Graphite boat structure for liquid phase epitaxial growth and liquid phase epitaxial growth process method

Abstract

The invention provides a graphite boat structure for liquid phase epitaxial growth and a liquid phase epitaxial growth process method, and relates to the technical field of semiconductor film preparation. The graphite boat structure comprises a graphite bottom support which is provided with a mounting position for mounting a mother liquor tank; the graphite mother liquor tank is used for containing mother liquor for epitaxial growth, and the mother liquor tank is detachably connected into the mounting groove; a sliding strip is connected between the graphite mother liquor tank and the graphite bottom support in a sliding manner, and the sliding strip is used for bearing a substrate and selectively slides to the position under the graphite mother liquor tank for epitaxial growth; the heat-resistant medium module is configured to be selectively nested on the outer side of a mother liquor accommodating part of the graphite mother liquor tank to form a structure that a growth area is coated with a heat-resistant medium; wherein the heat conductivity coefficient of the heat-resistant medium module is lower than that of the graphite bottom support and that of the graphite mother liquor tank. According to the process method, the graphite boat structure is adopted for liquid-phase epitaxial growth. According to the invention, the fringe effect of the tellurium-cadmium-mercury material of tellurium-rich liquid phase epitaxy can be effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of semiconductor thin film preparation technology, and in particular to a graphite boat structure and liquid phase epitaxial growth process for liquid phase epitaxial growth. Background Technology

[0002] Mercury cadmium telluride (MCH) is an important infrared photosensitive material. By changing the cadmium composition, its bandgap can be adjusted, allowing its detection range to cover all infrared wavelengths; it is one of the most commonly used materials for fabricating high-performance infrared focal plane array detectors. The fabrication of MCH thin films includes molecular beam epitaxy (MBE), metal-organic vapor phase epitaxy (MOVPE), and liquid phase epitaxy (LPE). Among these, liquid phase epitaxy technology for MCH materials has significant advantages in terms of photoresponse performance, fabrication cost, and dopant material growth, and is currently the most mature method for mass-producing MCH thin films. According to different growth methods, liquid phase epitaxy can be further subdivided into vertical immersion liquid phase epitaxy, tilting boat liquid phase epitaxy, and horizontal push-boat liquid phase epitaxy. Horizontal push-boat liquid phase epitaxy technology is widely used due to its advantages of simple growth equipment and low fabrication cost.

[0003] The thickness and compositional uniformity of mercury cadmium telluride (MCH) materials are key to determining the high resolution and high sensitivity performance of large-area array detectors. However, in the process of preparing MCH epitaxial films using tellurium-rich horizontal push-boat liquid phase epitaxy, a common process defect is the "edge effect," which manifests as a thicker epitaxial film at the edge and a thinner film at the center, severely affecting the thickness uniformity. Summary of the Invention

[0004] This invention provides a graphite boat structure and a liquid phase epitaxial growth process for liquid phase epitaxy, solving the problem of how to suppress edge effects in mercury cadmium telluride materials grown by tellurium-rich liquid phase epitaxy.

[0005] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, a graphite boat structure for liquid-phase epitaxial growth is provided, comprising: The graphite base is equipped with mounting positions for installing the mother liquor tank; A graphite mother liquor tank is used to contain the mother liquor for epitaxial growth, and the mother liquor tank is detachably connected to the mounting tank. A slider is slidably connected between the graphite mother liquor tank and the graphite base. The slider is used to support the substrate and can optionally slide directly below the graphite mother liquor tank for epitaxial growth. The heat-insulating medium module is configured to be optionally nested outside the mother liquor receiving part of the graphite mother liquor tank to form a structure in which the heat-insulating medium covers the growth region. The thermal conductivity of the heat-resistant medium module is lower than that of the graphite base and the graphite mother liquor tank.

[0006] Furthermore, the graphite boat structure also includes a graphite boat cover, which is placed on the graphite base and covers the graphite mother liquor tank, the sliding strip, and the heat-insulating medium module to reduce the evaporation of the mother liquor.

[0007] Furthermore, the heat-insulating medium module has a ring structure and is made of quartz or heat-insulating ceramic.

[0008] Furthermore, the thickness of the heat-insulating medium module is determined based on the length and width of the graphite base. When the graphite boat structure has a set ratio in length and width, the thickness of the heat-insulating medium nested on both sides of the length direction is less than the thickness of the heat-insulating medium nested on both sides of the width direction.

[0009] Furthermore, the mounting position is configured with two slots parallel to the sliding direction of the slider, and the graphite mother liquor tank includes a tank body and a protrusion corresponding to the slots; When the protruding part of the graphite mother liquor tank is inserted into the slot, the gap between the bottom of the graphite mother liquor tank and the graphite base forms the slide rail of the slider.

[0010] In a second aspect, a liquid phase epitaxial growth process is provided, which employs a graphite boat structure as described in the first aspect for horizontal push-boat type liquid phase epitaxial growth. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a graphite boat structure provided in an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a graphite base provided in an embodiment of this application; Figure 3 A schematic diagram of the assembly of a heat-insulating medium module and a graphite mother liquor tank provided for an embodiment of this application; Figure 4 This is a schematic diagram of a heat-resistant structural module provided in an embodiment of this application.

[0012] Reference numerals in the attached drawings: 1. Graphite base; 101. Slot; 2. Sliding bar; 3. Graphite mother liquor tank; 301. Tenon; 4. Heat-insulating medium; 5. Graphite boat cover. Detailed Implementation

[0013] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the technical solutions in the embodiments of this application are clearly described. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art are within the scope of protection of this application.

[0014] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0015] The steps described in the specification and the flowcharts in the accompanying drawings of this invention are not necessarily strictly executed according to the step numbers; the execution order of the method steps can be changed. Furthermore, certain steps can be omitted, multiple steps can be combined into one step, and / or one step can be broken down into multiple steps.

[0016] In typical horizontal pushboat liquid phase epitaxial growth, during the thin film growth stage, the substrate material is located directly below the mother liquor, which is surrounded by graphite. The graphite boat system cools down slowly. Due to the high thermal conductivity of graphite, the edge temperature of the mother liquor is lower than that of the center. This is an important reason for the edge effect of material thickness. This radial temperature gradient makes the supersaturation of the mother liquor higher in the edge region, which leads to an accelerated crystallization rate of mercury cadmium telluride at the edge, ultimately forming a non-uniform epitaxial layer that is thin in the center and thick at the edge.

[0017] Based on this, this specification provides a graphite boat structure for liquid phase epitaxial growth, and also relates to a liquid phase epitaxial growth process method, which aims to improve temperature field uniformity and enhance thermal stability to suppress edge effects. The following is a detailed description in conjunction with the accompanying drawings and preferred embodiments.

[0018] Please see Figure 1-4 This application provides a graphite boat structure for liquid-phase epitaxial growth, comprising: The graphite base 1 is provided with a mounting position for installing the mother liquor tank 3; Graphite mother liquor tank 3 is used to contain mother liquor for epitaxial growth, and the mother liquor tank 3 is detachably connected to the mounting tank; A slider 2 is slidably connected between the graphite mother liquor tank 3 and the graphite base 1. The slider 2 is used to support the substrate and can optionally slide directly below the graphite mother liquor tank 3 for epitaxial growth. The heat-insulating medium module 4 is configured to be optionally nested outside the mother liquor containing part of the graphite mother liquor tank 3 to form a structure in which the heat-insulating medium covers the growth region. The thermal conductivity of the heat-insulating medium module 4 is lower than that of the graphite base 1 and the graphite mother liquor tank 3.

[0019] In this application, the heat-insulating medium module 4 is configured as a replaceable independent component. Due to the characteristics of its heterogeneous material, it alters the heat conduction path and mode within the growth region. Specifically, this heterogeneous material can more effectively regulate heat distribution, resulting in more uniform heat conduction within the growth region. This avoids localized overheating or overcooling, thereby improving the thermal stability during epitaxial growth. This enhanced thermal stability contributes to the growth of materials with greater thickness and more uniform composition.

[0020] The heat-insulating medium module 4 is positioned on the outside of the graphite material, which avoids contamination from residual mother liquor caused by direct contact between the growth mother liquor and the liner, thus preventing difficulties in cleaning the liner and the risk of damage during cleaning. As the inner layer material that directly contacts the mother liquor, graphite allows for easy removal of residual mother liquor, ensuring that the graphite liner can be used stably and repeatedly for a long time, significantly reducing operating costs.

[0021] In some possible implementations, the graphite boat structure further includes a graphite boat cover 5, which covers the graphite mother liquor tank 3, the sliding strip 2, and the heat-insulating medium module 4 on the graphite base 1. The graphite boat cover 5 is positioned at the top of the graphite base 1 to reduce the evaporation of the mother liquor during the epitaxial process and to protect the internal structure.

[0022] Furthermore, the heat-insulating medium module 4 has a ring structure and is made of quartz or heat-insulating ceramic; it can also be a material with better heat-insulating properties than graphite, such as quartz or heat-insulating ceramic.

[0023] Furthermore, the thickness of the heat-insulating medium module 4 is determined based on the length and width of the graphite base 1. When the graphite boat structure has a set ratio in length and width, the thickness of the heat-insulating medium nested on both sides of the length direction is less than the thickness of the heat-insulating medium nested on both sides of the width direction.

[0024] See Figure 4 In other words, by making the thermal barrier medium a modular design, the thermal barrier medium material can be adjusted according to different epitaxial processes. The modular design of the thermal barrier medium makes process control more flexible and convenient. Specifically, the thickness design of the thermal barrier medium needs to be based on the structure of the graphite boat itself. Taking this graphite boat structure as an example, there is a large difference between the length and width of this graphite boat, and graphite itself has a certain thermal resistance. Therefore, the design thickness of the thermal barrier material in D1 needs to be less than that in D2. For the thicker graphite boat, the thickness of the thermal barrier medium in the length direction needs to be thinner than that in the width direction of the graphite boat.

[0025] Furthermore, the mounting position is configured with two slots 101 parallel to the sliding direction of the slider 2. The graphite mother liquor tank 3 includes a tank body and a protruding part corresponding to the slot 101. When the protruding part of the graphite mother liquor tank 3 is inserted into the slot 101, the gap between the bottom of the graphite mother liquor tank 3 and the graphite base 1 forms the slide rail of the slider 2. Specifically, the slot 101 is configured as a square slot, and the protruding part is configured as a tenon 301 corresponding to the square slot, which can be embedded in the slot 101 for fixation. The graphite base 1 and the graphite mother liquor tank 3 can form an enclosing structure, allowing the slider 2 to slide freely.

[0026] In summary, this application achieves a uniform temperature field structure in a graphite boat by adding heat-resistant materials around the growth solution and adjusting the thickness to alter the heat conduction mode. This improves the temperature field uniformity during epitaxial growth, thereby facilitating the production of epitaxial layers with high thickness uniformity and meeting the demands of semiconductor devices for high-performance epitaxial materials. Furthermore, the modular design of the heat-resistant structure allows for flexible material adjustments based on different epitaxial processes, enhancing the convenience of process control.

[0027] Compared to existing technologies, simply optimizing the geometry of the graphite boat or adjusting the temperature control program often yields limited results. Introducing other materials into the mother liquor contact area to alter heat conduction presents challenges such as preventing mother liquor contamination and ensuring easy cleaning and maintenance of components. This application effectively improves the temperature field uniformity of the horizontal push-boat LPE system. Simultaneously, the heat-insulating structure, coupled with specific slot connections, facilitates installation, resulting in a robust structure that can adapt to complex process conditions and ensure long-term stable operation. The slot design simplifies and simplifies the installation process, reducing operator workload and installation difficulty. Furthermore, this structure can adapt to complex conditions during epitaxial growth, ensuring long-term stable operation of the equipment and reducing maintenance costs.

[0028] Corresponding to the above-described graphite boat structure embodiment for liquid phase epitaxial growth, this application embodiment provides a liquid phase epitaxial growth process method, including: The graphite boat structure described above is used for horizontal pushboat-type liquid phase epitaxial growth.

[0029] The above-described liquid phase epitaxial growth process achieves the steps and processes of the above-described embodiment of the graphite boat structure for liquid phase epitaxial growth, and can achieve the same technical effect. To avoid repetition, it will not be described again here.

[0030] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0031] It is understood that the embodiments of this application have been described above in conjunction with the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. As those skilled in the art will know, various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. In addition, those skilled in the art, under the guidance or teaching of this application, can modify these features and embodiments to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of this invention.

Claims

1. A graphite boat structure for liquid-phase epitaxial growth, characterized in that, include: The graphite base is equipped with mounting positions for installing the mother liquor tank; A graphite mother liquor tank is used to contain the mother liquor for epitaxial growth, and the mother liquor tank is detachably connected to the mounting tank. A slider is slidably connected between the graphite mother liquor tank and the graphite base. The slider is used to support the substrate and can optionally slide directly below the graphite mother liquor tank for epitaxial growth. The heat-insulating medium module is configured to be optionally nested outside the mother liquor receiving part of the graphite mother liquor tank to form a structure in which the heat-insulating medium covers the growth region. The thermal conductivity of the heat-resistant medium module is lower than that of the graphite base and the graphite mother liquor tank.

2. The graphite boat structure for liquid-phase epitaxial growth according to claim 1, characterized in that, The graphite boat structure also includes a graphite boat cover, which is placed on the graphite base and covers the graphite mother liquor tank, the sliding strip, and the heat-insulating medium module to reduce the evaporation of the mother liquor.

3. The graphite boat structure for liquid-phase epitaxial growth according to claim 1, characterized in that, The heat-insulating medium module has a ring structure and is made of quartz or heat-insulating ceramic.

4. The graphite boat structure for liquid-phase epitaxial growth according to claim 1, characterized in that, The thickness of the heat-insulating medium module is determined based on the length and width of the graphite base. When the graphite boat structure has a set ratio in length and width, the thickness of the heat-insulating medium nested on both sides of the length direction is less than the thickness of the heat-insulating medium nested on both sides of the width direction.

5. The graphite boat structure for liquid-phase epitaxial growth according to claim 1, characterized in that, The mounting position is configured with two slots parallel to the sliding direction of the slider, and the graphite mother liquor tank includes a tank body and a protrusion corresponding to the slots; When the protruding part of the graphite mother liquor tank is inserted into the slot, the gap between the bottom of the graphite mother liquor tank and the graphite base forms the slide rail of the slider.

6. A liquid phase epitaxial growth process, characterized in that, Horizontal pushboat-type liquid phase epitaxial growth is performed using the graphite boat structure as described in claim 1.

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