Method for measuring bmds in heavily doped p-type silicon wafers, method and system for acquiring optimal heat treatment conditions for BMD growth in silicon wafers, and computer-readable medium

Abstract

A method for measuring BMDs in heavily doped P-type silicon wafers, a method and system for acquiring optimal heat treatment conditions for BMD growth in silicon wafers, and a computer-readable medium, relating to the field of semiconductors. The method for measuring BMDs in the heavily doped P-type silicon wafers comprises: providing a plurality of heavily doped P-type silicon wafers, and subjecting the silicon wafers to two-stage heat treatment under an oxygen-containing atmosphere, comprising: performing heat treatment at a first set temperature for a first set time, then heating to a second set temperature at a set heating rate, and performing heat treatment at the second set temperature for a second set time to grow BMDs in the silicon wafers; cleaning the silicon wafers in which the BMDs are grown; and measuring the silicon wafers to acquire the density and size of the BMDs of the silicon wafers. Relatively accurate quantification of the maximum BMD density that can be formed in silicon wafers is performed, so as to evaluate the characteristics of the heavily doped P-type silicon wafers, thereby providing guidance for subsequent processing steps.

Description

Measurement method for BMD of heavily doped p-type silicon wafers, method, system and computer-readable medium for obtaining optimal heat treatment conditions for BMD growth of silicon wafers. Technical Field

[0001] This invention relates to the field of semiconductor technology, and in particular to a method, system, computer-readable medium, and heavily doped P-type silicon wafer for obtaining optimal conditions for BMD thermal treatment during silicon wafer growth. Background Technology

[0002] Bulk micro-defect density (BMD) is an important physical parameter of silicon wafers. The density of BMD in a silicon wafer should not be too high or too low. A certain density of BMD can adsorb impurities from the silicon wafer surface into the wafer body, forming a denuded zone. However, excessively high BMD density can cause warping and deformation of the silicon wafer during processing, such as heat treatment. Excessive BMD can also cause leakage current in the pn junction of components, reducing minority carrier lifetime. Accurately quantifying the maximum BMD density that can be formed on a silicon wafer during silicon wafer production and device fabrication is crucial for evaluating the characteristics of heavily doped substrates and for guiding the development of appropriate subsequent processing techniques.

[0003] It should be noted that the information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for measuring the bulk density (BMD) of a heavily doped P-type silicon wafer, a method, system, and computer-readable medium for obtaining the optimal conditions for heat treatment of BMD growth on silicon wafers, in order to solve the problem of how to measure the density and size of BMD grown on a heavily doped P-type silicon wafer.

[0005] To solve the above technical problems, the present invention provides a method for measuring the BMD of heavily doped p-type silicon wafers, comprising:

[0006] A plurality of heavily doped P-type silicon wafers are provided, and the silicon wafers are subjected to two-stage heat treatment under oxygen conditions, including heat treatment at a first set temperature for a first set time, and then heating to a second set temperature at a set heating rate, and heat treatment at the second set temperature for a second set time, so as to grow BMD on the silicon wafers.

[0007] The silicon wafers with BMD grown are cleaned.

[0008] The silicon wafer is measured to obtain the density and size of the silicon wafer's BMD (Body Material Depth).

[0009] Optionally, the silicon wafer has an oxygen content ranging from 5 to 20 ppma and a resistivity of 0.01 to 0.02 ohm-cm.

[0010] Optionally, the silicon wafer has defect particles, and the number of defect particles with a diameter of 37 nm on the silicon wafer surface ranges from 0 to 7000.

[0011] Optionally, the first set temperature range is 600-900℃, the first set time range is 30min-300min, the second set temperature range is 900-1200℃, and the second set time range is 10h-20h.

[0012] Optionally, the first set temperature range is 630-760℃, the first set time range is 100min-200min, the second set temperature range is 950-1100℃, and the second set time range is 14h-18h.

[0013] Optionally, the cleaned silicon wafer is split into two halves along the crystal orientation, and the half-wafer is measured using a light scattering tomography microdefect analyzer to obtain the density and size of the silicon wafer's BMD.

[0014] Optionally, during the two-stage heat treatment, the oxygen flow rate is 5-10 L / min.

[0015] Optionally, after the silicon wafer undergoes two-stage heat treatment under oxygen conditions, an oxide film is formed on the surface of the silicon wafer. The cleaning process for the silicon wafer with grown BMD includes:

[0016] The silicon wafer is cleaned with a hydrofluoric acid solution with a concentration of 5-30% to remove the oxide film on the surface of the silicon wafer.

[0017] Based on the same inventive concept, this invention also provides a method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth, including:

[0018] Multiple heavily doped P-type silicon wafers were selected, and the silicon wafers were split into two sub-wafers, which were defined as control group silicon wafers and experimental group silicon wafers.

[0019] Multiple control group silicon wafers were subjected to a two-stage heat treatment, including heat treatment at 780°C for 3 hours under oxygen conditions, followed by heating to 1000°C at a set heating rate and heat treatment at 1000°C for 16 hours, and the BMD density and BMD size of each control group silicon wafer were obtained.

[0020] The experimental group silicon wafers were measured using the measurement method described above to obtain the BMD density and BMD size of each experimental group silicon wafer.

[0021] By comparing the BMD density and BMD size of control group silicon wafers and experimental group silicon wafers split from multiple silicon wafers of the same wafer, the target data that shows the largest relative difference in BMD size and the largest relative difference in BMD density is obtained. The heat treatment conditions of the experimental group silicon wafer corresponding to this target data are the optimal BMD heat treatment conditions.

[0022] Optionally, comparing the BMD density and BMD size of control group silicon wafers and experimental group silicon wafers split from multiple silicon wafers of the same wafer includes:

[0023] The coordinates of the control group silicon wafers and the experimental group silicon wafers were obtained through a detection system.

[0024] The BMD density and BMD size of control group silicon wafers and experimental group silicon wafers with the same coordinates were compared.

[0025] Based on the same inventive concept, this invention also provides a system for obtaining optimal conditions for BMD thermal treatment of silicon wafer growth, comprising:

[0026] The acquisition module is used to acquire the BMD density and BMD size of each control group silicon wafer; and to acquire the BMD density and BMD size of each experimental group silicon wafer.

[0027] The comparison module is used to compare the BMD density and BMD size of control group silicon wafers and experimental group silicon wafers split from multiple silicon wafers of the same wafer, and to obtain the target data where the relative difference in BMD size remains unchanged and the relative difference in BMD density is the largest. The heat treatment conditions of the experimental group silicon wafer corresponding to the target data are the optimal BMD heat treatment conditions.

[0028] Based on the same inventive concept, the present invention also provides a computer-readable medium having a program stored thereon, comprising:

[0029] When the program is executed, at least some of the steps in the method for obtaining optimal conditions for BMD heat treatment as described above are performed.

[0030] Compared with the prior art, the method for measuring the BMD of heavily doped p-type silicon wafers of the present invention has the following advantages:

[0031] This invention provides several heavily doped P-type silicon wafers and subjects them to a two-stage heat treatment under oxygen-containing conditions. The heat treatment includes a first predetermined time at a first predetermined temperature, followed by heating to a second predetermined temperature at a predetermined heating rate, and then further heating for a second predetermined time at the second predetermined temperature to grow bone-like growth media (BMDs). The BMD-grown silicon wafers are then cleaned. Measurements are performed on the silicon wafers to obtain the density and size of the BMDs. By measuring the density and size of the BMDs grown on the heavily doped P-type silicon wafers, a relatively accurate quantification of the maximum BMD density formed on the heavily doped P-type silicon wafers can be achieved. This allows for the evaluation of the characteristics of heavily doped P-type silicon wafers as heavily doped substrates and provides guidance for subsequent processing.

[0032] The method, system, and computer-readable medium for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth provided by this invention belong to the same inventive concept as the method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth provided by this invention. Therefore, the system, computer-readable medium, and heavily doped P-type silicon wafer for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth provided by this invention have at least all the advantages of the method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth provided by this invention. It can perform a relatively accurate quantification of the maximum BMD density formed to evaluate the characteristics of the heavily doped P-type silicon wafer, which has guiding significance for subsequent processing technology. Attached Figure Description

[0033] Figure 1 is a comparison of BMD densities obtained after heat treatment of a lightly doped P-type silicon wafer at 780°C and under different temperature conditions.

[0034] Figure 2 is a flowchart of a method for measuring the BMD of a heavily doped P-type silicon wafer according to an embodiment of the present invention.

[0035] Figure 3 is a schematic diagram of a silicon wafer split into two pieces according to an embodiment of the present invention;

[0036] Figure 4 is a flowchart of a method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth in one embodiment of the present invention;

[0037] Figure 5 is a schematic diagram of the nucleation heat treatment temperature curve of a heavily doped P-type silicon wafer at 780°C in one embodiment of the present invention.

[0038] Figure 6 is a schematic diagram of the nucleation heat treatment temperature curves of a heavily doped P-type silicon wafer with BMD at different temperatures in one embodiment of the present invention.

[0039] Figure 7 is a comparison of BMD densities obtained by heat treatment of heavily doped P-type silicon wafers at 780°C and under different temperature conditions in one embodiment of the present invention.

[0040] Figure 8 is a comparison of the BMD size obtained by heat treatment of heavily doped P-type silicon wafers at 780°C and under different temperature conditions in one embodiment of the present invention.

[0041] Figure 9 is a schematic diagram showing the relative difference in BMD density between the control group silicon wafer and the experimental group silicon wafer in one embodiment of the present invention as a function of temperature.

[0042] Figure 10 is a schematic diagram showing the relative difference in BMD size between the control group silicon wafer and the experimental group silicon wafer in one embodiment of the present invention as a function of temperature.

[0043] Figure 11 is a schematic diagram comparing the BMD density and BMD size of three heavily doped P-type silicon wafers obtained at a nucleation temperature of 650℃-730℃ in one embodiment of the present invention with the measurement results of BMD density and BMD size obtained by heat treatment as described in the SEMI M90-0821 standard document.

[0044] In the figure, 100 - control group silicon wafer; 200 - experimental group silicon wafer; 300 - notch. Detailed Implementation

[0045] To make the objectives, advantages, and features of the present invention clearer, the method for obtaining optimal BMD heat treatment conditions for silicon wafer growth proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and use non-precise scales, only for the purpose of conveniently and clearly illustrating the embodiments of the present invention. It should be understood that the drawings do not necessarily show the specific structure of the present invention to scale, and the illustrative features used to illustrate certain principles of the present invention in the drawings are also drawn in a slightly simplified manner. Specific design features of the present invention disclosed herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the specific application and environment in which they are used. Furthermore, in the embodiments described below, the same reference numerals are sometimes used across different drawings to denote the same parts or parts having the same function, and their repeated descriptions are omitted. In this specification, the same reference numerals and letters are used to denote the same items; therefore, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0048] Before measuring the bulk density (BMD) of silicon wafers, an oxidation annealing process is required for detection. The SEMI M90-0821 standard document describes a BMD oxidation nucleation process involving heat treatment at 780°C for 3 hours to obtain clean areas on the annealed wafer. This method is suitable for wafers with a resistivity greater than 0.01 Ω·cm. However, this method is limited to annealed wafers and not applicable to epitaxial wafers. Furthermore, the BMD detection method, which involves mixed acid etching followed by microscopic imaging, has significantly lower accuracy than the light scattering tomography (LSTD) method. The SEMI MF1239-0305 standard document describes a two-step heat treatment process: heat treatment at 750°C for 4 hours and at 1050°C for 16 hours. Oxygen deposition is characterized by the difference in interstitial oxygen content using spectroscopy. However, this method is suitable for P- or N-type wafers, but not for P+ type wafers. Additionally, this method does not directly measure BMD data. The industry refers to the two SEMI standards mentioned above for BMD heat treatment methods.

[0049] Patent publication number KR20040050780A discloses a method for forming BMD nuclei on a silicon wafer. The method to improve BMD uniformity involves setting the nucleation temperature of the heat treatment to 600-750℃. However, whether nucleation at this temperature affects the average density of BMD on the silicon wafer remains unknown, and whether the BMD density obtained at this nucleation temperature can represent the true value of BMD is also unknown. According to our previous experimental data, the average BMD density of lightly doped substrates did not change when nucleating at 580-830℃. Whether this phenomenon applies to heavily doped substrates is also unknown. Since heavily doped substrates have a higher doping level than lightly doped substrates, their bulk microdefect density is much higher. Whether the BMD level formed under different temperature conditions is consistent requires further investigation. Therefore, a relatively accurate quantification of the maximum BMD density that can be formed on a silicon wafer is needed to evaluate the characteristics of heavily doped substrates, which has guiding significance for subsequent IC processing.

[0050] As shown in Figure 1, our previous experimental data indicate that the BMD nucleation temperature has a relatively small impact on the BMD density of lightly doped P-type silicon wafers (i.e., the P-substrate in Figure 1). Compared with the heat treatment described in the SEMI M90-0821 standard document, the BMD density values ​​fall within the 1:1 range, and the average BMD density of P-substrates obtained at different temperatures, such as 630-830℃, remains unchanged. For heavily doped P-type silicon wafers (i.e., P+ substrates), whether the BMD density changes at different BMD nucleation temperatures is unknown. Therefore, for heavily doped P-type silicon wafers, a relatively accurate quantification of the maximum achievable BMD density is needed to evaluate the characteristics of heavily doped substrates and provide guidance for developing appropriate subsequent processing techniques.

[0051] The core idea of ​​this invention is to provide a method for measuring the BMD of heavily doped P-type silicon wafers, obtaining the density and size of the BMD grown on the heavily doped P-type silicon wafers, thereby enabling a relatively accurate quantification of the maximum BMD density formed on the heavily doped P-type silicon wafers, in order to evaluate the characteristics of the heavily doped P-type silicon wafers as heavily doped substrates, and providing guidance for subsequent processing.

[0052] To achieve the above-mentioned goals, this invention provides a method for measuring the basis metallization (BMD) of a heavily doped P-type silicon wafer, as illustrated in Figures 2 and 3. This method includes the following steps S11 to S14.

[0053] Step S11: Provide a plurality of heavily doped P-type silicon wafers, and perform two-stage heat treatment on the silicon wafers under oxygen-containing conditions, including heat treatment at a first set temperature for a first set time, and then heating to a second set temperature at a set heating rate, and heat treatment at the second set temperature for a second set time to form BMD on the silicon wafers.

[0054] Specifically, as shown in Figure 2, the heavily doped P-type silicon wafer is a monocrystalline silicon wafer. The oxygen content of the silicon wafer ranges from 5-20 ppma (New ASTM ppma), and the resistivity is 0.01-0.02 ohm-cm. In this embodiment, the P-type silicon wafer is formed by doping with P-type impurities such as boron (B) and gallium (GA), and the resistivity characterizes the concentration of silicon doping, ranging from 0.01-0.02 ohm-cm. The silicon wafer has defect particles. Since the more defect particles there are, the more BMDs are formed, in this embodiment, the number of defect particles with a diameter of 37 nm on the silicon wafer surface ranges from 0-7000.

[0055] The step of performing a two-stage heat treatment on the silicon wafer under oxygen-containing conditions to form BMD on the silicon wafer includes:

[0056] First, under aerobic conditions, the silicon wafer is heat-treated at a first set temperature for a first set time. The silicon wafer is placed in a furnace tube at an oxygen flow rate of 5-10 L / min. The temperature of the furnace tube is adjusted to the first set temperature, and the heat treatment is continued for the first set time. The first set temperature range is 600-900℃. The first set time range is 30 min-300 min. That is, the first set temperature range can be 600℃, 630℃, 700℃, 760℃, 780℃, 770℃, 785℃, 800℃, 900℃, or any temperature value within the range of 600-900℃. The first set time can be 30 min, 180 min, 100 min, 200 min, 300 min, or any time within the range of 30 min-300 min. In this embodiment, optionally, the first set temperature range is 630-760℃, and the first set time is 100 min-200 min.

[0057] Then, under oxygen-containing conditions, the silicon wafer is heated at a second set temperature for a second set time to form BMD on the silicon wafer. Oxygen is continuously introduced into the furnace tube at a rate of 5-10 L / min. The furnace tube is heated to the second set temperature at a rate of 10°C / min, and heat-treated at this temperature for a second set time to allow BMD growth. The range of the second set temperature is 900-1200°C. The range of the second set time is 10h-20h. That is, the second set temperature range can be 900°C, 9500°C, 1000°C, 1100°C, 1200°C, or any temperature value within the range of 900-1200°C. The second set time can be 10h, 14h, 18h, 20h, or any time within the range of 10h-20h. In this embodiment, optionally, the second set temperature range is 950-1100°C, and the second set time range is 14h-18h.

[0058] After the two-stage heat treatment described above, BMD grows inside the silicon wafer.

[0059] Step S12: Clean the silicon wafer with BMD grown on it.

[0060] Specifically, as shown in Figure 2, after two stages of heat treatment, an oxide film forms on the surface of the silicon wafer. Since the oxide film affects subsequent BMD measurements, it needs to be removed. The silicon wafer is cleaned with a 10% hydrofluoric acid solution to remove the oxide film. Of course, other cleaning solutions can also be used to remove the oxide layer. For example, a mixture of hydrochloric acid and hydrogen peroxide can be used. The choice of cleaning solution is not specific, as long as the oxide layer can be removed. Optionally, a 10% hydrofluoric acid solution is used to clean the silicon wafer to remove the oxide film and avoid affecting the BMD measurement results.

[0061] Step S13: Split the cleaned silicon wafer into two halves along the silicon wafer crystal orientation.

[0062] Specifically, as shown in Figures 2 and 3, the cleaned silicon wafer is split into two halves along its crystal orientation. After selecting the desired monocrystalline silicon wafer, each wafer is split into two pieces along its crystal orientation. During the silicon wafer straightening process, one side of the wafer has a notch 300 that characterizes the crystal orientation of the wafer. <100> Taking a silicon wafer with a specific crystal orientation as an example, its crystal orientation is 45° away from the notch 300. For silicon wafers with other crystal orientations, the specific operation of splitting them into two pieces along their crystal orientation is already familiar to those skilled in the art, and will not be described in detail here.

[0063] Step S14: Measure the half silicon wafer to obtain the density and size of the silicon wafer BMD.

[0064] Specifically, as shown in Figures 2 and 3, a half-wafer of silicon is loaded into an LSTD (Laser-Solved Surface Test) machine for testing. During testing, multiple test points are located radially near the split surface of the half-wafer. Adjacent test points may be equal or unequal. Optionally, multiple test points at regions a and b in Figure 3 can be selected at this radial location; for example, 19 test points can be selected to measure the half-wafer and obtain the BMD density and BMD size of each half-wafer. Each test point has corresponding coordinates within the silicon wafer. The BMD density is the number of BMDs generated per unit cubic centimeter, expressed in units of ea / cm². 3 The BMD has a spherical structure. The size of the BMD is its diameter.

[0065] The density and size of the BMD grown on the heavily doped P-type silicon wafer are measured using the above measurement method. This allows for a relatively accurate quantification of the maximum BMD density formed on the heavily doped P-type silicon wafer, which is of guiding significance for evaluating the characteristics of the heavily doped P-type silicon wafer as a heavily doped substrate and for subsequent processing technology.

[0066] To achieve the above-mentioned goals, this invention provides a method for obtaining optimal BMD heat treatment conditions for silicon wafer growth, as illustrated in Figures 3 to 11. This method includes the following steps S21 to S26.

[0067] Step S21: Select multiple heavily doped P-type silicon wafers, split the silicon wafers into two sub-wafers, and define the two sub-wafers as control group silicon wafer 100 and experimental group silicon wafer 200.

[0068] Specifically, referring to Figures 3 and 4, several heavily doped P-type silicon wafers (hereinafter referred to as "wafers") were selected. The silicon wafers are P-type substrates doped with elements such as boron and aluminum. The P-type substrates are heavily doped. The oxygen content of the silicon wafers ranges from 5 ppma to 20 ppma. The resistivity is 0.01 ohm-cm to 0.02 ohm-cm. The resistivity characterizes the amount of doping on the silicon wafer substrate. The silicon wafers contain defect particles, and the number of defect particles with a diameter of 37 nm on the silicon wafer surface ranges from 0 to 7000.

[0069] After selecting the desired silicon wafers, each wafer is split into two sub-wafers along its crystal orientation. During the wafer straightening process, one side of the wafer has a notch 300 that characterizes its crystal orientation. <100> Taking a silicon wafer with a specific crystal orientation as an example, its crystal orientation is 45° away from the notch 300. For silicon wafers with other crystal orientations, the specific operation of splitting them into two sub-wafers along their crystal orientation is already familiar to those skilled in the art and will not be described further here. The two sub-wafers split from the same silicon wafer are defined as control group silicon wafer 100 and experimental group silicon wafer 200, respectively.

[0070] Step S22: Perform a two-stage heat treatment on multiple control group silicon wafers, including heat treatment at 780°C for 3 hours under oxygen conditions, and then heat treatment at 1000°C for 16 hours at a set heating rate.

[0071] Specifically, as shown in Figure 5, before conveying multiple control group silicon wafers 100 to the furnace tube, oxygen needs to be introduced into the furnace tube at a rate of 5-10 L / min. Next, the multiple control group silicon wafers 100 are conveyed into the furnace tube and heat-treated according to the heat treatment method described in the SEMI M90-0821 standard document. This heat treatment process includes two stages. The first stage involves heating the furnace tube to 780°C and heat-treating at this temperature for 3 hours to allow BMD nucleation to begin. The second stage involves heating the furnace tube to 1000°C at a rate of 10°C / min and heat-treating at this temperature for 16 hours to allow BMD growth. Alternatively, the furnace tube can be heated to 1000°C at rates of 20°C / min or 30°C / min; no specific limitation is made here. In this embodiment, optionally, the furnace tube is heated at a rate of 10°C / min.

[0072] Step S23: Clean the multiple control group silicon wafers 100 after the two-stage heat treatment, and measure them after cleaning to obtain the BMD density and BMD size of each control group silicon wafer 100.

[0073] Specifically, refer to Figures 3 to 5. After the two-stage heat treatment, the oxide layer on the surface of multiple control group silicon wafers 100 is cleaned. For example, a 5-30% hydrofluoric acid solution can be used to clean the silicon wafers to remove the oxide film on the silicon wafer surface. Of course, other cleaning solutions can also be used to remove the oxide layer on the silicon wafer surface. For example, a mixture of hydrochloric acid and hydrogen peroxide can be used to remove the oxide layer. As long as the oxide layer can be removed, there are no specific requirements for the choice of cleaning solution. Optionally, a 10% hydrofluoric acid solution can be used to clean the silicon wafers to remove the oxide film on the silicon wafer surface. Next, the control group silicon wafers 100 are loaded into an LSTD machine for testing. During testing, there are multiple test points on the radial position of the control group silicon wafers 100 near the split surface. Two adjacent test points may be equal or unequal. Optionally, multiple test points can be selected at this radial location, in region a of Figure 3. For example, 19 test points can be selected to measure the BMD density and BMD size of the control group silicon wafer 100. Each test point has corresponding coordinates in the silicon wafer. The BMD density is the number of BMDs generated per unit cubic centimeter, expressed in units of ea / cm². 3 The BMD is a spherical structure. The BMD size is the diameter of the BMD. The BMD density and BMD size of each control group silicon wafer 100 are denoted as BMD. 密度 对照组 and BMD 大小对照组 .

[0074] Step S24: Divide the multiple experimental silicon wafers 200 into n groups, and subject each group of experimental silicon wafers 200 to a two-stage heat treatment, including treatment under oxygen-containing conditions, with each group subjected to a set temperature t. n Under the given conditions, heat treatment is performed for a first set time, followed by heating to a second set temperature at a set heating rate. At the second set temperature, heat treatment is performed for a second set time, where n is an integer greater than 1, and t is the temperature for each group. n The temperature conditions are all different, and t n The value range is 630℃≤t n ≤830℃.

[0075] Specifically, refer to Figures 3 to 6. Multiple experimental silicon wafers 200 were divided into several groups, and each group of experimental silicon wafers 200 underwent a two-stage heat treatment. Before conveying the multiple experimental silicon wafers 200 to the furnace tube, oxygen was introduced into the furnace tube at a rate of 5-10 L / min. Then, the multiple experimental silicon wafers 200 were conveyed to the furnace tube for heat treatment. This heat treatment consisted of two stages. The first stage involved heating the furnace tube of the first group of experimental silicon wafers 200 to t1 and heat-treating at t1 for 3 hours to initiate BMD nucleation. The second stage involved heating the furnace tube to 1000℃ at a rate of 10℃ / min and heat-treating at this temperature for 16 hours to allow BMD growth. Where 630℃ ≤ t1 ≤ 830℃.

[0076] Next, the furnace tubes of multiple experimental silicon wafers in the second group were heated to t2 and heat-treated at t2 for 3 hours to induce BMD nucleation. Then, the furnace tubes were heated to 1000℃ at a rate of 10℃ / min and heat-treated at this temperature for 16 hours to allow BMD growth. Furthermore, t1 ≠ t2, and 630℃ ≤ t2 ≤ 830℃.

[0077] Similarly, during the first stage heat treatment of the nth (where n is an integer greater than 1) group of experimental silicon wafers 200, the furnace tubes of the nth group of experimental silicon wafers 200 are heated to t. n and in t n Under the specified temperature conditions, heat treatment was performed for 3 hours to induce BMD nucleation. Then, the furnace tube was heated to 1000℃ at a rate of 10℃ / min, and heat-treated at this temperature for 16 hours to allow BMD growth. Where 630℃ ≤ t n ≤830℃.

[0078] As an optional embodiment, multiple experimental silicon wafers 200 are divided into 6 groups. The set temperature t1 of the first group is 830℃. The set temperature t2 of the second group is 790℃. The set temperature t3 of the third group is 760℃. The set temperature t4 of the fourth group is 730℃. The set temperature t5 of the fifth group is 680℃. The set temperature t6 of the sixth group is 630℃. The following explanation uses the multiple experimental silicon wafers 200 divided into 6 groups. Referring to Figure 6, the curves at point c in Figure 6 are formed after heat treatment for 3 hours at temperatures of 830℃, 790℃, 760℃, 730℃, 680℃, and 630℃ respectively. At this curve, BMD nucleation begins.

[0079] Step S25: Clean the multiple experimental silicon wafers 200 after the two-stage heat treatment, and measure them after cleaning to obtain the BMD density and BMD size of each experimental silicon wafer 200.

[0080] Specifically, refer to Figures 3 to 8. After the oxide layer on the surface of the experimental silicon wafer 200 was removed by cleaning, BMD measurements were performed on the test points at the same coordinates as those in step S2 using a light scattering tomography microdefect analyzer on each experimental silicon wafer 200. The experimental silicon wafer 200 also has test points at region b in Figure 3, corresponding to the coordinates of the control group silicon wafer 100. To maintain consistency with the coordinates of the test points on the control group silicon wafer 100, 19 test points were selected for the experimental silicon wafer 200, and each test point corresponds to a test point on the control group silicon wafer 100. The coordinates of the 19 test points on the experimental silicon wafer 200 are the same as those on the control group silicon wafer 100. The BMD density and BMD size of the test points at the same coordinates on the control group silicon wafer 100 and the experimental silicon wafer 200 were obtained and denoted as BMD. 密度实验组 and BMD 大小实验组 .

[0081] As shown in Figure 7, the nucleation temperature has a significant impact on the BMD density of heavily doped P-type silicon wafers (i.e., the P+ substrate in Figure 7). Compared with the heat treatment process described in the SEMI M90-0821 standard document, the BMD density of the P+ substrate increases significantly in the temperature range of 630-760℃, reaching its maximum value at 680℃. In the temperature range of 780-830℃, the BMD density of the P+ substrate decreases with increasing temperature. However, as shown in Figure 8, the size of the P+ substrate BMD does not show a significant change within the temperature range of 630℃-830℃.

[0082] Step S26: Compare the BMD density and BMD size of multiple control group silicon wafers 100 and experimental group silicon wafers 200 split from the same silicon wafer, and obtain the target data where the relative difference in BMD size remains unchanged and the relative difference in BMD density is the largest. Then, the heat treatment conditions of the experimental group silicon wafer 200 corresponding to the target data are the optimal BMD heat treatment conditions.

[0083] Specifically, referring to Figures 3, 4, and 9 to 11, the coordinates of the control group silicon wafer 100 and the experimental group silicon wafer 200 are obtained through the detection system. The BMD density and BMD size of the control group silicon wafer 100 and the experimental group silicon wafer 200 with the same coordinates are compared. The BMD density and BMD size data of the control group silicon wafer 100 and the experimental group silicon wafer 200 split from the same silicon wafer are compared. The target data where the relative difference in BMD size remains constant and the relative difference in BMD density is the largest is obtained. Therefore, the heat treatment conditions of the experimental group silicon wafer 200 corresponding to this target data are the optimal BMD heat treatment conditions. Wherein, the relative difference in BMD density (%) = (BMD... 密度实验组 -BMD 密度对照组 ) / BMD 密度对照组 ×100. Relative difference in BMD size (%) = (BMD) 大小实验组 -BMD 大小对照组 ) / BMD 大小对照组 ×100.

[0084] As shown in Figure 9, the relative difference in BMD density of P+ substrates increases significantly within the nucleation temperature range of 630-760℃, while in the temperature range of 760-830℃, the relative difference in BMD density of P+ substrates decreases with increasing temperature. As shown in Figure 10, the relative difference in BMD size of P+ substrates does not show significant change within the temperature range of 630℃-830℃.

[0085] Referring to Figure 11, it can be seen that for wafer 1 (i.e., Wafer 1 in Figure 11), wafer 2 (i.e., Wafer 2 in Figure 11), and wafer 3 (i.e., Wafer 3 in Figure 11), Figure (11a) is a schematic diagram of the measurement results of BMD density and BMD size of three heavily doped P-type silicon wafers obtained according to the heat treatment described in the SEMI M90-0821 standard document. Figure (11b) is a schematic diagram of the measurement results of BMD density and BMD size of three heavily doped P-type silicon wafers obtained at a nucleation temperature of 650℃-730℃. The comparison results of BMD density and BMD size of three different P+ substrates at a nucleation temperature of 650℃-730℃ with the BMD density and BMD size obtained according to the heat treatment described in the SEMI M90-0821 standard document show that: BMD density increases significantly, while BMD size does not change significantly.

[0086] As can be seen from the above description, optionally, the optimal nucleation temperature on a P+ substrate is 630℃-760℃. Optionally, the optimal nucleation temperature on a P+ substrate is 650-730℃.

[0087] The method for obtaining the optimal heat treatment conditions for BMD growth on silicon wafers, as disclosed in this embodiment, not only reveals that the BMD density changes at different BMD nucleation temperatures for heavily doped P-type silicon wafers, but also enables a relatively accurate quantification of the maximum BMD density formed, obtaining the optimal heat treatment conditions for BMD density. This allows for the evaluation of the characteristics of heavily doped substrates and provides guidance for developing corresponding downstream processing techniques.

[0088] To achieve the above-mentioned idea, this embodiment also discloses a system for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth, including:

[0089] The acquisition module is used to acquire the BMD density and BMD size of each control group silicon wafer 100; and to acquire the BMD density and BMD size of each experimental group silicon wafer 200.

[0090] The comparison module is used to compare the BMD density and BMD size of multiple control group silicon wafers 100 and experimental group silicon wafers 200 split from the same silicon wafer, and to obtain the target data where the relative difference in BMD size remains unchanged and the relative difference in BMD density is the largest. The heat treatment conditions of the experimental group silicon wafer 200 corresponding to the target data are the optimal BMD heat treatment conditions.

[0091] To achieve the above idea, this embodiment also discloses a computer-readable medium having a program stored thereon, including:

[0092] When the program is executed, at least some of the steps in the method for obtaining optimal conditions for BMD heat treatment as described above are performed.

[0093] To achieve the above idea, this embodiment also discloses a heavily doped P-type silicon wafer, comprising:

[0094] The silicon wafer is heat-treated using the heat treatment conditions obtained by the method for obtaining the optimal conditions for BMD heat treatment as described above, so as to grow BMD on the silicon wafer.

[0095] The system, computer-readable medium, and heavily doped P-type silicon wafer provided in this embodiment for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth all belong to the same inventive concept as the method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth provided in this embodiment. Therefore, the system, computer-readable medium, and heavily doped P-type silicon wafer provided in this embodiment for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth have at least all the advantages of the method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth provided in this embodiment. They can perform a relatively accurate quantification of the maximum BMD density formed to evaluate the characteristics of the heavily doped P-type silicon wafer, which has guiding significance for subsequent processing technology.

[0096] In summary, the above embodiments have provided detailed descriptions of different configurations of the method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth. Of course, the above descriptions are only descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention in any way. The present invention includes but is not limited to the configurations listed in the above embodiments. Those skilled in the art can draw inferences from the above embodiments. Any changes or modifications made by those skilled in the art based on the above disclosure are within the protection scope of the claims.

Claims

1. A method for measuring the bone matrix mating depth (BMD) of a heavily doped p-type silicon wafer, characterized in that, include: A plurality of heavily doped P-type silicon wafers are provided, and the silicon wafers are subjected to two-stage heat treatment under oxygen conditions, including heat treatment at a first set temperature for a first set time, and then heating to a second set temperature at a set heating rate, and heat treatment at the second set temperature for a second set time, so as to grow BMD on the silicon wafers. The silicon wafers with BMD grown are cleaned. The silicon wafer is measured to obtain the density and size of the silicon wafer's BMD (Body Material Depth).

2. The method for measuring the BMD of heavily doped p-type silicon wafers according to claim 1, characterized in that, The silicon wafer has an oxygen content ranging from 5 to 20 ppma and a resistivity of 0.01 to 0.02 ohm-cm.

3. The method for measuring the BMD of heavily doped p-type silicon wafers according to claim 1, characterized in that, The silicon wafer has defective particles, and the number of defective particles with a diameter of 37 nm on the surface of the silicon wafer ranges from 0 to 7000.

4. The method for measuring the BMD of heavily doped p-type silicon wafers according to claim 1, characterized in that, The first set temperature range is 600-900℃, the first set time range is 30min-300min, the second set temperature range is 900-1200℃, and the second set time range is 10h-20h.

5. The method for measuring the BMD of heavily doped p-type silicon wafers according to claim 4, characterized in that, The first set temperature range is 630-760℃, the first set time range is 100min-200min, the second set temperature range is 950-1100℃, and the second set time range is 14h-18h.

6. The method for measuring the BMD of heavily doped p-type silicon wafers according to claim 1, characterized in that, After cleaning, the silicon wafer is split into two halves along the crystal orientation. The half-wafer is then measured using a light scattering tomography microdefect analyzer to obtain the density and size of the silicon wafer's bulk density (BMD).

7. The method for measuring the BMD of heavily doped p-type silicon wafers according to claim 1, characterized in that, During the two-stage heat treatment, the oxygen flow rate is 5-10 L / min.

8. The method for measuring the BMD of heavily doped p-type silicon wafers according to claim 1, characterized in that, After the silicon wafer undergoes two-stage heat treatment under oxygen conditions, an oxide film is formed on the surface of the silicon wafer. The cleaning process for the silicon wafer with grown BMD includes: The silicon wafer is cleaned with a hydrofluoric acid solution with a concentration of 5-30% to remove the oxide film on the surface of the silicon wafer.

9. A method for obtaining optimal heat treatment conditions for BMD (Bipolar Modulation) in silicon wafer growth, characterized in that, include: Multiple heavily doped P-type silicon wafers were selected, and the silicon wafers were split into two sub-wafers, which were defined as control group silicon wafers and experimental group silicon wafers. Multiple control group silicon wafers were subjected to a two-stage heat treatment, including heat treatment at 780°C for 3 hours under oxygen conditions, followed by heating to 1000°C at a set heating rate and heat treatment at 1000°C for 16 hours, and the BMD density and BMD size of each control group silicon wafer were obtained. The experimental group silicon wafers were measured using the measurement method described in any one of claims 1-8 to obtain the BMD density and BMD size of each experimental group silicon wafer; By comparing the BMD density and BMD size of control group silicon wafers and experimental group silicon wafers split from multiple silicon wafers of the same wafer, the target data that shows the largest relative difference in BMD size and the largest relative difference in BMD density is obtained. The heat treatment conditions of the experimental group silicon wafer corresponding to this target data are the optimal BMD heat treatment conditions.

10. The method for obtaining the optimal conditions for BMD thermal treatment of silicon wafer growth according to claim 9, characterized in that, The comparison of BMD density and BMD size between control group silicon wafers and experimental group silicon wafers split from multiple identical silicon wafers includes: The coordinates of the control group silicon wafers and the experimental group silicon wafers were obtained through a detection system. The BMD density and BMD size of control group silicon wafers and experimental group silicon wafers with the same coordinates were compared.

11. A system for obtaining optimal conditions for BMD thermal treatment of silicon wafer growth, comprising: The acquisition module is used to acquire the BMD density and BMD size of each control group silicon wafer; and to acquire the BMD density and BMD size of each experimental group silicon wafer. The comparison module is used to compare the BMD density and BMD size of control group silicon wafers and experimental group silicon wafers split from multiple silicon wafers of the same wafer, and to obtain the target data where the relative difference in BMD size remains unchanged and the relative difference in BMD density is the largest. The heat treatment conditions of the experimental group silicon wafer corresponding to the target data are the optimal BMD heat treatment conditions.

12. A computer-readable medium having a program stored thereon, characterized in that, include: When the program is executed, at least some steps of the method for obtaining optimal conditions for BMD heat treatment as described in claim 9 or 10 are performed.

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