substrate when it is above the separation position in the first groove and the second groove, and can separate from the sample holder when it is in the separation position in the second groove or below.

[0005] As one embodiment, a stirring base is also provided inside the crucible, a stirring rod is connected to the stirring base, and the sample holder is sleeved on the stirring rod.

[0006] As one embodiment, the second groove is further provided with a connection position, which is located above the separation position; the stirring rod is detachably connected to the bottom of the sample holder, and the stirring rod can be separated from the sample holder when the steam hood is located in the first groove and connected to the sample holder when the steam hood is located at or below the connection position in the second groove.

[0007] As one embodiment, the top of the sample holder is detachably connected to the top of the steam hood via a first threaded structure, and the bottom of the sample holder is detachably connected to the stirring rod via a second threaded structure, wherein the thread directions of the first threaded structure and the second threaded structure are opposite.

[0008] As one embodiment, both the first groove and the second groove extend in a vertical direction, with the top of the first groove and the top of the second groove being flush, and the bottom of the second groove being below the bottom of the first groove.

[0009] As one embodiment, the bottom of the steam hood is provided with an opening, and the bottom of the sample rack is provided with a sealing plate that can seal the opening.

[0010] As one embodiment, the steam hood includes a top plate and an annular side plate, the top of the annular side plate being connected to the top plate, and the bottom of the annular side plate forming the opening.

[0011] As one embodiment, the crucible includes an outer crucible and an inner crucible for holding the mother liquor. The inner crucible is made of boron nitride or glassy carbon material, and the outer crucible is made of graphite material. The sample holder and the outer surface of the vapor hood are coated with glassy carbon coating.

[0012] As one embodiment, a crucible lid is also included, which is detachably connected to the top of the crucible.

[0013] This utility model also provides a vertical liquid phase epitaxial growth apparatus, including the vertical liquid phase epitaxial graphite boat described in any of the above.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) In the process of homogenizing the mother liquor and before the bottom of the vapor hood in the epitaxial growth process descends below the surface of the mother liquor, the present invention encloses the vapor hood and the sample holder to form a sealed cavity to protect the substrate, so as to avoid the substrate surface being corroded by mercury vapor during the homogenization and stirring of the mother liquor and the substrate surface coming into contact with the graphite particles suspended on the surface of the mother liquor during the process of the substrate descending to the mother liquor before growth, ensuring that the substrate is only removed from protection after its bottom descends below the surface of the mother liquor, minimizing the contamination window period, thereby reducing surface defects of epitaxial materials, improving the quality of epitaxial materials and product yield;

[0016] (2) The present invention places the growth mother liquor in an inner crucible made of boron nitride or glassy carbon material, which can effectively prevent the molten mother liquor from contacting the outer crucible made of graphite material, thereby reducing the introduction of graphite particles in the mother liquor from the source; and coats the sample holder and vapor hood with glassy carbon coating to form an inert barrier, thereby blocking the dissolution of graphite particles into the mother liquor. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the structure of the vertical liquid phase epitaxial graphite boat provided in this embodiment of the utility model;

[0019] Figure 2 A schematic diagram of the sample holder provided in an embodiment of this utility model;

[0020] Figure 3 A schematic diagram of the installation of the steam hood in the first groove inside the crucible provided in an embodiment of this utility model;

[0021] Figure 4 A schematic diagram showing the installation of the steam hood in the second groove inside the crucible, as provided in an embodiment of this utility model;

[0022] Figure 5 A schematic diagram of the steam hood in the first groove inside the crucible provided in an embodiment of this utility model;

[0023] Figure 6 A schematic diagram showing the steam hood in the second groove inside the crucible, as provided in an embodiment of this utility model;

[0024] Figure 7 The image shows the interface of liquid phase epitaxial material after substrate removal, prepared using the unmodified graphite boat and method in the prior art.

[0025] Figure 8 The image shows the interface of the liquid phase epitaxial material prepared using the graphite boat and method of this embodiment after substrate removal.

[0026] Figure 9 A surface image of a liquid-phase epitaxial material prepared using an unmodified graphite boat and method in the prior art;

[0027] Figure 10 A surface view of the liquid phase epitaxial material prepared using the graphite boat and method of this embodiment;

[0028] In the figure: 1. Outer crucible; 11. First groove; 12. Second groove; 13. Third external thread; 14. Mounting part; 2. Inner crucible; 3. Steam hood; 31. Top plate; 32. Annular side plate; 33. Opening; 34. First internal thread; 35. End lug; 4. Sample holder; 41. Sample holder body; 42. Substrate fixing surface; 43. Upper part of sample holder; 44. Lower part of sample holder; 45. Sealing plate; 46. First external thread; 47. First shaft hole; 48. Second internal thread; 49. Screw hole; 5. Stirring base; 6. Stirring rod; 61. Second external thread; 62. Fourth external thread; 7. Connecting screw; 8. Crucible cover; 81. Third internal thread; 82. Second shaft hole. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0030] In the description of this utility model, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0032] like Figures 1-6 As shown, this embodiment provides a vertical liquid phase epitaxial graphite boat, including a crucible, a sample holder 4 disposed inside the crucible, and a vapor hood 3 disposed inside the crucible, the vapor hood 3 covering the outer periphery of the sample holder 4; the crucible is provided with a first groove 11 for limiting the vapor hood 3 during the homogenization process of the mother liquor and a second groove 12 for limiting the vapor hood 3 during the epitaxial growth process; the second groove 12 is provided with a separation position, the vapor hood 3 can move up and down and switch between the first groove 11 and the second groove 12, and when the vapor hood 3 is at or below the separation position, its bottom is below the mother liquor surface; the vapor hood 3 can connect with the sample holder 4 and form a sealing cavity for sealing the substrate when it is above the separation position in the first groove 11 and the second groove 12, and can separate from the sample holder 4 when it is at or below the separation position in the second groove 12. In this embodiment, before the bottom of the vapor hood descends below the mother liquor surface during the mother liquor homogenization process and the epitaxial growth process, the vapor hood 3 and the sample holder 4 are enclosed to form a sealed cavity to protect the substrate. This prevents the substrate surface from being chemically corroded by mercury vapor during the mother liquor homogenization stirring process and from contacting the substrate surface with graphite particles suspended on the mother liquor surface during the process of the substrate descending to the mother liquor before growth. This ensures that the substrate is only removed from protection after its bottom descends below the mother liquor surface, minimizing the contamination window period, thereby reducing surface defects of the epitaxial material, improving the quality of the epitaxial material and the product yield.

[0033] In some embodiments, a stirring base 5 is also provided inside the crucible, a stirring rod 6 is connected to the stirring base 5, and the sample holder 4 is sleeved on the stirring rod 6. For example... Figure 1As shown, the bottom of the stirring rod 6 is fixedly connected to the stirring base 5 by connecting screws 7. During the homogenization and cooling process before the start of the growth process, the stirring rod 6 can drive the stirring base 5 to stir the mother liquor, thereby achieving homogenization of the mother liquor.

[0034] In some embodiments, a connection position is also provided in the second groove 12, the connection position being located above the separation position; the stirring rod 6 is detachably connected to the bottom of the sample holder 4, and the stirring rod 6 can be separated from the sample holder 4 when the vapor hood 3 is located in the first groove and connected to the sample holder 4 when the vapor hood 3 is located at or below the connection position in the second groove. Since the stirring rod 6 is separated from the sample holder 4 when the vapor hood 3 is located in the first groove, the stirring rod 6 can drive the stirring base 5 to stir the mother liquor, thereby achieving homogenization of the mother liquor; while during epitaxial growth, the vapor hood 3 is located at or below the connection position in the second groove, and the stirring rod 6 is connected to the sample holder 4, so the stirring rod 6 can drive the sample holder 4 to descend to a designated position for epitaxial growth.

[0035] Preferably, the top of the sample holder 4 is detachably connected to the top of the steam hood 3 via a first threaded structure, and the bottom of the sample holder 4 is detachably connected to the stirring rod 6 via a second threaded structure. The thread directions of the first threaded structure and the second threaded structure are opposite. Due to the different thread directions of the first and second threaded structures, the stirring rod 6 can be connected to the sample holder 4 by rotating it when the steam hood 3 is in the connection position within the second groove. When the sample holder 4 descends to the separation position within the second groove, it can be separated by continuing to rotate in the same direction, while the stirring rod 6 remains connected to the sample holder 4 and can drive the sample holder 4 to descend to the designated position without needing to open the crucible lid 8 for any corresponding operations.

[0036] In some embodiments, both the first groove 11 and the second groove 12 extend vertically, and the tops of the first groove 11 and the second groove 12 are flush, while the bottom of the second groove 12 is below the bottom of the first groove 11. Figure 1 and Figures 3-4As shown, the inner wall of the crucible is provided with a first groove 11 and a second groove 12 arranged opposite to each other. Both the first groove 11 and the second groove 12 extend vertically, with the tops of the first groove 11 and the second groove 12 flush with each other. The bottom of the second groove 12 is located below the bottom of the first groove 11. Dynamic positioning is achieved by selectively engaging the support portions on both sides of the steam hood 3 into the oppositely arranged first groove 11 or the oppositely arranged second groove 12. Specifically, the first groove 11 can be connected to the adjacent second groove 12, or they can be arranged at intervals. In one implementation, adjacent first grooves 11 and second grooves 12 are arranged at 90° intervals. The steam hood 3 is first placed in the first groove 11. After the mother liquor is homogenized and stirred, the steam hood 3 and sample holder 4 are first lifted above the first groove 11 by the stirring rod 6. Then, the stirring rod 6 drives the steam hood 3 and sample holder 4 to rotate 90° to the top of the second groove 12. Next, the stirring rod 6 drives the steam hood 3 and sample holder 4 to descend into the second groove 12. Then, at the connection position, the stirring rod 6 is rotated to make it threadedly connected to the sample holder 4. After that, the stirring rod 6 drives the steam hood 3 and sample holder 4 to continue to descend to the separation position. At this time, the bottom of the steam hood 3 is below the liquid surface. The stirring rod 6 continues to rotate in the previous rotation direction, so that the top of the steam hood 3 and the top of the sample holder 4 are threadedly separated. Finally, the stirring rod 6 drives the steam hood 3 and sample holder 4 to continue to descend to a suitable height. The stirring rod 6 drives the sample holder 4 to rotate and grow at a uniform speed, realizing pollution suppression and process consistency throughout the process, thereby improving product consistency.

[0037] In some embodiments, the bottom of the steam hood 3 is provided with an opening 33, and the bottom of the sample rack 4 is provided with a sealing plate 45 that can seal the opening 33. For example... Figure 1 As shown, when the vapor hood 3 covers the outer periphery of the sample holder 4, the sealing plate 45 at the bottom of the sample holder 4 is located below the vapor hood 3. When the sealing plate 45 presses upward against the opening 33, the bottom of the sample holder 4 is sealed with the bottom of the vapor hood 3, which can prevent the vapor and mother liquor from contacting the substrate. When the sealing plate 45 moves downward away from the opening 33, the bottom of the sample holder 4 is separated from the bottom of the vapor hood 3, and the mother liquor can contact the substrate through the space between the sample holder 4 and the vapor hood 3.

[0038] Optionally, the steam hood 3 includes a top plate 31 and an annular side plate 32, the top of the annular side plate 32 being connected to the top plate 31, and the bottom of the annular side plate 32 forming the opening 33. Figure 1 and Figures 3-4 As shown, the annular side plate 32 is fitted onto the outside of the sample holder 4, and there is a certain gap between the annular side plate 32 and the sample holder 4 to ensure smooth growth of the epitaxial material; the top of the annular side plate 32 is sealed by the top plate 31, and the bottom is open to form an opening 33. Further, as... Figure 1 and Figures 3-4As shown, two ears 35 are arranged opposite to each other on the edge of the top plate 31 as support parts. By supporting the two ears 35 in the first or second groove of the crucible, the vapor hood 3 and the sample holder 4 can be clamped at a certain height inside the crucible.

[0039] Specifically, the top plate 31 of the steam hood 3 is provided with a through hole running vertically through the top and bottom, and the inner wall of the through hole is provided with a first internal thread 34. The top of the sample holder 4 is provided with a first external thread 46. The first internal thread 34 and the first external thread 46 cooperate to form a first thread structure. The sample holder 4 is provided with a first shaft hole 47 for the stirring rod 6 to pass through. The inner wall of the lower end of the first shaft hole 47 is provided with a second internal thread 48. The bottom of the stirring rod 6 is provided with a second external thread 61 at a position above the stirring base 5. The second internal thread 48 and the second external thread 61 cooperate to form a second thread structure.

[0040] In some embodiments, the sample holder 4 includes a sample holder body 41 for fixing a substrate, an upper sample holder 43 connected to the top of the sample holder body 41, and a lower sample holder 44 connected to the bottom of the sample holder body 41. In one embodiment, the sample holder body 41 has a tetrahedral structure, with all four sides serving as substrate fixing surfaces 42. The substrate can be fixed to the substrate fixing surfaces 42 using fixing clamps. The sample holder body 41 has a first shaft hole 47, through which the upper end of the stirring rod 6 passes, and the stirring base 5 is located below the sample holder 4. The outer side wall of the upper sample holder 43 has a first external thread 46, and the inner side wall of the lower sample holder 44 has a second internal thread 48. Screw holes 49 for installing fixing clamps are also provided on the upper sample holder 43 and the lower sample holder 44 near the sample holder body 41.

[0041] In some embodiments, the crucible includes an outer crucible 1 and an inner crucible 2 for holding the mother liquor. The inner crucible 2 is made of boron nitride or glassy carbon, while the outer crucible 1 is made of graphite. The outer surfaces of the sample holder 4 and the vapor hood 3 are coated with a glassy carbon coating. Since the outer crucible 1 is made of graphite and the inner crucible 2 is made of boron nitride or glassy carbon, placing the growth mother liquor in the inner crucible 2 effectively prevents the molten mother liquor from contacting the graphite outer crucible 1, thus reducing the introduction of graphite particles from the mother liquor at the source. The sample holder 4 and the vapor hood 3 are made of graphite, and by coating their surfaces with a glassy carbon coating, an inert barrier is formed, reducing carbon shedding from the graphite boat. Furthermore, the surface of the stirring base 5 is coated with a glassy carbon coating to reduce carbon shedding from the graphite boat; the stirring rod 6 is made of carbon or carbon fiber composite material, which improves its load-bearing and torsional mechanical properties.

[0042] Furthermore, both the first groove 11 and the second groove 12 are disposed on the inner wall of the outer crucible 1. For example... Figure 1 As shown, the outer wall of the inner crucible 2 is adapted to the inner wall of the bottom of the outer crucible 1. The inner sidewall of the outer crucible 1 at the first groove 11 and the second groove 12 is flush with the inner sidewall above the first groove 11 and the second groove 12, which facilitates the placement of the steam hood 3 into the first groove and its movement from the first groove into the second groove.

[0043] Optionally, the vertical liquid phase epitaxial graphite boat of this embodiment also includes a crucible cover 8, which is detachably connected to the top of the crucible. Further, the crucible cover 8 is provided with a second shaft hole 82 for the stirring rod 6 to pass through, and the upper end of the stirring rod 6 sequentially passes through the first shaft hole 47 and the second shaft hole 82. The crucible cover 8 can be detachably connected to the top of the outer crucible 1 by threads, by snap-fit, or by other means. After the sample holder 4 and the vapor hood 3 are installed in the crucible using the stirring rod 6 and the stirring base 5, the crucible cover 8 is placed on top of the crucible.

[0044] Preferably, the crucible lid 8 is detachably connected to the top of the outer crucible 1 via a thread. A third external thread 13 is provided on the outer side wall of the top wall of the outer crucible 1, and a third internal thread 81 is provided on the inner side wall of the bottom of the crucible lid 8. The third external thread 13 and the third internal thread 81 are compatible. After the crucible lid 8 is fitted onto the stirring rod 6, it can be screwed on to connect to the outer crucible 1, preventing contamination of the mother liquor.

[0045] This embodiment also provides a vertical liquid phase epitaxial growth apparatus, including the vertical liquid phase epitaxial graphite boat described in any of the above embodiments.

[0046] In some embodiments, the vertical liquid phase epitaxial growth apparatus further includes a transmission device for driving the stirring rod 6 to rotate and move up and down, with the top of the stirring rod 6 connected to the transmission shaft of the transmission device. Specifically, the transmission device includes a lifting mechanism for driving the stirring rod 6 to move up and down and a rotating mechanism for driving the stirring rod 6 to rotate 360° in both directions. The rotating mechanism is connected to the output end of the lifting mechanism, and the output end of the rotating device is connected to the top of the stirring rod 6 via the transmission shaft. The fourth external thread 62 on the top of the stirring rod 6 can be threadedly connected to the transmission shaft.

[0047] This embodiment also provides a vertical liquid phase epitaxial growth method, which uses the vertical liquid phase epitaxial growth apparatus described above, and the method includes the following process;

[0048] During the high-temperature homogenization process of the mother liquor, the vapor hood 3 is located in the first groove, and the vapor hood 3 and the sample holder 4 enclose a sealed cavity, with the substrate located inside the sealed cavity.

[0049] During the epitaxial growth process, the vapor hood 3 is located in the second groove. The vapor hood 3 and the sample holder 4 are gradually lowered together until the vapor hood 3 is in the separation position. At this time, the bottom of the vapor hood 3 is lowered below the mother liquor surface. The sample holder 4 is then separated from the vapor hood 3, and epitaxial growth is carried out.

[0050] In the process of high-temperature homogenization of the mother liquor and the process of the substrate descending to the mother liquor before growth, this utility model uses a steam hood 3 to completely wrap the sample holder 4, physically isolating the substrate from mercury vapor and suspended graphite particles in the mother liquor, thereby reducing surface defects of the epitaxial material, improving the quality of the epitaxial material and the product yield, and achieving pollution suppression and process consistency throughout the process, resulting in high product consistency.

[0051] Furthermore, during the high-temperature homogenization of the mother liquor, the stirring rod 6 is separated from the sample holder 4; during the epitaxial growth process, the stirring rod 6 is connected to the sample holder 4.

[0052] In some embodiments, the vertical liquid phase epitaxial growth method further includes a graphite boat assembly process, specifically: before the mother liquor high-temperature homogenization process, the substrate is first mounted on the sample holder 4, then the vapor hood 3 is fitted onto the sample holder 4, and the top of the sample holder 4 is detachably connected to the top of the vapor hood 3. At the same time, the sealing plate 45 at the bottom of the sample holder 4 seals the opening 33 at the bottom of the vapor hood 3. Then, the stirring rod 6 is reliably connected to the stirring base 5, and the stirring rod 6 is fitted into the sample holder 4. Subsequently, the vapor hood 3 and the sample holder 4 are placed in the crucible through the stirring rod 6 and the stirring base 5. Finally, the outer crucible 1 cover is passed through the stirring rod 6 and screwed tightly to the upper end of the outer crucible 1.

[0053] Preferably, a graphite boat pretreatment process is included before the graphite boat assembly process. Specifically, each component of the graphite boat is first ground and polished sequentially. Then, the ground and polished components are cleaned and dried. After that, the dried components are subjected to high-temperature degassing in a reducing protective gas atmosphere. Grinding removes traces left from the machining process of the graphite boat components. Polishing improves the surface smoothness of the graphite boat components. Cleaning removes carbon particles and various impurities embedded on the surface of the graphite boat. High-temperature degassing removes residual water molecules and free graphite particles from the surface of the graphite boat components, preventing these impurities from adversely affecting the film quality during subsequent epitaxial growth and ensuring the stability of the graphite boat for repeated use.

[0054] Furthermore, the polished components undergo a cleaning process, including the following steps: First, the polished graphite boat components are ultrasonically cleaned in water until no obvious floating carbon particles are precipitated in the cleaning water. Then, the ultrasonically cleaned graphite boat components are sequentially cleaned for oil stains and metal ions. Finally, the graphite boat components are repeatedly boiled and cleaned with deionized water. This multi-stage cleaning process thoroughly removes embedded carbon particles.

[0055] The method of this utility model will be described in detail below through a specific embodiment.

[0056] A vertical liquid phase epitaxial growth method for a mercury cadmium telluride single crystal thin film, using the aforementioned vertical liquid phase epitaxial graphite boat, includes the following steps:

[0057] S1. Preparation steps for graphite boat

[0058] S1-1 Grinding and Polishing Treatment: Metallographic sandpaper is used to grind each component of the graphite boat to remove traces left from the machining process. During grinding, it is necessary to ensure that the diameter of the stirring rod 6 is 0.5-1mm smaller than the diameter of the first shaft hole 47 of the sample holder 4 to reduce the friction between the two during relative movement. After the initial grinding, in order to further improve the surface finish of each component of the graphite boat, metallographic sandpaper with a higher grit is used to polish each component of the graphite boat until the surface of each component of the graphite boat is bright, laying a good foundation for subsequent cleaning and use.

[0059] S1-2 Cleaning Process: After grinding and polishing, all parts of the graphite boat are placed in water for ultrasonic cleaning. The high-frequency vibration of the ultrasonic waves effectively removes carbon particles embedded in the surface of the graphite boat until no obvious floating carbon particles are precipitated in the cleaning water. After ultrasonic cleaning, oil stain cleaning and metal ion cleaning are performed in sequence to remove various impurities. Finally, the graphite boat is repeatedly boiled and cleaned with deionized water to ensure that residual impurities are thoroughly cleaned. Through multi-stage cleaning, embedded carbon particles are thoroughly removed. Then, drying is performed to ensure that all parts of the graphite boat are dry and clean.

[0060] S1-3 Degassing Treatment: After cleaning and drying, all components of the graphite boat are placed in a high-temperature degassing furnace. High-temperature degassing is carried out under a reducing protective gas atmosphere. The high temperature removes residual water molecules and free graphite particles from the surface of each component of the graphite boat, preventing these impurities from adversely affecting the quality of the film during subsequent epitaxial growth and ensuring that the graphite boat can stably and reliably participate in subsequent processes.

[0061] S2 Graphite Boat Assembly and Sample Loading Steps

[0062] S2-1 Substrate mounting: Use clamps to precisely fix the cleaned substrate onto sample holder 4, ensuring that the substrate is flat and firmly installed in the designated position, providing a stable substrate for subsequent epitaxial growth;

[0063] S2-2 Graphite Boat Assembly: First, the vapor hood 3 is fitted onto the sample holder 4. The first external thread 46 on the top of the sample holder 4 is screwed onto the first internal thread 34 on the top of the vapor hood 3. At the same time, the sealing plate 45 at the bottom of the sample holder 4 seals the open opening 33 at the bottom of the vapor hood 3, achieving a sealed fit between the two. Then, the stirring rod 6 is reliably connected to the stirring base 5 with screws, and the stirring rod 6 is fitted into the first shaft hole 47 of the sample holder 4. Subsequently, the vapor hood 3, along with the sample holder 4, is placed in the outer crucible 1 through the stirring rod 6 and the stirring base 5, and the first groove 11 on the side wall of the outer crucible 1 is used to support and position the vapor hood 3. Finally, the mother liquor is added to the inner crucible 2, and the second shaft hole 82 of the outer crucible 1 is passed through the stirring rod 6 and screwed onto the upper end of the outer crucible 1 to complete the overall assembly of the graphite boat. This ensures that all components are tightly connected and accurately positioned to guarantee the smooth progress of the subsequent epitaxial process.

[0064] S3 Epitaxial Growth Steps

[0065] S3-1 High-Temperature Homogenization of Mother Solution: Before starting epitaxial growth, the mother solution needs to be homogenized at high temperature. The assembled graphite boat is placed in the corresponding position of the liquid phase epitaxy equipment, so that the sample holder 4 and the stirring base 5 are separated. The sample holder 4 is located above the mother solution, while the bottom of the stirring rod 6 and the stirring base 5 extend into the mother solution. The stirring rod 6 and the stirring base 5 are rotated and stirred by the drive shaft of the epitaxy equipment to fully homogenize the mother solution and ensure that the components in the mother solution are evenly distributed, providing a uniform growth environment for epitaxial growth.

[0066] S3-2 Substrate Descending to Mother Solution Before Growth: When the mother solution temperature drops to 1-2°C before the epitaxial growth temperature, start the equipment drive shaft to simultaneously lift the sample holder 4 and the vapor hood 3, causing the side ears of the vapor hood 3 to disengage from the constraint of the first groove 11 on the inner wall of the outer crucible 1. Then, the drive shaft rotates the sample holder 4 and the vapor hood 3 90°, so that the side ears of the vapor hood 3 are precisely aligned with the position of the second groove 12 on the inner wall of the outer crucible 1. Subsequently, the drive shaft slowly lowers the sample holder 4 and the vapor hood 3 to the set connection position, and rotates clockwise to connect the sample holder 4 and the stirring base 5. During this process, the vapor hood 3 always completely covers the sample holder 4 and the substrate, ensuring that the substrate surface does not come into contact with the mother liquor surface, effectively preventing graphite particles suspended on the mother liquor surface from adhering to the substrate surface and forming defects; when it descends to the separation position, the bottom of the vapor hood 3 is below the mother liquor surface, and the drive shaft drives the sample holder 4 to rotate clockwise according to the preset number of turns (set according to the thread length), completing the separation action between the vapor hood 3 and the sample holder 4. Then the drive shaft continues to drive the sample holder 4 to descend to the specific position for epitaxial growth, ready to start epitaxial growth;

[0067] S3-3 Epitaxial Growth: During the loading of the graphite boat into the furnace, the upper end of the stirring rod 6 is reliably connected to the drive shaft of the epitaxial equipment. At this time, the drive shaft has the ability to drive the stirring rod 6 to achieve up-and-down movement and rotation. The drive shaft drives the sample holder 4 to descend to the appropriate growth position according to the preset program, and starts the epitaxial growth process. During the growth process, the sample holder 4 is kept rotating at a constant speed to ensure the uniformity of the epitaxial film growth. When the set end temperature is reached, the sample holder 4 with the substrate is lifted by the drive shaft to terminate the epitaxial growth process and complete the epitaxial growth task of this cycle.

[0068] S3-4 Graphite Boat Cleaning and Degassing: After epitaxial growth is completed, carefully remove the epitaxial wafer. At this time, a small amount of mother liquor residue may remain on the surface of the stirring rod 6 and sample holder 4. Use a high-temperature degassing method to remove the mother liquor adhering to the surface of the sample holder 4 and stirring rod 6. After the degassing process is completed, use lint-free paper or lint-free cloth to thoroughly wipe the surface of each component of the graphite boat, and then use a nitrogen pressure gun to blow away the surface of the graphite boat to completely remove residual mother liquor powder and floating carbon and other impurities, in order to prepare for the next round of epitaxial growth and ensure the cleanliness and performance stability of the graphite boat.

[0069] This embodiment, through the orderly implementation of each step, can improve the quality of epitaxial materials, reduce defect density, and increase product yield, demonstrating significant practical value and promising prospects for widespread application.

[0070] Figure 7 and Figure 9 These are interface and surface images of liquid phase epitaxial materials prepared using existing unmodified graphite boats and methods after substrate removal. Figure 8 and Figure 10The images show the interface and surface of the liquid-phase epitaxial material prepared using the graphite boat and method of this embodiment after substrate removal. (Comparison) Figure 7 and Figure 8 It can be seen that the material interface prepared using the unmodified graphite boat has a large amount of black carbon material adhering to it, which seriously affects product quality and leads to a decrease in production yield and efficiency. In contrast, the epitaxial material interface prepared using the graphite boat and method of this invention is clean and free of carbon material adhering to it. Figure 9 and Figure 10 It can be seen that the surface of the material prepared using the unmodified graphite boat has a large amount of black carbon material adhering to it, while the surface of the epitaxial material prepared using the graphite boat and method of this invention is clean and free of carbon material. Therefore, the graphite boat and method of this invention can achieve a carbon-free surface on the epitaxial material, effectively eliminating substrate interface contamination defects at the source. Thus, it is highly effective in reducing carbon contamination defects and improving the quality of epitaxial materials, providing reliable technical support for the high-quality, mass production of mercury cadmium telluride single crystal thin films.

[0071] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A vertical liquid phase epitaxial graphite boat, comprising a crucible, wherein a sample holder is disposed within the crucible, characterized in that: The crucible is further provided with a vapor hood, which covers the outer periphery of the sample holder. The crucible is provided with a first groove for limiting the vapor hood during the homogenization of the mother liquor and a second groove for limiting the vapor hood during epitaxial growth. A separation position is provided in the second groove. The vapor hood can move up and down and switch between the first groove and the second groove. When the vapor hood is in the separation position or below, its bottom is below the surface of the mother liquor. The vapor hood can connect with the sample holder and form a sealing cavity for sealing the substrate when it is above the separation position in the first groove and the second groove, and can separate from the sample holder when it is in the separation position in the second groove or below.

2. The vertical liquid phase epitaxial graphite boat as described in claim 1, characterized in that: The crucible is also equipped with a stirring base, and a stirring rod is connected to the stirring base. The sample holder is sleeved on the stirring rod.

3. The vertical liquid-phase epitaxial graphite boat as described in claim 2, characterized in that: The second groove also has a connection position located above the separation position; the stirring rod is detachably connected to the bottom of the sample holder, and the stirring rod can be separated from the sample holder when the steam hood is located in the first groove and connected to the sample holder when the steam hood is located at or below the connection position in the second groove.

4. The vertical liquid phase epitaxial graphite boat as described in claim 3, characterized in that: The top of the sample holder is detachably connected to the top of the steam hood via a first threaded structure, and the bottom of the sample holder is detachably connected to the stirring rod via a second threaded structure. The first threaded structure and the second threaded structure have opposite thread directions.

5. The vertical liquid-phase epitaxial graphite boat as described in claim 1, characterized in that: Both the first groove and the second groove extend vertically, with the top of the first groove and the top of the second groove being flush, and the bottom of the second groove being below the bottom of the first groove.

6. The vertical liquid-phase epitaxial graphite boat as described in claim 1, characterized in that: The bottom of the steam hood is provided with an opening, and the bottom of the sample rack is provided with a sealing plate that can seal the opening.

7. The vertical liquid-phase epitaxial graphite boat as described in claim 6, characterized in that: The steam hood includes a top plate and an annular side plate, the top of which is connected to the top plate, and the bottom of which forms the opening.

8. The vertical liquid-phase epitaxial graphite boat as described in claim 1, characterized in that: The crucible includes an outer crucible and an inner crucible for holding the mother liquor. The inner crucible is made of boron nitride or glassy carbon material, and the outer crucible is made of graphite material. The sample holder and the outer surface of the vapor hood are coated with glassy carbon coating.

9. The vertical liquid-phase epitaxial graphite boat as described in claim 1, characterized in that: It also includes a crucible lid, which is detachably connected to the top of the crucible.

10. A vertical liquid phase epitaxial growth apparatus, characterized in that: Includes the vertical liquid phase epitaxial graphite boat according to any one of claims 1-9.

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