Preparation Method, Grinding Device and Detection Method of SRP Sample

Abstract

The present invention provides a method for preparing an SRP sample, a grinding device and a detection method, which relate to the technical field of semiconductor preparation. When preparing the SRP sample, first, a plurality of initial SRP samples of the same type are selected; then, the area of the SRP sample to be prepared is determined according to the preset grinding wafer specifications, and the splicing scheme of the initial SRP samples is determined based on the area of the SRP sample; then, the initial SRP samples are fixed on the silicon wafer substrate according to the splicing scheme, and a cover glass is covered on the initial SRP samples to obtain an intermediate SRP sample; finally, the intermediate SRP sample is placed in a grinding device that meets the preset grinding wafer specifications for grinding to obtain an SRP sample that meets the preset grinding wafer specifications. When dealing with small-sized SRP samples, this method uses samples of the same type for splicing to complete the preparation of the SRP sample, increases the sample preparation area of the SRP sample, enables the spliced SRP sample to have a sufficient needle-down distance, and improves the detection effect.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular, to a method for preparing an SRP sample, a grinding device, and a detection method. Background Art

[0002] SRP (Spreading resistance profile) testing is a method for testing electrical parameters such as diffusion resistance, resistivity, and carrier concentration distribution of semiconductor materials with high resolution, and is widely used in measuring resistivity and doping concentration. SRP testing obtains data through contact measurement of two probes on the inclined cross-section of a sample, and can quickly obtain curves of carrier concentration, resistivity, and electrically active impurity density with depth distribution.

[0003] With the improvement of semiconductor technology, the integration degree of SRP samples is also getting higher and higher. In small-area SRP analysis, due to the inability to grind, the measurable area of the sample is small, resulting in limited needle insertion distance and poor detection effect. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for preparing an SRP sample, a grinding device, and a detection method. For small-sized SRP samples, splicing is performed using samples of the same type to increase the sample preparation area of the SRP sample, so that the spliced SRP sample has sufficient needle insertion distance and improves the detection effect.

[0005] In the first aspect, an embodiment of the present invention provides a method for preparing an SRP sample, the method comprising:

[0006] Selecting a plurality of initial SRP samples of the same type; wherein, the initial SRP sample is in a loop structure;

[0007] Determining the SRP sample area to be prepared according to a preset grinding sheet specification, and determining the splicing scheme of the initial SRP samples according to the SRP sample area;

[0008] Fixing the initial SRP samples on a silicon wafer substrate according to the splicing scheme, and covering a cover glass on the initial SRP samples to obtain an intermediate SRP sample;

[0009] Placing the intermediate SRP sample in a grinding device that meets the preset grinding sheet specification, and grinding the intermediate SRP sample according to the time and rotation speed corresponding to the preset grinding sheet specification to obtain an SRP sample that meets the preset grinding sheet specification.

[0010] In some embodiments, the step of determining the measurement area of the SRP sample to be prepared according to a preset grinding sheet specification and determining the splicing scheme of the initial SRP samples according to the SRP sample measurement area includes:

[0011] Obtain the parameters included in the preset grinding disc specifications; wherein, the parameters at least include: test depth, number of needle points, needle pitch, and grinding angle;

[0012] Calculate the SRP sample area to be prepared according to the parameters;

[0013] Determine the number of initial SRP samples by using the ratio of the area of the SRP sample area to the area of the initial SRP sample, and determine the splicing scheme according to the number of initial SRP samples.

[0014] In some embodiments, fixing the initial SRP samples on the silicon wafer substrate according to the splicing scheme includes:

[0015] Determine the placement order of the initial SRP samples and the placement area of the silicon wafer substrate according to the splicing scheme;

[0016] Apply AB glue in the placement area of the silicon wafer substrate and place the initial SRP samples in sequence according to the placement order. After the AB glue solidifies, fix the initial SRP samples on the silicon wafer substrate.

[0017] In some embodiments, applying AB glue in the placement area of the silicon wafer substrate and placing the initial SRP samples in sequence according to the placement order includes:

[0018] Use the dispensing method to dot the AB glue in the placement area of the silicon wafer substrate;

[0019] Place the initial SRP samples side by side according to the placement order.

[0020] In some embodiments, fixing the initial SRP samples on the silicon wafer substrate after the AB glue solidifies includes:

[0021] Determine the pasting time of the initial SRP samples according to the amount of AB glue used; wherein, the pasting time is the time when the initial SRP samples can be fixed on the silicon wafer substrate under the current amount of AB glue used;

[0022] When the initial SRP samples reach the pasting time, use a heater to heat the initial SRP samples to make the AB glue completely solidify.

[0023] In some embodiments, the step of covering the initial SRP samples with a cover glass to obtain an intermediate SRP sample includes:

[0024] Apply AB glue on the surface of the initial SRP samples that have been fixed on the silicon wafer substrate;

[0025] Select a cover glass with the same size as the silicon wafer substrate and cover it on the surface of the initial SRP samples;

[0026] After the AB glue solidifies, obtain an intermediate SRP sample.

[0027] In some embodiments, after covering the surface of the initial SRP sample with a cover glass having the same size as the silicon wafer substrate, the following steps are further included:

[0028] Adjust the position of the cover glass so that it completely covers the surface of the initial SRP sample;

[0029] Use a heater to heat the initial SRP sample to completely solidify the AB glue.

[0030] In some embodiments, the area of the middle region in the loop structure of the initial SRP sample is 100 um × 100 um; the area of the initial SRP sample is 300 um × 300 um; the area of the silicon wafer substrate is 3 mm × 5 mm; and the area of the cover glass is 3 mm × 5 mm.

[0031] In a second aspect, an embodiment of the present invention provides a grinding device for an SRP sample, which is used to implement the method for preparing an SRP sample mentioned in the first aspect; the device includes: a sample grinding table, a fixing bracket, and a grinding machine;

[0032] Among them, the sample grinding table is used to place the SRP sample, and the sample grinding table includes multiple different grinding angles; the fixing bracket is arranged in the sample placement area of the sample grinding table and is used to fix the SRP sample; the grinding machine is used to grind the SRP sample.

[0033] In a third aspect, an embodiment of the present invention provides a detection method for an SRP sample, which is used to detect the doping concentration of the four sides of the SRP sample. The method includes:

[0034] Determine the maximum measurable area of the SRP according to the preset wafer grinding specification;

[0035] Select multiple initial SRP samples of the same type according to the maximum measurable area of the SRP, and use the method for preparing an SRP sample mentioned in the first aspect to obtain an SRP sample that meets the preset wafer grinding specification;

[0036] Perform SRP detection on the prepared SRP sample to obtain the doping concentration data of the SRP sample.

[0037] The embodiments of the present invention bring the following beneficial effects: The embodiments of the present invention provide a preparation method of an SRP sample, a grinding device, and a detection method. In the process of preparing the SRP sample, first, a plurality of initial SRP samples of the same type are selected; wherein, the initial SRP sample is in a loop structure; then, the area of the SRP sample to be prepared is determined according to the preset grinding sheet specification, and the splicing scheme of the initial SRP samples is determined according to the area of the SRP sample; then, the initial SRP samples are fixed on the silicon wafer substrate according to the splicing scheme, and a cover glass is covered on the initial SRP samples to obtain an intermediate SRP sample; finally, the intermediate SRP sample is placed in a grinding device that meets the preset grinding sheet specification, and the intermediate SRP sample is ground according to the time and rotation speed corresponding to the preset grinding sheet specification to obtain an SRP sample that meets the preset grinding sheet specification. When aiming at small-sized SRP samples, this method uses samples of the same category for splicing to complete the preparation of the SRP sample, increases the sample preparation area of the SRP sample, enables the spliced SRP sample to have a sufficient needle-down distance, and improves the detection effect.

[0038] Other features and advantages of the present invention will be described in the following description, and in part, will be obvious from the description, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are realized and obtained by the specific structures particularly pointed out in the description, the claims, and the drawings.

[0039] To make the above objectives, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given, and in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings

[0040] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0041] Figure 1 It is a flowchart of a preparation method of an SRP sample provided by an embodiment of the present invention;

[0042] Figure 2 It is a flowchart of step S102 in a preparation method of an SRP sample provided by an embodiment of the present invention;

[0043] Figure 3 It is a flowchart of fixing an initial SRP sample on a silicon wafer substrate according to a splicing scheme in a preparation method of an SRP sample provided by an embodiment of the present invention;

[0044] Figure 4In the method for preparing an SRP sample provided by an embodiment of the present invention, it is a flowchart of the process of applying AB glue in the placement area of the silicon wafer substrate and sequentially placing the initial SRP samples in the placement order;

[0045] Figure 5 In the method for preparing an SRP sample provided by an embodiment of the present invention, it is a flowchart of the process of fixing the initial SRP sample on the silicon wafer substrate after the AB glue solidifies;

[0046] Figure 6 In the method for preparing an SRP sample provided by an embodiment of the present invention, it is the process of covering the initial SRP sample with a cover glass to obtain an intermediate SRP sample;

[0047] Figure 7 It is a schematic structural diagram of the intermediate SRP sample obtained in the method for preparing an SRP sample provided by an embodiment of the present invention;

[0048] Figure 8 In the method for preparing an SRP sample provided by an embodiment of the present invention, it is a flowchart of the method after covering the surface of the initial SRP sample with a cover glass having the same size as the silicon wafer substrate;

[0049] Figure 9 It is a schematic structural diagram of a grinding device for an SRP sample provided by an embodiment of the present invention;

[0050] Figure 10 It is a schematic diagram of the grinding effect of a grinding device for an SRP sample provided by an embodiment of the present invention;

[0051] Figure 11 It is a flowchart of a detection method for an SRP sample provided by an embodiment of the present invention;

[0052] Figure 12 It is a schematic structural diagram of an initial SRP sample provided by an embodiment of the present invention.

[0053] Icon:

[0054] 910 - Grinding table; 920 - Fixed bracket; 930 - Grinder. Detailed implementation manners

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0056] SRP (Spreading resistance profile) test is a method for testing electrical parameters such as spreading resistance, resistivity, and carrier concentration distribution of semiconductor materials with high resolution. This method first measures the spreading resistance of a series of point contacts, and then uses a calibration curve to determine the resistivity of the sample to be measured near the probe contact point, and further converts it into the carrier concentration corresponding to a series of test points. In order to improve the spatial resolution and according to different target measurement depths, the sample cross-section direction can be ground into a series of angles. After grinding the silicon wafer at an angle, the resistivity change in the depth direction of resolution can be measured. SRP test can measure the spatial distribution of carrier concentration in the epitaxial, diffusion, and implantation processes of semiconductors such as Si, InP, GaAs, and SiC, and has become one of the more important test means in semiconductor material preparation and process production.

[0057] With the improvement of semiconductor technology, the integration of SRP samples is also getting higher and higher. When analyzing small-area SRP samples, due to the inability to grind, the measurable area of the sample is small, resulting in limited needle-down distance and poor detection effect.

[0058] To solve the above problems, the present invention proposes a preparation method, grinding device, and detection method for SRP samples. When dealing with small-sized SRP samples, samples of the same type can be used for splicing to complete the preparation of SRP samples, increasing the sample preparation area of SRP samples, enabling the spliced SRP samples to have sufficient needle-down distance, and improving the detection effect.

[0059] For the convenience of understanding this embodiment, first, a preparation method for an SRP sample disclosed in the embodiment of the present invention will be introduced in detail. Specifically, the flowchart of this method is as Figure 1 shown, including the following steps:

[0060] Step S101, select multiple initial SRP samples of the same type; among them, the initial SRP samples are in a loop structure.

[0061] The initial SRP samples are small-sized loop-structured samples. During the selection process, samples of the same type and similar sizes should be selected as much as possible to facilitate splicing. The initial SRP samples in a loop structure include an intermediate region and a boundary region, and the intermediate region or the boundary region can be measured according to the test requirements, such as measuring the doping concentration, carrier concentration, resistivity, etc. in the boundary region. The specific appearance of the initial SRP samples in a loop structure is as Figure 12As shown in the figure, when measuring the sample with a loop structure, the doping concentrations on the four sides of the middle region are generally measured, specifically, the doping concentrations in the boundary regions. For the initial SRP sample in the shape of a square, it can be divided according to the standard nine-square grid. The small square in the middle is the middle region, and the surrounding regions are the boundary regions. For example, the area of the middle region in the loop structure of the initial SRP sample is 100um×100um; it together with 8 identical regions around the middle region forms the boundary region, and the total area of the initial SRP sample at this time is 300um×300um.

[0062] Step S102: Determine the SRP sample area to be prepared according to the preset lapping specification, and determine the splicing scheme of the initial SRP sample based on the SRP sample area.

[0063] The lapping specifications mainly include parameters such as the test depth, lapping angle, stitch pitch, and number of stitch points. When the lapping angle is fixed, there is an inverse relationship between the test depth and the stitch pitch, that is, the larger the test depth, the larger the stitch pitch; the smaller the test depth, the smaller the stitch pitch. When the stitch pitch is fixed, there is a direct relationship between the test depth and the lapping angle, that is, the larger the test depth, the larger the lapping angle; the smaller the test depth, the smaller the lapping angle. For example: the lapping specification is: a lapping sample holder with a stitch pitch of 2.5um, 50 stitch points, a test depth of 50nm, and a use angle of 1°9'; similarly, the lapping specification can also be: a lapping sample holder with a stitch pitch of 5um, 50 stitch points, a test depth of 0.1um, and a use angle of 1°9'. One of the core parameters of the lapping specification is the test depth. The corresponding lapping angle can be determined through the test depth, and the measurable area of the sample can be calculated by combining the stitch pitch and the stitch points.

[0064] Taking the above lapping specifications as an example, when the lapping specification is a lapping sample holder with a stitch pitch of 2.5um, 50 stitch points, a test depth of 50nm, and a use angle of 1°9', the measurable area of the sample needs to be at least 125um×125um; when the lapping specification is a lapping sample holder with a stitch pitch of 5um, 50 stitch points, a test depth of 0.1um, and a use angle of 1°9', the measurable area of the sample needs to be at least 250um×250um. Under the condition that the measurable area of the sample needs to be at least 125um×125um, if the measurable range of the SRP sample is only 100um×100um, accurate measurement cannot be achieved, and the initial SRP sample needs to be spliced under the constraint of the measurable area of 125um×125um to determine the splicing scheme.

[0065] The splicing scheme mainly involves the splicing direction. When two initial SRP samples can meet the measurable area corresponding to the grinding specification, the different initial SRP samples can be spliced according to the same side length; when more than two initial SRP samples are needed to meet the measurable area corresponding to the grinding specification, the arrangement direction of these SRP samples needs to be considered, such as the "one" character arrangement, the "L" character arrangement, etc. The splicing process is also arranged according to the same side length.

[0066] Step S103, fix the initial SRP sample on the silicon wafer substrate according to the splicing scheme, and cover the cover glass on the initial SRP sample to obtain the intermediate SRP sample.

[0067] After the splicing scheme is determined, place these SRP samples on the silicon wafer substrate in sequence and position according to the splicing scheme, and fix them with glue. Generally speaking, when using glue for fixation, non-conductive glue needs to be used to prevent interference during detection.

[0068] After multiple initial SRP samples are fixed on the silicon wafer substrate, use a cover glass to cover the upper layer of the initial SRP sample for protection, and then obtain the intermediate SRP sample. The intermediate SRP sample at this time is a three-layer structure, which is the cover glass, the initial SRP sample, and the silicon wafer substrate from top to bottom. Different from the traditional SRP sample, the intermediate layer at this time contains multiple initial SRP samples. These initial SRP samples have similar sizes and are of the same type. After splicing, the measurable range can be expanded to meet the final measurement requirements.

[0069] Step S104, place the intermediate SRP sample in a grinding device that meets the preset grinding specification, and grind the intermediate SRP sample according to the time and rotation speed corresponding to the preset grinding specification to obtain an SRP sample that meets the preset grinding specification.

[0070] After the intermediate SRP sample is obtained, it needs to be ground according to the angle corresponding to the grinding specification. The grinding process is realized by a grinding device. The grinding device at least includes a sample grinding table, a fixing bracket, and a grinding machine. Specifically, select a sample grinding table with an appropriate angle according to the requirement of the test depth, then place the intermediate SRP sample in the sample grinding table, fix it with a fixing bracket and then use a grinding machine for grinding, and finally obtain an SRP sample that can meet the measurable area under the grinding specification.

[0071] It can be seen from the SRP sample preparation method provided in the above embodiments that when the method is applied to small-specification SRP samples, samples of the same type can be used for splicing to complete the preparation of SRP samples, increasing the sample preparation area of the SRP samples, making the spliced SRP samples have sufficient needle-down distance, and improving the detection effect.

[0072] In some embodiments, step S102 of determining the measurement area of the SRP sample to be prepared according to the preset abrasive disc specifications and determining the splicing scheme of the initial SRP sample based on the measurement area of the SRP sample is as follows Figure 2 shown and includes:

[0073] Step S201, obtaining the parameters included in the preset abrasive disc specifications; wherein, the parameters at least include: test depth, number of needle points, needle pitch, and grinding angle.

[0074] For example, the parameters included in the abrasive disc specification are: needle pitch 2.5um, 50 needle points, test depth 50nm, and an abrasive disc sample holder with an angle of use of 1°9'. The area of the middle region in the loop structure of the initial SRP sample is 100um×100um; the area of the initial SRP sample is 300um×300um.

[0075] Step S202, calculating the area of the SRP sample area to be prepared according to the parameters.

[0076] Taking the test depth of 50nm as an example, according to the abrasive disc specification requirements of 1°9', when the needle pitch is 2.5um and there are 50 needle points, the measurable area of the sample is at least 125um×125um. Therefore, the area of the SRP sample area to be prepared is also at least 125um×125um, and the area of the prepared SRP sample area can also be increased according to specific circumstances.

[0077] Step S203, using the ratio of the area of the SRP sample area to the area of the initial SRP sample to determine the number of initial SRP samples, and determining the splicing scheme according to the number of initial SRP samples.

[0078] Since the area of the SRP sample area must be larger than the area of the initial SRP sample, this ratio must be greater than 1. When the ratio is greater than 1 and less than 2, it indicates that at least 2 initial SRP samples are required to meet the requirements; similarly, when the ratio is greater than 2 and less than 3, it indicates that at least 3 initial SRP samples are required to meet the requirements. After determining the number of initial SRP samples, determine the splicing order and splicing direction according to the SRP sample area to be prepared, and then obtain the splicing scheme.

[0079] Specifically, the area of the middle region in the loop structure of the initial SRP sample is 100 um × 100 um; the area of the initial SRP sample is 300 um × 300 um; when measuring the doping concentration of the edge region, the edge region needs to be considered. At this time, the edge region can be understood as 8 regions of 100 um × 100 um, which are located around the middle region respectively. Taking the test depth of 50 nm as an example, according to the grinding specification requirements of 1°9′, when the needle pitch is 2.5 um and the number of needle points is 50, the measurable area of the sample is at least 125 um × 125 um. Therefore, two initial SRP samples can be selected and spliced. After splicing, the edge regions of the initial SRP samples are connected to reach 200 um, meeting the side length requirement of 125 um in the measurable area.

[0080] In some embodiments, the initial SRP sample is fixed on the silicon wafer substrate according to the splicing scheme, such as Figure 3 shown, including:

[0081] Step S301, determine the placement order of the initial SRP sample and the placement area of the silicon wafer substrate according to the splicing scheme.

[0082] Taking the above parameters as an example, after determining the splicing scheme of using two initial SRP samples for splicing, a silicon wafer substrate with an area of 3 mm × 5 mm is selected, and the placement positions and placement order of these two initial SRP samples are determined on the silicon wafer substrate.

[0083] Step S302, apply AB glue in the placement area of the silicon wafer substrate and place the initial SRP samples in sequence according to the placement order. After the AB glue solidifies, the initial SRP samples are fixed on the silicon wafer substrate.

[0084] In the actual operation process, the AB glue can be applied in sequence according to the placement order, and then the initial SRP samples are placed in sequence according to the placement order. After the AB glue solidifies, the initial SRP samples can be fixed on the silicon wafer substrate.

[0085] In the actual operation process, the process of applying AB glue in the placement area of the silicon wafer substrate and placing the initial SRP samples in sequence according to the placement order, such as Figure 4 shown, including:

[0086] Step S41, use the dispensing method to dispense the AB glue in the placement area of the silicon wafer substrate.

[0087] Dispensing is to use a sharp object to dip a small amount of AB glue to achieve the layout of the glue. A toothpick or a thin needle can be used to dip the least amount of AB glue, and then the glue is dispensed in the placement area of the silicon wafer substrate. It should be noted that the dispensing process follows the least amount of dispensing. If the amount of the first dispensing is insufficient, multiple dispensings can be carried out, but the final amount of dispensing should be as little as possible to prevent too much glue from affecting the test accuracy.

[0088] Step S42, place the initial SRP samples side by side in the arranged order.

[0089] When using the splicing scheme of splicing two initial SRP samples, the two initial SRP samples can be pasted side by side in the arranged order, and finally the splicing of the samples is achieved after the glue solidifies.

[0090] In some embodiments, the process of fixing the initial SRP sample on the silicon wafer substrate after the AB glue solidifies, as Figure 5 shown, includes:

[0091] Step S51, determine the pasting time of the initial SRP sample according to the amount of AB glue used; wherein, the pasting time is the time when the initial SRP sample can be fixed on the silicon wafer substrate under the current amount of AB glue used.

[0092] In the actual operation process, the pasting time can be reduced by using a heater. Specifically, first determine the pasting time of the initial SRP sample according to the amount of AB glue used, and this pasting time is the time when the initial SRP sample can be fixed on the silicon wafer substrate under the current amount of AB glue used. After reaching this time, the AB glue is in a semi-solidified state, which can ensure that the initial SRP sample in the glue can be preliminarily fixed on the silicon wafer substrate, and at this time, the internal glue has not solidified yet.

[0093] Step S52, when the initial SRP sample reaches the pasting time, use a heater to heat the initial SRP sample to make the AB glue completely solidify.

[0094] During the heating process of the heater, try to use the low-temperature baking method as much as possible. For example, the baking temperature of the heater can be set to 80° and heated for 5 minutes, and finally the AB glue is completely solidified, reducing the solidification time.

[0095] In some embodiments, the process of covering the cover glass on the initial SRP sample to obtain the intermediate SRP sample, as Figure 6 shown, includes:

[0096] Step S601, apply AB glue on the surface of the initial SRP sample that has been fixed on the silicon wafer substrate.

[0097] At this time, the initial SRP sample has been fixed on the silicon wafer substrate, and then apply AB glue on the surface of the initial SRP sample, and the amount of glue can be appropriately increased to better paste the cover glass.

[0098] Step S602, select a cover glass with the same size as the silicon wafer substrate and cover it on the surface of the initial SRP sample.

[0099] Taking the above parameters as an example, in the splicing scheme using two initial SRP samples for splicing, the selected area of the silicon wafer substrate is 3 mm × 5 mm, so the area of the cover glass is also 3 mm × 5 mm. After covering the cover glass on the surface of the initial SRP sample, adjust the position of the cover glass to make it fit with the silicon wafer substrate. At this time, the cover glass completely covers the two initial SRP samples after splicing.

[0100] Step S603, wait for the AB glue to solidify to obtain the intermediate SRP sample.

[0101] In actual operation, tools such as tweezers can be used to press the cover glass tightly to squeeze out the bubbles in the glue, and then wait for the AB glue to solidify to obtain the intermediate SRP sample. Specifically, as Figure 7 shown, it can be seen from Figure 7 that the intermediate SRP sample at this time is a three-layer structure, from top to bottom are the cover glass, two initial SRP samples, and the silicon wafer substrate. Different from the traditional SRP sample, the intermediate layer at this time contains multiple initial SRP samples. These initial SRP samples are similar in size and are of the same type. After splicing, the measurable range can be expanded to meet the final measurement requirements.

[0102] In some embodiments, after covering the cover glass with the same size as the silicon wafer substrate on the surface of the initial SRP sample, as Figure 8 shown, it further includes:

[0103] Step S81, adjust the position of the cover glass so that it completely covers the surface of the initial SRP sample.

[0104] The process of adjusting the cover glass can be realized by using tools such as tweezers, and finally make the cover glass completely cover the surface of the initial SRP sample, and then use a heater to heat and bake it.

[0105] Step S82, use a heater to heat the initial SRP sample to make the AB glue completely solidify.

[0106] In the actual operation process, a heavy object can be applied on the initial SRP sample covered with the cover glass, which helps the pasting effect. Then use a heater to heat and bake. The heating temperature in this step is generally higher than the heating temperature during glue dispensing. For example, the baking temperature of the heater can be set to 120° and heated for 10 minutes continuously, and finally the AB glue is completely solidified, reducing the solidification time.

[0107] It can be seen from the SRP sample preparation method provided in the above embodiments that when this method is aimed at small-sized SRP samples, two samples of the same type can be spliced to complete the preparation of the SRP sample, increasing the sample preparation area of the SRP sample, making the spliced SRP sample have enough needle-down distance, and improving the detection effect.

[0108] An embodiment of the present invention provides a grinding device for SRP samples, which is used for the preparation method of SRP samples mentioned in the above embodiments; as Figure 9 shown, the device includes: a sample grinding table 910, a fixing bracket 920, and a grinding machine 930;

[0109] Among them, the sample grinding table 910 is used to place SRP samples, and the sample grinding table 910 includes multiple different grinding angles; the fixing bracket 920 is arranged in the sample placement area of the sample grinding table 910 for fixing SRP samples; the grinding machine 930 is used to grind SRP samples.

[0110] When selecting a sample grinding table with an angle of 1°9′ and using a splicing scheme of splicing two initial SRP samples according to the requirement of the above test depth of 50 nm, the SRP samples are fixed in the sample placement area by using a heater and wax, and are fixed by using the fixing bracket 920. The grinding machine 930 is coated with uniform diamond paste and lubricating oil, and starts grinding according to the set time and rotation speed.

[0111] The grinding effect is as Figure 10 shown. Specifically, the area of the middle region in the loop structure of the initial SRP sample is 100 um×100 um; the area of the initial SRP sample is 300 um×300 um; when measuring the doping concentration of the edge region, the edge region needs to be considered. At this time, the edge region can be understood as 8 regions of 100 um×100 um, which are located around the middle region respectively. Taking the test depth of 50 nm as an example, according to the grinding sheet specification requirements of 1°9′, when the needle pitch is 2.5 um and the number of needle points is 50, the measurable area of the sample is at least 125 um×125 um. Therefore, two initial SRP samples can be selected and spliced. After splicing, the edge regions of the initial SRP samples are connected to reach 200 um, meeting the side length requirement of 125 um in the measurable area.

[0112] An embodiment of the present invention provides a detection method for SRP samples, which is used to detect the doping concentration of the four sides of SRP samples, as Figure 11 shown, the method includes:

[0113] Step S1101, determine the maximum measurable area of SRP according to the preset grinding sheet specification.

[0114] The specifications of the grinding disc mainly include the test depth, grinding angle, needle pitch, and number of needle points. For example, the grinding disc specifications are as follows: a grinding disc sample holder with a needle pitch of 2.5 μm, 50 needle points, a test depth of 50 nm, and a use angle of 1°9'; similarly, the grinding disc specifications can also be a grinding disc sample holder with a needle pitch of 5 μm, 50 needle points, a test depth of 0.1 μm, and a use angle of 1°9'. One of the core parameters of the grinding disc specifications is the test depth. The corresponding grinding angle can be determined by the test depth, and the measurable area of the sample can be calculated by combining the needle pitch and the number of needle points.

[0115] Specifically, when the grinding disc specifications are a grinding disc sample holder with a needle pitch of 2.5 μm, 50 needle points, a test depth of 50 nm, and a use angle of 1°9', the measurable area of the sample needs to be at least 125 μm × 125 μm; when the grinding disc specifications are a grinding disc sample holder with a needle pitch of 5 μm, 50 needle points, a test depth of 0.1 μm, and a use angle of 1°9', the measurable area of the sample needs to be at least 250 μm × 250 μm. Under the condition that the measurable area of the sample needs to be at least 125 μm × 125 μm, if the measurable range of the SRP sample is only 100 μm × 100 μm, accurate measurement cannot be achieved. Therefore, the initial SRP sample needs to be spliced according to the constraint of the measurable area of 125 μm × 125 μm to determine the splicing scheme.

[0116] Step S1102, select multiple initial SRP samples of the same type according to the maximum measurable area of the SRP, and obtain SRP samples that meet the preset grinding disc specifications by using the preparation method of the SRP samples mentioned in the above embodiments.

[0117] The SRP samples obtained in this step are spliced using multiple initial SRP samples of the same type, thereby increasing the sample preparation area of the SRP samples, making the spliced SRP samples have sufficient needle insertion distance, and improving the detection effect.

[0118] Specifically, the area of the middle region in the loop structure of the initial SRP sample is 100 μm × 100 μm; the area of the initial SRP sample is 300 μm × 300 μm. When measuring the doping concentration of the edge region, the edge region needs to be considered. At this time, the edge region can be understood as 8 regions of 100 μm × 100 μm, which are located around the middle region respectively. Taking the test depth of 50 nm as an example, according to the grinding disc specifications of 1°9', when the needle pitch is 2.5 μm and the number of needle points is 50, the measurable area of the sample is at least 125 μm × 125 μm. Therefore, two initial SRP samples can be selected and spliced. After splicing, the edge regions of the initial SRP samples are connected to reach 200 μm, meeting the side length requirement of 125 μm in the measurable area.

[0119] Step S1103: Perform SRP detection on the prepared SRP sample to obtain the doping concentration data of the SRP sample.

[0120] Detection data is obtained through contact measurement by two probes on the sample's inclined cross-section, and finally, the distribution curve of the doping concentration data of the SRP sample with depth is obtained.

[0121] The preparation method of the SRP sample provided in the embodiments of the present invention has the same implementation principle and technical effects as the preparation method of the SRP sample mentioned in the foregoing embodiments. For the sake of brief description, for the parts not mentioned in the embodiment part, reference can be made to the corresponding content in the foregoing method embodiments.

[0122] In several embodiments provided in the present application, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical function division, and there can be other division methods in actual implementation. For another example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some communication interfaces, and the indirect couplings or communication connections of devices or units can be in electrical, mechanical, or other forms.

[0123] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0124] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0125] If a function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile computer-readable storage medium executable by a processor. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in various embodiments of the present invention. The aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs that can store program codes.

[0126] Finally, it should be noted that: The above embodiments are only specific implementation manners of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: Any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments or easily think of changes, or perform equivalent replacements for some of the technical features; and these modifications, changes, or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing an SRP sample, characterized in that, the method includes: selecting a plurality of initial SRP samples of the same type; wherein, the initial SRP sample is in a loop structure; determining the area of the SRP sample to be prepared according to a preset grinding specification, and determining the splicing scheme of the initial SRP samples according to the area of the SRP sample; fixing the initial SRP samples on a silicon wafer substrate according to the splicing scheme, and covering a cover glass on the initial SRP samples to obtain an intermediate SRP sample; placing the intermediate SRP sample in a grinding device that meets the preset grinding specification, and grinding the intermediate SRP sample according to the time and rotation speed corresponding to the preset grinding specification to obtain an SRP sample that meets the preset grinding specification; The step of determining the measurement area of the SRP sample to be prepared according to a preset grinding specification and determining the splicing scheme of the initial SRP samples according to the measurement area of the SRP sample includes: obtaining the parameters included in the preset grinding specification; wherein, the parameters at least include: test depth, number of needle points, needle pitch and grinding angle; calculating the area of the SRP sample to be prepared according to the parameters; using the ratio of the area of the SRP sample area to the area of the initial SRP sample to determine the number of the initial SRP samples, and determining the splicing scheme according to the number of the initial SRP samples.

2. The method for preparing an SRP sample according to claim 1, characterized in that, fixing the initial SRP samples on a silicon wafer substrate according to the splicing scheme includes: determining the placement order of the initial SRP samples and the placement area of the silicon wafer substrate according to the splicing scheme; coating AB glue in the placement area of the silicon wafer substrate and sequentially placing the initial SRP samples according to the placement order, and fixing the initial SRP samples on the silicon wafer substrate after the AB glue solidifies.

3. The method for preparing an SRP sample according to claim 2, characterized in that, coating AB glue in the placement area of the silicon wafer substrate and sequentially placing the initial SRP samples according to the placement order includes: using a dispensing method to apply the AB glue in the placement area of the silicon wafer substrate; placing the initial SRP samples side by side according to the placement order.

4. The method for preparing an SRP sample according to claim 3, characterized in that, fixing the initial SRP samples on the silicon wafer substrate after the AB glue solidifies includes: determining the pasting time of the initial SRP samples according to the amount of the AB glue used; wherein, the pasting time is the time when the initial SRP samples can be fixed on the silicon wafer substrate under the current amount of the AB glue used; when the initial SRP samples reach the pasting time, heating the initial SRP samples with a heater to make the AB glue completely solidify.

5. The method for preparing an SRP sample according to claim 1, characterized in that, the step of covering a cover glass on the initial SRP samples to obtain an intermediate SRP sample includes: Apply AB glue on the surface of the initial SRP sample fixed on the silicon wafer substrate; Select a cover glass with the same size as the silicon wafer substrate and cover it on the surface of the initial SRP sample; After the AB glue solidifies, obtain the intermediate SRP sample.

6. The method for preparing an SRP sample according to claim 5, wherein, after selecting a cover glass with the same size as the silicon wafer substrate and covering it on the surface of the initial SRP sample, it further includes: Adjust the position of the cover glass so that it completely covers the surface of the initial SRP sample; Use a heater to heat the initial SRP sample to make the AB glue completely solidify.

7. The method for preparing an SRP sample according to claim 1, wherein, the area of the middle region in the loop structure of the initial SRP sample is 100um×100um; the area of the initial SRP sample is 300um×300um; the area of the silicon wafer substrate is 3mm×5mm; the area of the cover glass is 3mm×5mm.

8. A method for detecting an SRP sample, wherein, the method is used to detect the doping concentration of the four sides of the SRP sample, and the method includes: Determine the maximum measurable area of the SRP according to the preset wafer grinding specification; Select a plurality of initial SRP samples of the same type according to the maximum measurable area of the SRP, and use the method for preparing an SRP sample according to any one of claims 1 to 7 to obtain an SRP sample that meets the preset wafer grinding specification; Perform SRP detection on the prepared SRP sample to obtain the doping concentration data of the SRP sample.

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