Vertical liquid phase epitaxy graphite tool, growth device and growth method

Abstract

The invention provides a vertical liquid phase epitaxy graphite tool, a growth device and a growth method.The graphite tool comprises a sample frame, a stirring rod and a stirring base, the stirring rod is sleeved with the sample frame, and the stirring base is connected with the end of the stirring rod; the stirring base can move up and down relative to the sample frame and is provided with a floating carbon removing position and a stirring position located below the floating carbon removing position, and when the stirring base moves to the floating carbon removing position, a cavity used for containing floating carbon on the surface of mother liquor is defined by the stirring base and the sample frame. Through the separation design of the sample rack and the stirring device, the sample rack with the substrate is prevented from entering the mother liquor in the high-temperature homogenization stirring process of the mother liquor, so that the condition that the surface layer of the substrate is melted in the mother liquor at high temperature to cause the change of mother liquor components is avoided; meanwhile, by utilizing the structural design that the lower part of the sample holder and the stirring base form a cavity to remove floating carbon, the floating carbon on the surface of mother liquor in the growth stage can be effectively reduced, so that the carbon contamination defect on the epitaxial surface is reduced, and the yield of epitaxial materials is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid phase epitaxial growth of thin film materials, and in particular relates to a vertical liquid phase epitaxial graphite tooling, a growth device and a growth method. Background Art

[0002] Liquid phase epitaxy is currently the most mature method for preparing HgCdTe single crystal thin films. The tellurium-rich vertical liquid phase epitaxial growth technology uses a "semi-infinite mother liquid" growth method, so that compared with horizontal epitaxy, the grown epitaxial surface does not have macroscopic ripples, and the prepared detector imaging does not have "shading" and "ghosting" phenomena. At the same time, compared with the horizontal epitaxial growth method, the production capacity can be increased by at least 2 to 4 times, and the HgCdTe mother liquid can be reused for hundreds of rounds, greatly reducing the process cost.

[0003] Liquid phase epitaxy uses a solid-liquid phase transition growth method. The uniformity and cleanliness of the mother liquid directly determine the thickness, composition and defect density of the epitaxial single crystal film. During cooling, the components of the mercury-cadmium-telluride ternary alloy will condense, which will lead to poor uniformity of the mother liquid. Therefore, before each round of growth, the mother liquid needs to be heated to 30-50°C above the crystallization point, and the mother liquid needs to be fully stirred and homogenized.

[0004] At present, for the tooling for stirring and homogenizing the mother liquor, the stirring rod and the sample holder are generally integrated, or the stirring rod and the sample holder are separated. For the structural design of the stirring rod and the sample holder integrated, when the mother liquor is homogenized, the substrate must be brought into the mother liquor. However, the high temperature of the mother liquor will cause the substrate to melt back into the mother liquor, which will cause the mother liquor composition to change, seriously affecting the control of the consistency of the thickness of the epitaxial film; at the same time, the substrate melting will cause the surface flatness of the substrate to decrease, further affecting the surface flatness of the epitaxial surface. For the structural design of the separation of the stirring rod and the sample holder, due to the good mechanical processing and chemical stability of graphite, graphite is basically used in the field of complex structural parts processing with high purity requirements. During the motion stirring, there is mutual friction between the graphite tooling, resulting in carbon falling. The carbon that falls will float on the surface of the mother liquor because its density is smaller than that of the mercury cadmium telluride mother liquor. When the substrate descends and grows, the carbon that falls will stick to the surface of the substrate, resulting in epitaxial growth defects, which seriously affects the process yield. Summary of the invention

[0005] The purpose of the present invention is to provide a vertical liquid phase epitaxial graphite tooling, which can at least solve some of the defects existing in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A vertical liquid phase epitaxial graphite tooling comprises a sample holder, a stirring rod and a stirring base, wherein the sample holder is sleeved on the stirring rod, the stirring base is connected to the end of the stirring rod, the stirring base can move up and down relative to the sample holder and has a floating carbon removal position and a stirring position located below the floating carbon removal position, and when the stirring base moves to the floating carbon removal position, it and the sample holder are combined to form a cavity for loading floating carbon on the surface of a mother liquid.

[0008] Furthermore, the stirring base includes a connecting portion for connecting to the bottom of the stirring rod, an annular side wall coaxially arranged with the connecting portion, and a bottom plate connected between the annular side wall and the connecting portion; the annular side wall, the connecting portion and the bottom plate constitute an annular groove structure.

[0009] Furthermore, an opening is provided at the lower portion of the annular side wall for the mother liquid to overflow, and when the stirring base moves to enclose the sample holder to form a cavity, the sample holder closes the opening.

[0010] Furthermore, the sample holder includes a cylindrical barrel section and an expanded diameter barrel section, the cylindrical barrel section is detachably connected to the stirring rod, the small diameter end of the expanded diameter barrel section is connected to the bottom of the cylindrical barrel section, and a cavity area with an opening at the lower end is formed inside the expanded diameter barrel section. When the stirring base moves to the floating carbon removal position, it is connected to the expanded diameter barrel section to close the lower end opening of the cavity area.

[0011] Furthermore, a sleeve is sleeved on the lower part of the stirring rod, a side wall of the sleeve is located between the sample holder and the stirring rod, and a bottom wall of the sleeve is located between the stirring rod and the stirring base.

[0012] Furthermore, the vertical liquid phase epitaxial graphite tooling further includes a sample rack cover, which is sleeved on the sample rack and detachably connected to the top of the sample rack.

[0013] Furthermore, the sample holder cover is detachably connected to the sample holder via a first thread structure, and the sample holder is detachably connected to the stirring rod via a second thread structure, and the thread directions of the first thread structure and the second thread structure are opposite.

[0014] Furthermore, the stirring rod is made of carbon or SiC fiber composite material; the sample holder and the stirring base are made of graphite, and the outer surfaces thereof are coated with SiC coating.

[0015] In addition, the present invention also provides a vertical liquid phase epitaxial growth device, including the above-mentioned vertical liquid phase epitaxial graphite tooling, and a growth container for containing mother liquid.

[0016] The present invention also provides a vertical liquid phase epitaxial growth method, comprising the following process:

[0017] During the high-temperature homogenization of the mother liquid, the sample holder is separated from the stirring base, and the lower part of the sample holder is at least partially located in the mother liquid, and the stirring base is located in the mother liquid to stir the mother liquid homogenously;

[0018] After the mother liquor is homogenized, the stirring rod is lifted to connect the stirring base with the lower part of the sample rack, and the surface floating carbon mother liquor is collected by using the cavity formed by the sample rack and the stirring base;

[0019] After the floating carbon mother liquor is collected, the sample holder is lowered together with the stirring base and placed in the mother liquor for epitaxial growth.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The vertical liquid phase epitaxial graphite tooling provided by the present invention prevents the sample holder with the substrate from entering the mother liquid during the stirring process of the mother liquid being homogenized at high temperature, thereby preventing the surface layer of the substrate from melting in the mother liquid at high temperature, causing a change in the composition of the mother liquid; at the same time, by utilizing the structure design of forming a cavity with the lower part of the sample holder and the stirring base to remove floating carbon, the floating carbon on the surface of the mercury cadmium telluride mother liquid during the growth stage can be effectively reduced, thereby reducing the carbon contamination defects on the epitaxial surface and improving the yield of the epitaxial material.

[0022] The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the cross-sectional structure of the vertical liquid phase epitaxial graphite tooling of the present invention;

[0024] Figure 2 It is a schematic diagram of the vertical liquid phase epitaxial growth process of the present invention;

[0025] Figure 3 It is a schematic diagram of the process of rotating the stirring base to load and take the surface floating carbon mother liquid in the present invention;

[0026] Figure 4 This is a microscopic image of the epitaxial growth material that has not been prepared with improvement;

[0027] Figure 5 This is a microscopic examination image of an epitaxially grown material prepared by using the vertical liquid phase epitaxial graphite tooling of the present invention.

[0028] Explanation of the reference numerals: 1. sample holder cover; 2. stirring rod; 3. sample holder; 4. cavity; 5. sleeve; 6. stirring base; 7. stirring rod screw; 8. growth container; 31. cylindrical barrel section; 32. expanded diameter barrel section; 61. connecting portion; 62. annular groove; 63. annular side wall; 64. bottom plate; 65. opening. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0033] like Figure 1 and Figure 2 As shown, this embodiment provides a vertical liquid phase epitaxial graphite tooling, including a sample holder 3, a stirring rod 2 and a stirring base 6, wherein the sample holder 3 is sleeved on the stirring rod 2, and the stirring base 6 is connected to the end of the stirring rod 2, and the stirring base 6 can move up and down relative to the sample holder 3 and has a floating carbon removal position and a stirring position located below the floating carbon removal position, and when the stirring base 6 moves to the floating carbon removal position, it and the sample holder 3 enclose a cavity 4 for loading floating carbon on the surface of the mother liquid.

[0034] Based on the vertical liquid phase epitaxial graphite tooling of this embodiment, this embodiment also provides a vertical liquid phase epitaxial growth device, including the vertical liquid phase epitaxial graphite tooling of the above embodiment, and a growth container 8 for containing the mother liquid; wherein the growth container 8 can be a crucible but is not limited to it.

[0035] When performing liquid phase epitaxial growth, the mother liquid is placed in a growth container 8, and the vertical liquid phase epitaxial graphite process of this embodiment is arranged above the container. During the high-temperature homogenization process of the mother liquid, the sample holder 3 is separated from the stirring base 6, and the lower part of the sample holder 3 is at least partially located in the mother liquid, and the stirring base 6 is located in the mother liquid. The up and down movement of the stirring base 6 can stir the mother liquid uniformly; after the mother liquid is homogenized and before the epitaxial growth, the stirring rod 2 is lifted to connect the stirring base 6 with the lower part of the sample holder 3, and the floating carbon on the surface of the mother liquid is loaded into the cavity 4 formed by the sample holder 3 and the stirring base 6 to prevent the epitaxial growth substrate from descending through the surface of the mother liquid to form carbon contamination defects; after the floating carbon mother liquid is collected, the sample holder 3 is lowered together with the stirring base 6 and placed in the mother liquid for epitaxial growth. In this embodiment, the sample holder 3 and the stirring device are separated to prevent the sample holder 3 with the substrate from entering the mother liquid during the stirring process of the mother liquid being homogenized at high temperature, thereby preventing the surface layer of the substrate from melting in the mother liquid at high temperature and causing changes in the composition of the mother liquid. At the same time, the structure design of using the lower part of the sample holder 3 and the stirring base 6 to form a cavity 4 to remove floating carbon can effectively reduce the floating carbon on the surface of the mercury cadmium telluride mother liquid during the growth stage, thereby reducing the carbon contamination defects on the epitaxial surface and improving the yield of the epitaxial material.

[0036] Preferably, the stirring rod 2 is made of carbon or SiC fiber composite material to improve load-bearing and anti-torsion mechanical properties. The sample holder 3 and the stirring base 6 are made of graphite material, and the outer surface thereof is coated with SiC coating, which can reduce carbon loss, thereby effectively reducing floating carbon on the surface of mercury cadmium telluride mother solution during the growth stage.

[0037] As a specific implementation method, Figure 1As shown, the stirring base 6 includes a connecting portion 61 for connecting to the bottom of the stirring rod 2, an annular side wall 63 coaxially arranged with the connecting portion 61, and a bottom plate 64 connected between the annular side wall 63 and the connecting portion 61; the annular side wall, the connecting portion 61 and the bottom plate 64 constitute an annular groove 62 structure; the stirring base 6 adopts a structural design with an annular groove 62, which can better load the surface floating carbon mother liquid. Specifically, the center of the connecting portion 61 of the stirring base 6 has a screw hole 1 passing through, and the bottom of the stirring rod 2 has a screw hole 2 corresponding to the screw hole 1 on the connecting portion 61, and the screw hole 1 and the screw hole 2 are connected by the stirring rod screw 7, so that the stirring base 6 is fixed to the stirring rod 2; at the same time, when the stirring base 6 is in the floating carbon removal position, its annular side wall 63 is threadedly connected to the inner side wall of the lower part of the sample holder 3, so that the annular groove 62 of the stirring base 6 and the lower part of the sample holder 3 enclose a cavity 4.

[0038] Further, such as Figure 3 As shown, an opening 65 for the mother liquid to overflow is provided at the lower part of the annular side wall 63, and the opening 65 is arranged circumferentially along the annular side wall 63; through the structural design of the opening 65, when the stirring base 6 rises and rotates to seal the floating carbon mother liquid, the bottom mother liquid can preferentially overflow from the opening 65, without affecting the floating state of the surface floating carbon, which is conducive to better collecting the surface floating carbon mother liquid; at the same time, the opening 65 is designed at the lower part of the annular side wall 63, when the stirring base 6 moves to enclose the sample holder 3 to form the cavity 4, the sample holder 3 can be used to close the opening 65, thereby not affecting the subsequent epitaxial growth process.

[0039] As a specific implementation method, Figure 1 As shown, the sample holder 3 includes a cylindrical barrel section 31 and an expanded diameter barrel section 32, the cylindrical barrel section 31 is detachably connected to the stirring rod 2, the small diameter end of the expanded diameter barrel section 32 is connected to the bottom of the cylindrical barrel section 31, and a cavity area with an opening at the lower end is formed inside the expanded diameter barrel section 32. When the stirring base 6 moves to the floating carbon removal position, it is connected to the expanded diameter barrel section 32 to close the lower end opening of the cavity area to form a cavity 4. Specifically, the cylindrical barrel section 31 of the sample holder 3 is threadedly connected to the stirring rod 2, and the expanded diameter barrel section 32 of the sample holder 3 is threadedly connected to the outer wall of the annular groove 62 of the stirring base 6, and the space enclosed by the expanded diameter barrel section 32, the stirring rod 2, and the annular groove 62 of the stirring base 6 constitutes the cavity 4.

[0040] Optimally, a sleeve 5 is mounted on the lower part of the stirring rod 2, the side wall of the sleeve 5 is located between the sample holder 3 and the stirring rod 2, the bottom wall of the sleeve 5 is located between the stirring rod 2 and the stirring base 6, and a screw hole is also provided at the bottom center of the sleeve 5, and the stirring base 6, the sleeve 5 and the stirring rod 2 are fixed by the stirring rod screw 7; the design of the sleeve 5 can effectively prevent carbon loss caused by the friction between the sample holder 3 and the stirring rod 2. Specifically, the material of the sleeve 5 can be selected but not limited to quartz.

[0041] Optionally, the vertical liquid phase epitaxial graphite tooling of this embodiment further includes a sample holder outer cover 1, the top center of the sample holder outer cover 1 is provided with a center hole for the upper end of the stirring rod 2 to pass through, the sample holder outer cover 1 is sleeved on the sample holder 3, and is detachably connected to the top of the sample holder 3, the lower end of the center hole of the sample holder outer cover 2 is detachably connected to the upper end of the sample holder 3 by, but not limited to, a thread, and can also be detachably connected by other means, including, but not limited to, snap-on connection, etc. When performing liquid phase epitaxial growth, the sample holder outer cover 1 can be covered on the upper opening of the growth container 8.

[0042] Preferably, the sample rack cover 1 and the sample rack 3 are detachably connected via a first threaded structure, and the sample rack 3 and the stirring rod 2 are detachably connected via a second threaded structure, and the thread directions of the first threaded structure and the second threaded structure are opposite; the connection arrangement among the sample rack 3, the stirring rod 2 and the sample rack cover 1 only requires rotating the stirring rod 2 in different directions outside the sample rack cover 1 to achieve connection and separation of the sample rack 3 and the stirring base 6, without the need to open the sample rack cover 1 for corresponding operations.

[0043] The following specifically describes the operation process of vertical liquid phase epitaxial growth using the vertical liquid phase epitaxial growth device of this embodiment, which specifically includes the following steps:

[0044] S1: Assembling epitaxial graphite tooling and loading substrate. Install the sleeve 5 and the stirring base 6 on the bottom of the stirring rod 2 in sequence, and fix the three with the stirring rod screw 7; fix the cleaned substrate on the sample holder 3 with a clamp, put the sample holder cover 1 on the outside of the sample holder 3 and tighten the threads; finally, put the sample holder 3 on the stirring rod 2 and tighten the connecting threads of the two.

[0045] S2: Preparation of mother liquid. Calculate the appropriate amount of mother liquid according to formula 1 so that the liquid level is just about halfway to the cavity 4 of the sample holder 3; weigh the amount of mother liquid required for calculation and put the mother liquid into the crucible.

[0046]

[0047] In formula 1, h1 is the height of the sample holder, h2 is the height of the bottom cavity of the sample holder, h3 is the height of the crucible, r is the radius of the crucible, V 底座 is the volume of the stirring base, ρ 母液 is the density of the mother solution.

[0048] S3: homogenizing the mother liquid. The upper end of the stirring rod 2 is connected to the transmission shaft of the epitaxial device, and the transmission shaft can realize up and down movement and rotation; the epitaxial furnace is heated to the homogenization temperature to melt the mother liquid, the stirring rod 2 and the sample holder 3 are loosened, and the sample holder 3 is separated from the stirring base 6, and the stirring base 6 is located in the mother liquid and moves up and down to fully stir the mother liquid.

[0049] S4: Load the floating carbon mother solution before growth. Cool down to the growth temperature, slowly raise the stirring rod 2, so that the internal thread of the sample holder 3 contacts the external thread of the stirring base 6, such as Figure 3 (a); Then slowly rotate the stirring rod 2 to tighten the sample holder 3 and the stirring base 6, and the mother liquor with floating carbon is loaded into the cavity 4 formed by the bottom of the sample holder 3 and the stirring base 6. The opening 63 at the bottom of the stirring base 6 makes the stirring base 6 rise and rotate to seal the floating carbon mother liquor, and the bottom mother liquor overflows first. The floating carbon mother liquor is collected. Figure 3 (b).

[0050] S5: Epitaxial growth. After the sample holder 3 and the stirring base 6 are screwed together, the stirring rod 2 is rotated continuously to loosen the threads of the sample holder 3 and the sample holder cover 1, and the sample holder 3 is lowered together with the stirring base 6 to perform epitaxial growth.

[0051] S6: Growth ends. After reaching the end temperature, lift the sample rack 3 to quench the mother liquid; after the mother liquid cools to room temperature, weigh the mother liquid with floating carbon, and add the same weight of mother liquid to the mother liquid for the next round of growth.

[0052] The liquid phase epitaxial materials prepared by the graphite boat in the prior art and the vertical liquid phase epitaxial graphite tooling provided by the present invention were examined under a microscope, and the results are as follows: Figure 4 and Figure 5 As shown. Figure 4 It can be seen that the surface of the prepared epitaxial material is obviously attached with black carbon material, which leads to a decrease in the yield and production efficiency during the production process. Figure 4 It can be seen that the surface of the epitaxial material prepared by the vertical liquid phase epitaxial graphite tooling of the present invention is clean and has no carbon material attached; this shows that the vertical liquid phase epitaxial graphite tooling designed by the present invention and the epitaxial material obtained by vertical liquid phase epitaxial growth using the graphite tooling overcome the defects existing in the prior art and significantly improve the quality and production efficiency of the epitaxial material.

[0053] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A vertical liquid phase epitaxial graphite tooling, characterized in that: The invention comprises a sample rack, a stirring rod and a stirring base, wherein the sample rack is sleeved on the stirring rod, the stirring base is connected to the end of the stirring rod, the stirring base can move up and down relative to the sample rack and has a floating carbon removal position and a stirring position located below the floating carbon removal position, and when the stirring base moves to the floating carbon removal position, it and the sample rack are combined to form a cavity for loading floating carbon on the surface of the mother liquid.

2. The vertical liquid phase epitaxial graphite tooling according to claim 1, characterized in that: The stirring base includes a connecting portion for connecting to the bottom of the stirring rod, an annular side wall coaxially arranged with the connecting portion, and a bottom plate connected between the annular side wall and the connecting portion; the annular side wall, the connecting portion and the bottom plate constitute an annular groove structure.

3. The vertical liquid phase epitaxial graphite tooling as claimed in claim 2, characterized in that: An opening for the mother liquid to overflow is provided at the lower part of the annular side wall, and when the stirring base moves to enclose with the sample holder to form a cavity, the sample holder closes the opening.

4. The vertical liquid phase epitaxial graphite tooling according to claim 1, characterized in that: The sample holder comprises a cylindrical barrel section and an expanded diameter barrel section, wherein the cylindrical barrel section is detachably connected to the stirring rod, the small diameter end of the expanded diameter barrel section is connected to the bottom of the cylindrical barrel section, a cavity area with a lower end opening is formed inside the expanded diameter barrel section, and when the stirring base moves to the floating carbon removal position, it is connected to the expanded diameter barrel section to close the lower end opening of the cavity area.

5. The vertical liquid phase epitaxial graphite tooling as claimed in claim 1, characterized in that: A sleeve is sleeved on the lower part of the stirring rod, the side wall of the sleeve is located between the sample holder and the stirring rod, and the bottom wall of the sleeve is located between the stirring rod and the stirring base.

6. The vertical liquid phase epitaxial graphite tooling according to claim 1, characterized in that: The invention also comprises a sample rack cover, which is sleeved on the sample rack and detachably connected to the top of the sample rack.

7. The vertical liquid phase epitaxial graphite tooling as claimed in claim 6, characterized in that: The sample rack cover is detachably connected to the sample rack via a first thread structure, and the sample rack is detachably connected to the stirring rod via a second thread structure, wherein the thread directions of the first thread structure and the second thread structure are opposite.

8. The vertical liquid phase epitaxial graphite tooling as claimed in claim 1, characterized in that: The stirring rod is made of carbon or SiC fiber composite material, the sample holder and the stirring base are made of graphite, and the outer surfaces thereof are coated with SiC coating.

9. A vertical liquid phase epitaxial growth device, characterized in that: The invention comprises the vertical liquid phase epitaxial graphite tooling as described in any one of claims 1 to 8, and a growth container for containing mother liquid.

10. A vertical liquid phase epitaxial growth method, characterized in that: The vertical liquid phase epitaxial growth device according to claim 9 includes the following process: During the high-temperature homogenization of the mother liquid, the sample holder is separated from the stirring base, and the lower part of the sample holder is at least partially located in the mother liquid, and the stirring base is located in the mother liquid to stir the mother liquid uniformly; After the mother liquor is homogenized, the stirring rod is lifted to connect the stirring base with the lower part of the sample rack, and the surface floating carbon mother liquor is collected by using the cavity formed by the sample rack and the stirring base; After the floating carbon mother liquor is collected, the sample holder is lowered together with the stirring base and placed in the mother liquor for epitaxial growth.

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