A substrate holder in a molecular beam epitaxy production apparatus
By combining a graphite transition plate and a bottom plate, the problems of damage to molybdenum plates and temperature inhomogeneity in MBE production were solved, enabling the reuse of molybdenum plates and improving wafer quality.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GRAIN TECH (XIAMEN) CO LTD
- Filing Date
- 2025-05-08
- Publication Date
- 2026-06-09
Smart Images
Figure CN224337797U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor equipment, and in particular to a substrate support plate in a molecular beam epitaxy production equipment. Background Technology
[0002] Molecular beam epitaxy (MBE) is an advanced technology for epitaxial thin film deposition at the atomic level, playing a crucial role in semiconductor material preparation. In the mass-production-ready MBE epitaxial manufacturing process, improving the quality and efficiency of wafer epitaxial growth and reducing overall operating costs are of paramount importance for the continued development of MBE technology.
[0003] MBE-grade ultra-high purity molybdenum substrates are a key material in this technology, but their high price and manufacturing costs, coupled with a relatively long procurement and processing cycle, make them extremely expensive. In actual epitaxial growth, the surface of the molybdenum substrate often retains a thick layer of various thin film materials. To ensure the quality of epitaxial growth, the molybdenum substrate must be chemically cleaned regularly. If not cleaned in time, these residues will become impurities in the wafer epitaxial layer during high-temperature epitaxial growth, leading to quality problems.
[0004] However, chemical cleaning processes require the use of strong acids and alkalis. While these agents effectively remove residues from the surface of the molybdenum trays, they can also cause some damage to the trays themselves. This is especially true at the holes where the wafers are placed, which are extremely thin (typically only 0.5-1 mm). The corrosive effect of the chemicals can erode the molybdenum material, causing the holes to enlarge. After multiple cleaning cycles, the tray holes may no longer fit the wafers, ultimately rendering the trays unusable, wasting production resources, and resulting in higher production costs.
[0005] Meanwhile, during the MBE high-temperature epitaxial growth process, the substrate wafer is placed on a tray step, and the edge of the substrate is in close contact with the tray step. Due to the significant difference in physical properties between molybdenum and the epitaxial wafer material, the temperature difference between the wafer and the contact surface of the molybdenum tray occurs during the heating and cooling of the substrate heater. This results in a difference in heat distribution between the center and the edge of the wafer, forming thermal stress lines on the surface of the epitaxial wafer, which affects the wafer quality.
[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content
[0007] (a) Technical problems to be solved
[0008] This application provides a substrate tray in a molecular beam epitaxy production equipment, which can solve the problem of how to reduce production costs and improve wafer quality in the prior art.
[0009] (II) Technical Solution
[0010] To solve the above-mentioned technical problems, this application provides the following technical solution:
[0011] A substrate tray for a molecular beam epitaxy (MBE) production apparatus is provided, the substrate tray comprising: a base tray and a graphite transition tray;
[0012] The base plate is provided with a first through hole, and at least one first step is provided on the inner side of the first through hole;
[0013] The graphite transition plate is made of graphite crystal material, and its outer side is provided with a second step that matches the first step. The graphite transition plate is embedded in the first through hole, and the second step is supported on the first step. The middle part of the graphite transition plate is provided with a second through hole. The inner side of the second through hole is provided with a wafer step for placing the substrate wafer, a ring step for placing the heat-blocking ring, and a limiting step for restricting the movement of the heat-blocking ring in sequence along an axial direction.
[0014] In some embodiments, the inner sides of the wafer step, the annular step, and the limiting step are formed with circular holes whose radii increase sequentially and are coaxially aligned.
[0015] In some embodiments, the base plate is made of molybdenum.
[0016] In some embodiments, the base plate is provided with four first through holes evenly distributed, and the graphite transition plate is provided with four second through holes evenly distributed.
[0017] In some embodiments, the bottom support plate is provided with a slot inside the first through hole, and the graphite transition support plate is provided with a block on the outside. The block is engaged inside the slot to fix the bottom support plate and the graphite transition support plate in the circumferential direction of the first through hole.
[0018] In some embodiments, the number of the card blocks is at least two, and they are evenly distributed along the circumference of the first through hole.
[0019] (III) Beneficial Effects
[0020] Compared with the prior art, the beneficial effects of the technical solution provided in this application include at least the following:
[0021] The bottom support plate in the molecular beam epitaxy production equipment of this application can utilize the original scrapped support plate as a carrier for the graphite transition support plate, realizing the reuse of waste molybdenum support plates and reducing production costs.
[0022] Meanwhile, a graphite transition plate is added to the base plate as a carrier for the substrate wafer. Since the graphite transition plate uses graphite crystal material with similar physical properties to the substrate wafer, the wafer is heated more evenly, which effectively solves the problem of uneven temperature distribution of traditional substrates and significantly improves the product quality of epitaxial wafers. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a schematic diagram of the substrate support plate in the molecular beam epitaxy production equipment in the embodiments of this application;
[0025] Figure 2 This is a schematic diagram of the substrate tray explosion in the molecular beam epitaxy production equipment in this application embodiment;
[0026] Figure 3 This is a cross-sectional view of the substrate support plate in the molecular beam epitaxy production equipment in the embodiments of this application.
[0027] Figure label:
[0028] Base plate 1, first through hole 11, first step 12, slot 13;
[0029] Graphite transition plate 2, second step 21, second through hole 22, wafer step 221, annular step 222, limiting step 223, and locking block 23;
[0030] Chip 3.
[0031] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation
[0032] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.
[0033] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.
[0034] In existing molecular beam epitaxy (MBE) equipment, during the high-temperature epitaxial growth of substrate materials, the substrate wafer is placed on a tray step, with the substrate edge in close contact with the tray step. Due to the significant difference in physical properties between molybdenum and the epitaxial wafer material, a temperature difference occurs between the wafer and the contact surface with the molybdenum tray during the heating and cooling of the substrate heater. This difference in heat distribution between the center and edge of the wafer creates thermal stress lines on the epitaxial wafer surface, affecting wafer quality.
[0035] To address the aforementioned technical problems, this embodiment provides a substrate support plate in a molecular beam epitaxy (MBE) production apparatus. (See also...) Figures 1 to 3 As shown, Figure 1 This is a schematic diagram of the substrate support plate in the molecular beam epitaxy production equipment in the embodiments of this application. Figure 2 This is a schematic diagram of the substrate tray explosion in the molecular beam epitaxy production equipment in this application embodiment. Figure 3 This is a cross-sectional view of the substrate support plate in the molecular beam epitaxy production equipment in the embodiments of this application.
[0036] A substrate support plate in a molecular beam epitaxy production equipment includes: a base support plate 1 and a graphite transition support plate 2.
[0037] The base plate 1 has a first through hole 11, and at least one first step 12 is provided inside the first through hole 11. The base plate 1 can be a discarded 6-inch molybdenum tray, which itself has a first through hole 11 and a step for placing the wafer. In the actual epitaxial production process, a thick layer of various thin film materials will remain on the surface of the substrate molybdenum tray, which must be chemically cleaned regularly. Otherwise, these residues will enter the wafer epitaxial layer as impurities during high-temperature epitaxial growth, causing quality problems. Strong acids and alkalis are used in the chemical cleaning process, which, while removing residues from the surface of the molybdenum tray, also damage the molybdenum tray 1 itself. Since the thickness of the first through hole 11 where the wafer is placed is very thin, usually only 0.5-1mm, the chemical solution will corrode the molybdenum material, causing the first through hole 11 to expand. After multiple cleanings, the first through hole 11 will no longer be able to hold a wafer, leading to the scrapping of the tray and significant losses. To form the first step 12 on the molybdenum tray, the original step structure can be milled to remove excess step structure, such as... Figure 2 As shown by the dashed line.
[0038] The graphite transition tray 2 is made of graphite crystal material. Its outer side has a second step 21 adapted to the first step 12. The graphite transition tray 2 is embedded in the first through hole 11, and the second step 21 is supported on the first step 12. The graphite transition tray 2 has a second through hole 22 in its middle. Inside the second through hole 22, along an axial direction, are sequentially provided a wafer step 221 for placing a substrate wafer, a ring step 222 for placing a heat-blocking ring, and a limiting step 223 for restricting the movement of the heat-blocking ring. For example, the graphite transition tray 2 is used to place a 2-inch wafer 3, or to place wafers 3 of different sizes.
[0039] In some implementations, see Figure 2 As shown, the inner sides of the wafer step 221, the annular step 222, and the limiting step 223 are formed with successively increasing radii and coaxially aligned circular holes. The circular hole inside the wafer step 221 has the smallest radius and is used to directly support the substrate; the circular hole inside the annular step 222 has a larger radius than the circular hole inside the wafer step 221, forming a space that can accommodate the ring that blocks heat radiation; the circular hole inside the limiting step 223 has the largest radius, and its function is to further limit the substrate and prevent it from moving during epitaxial growth. When processing the graphite transition tray 2, high-precision processing techniques, such as CNC milling and EDM, are used to precisely machine the wafer step 221, the annular step 222, and the limiting step 223 onto the tray, ensuring that the radius and coaxiality of the circular holes inside each step meet the design requirements.
[0040] In some implementations, see Figure 1 As shown, the base plate 1 is evenly provided with 4 first through holes 11, and the graphite transition plate 2 is evenly provided with 4 second through holes 22.
[0041] To enhance the stability of the graphite transition plate 2 within the first through hole 11, in some embodiments, see [reference needed]. Figure 1 As shown, the bottom support plate 1 is provided with a slot 13 inside the first through hole 11, and the graphite transition support plate 2 is provided with a block 23 on the outside. The block 23 is placed inside the slot 13 to fix the bottom support plate 1 and the graphite transition support plate 2 in the circumferential direction of the first through hole 11.
[0042] During the machining of the base plate 1, a groove 13 is machined inside the first through hole 11 using milling or other processes. The size and shape of the groove 13 should match the locking block 23 to ensure that the locking block 23 can smoothly engage in the groove 13 and achieve a good fit. During the machining of the graphite transition plate 2, a locking block 23 is formed on the outside of the graphite transition plate 2 by machining. When assembling the base plate 1 and the graphite transition plate 2, align the locking block 23 of the graphite transition plate 2 with the groove 13 of the base plate 1, and gently push the graphite transition plate 2 to make the locking block 23 engage in the groove 13. To ensure the fit accuracy between the locking block 23 and the groove 13, a feeler gauge or other tools can be used to check whether the gap between the locking block 23 and the groove 13 meets the requirements.
[0043] Further, see Figure 1 As shown, there are at least two locking blocks 23, which are evenly distributed around the first through hole 11. For example, when four locking blocks 23 are provided, the included angle between each locking block 23 is 90°, and they are evenly distributed around the first through hole 11.
[0044] In summary, this embodiment utilizes a discarded 6-inch molybdenum tray, which is then reprocessed to introduce a graphite transition tray with four 2-inch graphite crystals, enabling the crystal growth of a 2-inch epitaxial wafer. During the MBE high-temperature epitaxial growth process, the substrate wafer is placed on the wafer steps of the graphite transition tray. Because graphite crystals are used as the substrate wafer carrier, and graphite has similar physical properties to the substrate wafer, the drawback of thermal stress lines formed on the epitaxial wafer surface due to differences in substrate temperature distribution is effectively solved, significantly improving the quality of the epitaxial wafer product. Simultaneously, the discarded molybdenum tray is reused, saving substantial funds.
[0045] The above description is merely an optional embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A substrate support plate in a molecular beam epitaxy production apparatus, characterized in that, include: Base plate and graphite transition plate; The base plate is provided with a first through hole, and at least one first step is provided on the inner side of the first through hole; The graphite transition plate is made of graphite crystal material, and its outer side is provided with a second step that matches the first step. The graphite transition plate is embedded in the first through hole, and the second step is supported on the first step. The middle part of the graphite transition plate is provided with a second through hole. The inner side of the second through hole is provided with a wafer step for placing the substrate wafer, a ring step for placing the heat-blocking ring, and a limiting step for restricting the movement of the heat-blocking ring in sequence along an axial direction.
2. The substrate support plate in the molecular beam epitaxy production equipment according to claim 1, characterized in that, The inner sides of the wafer step, the annular step, and the limiting step are formed with circular holes whose radii increase sequentially and are arranged along the same axis.
3. The substrate support plate in the molecular beam epitaxy production equipment according to claim 1, characterized in that, The base plate is made of molybdenum.
4. The substrate support plate in the molecular beam epitaxy production equipment according to claim 1, characterized in that, The bottom support plate is evenly provided with four first through holes, and the graphite transition support plate is evenly provided with four second through holes.
5. The substrate support plate in the molecular beam epitaxy production equipment according to claim 1, characterized in that, The bottom support plate has a slot inside the first through hole, and the graphite transition support plate has a block on the outside. The block is engaged inside the slot to fix the bottom support plate and the graphite transition support plate in the circumferential direction of the first through hole.
6. The substrate support plate in the molecular beam epitaxy production equipment according to claim 5, characterized in that, The number of the card blocks is at least two, and they are evenly distributed along the circumference of the first through hole.