Silicon wafer metal pollution detection method
By constructing Formula 1 and 2, combined with a total reflective X-ray fluorescence spectrometer, the content of metal elements at any position on the surface of the silicon wafer is quickly determined, which solves the problems of frequent detection times and long time in the existing technology, and achieves efficient detection of metal pollution of silicon wafers.
Patent Information
- Application Number
- CN202311847942.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-28
- Publication Date
- 2025-07-01
AI Technical Summary
The existing silicon wafer metal pollution detection methods are difficult to detect the content of metal elements at different locations on the silicon wafer surface in a timely and effective manner, resulting in a large number of detections and a long time, and the inability to obtain accurate metal elements distribution in a timely manner.
By constructing Formula 1 and 2, the metal element content in the contamination center of the silicon wafer to be tested, combined with a total reflective X-ray fluorescence spectrometer, the metal element content at any position on the surface of the silicon wafer is quickly determined, reducing the number of detections, and improving detection efficiency.
It realizes the rapid and accurate determination of the metal element content at any position on the surface of the silicon wafer, which reduces the number of detections, shortens the detection time, and improves the detection efficiency and detection level.
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Figure CN120237028A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of integrated circuits, and particularly to a method for detecting metal contamination on a silicon wafer. Background Art
[0002] With the development of large-scale integrated circuits, the chip integration degree has been continuously improved, the line width has been continuously reduced, and the quality requirements for silicon wafers have also become higher and higher. Various metal impurities will be introduced during the silicon wafer processing, and the metal impurity contamination on the silicon wafer surface will seriously affect the quality and yield of semiconductor devices. Therefore, it is necessary to detect the metal contamination on the silicon wafer.
[0003] However, the existing methods for detecting metal contamination on silicon wafers are difficult to detect the metal element contents at different positions on the silicon wafer surface in a timely and effective manner. Summary of the Invention
[0004] Based on this, it is necessary to provide a method for detecting metal contamination on a silicon wafer to solve the problem that the existing methods for detecting metal contamination on silicon wafers are difficult to detect the metal element contents at different positions on the silicon wafer surface in a timely and effective manner.
[0005] To achieve the above object, in a first aspect, the present invention provides a method for detecting metal contamination on a silicon wafer, including: providing a silicon wafer to be tested, the silicon wafer to be tested having a first surface and a second surface which are oppositely arranged, and the first surface having a contamination center; constructing Formula 1, which is used to reflect the relationship between the metal element contents at any position on the first surface of the silicon wafer to be tested and the contamination center of the silicon wafer to be tested; determining the position of the contamination center of the silicon wafer to be tested and the metal element content of the current contamination center of the silicon wafer to be tested, and combining Formula 1 to obtain the metal element content at any position on the first surface of the current silicon wafer to be tested.
[0006] The above method for detecting metal contamination on a silicon wafer only needs to determine the metal element content of the contamination center of the silicon wafer to be tested to obtain the metal element content at any position on the surface of the current silicon wafer to be tested in a timely and effective manner, without the need to detect each position, which reduces the number of detections, shortens the detection time, and improves the detection efficiency.
[0007] In some embodiments, the steps of constructing Formula 1 include: providing a preliminary silicon wafer that is free of metal contamination and has the same doping type as the silicon wafer to be measured; removing the oxide film on the surface of the preliminary silicon wafer; dropping a metal standard solution on the surface of the preliminary silicon wafer and drying it to contaminate the preliminary silicon wafer with metal. The position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer; performing physical treatment on the preliminary silicon wafer to diffuse the metal elements in the preliminary silicon wafer; detecting the metal element contents at multiple points at the contamination center and its side of the preliminary silicon wafer, and measuring the distance from each point to the contamination center of the preliminary silicon wafer to obtain a number of first data sets; fitting the data of the number of first data sets to obtain Formula 1.
[0008] In some embodiments, the steps of determining the position of the contamination center of the silicon wafer to be measured and the metal element content of the current contamination center of the silicon wafer to be measured include: detecting the metal element contents at at least three points on the first surface of the current silicon wafer to be measured; substituting the measured metal element contents into Formula 1 to calculate the metal element content of the current contamination center of the silicon wafer to be measured and the distance from each point to the contamination center of the silicon wafer to be measured; locking the contamination center of the silicon wafer to be measured according to the position of each point and its distance from the contamination center of the silicon wafer to be measured.
[0009] In some embodiments, the method for detecting metal contamination of a silicon wafer further includes: obtaining the environmental characteristics of the silicon wafer to be measured; constructing Formula 2, which is used to reflect the law of change of the metal element content of the contamination center of the silicon wafer to be measured over time in the environmental characteristics; after determining the metal element content of the current contamination center of the silicon wafer to be measured, leaving the silicon wafer to be measured stationary and recording the stationary time; detecting the metal element content of the contamination center of the silicon wafer to be measured after standing; combining Formula 1 to calculate the initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time; the initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time are combined with Formula 1 and Formula 2 to predict the metal element content at any position on the first surface of the silicon wafer to be measured at any time in the environmental characteristics.
[0010] The above method for detecting metal contamination of a silicon wafer can not only infer the initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time, but also predict the metal element content at any position on the first surface of the silicon wafer to be measured at any time in the environmental characteristics. It is not necessary to perform regular repeated detections on different positions on the first surface of the silicon wafer to be measured, effectively reducing the number of detections, shortening the detection time, improving the detection efficiency, and improving the overall level of detecting metal contamination of the silicon wafer.
[0011] In some embodiments, the steps of constructing Formula 2 include: providing a preliminary silicon wafer, which has the same doping concentration and doping type as the silicon wafer to be measured and is free of metal contamination; removing the oxide film on the surface of the preliminary silicon wafer; dropping a metal standard solution on the surface of the preliminary silicon wafer and drying it to contaminate the preliminary silicon wafer with metal, and the position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer; after contaminating the preliminary silicon wafer with metal, detecting the metal element content at the contamination center of the preliminary silicon wafer and starting timing; performing physical treatment on the preliminary silicon wafer to diffuse the metal elements in the preliminary silicon wafer, and the environmental characteristics of the physical treatment are the same as those of the silicon wafer to be measured; after performing physical treatment on the preliminary silicon wafer, detecting the metal element content at the contamination center of the preliminary silicon wafer; repeating the steps of performing physical treatment and detecting the metal element content at the contamination center of the preliminary silicon wafer to obtain a number of second data sets, where each second data set includes the metal element content at the contamination center of the preliminary silicon wafer and the corresponding time point; fitting the data of the number of second data sets to obtain Formula 2.
[0012] In some embodiments, the silicon wafer metal contamination detection method further includes: when detecting the metal element content at the contamination center of the preliminary silicon wafer, also detecting the metal element content at a plurality of points on the side of the contamination center of the preliminary silicon wafer to determine the edge of the metal element diffusion region; calculating the time interval between adjacent time points and the corresponding diffusion length, where the diffusion length is the distance between the edges of the metal element diffusion regions corresponding to adjacent time points, and the ratio of the diffusion length to the time interval is the diffusion rate of the metal element in the silicon wafer to be measured in the environmental characteristics.
[0013] In some embodiments, the silicon wafer metal contamination detection method further includes: when detecting the metal element content at the contamination center of the preliminary silicon wafer, also detecting the metal element content at the following points: the point on the second surface of the preliminary silicon wafer corresponding to the contamination center of the preliminary silicon wafer, a plurality of first points on the side of the contamination center of the preliminary silicon wafer, and the second points on the second surface of the preliminary silicon wafer corresponding to the first points; obtaining the distribution law of the metal elements on the second surface according to the detection results.
[0014] In some embodiments, the silicon wafer metal contamination detection method further includes: after removing the oxide film on the surface of the preliminary silicon wafer and before dropping the metal standard solution on the surface of the preliminary silicon wafer, detecting the metal element content at a plurality of points on the surface of the preliminary silicon wafer to determine that the preliminary silicon wafer is free of metal contamination.
[0015] In some embodiments, the physical treatment includes standing at room temperature and standing with heating.
[0016] In some embodiments, the content of metal elements is detected by a total reflection X-ray fluorescence spectrometer.
[0017] In a second aspect, the present invention provides a silicon wafer metal contamination detection device, comprising:
[0018] A silicon wafer processing module, configured to: remove the oxide film on the surface of a preliminary silicon wafer, the preliminary silicon wafer being free of metal contamination and having the same doping type as the silicon wafer to be measured; drop a metal standard solution on the surface of the preliminary silicon wafer and dry it to contaminate the preliminary silicon wafer with metal, and the position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer; perform physical treatment on the preliminary silicon wafer to diffuse the metal elements in the preliminary silicon wafer;
[0019] A detection module, configured to: detect the content of metal elements at a plurality of points at the contamination center and the side thereof of the preliminary silicon wafer, and measure the distance from each point to the contamination center of the preliminary silicon wafer to obtain a number of first data sets; detect the content of metal elements at at least three preset points on the first surface of the current silicon wafer to be measured, the first surface having a contamination center;
[0020] A calculation and fitting module, configured to: fit the data of a number of the first data sets to obtain Formula 1; use Formula 1 and the content of metal elements at at least three of the preset points to calculate the content of metal elements at the contamination center of the current silicon wafer to be measured and the distance from each preset point to the contamination center of the silicon wafer to be measured; lock the contamination center of the silicon wafer to be measured according to the position of each preset point and its distance from the contamination center of the silicon wafer to be measured; according to the content of metal elements at the contamination center of the current silicon wafer to be measured and the position of the contamination center of the silicon wafer to be measured, and in combination with Formula 1, obtain the content of metal elements at any position on the first surface of the current silicon wafer to be measured.
[0021] In the silicon wafer metal contamination detection method of the present application, Formula 1 is constructed before detecting the silicon wafer to be measured. After substituting the content of metal elements at the contamination center of the current silicon wafer to be measured into Formula 1, the exact relationship satisfied by the content of metal elements at any position on the first surface of the silicon wafer to be measured and the contamination center of the silicon wafer to be measured in the current state can be obtained. After determining the contamination center of the silicon wafer to be measured, in combination with the above exact relationship, the content of metal elements at any position on the first surface of the current silicon wafer to be measured can be calculated. Only by determining the content of metal elements at the contamination center of the silicon wafer to be measured can the content of metal elements at any position on the surface of the current silicon wafer to be measured be obtained in a timely and effective manner, without the need to detect each position, which reduces the number of detections, shortens the detection time, and improves the detection efficiency. Description of the Drawings
[0022] To more clearly illustrate the technical solutions in the embodiments of the present application or in the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.
[0023] Figure 1 It is a flowchart of a silicon wafer metal contamination detection method provided in an embodiment.
[0024] Figure 2 It is a flowchart of constructing Formula 1 provided in an embodiment.
[0025] Figure 3 It is a flowchart of determining the position of the contamination center of the silicon wafer to be measured and the metal element content of the current contamination center of the silicon wafer to be measured provided in an embodiment.
[0026] Figure 4 It is a flowchart of a silicon wafer metal contamination detection method provided in another embodiment.
[0027] Figure 5 It is a flowchart of constructing Formula 2 provided in an embodiment.
[0028] Figure 6 It is a schematic diagram after dropping a metal standard solution on the surface of a preliminary silicon wafer provided in an embodiment.
[0029] Figure 7 It is a schematic diagram of the point distribution for detecting the metal element content on the first surface of a preliminary silicon wafer before physical treatment of the preliminary silicon wafer provided in an embodiment.
[0030] Figure 8 It is a schematic diagram of the point distribution for detecting the metal element content on the first surface of a preliminary silicon wafer after physical treatment of the preliminary silicon wafer provided in an embodiment.
[0031] Figure 9 It is a schematic diagram of the metal element distribution on the first surface of a preliminary silicon wafer after physical treatment of the preliminary silicon wafer provided in an embodiment.
[0032] Figure 10 It is a schematic diagram of the metal element distribution of the cross-section of a preliminary silicon wafer after physical treatment of the preliminary silicon wafer provided in an embodiment.
[0033] Figure 11 It is a schematic diagram of the point distribution for detecting the metal element content on the first surface of a preliminary silicon wafer before dropping a metal standard solution on the surface of the preliminary silicon wafer provided in an embodiment.
[0034] Figure 12It is a structural block diagram of a silicon wafer metal contamination detection device provided in an embodiment;
[0035] Explanation of reference numerals:
[0036] 1 - Preliminary silicon wafer; 11 - Metal standard solution; 12 - Contamination center; 13 - Point; 2 - Silicon wafer processing module; 3 - Detection module; 4 - Calculation and fitting module. Specific implementation manner
[0037] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.
[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.
[0039] Silicon wafer metal contamination detection is an important link in the production control of semiconductor wafers. The degree of metal contamination of silicon wafers directly affects the quality of the final products. Metal impurity contamination of silicon wafers will directly lead to deterioration of the breakdown voltage of the gate oxide film, an increase in the reverse leakage current of the PN junction, poor breakdown voltage of the insulating film, and a reduction in the minority carrier lifetime. Different metal elements have different behaviors after contacting the silicon wafer. For example, easily diffusible metal elements such as Cu, Fe, Ni, etc. can diffuse rapidly in the silicon wafer, and their diffusion rates are also affected by the environment where the silicon wafer is located, as well as the doping type and doping concentration of the silicon wafer, increasing the difficulty of silicon wafer metal contamination detection.
[0040] As described in the background art, existing silicon wafer metal contamination detection methods are difficult to detect the metal element content at different positions on the silicon wafer surface in a timely and effective manner. Specifically, existing silicon wafer metal contamination detection methods include total reflection X-ray fluorescence spectrometers (TXRF), and TXRF can perform fixed-point detection and is non-destructive. When using TXRF to detect the metal element content at different positions on the silicon wafer surface, it is necessary to detect different positions on the silicon wafer surface in sequence. Therefore, the number of detections is large and the detection time is long, and it is impossible to obtain the metal element content at different positions on the silicon wafer surface in a timely and effective manner.
[0041] Based on this, referring to Figure 1 , the present invention provides a silicon wafer metal contamination detection method, including:
[0042] Step S1, provide a silicon wafer to be tested, the silicon wafer to be tested has a first surface and a second surface arranged opposite to each other, and the first surface has a contamination center;
[0043] Step S2: Construct Formula 1, which is used to reflect the relationship between the metal element content at any position on the first surface of the silicon wafer to be measured and the pollution center of the silicon wafer to be measured.
[0044] Step S3: Determine the position of the pollution center of the silicon wafer to be measured and the metal element content at the current pollution center of the silicon wafer to be measured, and combine Formula 1 to obtain the metal element content at any position on the first surface of the current silicon wafer to be measured.
[0045] Specifically, Formula 1 contains two associated variables, namely the metal element content at any position on the first surface of the silicon wafer to be measured and the distance between any position on the first surface of the silicon wafer to be measured and the pollution center of the silicon wafer to be measured, and also contains an uncertain value, which is the metal element content at the pollution center of the silicon wafer to be measured. Formula 1 is constructed before detecting the silicon wafer to be measured. After substituting the metal element content at the current pollution center of the silicon wafer to be measured into Formula 1, the exact relationship satisfied by the metal element content at any position on the first surface of the silicon wafer to be measured and the pollution center of the silicon wafer to be measured in the current state can be obtained. After determining the pollution center of the silicon wafer to be measured, the metal element content at any position on the first surface of the current silicon wafer to be measured can be calculated in combination with the above exact relationship. It can be seen that the above silicon wafer metal pollution detection method only needs to determine the metal element content at the pollution center of the silicon wafer to be measured to obtain the metal element content at any position on the surface of the current silicon wafer to be measured in a timely and effective manner, without the need to detect each position, which reduces the number of detections, shortens the detection time, and improves the detection efficiency.
[0046] It should be noted that different metal elements correspond to different Formula 1. That is, when there are multiple metal elements in the silicon wafer to be measured, one Formula 1 is only used to reflect the relationship between the metal element content of one kind at any position on the first surface of the silicon wafer to be measured and the pollution center of the silicon wafer to be measured, and cannot reflect the relationship between the total metal element content at any position on the first surface of the silicon wafer to be measured and the pollution center of the silicon wafer to be measured. When there is only one metal element in the silicon wafer to be measured, the metal element content at any position on the first surface of the current silicon wafer to be measured can be obtained by using one Formula 1; when there are multiple metal elements in the silicon wafer to be measured, it is necessary to determine the content of each metal element at the current pollution center of the silicon wafer to be measured respectively, and construct multiple Formula 1 correspondingly to obtain the metal element content at any position on the first surface of the current silicon wafer to be measured.
[0047] It should be understood that the pollution center is the original pollution point of the point pollution type, and it is also the point with the largest metal element content on the silicon wafer surface.
[0048] In some embodiments, refer to Figure 2 , the steps of constructing Formula 1 in Step S2 include:
[0049] Step S21: Provide a preliminary silicon wafer, which is free of metal pollution and has the same doping type as the silicon wafer to be measured.
[0050] Step S22: Remove the oxide film on the surface of the preliminary silicon wafer;
[0051] Step S23: Drop a metal standard solution on the surface of the preliminary silicon wafer and dry it to contaminate the preliminary silicon wafer with metal. The position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer, and the contamination center of the preliminary silicon wafer is unique;
[0052] Figure 6 The schematic diagram of dropping the metal standard solution 11 on the surface of the preliminary silicon wafer 1 is shown, and the contamination center 12 is shown;
[0053] Step S24: Physically process the preliminary silicon wafer to make the metal elements in the preliminary silicon wafer diffuse in a direction away from the contamination center of the preliminary silicon wafer;
[0054] Step S25: Detect the metal element contents at multiple points in the contamination center of the preliminary silicon wafer and its side, and measure the distances from the points to the contamination center of the preliminary silicon wafer to obtain a number of first data sets. Each first data set includes the metal element content and the distance from the corresponding point to the contamination center of the preliminary silicon wafer;
[0055] Step S26: Fit the data of the number of first data sets to obtain Formula 1.
[0056] Specifically, in step S23, there is and contains only one metal element in the metal standard solution, and this metal element exists in the silicon wafer to be measured. After contaminating the preliminary silicon wafer with metal, there is one metal element in the preliminary silicon wafer; when there are multiple metal elements in the silicon wafer to be measured, multiple preliminary silicon wafers need to be provided, and different metal standard solutions are dropped on each preliminary silicon wafer to construct Formula 1 corresponding to each metal element. Removing the oxide film on the surface of the preliminary silicon wafer in step S22 is beneficial for the metal elements in the metal standard solution to enter the silicon wafer and can avoid the influence of the existence of the oxide film on the detection of the metal element content.
[0057] Specifically, Formula 1 is as follows: S0 = A0x -b + C; where x is the distance between any position on the surface of the preliminary silicon wafer and the contamination center of the preliminary silicon wafer, with the unit of millimeter (mm), S0 is the metal element content at any position on the current surface of the preliminary silicon wafer, A0 is the metal element content at the contamination center of the current preliminary silicon wafer, with the unit of atoms / cm 2, both b and C are constants, and the value of b is related to the doping type of the preliminary silicon wafer and the type of metal element. It should be noted that since the metal element content at the pollution center of the silicon wafer to be measured is different from that at the pollution center of the preliminary silicon wafer, the relationship of the metal element content at any position on the first surface of the silicon wafer to be measured does not fully satisfy the formula one obtained in step S26. After determining the position of the pollution center of the silicon wafer to be measured and the metal element content A of the current pollution center of the silicon wafer to be measured, it is necessary to replace A0 in the formula one obtained in step S26 with the metal element content A of the current pollution center of the silicon wafer to be measured. The metal element content at any position on the first surface of the silicon wafer to be measured satisfies the finally obtained formula S = Ax -b +C, where x is the distance between any position on the first surface of the silicon wafer to be measured and the pollution center of the silicon wafer to be measured, and S is the metal element content at any position on the first surface of the current silicon wafer to be measured. Combining the position of the pollution center of the silicon wafer to be measured with this formula can determine the metal element content at any position on the first surface of the current silicon wafer to be measured.
[0058] In some embodiments, referring to Figure 3 , the steps of step S3 for determining the position of the pollution center of the silicon wafer to be measured and the metal element content of the current pollution center of the silicon wafer to be measured include:
[0059] Step S31: Detect the metal element content at at least three points on the first surface of the current silicon wafer to be measured;
[0060] Step S32: Substitute the measured metal element content into formula one to obtain a system of equations, and solve the above system of equations to obtain the metal element content A of the current pollution center of the silicon wafer to be measured and the distance x between each point and the pollution center of the silicon wafer to be measured;
[0061] Step S33: Lock the pollution center of the silicon wafer to be measured according to the position of each point and its distance from the pollution center of the silicon wafer to be measured.
[0062] It should be noted that when the silicon wafer to be measured contains multiple metal elements, the metal element content of the current pollution center of the silicon wafer to be measured determined in step S3 corresponds to the content of one metal element, rather than the total metal element content of the current pollution center of the silicon wafer to be measured; correspondingly, the content of the same metal element is also detected in step S31. When the silicon wafer to be measured contains multiple metal elements, after determining the position of the pollution center of the silicon wafer to be measured, the content of other metal elements at the pollution center of the silicon wafer to be measured can be detected, and then combined with the corresponding formula one to obtain the content of this metal element at any position on the first surface of the current silicon wafer to be measured.
[0063] Specifically, the multiple metal element content values substituted into Formula 1 in step S32 can be different from each other, or some of the metal element content values can be the same. By way of example, when the metal element content of three points is detected in step S31 and the metal element content values of the first point and the second point are the same, the pollution center of the silicon wafer to be measured is located on the perpendicular bisector of the first point and the second point. The pollution center of the silicon wafer to be measured can be locked based on the positions of the three points and their distances from the pollution center x of the silicon wafer to be measured. As a special case, if there are three or more identical values among the multiple metal element contents obtained in step S31, the pollution center of the silicon wafer to be measured is located at the center of the circle formed by these three points.
[0064] As a specific example, step S31 can take nine points, and the nine points are arranged in a cross shape, that is, there are 5 points arranged in sequence and at equal intervals in the first direction, and 5 points arranged in sequence and at equal intervals in the second direction. The first direction is perpendicular to the second direction, and the center point of the first direction is the same as the center point of the second direction; the approximate area of the pollution center of the silicon wafer to be measured can be predicted according to the trend of the metal element content of each point in the same direction.
[0065] It should be noted that it is difficult to accurately find the pollution center of the silicon wafer by the existing silicon wafer metal pollution detection method, and the silicon wafer metal pollution detection method provided in this embodiment can quickly and accurately find the pollution center of the silicon wafer.
[0066] In some embodiments, referring to Figure 4 , the silicon wafer metal pollution detection method further includes:
[0067] Step S4, obtaining the environmental characteristics of the silicon wafer to be measured;
[0068] Step S5, constructing Formula 2, which is used to reflect the law of the change of the metal element content of the pollution center of the silicon wafer to be measured with time under the above environmental characteristics;
[0069] After determining the metal element content of the current pollution center of the silicon wafer to be measured, let the silicon wafer to be measured stand still, record the standing time; detect the metal element content of the pollution center of the silicon wafer to be measured after standing still; calculate the initial pollution time t0 of the silicon wafer to be measured and the metal element content A of the pollution center of the silicon wafer to be measured at the initial pollution time in combination with Formula 1;
[0070] Based on the initial pollution time t0 of the silicon wafer to be measured and the metal element content A of the pollution center of the silicon wafer to be measured at the initial pollution time, combine Formula 1 and Formula 2 to predict the metal element content at any position on the first surface of the silicon wafer to be measured at any time under the environmental characteristics.
[0071] Specifically, the initial contamination time t0 of the silicon wafer to be measured and the metal element content A of the contamination center of the silicon wafer to be measured at the initial contamination time can be calculated using the metal element content of the contamination center of the silicon wafer to be measured before and after standing; Formula 2 contains two related variables, namely, the contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured in the environmental characteristics, and also contains an uncertain value, i.e., the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time. Formula 2 is constructed before detecting the silicon wafer to be measured; after substituting the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time into Formula 2, the exact law of the change of the metal element content of the contamination center of the silicon wafer to be measured in the environmental characteristics with time can be obtained. Combining with the initial contamination time t0 of the silicon wafer to be measured, the metal element content of the contamination center of the silicon wafer to be measured in the environmental characteristics at different times can be predicted; further, after determining the metal element content of the contamination center of the silicon wafer to be measured at different times, combining with the exact relationship satisfied by the metal element content at any position on the first surface of the silicon wafer to be measured and the contamination center of the silicon wafer to be measured obtained in step S3, the metal element content at any position on the first surface of the silicon wafer to be measured in the environmental characteristics at any time can be determined.
[0072] The above silicon wafer metal contamination detection method can not only infer the initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time, but also predict the metal element content at any position on the first surface of the silicon wafer to be measured in the environmental characteristics at any time, without the need for regular repeated detection of different positions on the first surface of the silicon wafer to be measured, effectively reducing the number of detections, shortening the detection time, improving the detection efficiency, and improving the overall silicon wafer metal contamination detection level.
[0073] Specifically, in step S4, the environmental characteristics refer to characteristics that can affect the metal diffusion rate, such as temperature, humidity, etc.
[0074] It should be noted that in step S5, different metal elements correspond to different Formula 2. That is, when the silicon wafer to be measured contains multiple metal elements, one Formula 2 is only used to reflect the law of the change of the content of one metal element of the contamination center of the silicon wafer to be measured in the above environmental characteristics with time, and cannot reflect the law of the change of the total metal element content of the contamination center of the silicon wafer to be measured in the above environmental characteristics with time. When the silicon wafer to be measured contains only one metal element, the law of the change of the metal element content of the contamination center of the silicon wafer to be measured in the above environmental characteristics with time can be obtained using one Formula 2; when the silicon wafer to be measured contains multiple metal elements, multiple Formula 2 need to be constructed corresponding to each metal element, and the content of each metal element of the contamination center of the silicon wafer to be measured at the initial contamination time needs to be determined respectively, so as to predict the metal element content at any position on the first surface of the silicon wafer to be measured in the environmental characteristics at any time by combining the corresponding Formula 1 and Formula 2.
[0075] In some embodiments, referring to Figure 5 , the steps of constructing Formula 2 in step S5 include:
[0076] Step S51: Provide a preliminary wafer. The doping concentration and doping type of the preliminary wafer are the same as those of the wafer to be measured, and the preliminary wafer is free of metal contamination;
[0077] Step S52: Remove the oxide film on the surface of the preliminary wafer;
[0078] Step S53: Drop a metal standard solution on the surface of the preliminary wafer and dry it to contaminate the preliminary wafer with metal. The position where the metal standard solution is dropped is the contamination center of the preliminary wafer, and the contamination center of the preliminary wafer is unique;
[0079] Figure 6 shows a schematic diagram of dropping a metal standard solution 11 on the surface of the preliminary wafer 1 and shows the contamination center 12;
[0080] Step S54: After contaminating the preliminary wafer with metal, detect the metal element content at the contamination center of the preliminary wafer and start timing;
[0081] Step S55: Physically process the preliminary wafer to diffuse the metal elements in the preliminary wafer. The environmental characteristics of the physical process are the same as those of the wafer to be measured;
[0082] Step S56: After physically processing the preliminary wafer, detect the metal element content at the contamination center of the preliminary wafer;
[0083] Step S57: Repeat the steps of physically processing and detecting the metal element content at the contamination center of the preliminary wafer to obtain a number of second data sets. The second data sets include the metal element content at the contamination center of the preliminary wafer and the corresponding time points;
[0084] Step S58: Fit the data of a number of second data sets to obtain Formula 2.
[0085] In step S53, the metal standard solution contains one and only one metal element, and this metal element exists in the wafer to be measured. After contaminating the preliminary wafer with metal, the preliminary wafer contains one metal element; when the wafer to be measured contains multiple metal elements, multiple preliminary wafers need to be provided, and different metal standard solutions are dropped on each preliminary wafer to construct Formula 2 corresponding to each metal element. In step S55, the physical processing includes but is not limited to standing at room temperature and standing by heating.
[0086] Specifically, Formula 2 is as follows: A y = A y (Kt) -d+E; where t is the pollution time, in hours (h); A y is the metal element content of the pollution center of the preliminary silicon wafer at the initial pollution time, in atoms / cm 2 ; A y is the metal element content of the pollution center of the preliminary silicon wafer at different time points. K, d, and E are all constants. It should be noted that since the metal element content of the pollution center of the silicon wafer to be measured is different from that of the pollution center of the preliminary silicon wafer, the law of the metal element content of the pollution center of the silicon wafer to be measured changing with time in the environmental characteristics does not exactly satisfy Formula Two obtained in Step S58. After determining the initial pollution time t0 of the silicon wafer to be measured and the metal element content A of the pollution center of the silicon wafer to be measured at the initial pollution time in Step S3, it is necessary to replace A in Formula Two obtained in Step S58 with the metal element content A of the pollution center of the silicon wafer to be measured at the initial pollution time y , starting from the initial pollution time t0 of the silicon wafer to be measured, the law of the metal element content of the pollution center of the silicon wafer to be measured changing with time in the environmental characteristics satisfies the finally obtained formula A = A(Kt) -d +E. At this time, t is the pollution time of the silicon wafer to be measured, and t = 0 corresponds to the initial pollution time t0 of the silicon wafer to be measured.
[0087] It should be understood that the diffusion rate of the same metal element varies greatly in silicon wafers of different doping types and also in silicon wafers of different doping concentrations. At the same time, the diffusion rate of metal elements is also affected by the environment. In order to make Formula Two obtained in Step S58 accurately reflect the law of the metal element content of the pollution center of the silicon wafer to be measured changing with time in the environmental characteristics, it is necessary to control the doping concentration and doping type of the preliminary silicon wafer and the silicon wafer to be measured to be the same, and the environmental characteristics of the physical treatment of the preliminary silicon wafer and the environmental characteristics of the silicon wafer to be measured to be the same.
[0088] In some embodiments, the silicon wafer metal pollution detection method further includes: when detecting the metal element content of the pollution center of the preliminary silicon wafer in Step S56, also detecting the metal element content of multiple points 13 on the side of the pollution center of the preliminary silicon wafer to determine the edge of the metal element diffusion region Figure 7 shows the schematic diagram of the point distribution for detecting the metal element content on the first surface of the preliminary silicon wafer before the physical treatment of the preliminary silicon wafer Figure 8It shows a schematic diagram of the point distribution for detecting the metal element content on the first surface of a preliminary silicon wafer after physical treatment of the preliminary silicon wafer; calculate the time interval between adjacent time points and the corresponding diffusion length. The diffusion length is the distance between the edges of the metal element diffusion regions corresponding to adjacent time points, and the ratio of the diffusion length to the time interval is the diffusion rate of the metal elements in the silicon wafer to be measured in the environmental characteristics. When there are multiple metal elements in the silicon wafer to be measured, multiple preliminary silicon wafers need to be provided, and different metal standard solutions are dropped on each preliminary silicon wafer. Different diffusion rates of different metal elements can be obtained using different preliminary silicon wafers. Different metal elements have different diffusion rates in the same silicon wafer. Understanding the movement properties of metal elements in the silicon wafer helps in detecting metal contamination of the silicon wafer. For example, the type of metal elements in the silicon wafer can be determined.
[0089] As a preferred example, when detecting the metal element content at the contamination center of the preliminary silicon wafer in step S5, the metal element content at the following other points is also detected: the point on the second surface of the preliminary silicon wafer corresponding to the contamination center of the preliminary silicon wafer, multiple first points located on the side of the contamination center of the preliminary silicon wafer, and the second points on the second surface of the preliminary silicon wafer corresponding to the first points; determine the distribution law of the metal elements according to the detection results. Each time the metal element content at the contamination center of the preliminary silicon wafer is detected in step S5, the metal element content at other points needs to be detected, and different positions can be taken for the first points each time the metal element content at the contamination center of the preliminary silicon wafer is detected. According to the detection results, the distribution of the metal elements has the following laws: Refer to Figure 9 , the content of the easily diffusible metal elements on the first surface gradually decreases from the contamination center outwards, and as the standing time prolongs, the metal element content at the contamination center gradually decreases; Refer to Figure 10 , when the thickness of the preliminary silicon wafer is less than 1 mm, the content of the easily diffusible metal elements at the corresponding points on the first surface and the second surface is basically the same. Figure 9 - Figure 10 The black dots in [[ ]] represent metal elements. After predicting the metal element content at any position on the first surface of the silicon wafer to be measured at any time in the environmental characteristics in step S7, the metal element content distribution on the second surface of the silicon wafer to be measured can be predicted using the above laws, and the metal element content distribution inside the silicon wafer to be measured can be estimated. However, the existing methods for detecting metal contamination of silicon wafers are difficult to evaluate the metal element content on both the front and back surfaces and inside the silicon wafer.
[0090] In some embodiments, the method for detecting metal contamination of a silicon wafer further includes: after removing the oxide film on the surface of the preliminary silicon wafer and before dropping the metal standard solution on the surface of the preliminary silicon wafer, detecting the metal element content at several points on the surface of the preliminary silicon wafer to determine that the preliminary silicon wafer has no metal contamination, which is beneficial to improving the accuracy of Formula 1 and Formula 2. Figure 11The figure shows a schematic diagram of the point distribution for detecting the metal element content on the first surface of a preliminary silicon wafer before dropping a metal standard solution on the surface of the preliminary silicon wafer.
[0091] In some embodiments, a total reflection X-ray fluorescence spectrometer (TXRF) can be used to detect the metal element content. TXRF can measure the metal element content in the near-surface 1 nm - 10 nm of the silicon wafer.
[0092] The following provides an exemplary specific method for detecting metal contamination of a silicon wafer to clearly and completely illustrate the technical solution of the present application:
[0093] The silicon wafer to be tested has a first surface and a second surface that are oppositely arranged, and the first surface has a contamination center; the silicon wafer to be tested contains a metal element, and the type of the metal element is known.
[0094] I. Preparation before detecting the silicon wafer to be tested:
[0095] 1) Provide a preliminary silicon wafer, and the doping concentration and doping type of the preliminary silicon wafer are the same as those of the silicon wafer to be tested;
[0096] 2) Remove the oxide film on the surface of the preliminary silicon wafer;
[0097] 3) Detect the metal element content at several points on the surface of the preliminary silicon wafer to determine that the preliminary silicon wafer has no metal contamination;
[0098] 4) Drop a metal standard solution on the surface of the preliminary silicon wafer and dry it, so that the preliminary silicon wafer contains the metal element in the silicon wafer to be tested. The position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer, and the contamination center of the preliminary silicon wafer is unique;
[0099] 5) Use a total reflection X-ray fluorescence spectrometer to detect the metal element content at the contamination center of the preliminary silicon wafer and start timing;
[0100] 6) Let the preliminary silicon wafer stand at room temperature to allow the metal elements in the preliminary silicon wafer to diffuse. The environment where the preset silicon wafer is located is the same as the environment where the silicon wafer to be tested is located;
[0101] 7) Use a total reflection X-ray fluorescence spectrometer to detect the metal element content at the following points: the contamination center of the preliminary silicon wafer, multiple points on the side of the contamination center, and measure the distance from the point to the contamination center of the preliminary silicon wafer to obtain several first data sets. Each first data set includes the metal element content and the distance from the corresponding point to the contamination center of the preliminary silicon wafer;
[0102] 8) Repeat the steps of standing at room temperature and detecting the metal element content at the above points to obtain several second data sets. The second data sets include the metal element content at the contamination center of the preliminary silicon wafer and the corresponding time points;
[0103] 9) Fit the data of several first data groups to obtain Formula 1; fit the data of several second data groups to obtain Formula 2.
[0104] Further, all the above steps for detecting the metal element content are for detecting the points on the first surface. While detecting the points on the first surface, it is also possible to detect the metal element content of the points on the second surface, and the points on the second surface correspond to the points on the first surface; analyze the distribution law of metal elements on the first surface and the second surface according to the detection results.
[0105] Further, when detecting the metal element content of multiple points on the side of the pollution center, determine the edge of the metal element diffusion region, and the metal element content at the edge position of the metal element diffusion region is zero; the distance between the edges of the metal element diffusion region before and after standing at room temperature is the diffusion length, and the ratio of the diffusion length to the room temperature standing time is the diffusion rate of the metal elements in the silicon wafer to be measured in the environmental characteristics.
[0106] II. Conduct metal pollution detection on the silicon wafer to be measured:
[0107] 1) Detect the metal element content of at least three points on the first surface of the current silicon wafer to be measured;
[0108] 2) Substitute the measured metal element content into Formula 1 to obtain a system of equations, and calculate the metal element content at the pollution center of the current silicon wafer to be measured and the distance between each point and the pollution center of the silicon wafer to be measured;
[0109] 3) Lock the pollution center of the silicon wafer to be measured according to the position of each point and its distance from the pollution center of the silicon wafer to be measured.
[0110] 4) Let the silicon wafer to be measured stand, record the standing time; detect the metal element content at the pollution center of the silicon wafer to be measured after standing;
[0111] 5) Substitute the metal element content at the pollution center of the silicon wafer to be measured before and after standing, and the standing time into Formula 1 to obtain a system of equations, and calculate the initial pollution time t0 of the silicon wafer to be measured and the metal element content A at the pollution center of the silicon wafer to be measured at the initial pollution time;
[0112] 6) Combining the initial pollution time t0 of the silicon wafer to be measured and the metal element content A at the pollution center of the silicon wafer to be measured at the initial pollution time with Formula 1, the exact law of the change of the metal element content at the pollution center of the silicon wafer to be measured in the environmental characteristics over time can be obtained; then combining with Formula 2, predict the metal element content at any position on the first surface of the silicon wafer to be measured at any time in the environmental characteristics.
[0113] Further, according to the distribution law of metal elements, predict the metal element content distribution on the second surface of the silicon wafer to be measured, and estimate the metal element content distribution inside the silicon wafer to be measured.
[0114] In a second aspect, referring to Figure 12 , the present application provides a silicon wafer metal contamination detection device, including a silicon wafer processing module 2, a detection module 3, and a calculation and fitting module 4.
[0115] The silicon wafer processing module 2 is configured to: remove the oxide film on the surface of the preliminary silicon wafer, the preliminary silicon wafer has no metal contamination and the same doping type as the silicon wafer to be measured; drop a metal standard solution on the surface of the preliminary silicon wafer and dry it to contaminate the preliminary silicon wafer, and the position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer; perform physical treatment on the preliminary silicon wafer to diffuse the metal elements in the preliminary silicon wafer.
[0116] The detection module 3 is configured to: detect the metal element content at multiple points at the contamination center and its side of the preliminary silicon wafer, and measure the distance from the point to the contamination center of the preliminary silicon wafer to obtain a number of first data sets; detect the metal element content at at least three preset points on the first surface of the current silicon wafer to be measured, and the first surface has a contamination center.
[0117] The calculation and fitting module 4 is configured to: fit the data of a number of first data sets to obtain Formula 1; use Formula 1 and the metal element content at at least three preset points to calculate the metal element content at the contamination center of the current silicon wafer to be measured and the distance from each preset point to the contamination center of the silicon wafer to be measured; lock the contamination center of the silicon wafer to be measured according to the position of each preset point and its distance from the contamination center of the silicon wafer to be measured; according to the metal element content at the contamination center of the current silicon wafer to be measured and the position of the contamination center of the silicon wafer to be measured, combine Formula 1 to obtain the metal element content at any position on the first surface of the current silicon wafer to be measured.
[0118] In some embodiments, the doping concentration of the preliminary silicon wafer is the same as that of the silicon wafer to be measured; the environmental characteristics of the physical treatment are the same as those of the silicon wafer to be measured;
[0119] The silicon wafer processing module 2 is further configured to: repeat the physical treatment; let the silicon wafer to be measured stand still after determining the metal element content at the contamination center of the current silicon wafer to be measured;
[0120] The detection module 3 is further configured to: after contaminating the preliminary silicon wafer with metal, detect the metal element content at the contamination center of the preliminary silicon wafer and start timing; after each physical treatment of the preliminary silicon wafer, detect the metal element content at the contamination center of the preliminary silicon wafer to obtain a number of second data sets, and the second data sets include the metal element content at the contamination center of the preliminary silicon wafer and the corresponding time points; determine the standing time of the silicon wafer to be measured; detect the metal element content at the contamination center of the standing silicon wafer to be measured;
[0121] The calculation and fitting module 4 is further configured to: fit the data of a number of second data groups to obtain Formula Two; use the metal element content of the contamination center of the silicon wafer to be measured before and after standing and the standing time of the silicon wafer to be measured, and combine Formula One to calculate the initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time; the initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time are combined with Formula One and Formula Two to predict the metal element content at any position on the first surface of the silicon wafer to be measured at any time in the environmental characteristics.
[0122] In some embodiments, the detection module 3 is further configured to: when detecting the metal element content of the contamination center of the preliminary silicon wafer, also detect the metal element content of a plurality of points on the side of the contamination center of the preliminary silicon wafer to determine the edge of the metal element diffusion region;
[0123] The calculation and fitting module 4 is further configured to: calculate the time interval between adjacent time points and the corresponding diffusion length, where the diffusion length is the distance between the edges of the metal element diffusion regions corresponding to adjacent time points, and the ratio of the diffusion length to the time interval is the diffusion rate of the metal elements in the silicon wafer to be measured in the environmental characteristics.
[0124] In some embodiments, the detection module 3 is further configured to: when detecting the metal element content of the contamination center of the preliminary silicon wafer, also detect the metal element content of the following points: the point on the second surface of the preliminary silicon wafer corresponding to the contamination center of the preliminary silicon wafer, a plurality of first points on the side of the contamination center of the preliminary silicon wafer, and the second points on the second surface of the preliminary silicon wafer corresponding to the first points;
[0125] The calculation and fitting module 4 is further configured to: obtain the distribution law of the metal elements on the second surface according to the detection results.
[0126] In the description of this specification, the descriptions referring to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.
[0127] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.
[0128] The above-described embodiments merely represent several implementation manners of the present application. The description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all fall within the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.
Claims
1. A method for detecting metal contamination on a silicon wafer, characterized in that, Including: Providing a silicon wafer to be measured, the silicon wafer to be measured having a first surface and a second surface disposed opposite to each other, and the first surface having a contamination center; Constructing Formula 1, which is used to reflect the relationship between the metal element content at any position on the first surface of the silicon wafer to be measured and the contamination center of the silicon wafer to be measured; Determining the position of the contamination center of the silicon wafer to be measured and the metal element content of the current contamination center of the silicon wafer to be measured, and combining Formula 1 to obtain the metal element content at any position on the first surface of the current silicon wafer to be measured.
2. The method for detecting metal contamination of a silicon wafer according to claim 1, characterized in that The steps of constructing Formula 1 include: Providing a preliminary silicon wafer, the preliminary silicon wafer being free of metal contamination and having the same doping type as the silicon wafer to be measured; Removing the oxide film on the surface of the preliminary silicon wafer; Dropping a metal standard solution on the surface of the preliminary silicon wafer and drying it to contaminate the preliminary silicon wafer with metal, and the position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer; Performing physical treatment on the preliminary silicon wafer to diffuse the metal elements in the preliminary silicon wafer; Detecting the metal element content at multiple points of the contamination center and its side of the preliminary silicon wafer, and measuring the distance from the point to the contamination center of the preliminary silicon wafer to obtain a number of first data sets; Fitting the data of a number of the first data sets to obtain Formula 1.
3. The silicon wafer metal contamination detection method according to claim 1, characterized in that, The steps of determining the position of the contamination center of the silicon wafer to be measured and the metal element content of the current contamination center of the silicon wafer to be measured include: Detecting the metal element content at at least three points on the first surface of the current silicon wafer to be measured; Substituting the measured metal element content into Formula 1 to calculate the metal element content of the current contamination center of the silicon wafer to be measured and the distance from each point to the contamination center of the silicon wafer to be measured; Locking the contamination center of the silicon wafer to be measured according to the position of each point and its distance from the contamination center of the silicon wafer to be measured.
4. The method for detecting metal contamination of a silicon wafer according to claim 1, wherein Also including: Obtaining the environmental characteristics of the silicon wafer to be measured; Constructing Formula 2, which is used to reflect the law of change of the metal element content of the contamination center of the silicon wafer to be measured with time in the environmental characteristics; After determining the metal element content of the current contamination center of the silicon wafer to be measured, standing the silicon wafer to be measured and recording the standing time; detecting the metal element content of the contamination center of the silicon wafer to be measured after standing; combining Formula 1 to calculate the initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time; The initial contamination time of the silicon wafer to be measured and the metal element content of the contamination center of the silicon wafer to be measured at the initial contamination time are combined with Formula 1 and Formula 2 to predict the metal element content at any position on the first surface of the silicon wafer to be measured at any time in the environmental characteristics.
5. The method for detecting metal contamination of a silicon wafer according to claim 4, wherein The steps of constructing Formula 2 include: Providing a preliminary silicon wafer, the preliminary silicon wafer having the same doping concentration and doping type as the silicon wafer to be measured, and the preliminary silicon wafer being free of metal contamination; Removing the oxide film on the surface of the preliminary silicon wafer; Dropping a metal standard solution on the surface of the preliminary silicon wafer and drying it to contaminate the preliminary silicon wafer with metal, and the position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer; After metal contamination of the preliminary silicon wafer, detect the metal element content at the contamination center of the preliminary silicon wafer and start timing; Physically process the preliminary silicon wafer to diffuse the metal elements in the preliminary silicon wafer, and the environmental characteristics of the physical process are the same as those of the silicon wafer to be measured; After physically processing the preliminary silicon wafer, detect the metal element content at the contamination center of the preliminary silicon wafer; Repeat the steps of physically processing the preliminary silicon wafer and detecting the metal element content at the contamination center of the preliminary silicon wafer to obtain a number of second data sets, where each second data set includes the metal element content at the contamination center of the preliminary silicon wafer and the corresponding time point; Fit the data of a number of the second data sets to obtain Formula 2.
6. The method for detecting metal contamination of a silicon wafer according to claim 5, wherein, It further includes: When detecting the metal element content at the contamination center of the preliminary silicon wafer, also detect the metal element content at multiple points on the side of the contamination center of the preliminary silicon wafer to determine the edge of the metal element diffusion region; Calculate the time interval between adjacent time points and the corresponding diffusion length. The diffusion length is the distance between the edges of the metal element diffusion regions corresponding to adjacent time points. The ratio of the diffusion length to the time interval is the diffusion rate of the metal element in the silicon wafer to be measured in the environmental characteristics.
7. The method for detecting metal contamination of a silicon wafer according to claim 5, wherein It further includes: When detecting the metal element content at the contamination center of the preliminary silicon wafer, also detect the metal element content at the following points: the point on the second surface of the preliminary silicon wafer corresponding to the contamination center of the preliminary silicon wafer, multiple first points on the side of the contamination center of the preliminary silicon wafer, and second points on the second surface of the preliminary silicon wafer corresponding to the first points; Obtain the distribution law of the metal elements on the second surface according to the detection results.
8. The method for detecting metal contamination of a silicon wafer according to claim 2 or 5, characterized in that, It further includes: After removing the oxide film on the surface of the preliminary silicon wafer and before dropping the metal standard solution on the surface of the preliminary silicon wafer, detect the metal element content at several points on the surface of the preliminary silicon wafer to determine that the preliminary silicon wafer has no metal contamination.
9. The method for detecting metal contamination of a silicon wafer according to claim 2 or 5, characterized in that, The physical process includes static placement at room temperature and static placement by heating.
10. A silicon wafer metal contamination detection device, characterized in that, It includes: A silicon wafer processing module configured to: remove the oxide film on the surface of the preliminary silicon wafer, where the preliminary silicon wafer has no metal contamination and has the same doping type as the silicon wafer to be measured; Drop a metal standard solution on the surface of the preliminary silicon wafer and dry it. The position where the metal standard solution is dropped is the contamination center of the preliminary silicon wafer; physically process the preliminary silicon wafer to diffuse the metal elements in the preliminary silicon wafer; A detection module configured to: detect the metal element content at the contamination center of the preliminary silicon wafer and at multiple points on its side, and measure the distance from the points to the contamination center of the preliminary silicon wafer to obtain a number of first data sets; detect the metal element content at at least three preset points on the first surface of the current silicon wafer to be measured, where the first surface has a contamination center; The calculation and fitting module is configured to: fit the data of a number of the first data groups to obtain Formula 1; calculate the metal element content of the current pollution center of the silicon wafer to be measured and the distance between each preset point and the pollution center of the silicon wafer to be measured by using Formula 1 and the metal element contents of at least three of the preset points; lock the pollution center of the silicon wafer to be measured according to the position of each preset point and its distance from the pollution center of the silicon wafer to be measured; and obtain the metal element content at any position on the first surface of the current silicon wafer to be measured by combining Formula 1 based on the metal element content of the current pollution center of the silicon wafer to be measured and the position of the pollution center of the silicon wafer to be measured.