Process equipment and processing method of solar cell

Abstract

The invention discloses process equipment and a solar cell processing method, and belongs to the technical field of photovoltaic solar cells. The disclosed process equipment comprises a process chamber, a main machine table and a film thickness detection piece, the process chamber is used for processing a silicon wafer, the main machine table can adjust process parameters of the process chamber, the film thickness detection piece can detect the film thickness of a polycrystalline silicon layer of the silicon wafer, the film thickness detection piece is in communication connection with the main machine table, and the main machine table is used for detecting the film thickness of the polycrystalline silicon layer of the silicon wafer. And under the condition that the film thickness is larger than a first preset threshold value or smaller than a second preset threshold value, the main machine table adjusts the technological parameters. According to the scheme, the problems that the film thickness adjustment is not timely, the debugging effect is poor and the labor cost is high in the prior art can be solved.

Description

Technical Field

[0001] The present application belongs to the technical field of photovoltaic solar cells, and specifically relates to a process equipment and a method for processing solar cells. Background Art

[0002] With the rapid development of solar cells, people have higher and higher requirements for the battery performance of solar cells. Solar cells generally include TOPCon (Tunnel Oxide Passivated Contact) cells, which are usually processed in the process chamber of process equipment. Specifically, a layer of ultra-thin silicon oxide is first prepared on the back of the silicon wafer, and finally a layer of polysilicon is deposited. The two together form a passivation contact structure. The quality of the polysilicon layer is reflected by its film thickness. A polysilicon layer of reasonable thickness can protect the ultra-thin silicon oxide, that is, to avoid its damage, and can improve the battery performance of solar cells.

[0003] In order to ensure that the film thickness of the polysilicon layer of the prepared silicon wafer meets normal requirements, the film thickness of the polysilicon layer needs to be manually detected after each process is completed. However, this requires a lot of manpower to take out the wafer for testing and manually debug the process parameters on the host computer. Due to the differences in debugging techniques among different people and current manpower limitations, the timeliness of film thickness adjustment and the debugging effect are difficult to guarantee during manual debugging.

[0004] In summary, the related technologies have the problems of untimely film thickness adjustment, poor debugging effect and high labor cost. Summary of the invention

[0005] The present application discloses a process device and a processing method for solar cells, so as to solve the problems of untimely film thickness adjustment, poor debugging effect and high labor cost in the related art.

[0006] In order to solve the above technical problems, this application adopts the following technical solutions: A process equipment, comprising a process chamber, a main machine platform and a film thickness detection component, The process chamber is used for processing silicon wafers, the main station can adjust the process parameters of the process chamber, the film thickness detection device can detect the film thickness of the polysilicon layer of the silicon wafer, the film thickness detection device is communicatively connected with the main station, and when the film thickness is greater than a first preset threshold or less than a second preset threshold, the main station adjusts the process parameters.

[0007] A method for processing a solar cell is applied to the process equipment described above, wherein the silicon wafer comprises a first silicon wafer and a second silicon wafer, and the method comprises: detecting a film thickness of a polysilicon layer of the first silicon wafer taken out from the process chamber; Comparing the thickness of the polysilicon layer of the first silicon wafer with the first preset threshold and the second preset threshold; When the film thickness of the polysilicon layer of the first silicon wafer is greater than the first preset threshold or less than the second preset threshold, adjusting the process parameter; The second silicon wafer located in the process chamber is processed according to the process parameters.

[0008] The technical solution adopted in this application can achieve the following beneficial effects: In the present application, since the film thickness of the polysilicon layer of the silicon wafer can be detected by the film thickness detection part, and the film thickness detection part is connected to the main station in communication, when the film thickness is greater than the first preset threshold or less than the second preset threshold, that is, when the film thickness of the polysilicon layer of the silicon wafer processed by the process chamber does not meet the normal demand, the main station itself can adjust the process parameters of the process chamber, that is, no manual debugging is required, which can ensure the timeliness and debugging effect of the film thickness adjustment, and at the same time can reduce the labor cost to a certain extent, that is, save manpower while improving the quality of the silicon wafer. Therefore, the process equipment disclosed in the present application can solve the problems of untimely film thickness adjustment, poor debugging effect and high labor cost in the related technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 and Figure 2 All of them are structural block diagrams of process equipment disclosed in the embodiments of this application; Figures 3 to 5 All of them are flow charts of the processing method of the solar cell disclosed in the embodiments of the present application.

[0010] Description of reference numerals: 100-process chamber; 200-Host station; 300-film thickness detection parts; 400-Control platform; 500-Carrying device. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0012] The process equipment disclosed in the embodiments of the present application is described in detail below through specific embodiments and their application scenarios in conjunction with the accompanying drawings.

[0013] Please refer to Figure 1 and Figure 2 The present application discloses a process equipment, which includes a process chamber 100 , a mainframe 200 and a film thickness detection component 300 .

[0014] The process chamber 100 is used for processing silicon wafers, that is, the silicon wafers can be processed in the process chamber 100, and the main stage 200 can adjust the process parameters of the process chamber 100, that is, the main stage 200 is connected to the process chamber 100, so as to adjust the process parameters of the process chamber 100, and the process parameters may specifically include parameters such as processing temperature, processing time and the amount of processing gas introduced into the process chamber 100.

[0015] The film thickness detection part 300 can detect the film thickness of the polysilicon layer of the silicon wafer. Specifically, the silicon wafer is placed in the film thickness detection part 300, and the film thickness detection part 300 can automatically detect the film thickness of the polysilicon layer of the silicon wafer, and the film thickness detection part 300 is connected to the host station 200 for communication, that is, the film thickness data detected by the film thickness detection part 300 can be transmitted to the host station 200. When the film thickness is greater than the first preset threshold or less than the second preset threshold, the host station 200 can adjust the process parameters. It should be noted that the first preset threshold and the second preset threshold here are the processing range of the film thickness of the polysilicon layer of the silicon wafer. Under different process requirements, the processing range of the film thickness can be different.

[0016] In the present application, since the film thickness of the polysilicon layer of the silicon wafer can be detected by the film thickness detection member 300, and the film thickness detection member 300 is connected to the main stage 200 for communication, when the film thickness is greater than the first preset threshold or less than the second preset threshold, that is, when the film thickness of the polysilicon layer of the silicon wafer processed by the process chamber 100 does not meet the normal demand, the main stage 200 itself can adjust the process parameters of the process chamber 100, that is, no manual debugging is required, which can ensure the timeliness and debugging effect of the film thickness adjustment, and at the same time can reduce the labor cost to a certain extent, that is, save manpower while improving the quality of the silicon wafer. Therefore, the process equipment disclosed in the present application can solve the problems of untimely film thickness adjustment, poor debugging effect and high labor cost in the related technology.

[0017] In addition, since the present application can ensure the timeliness and debugging effect of the adjustment of the film thickness of the polysilicon layer of the silicon wafer, the present application can process a film thickness that meets the use requirements. When the polysilicon layer of the silicon wafer is subsequently heavily doped to form a high-low junction, the recombination rate of carriers on the back of the silicon wafer can be effectively reduced, further improving the conversion efficiency of the solar cell. At the same time, the polysilicon layer of appropriate thickness can provide sufficient protection for the ultra-thin silicon oxide layer, that is, the tunneling layer, and it is not easy to break through the tunneling layer in the subsequent phosphorus diffusion process, which increases the qualified rate of silicon wafers processed by the process chamber 100. In addition, the polysilicon layer of appropriate thickness can improve the short-circuit current and fill factor of the solar cell, thereby improving the battery performance of the solar cell.

[0018] At the same time, since the host station 200 itself can adjust the process parameters of the process chamber 100, this can avoid the problem of cumbersome control steps and heavy workload due to the need for manual adjustment, and at the same time avoid the problem of easy mis-touch resulting in wrong adjustment of parameters and reduced silicon wafer qualification rate. Moreover, in the present application, the film thickness measurement of the polysilicon layer of the silicon wafer and the debugging of the process parameters are all automatically operated by the process equipment, which can avoid the contact contamination of the silicon wafer by sweat, sebum, etc. that may be caused during the manual detection process, and at the same time reduce the high rework rate of the silicon wafer caused by large test errors.

[0019] Optionally, the process equipment may further include a control platform 400, which is in communication connection with the host platform 200 and the film thickness detection element 300, and the control platform 400 may compare the film thickness with the first preset threshold value and the second preset threshold value, that is, the control platform 400 may more accurately compare and reflect the size relationship between the detected film thickness and the first preset threshold value and the second preset threshold value, so that the host platform 200 may more accurately adjust the process parameters accordingly. Of course, in other embodiments, the process equipment may not include the control platform 400.

[0020] Optionally, the process equipment may further include a carrier 500, which is used to carry silicon wafers. Specifically, silicon wafers that have been processed in the process chamber 100 can be unloaded onto the carrier 500. The carrier 500 can specifically be a flower basket. The carrier 500 can transport silicon wafers to approach the film thickness detection part 300. At this time, the operator can manually transport the silicon wafers placed on the carrier 500 to the film thickness detection part 300 to facilitate detection by the film thickness detection part 300.

[0021] In another embodiment, the process equipment may further include a manipulator, which may transport the silicon wafer placed on the carrier 500 to the film thickness detection member 300 for detection by the film thickness detection member 300. It can be seen that in this embodiment, the silicon wafer placed on the carrier 500 is grasped by the manipulator, which can improve the efficiency of grasping the silicon wafer and avoid manual damage or contamination of the silicon wafer, that is, the whole process is more automated.

[0022] Optionally, refer to Figures 3 to 5 The present application also discloses a method for processing a solar cell, which is applied to the process equipment described above. The silicon wafer may include a first silicon wafer and a second silicon wafer. The method may include: S400 , detecting the film thickness of the polysilicon layer of the first silicon wafer taken out from the process chamber 100 .

[0023] Specifically, after the first silicon wafer is initially processed in the process chamber 100, the first silicon wafer can be unloaded from the process chamber 100 onto the above-mentioned carrier 500, that is, the first silicon wafer taken out from the process chamber 100, and the above-mentioned film thickness detection device 300 is used to detect the film thickness of the polysilicon layer of the first silicon wafer.

[0024] S500 , comparing the thickness of the polysilicon layer of the first silicon wafer with a first preset threshold and a second preset threshold.

[0025] Specifically, the film thickness detection component 300 can send the tested film thickness data to the control platform 400, and the control platform 400 can compare the film thickness of the polysilicon layer of the first silicon wafer with the first preset threshold and the second preset threshold, so as to determine whether the film thickness data is qualified.

[0026] S610 , when the film thickness of the polysilicon layer of the first silicon wafer is greater than a first preset threshold or less than a second preset threshold, adjusting the process parameters.

[0027] Specifically, when the control platform 400 determines that the film thickness data is unqualified, it means that the film thickness of the polysilicon layer of the first silicon wafer does not meet the process requirements, that is, the film thickness of the polysilicon layer of the first silicon wafer is greater than the first preset threshold or less than the second preset threshold. At this time, the film thickness detection component 300 sends an abnormal signal to the main station 200, and the main station 200 outputs an adjustment instruction through its internal algorithm and adjusts the process parameters of the process chamber 100, which may be to adjust the process parameters such as the processing temperature, processing time and the air intake volume of the process chamber 100.

[0028] S700 , processing the second silicon wafer in the process chamber 100 according to the process parameters.

[0029] Specifically, after adjusting the process parameters of the process chamber 100 , the process chamber 100 may process the second silicon wafer located in the process chamber 100 according to the process parameters, thereby processing a second silicon wafer that meets the process requirements.

[0030] In the present application, since the thickness of the polysilicon layer of the silicon wafer can be automatically measured and adjusted online through the film thickness detection component 300, the main station 200 and the control platform 400, the production line for processing silicon wafers can reach a higher level of automation and the process control capability can be reached to a higher level. Moreover, since no manual debugging is required, the timeliness and debugging effect of the film thickness adjustment can be ensured, and at the same time, the labor cost can be reduced to a certain extent, that is, manpower can be saved while improving the quality of silicon wafers.

[0031] Optionally, before step S400, that is, before detecting the film thickness of the polysilicon layer of the first silicon wafer taken out from the process chamber 100, the method may further include: S100 , taking out a plurality of first silicon wafers in the process chamber 100 .

[0032] Specifically, after the process chamber 100 has processed a plurality of first silicon wafers, an unloading device may be used to take out the plurality of first silicon wafers in the process chamber 100 and place them on the carrier 500 .

[0033] S200 , transporting a plurality of first silicon wafers to the film thickness detection unit 300 .

[0034] Specifically, the carrier device 500 may be used to transport the plurality of first silicon wafers to a position close to the film thickness detection element 300 .

[0035] S300 , extracting at least two first silicon wafers from a plurality of first silicon wafers for detection.

[0036] Specifically, the above-mentioned manipulator can be used to extract at least two first silicon wafers from the plurality of first silicon wafers and place them in the film thickness detection member 300, so as to facilitate the film thickness detection member 300 to perform detection. In this embodiment, since at least two first silicon wafers from the plurality of first silicon wafers are extracted to perform film thickness detection of the polysilicon layer, the overall detection error can be reduced. Of course, in other embodiments, the above-mentioned manipulator can be used to extract only one first silicon wafer from the plurality of first silicon wafers for detection.

[0037] Optionally, after step S700, that is, after processing the second silicon wafer in the process chamber 100 according to the process parameters, the method may further include: S800 , taking out a plurality of second silicon wafers in the process chamber 100 .

[0038] Specifically, after adjusting the process parameters, when the process chamber 100 has processed a plurality of second silicon wafers, the unloading device can be used again to take out the plurality of second silicon wafers in the process chamber 100 and place them on the carrier 500 .

[0039] S900 , transporting a plurality of second silicon wafers to the film thickness detection unit 300 .

[0040] Specifically, the carrier device 500 may be used to transport the plurality of second silicon wafers to a position close to the film thickness detection element 300 .

[0041] S1000 , extract at least two second silicon wafers from a plurality of second silicon wafers for detection.

[0042] Specifically, the above-mentioned robot arm can be used to extract at least two first silicon wafers from multiple second silicon wafers and place them in the film thickness detection part 300 to facilitate detection by the film thickness detection part 300. In this embodiment, since at least two second silicon wafers from multiple second silicon wafers are extracted for film thickness detection of the polysilicon layer, this can reduce the overall detection error.

[0043] S2100 , when the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, inspect at least one of the main stage 200 , the film thickness detection component 300 and the process chamber 100 .

[0044] Specifically, under normal circumstances, after the host station 200 has adjusted the process parameters of the process chamber 100 for the last time, the film thickness of the polysilicon layer of the second silicon wafer can meet normal requirements. If it does not meet the requirements, that is, when the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, it means that there is a problem with each device. At this time, at least one of the host station 200, the film thickness detection component 300 and the process chamber 100 can be repaired, which can effectively improve work efficiency and process management level. Of course, in other embodiments, when the film thickness of the polysilicon layer of the second silicon wafer is still greater than the first preset threshold or less than the second preset threshold, the host station 200 can adjust the process parameters again.

[0045] Optionally, refer to Figure 5 , step S2100 may specifically include, that is, when the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, repairing at least one of the host platform 200, the film thickness detection member 300 and the process chamber 100 may specifically include: S2110, when the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, issuing an alarm instruction.

[0046] Specifically, when the control platform 400 determines that the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, the control platform 400 may issue an alarm instruction to promptly remind maintenance personnel to perform maintenance, thereby further improving subsequent production efficiency. Of course, in other embodiments, the control platform 400 may not issue an alarm instruction.

[0047] S2120, transferring the second silicon wafer to the first transfer channel.

[0048] Specifically, the second silicon wafer that does not meet the process requirements can be transmitted to the first transmission channel, and the production line personnel can be notified for inspection to decide whether to rework.

[0049] S2130 , inspect at least one of the main platform 200 , the film thickness detection component 300 , and the process chamber 100 .

[0050] Specifically, when the control platform 400 issues an alarm command, maintenance personnel can quickly check and maintain at least one of the main maintenance station 200, the film thickness detection component 300 and the process chamber 100 to ensure that the subsequent process proceeds normally.

[0051] Optionally, the above method may further include: S620 , when the film thickness of the polysilicon layer of the first silicon wafer is between the first preset threshold and the second preset threshold, transmitting the first silicon wafer to the second transmission channel.

[0052] Specifically, when the management and control platform 400 determines that the film thickness of the polysilicon layer of the first silicon wafer is between the first preset threshold and the second preset threshold, this indicates that the film thickness of the polysilicon layer of the first silicon wafer meets the process requirements. At this time, the first silicon wafer can be transferred to the second transmission channel to facilitate the next processing step.

[0053] S2200 , when the film thickness of the polysilicon layer of the second silicon wafer is between the first preset threshold and the second preset threshold, transmitting the second silicon wafer to the second transmission channel.

[0054] Specifically, when the control platform 400 determines that the film thickness of the polysilicon layer of the second silicon wafer is also between the first preset threshold and the second preset threshold, this indicates that the film thickness of the polysilicon layer of the second silicon wafer meets the process requirements. At this time, the second silicon wafer can also be transmitted to the second transmission channel to facilitate the next processing. It can be seen that the qualified first silicon wafer and the second silicon wafer can be transmitted to the same second transmission channel, which can facilitate centralized processing, thereby facilitating subsequent processing and reducing the overall structural complexity. Of course, in other embodiments, the qualified first silicon wafer and the second silicon wafer can be transmitted to different transmission channels for subsequent processing.

[0055] Optionally, after step S2200, that is, when the film thickness of the polysilicon layer of the second silicon wafer is between the first preset threshold and the second preset threshold, after the second silicon wafer is transferred to the second transfer channel, the method may further include: S2300. Record and save process parameters to a database.

[0056] Specifically, after adjusting the process parameters of the process chamber 100, the film thickness of the polysilicon layer of the second silicon wafer processed by the process chamber 100 meets the process requirements, so the process parameters are correct. At this time, the host station 200 can record and save the process parameters to the database, and can also record and save the corresponding film thickness data to the database, and the tested film thickness data and adjusted process parameters can be automatically generated into reports for easy viewing, which can effectively improve work efficiency and process management level, and at the same time facilitate the subsequent direct retrieval of the process parameters from the database for processing other silicon wafers. Of course, in other embodiments, the host station 200 may not record and save the process parameters.

[0057] Optionally, the above method may further include: S3000, obtaining at least one of the maximum value, the minimum value and the average value of the film thickness of the polysilicon layer of the at least two second silicon wafers.

[0058] Specifically, the control platform 400 may obtain at least one of a maximum value, a minimum value, and an average value of the film thickness of the polysilicon layer of at least two second silicon wafers.

[0059] S4000 , display at least one of a maximum value, a minimum value, and an average value.

[0060] Specifically, the control platform 400 can obtain and display at least one of the maximum value, minimum value and average value of the film thickness of the polysilicon layer of the at least two second silicon wafers, that is, real-time monitoring can be performed through the visual interface, and the manufacturing capability of the process chamber 100 can be quickly analyzed through these data. Specifically, the better the manufacturing capability of the process chamber 100, the more stable the processing of the silicon wafer, and the closer the film thickness of the polysilicon layer of the silicon wafer is to the required film thickness. Of course, in other embodiments, the control platform 400 may not obtain and display at least one of the maximum value, minimum value and average value of the film thickness of the polysilicon layer of the at least two second silicon wafers.

[0061] In addition, the management and control platform 400 can also summarize and refresh the film thickness data of the polysilicon layer of silicon wafers processed by multiple process chambers 100 in real time, and obtain basic information of each process chamber 100 through automated communication, such as the serial number of the main station 200 corresponding to each process chamber 100, the serial number of each process chamber 100, and the setting location of each process chamber 100, etc., to facilitate centralized management.

[0062] The above embodiments of the present application focus on describing the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0063] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A process equipment, characterized in that: It comprises a process chamber (100), a main machine platform (200) and a film thickness detection component (300), The process chamber (100) is used for processing silicon wafers; the main stage (200) can adjust the process parameters of the process chamber (100); the film thickness detection component (300) can detect the film thickness of the polysilicon layer of the silicon wafer; the film thickness detection component (300) is communicatively connected with the main stage (200); when the film thickness is greater than a first preset threshold or less than a second preset threshold, the main stage (200) adjusts the process parameters.

2. The process equipment according to claim 1, characterized in that: The process equipment further comprises a control platform (400), wherein the control platform (400) is communicatively connected to the main machine (200) and the film thickness detection element (300), and the control platform (400) can compare the film thickness with the first preset threshold value and the second preset threshold value.

3. The process equipment according to claim 1, characterized in that: The process equipment further comprises a carrying device (500) and a robot, wherein the carrying device (500) is used to carry the silicon wafer, and the robot can transport the silicon wafer placed on the carrying device (500) to the film thickness detection component (300).

4. A method for processing a solar cell, applied to the process equipment according to any one of claims 1 to 3, characterized in that: The silicon wafer includes a first silicon wafer and a second silicon wafer, and the method includes: detecting the film thickness of the polysilicon layer of the first silicon wafer taken out from the process chamber (100); Comparing the thickness of the polysilicon layer of the first silicon wafer with the first preset threshold and the second preset threshold; When the film thickness of the polysilicon layer of the first silicon wafer is greater than the first preset threshold or less than the second preset threshold, adjusting the process parameter; The second silicon wafer located in the process chamber (100) is processed according to the process parameters.

5. The method according to claim 4, characterized in that Before detecting the film thickness of the polysilicon layer of the first silicon wafer taken out from the process chamber (100), the method further comprises: Taking out the first plurality of silicon wafers in the process chamber (100); transporting the plurality of first silicon wafers to the film thickness detection device (300); At least two of the first silicon wafers are selected from the plurality of first silicon wafers for detection.

6. The method according to claim 4, characterized in that After processing the second silicon wafer in the process chamber (100) according to the process parameters, the method further comprises: Taking out the plurality of second silicon wafers in the process chamber (100); transporting the plurality of second silicon wafers to the film thickness detection device (300); Selecting at least two of the second silicon wafers from the plurality of second silicon wafers for testing; When the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, at least one of the main machine (200), the film thickness detection component (300) and the process chamber (100) is inspected.

7. The method according to claim 6, characterized in that When the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, inspecting at least one of the main machine (200), the film thickness detection component (300) and the process chamber (100) specifically comprises: When the film thickness of the polysilicon layer of the second silicon wafer is greater than the first preset threshold or less than the second preset threshold, issuing an alarm instruction; transferring the second silicon wafer to the first transfer channel; Overhauling at least one of the main machine platform (200), the film thickness detection component (300), and the process chamber (100).

8. The method according to claim 6, characterized in that The method further comprises: When the film thickness of the polysilicon layer of the first silicon wafer is between the first preset threshold and the second preset threshold, transmitting the first silicon wafer to a second transmission channel; When the film thickness of the polysilicon layer of the second silicon wafer is between the first preset threshold and the second preset threshold, the second silicon wafer is transferred to the second transfer channel.

9. The method according to claim 8, characterized in that When the thickness of the polysilicon layer of the second silicon wafer is between the first preset threshold and the second preset threshold, after the second silicon wafer is transferred to the second transfer channel, the method further includes: The process parameters are recorded and saved in a database.

10. The method according to claim 6, characterized in that The method further comprises: Obtaining at least one of a maximum value, a minimum value, and an average value of the film thickness of the polysilicon layers of the at least two second silicon wafers; At least one of the maximum value, the minimum value, and the average value is displayed.

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