Control wafer recovery method and control wafer in normal state

Abstract

The invention provides a control wafer recovery method and a normal state control wafer, and the method comprises the steps: carrying out the primary polishing of a monitoring surface of a to-be-recovered control wafer, obtaining an intermediate state control wafer of which the monitoring surface is a first roughness, and enabling the monitoring surface to be used for the detection of the doping concentration; the monitoring surface of the intermediate state control wafer is subjected to secondary polishing treatment, a normal state control wafer with the monitoring surface being second roughness is obtained, the first roughness is larger than the second roughness, and the resistivity of the monitoring surface of the normal state control wafer is larger than that of the monitoring surface of the intermediate state control wafer. Therefore, the monitoring surface of the control wafer to be recycled is sequentially subjected to primary polishing treatment and secondary polishing treatment to obtain the control wafer in a normal state, the resistivity of the monitoring surface of the control wafer is large, the roughness degree of the control wafer is small, and therefore the purpose of recycling and regenerating the used control wafer to be recycled is achieved, the production and manufacturing cost is greatly saved, and resource waste is avoided; and the maximization of resource utilization is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor manufacturing, and in particular relates to a control chip recovery method and a normal state control chip. Background Art

[0002] With the continuous development of modern science and technology, chips play an increasingly important role in our lives. In the production process of semiconductor chip products, doping technology is a very important process, which can locally change the conductivity and conductivity type of the wafer, and at the same time, doping can be used to manufacture a variety of device structures.

[0003] The commonly used doping technology is the ion implantation process. In order to accurately control the impurity concentration doped into the wafer, a control wafer is usually added during ion implantation or diffusion doping. The doping concentration is monitored by testing the resistivity or sheet resistance of the control wafer.

[0004] After ion implantation or diffusion doping, the resistivity of the wafer surface changes in traditional control chips, which will affect the accuracy of the next monitoring measurement. Therefore, the control chips will be discarded or downgraded to block chips after one use, which causes a huge waste of resources and increases manufacturing costs. Summary of the invention

[0005] The present application provides a control chip recovery method and a normal state control chip, aiming to solve the above-mentioned technical problems existing in the prior art.

[0006] To solve the above problems, the present application provides a control piece recovery method, which includes: performing a polishing process on the monitoring surface of the control piece to be recovered to obtain an intermediate state control piece whose monitoring surface is a first roughness, wherein the monitoring surface is used for doping concentration detection; performing a secondary polishing process on the monitoring surface of the intermediate state control piece to obtain a normal state control piece whose monitoring surface is a second roughness, wherein the first roughness is greater than the second roughness, and the resistivity of the monitoring surface of the normal state control piece is greater than the resistivity of the monitoring surface of the intermediate state control piece.

[0007] Among them, the step of polishing the monitoring surface of the control piece to be recovered to obtain an intermediate state control piece with a monitoring surface of the first roughness includes: determining the junction depth of the control piece to be recovered; polishing the monitoring surface of the control piece to be recovered according to a preset polishing depth to obtain the intermediate state control piece, wherein the preset polishing depth is greater than the junction depth.

[0008] Among them, after the step of polishing the monitored surface of the control piece to be recovered according to the preset polishing depth to obtain the intermediate state control piece, the control piece recovery method includes: obtaining the actual polishing depth of the intermediate state control piece; in response to the actual polishing depth being less than the preset polishing depth, repeatedly polishing the intermediate state control piece until the difference between the actual polishing depth of the intermediate state control piece and the preset polishing depth is within a preset range.

[0009] Among them, after the step of polishing the monitoring surface of the control piece to be recovered according to the preset polishing depth to obtain the intermediate state control piece, the control piece recovery method also includes: determining the control piece thickness at multiple points on the monitoring surface of the control piece to be recovered; in response to the difference between the multiple control piece thicknesses being greater than a first preset thickness threshold, repeatedly polishing the intermediate state control piece until the difference between the multiple control piece thicknesses is less than the first preset thickness threshold.

[0010] Among them, after the step of performing a secondary polishing treatment on the monitoring surface of the intermediate state control piece to obtain a normal state control piece with a monitoring surface of the second roughness, the control piece recovery method also includes: determining the resistivity of multiple points on the monitoring surface of the normal state control piece; in response to the resistivity of multiple points being within a preset resistivity range, determining that the normal state control piece is in a qualified state; in response to at least one of the resistivity of multiple points being outside the preset resistivity range, determining that the normal state control piece is in an unqualified state.

[0011] Among them, after the step of performing secondary polishing on the monitoring surface of the intermediate state control piece to obtain a normal state control piece with a monitoring surface of the second roughness, the control piece recovery method also includes: performing ion implantation on the monitoring surface of the normal state control piece to obtain a doped state control piece; determining the resistance values ​​of multiple points on the monitoring surface of the doped state control piece; determining the resistance uniformity value of the monitoring surface of the doped state control piece based on the multiple resistance values; and determining whether the normal state control piece is qualified based on the resistance uniformity value and a preset uniformity threshold.

[0012] Among them, the step of determining the resistance uniformity value of the monitoring surface of the doping state control piece based on the multiple resistance values ​​includes: calculating the average value of the multiple resistance values ​​and the difference between the maximum value and the minimum value of the multiple resistance values ​​to obtain the target difference; dividing the target difference by a preset multiple of the average value to obtain the resistance uniformity value.

[0013] Among them, before the step of performing a polishing treatment on the monitoring surface of the control piece to be recovered to obtain an intermediate state control piece with a monitoring surface of the first roughness, the control piece recovery method also includes: performing oxidative corrosion on the monitoring surface of the control piece to be recovered so that the thickness of the oxide layer on the monitoring surface of the control piece to be recovered is less than a second preset thickness threshold.

[0014] Wherein, after the step of performing a primary polishing treatment on the monitoring surface of the control piece to be recovered to obtain an intermediate state control piece whose monitoring surface has a first roughness, the control piece recovery method further includes: performing a primary cleaning treatment on the intermediate state control piece; and / or, after the step of performing a secondary polishing treatment on the monitoring surface of the intermediate state control piece to obtain a normal state control piece whose monitoring surface has a second roughness, the control piece recovery method includes: performing a secondary cleaning treatment on the normal state control piece.

[0015] In order to solve the above technical problems, another technical solution adopted by the present application is: to provide a normal state control sheet, wherein the normal state control sheet is obtained by processing the control sheet to be recycled using the control sheet recycling method as described above.

[0016] Different from the prior art, the control sheet recycling method in the present application includes: performing a polishing process on the monitoring surface of the control sheet to be recycled to obtain an intermediate state control sheet with a monitoring surface of the first roughness, wherein the monitoring surface is used for doping concentration detection; performing a secondary polishing process on the monitoring surface of the intermediate state control sheet to obtain a normal state control sheet with a monitoring surface of the second roughness, wherein the first roughness is greater than the second roughness, and the resistivity of the monitoring surface of the normal state control sheet is greater than the resistivity of the monitoring surface of the intermediate state control sheet. Through the above implementation, the monitoring surface of the control sheet to be recycled is polished once and twice in sequence to obtain a normal state control sheet with a larger resistivity and a smaller roughness on the monitoring surface, thereby achieving the purpose of recycling and regenerating the control sheet to be recycled after use, greatly saving production and manufacturing costs, avoiding waste of resources, and maximizing resource utilization. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic flow chart of an embodiment of the control chip recovery method provided by the present application;

[0019] Figure 2 yes Figure 1A schematic flow chart of an embodiment of step S101;

[0020] Figure 3 yes Figure 1 A schematic diagram of the first embodiment flow chart after step S102;

[0021] Figure 4 yes Figure 1 FIG. 1 is a flow chart of the second embodiment after step S102. DETAILED DESCRIPTION

[0022] The present application is further described in detail below in conjunction with the accompanying drawings and examples. It is particularly noted that the following examples are only used to illustrate the present application, but are not intended to limit the scope of the present application. Similarly, the following examples are only some embodiments of the present application rather than all embodiments, and all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present application.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "set", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or connected through an intermediate medium. For ordinary technicians in this field, the above-mentioned specific meanings belonging to this application can be connected according to specific circumstances.

[0025] With the continuous development of modern science and technology, chips play an increasingly important role in our lives. In the production process of semiconductor chip products, doping technology is a very important process, which can locally change the conductivity and conductivity type of the wafer, and at the same time, doping can be used to manufacture a variety of device structures.

[0026] The commonly used doping technology is the ion implantation process. In order to accurately control the impurity concentration doped into the wafer, a control wafer is usually added during ion implantation or diffusion doping. The doping concentration is monitored by testing the resistivity or sheet resistance of the control wafer.

[0027] After ion implantation or diffusion doping, the resistivity of the wafer surface changes in traditional control chips, which will affect the accuracy of the next monitoring measurement. Therefore, the control chips will be discarded or downgraded to block chips after one use, which causes a huge waste of resources and increases manufacturing costs.

[0028] In order to solve the technical problems existing in the related art, the present application provides a control chip recovery method, see Figure 1 , Figure 1 It is a flow chart of an embodiment of the control chip recovery method provided in the present application, specifically, it includes the following steps S101 to S102.

[0029] Step S101: performing a polishing process on the monitoring surface of the control wafer to be recovered to obtain an intermediate state control wafer with a monitoring surface of a first roughness, wherein the monitoring surface is used for doping concentration detection.

[0030] The control piece can be used to detect the doping concentration of semiconductors. For example, a specific control piece can be used for conventional doping concentration monitoring by measuring the resistance of the control piece surface after ion implantation or diffusion doping. The monitoring surface can be understood as the surface of the control piece used for doping concentration detection. The resistivity of the monitoring surface of the control piece used for doping ions in a normal state is usually 10-25Ω.cm, while the resistivity of the monitoring surface of the control piece after use is significantly lower than the resistivity of the control piece in a normal state. For example, the resistivity of the control piece after use can be 1-3Ω.cm, which will cause such control pieces to seriously affect the measurement accuracy due to their low resistivity and thus cannot be used again.

[0031] In this embodiment, the control piece to be recycled may include but is not limited to a used control piece or other types of control pieces with a low resistivity on the monitoring surface. The primary polishing process can be understood as a rough polishing process. During the rough polishing process, the thickness of the control piece to be recycled is focused on polishing away, thereby removing the portion of the control piece to be recycled that is doped with more impurities or has impurities, so as to obtain an intermediate state control piece. Since the monitoring surface of the control piece to be recycled is subjected to a rough polishing process, the first roughness of the monitoring surface of the intermediate state control piece finally obtained is relatively large. Among them, the primary polishing can be to polish the monitoring surface of the control piece to be recycled using a grinding wheel and a polishing liquid. The polishing liquid can be an alkaline solution, which reacts with the monitoring surface while the grinding wheel polishes it, and finally polishes away a specific thickness of the control piece to be recycled, thereby obtaining an intermediate state control piece.

[0032] Step S102: Perform secondary polishing on the monitoring surface of the intermediate state control piece to obtain a normal state control piece with a monitoring surface of the second roughness, wherein the first roughness is greater than the second roughness, and the resistivity of the monitoring surface of the normal state control piece is greater than the resistivity of the monitoring surface of the intermediate state control piece.

[0033] The normal state control wafer can be understood as a control wafer that can be used for doping concentration monitoring again. After a polishing process, the first roughness of the monitoring surface of the intermediate state control wafer is relatively large, which makes it difficult to use it for doping concentration detection to obtain a more accurate detection result. Therefore, the monitoring surface of the intermediate state control wafer can be polished twice to reduce the roughness of the monitoring surface of the intermediate state control wafer, so as to obtain a normal state control wafer. Specifically, the method of secondary polishing treatment may include but is not limited to using a polishing liquid and a grinding wheel machine to treat the monitoring surface of the intermediate state control wafer, wherein the composition ratio of the polishing liquid used in the secondary polishing process may be different from the composition ratio of the polishing liquid used in the first polishing process, so that the surface damage introduced during the first polishing process can be repaired during the secondary polishing process, and the monitoring surface after the secondary polishing process can restore the super-mirror state of the wafer surface, so that the monitoring surface of the normal state control wafer has no scratches and no polishing liquid residue.

[0034] It can be understood that the second roughness of the monitoring surface of the normal state control piece obtained after the second polishing is smaller than the first roughness, and the resistivity of the monitoring surface of the normal state control piece can meet the requirements of accurate measurement. For example, the resistivity of the monitoring surface of the normal state control piece is 25Ω.cm, which is within the range of 10-25Ω.cm and can be used for detection of semiconductor doping concentration, etc.

[0035] Through the above implementation mode, the monitoring surface of the control piece to be recycled is subjected to a primary polishing treatment and a secondary polishing treatment in sequence to obtain a normal state control piece with a larger resistivity and a smaller roughness on the monitoring surface, thereby achieving the purpose of recycling the control piece to be recycled after use, greatly saving the production cost, avoiding waste of resources, and realizing the maximum utilization of resources.

[0036] Furthermore, after the step of polishing the monitoring surface of the control wafer to be recovered to obtain an intermediate state control wafer with a monitoring surface of the first roughness (step S101), the control wafer recovery method includes: performing a cleaning process on the intermediate state control wafer. The intermediate state control wafer obtained after a polishing process is usually also subjected to a cleaning process, because there is a large amount of silicon slag on the surface of the wafer after a polishing process, and there may be polishing liquid residue. The specific cleaning process method is to use SC-1 liquid to clean the surface to remove particles, further perform QDR flushing and place it in a spin dryer for centrifugal drying, wherein the SC-1 liquid can be heated to 60-70 degrees Celsius to improve the cleaning effect of the SC-1 liquid.

[0037] And / or, after the step of performing a secondary polishing process on the monitoring surface of the intermediate state control wafer to obtain a normal state control wafer with a monitoring surface of the second roughness, the control wafer recovery method includes: performing a secondary cleaning process on the normal state control wafer. After the secondary polishing process on the intermediate state control wafer, the obtained normal state control wafer is usually also subjected to a secondary cleaning process, the purpose of which is also to remove particles on the wafer surface and avoid polishing liquid residue. The specific cleaning method can be the same as the primary cleaning process method, which will not be repeated here.

[0038] See also Figure 2 , Figure 2 yes Figure 1 A flowchart of an embodiment of step S101 is shown in FIG.

[0039] Step S201: Determine the junction depth of the control wafer to be recovered.

[0040] Since the impurities after doping will exist on the monitoring surface of the control wafer to be recovered, the deepest impurity can be understood as the junction depth. The junction depth usually depends on the process of diffusion and pushing the junction after impurity doping. The area below the junction depth is the undoped area, and its resistivity is basically consistent with the resistivity of the monitoring surface before doping. The junction depth can be obtained through the SRP extended resistance test, which is not specifically limited here.

[0041] Step S202: polishing the monitoring surface of the control wafer to be recovered once according to a preset polishing depth to obtain an intermediate state control wafer, wherein the preset polishing depth is greater than the knot depth.

[0042] The preset polishing depth can be determined based on the junction depth and actual conditions. It only needs to satisfy that the preset polishing depth is greater than the junction depth. For example, the preset polishing depth can be greater than the junction depth by more than 3μm. For example, when the determined junction depth is 12μm, the preset polishing depth can be 15-20μm. It can be understood that this can ensure that the impurity area introduced by ion implantation in the control piece to be recovered is completely removed, so that the resistivity of the monitoring surface of the control piece in the intermediate state is basically the same as the resistivity of the monitoring surface of the control piece in the normal state.

[0043] As shown in Table 1 below, it is a comparison table of the thickness of the control sheets to be recycled before and after polishing during one polishing process. It can be seen that the actual polishing depth of the six control sheets is greater than the maximum knot depth, meeting the preset polishing depth requirements. The thickness of the control sheet can be tested using a film thickness meter or an ellipsometer.

[0044]

[0045] Table 1: Thickness comparison table of the recycled control sheet before and after polishing

[0046] Further, after polishing the monitored surface of the control piece to be recovered according to the preset polishing depth to obtain the intermediate state control piece (step S202), the control piece recovery method includes: obtaining the actual polishing depth of the intermediate state control piece; in response to the actual polishing depth being less than the preset polishing depth, repeatedly polishing the intermediate state control piece until the difference between the actual polishing depth of the intermediate state control piece and the preset polishing depth is within a preset range.

[0047] After the intermediate state control piece is obtained through a polishing process, its polishing depth needs to be determined to ensure that the actual polishing depth is consistent with the preset polishing depth. If the actual polishing depth is insufficient, the control piece needs to be polished again until the actual polishing depth of the control piece meets the requirements. Exemplarily, the preset range may include but is not limited to 1-3μm. When the junction depth of the control piece to be recovered is determined to be 12μm, the preset polishing depth is 20μm, and after a polishing process is performed and the actual polishing depth is detected, it is determined that the actual polishing depth of the intermediate state control piece is 12μm, while the preset polishing depth is 20μm. The difference between the actual polishing depth and the preset polishing depth is 8μm, and the difference between the two is not within the preset range. At this time, the intermediate state control piece can be repeatedly polished, and after a polishing process is completed, the actual polishing depth is determined again, and the actual polishing depth is compared with the preset polishing depth again. When the difference between the actual polishing depth and the preset polishing depth is within the preset range, it can be determined that the actual polishing depth meets the requirements.

[0048] In some embodiments, after polishing the monitoring surface of the control sheet to be recovered according to a preset polishing depth to obtain an intermediate state control sheet (step S202), the control sheet recovery method includes: determining the control sheet thickness at multiple points on the monitoring surface of the control sheet to be recovered; in response to the difference between the multiple control sheet thicknesses being greater than a first preset thickness threshold, repeatedly polishing the intermediate state control sheet until the difference between the multiple control sheet thicknesses is less than the first preset thickness threshold.

[0049] The multiple points may include but are not limited to two points, three points, four points, etc. The first preset thickness threshold may be set according to the actual situation. For example, the first preset thickness threshold may include but is not limited to 2μm, 3μm, 4μm, etc. After the intermediate state control piece is obtained through a polishing process, its polished flatness needs to be determined to ensure that the flatness of the intermediate state control piece is sufficient, that is, when the thickness difference between the multiple points is less than the first preset thickness threshold, it can be determined that the flatness of the intermediate state control piece is sufficient; when the thickness difference between the multiple points is greater than the first preset thickness threshold, it can be determined that the flatness of the intermediate state control piece is insufficient. At this time, the control piece can be polished again until the actual polished flatness of the control piece meets the requirements. Exemplarily, the first preset thickness threshold is 3μm, and the thickness of the control sheet at multiple points is determined to be 600μm, 608μm, 605μm, and 610μm, respectively. Obviously, at this time, the difference between the thickness of the control sheet at multiple points is greater than the first preset thickness threshold. At this time, the intermediate state control sheet can be repeatedly polished, and after one polishing process is completed, it is determined again whether the difference between the thickness of the control sheet at multiple points is less than the first preset thickness threshold. When the difference between the thickness of the control sheet at multiple points is less than the first preset thickness threshold, it can be determined that the actual polished flatness meets the requirements.

[0050] See also Figure 3 , Figure 3 yes Figure 1 FIG. 1 is a flow chart of the first embodiment after step S102.

[0051] Step S301: Determine the resistivity of multiple points on the monitoring surface of the normal state control sheet.

[0052] The multiple points may include but are not limited to two points, three points, four points or five points, etc. The resistivity of the multiple points on the monitoring surface of the normal state control sheet can be detected according to actual conditions and is not limited here.

[0053] Step S302: In response to the resistivity of the plurality of points being within a preset resistivity range, determining that the normal state control sheet is in a qualified state.

[0054] The preset resistivity range may include but is not limited to 10-25Ω.cm. When the resistivities of multiple detected points are all within the preset resistivity range, it can be preliminarily determined that the normal state control piece meets the requirements of further testing, and then the normal state control piece can be determined to be qualified, and the normal state control piece can be directly used for subsequent doping concentration testing.

[0055] Step S303: In response to at least one of the resistivities of the plurality of points being outside a preset resistivity range, determining that the normal state control sheet is in an unqualified state.

[0056] When at least one of the resistivity of the multiple points detected is outside the preset resistivity range, it can be preliminarily determined that the normal state control piece does not meet the requirements of further testing, and then it can be determined that the normal state control piece is in an unqualified state, and further polishing of the normal state control piece can be considered to make the normal state control piece qualified. Exemplarily, the preset resistivity range may include but is not limited to 10-25Ω.cm, wherein one of the resistivity of the multiple points is 9Ω.cm, which is not within the preset resistivity range, and at this time it can be determined that the normal state control piece is in an unqualified state, as shown in Table 2 below:

[0057]

[0058] Table 2: Resistivity test results of the control sheet in normal state

[0059] As shown in Table 2, the resistivity test results of the control pieces in normal state obtained after the control pieces to be recycled are shown. A total of 6 control pieces to be recycled after processing were tested, and five points were tested on each control piece, all of which met the range of standard values, that is, the 6 control pieces in normal state can be defined as qualified.

[0060] See also Figure 4 , Figure 4 yes Figure 1 FIG. 1 is a flow chart of the second embodiment after step S102.

[0061] Step S401: performing ion implantation on the monitoring surface of the normal state control wafer to obtain the doped state control wafer.

[0062] After obtaining the normal state control wafer, in order to further determine whether the normal state control wafer obtained by the process flow is qualified, ion implantation can be performed on the monitoring surface of the normal state control wafer, that is, the normal state control wafer is doped to obtain the doped state control wafer after doping.

[0063] Step S402: determining the resistance values ​​of a plurality of points on the monitoring surface of the doping state control sheet.

[0064] The multiple points may be different points on the monitoring surface of the doping state control sheet, and may include but are not limited to two points, three points, four points, or five points, etc., and each point corresponds to a resistance value.

[0065] Step S403: determining the resistance uniformity value of the monitoring surface of the doping state control wafer according to the multiple resistance values.

[0066] The resistance value of the monitoring surface of the doping state control sheet can be obtained according to a specific calculation formula. For example, the resistance uniformity value of the monitoring surface of the doping state control sheet can be determined by calculating multiple resistance values ​​corresponding to multiple points.

[0067] Step S404: Determine whether the normal state control chip is qualified based on the resistance uniformity value and the preset uniformity threshold.

[0068] The preset uniformity threshold can be set according to the actual situation, and the resistance uniformity value and the preset uniformity threshold can be compared, so as to determine whether the normal state control chip is qualified according to the comparison result. Specifically, based on the resistance uniformity value and the preset uniformity threshold, the step of determining whether the normal state control chip is qualified may include: in response to the resistance uniformity value being less than the preset uniformity threshold, determining that the normal state control chip is in a qualified state; in response to the resistance uniformity value being greater than the preset uniformity threshold, determining that the normal state control chip is in an unqualified state. Please refer to the following Table 3:

[0069]

[0070] Table 3: Sheet resistance test results of new and normal wafers after ion implantation

[0071] In Table 3, the block resistance can be understood as the average value of multiple resistance values ​​at multiple points on the monitoring surface of multiple doping state control pieces, and the intra-piece U% can be understood as the resistance uniformity value corresponding to each control piece, and the preset uniformity threshold is 3%. It can be seen from Table 3 that the average block resistance values ​​of the 6 control pieces all meet the block resistance specification, and the intra-piece resistance uniformity values ​​are all less than the preset uniformity threshold, that is, less than 3%. It can be understood that by monitoring the doping concentration after ion implantation of the normal state control piece obtained after treatment and the new control piece, the monitoring effects of the two control pieces meet the requirements, which further verifies that the normal state control piece obtained by polishing and recovering the control piece to be recovered using the control piece recovery method of the above embodiment has basically the same performance as the new control piece.

[0072] Furthermore, the step of determining the resistance uniformity value of the monitoring surface of the doping state control sheet according to multiple resistance values ​​includes: calculating the average value of the multiple resistance values, and the difference between the maximum value and the minimum value of the multiple resistance values ​​to obtain a target difference; dividing the target difference by a preset multiple of the average value to obtain a resistance uniformity value. The preset multiple can be set according to actual conditions. For example, the preset multiple can be 2, or a value of 1.5, 2.5 or 3, etc. The resistance uniformity value can be determined by several resistance values ​​obtained by several tests through the above calculation method. It can be understood that the smaller the uniformity value, the smaller the difference in test values ​​between multiple points, the smaller the difference between the entire sheet, and the better the monitoring accuracy.

[0073] In some embodiments, before performing a polishing treatment on the monitoring surface of the control wafer to be recovered to obtain an intermediate state control wafer with a monitoring surface of a first roughness (step S101), the control wafer recovery method includes: performing oxidative corrosion on the monitoring surface of the control wafer to be recovered so that the thickness of the oxide layer on the monitoring surface of the control wafer to be recovered is less than a second preset thickness threshold.

[0074] Before the monitoring surface of the control piece to be recovered is subjected to a first polishing treatment, the oxide layer on the surface of the control piece to be recovered is also corroded so that the oxide layer thickness on its surface is less than the second preset thickness threshold. The oxide layer can be corroded with a diluted hydrofluoric acid solution (DHF), and the second preset thickness threshold can be set according to actual conditions. For example, the second thickness threshold can include but is not limited to 100 angstroms, 90 angstroms, etc. The reason for corroding the oxide layer on the surface of the control piece to be recovered is that the presence of an overly thick oxide layer on the monitoring surface of the control piece to be recovered will affect the amount of polishing removed in a single polishing, thereby affecting the polishing effect. Therefore, before a single polishing treatment, the oxide layer on the monitoring surface of the control piece to be recovered is first corroded to alleviate the effect of the oxide layer on the amount of polishing removed in a single polishing, thereby improving the polishing effect of a single polishing treatment.

[0075] To sum up, the monitoring surface of the control piece to be recycled is polished once and twice in sequence to obtain a normal state control piece with a larger resistivity and less roughness on the monitoring surface, thereby achieving the purpose of recycling the control piece to be recycled after use, greatly saving production costs, avoiding waste of resources, and maximizing resource utilization.

[0076] In order to solve the technical problems existing in the relevant embodiments, another technical solution adopted by the present application is: to provide a normal state control piece, and the normal state control piece is obtained by processing the control piece to be recovered using the control piece recovery method of any of the above embodiments.

[0077] Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A control sheet recovery method, characterized in that: The control piece recovery method comprises: Performing a polishing process on the monitoring surface of the control wafer to be recovered to obtain an intermediate state control wafer with a monitoring surface of a first roughness, wherein the monitoring surface is used for doping concentration detection; The monitoring surface of the intermediate state control piece is polished twice to obtain a normal state control piece with a monitoring surface of the second roughness, wherein the first roughness is greater than the second roughness, and the resistivity of the monitoring surface of the normal state control piece is greater than the resistivity of the monitoring surface of the intermediate state control piece.

2. The control piece recovery method according to claim 1, characterized in that: The step of performing a polishing process on the monitoring surface of the control piece to be recovered to obtain an intermediate state control piece with a monitoring surface of the first roughness comprises: Determining the junction depth of the control piece to be recovered; The monitoring surface of the control piece to be recovered is polished once according to a preset polishing depth to obtain the control piece in the intermediate state, wherein the preset polishing depth is greater than the junction depth.

3. The control piece recovery method according to claim 2, characterized in that: After the step of polishing the monitoring surface of the control piece to be recovered once according to the preset polishing depth to obtain the control piece in the intermediate state, the control piece recovery method includes: Obtaining the actual polishing depth of the control piece in the intermediate state; In response to the actual polishing depth being less than the preset polishing depth, the polishing process is repeatedly performed on the intermediate state control piece until the difference between the actual polishing depth and the preset polishing depth of the intermediate state control piece is within a preset range.

4. The control piece recovery method according to claim 2, characterized in that: After the step of polishing the monitoring surface of the control piece to be recovered once according to the preset polishing depth to obtain the control piece in the intermediate state, the control piece recovery method includes: Determining the thickness of the control sheet at multiple points on the monitoring surface of the control sheet to be recovered; In response to the difference between the thicknesses of the plurality of control sheets being greater than a first preset thickness threshold, the intermediate state control sheet is repeatedly polished until the difference between the thicknesses of the plurality of control sheets is less than the first preset thickness threshold.

5. The control piece recovery method according to claim 1, characterized in that: After the step of performing secondary polishing on the monitoring surface of the intermediate state control piece to obtain a normal state control piece having a monitoring surface of the second roughness, the control piece recovery method comprises: Determining the resistivity of a plurality of points on the monitoring surface of the normal state control sheet; In response to the resistivity of the plurality of points being within a preset resistivity range, determining that the normal state control sheet is in a qualified state; In response to at least one of the resistivities at the plurality of points being outside a preset resistivity range, the normal state control sheet is determined to be in an unqualified state.

6. The control piece recovery method according to claim 1, characterized in that: After the step of performing secondary polishing on the monitoring surface of the intermediate state control piece to obtain a normal state control piece having a monitoring surface of the second roughness, the control piece recovery method comprises: Performing ion implantation on the monitoring surface of the normal state control wafer to obtain a doped state control wafer; Determining the resistance values ​​of multiple points on the monitoring surface of the doping state control sheet; Determining a resistance uniformity value of a monitoring surface of the doping state control sheet according to the plurality of resistance values; Based on the resistance uniformity value and a preset uniformity threshold, it is determined whether the normal state control wafer is qualified.

7. The control piece recovery method according to claim 6, characterized in that: The step of determining the resistance uniformity value of the monitoring surface of the doping state control sheet according to the plurality of resistance values ​​comprises: Calculating an average value of the plurality of resistance values ​​and a difference between a maximum value and a minimum value among the plurality of resistance values ​​to obtain a target difference value; The target difference is divided by a preset multiple of the average value to obtain the resistance uniformity value.

8. The control chip recovery method according to claim 1, characterized in that: Before the step of performing a polishing treatment on the monitoring surface of the control piece to be recovered to obtain a control piece in an intermediate state with a monitoring surface of the first roughness, the control piece recovery method includes: The monitoring surface of the control piece to be recovered is subjected to oxidation corrosion so that the thickness of the oxide layer on the monitoring surface of the control piece to be recovered is less than a second preset thickness threshold.

9. The control piece recovery method according to claim 1, characterized in that: After the step of performing a polishing process on the monitoring surface of the control piece to be recovered to obtain a control piece in an intermediate state with a monitoring surface of the first roughness, the control piece recovery method comprises: Performing a cleaning process on the intermediate state control piece; And / or, after the step of performing a secondary polishing process on the monitoring surface of the intermediate state control piece to obtain a normal state control piece having a monitoring surface of the second roughness, the control piece recovery method comprises: The normal state control piece is subjected to a secondary cleaning process.

10. A normal state control film, characterized in that: The normal state control chip is obtained by processing the control chip to be recovered using the control chip recovery method according to any one of claims 1 to 9.

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