Substrate Deoxidation Method and Molecular Beam Epitaxial Growth Method of Semiconductor Device
By real-time detection of the diffraction stripe brightness of the substrate and establishing a relationship matrix, the problem of accurate judgment of the substrate deoxygenation completion point is solved, and the quality and production efficiency of the epitaxial sheet are improved.
Patent Information
- Application Number
- CN202410827770.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-25
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2044-06-25
AI Technical Summary
The prior art is difficult to accurately determine whether the substrate is just completed deoxygenation, resulting in defects after epitaxial growth.
By detecting the diffraction stripe brightness of the substrate in real time, k epitaxial sheets are formed during the substrate deoxidation process, and a relationship matrix between defect density and diffraction stripe brightness is established, and the diffraction stripe brightness corresponding to the lowest defect density is determined as the deoxygenation completion point.
Accurately determining whether the substrate is just deoxygenated, improves the production quality of epitaxial sheets, reduces the density of surface defects, is suitable for substrates from different manufacturers and batches, and improves the repeatability and yield of mass production.
Smart Images
Figure CN118756329B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor integrated circuit manufacturing, and particularly to a method for deoxidizing a substrate and a method for molecular beam epitaxial growth of a semiconductor device. Background Art
[0002] When preparing a semiconductor device (such as an InP-based semiconductor device) by using a molecular beam epitaxy process, it is first necessary to perform a high-temperature deoxidation treatment on the substrate to remove the oxide layer on the substrate surface, and then grow an epitaxial layer on the substrate.
[0003] Among them, when performing a high-temperature deoxidation treatment on the substrate, it is necessary to control the deoxidation time and the deoxidation temperature; if the deoxidation time is too short, the oxide layer will not be completely removed, which will lead to the formation of type I defects (i.e., protrusion defects) after epitaxial growth; if the deoxidation time is too long or the deoxidation temperature is too high, the phosphorus on the substrate surface will desorb, resulting in the formation of type II defects (i.e., depression defects) after epitaxial growth. Therefore, during the deoxidation process, a reflection high-energy electron diffraction instrument (RHEED, reflection high-energy electron diffraction) is used to monitor the substrate surface in real time. As the deoxidation degree of the substrate surface is different, different diffraction fringe patterns will be formed in the RHEED system. However, it is difficult to accurately judge whether the substrate is just deoxidized completely by observing the difference in the diffraction fringe patterns with the naked eye in a conventional manner.
[0004] Therefore, how to accurately judge the deoxidation degree of the substrate is an urgent problem to be solved. Summary of the Invention
[0005] The purpose of the present invention is to provide a method for deoxidizing a substrate and a method for molecular beam epitaxial growth of a semiconductor device, so as to be able to accurately judge whether the substrate is just deoxidized completely.
[0006] To achieve the above purpose, the present invention provides a method for deoxidizing a substrate, including:
[0007] Providing k substrates, with an oxide layer formed on the surface of the substrates;
[0008] Deoxidizing the substrates to remove the oxide layer on the surface of the substrates; and, during the deoxidation process, detecting the brightness of the diffraction fringes of the substrates in real time, so that the k substrates end deoxidation with different diffraction fringe brightnesses; where k is an integer greater than or equal to 5;
[0009] Using a molecular beam epitaxial growth method to form an epitaxial layer on the deoxidized substrates to form k epitaxial wafers;
[0010] Performing a surface topography characterization test on the epitaxial wafers to obtain the defect density on the surfaces of the k epitaxial wafers;
[0011] A relationship matrix is established based on the defect density of the k epitaxial wafers and the diffraction fringe brightness of the k substrates, so as to obtain the diffraction fringe brightness corresponding to the lowest defect density according to the relationship matrix, and use the diffraction fringe brightness corresponding to the lowest defect density as the deoxidation completion point of the substrate to be deoxidized.
[0012] Optionally, the material of the substrate is InP, InAs or InSb.
[0013] Optionally, the thicknesses of the oxide layers on the surfaces of the k substrates are the same or different.
[0014] Optionally, the defects on the surface of the epitaxial wafer include protrusions and depressions.
[0015] Optionally, before deoxidizing the substrate, the substrate deoxidation method further includes:
[0016] Providing a substrate sample;
[0017] Deoxidizing the substrate sample, and detecting the change in the diffraction fringe brightness of the substrate sample in real time during the deoxidation process;
[0018] Taking the lowest value of the diffraction fringe brightness of the substrate sample as the reference brightness to calibrate the diffraction fringe brightness of the k substrates.
[0019] Optionally, the same preset As pressure and the same preset deoxidation temperature are used when deoxidizing the substrate and deoxidizing the substrate sample.
[0020] Optionally, the diffraction fringe brightness of the substrate refers to the diffraction fringe brightness of a specific area on the surface of the substrate, the diffraction fringe brightness of the substrate sample refers to the diffraction fringe brightness of a specific area on the surface of the substrate sample, and the position of the diffraction fringes in the specific area remains unchanged.
[0021] Optionally, the steps of detecting the diffraction fringe brightness of the substrate and the substrate sample include:
[0022] Using a reflection high energy electron diffractometer to form diffraction fringe patterns on the surfaces of the substrate and the substrate sample;
[0023] Using an image analyzer to analyze the diffraction fringe patterns to obtain the diffraction fringe brightness.
[0024] The present invention also provides a molecular beam epitaxial growth method for a semiconductor device, including:
[0025] Obtaining the deoxidation completion point of the substrate to be deoxidized by using the substrate deoxidation method described above;
[0026] Deoxygenate the substrate to be deoxygenated, and during the deoxygenation process, detect the brightness of the diffraction fringes of the substrate to be deoxygenated in real time, so as to stop deoxygenation when the brightness of the diffraction fringes of the substrate to be deoxygenated reaches the deoxygenation completion point;
[0027] Use molecular beam epitaxy growth method to form an epitaxial layer on the deoxygenated substrate to be deoxygenated.
[0028] Optionally, deoxygenate multiple substrates to be deoxygenated, and the thicknesses of the oxide layers on the surfaces of the multiple substrates to be deoxygenated are the same or different.
[0029] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:
[0030] 1. In the substrate deoxygenation method of the present invention, since it includes: providing k substrates, an oxide layer is formed on the surface of the substrates; deoxygenating the substrates to remove the oxide layer on the surface of the substrates; and during the deoxygenation process, detecting the brightness of the diffraction fringes of the substrates in real time, so that the k substrates end deoxygenation with different diffraction fringe brightnesses; where k is an integer greater than or equal to 5; use molecular beam epitaxy growth method to form an epitaxial layer on the deoxygenated substrates to form k epitaxial wafers; perform surface topography characterization tests on the epitaxial wafers to obtain the defect densities on the surfaces of the k epitaxial wafers; establish a relationship matrix based on the defect densities of the k epitaxial wafers and the diffraction fringe brightnesses of the k substrates, so as to obtain the diffraction fringe brightness corresponding to the lowest defect density according to the relationship matrix, and use the diffraction fringe brightness corresponding to the lowest defect density as the deoxygenation completion point of the substrate to be deoxygenated, so that it is possible to accurately judge whether the substrate is just deoxygenated completely.
[0031] 2. In the molecular beam epitaxy growth method of the semiconductor device of the present invention, since the deoxygenation completion point of the substrate to be deoxygenated is obtained by using the substrate deoxygenation method described above; deoxygenate the substrate to be deoxygenated, and during the deoxygenation process, detect the brightness of the diffraction fringes of the substrate to be deoxygenated in real time, so as to stop deoxygenation when the brightness of the diffraction fringes of the substrate to be deoxygenated reaches the deoxygenation completion point; use molecular beam epitaxy growth method to form an epitaxial layer on the deoxygenated substrate to be deoxygenated, so that it is possible to accurately judge whether the substrate is just deoxygenated completely, and improve the production quality of the epitaxial wafers. Description of the Drawings
[0032] Figure 1 is a flowchart of the substrate deoxygenation method according to an embodiment of the present invention;
[0033] Figures 2a to 2d is a reflection high energy electron diffraction pattern of a substrate according to an embodiment of the present invention;
[0034] Figure 3It is a trend graph of the defect density varying with the brightness of diffraction fringes in an embodiment of the present invention. Detailed implementation manners
[0035] To make the objectives, advantages and features of the present invention clearer, the following further describes in detail the substrate deoxidation method and the molecular beam epitaxial growth method of semiconductor devices proposed by the present invention. It should be noted that the drawings are all in very simplified forms and use non-precise scales, only for conveniently and clearly assisting in explaining the objectives of the embodiments of the present invention.
[0036] An embodiment of the present invention provides a substrate deoxidation method. Referring to Figure 1 , from Figure 1 it can be seen that the substrate deoxidation method includes:
[0037] Step S1: Provide k substrates, and an oxide layer is formed on the surface of the substrates;
[0038] Step S2: Deoxidize the substrates to remove the oxide layer on the surface of the substrates; and during the deoxidation process, the brightness of the diffraction fringes of the substrates is detected in real time, so that the k substrates end deoxidation with different diffraction fringe brightnesses; where k is an integer greater than or equal to 5;
[0039] Step S3: Use the molecular beam epitaxial growth method to form an epitaxial layer on the deoxidized substrates to form k epitaxial wafers;
[0040] Step S4: Perform surface topography characterization tests on the epitaxial wafers to obtain the defect densities on the surfaces of the k epitaxial wafers;
[0041] Step S5: Establish a relationship matrix based on the defect densities of the k epitaxial wafers and the brightness of the diffraction fringes of the k substrates, so as to obtain the brightness of the diffraction fringes corresponding to the lowest defect density according to the relationship matrix, and use the brightness of the diffraction fringes corresponding to the lowest defect density as the deoxidation completion point of the substrates to be deoxidized.
[0042] Next, refer to FIGS. 2 to Figure 3 The substrate deoxidation method provided in this embodiment will be described in detail.
[0043] According to step S1, k substrates are provided, and an oxide layer is formed on the surface of the substrates.
[0044] The material of the substrates is InP, InAs or InSb.
[0045] The oxide layer is the natural oxide formed on the surface of the substrates.
[0046] The thicknesses of the oxide layers on the surfaces of the k substrates are the same or different.
[0047] According to step S2, the substrate is deoxidized to remove the oxide layer on the surface of the substrate; and during the deoxidation process, the brightness of the diffraction fringes of the substrate is detected in real time, so that k substrates end deoxidation with different brightnesses of diffraction fringes; where k is an integer greater than or equal to 5.
[0048] When k substrates end deoxidation, the degree of deoxidation of the k substrates is different, so that when deoxidation ends, the k substrates have different brightnesses of diffraction fringes.
[0049] Among them, when deoxidation ends, the oxide layer on the surface of some of the substrates may not be completely removed (i.e., deoxidation is not completed), the oxide layer on the surface of a certain substrate may be just completely removed (i.e., deoxidation is just completed), and the oxide layer on the surface of the remaining part of the substrates may be completely removed and continue to be deoxidized after complete removal (i.e., over-deoxidation).
[0050] In one embodiment, when deoxidation ends, the brightness of the diffraction fringes of the k substrates may gradually increase, where the increase value of the brightness of the diffraction fringes between two adjacent substrates may be the same or different.
[0051] Preferably, before deoxidizing the substrate, the substrate deoxidation method further includes: first, providing a substrate sample, and an oxide layer is also formed on the surface of the substrate sample; then, deoxidizing the substrate sample, and detecting the change in the brightness of the diffraction fringes of the substrate sample in real time during the deoxidation process; then, taking the lowest value of the brightness of the diffraction fringes of the substrate sample as the reference brightness for calibrating the brightness of the diffraction fringes of the k substrates.
[0052] The steps of detecting the brightness of the diffraction fringes of the substrate and the substrate sample may include: first, using a reflection high-energy electron diffraction instrument (RHEED, reflection high-energy electron diffraction) to form a diffraction fringe pattern on the surfaces of the substrate and the substrate sample; then, using an image analyzer to analyze the diffraction fringe pattern to obtain the brightness of the diffraction fringes.
[0053] Among them, the reflection high-energy electron diffraction instrument includes a high-energy electron gun and a fluorescent screen. The high-energy electron beam emitted by the high-energy electron gun reaches the surfaces of the substrate and the substrate sample at a very small angle. The high-energy electron beam penetrates into one to two atomic layers away from the surfaces of the substrate and the substrate sample. The diffracted electron beam hits the fluorescent screen to form a diffraction fringe pattern, and the diffraction fringe pattern includes multiple diffraction fringes; the image analyzer is connected to the fluorescent screen, and the image analyzer can extract the diffraction fringe pattern on the fluorescent screen and analyze the diffraction fringe pattern to obtain the brightness of the diffraction fringes.
[0054] It should be noted that an image analyzer well-known or commonly used in the art can be adopted.
[0055] When detecting the diffraction fringe brightness of different substrates, there may be certain factors (such as the placement position of different substrates being offset, or there being slight differences in the number of high-energy electron beams emitted by the high-energy electron gun to the surfaces of different substrates, etc.) that cause the diffraction fringe brightness detected for different substrates with the same degree of deoxidation to be different. Therefore, in order to exclude the influence of the above factors on the detection result of the diffraction fringe brightness of the substrate, the substrate sample is used to calibrate the reflection high-energy electron diffractometer, that is, the lowest value of the diffraction fringe brightness of the substrate sample during the deoxidation process is used as the reference brightness, which is used to calibrate the diffraction fringe brightness of the k substrates and the diffraction fringe brightness of the substrate to be deoxidized subsequently.
[0056] The same preset As pressure and the same preset deoxidation temperature are adopted when deoxidizing the substrate and when deoxidizing the substrate sample. Among them, the preset As pressure and the preset deoxidation temperature can select appropriate ranges according to the material types of the substrate and the oxide layer and the process requirements.
[0057] Preferably, the diffraction fringe brightness of the substrate refers to the diffraction fringe brightness of a specific area on the surface of the substrate, the diffraction fringe brightness of the substrate sample refers to the diffraction fringe brightness of a specific area on the surface of the substrate sample, and the position of the diffraction fringes in the specific area remains unchanged, that is, as the degree of deoxidation of the substrate and the substrate sample changes, only the brightness of the diffraction fringes in the specific area changes.
[0058] Since the positions of the diffraction fringes in the specific area remain unchanged, using the diffraction fringe brightness in the specific area as the diffraction fringe brightness of the entire surface of the substrate and the substrate sample can exclude the influence of regional position changes on the diffraction fringe brightness of the substrate and the substrate sample.
[0059] In one embodiment, the diffraction fringes in the specific area include two main fringes and three secondary fringes, and the three secondary fringes are sequentially and spacedly arranged between the two main fringes; as the deoxidation time increases, the brightness of the two main fringes gradually increases, and the brightness of the three secondary fringes first gradually decreases and then gradually increases.
[0060] As Figures 2a to 2d shown, in the specific area A1, the two main fringes B1 and the three secondary fringes B2 extend in the first direction, the two main fringes B1 and the three secondary fringes B2 are spacedly arranged in the second direction, the three secondary fringes B2 are sequentially and spacedly arranged between the two main fringes B1, and the first direction is perpendicular to the second direction; Figure 2a and Figure 2bThe diffraction fringes shown all correspond to the case where the substrate has not completed deoxidation, and Figure 2b the degree of deoxidation of the substrate corresponding to the diffraction fringes shown is greater than Figure 2a the degree of deoxidation of the substrate corresponding to the diffraction fringes shown, Figure 2c the diffraction fringes shown correspond to the case where the substrate has just completed deoxidation, Figure 2d the diffraction fringes shown correspond to the case where the substrate has been over-deoxidized. Therefore, from Figures 2a to 2d it can be seen that as the deoxidation time increases, the brightness of the two main fringes B1 gradually increases, the brightness of the middle one of the three secondary fringes B2 first decreases, and then the three secondary fringes B2 appear simultaneously (i.e., the brightness changes from dark to bright), and then the brightness of the three secondary fringes B2 gradually increases.
[0061] According to step S3, an epitaxial layer is formed on the deoxidized substrate by molecular beam epitaxy to form k epitaxial wafers.
[0062] Among them, when forming the epitaxial layer, the thickness of the epitaxial layer needs to be controlled so that after forming the epitaxial layer, all or most of the defects can be revealed on the surface of the epitaxial wafer.
[0063] According to step S4, surface topography characterization tests are performed on the epitaxial wafers to obtain the defect density on the surfaces of the k epitaxial wafers.
[0064] Among them, a surface defect scanner can be used to scan the surface of the epitaxial wafer for defects and count the defect density on the surface of the epitaxial wafer.
[0065] It should be noted that a surface defect scanner well-known or commonly used in the art can be used.
[0066] Surface topography characterization tests can be performed on the entire surface of the epitaxial wafer, that is, the defect density on the entire surface of the epitaxial wafer is obtained. It should be noted that the defect density in different regions on the surface of the epitaxial wafer is uniform.
[0067] The defects on the surface of the epitaxial wafer include all types of defects on the surface of the epitaxial wafer, including defects such as protrusions and depressions.
[0068] According to step S5, a relationship matrix is established based on the defect density of the k epitaxial wafers and the diffraction fringe brightness of the k substrates, so as to obtain the diffraction fringe brightness corresponding to the lowest defect density according to the relationship matrix, and use the diffraction fringe brightness corresponding to the lowest defect density as the deoxidation completion point of the substrate to be deoxidized.
[0069] Wherein, the deoxidation completion point refers to that when deoxidizing the substrate to be deoxidized, when the brightness of the diffraction fringes of the substrate to be deoxidized reaches the brightness of the diffraction fringes corresponding to the lowest defect density, the oxide layer on the surface of the substrate to be deoxidized is just completely removed, that is, the deoxidation is just completed.
[0070] Wherein, the relationship matrix established according to the defect densities of the k epitaxial wafers and the brightnesses of the diffraction fringes of the corresponding k substrates can obtain the corresponding calculation model between the defect density of the epitaxial wafer and the brightness of the diffraction fringes of the substrate, so as to simulate and obtain the brightness of the diffraction fringes corresponding to the lowest defect density according to the calculation model.
[0071] For Figure 3 example, in a coordinate system, with the brightness of the diffraction fringes as the abscissa and the defect density as the ordinate, the data of the defect densities of k groups and the data of the corresponding brightnesses of the diffraction fringes are marked in the coordinate system to simulate the trend graph of the change of the defect density with the brightness of the diffraction fringes and simulate and obtain the calculation model.
[0072] Since when the substrate is just deoxidized, the defect density on the surface of the epitaxial wafer is the lowest; compared with when the substrate is just deoxidized, the defect density on the surface of the epitaxial wafer will increase when the substrate is not completely deoxidized and over-deoxidized, therefore, the brightness of the diffraction fringes corresponding to the lowest defect density can be used as the deoxidation completion point of the substrate to be deoxidized.
[0073] As can be seen from the above, by establishing a relationship matrix based on the defect density of the k epitaxial wafers and the diffraction fringe brightness of the k substrates, obtaining the diffraction fringe brightness corresponding to the lowest defect density according to the relationship matrix, and using the diffraction fringe brightness corresponding to the lowest defect density as the deoxidation completion point of the substrate to be deoxidized, when subsequently deoxidizing the substrate to be deoxidized, it is only necessary to detect whether the diffraction fringe brightness of the substrate to be deoxidized reaches the diffraction fringe brightness corresponding to the lowest defect density to accurately determine whether the deoxidation is just completed, avoiding incomplete deoxidation or over-deoxidation, improving the accuracy of judging whether the deoxidation is just completed, and also reducing the surface defect density after forming an epitaxial layer on the substrate to be deoxidized, improving the production quality of the epitaxial wafer; moreover, the thickness of the oxide layer on the substrates to be deoxidized provided by different manufacturers is different, and the thickness of the oxide layer on the substrates to be deoxidized in different batches provided by the same manufacturer is also different. Therefore, when deoxidizing these substrates to be deoxidized, the deoxidation time required for just completing the deoxidation is not the same. In the present invention, it is only necessary to detect whether the diffraction fringe brightness of the substrate to be deoxidized reaches the diffraction fringe brightness corresponding to the lowest defect density to accurately determine whether the deoxidation is just completed, without considering the factors of deoxidation time and oxide layer thickness, having wide applicability; and since it is possible to accurately determine whether the deoxidation is just completed when deoxidizing the substrates to be deoxidized provided by different manufacturers and different batches, it is beneficial to ensure repeatability and improve the yield during the batch production of the epitaxial wafers.
[0074] In addition, when deoxidizing the substrate to be deoxidized, the substrate to be deoxidized is placed on a carrier plate, and the deoxidation of the substrate to be deoxidized is achieved by baking the substrate to be deoxidized through a heating component in the carrier plate. However, when the heating components in different carrier plates are set at the same baking temperature (i.e., the same deoxidation temperature is set), there will be a difference in the actual temperature of different carrier plates, resulting in different actual deoxidation temperatures of the substrates to be deoxidized on different carrier plates. As a result, even if the thickness of the oxide layer on the surfaces of the substrates to be deoxidized on different carrier plates is the same, the deoxidation time required for just completing the deoxidation of the substrates to be deoxidized on different carrier plates is not the same. Therefore, it is also inaccurate to judge whether the deoxidation is just completed for multiple substrates to be deoxidized with the same oxide layer thickness by the same deoxidation time. In the present invention, it is only necessary to detect whether the diffraction fringe brightness of the substrate to be deoxidized reaches the diffraction fringe brightness corresponding to the lowest defect density to accurately determine whether the substrates to be deoxidized on all different carrier plates are just deoxidized, avoiding the influence of the difference in actual deoxidation temperature on the judgment of deoxidation completion.
[0075] In summary, the substrate deoxidation method provided by the present invention includes: providing k substrates, an oxide layer being formed on the surface of the substrates; deoxidizing the substrates to remove the oxide layer on the surface of the substrates; and, during the deoxidation process, detecting the brightness of the diffraction fringes of the substrates in real time, so that the k substrates end the deoxidation with different diffraction fringe brightnesses; where k is an integer greater than or equal to 5; forming an epitaxial layer on the deoxidized substrates by using a molecular beam epitaxy growth method to form k epitaxial wafers; performing a surface topography characterization test on the epitaxial wafers to obtain the defect density on the surfaces of the k epitaxial wafers; establishing a relationship matrix based on the defect densities of the k epitaxial wafers and the diffraction fringe brightnesses of the k substrates, so as to obtain the diffraction fringe brightness corresponding to the lowest defect density according to the relationship matrix, and using the diffraction fringe brightness corresponding to the lowest defect density as the deoxidation completion point of the substrates to be deoxidized. The substrate deoxidation method provided by the present invention enables accurate determination of whether the substrate is just deoxidized completely.
[0076] An embodiment of the present invention provides a molecular beam epitaxy growth method for a semiconductor device, and the molecular beam epitaxy growth method for the semiconductor device includes:
[0077] First, obtain the deoxidation completion point of the substrate to be deoxidized by using the above-mentioned substrate deoxidation method.
[0078] For the above-mentioned substrate deoxidation method, refer to the above content and will not be elaborated here.
[0079] Then, deoxidize the substrate to be deoxidized, and detect the brightness of the diffraction fringes of the substrate to be deoxidized in real time during the deoxidation process, so as to stop the deoxidation when the brightness of the diffraction fringes of the substrate to be deoxidized reaches the deoxidation completion point.
[0080] By deoxidizing the substrate to be deoxidized to remove the oxide layer on the surface of the substrate to be deoxidized, the quality of the epitaxial layer formed on the substrate to be deoxidized by using the molecular beam epitaxy growth method subsequently can be improved.
[0081] When deoxidizing the substrate to be deoxidized, bake the substrate to be deoxidized at a high temperature to decompose the oxide layer, so as to remove the oxide layer on the surface of the substrate to be deoxidized. Among them, the temperature for baking the substrate to be deoxidized can be, for example, higher than 500 °C.
[0082] When deoxidizing a plurality of substrates to be deoxidized, the thicknesses of the oxide layers on the surfaces of the plurality of substrates to be deoxidized can be the same or different.
[0083] Then, form an epitaxial layer on the deoxidized substrate to be deoxidized by using a molecular beam epitaxy growth method.
[0084] Since the deoxidation completion point of the substrate to be deoxidized is obtained by using the substrate deoxidation method described above, and the deoxidation is stopped when the brightness of the diffraction fringes of the substrate to be deoxidized reaches the deoxidation completion point during the deoxidation of the substrate to be deoxidized, it is possible to accurately judge whether the substrate to be deoxidized is just deoxidized completely, avoiding incomplete deoxidation or over-deoxidation, improving the accuracy of judging whether the deoxidation is just completed, and also reducing the surface defect density after forming an epitaxial layer on the substrate to be deoxidized subsequently, improving the production quality of the epitaxial wafer; moreover, the thicknesses of the oxide layers on the substrates to be deoxidized provided by different manufacturers are different, and the thicknesses of the oxide layers on different batches of substrates to be deoxidized provided by the same manufacturer are also different. Therefore, when deoxidizing these substrates to be deoxidized, the deoxidation time required for just completing the deoxidation is not the same. However, in the present invention, it is only necessary to detect whether the brightness of the diffraction fringes of the substrate to be deoxidized reaches the brightness of the diffraction fringes corresponding to the lowest defect density to accurately judge whether the deoxidation is just completed, without considering the factors of deoxidation time and oxide layer thickness, and it has wide applicability; furthermore, since it is possible to accurately judge whether the deoxidation is just completed when deoxidizing the substrates to be deoxidized provided by different manufacturers and different batches, it is beneficial to ensure repeatability and improve the yield during the mass production of the epitaxial wafers.
[0085] The above description is only a description of the preferred embodiments of the present invention, and does not limit the scope of the present invention in any way. Any changes and modifications made by those of ordinary skill in the art of the present invention according to the above disclosure are within the protection scope of the claims.
Claims
1. A substrate deoxidation method, characterized in that, Including: Providing k substrates, an oxide layer is formed on the surface of the substrates, and the thicknesses of the oxide layers on the surfaces of the k substrates are different; Deoxidizing the substrates to remove the oxide layers on the surfaces of the substrates; And, during the deoxidization process, the brightness of the diffraction fringes of the substrates is detected in real time, so that the k substrates end the deoxidization with different diffraction fringe brightnesses; where k is an integer greater than or equal to 5; Using the molecular beam epitaxy growth method to form an epitaxial layer on the deoxidized substrates to form k epitaxial wafers; Performing a surface topography characterization test on the epitaxial wafers to obtain the defect densities on the surfaces of the k epitaxial wafers; Establishing a relationship matrix based on the defect densities of the k epitaxial wafers and the brightness of the diffraction fringes of the k substrates, so as to obtain the brightness of the diffraction fringes corresponding to the lowest defect density according to the relationship matrix, and using the brightness of the diffraction fringes corresponding to the lowest defect density as the deoxidization completion point of the substrate to be deoxidized.
2. The substrate deoxidation method according to claim 1, characterized in that The material of the substrate is InP, InAs or InSb.
3. The substrate deoxidation method according to claim 1, characterized in that, The defects on the surface of the epitaxial wafer include protrusions and depressions.
4. The substrate deoxidation method according to claim 1, wherein Before deoxidizing the substrates, the substrate deoxidization method further includes: Providing a substrate sample; Deoxidizing the substrate sample, and detecting the change in the brightness of the diffraction fringes of the substrate sample in real time during the deoxidization process; Taking the lowest value of the brightness of the diffraction fringes of the substrate sample as the reference brightness to calibrate the brightness of the diffraction fringes of the k substrates.
5. The substrate deoxidation method according to claim 4, characterized in that, The same preset As pressure and the same preset deoxidization temperature are used when deoxidizing the substrates and when deoxidizing the substrate sample.
6. The substrate deoxidation method according to claim 4, characterized in that The brightness of the diffraction fringes of the substrate refers to the brightness of the diffraction fringes in a specific area on the surface of the substrate, the brightness of the diffraction fringes of the substrate sample refers to the brightness of the diffraction fringes in a specific area on the surface of the substrate sample, and the position of the diffraction fringes in the specific area remains unchanged.
7. The substrate deoxidation method according to claim 4, characterized in that, The steps of detecting the brightness of the diffraction fringes of the substrate and the substrate sample include: Using a reflection high energy electron diffraction instrument to form the diffraction fringe pattern on the surfaces of the substrate and the substrate sample; Using an image analyzer to analyze the diffraction fringe pattern to obtain the brightness of the diffraction fringes.
8. A method for molecular beam epitaxial growth of a semiconductor device, characterized in that, Including: Obtaining the deoxidization completion point of the substrate to be deoxidized by using the substrate deoxidization method according to any one of claims 1 to 7; Deoxidizing the substrate to be deoxidized, and detecting the brightness of the diffraction fringes of the substrate to be deoxidized in real time during the deoxidization process, so as to stop deoxidizing when the brightness of the diffraction fringes of the substrate to be deoxidized reaches the deoxidization completion point; Using the molecular beam epitaxy growth method to form an epitaxial layer on the deoxidized substrate to be deoxidized.
9. The molecular beam epitaxy growth method of the semiconductor device according to claim 8, characterized in that, Deoxidizing multiple substrates to be deoxidized, and the thicknesses of the oxide layers on the surfaces of the multiple substrates to be deoxidized are the same or different.
Citation Information
Patent Citations
Molecular beam epitaxy process optimization method of InP-based semiconductor device
CN117116746A