Method and device for measuring width of transition region of epitaxial silicon wafer
By measuring the resistivity data of different depths of epitaxial silicon wafers, generating resistivity curves and calculating the intersection difference value, the problem that the prior art cannot effectively measure the transition zone width of the epitaxial silicon wafer is solved, and accurate evaluation of wafer quality and optimization of electrical performance are achieved.
Patent Information
- Application Number
- CN202510109195.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-23
- Publication Date
- 2025-06-13
AI Technical Summary
The prior art has failed to effectively measure the transition zone width of epitaxial silicon wafers, which has an important impact on evaluating wafer quality and affecting the electrical performance of the final product.
By obtaining resistivity data at different depths of epitaxial silicon wafers, a resistivity curve is generated, the slope of each position point on the resistivity curve is determined, and the tangent line at the target position point with the largest slope is found. Then, select the resistivity curve of the preset depth range, generate a straight line, determine the intersection point between the tangent line and the straight line, and calculate the horizontal coordinate difference of the intersection point to obtain the thickness of the epitaxial layer.
The accurate measurement of the transition zone width of the epitaxial silicon wafer is achieved, providing a basis for evaluating wafer quality, and thus affecting the electrical performance of the final product.
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Figure CN120149183A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor manufacturing, and particularly to a method and device for measuring the width of a transition region of an epitaxial silicon wafer. Background Art
[0002] Epitaxial growth refers to a process of growing a single-crystal thin film (with the crystal direction being the same as that of the substrate crystal) on a single-crystal silicon substrate through epitaxy technology. The entire production process of an epitaxial silicon wafer includes crystal growth (pulling a silicon crystal rod from polysilicon material) → shaping (slicing and grinding) → polishing (double-sided polishing) → cleaning (removing surface particles, metal ions, and organic substances) → epitaxy (chemical vapor deposition), among which epitaxy, as the last important process, can improve the crystal properties, native defects, resistivity, and flatness of the polished wafer.
[0003] The width of the transition region of an epitaxial silicon wafer directly affects key parameters such as the breakdown voltage, forward voltage drop, reverse voltage drop, and reverse recovery time of the final product. However, the prior art does not disclose how to effectively measure the width of the transition region. Summary of the Invention
[0004] To solve the above technical problems, the present invention provides a method and device for measuring the width of a transition region of an epitaxial silicon wafer, which can accurately measure the width of the transition region of the epitaxial silicon wafer.
[0005] To achieve the above object, the technical solution adopted in the embodiment of the present invention is:
[0006] A method for measuring the width of a transition region of an epitaxial silicon wafer, comprising:
[0007] Obtaining resistivity data at different depths of an epitaxial silicon wafer, generating a resistivity curve based on the resistivity data, where the abscissa of the resistivity curve is the depth of the epitaxial silicon wafer and the ordinate is the corresponding resistivity;
[0008] Determining the slope of each position point on the resistivity curve, and determining the tangent at the target position point with the maximum slope;
[0009] Selecting the resistivity curve corresponding to a first preset depth range, generating a first straight line based on the resistivity curve of the first preset depth range, selecting the resistivity curve corresponding to a second preset depth range, and generating a second straight line based on the resistivity curve of the second preset depth range, where the depths in the first preset depth range are all less than the depth of the target position point, and the depths in the second preset depth range are all greater than the depth of the target position point;
[0010] Determining a first intersection point of the tangent with the first straight line and a second intersection point of the tangent with the second straight line;
[0011] Subtract the abscissas of the first intersection point and the second intersection point to obtain the thickness of the epitaxial layer of the epitaxial silicon wafer.
[0012] In some embodiments, the maximum depth of the first preset depth range is 75% of the depth of the epitaxial layer of the epitaxial silicon wafer, and the minimum depth of the first preset depth range is 25% of the depth of the epitaxial layer of the epitaxial silicon wafer.
[0013] In some embodiments, the second preset depth range is 6.5 - 7.5 micrometers.
[0014] In some embodiments, generating the first straight line according to the resistivity curve of the first preset depth range includes:
[0015] Select a plurality of position points on the resistivity curve of the first preset depth range;
[0016] Fit the first straight line according to the resistivity data of the plurality of position points, and the linear equation corresponding to the first straight line is y = a 1 *x + b 1 , where a 1 and b 1 are constants.
[0017] In some embodiments, generating the second straight line according to the resistivity curve of the second preset depth range includes:
[0018] Select a plurality of position points on the resistivity curve of the second preset depth range;
[0019] Calculate the average resistivity b 3 of the plurality of position points to obtain the second straight line, and the straight line equation corresponding to the second straight line is y = b 3 .
[0020] An embodiment of the present invention further provides a measuring device for the width of the transition region of an epitaxial silicon wafer, including:
[0021] A measuring module, configured to obtain resistivity data at different depths of the epitaxial silicon wafer, and generate a resistivity curve according to the resistivity data, where the abscissa of the resistivity curve is the depth of the epitaxial silicon wafer, and the ordinate is the corresponding resistivity;
[0022] A first calculation module, configured to determine the slope of each position point on the resistivity curve, and determine the tangent line at the target position point with the largest slope;
[0023] A second calculation module, configured to select the resistivity curve corresponding to the first preset depth range, generate a first straight line according to the resistivity curve of the first preset depth range, select the resistivity curve corresponding to the second preset depth range, and generate a second straight line according to the resistivity curve of the second preset depth range, wherein the depths of the first preset depth range are all less than the depth of the target position point, and the depths of the second preset depth range are all greater than the depth of the target position point;
[0024] A determination module, configured to determine a first intersection point of the tangent line and the first straight line and a second intersection point of the tangent line and the second straight line;
[0025] A third calculation module, configured to calculate the difference between the abscissas of the first intersection point and the second intersection point to obtain the thickness of the epitaxial layer of the epitaxial silicon wafer.
[0026] In some embodiments, the second calculation module is specifically configured to select a plurality of position points on the resistivity curve of the first preset depth range; fit the resistivity data of the plurality of position points to obtain the first straight line, and the linear equation corresponding to the first straight line is y = a 1 *x + b 1 where a 1 and b 1 are constants.
[0027] In some embodiments, the second calculation module is specifically configured to select a plurality of position points on the resistivity curve of the second preset depth range; calculate the average resistivity b 3 of the plurality of position points to obtain the second straight line, and the straight line equation corresponding to the second straight line is y = b 3 .
[0028] An embodiment of the present invention further provides an electronic device, including: a processor, a memory, and a program stored on the memory and executable on the processor, and when the program is executed by the processor, the steps of the method for measuring the width of the transition region of the epitaxial silicon wafer as described above are implemented.
[0029] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the method for measuring the width of the transition region of the epitaxial silicon wafer as described above are implemented.
[0030] The beneficial effects of the present invention are:
[0031] In this embodiment, resistivity data at different depths of an epitaxial silicon wafer are obtained, a resistivity curve is generated based on the resistivity data, the slope of each position point on the resistivity curve is determined, a tangent line at the target position point with the maximum slope is determined, the resistivity curve corresponding to the first preset depth range is selected, a first straight line is generated based on the resistivity curve of the first preset depth range, the resistivity curve corresponding to the second preset depth range is selected, a second straight line is generated based on the resistivity curve of the second preset depth range, and the first intersection point of the tangent line and the first straight line and the second intersection point of the tangent line and the second straight line are determined; the difference between the abscissas of the first intersection point and the second intersection point is obtained to get the thickness of the epitaxial layer of the epitaxial silicon wafer. Through the technical solution of the present invention, the width of the transition region of the epitaxial silicon wafer can be accurately measured, and thus a basis can be provided for evaluating the quality of the epitaxial silicon wafer. Description of the Drawings
[0032] Figure 1 A schematic flowchart showing the measurement method for the width of the transition region of the epitaxial silicon wafer according to an embodiment of the present invention;
[0033] Figure 2 A schematic diagram showing the resistivity curve generated according to an embodiment of the present invention;
[0034] Figure 3 A schematic diagram showing the tangent line at the target position point with the maximum slope according to an embodiment of the present invention;
[0035] Figure 4 A schematic diagram showing the intersection points of the first straight line and the second straight line fitted according to an embodiment of the present invention and the tangent line;
[0036] Figure 5 A schematic diagram showing the structure of the measurement device for the width of the transition region of the epitaxial silicon wafer according to an embodiment of the present invention;
[0037] Figure 6 A schematic diagram showing the structure of the electronic device according to an embodiment of the present invention. Detailed Embodiment
[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.
[0039] The resistivity of the epitaxial layer and the substrate layer of the epitaxial silicon wafer is different, and there is a transition region between the epitaxial layer and the substrate layer of the epitaxial silicon wafer. The width of the transition region of the epitaxial silicon wafer is an important basis for evaluating the quality of the epitaxial silicon wafer.
[0040] The present invention provides a method and device for measuring the width of the transition region of an epitaxial silicon wafer, which can accurately measure the width of the transition region of the epitaxial silicon wafer.
[0041] An embodiment of the present invention provides a method for measuring the width of the transition region of an epitaxial silicon wafer, as Figure 1 shown, including:
[0042] Step 101: Obtain resistivity data at different depths of the epitaxial silicon wafer, and generate a resistivity curve based on the resistivity data. The abscissa of the resistivity curve is the depth of the epitaxial silicon wafer, and the ordinate is the corresponding resistivity;
[0043] In this embodiment, the resistivity data at different depths of the epitaxial silicon wafer can be measured by SRP (Spreading resistance profile) test. For example, the resistivity data within the range of 0-8 micrometers of the depth of the epitaxial silicon wafer is measured, and a resistivity curve as Figure 2 shown is generated. The abscissa of the resistivity curve is the depth of the epitaxial silicon wafer, with the unit of micrometer (um); the ordinate is the corresponding resistivity, with the unit of ohm-cm.
[0044] Step 102: Determine the slope of each position point on the resistivity curve, and determine the tangent line at the target position point with the maximum slope;
[0045] In this embodiment, the slope of each position point on the resistivity curve can be obtained according to the following formula, as Figure 3 shown, and the target position point with the maximum slope on the resistivity curve is found:
[0046] Slope = (Y n - Y n-1 ) / (X n - X n-1 )
[0047] where, (X n , Y n ) and (X n-1 , Y n-1 ) are the coordinates of two adjacent points on the resistivity curve.
[0048] The obtained tangent line can be represented by the linear equation y = a 2 * x + b 2 , where a 2 and b 2 are constants.
[0049] Step 103: Select the resistivity curve corresponding to the first preset depth range, generate a first straight line according to the resistivity curve of the first preset depth range, select the resistivity curve corresponding to the second preset depth range, and generate a second straight line according to the resistivity curve of the second preset depth range. The depths of the first preset depth range are all less than the depth of the target position point, and the depths of the second preset depth range are all greater than the depth of the target position point;
[0050] In some embodiments, such as Figure 4 shown, the maximum depth of the first preset depth range may be 75% of the epitaxial layer depth of the epitaxial silicon wafer, and the minimum depth of the first preset depth range may be 25% of the epitaxial layer depth of the epitaxial silicon wafer.
[0051] Specifically, multiple position points on the resistivity curve of the first preset depth range can be selected; the first straight line is obtained by fitting the resistivity data of the multiple position points. The linear equation corresponding to the first straight line is y = a 1 *x + b 1 , where a 1 and b 1 are constants.
[0052] In some embodiments, the second preset depth range may be 6.5 - 7.5 microns. Multiple position points on the resistivity curve of the second preset depth range are selected, and the average resistivity b 3 of the multiple position points is calculated to obtain the second straight line. The straight line equation corresponding to the second straight line is y = b 3 , where b 3 is a constant.
[0053] For example, the last five position points on the resistivity curve can be selected, and the average resistivity b 3 of the five position points is calculated to obtain the second straight line.
[0054] Step 104: Determine the first intersection point of the tangent line and the first straight line and the second intersection point of the tangent line and the second straight line;
[0055] As Figure 4 shown, determine the first intersection point X1 of the tangent line and the first straight line and the second intersection point X2 of the tangent line and the second straight line.
[0056] Step 105: Subtract the abscissas of the first intersection point and the second intersection point to obtain the thickness of the epitaxial layer of the epitaxial silicon wafer.
[0057] In this embodiment, resistivity data at different depths of an epitaxial silicon wafer are obtained, a resistivity curve is generated based on the resistivity data, the slope of each position point on the resistivity curve is determined, the tangent at the target position point with the maximum slope is determined, the resistivity curve corresponding to the first preset depth range is selected, a first straight line is generated based on the resistivity curve of the first preset depth range, the resistivity curve corresponding to the second preset depth range is selected, a second straight line is generated based on the resistivity curve of the second preset depth range, the first intersection point of the tangent and the first straight line and the second intersection point of the tangent and the second straight line are determined; the abscissas of the first intersection point and the second intersection point are subtracted to obtain the thickness of the epitaxial layer of the epitaxial silicon wafer. Through the technical solution of the present invention, the width of the transition region of the epitaxial silicon wafer can be accurately measured, and thus a basis can be provided for evaluating the quality of the epitaxial silicon wafer.
[0058] An embodiment of the present invention further provides a measuring device for the width of the transition region of an epitaxial silicon wafer, as Figure 5 shown, including:
[0059] A measuring module 21, configured to obtain resistivity data at different depths of an epitaxial silicon wafer, and generate a resistivity curve based on the resistivity data, where the abscissa of the resistivity curve is the depth of the epitaxial silicon wafer, and the ordinate is the corresponding resistivity;
[0060] A first calculation module 22, configured to determine the slope of each position point on the resistivity curve, and determine the tangent at the target position point with the maximum slope;
[0061] A second calculation module 23, configured to select the resistivity curve corresponding to the first preset depth range, generate a first straight line based on the resistivity curve of the first preset depth range, select the resistivity curve corresponding to the second preset depth range, and generate a second straight line based on the resistivity curve of the second preset depth range, where the depths of the first preset depth range are all less than the depth of the target position point, and the depths of the second preset depth range are all greater than the depth of the target position point;
[0062] A determination module 24, configured to determine the first intersection point of the tangent and the first straight line and the second intersection point of the tangent and the second straight line;
[0063] A third calculation module 25, configured to subtract the abscissas of the first intersection point and the second intersection point to obtain the thickness of the epitaxial layer of the epitaxial silicon wafer.
[0064] In some embodiments, the second calculation module 23 is specifically configured to select a plurality of position points on the resistivity curve of the first preset depth range; fit the first straight line according to the resistivity data of the plurality of position points, and the linear equation corresponding to the first straight line is y = a 1 *x + b 1 , where a 1and b 1 are constants.
[0065] In some embodiments, the second calculation module 23 is specifically configured to select a plurality of position points on the resistivity curve within the second preset depth range; calculate the average resistivity b of the plurality of position points 3 , to obtain the second straight line, and the straight line equation corresponding to the second straight line is y = b 3 .
[0066] Please refer to Figure 6 , an embodiment of the present invention further provides an electronic device 30, including a processor 31, a memory 32, and a computer program stored on the memory 32 and executable on the processor 31. When the computer program is executed by the processor 31, it implements each process of the above-mentioned embodiment of the method for measuring the width of the epitaxial silicon wafer transition region, and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.
[0067] An embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements each process of the above-mentioned embodiment of the method for measuring the width of the epitaxial silicon wafer transition region, and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.
[0068] Among them, the computer-readable storage medium includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. The information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic disk storage or other magnetic storage for the to-be-detected terminal device or any other non-transmission medium that can be used to store information accessible by the to-be-detected terminal device. As defined herein, computer-readable storage media do not include transitory computer-readable media, such as modulated data signals and carrier waves.
[0069] An embodiment of the present application further provides a computer program product, including computer instructions, which when executed by a processor, implement the above Figure 1 shown in the method embodiment of each process, and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.
[0070] It should be noted that in this document, the term "including", "comprising", or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or device that includes a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article, or device that includes such element.
[0071] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described example methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disc) and includes several instructions for causing a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of the present invention.
[0072] In the method embodiments of the present disclosure, the sequence numbers of the respective steps cannot be used to limit the order of the steps. For those of ordinary skill in the art, without creative efforts, changes in the order of the steps are also within the protection scope of the present disclosure.
[0073] It should be noted that the various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the method embodiments, since they are basically similar to the product embodiments, they are described relatively simply, and the relevant parts can be referred to the description of the product embodiments.
[0074] The above is the preferred implementation of the present disclosure. It should be pointed out that for those of ordinary skill in the art, without departing from the principle described in the present disclosure, several improvements and refinements can be made, and these improvements and refinements should also be regarded as within the protection scope of the present disclosure.
Claims
1. A method for measuring the width of a transition zone of an epitaxial silicon wafer, characterized in that: include: Obtaining resistivity data of different depths of the epitaxial silicon wafer, and generating a resistivity curve according to the resistivity data, wherein the abscissa of the resistivity curve is the depth of the epitaxial silicon wafer, and the ordinate is the corresponding resistivity; Determine the slope of each position point on the resistivity curve, and determine the tangent line at the target position point with the largest slope; The resistivity curve corresponding to a first preset depth range is selected, and a first straight line is generated according to the resistivity curve of the first preset depth range; the resistivity curve corresponding to a second preset depth range is selected, and a second straight line is generated according to the resistivity curve of the second preset depth range, wherein the depth of the first preset depth range is less than the depth of the target location point, and the depth of the second preset depth range is greater than the depth of the target location point; Determine a first intersection point of the tangent line with the first straight line and a second intersection point of the tangent line with the second straight line; The thickness of the epitaxial layer of the epitaxial silicon wafer is obtained by subtracting the horizontal coordinates of the first intersection point and the second intersection point.
2. The method according to claim 1, characterized in that: The maximum depth of the first preset depth range is 75% of the depth of the epitaxial layer of the epitaxial silicon wafer, and the minimum depth of the first preset depth range is 25% of the depth of the epitaxial layer of the epitaxial silicon wafer.
3. The method according to claim 1, characterized in that: The second preset depth range is 6.5-7.5 microns.
4. The method according to claim 1 or 2, characterized in that: The generating a first straight line according to the resistivity curve of the first preset depth range comprises: Selecting a plurality of position points on the resistivity curve within the first preset depth range; The first straight line is obtained by fitting the resistivity data of the multiple position points, and the linear equation corresponding to the first straight line is y=a1*x+b1, wherein a1 and b1 are constants.
5. The method according to claim 1 or 3, characterized in that: The generating a second straight line according to the resistivity curve of the second preset depth range comprises: Selecting a plurality of position points on the resistivity curve within the second preset depth range; The average resistivity b3 of the plurality of position points is calculated to obtain the second straight line, and the linear equation corresponding to the second straight line is y=b3.
6. A device for measuring the width of transition zone of epitaxial silicon wafer, characterized in that: include: A measurement module, used to obtain resistivity data of different depths of the epitaxial silicon wafer, and generate a resistivity curve according to the resistivity data, wherein the abscissa of the resistivity curve is the depth of the epitaxial silicon wafer, and the ordinate is the corresponding resistivity; A first calculation module is used to determine the slope of each position point on the resistivity curve and determine the tangent line at the target position point with the largest slope; a second calculation module, configured to select the resistivity curve corresponding to a first preset depth range, generate a first straight line according to the resistivity curve of the first preset depth range, select the resistivity curve corresponding to a second preset depth range, generate a second straight line according to the resistivity curve of the second preset depth range, wherein the depth of the first preset depth range is less than the depth of the target location point, and the depth of the second preset depth range is greater than the depth of the target location point; A determination module, used to determine a first intersection point of the tangent line with the first straight line and a second intersection point of the tangent line with the second straight line; The third calculation module is used to obtain the thickness of the epitaxial layer of the epitaxial silicon wafer by subtracting the horizontal coordinates of the first intersection point and the second intersection point.
7. The device according to claim 6, characterized in that The second calculation module is specifically used to select multiple position points on the resistivity curve of the first preset depth range; the first straight line is fitted according to the resistivity data of the multiple position points, and the linear equation corresponding to the first straight line is y=a1*x+b1, where a1 and b1 are constants.
8. The device according to claim 6, characterized in that The second calculation module is specifically used to select multiple position points on the resistivity curve within the second preset depth range; calculate the average resistivity b3 of the multiple position points to obtain the second straight line, and the linear equation corresponding to the second straight line is y=b3.
9. An electronic device, characterized in that: include: A processor, a memory, and a program stored in the memory and executable on the processor, wherein when the program is executed by the processor, the steps of the method for measuring the width of the transition zone of an epitaxial silicon wafer as claimed in any one of claims 1 to 5 are implemented.
10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method for measuring the width of the transition zone of an epitaxial silicon wafer according to any one of claims 1 to 5 are implemented.