Thermal diffusion sheet

Abstract

The utility model discloses a thermal diffusion sheet, which is applied to thermal diffusion of a wafer substrate in a molecular beam epitaxy process and comprises a thermal diffusion sheet body with a circular flat plate structure. A plurality of through hole structures are arranged on the heat diffusion sheet body in a central symmetry mode with the circle center of the heat diffusion sheet body as the center. And the opening size of each through hole structure is adjustable so as to adjust the duty ratio of the opening area of each through hole structure. The thermal diffusion sheet body is provided with the plurality of through hole structures, and the size of the duty ratio of the opening area of the through hole structures is adjustable, so that the heating temperature difference between different areas on the wafer substrate is reduced to a certain extent, the balance of the heating temperature of the substrate is ensured, and the molecular beam epitaxial growth effect of the substrate can also be improved.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor fabrication technology, and in particular to a heat diffusion sheet. Background Technology

[0002] Third-generation infrared focal plane detectors refer to infrared detectors characterized by large array size, very long wavelengths, dual-color or even multi-band operation, and low cost. The manufacturing process of their detector chips places higher demands on the area, performance, and reliability of mercury cadmium telluride (HCdT) materials. Molecular beam epitaxy (MBE) is the most promising mainstream technology for fabricating large-scale, dual-color, and other third-generation infrared focal plane detectors.

[0003] One of the most critical process requirements in molecular beam epitaxy (MBE) is substrate temperature uniformity, which affects the uniformity of the overall epitaxial quality (thickness, composition, defects, etc.). This is especially true for mercury cadmium telluride (HCd) MBE, where the growth window is very narrow. When the temperature exceeds the optimal value of ±5°C (the optimal solution is to keep the entire substrate temperature within ±3°C), the defect density increases significantly, potentially leading to polycrystalline structures. Therefore, ensuring uniform substrate heating temperature during the fabrication of the detector chip for third-generation infrared focal plane array detectors is one of the key technical challenges that need to be addressed in their fabrication. Utility Model Content

[0004] The purpose of this invention is to provide a thermal diffusion sheet that can improve the uniformity of substrate temperature during molecular beam epitaxy to a certain extent, thereby improving the uniformity of epitaxial film composition, thickness and crystal quality on the substrate, thus ensuring the reliability of the detection chip for the third-generation infrared focal plane detector.

[0005] To solve the above-mentioned technical problems, this utility model provides a heat diffusion sheet for use in the heat diffusion of wafer substrates during molecular beam epitaxy, comprising a heat diffusion sheet body having a circular flat plate structure;

[0006] The heat diffusion sheet body has a plurality of through-hole structures arranged symmetrically around the center of the heat diffusion sheet body; and the opening size of each through-hole structure is adjustable to adjust the duty cycle of the opening area of ​​the through-hole structure.

[0007] In one optional embodiment of this application, the heat diffusion sheet body includes a first annular region, a second annular region, and a third annular region that are sequentially divided and arranged along the radial direction of the heat diffusion sheet body;

[0008] The centers of the first annular region, the second annular region, and the third annular region coincide with the center of the heat diffusion sheet body.

[0009] The opening area of ​​the through-hole structure corresponding to the first annular region, the second annular region, and the third annular region is independently adjustable.

[0010] In one optional embodiment of this application, the heat diffusion sheet bodies are stacked on top of each other, comprising a first heat diffusion sheet and a second heat diffusion sheet;

[0011] The first heat diffuser sheet has multiple first through holes that are centrally symmetrical about the center of the first heat diffuser sheet.

[0012] The second heat diffuser sheet has a plurality of second through holes that are centrally symmetrical about the center of the second heat diffuser sheet;

[0013] The central axes of symmetry of the first heat diffuser and the second heat diffuser coincide, and the first heat diffuser and the second heat diffuser can rotate relative to each other about the central axis of symmetry, so as to adjust the size of the overlapping area between the first through hole and the second through hole, so as to adjust the duty cycle of the opening area of ​​the heat diffuser body formed by the first heat diffuser and the second heat diffuser.

[0014] In an optional embodiment of this application, the central regions of the first heat diffuser and the second heat diffuser are respectively provided with a first circular through hole and a second circular through hole of the same size and arranged along the central axis;

[0015] The first through hole and the second through hole are respectively provided in the annular edge region of the first heat diffuser sheet and the second heat diffuser sheet.

[0016] In an optional embodiment of this application, the edge of the first circular through hole is provided with a plurality of limiting protrusions; the edge of the second circular through hole is correspondingly provided with a plurality of limiting grooves.

[0017] When each of the limiting protrusions is inserted into the limiting groove at a different position, the relative position between the first heat diffusion sheet and the second heat diffusion sheet rotates and changes about the central axis of the first circular through hole.

[0018] In an optional embodiment of this application, the edges of the first circular through hole and the second circular through hole are jointly provided with through hole markings to mark the limiting groove into which the limiting protrusion is inserted, so as to determine the size of the overlapping area between the first through hole and the second through hole by means of the through hole markings.

[0019] In one optional embodiment of this application, the area of ​​each first through hole on the first heat diffusion sheet is smaller than the area of ​​each second through hole on the second heat diffusion sheet;

[0020] Furthermore, along the radial direction on the first heat diffuser sheet, the duty cycle of the opening area of ​​the first through hole first increases and then decreases.

[0021] In one optional embodiment of this application, the first through hole on the first heat diffuser sheet has the same structural surface shape as the non-opening region on the second heat diffuser sheet, so that the first through hole and the second through hole are complementary.

[0022] In one optional embodiment of this application, the second heat diffuser sheet includes a first annular sheet, a second annular sheet, and a third annular sheet arranged concentrically;

[0023] Wherein, the inner ring through hole of the first annular piece is the circular through hole;

[0024] The outer ring edge of the first annular piece and the inner ring edge of the second annular piece are movably connected, and the first annular piece and the second annular piece can be rotated relative to each other with the center of the second circular through hole as the center.

[0025] The outer ring edge and the inner ring edge of the second annular piece are movably connected; and the second annular piece and the third annular piece can be rotated relative to each other with the center of the second circular through hole as the center.

[0026] In an optional embodiment of this application, the heat diffusion sheet body includes a removable filler sheet filled in each of the through-hole structures, which is used to adjust the duty cycle of the opening area of ​​the unfilled through-hole structures on the heat diffusion sheet body by adjusting the number of filler sheets filled in each of the through-hole structures.

[0027] The present invention provides a heat diffusion sheet for use in the heat diffusion of wafer substrates during molecular beam epitaxy. The heat diffusion sheet includes a heat diffusion sheet body with a circular flat plate structure. A plurality of through-hole structures are centrally symmetrically arranged on the heat diffusion sheet body with respect to the center of the body. The size of the opening of each through-hole structure is adjustable to adjust the duty cycle of the opening area of ​​the through-hole structure.

[0028] The thermal diffusion sheet involved in this application is radiatively heated by a heater during molecular beam epitaxy (MBE) and then attached to the surface of a wafer substrate for thermal diffusion heating of the substrate. Furthermore, this application incorporates several through-hole structures on the thermal diffusion sheet body, with adjustable aperture sizes and duty cycles. This allows for the selection of appropriate duty cycles for the through-hole structures during the actual thermal diffusion process on the wafer substrate. This enables the rational control of the area ratio between radiative heating and thermal diffusion heating in the edge regions of the wafer substrate, thereby reducing the temperature difference between different areas of the wafer substrate and ensuring temperature uniformity, thus improving the effectiveness of MBE growth. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of 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.

[0030] Figure 1 This is a schematic diagram of the exploded structure of the substrate heating structure during molecular beam epitaxy.

[0031] Figure 2 This is a schematic diagram of the structure of a heat diffusion sheet provided in an embodiment of this application;

[0032] Figure 3 This is a schematic diagram of the structure of the first heat diffusion sheet provided in an embodiment of this application;

[0033] Figure 4 This is a schematic diagram of the structure of the second heat diffusion sheet provided in an embodiment of this application;

[0034] Figure 5 This is another structural schematic diagram of the heat diffusion sheet provided in the embodiments of this application;

[0035] Figure 6 A partial structural diagram showing the interconnection of the edges of the first circular through hole and the second circular through hole provided in an embodiment of this application;

[0036] Figure 7 Another schematic diagram of the structure of the heat diffusion sheet provided in the embodiments of this application;

[0037] In the attached figures: 10 is the substrate support, 11 is the wafer substrate, 12 is the heat diffuser sheet, 13 is the heater, 20 is the heat diffuser sheet body, 201 is the circular through-hole, 202 is the through-hole structure, 203 is the first annular region, 204 is the second annular region, 205 is the third annular region, 206 is the filler sheet, 21 is the first heat diffuser sheet, 210 is the first circular through-hole, 2101 is the serrated structure, 211 is the first through-hole, 22 is the second heat diffuser sheet, 220 is the second circular through-hole, 2201 is the pointed protrusion, 221 is the second through-hole, and 222 is the non-opening region. Detailed Implementation

[0038] like Figure 1 As shown, during molecular beam epitaxy, the wafer substrate 11 is placed on a circular substrate holder 10, with its first surface exposed downwards for epitaxial growth. The second surface of the wafer substrate 11 is directly bonded to a heat diffuser 12, and a heater 13 is positioned above the heat diffuser 12. The heater 13 heats the heat diffuser 12 through thermal radiation, while the heat diffuser 12 heats the wafer substrate 11 through thermal conduction. Furthermore, during epitaxial growth, the substrate holder 10 drives the wafer substrate 11 and the heat diffuser 12 to rotate synchronously, resulting in a centrally symmetrical temperature field around the wafer substrate 11 about its central axis of symmetry. Compared to the direct thermal radiation heating of the wafer substrate 11 by the heater 13, the thermal conduction heating method using the heat diffuser 12 not only increases the heating temperature of the wafer substrate 11 but also improves the temperature uniformity of the wafer substrate 11. Nevertheless, there is still a problem of temperature imbalance between different regions on the wafer substrate 11, which makes it impossible for the temperature difference between different regions on the wafer substrate 11 to meet the requirements for temperature uniformity of the wafer substrate 11 during molecular beam epitaxy.

[0039] Therefore, this application provides a technical solution that can greatly improve the uniformity of substrate heating temperature, ensuring the uniformity of the thickness of the structural layer formed by epitaxial growth on the substrate using molecular beam epitaxy technology.

[0040] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] like Figure 2 As shown, Figure 2This is a schematic diagram of the structure of a heat diffusion sheet provided in an embodiment of this application; Figure 3 This is a schematic diagram of the structure of the first heat diffusion sheet provided in an embodiment of this application; Figure 4 This is a schematic diagram of the structure of the second heat diffusion sheet provided in an embodiment of this application; Figure 5 This is another structural schematic diagram of the heat diffusion sheet provided in the embodiments of this application; Figure 6 This is another schematic diagram of the structure of the heat diffusion sheet provided in the embodiments of this application.

[0042] It is understood that the thermal diffusion sheet in this application is mainly used for the heating process of thermal diffusion of wafer substrate in molecular beam epitaxy.

[0043] In one specific embodiment of this application, the heat diffusion sheet may include:

[0044] A heat diffusion sheet body 20 with a circular flat plate structure;

[0045] The heat diffuser body 20 has a number of through-hole structures 202 arranged symmetrically around the center of the heat diffuser body 20; and the size of the opening of each through-hole structure 202 is adjustable to adjust the duty cycle of the opening area of ​​the through-hole structure 202.

[0046] As mentioned above Figure 1 As shown, because the heat diffuser needs to be in contact with the wafer substrate 11 during actual operation, the shape and structure of the heat diffuser body 20 can be set as a circular plate structure that is the same as or similar to the shape and structure of the wafer substrate 11. Furthermore, during molecular beam epitaxy, the wafer substrate 11 and the heat diffuser body 20 need to rotate synchronously with the substrate holder 10; therefore, the overall temperature field of the wafer substrate 11 is centrally symmetrically distributed. Accordingly, the via structures 202 opened on the heat diffuser body 20 should also be centrally symmetrically distributed.

[0047] Based on this, the location of the through-hole structure 202 on the heat diffusion sheet body 20 is heated by thermal radiation; thus, in the actual heating process of the wafer substrate 11, the through-hole structure 202 can be used to change the area with a high heating temperature due to heat diffusion to thermal radiation heating, thereby effectively adjusting the temperature uniformity of the entire wafer substrate 11.

[0048] Therefore, in this embodiment, by creating through-hole structures 202 on the edge region of the heat diffusion sheet, both thermal radiation heating and thermal diffusion heating are interleaved in the edge region of the entire wafer substrate 11. Furthermore, the smaller the duty cycle of the opening area on the heat diffusion sheet body 20, the better the heating effect on the wafer substrate 11, and the more heat can be conducted; conversely, the larger the duty cycle of the opening area on the heat diffusion sheet body 20, the worse the heating effect on the wafer substrate 11, and the less heat can be conducted. Considering that the temperature field distribution formed by the heater 13 and the heat diffusion sheet body 20 heating the wafer substrate 11 during epitaxial growth on different wafer substrates 11 is not constant, this approach ensures that the heating field distribution is not fixed. Therefore, in this embodiment, to ensure that the heat diffusion sheet can better adapt to the heating requirements of various wafer substrates 11, each via structure 202 can be further configured as a structure with adjustable aperture size. Thus, in practical applications, when different wafer substrates 11 need to be epitaxially grown, a suitable aperture size can be selected accordingly, so that the aperture area duty cycle of the via structure 202 in different locations within the edge region of the heat diffusion sheet body 20 changes accordingly, thereby adapting to the heating and temperature control requirements of different wafer substrates 11, and ultimately ensuring the temperature uniformity of the entire wafer substrate 11.

[0049] Furthermore, because the wafer substrate 11 and the heat diffuser body 20 remain in close contact and rotate synchronously around their coincident central axes, the temperature unevenness of the wafer substrate 11 during the heating process by the heat diffuser body 20 is mainly due to a temperature gradient in its radial direction. Therefore, in this application, a through-hole structure 202 is formed on the heat diffuser body 20, and the size of the through-hole structure 202 is adjustable, thereby allowing the duty cycle of the opening area of ​​the heat diffuser body 20 in the radial direction to be adjustable.

[0050] Based on this, considering that the temperature gradient of the wafer substrate 11 changes in the radial direction, in order to better ensure the temperature field uniformity on the wafer substrate 11, in an optional embodiment of this application, the heat diffusion sheet body 20 may further include:

[0051] The heat diffuser body 20 includes a first annular region 203, a second annular region 204 and a third annular region 205 arranged sequentially along the radial direction of the heat diffuser body 20.

[0052] Among them, the centers of the first annular region 203, the second annular region 204 and the third annular region 205 coincide with the center of the heat diffusion plate body 20;

[0053] The duty cycle of the opening area of ​​the through-hole structure 202 in the first annular region 203, the second annular region 204 and the third annular region 205 can be adjusted independently.

[0054] As mentioned above, the temperature field of the wafer substrate 11 is centrally symmetrically distributed. The temperature of the wafer substrate 11 should mainly have a temperature gradient in the radial direction, while there is basically no temperature gradient in the same circumferential direction. Therefore, in order to improve the temperature uniformity of the wafer substrate 11, it is mainly necessary to reduce the temperature difference of the wafer substrate 11 in the radial direction.

[0055] Based on this, this embodiment follows Figure 2 The heat diffuser body 20 is divided into at least three annular regions along the radial direction, as shown by the dashed lines: a first annular region 203, a second annular region 204, and a third annular region 205. The duty cycle of the via structures 202 within each of the three different annular regions is independently adjustable. Therefore, when the temperature of the portion of the wafer substrate 11 bonded to the second annular region 204 is higher than the temperature of the portions bonded to the first annular region 203 and the third annular region 205, the duty cycle of the via structures 202 within the second annular region 204 can be increased, while the duty cycle of the via structures 202 within the first annular region 203 and the third annular region 205 can be decreased. This results in a decrease in the temperature of the portion of the wafer substrate 11 bonded to the second annular region 204, while the temperature of the portions bonded to the first annular region 203 and the third annular region 205 increases, effectively reducing the temperature difference along the radial direction on the wafer substrate 11.

[0056] Therefore, in this application, by dividing the heat diffusion sheet body 20 into multiple annular regions along the radial direction, and making the duty cycle of the opening area of ​​the through-hole structure 202 in each annular region independently adjustable, it is equivalent to adjusting the temperature difference between different circumferential regions on the wafer substrate 11 by adjusting the duty cycle of the through-hole structure 202 corresponding to multiple different circumferential regions on the heat diffusion sheet. This can reduce the temperature gradient of the wafer substrate 11 in the radial direction, thereby greatly improving the temperature uniformity of the wafer substrate 11.

[0057] Based on the above discussion, in order to adjust the opening size of each through-hole structure 202 on the heat diffusion sheet body 20, such as Figures 3 to 5 As shown, in an optional embodiment of this application, the heat diffuser body 20 may further include:

[0058] A first heat diffuser sheet 21 and a second heat diffuser sheet 22 are stacked on top of each other;

[0059] Among them, a plurality of first through holes 211 are provided on the first heat diffusion plate 21 in a centrally symmetrical manner about the center of the first heat diffusion plate 21;

[0060] Multiple second through holes 221 are provided on the second heat diffuser plate 22 in a centrally symmetrical manner about the center of the second heat diffuser plate 22;

[0061] The central axes of symmetry of the first heat diffuser 21 and the second heat diffuser 22 coincide, and the first heat diffuser 21 and the second heat diffuser 22 can rotate relative to each other with the central axis of symmetry as the center of rotation, so as to adjust the size of the overlapping area between the first through hole 211 and the second through hole 221, so as to adjust and change the duty cycle of the opening area of ​​the heat diffuser body 20 formed by the first heat diffuser 21 and the second heat diffuser 22.

[0062] In this embodiment, the heat diffusion sheet body 20 includes a first heat diffusion sheet 21 and a second heat diffusion sheet 22 stacked on each other. A first through hole 211 and a second through hole 221 are respectively provided on the first heat diffusion sheet 21 and the second heat diffusion sheet 22. The first heat diffusion sheet 21 and the second heat diffusion sheet 22 can also rotate relative to each other. Thus, when the first heat diffusion sheet 21 and the second heat diffusion sheet 22 rotate relative to each other until the first through hole 211 and the second through hole 221 are directly opposite each other and overlap, the overlapping area of ​​the two forms a through hole structure 202 that can realize the thermal radiation heating of the wafer substrate 11. When the first heat diffusion sheet 21 and the second heat diffusion sheet 22 rotate relative to each other until the first through hole 211 and the second through hole 221 do not overlap at all, the first heat diffusion sheet 21 and the second heat diffusion sheet 22 together perform complete thermal diffusion heating on the wafer substrate 11. In practical applications, the rotational adjustment between the first heat diffuser plate 21 and the second heat diffuser plate 22 can gradually adjust between complete overlap and complete non-overlap between the first through hole 211 and the second through hole 221, thereby realizing the adjustment of the duty cycle of the opening area of ​​the through hole structure 202 corresponding to the heat diffuser plate body 20 formed by the first heat diffuser plate 21 and the second heat diffuser plate 22.

[0063] Furthermore, during molecular beam epitaxy, the thermal diffuser body 20 needs to rotate together with the wafer substrate 11. Therefore, although the first thermal diffuser 21 and the second thermal diffuser 22 can be adjusted relative to each other, during molecular beam epitaxy, it is necessary to ensure that the first thermal diffuser 21 and the second thermal diffuser 22 remain relatively fixed.

[0064] Based on the above discussion, in the actual heating process of the wafer substrate 11, the temperature difference in different areas of the wafer substrate 11 will also be caused by the different structures of the heater or the substrate support 10. For example, if the substrate support 10 is only supported by a few claws, the temperature in the central area of ​​the wafer substrate 11 will often be higher.

[0065] Therefore, in an optional embodiment of this application, a circular through hole 201 may be opened in the central region of the heat diffusion sheet body 20; and on the annular edge region of the heat diffusion sheet body 20, a plurality of through hole structures 202 are provided in a centrally symmetrical manner with respect to the center of the heat diffusion sheet body 20, and the duty cycle of the opening area of ​​each through hole structure 202 is symmetrically adjustable with respect to the center of the heat diffusion sheet body 20.

[0066] In this embodiment, to avoid excessively high temperatures in the central region of the wafer substrate 11, a circular through-hole 201 is provided in the central region of the heat diffusion sheet body 20. That is, the central region of the heat diffusion sheet body 20 does not conduct heat through diffusion to the central region of the wafer substrate 11; instead, the central region of the wafer substrate 11 is directly heated by heat radiation from the heater 13. Thus, while heating the central region of the wafer substrate 11, the problem of excessively high temperatures in the central region is avoided. Furthermore, the size of the circular through-hole 201 on the heat diffusion sheet body 20 can be determined based on a comprehensive consideration of factors such as the size of the wafer substrate 11 and the heating power of the heater 13; no specific limitations are imposed in this application.

[0067] Therefore, in this embodiment, during the thermal diffusion heating of the wafer substrate 11, the circular through-hole 201 located in the central region of the thermal diffusion sheet body 20 reduces the temperature imbalance between the central region and the edge region of the wafer substrate 11; at the same time, the duty cycle of the opening area of ​​the through-hole structure 202 in the upper edge region of the thermal diffusion sheet body 20 is adjustable, which reduces the temperature gradient change in the radial direction of the upper edge region of the wafer substrate 11, thereby maximizing the overall temperature uniformity of the wafer substrate 11.

[0068] Furthermore, in embodiments where the heat diffuser body 20 includes a first heat diffuser 21 and a second heat diffuser 22, it may include:

[0069] The central regions of the first heat diffuser 21 and the second heat diffuser 22 are respectively provided with a first circular through hole 210 and a second circular through hole 220 of the same size and arranged along the central axis; the edge region of the first heat diffuser 21 is provided with a plurality of first through holes 211 in a centrally symmetrical manner about the center of the first circular through hole 210; the edge region of the second heat diffuser 22 is provided with a plurality of second through holes 221 in a centrally symmetrical manner about the center of the second circular through hole 220.

[0070] Furthermore, the first heat diffuser plate 21 and the second heat diffuser plate 22 can be rotated relative to each other with the central axis of the first circular through hole 210 as the center, so as to adjust the size of the overlapping area between the first through hole 211 and the second through hole 221.

[0071] In this embodiment, the heat diffusion sheet body 20 includes a first heat diffusion sheet 21 and a second heat diffusion sheet 22 stacked on top of each other. A first circular through hole 210 and a second circular through hole 220 are respectively opened in the central region of the first heat diffusion sheet 21 and the second heat diffusion sheet 22. Thus, a circular through hole 201 formed by the interconnection of the first circular through hole 210 and the second circular through hole 220 can be formed in the central region of the overall structure of the stacked first heat diffusion sheet 21 and the second heat diffusion sheet 22, thereby realizing thermal radiation heating of the central region of the wafer substrate 11.

[0072] Based on this, a first through hole 211 and a second through hole 221 are respectively provided in the edge regions of the first heat diffusion sheet 21 and the second heat diffusion sheet 22, and the first heat diffusion sheet 21 and the second heat diffusion sheet 22 can also rotate relative to each other. Thus, when the first heat diffusion sheet 21 and the second heat diffusion sheet 22 rotate relative to each other until the first through hole 211 and the second through hole 221 are directly opposite each other and overlap, the overlapping area of ​​the two forms a through hole structure 202 that can realize the thermal radiation heating of the wafer substrate 11; and when the first heat diffusion sheet 21 and the second heat diffusion sheet 22 rotate relative to each other until the first through hole 211 and the second through hole 221 do not overlap at all, the first heat diffusion sheet 21 and the second heat diffusion sheet 22 together perform complete thermal diffusion heating on the edge region of the wafer substrate 11. In practical applications, the rotational adjustment between the first heat diffuser plate 21 and the second heat diffuser plate 22 can gradually adjust between complete overlap and complete non-overlap between the first through hole 211 and the second through hole 221, thereby realizing the adjustment of the duty cycle of the opening area of ​​the through hole structure 202 corresponding to the heat diffuser plate body 20 formed by the first heat diffuser plate 21 and the second heat diffuser plate 22.

[0073] As described above, during molecular beam epitaxy, the thermal diffuser body 20 needs to rotate together with the wafer substrate 11. Therefore, although the first thermal diffuser 21 and the second thermal diffuser 22 can be adjusted relative to each other, during molecular beam epitaxy, it is necessary to ensure that the first thermal diffuser 21 and the second thermal diffuser 22 remain relatively fixed.

[0074] Therefore, in an optional implementation of this embodiment, the heat diffusion sheet body 20 may further include:

[0075] The edge of the first circular through hole 210 is provided with multiple limiting protrusions; the edge of the second circular through hole 220 is correspondingly provided with multiple limiting grooves.

[0076] When each limiting protrusion is inserted into a limiting groove at a different position, the relative position between the first heat diffusion plate 21 and the second heat diffusion plate 22 rotates and changes around the central axis of the first circular through hole 210.

[0077] In this embodiment, multiple limiting protrusions and multiple limiting grooves are respectively provided on the edges of the first circular through hole 210 on the first heat diffuser 21 and the second circular through hole 220 on the second heat diffuser 22. These limiting protrusions and limiting grooves can be connected to each other. Therefore, in practical applications, when the first heat diffuser 21 and the second heat diffuser 22 are fitted together, each limiting protrusion is inserted into its corresponding limiting groove, thus achieving a fixed connection between the first heat diffuser 21 and the second heat diffuser 22. Furthermore, when it is necessary to adjust the first through hole 211 and the second through hole 220... When adjusting the size of the overlapping area between the two heat diffusers 21 and 22, the first heat diffuser 21 and the second heat diffuser 22 can be separated from each other. After rotating the first heat diffuser 21 and the second heat diffuser 22 relative to each other, the first heat diffuser 21 and the second heat diffuser 22 can be reconnected. During this process, the limiting grooves into which the limiting protrusions are inserted change, thereby restoring the relative fixed connection between the first through hole 211 and the second through hole 221 when the size of the overlapping area between the first through hole 211 and the second through hole 221 changes. Because of the limiting effect of the connection between the limiting protrusions and the limiting grooves, the first heat diffuser 21 and the second heat diffuser 22 can also remain relatively fixed when they rotate with the wafer substrate 11.

[0078] Optionally, the heat diffusion sheet body 20 in this embodiment may further include:

[0079] The edges of the first circular through hole 210 and the second circular through hole 220 are jointly provided with through hole markings to mark the limiting groove into which the limiting protrusion is inserted, so as to determine the size of the overlapping area between the first through hole 211 and the second through hole 221 by means of the through hole markings.

[0080] In practical applications, a limiting groove can be selected to set a through-hole mark. When the overlapping area between the first through-hole 211 and the second through-hole 221 is at its maximum, the limiting protrusion inserted into the limiting groove with the through-hole mark is taken as the starting protrusion. The corresponding protrusion mark is set on each limiting protrusion in sequence according to the arrangement of each limiting protrusion. For example, the starting protrusion mark is 1, and the limiting protrusion adjacent to the starting protrusion is marked as 0.8. This indicates that when the limiting protrusion is inserted into the limiting groove with the through-hole mark, the opening area duty cycle of the through-hole structure 202 formed by the overlapping area between the first through-hole 211 and the second through-hole 221 is only 80% of the maximum opening area duty cycle. By analogy, each limiting protrusion can be marked in sequence according to a similar rule. Thus, in practical applications, the way the first heat diffusion sheet 21 and the second heat diffusion sheet 22 cooperate and connect with each other can be selected according to actual needs, thereby controlling the opening area duty cycle of the through-hole structure 202 of the overall structure formed by the two together within a reasonable range.

[0081] like Figure 6 As shown, Figure 6 The diagram shown is a partial structural schematic of the connection between the edge of the first circular through-hole 210 in the first heat diffuser 21 and the edge of the second circular through-hole 220 in the second heat diffuser 22. Figure 6 In the embodiment shown, the edge of the first circular through hole 210 is inserted and fitted inside the ring of the second circular through hole 220.

[0082] Considering that the first through-hole 211 and the second through-hole 221 respectively opened in the first heat diffusion plate 21 and the second heat diffusion plate 22 are distributed in a certain periodicity along the circumferential direction, therefore in Figure 6 In the embodiment shown, a serrated structure 2101 is provided only in a portion of the arc-shaped section on the inner ring wall of the first circular through hole 210. Correspondingly, only one pointed protrusion 2201 is provided on the second circular through hole 220. As the pointed protrusion 2201 on the second circular through hole 220 is inserted into the tooth gaps of the serrated structure 2101 at different positions on the first circular through hole 210, the first heat diffusion plate 21 and the second heat diffusion plate 22 can be connected to each other, thereby adjusting the overall opening area duty cycle of the two.

[0083] It should be noted that in practical applications, the sawtooth density of the sawtooth structure 2101 can be as large as possible, thereby enabling the overall opening area duty cycle of the first heat diffuser 21 and the second heat diffuser 22 to be adjusted in a fine and continuous manner, so as to adjust the most suitable opening area duty cycle for different wafers.

[0084] Based on the above discussion, the maximum opening area of ​​the through-hole structure 202 formed by the overlapping of the first through-hole 211 and the second through-hole 221 in the heat diffusion sheet body 20 of this application is determined by the through-hole with the smallest opening area among the first through-hole 211 and the second through-hole 221. In an optional embodiment of this invention, the area of ​​each first through-hole 211 on the first heat diffusion sheet 21 is smaller than the area of ​​each second through-hole 221 on the second heat diffusion sheet 22;

[0085] Furthermore, along the radial direction on the first heat diffuser plate 21, the duty cycle of the opening area of ​​the first through hole 211 first increases and then decreases.

[0086] In this embodiment, each first through-hole 211 on the first heat diffusion sheet 21 is smaller than the second through-hole 221 on the second heat diffusion sheet 22. Therefore, the maximum opening area duty cycle of the through-hole structure 202 on the heat diffusion sheet body 20 is also the opening area duty cycle of the first through-hole 211 on the first heat diffusion sheet 21. Of course, it is understood that, generally, the opening area duty cycle of the first through-hole 211 on the first heat diffusion sheet 21 should be less than 50%. Furthermore, in practical applications, the first heat diffusion sheet 21 should preferably be directly attached to the wafer substrate 11, while the second heat diffusion sheet 22 is located on the side of the first heat diffusion sheet 21 facing away from the wafer substrate 11.

[0087] Based on this, one of the simplest ways to implement the first heat diffuser 21 and the second heat diffuser 22 is that the first through hole 211 on the first heat diffuser 21 and the non-opening area 222 on the second heat diffuser 22 have the same structural surface shape, so that the first through hole 211 and the second through hole 221 are complementary.

[0088] like Figure 3 and Figure 4As shown, in this embodiment, the first through hole 211 can be a through hole extending radially along the first heat diffuser plate 21, and the two side walls of the first through hole 211 are curved side walls, making the first through hole 211 generally a through hole with a wide middle section and narrow ends. The shape and structure of the non-opening region 222 on the second heat diffuser plate 22 are exactly the same as the shape and structure of the first through hole 211, and the shape of the second through hole 221 on the second heat diffuser plate 22 is complementary to the shape of the first through hole 211. Therefore, when the first through hole 211 on the first heat diffuser plate 21 is completely aligned with the region where the second through hole 221 is located, the opening area of ​​the through hole structure 202 of the heat diffuser plate body 20 is the largest, which is equal to the opening area of ​​the first through hole 211 on the first heat diffuser plate 21. As the first heat diffuser 21 and the second heat diffuser 22 rotate relative to each other, the non-perforated area 222 on the second heat diffuser 22 gradually covers the first through hole 211. The larger the covered area, the smaller the duty cycle of the through hole structure 202 of the heat diffuser body 20. When the non-perforated area 222 on the second heat diffuser 22 exactly covers the first through hole 211, the duty cycle of the through hole structure 202 of the heat diffuser body 20 is 0. In this embodiment, the first through hole 211 and the second through hole 221 are set as complementary structures, so that the overall structure of the first heat diffuser 21 and the second heat diffuser 22 is approximately equal to the structure of a complete heat diffuser without through holes. This helps to reduce the overall material consumption of the first heat diffuser 21 and the second heat diffuser 22, thereby reducing the cost of the heat diffuser.

[0089] It is understandable that, given that the central region of the wafer substrate 11 is heated by thermal radiation, the temperature should be highest in the central region of the edge region of the wafer substrate 11. Therefore, in this embodiment, based on the fact that the opening area of ​​the through-hole structure 202 of the heat diffusion sheet body 20 is determined by the first through-hole 211 on the first heat diffusion sheet 21, the duty cycle of the opening area of ​​the first through-hole 211 on the first heat diffusion sheet 21 is set to first increase and then decrease in the radial direction. This results in the largest duty cycle of the opening area corresponding to the central region of the edge region of the first heat diffusion sheet 21, which is beneficial for maintaining the temperature uniformity of the edge region of the wafer substrate 11.

[0090] In practical applications, the first through hole 211 on the first heat diffuser 21 can be as follows: Figure 2 The first through-hole 211 extends radially, and its width first increases and then decreases. In another optional implementation of this embodiment, the first through-hole 211 can also be a plurality of small through-holes arranged sequentially along the same radial direction of the first heat diffuser 21, and the area of ​​each first through-hole 211 first increases and then decreases radially. Of course, in practical applications, the first through-hole 211 is not limited to... Figure 2 and Figure 3 The structural forms shown do not necessarily require that the first through holes 211 in different circumferential directions be distributed in the same few radial directions in a one-to-one correspondence; and the shape of each first through hole 211 is not limited to a circle or an ellipse, but can also be a fan-shaped through hole, etc. No specific restrictions are made in this application.

[0091] Based on the above embodiments, in an optional embodiment of this application, the edge region of the heat diffusion sheet body 20 can be divided into at least three annular regions along the radial direction, and the duty cycle of the opening area of ​​the through-hole structure 202 corresponding to the three annular regions is adjustable. On this basis, the opening area of ​​the through-hole structure 202 in the three different annular regions of the heat diffusion sheet body 20 is adjustable through the first heat diffusion sheet 21 and the second heat diffusion sheet 22.

[0092] The heat diffusion sheet body 20 may specifically include:

[0093] The second heat diffuser 22 includes a first annular plate, a second annular plate, and a third annular plate arranged concentrically;

[0094] Among them, the inner ring through hole of the first annular piece is a circular through hole 201;

[0095] The outer ring edge of the first annular piece and the inner ring edge of the second annular piece are movably connected, and the first annular piece and the second annular piece can be rotated relative to each other with the center of the second circular through hole 220 as the center.

[0096] The outer ring edge of the second annular piece and the inner ring edge of the second annular piece are movably connected; and the second annular piece and the third annular piece can be adjusted relative to each other with the center of the second circular through hole 220 as the center.

[0097] In this embodiment, the second heat diffuser 22 can be configured as follows: Figure 1 The dashed lines shown divide the heat diffusion sheet body 20 into three annular sheets in a manner similar to dividing annular regions. The three annular sheets are detachably spliced ​​together. After the first and second annular sheets, as well as the second and third annular sheets, are disassembled from each other, they can be rotated relative to each other by a certain angle before being spliced ​​together.

[0098] It is understandable that the shape of the first annular piece corresponds to the shape of the first annular region 203, the shape of the second annular piece corresponds to the shape of the second annular region 204, and the shape of the third annular piece corresponds to the shape of the third annular region 205.

[0099] Therefore, in practical applications, if the first annular piece and the second annular piece are disassembled from each other, and the first annular piece is rotated at a certain angle and then reassembled with the second annular piece, then only the duty cycle of the opening area of ​​the through hole structure 202 in the first annular region 203 of the heat diffusion sheet body 20 can be changed; similarly, the duty cycle of the opening area of ​​the through hole structure 202 in the second annular region 204 and the third annular region 205 can be adjusted independently.

[0100] In the above embodiments, the description mainly focuses on the example of a heat diffusion sheet body 20 comprising a first heat diffusion sheet 21 and a second heat diffusion sheet 22 stacked on top of each other. In practical applications, the heat diffusion sheet body 20 in this application does not necessarily need to include two layers of heat diffusion sheet structure.

[0101] like Figure 7 As shown, in another optional embodiment of this application, the heat diffusion sheet body 20 may further include:

[0102] The removable filler sheet 206 filled in each through hole structure 202 is used to adjust the duty cycle of the opening area of ​​the unfilled through hole structure 202 on the heat diffusion sheet body 20 by adjusting the number of filler sheets 206 filled in each through hole structure 202.

[0103] In this embodiment, each through-hole structure 202 can be equipped with a filler sheet 206 with the same shape and area as the through-hole structure 202. When it is necessary to change the duty cycle of the opening area of ​​the through-hole structure 202 on the heat diffusion sheet body 20, the corresponding filler sheet 206 can be filled into a portion of the through-hole structure 202, thereby changing the duty cycle of the opening area of ​​the through-hole structure 202 on the heat diffusion sheet body 20.

[0104] Alternatively, the filling sheet 206 corresponding to each through-hole structure 202 can be divided into several filling blocks that can be spliced ​​together. Thus, the duty cycle of the opening area of ​​the through-hole structure 202 can be changed by controlling the number of filling blocks filling each through-hole structure 202.

[0105] Obviously, in this embodiment, by filling each through-hole structure 202 with a filler sheet 206, the duty cycle of the opening area of ​​the through-hole structure 202 can be changed, and the independent adjustment of the duty cycle of the opening area of ​​each different region on the heat diffusion sheet can also be achieved.

[0106] In the above embodiments, the examples illustrate a support structure that does not provide thermal insulation for the edge region of the wafer substrate 11. In practical applications, if the substrate support 10 is surrounded by a metal cylinder, thus providing some thermal insulation for the edge of the wafer substrate 11, the temperature of the central region of the wafer substrate 11 is often higher than that of the edge region. In this case, a circular through-hole 201 does not need to be opened in the central region of the heat diffusion sheet body 20. In the embodiment where the heat diffusion sheet body 20 also includes a first heat diffusion sheet 21 and a second heat diffusion sheet 22 stacked together, the central regions of the first heat diffusion sheet 21 and the second heat diffusion sheet 22 may not have through-hole structures 202, or the central regions may also have first through-holes 211 and second through-holes 221 respectively. The overlap of the first through-holes 211 and the second through-holes 221 in the central region is independently adjustable relative to the overlap of the first through-holes 211 and the second through-holes 221 in the edge region, thereby making the temperature of the entire wafer substrate 11 as uniform as possible. The layout of the first through-holes 211 and the second through-holes 221 in the central regions of the first heat diffusion sheet 21 and the second heat diffusion sheet 22 can be the same as or similar to the layout of the first through-holes 211 and the second through-holes 221 in the edge regions of the first heat diffusion sheet 21 and the second heat diffusion sheet 22, which will not be repeated in this application.

[0107] In summary, the thermal diffusion sheet involved in this application is radiated and heated by a heater during molecular beam epitaxy (MBE), and then attached to the surface of the wafer substrate for thermal diffusion heating of the wafer substrate. Furthermore, this application incorporates a circular via in the central region of the thermal diffusion sheet, allowing the central region of the wafer substrate to be directly radiated and heated by the heater, preventing excessive temperature rise in the central region due to thermal diffusion heating from the thermal diffusion sheet itself. Additionally, this application provides several via structures on the edge region of the thermal diffusion sheet, and the size of each via structure is adjustable, allowing for adjustable duty cycles. This enables the selection of via structures with appropriate duty cycles based on the actual wafer substrate during thermal diffusion, thereby controlling the area ratio of radiative heating to thermal diffusion heating in the edge region of the wafer substrate. This reduces the temperature difference between different regions of the wafer substrate, ensuring temperature uniformity and improving the effectiveness of MBE growth.

[0108] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. 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 said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0109] This article uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made to this utility model without departing from the principles of this utility model, and these improvements and modifications also fall within the protection scope of this utility model.

Claims

1. A heat diffusion sheet, characterized in that, Thermal diffusion of wafer substrates used in molecular beam epitaxy processes includes a thermal diffusion sheet body with a circular flat plate structure; The heat diffusion sheet body has a plurality of through-hole structures arranged symmetrically around the center of the heat diffusion sheet body; and the opening size of each through-hole structure is adjustable to adjust the duty cycle of the opening area of ​​the through-hole structure.

2. The heat diffusion sheet as described in claim 1, characterized in that, The heat diffusion sheet body includes a first annular region, a second annular region, and a third annular region that are sequentially divided and arranged along the radial direction of the heat diffusion sheet body. The centers of the first annular region, the second annular region, and the third annular region coincide with the center of the heat diffusion sheet body. The opening area of ​​the through-hole structure corresponding to the first annular region, the second annular region, and the third annular region is independently adjustable.

3. The heat diffusion sheet as described in claim 1 or 2, characterized in that, The heat diffusion sheet body consists of a first heat diffusion sheet and a second heat diffusion sheet stacked on top of each other. The first heat diffuser sheet has multiple first through holes that are centrally symmetrical about the center of the first heat diffuser sheet. The second heat diffuser sheet has a plurality of second through holes that are centrally symmetrical about the center of the second heat diffuser sheet; The central axes of symmetry of the first heat diffuser and the second heat diffuser coincide, and the first heat diffuser and the second heat diffuser can rotate relative to each other about the central axis of symmetry, so as to adjust the size of the overlapping area between the first through hole and the second through hole, so as to adjust the duty cycle of the opening area of ​​the heat diffuser body formed by the first heat diffuser and the second heat diffuser.

4. The heat diffusion sheet as described in claim 3, characterized in that, The central regions of the first heat diffuser and the second heat diffuser are respectively provided with a first circular through hole and a second circular through hole of the same size and arranged along the central axis; The first through hole and the second through hole are respectively provided in the annular edge region of the first heat diffuser sheet and the second heat diffuser sheet.

5. The heat diffusion sheet as described in claim 4, characterized in that, The first circular through hole has multiple limiting protrusions surrounding its edge; the second circular through hole has correspondingly multiple limiting grooves surrounding its edge. When each of the limiting protrusions is inserted into the limiting groove at a different position, the relative position between the first heat diffusion sheet and the second heat diffusion sheet rotates and changes about the central axis of the first circular through hole.

6. The heat diffusion sheet as described in claim 5, characterized in that, The edges of the first circular through hole and the second circular through hole are jointly provided with through hole markings to mark the limiting groove into which the limiting protrusion is inserted, so as to determine the size of the overlapping area between the first through hole and the second through hole by means of the through hole markings.

7. The heat diffusion sheet as described in claim 5, characterized in that, The area of ​​each first through hole on the first heat diffuser is smaller than the area of ​​each second through hole on the second heat diffuser; Furthermore, along the radial direction on the first heat diffuser sheet, the duty cycle of the opening area of ​​the first through hole first increases and then decreases.

8. The heat diffusion sheet as described in claim 6, characterized in that, The first through hole on the first heat diffuser sheet has the same structural surface shape as the non-opening area on the second heat diffuser sheet, so that the first through hole and the second through hole are complementary.

9. The heat diffusion sheet as described in claim 4, characterized in that, The second heat diffuser sheet includes a first annular sheet, a second annular sheet, and a third annular sheet arranged concentrically; Wherein, the inner ring through hole of the first annular piece is the second circular through hole; The outer ring edge of the first annular piece and the inner ring edge of the second annular piece are movably connected, and the first annular piece and the second annular piece can be rotated relative to each other with the center of the second circular through hole as the center. The outer ring edge and the inner ring edge of the second annular piece are movably connected; and the second annular piece and the third annular piece can be adjusted relative to each other with the center of the second circular through hole as the center.

10. The heat diffusion sheet as described in claim 1, characterized in that, The heat diffusion sheet body includes removable filler sheets filled in each of the through-hole structures, which are used to adjust the duty cycle of the opening area of ​​the unfilled through-hole structures on the heat diffusion sheet body by adjusting the number of filler sheets filled in each of the through-hole structures.

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