Molecular beam epitaxy device for preventing color change and slag falling of back surface of epitaxial wafer and application of molecular beam epitaxy device

Abstract

The invention provides a molecular beam epitaxy device for preventing color change and slag falling of the back surface of an epitaxial wafer and application. The molecular beam epitaxy device comprises a growth chamber; a carrying table is arranged in the growth chamber; a first step and a second step are sequentially arranged on the carrying table from bottom to top; a substrate is placed on the first step, and the back surface of the substrate faces the second step; and a shielding piece is placed on the second step. By optimizing the structure of the carrying table, the carrying table is sequentially provided with the first step and the second step from bottom to top, the first step and the second step are used for placing the substrate and the shielding piece respectively, the shielding piece is placed on the back face of the substrate for blocking, enrichment of As elements on the back face of an epitaxial wafer can be effectively reduced, epitaxial structure growth is carried out through the epitaxial device, and the yield of the epitaxial structure is improved. And obtaining the epitaxial wafer without discoloration and slag falling on the back surface.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing technology and relates to a molecular beam epitaxy device and its application for preventing discoloration and flaking on the back side of epitaxial wafers. Background Technology

[0002] Molecular beam epitaxy (MBE) is an advanced epitaxial growth technique that precisely controls the thickness and composition of thin films at the atomic level. It is widely used in the controllable fabrication of semiconductor quantum wells and heterojunction structures, such as InP, InAs, GaSb, GaAs, and their multi-element alloys. MBE growth chambers are typically equipped with multiple beam source furnaces. By precisely controlling the beam intensity, substrate temperature, and growth time, the desired epitaxial structure can be deposited layer by layer on the substrate surface.

[0003] In the process of growing epitaxial wafers via MBE, whether growing InAs / GaSb, AlAs / AlAsSb, or other materials on GaSb substrates, or growing In, Ga, Al, and As on indium phosphide substrates, the As source furnace provides the As2 / As4 beam. A stable and controllable beam value helps continuous growth, reduces defects during growth, and As beam protection also has a significant impact on the quality of the epitaxial wafer. Therefore, the As beam value is usually high, which causes a large number of As2 / As4 molecules to diffuse to the back of the sample holder and deposit or even oxidize on the back of the GaSb substrate. For InAs, GaSb, GaAs, and other substrates, the back is usually roughened by mechanical grinding or wet etching to improve thermal radiation absorption. However, the rough surface also provides more dangling bonds and defect sites, making it easier for As atoms to nucleate, aggregate, and form As-rich amorphous or polycrystalline layers on the back. When the thickness of the As-rich layer reaches tens of nanometers or more, its coefficient of thermal expansion becomes mismatched with the substrate. During cooling or wafer removal, it cracks and peels off due to thermo-mechanical stress, exhibiting a "flaking" phenomenon. These impurities not only contaminate the sample cassette, but the flaking residue also contaminates the front side of the epitaxial wafer. Simultaneously, As and its oxides have characteristic grayish-white, brownish-red, or iridescent colors, causing discoloration on the back side of the epitaxial wafer. If the flaking is severe, it will contaminate equipment such as microscopes and X-ray diffractometers during subsequent surface defect testing and compositional analysis of the grown epitaxial wafer after substrate removal, and will also adversely affect subsequent etching, photolithography, and other processes.

[0004] In summary, during the MBE (Metal-Based Epitaxial Grease) growth of epitaxial wafers, in addition to controlling the number and size of defects per unit area on the epitaxial wafer surface, it is also necessary to ensure that the back side of the epitaxial wafer does not discolor or flake. Therefore, obtaining an epitaxial wafer with no flakes or discoloration on the back side after growth is highly desirable. Summary of the Invention

[0005] The purpose of this invention is to provide a molecular beam epitaxy apparatus and its application for preventing discoloration and flaking on the back side of epitaxial wafers. By optimizing the stage structure and placing a shielding element on the back side of the substrate for isolation, the enrichment of As element on the back side of the epitaxial wafer can be effectively reduced. Using this epitaxial apparatus for epitaxial structure growth, an epitaxial wafer with no discoloration or flaking on the back side can be obtained.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a molecular beam epitaxy device for preventing discoloration and flaking on the back side of an epitaxial wafer, the molecular beam epitaxy device comprising a growth chamber;

[0008] The growth chamber is equipped with a platform; the platform is provided with a first step and a second step from bottom to top;

[0009] A substrate is placed on the first step, with the back side of the substrate facing the second step;

[0010] A shield is placed on the second step.

[0011] In this invention, the growth chamber of the molecular beam epitaxy apparatus is improved, while the other chambers remain unchanged.

[0012] The molecular beam epitaxy apparatus provided by this invention optimizes the stage structure. The stage is provided with a first step and a second step from bottom to top. The first step and the second step are used to place the substrate and the shielding member, respectively. The shielding member is placed on the back side of the substrate to block the accumulation of As element on the back side of the epitaxial wafer. Using this epitaxial apparatus to grow epitaxial structures, an epitaxial wafer with no discoloration and no flaking on the back side can be obtained.

[0013] Preferably, the length of the second step is greater than the length of the first step.

[0014] Preferably, the diameter of the shielding member is greater than or equal to the diameter of the substrate.

[0015] In this invention, in order to better and more completely shield the substrate, the diameter of the shielding element used must be greater than or equal to the diameter of the substrate.

[0016] Preferably, the height of the second step is greater than the height of the first step.

[0017] Preferably, the distance between the shielding member and the substrate is 0.4mm-3mm, for example, it can be 0.5mm, 0.6mm, 0.8mm, 1mm, 1.2mm, 1.4mm, 1.5mm, 1.6mm, 1.8mm, 2mm, 2.2mm, 2.4mm, 2.5mm, 2.6mm or 2.8mm, etc.

[0018] It should be noted that by setting the height of the second step to be greater than that of the first step, a certain gap can be made between the shielding component and the substrate, which facilitates the smooth removal of the epitaxial wafer after the epitaxial structure is grown. This avoids the situation where the shielding component and the epitaxial wafer are removed at the same time after the epitaxial structure is grown, which would lead to the problem of contamination on the front side of the epitaxial wafer.

[0019] Preferably, the thickness of the shielding member is 0.2mm-0.6mm, for example, it can be 0.25mm, 0.3mm, 0.35mm, 0.4mm, 0.454mm, 0.5mm or 0.55mm, and is preferably 0.2mm-0.4mm.

[0020] It should be noted that by adjusting the thickness of the shielding component within a specific range, it is more conducive to the conduction of heat in the form of thermal radiation, thus having a smaller impact on the growth process.

[0021] Preferably, the material of the shielding member includes any one or a combination of at least two of pyrolytic boron nitride, aluminum nitride, or aluminum oxide.

[0022] It should be noted that the selected shielding material has a wide bandgap, an extremely high melting point, and excellent thermal stability, which is more conducive to thermal radiation and ensures the normal growth of the epitaxial structure of the substrate.

[0023] Preferably, at least one side of the shielding member is polished.

[0024] In this invention, the side of the shielding member closest to the back of the substrate needs to be polished to prevent the shielding member from shedding during epitaxial growth, which would affect the quality of the epitaxial wafer.

[0025] Preferably, the platform is made of molybdenum and / or a molybdenum alloy.

[0026] Secondly, the present invention provides a method for preventing discoloration and chipping on the back side of an epitaxial wafer, wherein the method is performed using the molecular beam epitaxy apparatus described in the first aspect, and specifically includes:

[0027] The shielding component is cleaned and first dried and degassed in sequence. Then, the shielding component after the first drying and degassed is placed on the second step of the stage and second dried and degassed in the molecular beam epitaxy device. After that, the shielding component is removed.

[0028] The substrate and the second dried and degassed shielding member are placed sequentially on the first and second steps of the stage, and epitaxial growth is performed in the molecular beam epitaxy apparatus to obtain an epitaxial wafer with no discoloration or flaking on the back side.

[0029] In this invention, after cleaning and before the first drying and degassing, the process further includes wiping the shielding component with a lint-free cloth.

[0030] The method provided by this invention first involves cleaning and drying the shielding component to completely remove residual gases and volatile contaminants such as H2O, O2, and CO2 adsorbed on its surface. This prevents the introduction of impurities such as oxygen and carbon during epitaxial growth, ensuring the quality of the epitaxial wafer. Then, the substrate and the shielding component are grown together for epitaxial structure growth, resulting in an epitaxial wafer with no discoloration or flaking on the back side. This method is simple to operate, low in cost, and requires no adjustment of parameters related to the substrate epitaxial growth process.

[0031] Preferably, the cleaning solution used for cleaning includes an alcohol solvent and / or water.

[0032] In this invention, the alcohol solvent includes isopropanol, and the volume ratio of the alcohol solvent to water is 1:(15-25), for example, it can be 1:16, 1:17, 1:18, 1:19, 1:20, 1:21, 1:22, 1:23 or 1:24, etc.

[0033] Preferably, the cleaning method includes ultrasonic cleaning.

[0034] Preferably, the frequency of the ultrasonic cleaning is 15kHz-25kHz, for example, it can be 16kHz, 17kHz, 18kHz, 19kHz, 20kHz, 21kHz, 22kHz, 23kHz or 24kHz, etc.

[0035] Preferably, the temperature of the ultrasonic cleaning is 45℃-55℃, for example, it can be 46℃, 47℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃ or 54℃, etc.

[0036] Preferably, the ultrasonic cleaning time is 20-40 minutes, for example, it can be 22 minutes, 24 minutes, 25 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 35 minutes, 36 minutes or 38 minutes.

[0037] Preferably, the first drying and degassing is carried out in an oven.

[0038] Preferably, the temperature for the first drying and degassing is 180℃-220℃, for example, it can be 182℃, 185℃, 188℃, 190℃, 192℃, 195℃, 198℃, 200℃, 202℃, 205℃, 208℃, 210℃, 212℃, 215℃ or 218℃, etc.

[0039] Preferably, the first drying and degassing time is 20 min to 40 min, for example, it can be 22 min, 24 min, 25 min, 26 min, 28 min, 30 min, 32 min, 34 min, 35 min, 36 min or 38 min, etc.

[0040] Preferably, the second drying and degassing is carried out sequentially in the loading chamber, preparation chamber, and growth chamber of the molecular beam epitaxy apparatus.

[0041] Preferably, the temperature of the loading chamber is 100℃-150℃, for example, it can be 105℃, 110℃, 115℃, 120℃, 125℃, 130℃, 135℃, 140℃ or 145℃, etc.

[0042] Preferably, the temperature of the preparation chamber is 400℃-500℃, for example, it can be 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃ or 490℃, etc.

[0043] Preferably, the temperature of the growth chamber is 800℃-900℃, for example, it can be 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃ or 890℃, etc.

[0044] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The molecular beam epitaxy apparatus provided by the present invention optimizes the stage structure. The stage is provided with a first step and a second step from bottom to top. The first step and the second step are used to place the substrate and the shielding member, respectively. The shielding member is placed on the back side of the substrate to block the substrate. This can effectively reduce the enrichment of As element on the back side of the epitaxial wafer, thereby avoiding the occurrence of slag shedding and discoloration on the back side of the epitaxial wafer.

[0047] (2) The method provided by the present invention first cleans and dries the shielding component to remove residual gases such as H2O, O2, and CO2 and volatile pollutants adsorbed on the surface of the shielding component, so as to avoid introducing impurities such as oxygen and carbon during the epitaxial growth process and ensure the quality of the epitaxial wafer; then the substrate and the shielding component are grown together to obtain an epitaxial wafer with no discoloration and no flaking on the back side. Attached Figure Description

[0048] Figure 1 A schematic diagram of the platform provided in Example 1;

[0049] Wherein, 1-first step, 2-second step.

[0050] Figure 2 This is a schematic diagram of the shielding component after processing in step (1) in Application Example 1.

[0051] Figure 3 This is a schematic diagram of the back side of the epitaxial wafer obtained in Application Example 1.

[0052] Figure 4 A schematic diagram of the back side of the epitaxial wafer obtained in Application Example 1 is shown for comparison. Detailed Implementation

[0053] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0054] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0056] Example 1

[0057] This embodiment provides a molecular beam epitaxy device for preventing discoloration and chipping on the back side of an epitaxial wafer, the molecular beam epitaxy device including a growth chamber;

[0058] The growth chamber is equipped with a platform (such as...) Figure 1 (As shown); the platform is made of molybdenum; the platform is provided with a first step 1 and a second step 2 from bottom to top; the length of the second step 2 is greater than the length of the first step 1; the height of the second step 2 is greater than the height of the first step 1;

[0059] A substrate is placed on the first step 1, with the back side of the substrate facing the second step 2; the substrate is a GaSb substrate with a diameter of 50.8 mm and a thickness of 0.5 mm;

[0060] A shielding component is placed on the second step 2; the shielding component is a double-polished Al2O3 material with a diameter of 52mm and a thickness of 0.4mm;

[0061] The distance between the shielding element and the substrate is 0.6 mm.

[0062] Example 2

[0063] This embodiment provides a molecular beam epitaxy device for preventing discoloration and chipping on the back side of an epitaxial wafer, the molecular beam epitaxy device including a growth chamber;

[0064] The growth chamber is equipped with a platform; the platform is made of molybdenum; the platform has a first step and a second step arranged from bottom to top; the length of the second step is greater than the length of the first step; the height of the second step is greater than the height of the first step;

[0065] A substrate is placed on the first step, with the back side of the substrate facing the second step; the substrate is a GaAs substrate with a diameter of 50.8 mm and a thickness of 0.35 mm;

[0066] A shielding element is placed on the second step; the shielding element is a single-polished Al2O3 material with a diameter of 50.8 mm and a thickness of 0.2 mm; the side of the shielding element near the back of the substrate is polished.

[0067] The distance between the shielding element and the substrate is 0.8 mm.

[0068] Example 3

[0069] This embodiment provides a molecular beam epitaxy device for preventing discoloration and chipping on the back side of an epitaxial wafer, the molecular beam epitaxy device including a growth chamber;

[0070] The growth chamber is equipped with a platform; the platform is made of molybdenum; the platform has a first step and a second step arranged from bottom to top; the length of the second step is greater than the length of the first step; the height of the second step is greater than the height of the first step;

[0071] A substrate is placed on the first step, with the back side of the substrate facing the second step; the substrate is a GaAs substrate with a diameter of 50.8 mm and a thickness of 0.5 mm.

[0072] A shielding component is placed on the second step; the shielding component is a double-polished Al2O3 material with a diameter of 53mm and a thickness of 0.6mm;

[0073] The distance between the shielding element and the substrate is 0.6 mm.

[0074] Example 4

[0075] This embodiment provides a molecular beam epitaxy device for preventing discoloration and flaking on the back side of an epitaxial wafer. Except that the height of the second step is less than the height of the first step, i.e., the distance between the shielding member and the substrate is 0 mm, all other conditions are the same as in Embodiment 1.

[0076] Example 5

[0077] This embodiment provides a molecular beam epitaxy device for preventing discoloration and chipping on the back side of an epitaxial wafer. Except for the distance between the shielding member and the substrate being 5 mm, all other conditions are the same as in Embodiment 1.

[0078] Example 6

[0079] This embodiment provides a molecular beam epitaxy device to prevent discoloration and flaking on the back side of an epitaxial wafer. Except that the shielding member is made of double-polished boron nitride material, all other conditions are the same as in Embodiment 1.

[0080] Example 7

[0081] This embodiment provides a molecular beam epitaxy device to prevent discoloration and flaking on the back side of an epitaxial wafer. Except that the shielding member is made of Al2O3 material that has not been polished on both sides, all other conditions are the same as in Embodiment 1.

[0082] Example 8

[0083] This embodiment provides a molecular beam epitaxy device for preventing discoloration and flaking on the back side of an epitaxial wafer. Except that the stage is made of silicon, all other conditions are the same as in Embodiment 1.

[0084] Comparative Example 1

[0085] This comparative example provides a molecular beam epitaxy device for preventing discoloration and chipping on the back side of an epitaxial wafer. Except for the absence of a shielding element on the second step, all other conditions are the same as in Example 1.

[0086] Application Example 1

[0087] This application example provides a method for preventing discoloration and chipping on the back side of an epitaxial wafer. The method is performed using the molecular beam epitaxy apparatus provided in Example 1, and specifically includes:

[0088] (1) The shielding component is sequentially cleaned, wiped with a lint-free cloth, and subjected to a first drying and degassing process. Then, the shielding component after the first drying and degassing is placed on the second step of the stage, and subjected to a second drying and degassing process in the molecular beam epitaxy apparatus. Afterward, the shielding component is removed (e.g., ...). Figure 2 (as shown)

[0089] The cleaning solution is isopropanol and water in a volume ratio of 1:20; the cleaning method is ultrasonic cleaning; the ultrasonic cleaning frequency is 20kHz, the temperature is 50℃, and the time is 30min; the first drying and degassing is carried out in an oven; the temperature of the first drying and degassing is 200℃, and the time is 30min.

[0090] The second drying and degassing process is carried out sequentially in a loading chamber at 120°C for 2200s, a preparation chamber at 450°C for 3600s, and a growth chamber at 850°C for 10800s.

[0091] (2) The substrate and the second dried and degassed shielding member are placed sequentially on the first and second steps of the stage, and epitaxial growth is performed under a molecular beam epitaxy device and an As source to obtain an epitaxial wafer with no discoloration or flaking on the back side (e.g. Figure 3 (As shown).

[0092] Application Example 2

[0093] This application example provides a method for preventing discoloration and chipping on the back side of an epitaxial wafer. The method is performed using the molecular beam epitaxy apparatus provided in Example 2, and specifically includes:

[0094] (1) The shielding component is cleaned, wiped with a lint-free cloth and dried and degassed in sequence. Then the shielding component after the first drying and degassed is placed on the second step of the stage and dried and degassed in the molecular beam epitaxy device. Then the shielding component is removed.

[0095] The cleaning solution is isopropanol and water in a volume ratio of 1:25; the cleaning method is ultrasonic cleaning; the ultrasonic cleaning frequency is 15kHz, the temperature is 55℃, and the time is 20min; the first drying and degassing is carried out in an oven; the temperature of the first drying and degassing is 220℃, and the time is 20min.

[0096] The second drying and degassing process is carried out sequentially in a loading chamber at 100°C for 2800s, a preparation chamber at 420°C for 3600s, and a growth chamber at 820°C for 10800s.

[0097] (2) The substrate and the second dried and degassed shielding member are placed sequentially on the first step and the second step of the stage, and epitaxial growth is performed under the molecular beam epitaxy device and the As source to obtain an epitaxial wafer with no discoloration or flaking on the back side.

[0098] Application Example 3

[0099] This application example provides a method for preventing discoloration and chipping on the back side of an epitaxial wafer. The method is performed using the molecular beam epitaxy apparatus provided in Example 3, and specifically includes:

[0100] (1) The shielding component is cleaned, wiped with a lint-free cloth and dried and degassed in sequence. Then the shielding component after the first drying and degassed is placed on the second step of the stage and dried and degassed in the molecular beam epitaxy device. Then the shielding component is removed.

[0101] The cleaning solution is isopropanol and water in a volume ratio of 1:15; the cleaning method is ultrasonic cleaning; the ultrasonic cleaning frequency is 25kHz, the temperature is 45℃, and the time is 40min; the first drying and degassing is carried out in an oven; the temperature of the first drying and degassing is 180℃, and the time is 40min.

[0102] The second drying and degassing process is carried out sequentially in a loading chamber at 150°C for 2000s, a preparation chamber at 480°C for 3600s, and a growth chamber at 880°C for 10800s.

[0103] (2) The substrate and the second dried and degassed shielding member are placed sequentially on the first step and the second step of the stage, and epitaxial growth is performed under the molecular beam epitaxy device and the As source to obtain an epitaxial wafer with no discoloration or flaking on the back side.

[0104] Application Example 4-8

[0105] Application Examples 4-8 provide a method for preventing discoloration and chipping on the back side of an epitaxial wafer. Except that the method is performed using the molecular beam epitaxy apparatus provided in Examples 4-8, all other conditions are the same as in Application Example 1.

[0106] Comparative Application Example 1

[0107] This comparative application example provides a method for preventing discoloration and chipping on the back side of an epitaxial wafer. Except that the method is performed using the molecular beam epitaxy apparatus provided in Comparative Example 1, all other conditions are the same as in Application Example 1.

[0108] A schematic diagram of the back side of the epitaxial wafer obtained in this comparative application example is shown below. Figure 4 As shown. By Figure 3-4 The comparison shows that by placing the shielding element on the back side of the substrate to block it, the enrichment of As elements on the back side of the epitaxial wafer can be effectively reduced, thereby avoiding the occurrence of flaking and discoloration problems on the back side of the epitaxial wafer.

[0109] The appearance results of the epitaxial wafers obtained from the above application examples and comparative application examples are shown in Table 1 and... Figure 3-4 As shown.

[0110] Table 1

[0111]

[0112] As shown in Table 1:

[0113] The molecular beam epitaxy apparatus and method provided by this invention optimizes the stage structure and places a shielding element on the back side of the substrate for isolation. Combined with pretreatment of the shielding element, the enrichment of As element on the back side of the epitaxial wafer can be effectively reduced. Using this epitaxial apparatus to grow epitaxial structures, an epitaxial wafer with no discoloration and no flaking on the back side can be obtained.

[0114] A comparison of Application Examples 1 and 4-5 reveals that when the shielding element is in contact with the substrate, it adheres to the epitaxial wafer due to air pressure. When the suction pen picks up the shielding element, it simultaneously lifts both the shielding element and the epitaxial wafer. Subsequently, the epitaxial wafer falls due to gravity, resulting in contamination of its front side. If the distance between the shielding element and the substrate is too large, poor heat transfer prevents the heat from the substrate heater from being effectively transferred to the substrate after passing through the shielding element, thus affecting the quality of the grown material.

[0115] A comparison of Application Example 1 and Application Examples 6-7 shows that if the shielding component is made of non-pyrolytic boron nitride, although an epitaxial wafer with no discoloration or slag on the back side can be obtained, it is expensive and increases production costs. If the surface of the shielding component is not polished, due to the large surface roughness of the shielding component, slag may occur during epitaxial growth, contaminating the epitaxial wafer.

[0116] A comparison of Application Example 1 and Application Example 8 shows that if a silicon stage is used, silicon is a brittle material that is prone to cracking under high temperature and thermal stress. Furthermore, silicon vapor or other byproducts are easily released into the process chamber at high temperatures, leading to contamination of the epitaxial wafer.

[0117] A comparison of Application Example 1 and Comparative Application Example 1 shows that if no shielding is provided, the As source diffuses to the back of the stage and deposits or oxidizes on the back of the substrate, causing discoloration and flaking on the back of the epitaxial wafer.

[0118] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A molecular beam epitaxy device for preventing discoloration and flaking on the back side of epitaxial wafers, characterized in that, The molecular beam epitaxy apparatus includes a growth chamber; The growth chamber is equipped with a platform; the platform is provided with a first step and a second step from bottom to top; A substrate is placed on the first step, with the back side of the substrate facing the second step; A shield is placed on the second step.

2. The molecular beam epitaxy apparatus according to claim 1, characterized in that, The length of the second step is greater than the length of the first step; Preferably, the diameter of the shielding member is greater than or equal to the diameter of the substrate.

3. The molecular beam epitaxy apparatus according to claim 1, characterized in that, The height of the second step is greater than the height of the first step; Preferably, the distance between the shielding member and the substrate is 0.4mm-3mm.

4. The molecular beam epitaxy apparatus according to claim 1, characterized in that, The thickness of the shielding element is 0.2mm-0.6mm, preferably 0.2mm-0.4mm.

5. The molecular beam epitaxy apparatus according to claim 1, characterized in that, The material of the shielding component includes any one or a combination of at least two of pyrolytic boron nitride, aluminum nitride, or aluminum oxide.

6. The molecular beam epitaxy apparatus according to claim 1, characterized in that, At least one side of the shielding member is polished.

7. The molecular beam epitaxy apparatus according to claim 1, characterized in that, The platform is made of molybdenum and / or molybdenum alloys.

8. A method for preventing discoloration and chipping on the back side of an epitaxial wafer, characterized in that, The method is performed using the molecular beam epitaxy apparatus according to any one of claims 1-7, specifically including: The shielding component is cleaned and first dried and degassed in sequence. Then, the shielding component after the first drying and degassed is placed on the second step of the stage and second dried and degassed in the molecular beam epitaxy device. After that, the shielding component is removed. The substrate and the second dried and degassed shielding member are placed sequentially on the first and second steps of the stage, and epitaxial growth is performed in the molecular beam epitaxy apparatus to obtain an epitaxial wafer with no discoloration or flaking on the back side.

9. The method according to claim 8, characterized in that, The cleaning solution used for cleaning includes alcohol solvents and / or water; Preferably, the cleaning method includes ultrasonic cleaning; Preferably, the frequency of the ultrasonic cleaning is 15kHz-25kHz; Preferably, the temperature of the ultrasonic cleaning is 45℃-55℃; Preferably, the ultrasonic cleaning time is 20-40 minutes; Preferably, the first drying and degassing is carried out in an oven; Preferably, the temperature for the first drying and degassing is 180℃-220℃; Preferably, the first drying and degassing time is 20 min to 40 min.

10. The method according to claim 8, characterized in that, The second drying and degassing process is carried out sequentially in the loading chamber, preparation chamber, and growth chamber of the molecular beam epitaxy apparatus; Preferably, the temperature of the loading chamber is 100℃-150℃; Preferably, the temperature of the preparation chamber is 400℃-500℃; Preferably, the temperature of the growth chamber is 800℃-900℃.

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