A testing device and measurement method for wafers of different sizes

Abstract

The present invention discloses a test device and a measurement method for wafers of different sizes, belonging to the field of integrated circuit test systems. The test device includes a frame, a linear motion assembly, a circular drive assembly, a stage, positioning clips, a fixing frame, a lifting assembly, and an elastic probe assembly. The linear motion assembly is horizontally arranged on the frame, the output end of the linear motion assembly is connected to the circular drive assembly, the output end of the circular drive assembly is connected to the stage, different-sized wafer limiting grooves are coaxially arranged on the stage, and positioning clips for wafer fixation are arranged on the wafer limiting grooves; the lifting assembly is located at the middle position of the fixing frame, the output end of the lifting assembly is connected to the elastic probe assembly, and the elastic probe assembly is located above the stage. The test device for wafers of different sizes according to the present invention can be applicable to the testing of wafers of different sizes, has a simple structure, a small volume, and good versatility.

Description

Technical Field

[0001] The present invention belongs to the field of integrated circuit test systems, and more specifically, relates to a test device and a measurement method for wafers of different sizes. Background Art

[0002] The four-probe method is a commonly used method for electrical characterization in the fields of materials science and semiconductors. Its principle is simple, it can eliminate the influence of contact resistance, and it has high test accuracy. Calculation formulas are derived from the thick-block principle and the thin-layer principle, and accurate measurement values can be obtained through corrections for thickness, edge effects, and test temperature. The design of the stage in a four-probe tester is very crucial, which directly determines the range of wafer sizes that the device can test and the test method.

[0003] Current test devices generally only target wafers of a single size model, with poor versatility. Especially for wafers larger than 12 inches, to accommodate the test requirements of wafers of different sizes, parameters such as the volume and weight of the test device will increase, and the structure is relatively complex. In this regard, there is a need to design a test device for wafers of different sizes, which has a simple structure and the characteristics of small volume and convenient wafer replacement, and solves the problem of incompatibility between the stage and the test of wafers of different specifications in the test system. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a test device and a measurement method for wafers of different sizes, aiming to solve the problems that existing test equipment can only measure wafers of a single size, has poor versatility, complex structure, and large volume.

[0005] To achieve the above purpose, the present invention provides a test device for wafers of different sizes, including a frame, a linear motion component, a circular drive component, a stage, a positioning clip, a fixing frame, a lifting component, and an elastic probe component, wherein:

[0006] The frame serves as an installation carrier, the linear motion component is horizontally arranged on the frame, the output end of the linear motion component is connected to the circular drive component, and the linear motion component can drive the circular drive component to move linearly;

[0007] The output end of the circular drive component is connected to the stage, the circular drive component and the stage are coaxially arranged and can drive the stage to rotate;

[0008] The stage is used for installing wafers, different-sized wafer limit grooves are coaxially arranged on the stage, and positioning clips for fixing wafers are provided on the wafer limit grooves;

[0009] The fixing frame is perpendicular to the length direction of the linear motion component and is fixed on the frame. The lifting component is located at the middle position of the fixing frame. The output end of the lifting component is connected to the elastic probe component, and the elastic probe component is located above the carrier table. The lifting component can drive the elastic probe component to move in the vertical direction.

[0010] Further, the linear motion component is a linear module. A first slider and a second slider that can move synchronously are provided on the linear module. The first slider is fixed to the annular driving component. The second slider is fixedly connected to the first slider through a connecting rod. A support roller component is provided on the second slider, and the support roller component contacts and assists in supporting the lower end surface of the carrier table.

[0011] Further, the annular driving component includes a driving motor and an annular guide rail. The output shaft of the driving motor is fixed to the connecting boss at the lower end of the carrier table. The slider on the annular guide rail is fixed to the lower end surface of the carrier table.

[0012] Further, threaded holes for fixing the positioning clips are provided on the wafer limiting groove. The positioning clip includes a positioning body. A soft isolation layer is provided on the side wall of the positioning body close to the wafer cut corner. A limiting portion is provided on the positioning body, and a soft isolation layer for contacting the wafer is also provided on the lower end surface of the limiting portion.

[0013] Further, an installation groove is provided on the second slider. The support roller component includes a rotating shaft vertically penetrating through the side wall of the installation groove. A bearing is sleeved in the middle of the rotating shaft. The bearing is located in the installation groove. Limiting rings are fitted on both sides of the bearing. Retaining rings are provided at both ends of the rotating shaft.

[0014] Further, the elastic probe component includes an L-shaped connecting plate fixed to the output end of the lifting component. A vertically arranged guide rail is provided in the middle of the L-shaped connecting plate. A connecting block is provided on the slider of the guide rail. A detection probe is fixed on the connecting block. The L-shaped connecting plate and the connecting block are slidably connected through a limiting bolt. A spring is sleeved on the limiting bolt. One end of the spring abuts against the connecting block, and the other end abuts against the L-shaped connecting plate. The spring has a tendency to drive the connecting block to move downward.

[0015] Further, an auxiliary pressing component for fixing the wafer is detachably provided on the wafer limiting groove. The auxiliary pressing component includes a connecting bolt for threaded connection with the wafer limiting groove. An adjusting nut and a pressing plate are sequentially arranged on the connecting bolt from top to bottom. A rubber pressing piece is attached to the lower end of the pressing plate.

[0016] Further, the testing device further includes a filling wafer. The number of the filling wafers is the same as that of the wafer limiting grooves, and their sizes correspond to each other. The thickness of the filling wafer is equal to the height of the wafer limiting groove, and it is used to be placed under the wafer to assist in supporting during testing.

[0017] Further, the linear motion assembly, the annular drive assembly, the lifting assembly, and the elastic probe assembly are all electrically connected to the upper computer.

[0018] A testing method for wafers of different sizes includes the following steps:

[0019] S1. The linear motion assembly drives the carrier to move to the loading position, places the wafer in the wafer limiting groove, and fixes it with a positioning clip.

[0020] S2. The linear motion assembly and the annular drive assembly drive the carrier to move to the first detection point as a whole. The lifting assembly drives the elastic probe assembly to descend and contact the detection point on the wafer, measures the resistance value, calculates the resistivity parameter and records it, and then the lifting assembly drives the elastic probe assembly to reset.

[0021] S3. The linear motion assembly and the annular drive assembly drive the carrier to move to the second detection point as a whole. The lifting assembly drives the elastic probe assembly to descend and contact the detection point on the wafer, measures the resistance value, calculates the resistivity parameter and records it, and then the lifting assembly drives the elastic probe assembly to reset.

[0022] S4. According to the measurement sequence, repeat step S3 to complete the measurement of all detection points in turn. Record the resistivity parameters of each detection point, transmit them to the upper computer and display them on the display screen. The linear motion assembly drives the carrier to move to the unloading position, remove the positioning clip, and take out the wafer; replace wafers of different sizes, and repeat steps S1 - S4 to complete the measurement of wafers of different sizes.

[0023] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects are achieved:

[0024] (1) It is provided with a linear motion assembly, an annular drive assembly, a lifting assembly, and an elastic probe assembly, and wafer limiting holes suitable for wafers of different sizes are coaxially arranged on the carrier, which can detect wafers of different sizes with good versatility. Through the linear motion assembly and the annular drive assembly, the adjustment of the measurement points of the wafer in the plane can be realized, the structure is simplified, and compared with the use of a cross module, the volume is reduced.

[0025] (2) Additionally, the elastic probe assembly includes an L-shaped connecting plate, a guide rail, a connecting block, and a detection probe. The L-shaped connecting plate and the connecting block are slidably connected by a limit bolt, and a spring is sleeved on the limit bolt to prevent excessive downward pressure when the detection probe contacts the detection point and damage the wafer.

[0026] (3) Meanwhile, a roller support assembly is provided to assist in supporting the stage when the stage rotates, making the movement of the stage more stable and improving the measurement accuracy.

[0027] (4) In addition, the positioning clip includes a positioning body, and a soft layer is provided on the side wall of the positioning body close to the wafer cut corner; a limiting portion is provided on the positioning body, and a soft layer for contacting the wafer is also provided on the lower end surface of the limiting portion to ensure that the wafer surface is not damaged while fixing the wafer.

[0028] (5) Moreover, an auxiliary downward pressure assembly is provided to prevent the wafer from loosening during rotation and further improve the reliability of wafer fixation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a test device for wafers of different sizes provided by the present invention;

[0030] Figure 2 is a front view of a test device for wafers of different sizes provided by the present invention;

[0031] Figure 3 is a schematic diagram of wafer installation;

[0032] Figure 4 is a cross-sectional view of the stage of a test device for wafers of different sizes provided by the present invention;

[0033] Figure 5 is Figure 4 a partial enlarged view at C in

[0034] Figure 6 is Figure 4 a partial enlarged view at D in

[0035] Figure 7 is a schematic structural diagram of the roller support assembly of a test device for wafers of different sizes provided by the present invention;

[0036] Figure 8 is a cross-sectional view of the roller support assembly of a test device for wafers of different sizes provided by the present invention;

[0037] Figure 9 is a schematic structural diagram of the elastic probe assembly of a test device for wafers of different sizes provided by the present invention.

[0038] The structures corresponding to the various numerical markings in the attached drawings are as follows: 1 - frame, 2 - linear motion assembly, 21 - first slider, 22 - second slider, 23 - connecting rod, 24 - support roller assembly, 3 - annular drive assembly, 4 - carrier table, 41 - wafer limit groove, 5 - positioning clip, 51 - positioning body, 511 - limiting portion, 512 - soft spacer layer, 6 - fixing bracket, 7 - lifting assembly, 8 - elastic probe assembly, 81 - L-shaped connecting plate, 82 - guide rail, 83 - connecting block, 84 - detection probe, 85 - limiting bolt, 86 - spring, 9 - fixing seat, 10 - auxiliary pressing-down assembly, 101 - connecting bolt, 102 - adjusting nut, 103 - pressing plate, 104 - rubber pressing sheet. Detailed implementation manners

[0039] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the attached drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0040] Refer to Figures 1 to 9 , the present invention provides a test device for wafers of different sizes, which is used to measure the resistance of the entire area of the wafer, and calculate the resistivity through the measured resistance. The existing qualified range of wafer resistivity is 1 - 100 Ω·cm. As Figure 3 shown, A is the wafer, and a is the cut corner provided on the wafer. The cut corner is used for positioning when the wafer is fixed.

[0041] The test device includes a frame 1, a linear motion assembly 2, an annular drive assembly 3, a carrier table 4, a positioning clip 5, a fixing bracket 6, a lifting assembly 7, and an elastic probe assembly 8. Each component will be described in detail below with reference to the embodiments.

[0042] The frame 1 serves as an installation carrier for installing other components; the linear motion assembly 2 is horizontally arranged on the frame and is located at the middle position of the frame 1. The output end of the linear motion assembly 2 is connected to the annular drive assembly 3. The annular drive assembly 3 has a circular shape, and its output end can rotate around the central axis. The linear motion assembly 2 can drive the annular drive assembly 3 to move linearly;

[0043] The output end of the annular drive assembly 3 is connected to the carrier table 4. The annular drive assembly 3 and the carrier table 4 are coaxially arranged and can drive the carrier table 4 to rotate. By using the linear motion assembly 2 and the annular drive assembly 3, the carrier table 4 can be driven to position the wafer within the plane range, which simplifies the structure and reduces the volume compared with using a cross module.

[0044] The stage 4 is used to mount the wafer. To accommodate wafers of different sizes, different-sized wafer limiting grooves 41 are coaxially provided on the stage 4. Each wafer limiting groove corresponds to a wafer of a specific size, thus enabling the testing of wafers of different sizes. To facilitate the mounting and positioning of the wafer, positioning clips 5 for fixing the wafer are provided on the wafer limiting grooves 41.

[0045] The fixing frame 6 straddles above the linear motion component 2, is perpendicular to the length direction of the linear motion component 2 and is fixed to the frame 1. The lifting component 7 is located at the middle position of the fixing frame 6. To fix the lifting component 7, a fixing seat 9 is provided on the fixing frame; the output end of the lifting component 7 is connected to the elastic probe component 8. In this embodiment, to facilitate the precise adjustment of the lifting of the elastic probe component 8, the lifting component 7 adopts a linear module, which is driven by a motor and a lead screw, and has a relatively high adjustment accuracy; the elastic probe component 8 is located above the stage 4; the lifting component 7 can drive the elastic probe component 8 to move in the vertical direction.

[0046] In this embodiment, the linear motion component 2 is a linear module. The first slider 21 and the second slider 22 that can move synchronously are provided on the linear module. The first slider 21 is fixed to the annular drive component 3, and the second slider 22 is fixedly connected to the first slider 21 through a connecting rod 23. To support the rotation process of the stage 4 and prevent the stage 4 from shaking during rotation, which may affect the testing accuracy, a support roller assembly 24 is provided on the second slider 22, and the support roller assembly 24 contacts and assists in supporting the lower end surface of the stage 4.

[0047] Specifically, the annular drive component 3 includes a drive motor and an annular guide rail. The output shaft of the drive motor is fixed to the connecting boss at the lower end of the stage, and the slider on the annular guide rail is fixed to the lower end surface of the stage.

[0048] The positioning clip 5 is used to mount and position the wafer. To facilitate the disassembly and assembly of the positioning clip 5, threaded holes for fixing the positioning clip 5 are provided on the wafer limiting grooves 41. Specifically, in this embodiment, the positioning clip 5 includes a positioning main body 51. To avoid damaging the surface of the wafer during the process of fixing the wafer, a protective layer needs to be provided at all places on the positioning main body 51 that contact the wafer. Specifically, a soft isolation layer 512 is provided on the side wall of the positioning main body 51 near the wafer cut corner, and a soft isolation layer 512 for contacting the wafer is also provided on the lower end surface of the limiting part 511 on the positioning main body 51. The soft isolation layer is mostly made of materials such as rubber or silica gel.

[0049] To facilitate the installation and limitation of the support roller assembly 24, an installation groove 221 is provided on the second slider 22. In this embodiment, the support roller assembly 24 includes a rotating shaft 241 vertically penetrating the side wall of the installation groove 221. A bearing 242 is sleeved in the middle of the rotating shaft 241, and the bearing 242 is located within the installation groove 221. To prevent the bearing 242 from rubbing against the inner wall of the installation groove 221 and getting stuck during rotation, limiting rings 243 are fitted on both sides of the bearing 242. The limiting rings 243 are in contact with the inner ring of the bearing 242. To install and limit the rotating shaft 241, retaining rings 244 are provided at both ends of the rotating shaft 241.

[0050] The elastic probe assembly 8 is used to contact the wafer and measure the resistivity of the detection point. Since the wafer is easily damaged under external force, therefore, setting the elastic probe assembly 8 can avoid excessive pressure on the wafer. In this embodiment, the elastic probe assembly 8 includes an L-shaped connecting plate 81 fixed to the output end of the lifting assembly 7. A vertical guide rail 82 is provided in the middle of the L-shaped connecting plate 81. A connecting block 83 is provided on the slider of the guide rail 82. A detection probe 84 is fixed on the connecting block 83. The L-shaped connecting plate 81 and the connecting block 83 are slidably connected by a limiting bolt 85. A spring 86 is sleeved on the limiting bolt 85. One end of the spring 86 abuts against the connecting block 83, and the other end abuts against the L-shaped connecting plate 81. The spring 86 has a tendency to drive the connecting block 83 to move downward. During measurement, the end of the detection probe 84 contacts the detection point, and the measured voltage signal is transmitted to the resistance measurement module inside the detection probe 84 to obtain a resistance value, and the resistivity parameter value is obtained through internal program conversion.

[0051] To achieve the automatic control of the measuring device, the linear motion assembly 2, the ring drive assembly 3, the lifting assembly, and the elastic probe assembly 8 are all electrically connected to the upper computer.

[0052] Since the wafer rotates under the drive of the ring drive assembly 3, a certain centrifugal force will be generated. To further improve the detection efficiency and increase the rotation speed of the ring drive assembly 3, and to prevent the wafer from being thrown out of the wafer limiting groove 41, an auxiliary pressing assembly 10 for fixing the wafer is detachably provided on the wafer limiting groove 41, which cooperates with the positioning clip 5 to limit the axial position of the wafer and further improve the reliability of wafer fixation. Specifically, as Figure 6 shown, the auxiliary pressing assembly 10 includes a bolt 101 for threaded connection with the wafer limiting groove. An adjusting nut 102 and a pressing plate 103 are successively arranged on the bolt 101 from top to bottom. A rubber pressing sheet 104 is fitted to the lower end of the pressing plate 103. When the rotation speed is relatively fast, tightening the adjusting nut 102 downward can drive the pressing plate 103 to move downward, so that the rubber pressing sheet 104 is in contact with and presses the upper end surface of the wafer.

[0053] Since the test device for wafers of different sizes according to the present invention is applicable to the test of wafers with larger sizes, and the wafer size is relatively large, it is necessary to support the wafer. Therefore, the test device further includes a filling wafer B. The number of filling wafers B is the same as that of the wafer limiting grooves, and their sizes correspond to each other. Moreover, the thickness of the filling wafer is equal to the height of the wafer limiting groove, which is used to be placed under the wafer to assist in supporting during the test.

[0054] The present invention also provides a test method for wafers of different sizes, including the following steps:

[0055] S1. The linear motion component drives the carrier stage to move to the loading position, places the wafer in the wafer limiting groove, and fixes it with a positioning clip;

[0056] S2. The linear motion component and the annular drive component drive the entire carrier stage to move to the first detection point. The lifting component drives the elastic probe component to descend, so that the detection probes in the elastic probe component contact the detection points on the wafer, measure the resistance value, calculate the resistivity parameter and record it. Then the lifting component drives the elastic probe component to reset;

[0057] S3. The linear motion component and the annular drive component drive the entire carrier stage to move to the second detection point. The lifting component drives the elastic probe component to descend, so that the detection probes in the elastic probe component contact the detection points on the wafer, measure the resistance value, calculate the resistivity parameter and record it. Then the lifting component drives the elastic probe component to reset;

[0058] S4. According to the measurement sequence, repeat step S3 to complete the measurement of all detection points in turn. Record the resistivity parameters of each detection point, then transmit them to the host computer and display them on the display screen. The linear motion component drives the carrier stage to move to the unloading position, remove the positioning clip, and take out the wafer; replace wafers of different sizes, and repeat steps S1 - S4 to complete the measurement of wafers of different sizes.

[0059] Among them, in step S1, if the rotation speed of the annular drive component 3 is relatively fast, it is also necessary to install the auxiliary pressing component 10; in step S4, when measuring wafers with larger sizes, it is also necessary to install filling wafers in all the wafer limiting grooves under the wafer before fixing the wafer.

[0060] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention, and are not used to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A testing device for wafers of different sizes, characterized in that: it includes a machine frame (1), a linear motion component (2), a circular drive component (3), a carrier table (4), a positioning clip (5), a fixing frame (6), a lifting component (7) and an elastic probe component (8), wherein: The machine frame (1) serves as an installation carrier, the linear motion component (2) is horizontally arranged on the machine frame, the output end of the linear motion component (2) is connected to the circular drive component (3), and the linear motion component (2) can drive the circular drive component (3) to move linearly; The output end of the circular drive component (3) is connected to the carrier table (4), the circular drive component (3) and the carrier table (4) are coaxially arranged and can drive the carrier table (4) to rotate; The carrier table (4) is used for installing wafers, different-sized wafer limiting grooves (41) are coaxially arranged on the carrier table (4), and positioning clips (5) for fixing the wafers are arranged on the wafer limiting grooves (41); The fixing frame (6) is perpendicular to the length direction of the linear motion component (2) and is fixed on the machine frame (1), the lifting component (7) is located at the middle position of the fixing frame (6), the output end of the lifting component (7) is connected to the elastic probe component (8), and the elastic probe component (8) is located above the carrier table (4); the lifting component (7) can drive the elastic probe component (8) to move in the vertical direction.

2. The testing device for wafers of different sizes according to claim 1, characterized in that: The linear motion component (2) is a linear module, a first slider (21) and a second slider (22) that can move synchronously are arranged on the linear module, the first slider (21) is fixed to the circular drive component (3), the second slider (22) is fixedly connected to the first slider (21) through a connecting rod (23), a support roller assembly (24) is arranged on the second slider (22), and the support roller assembly (24) contacts and supports the lower end surface of the carrier table (4).

3. The testing device for wafers of different sizes according to claim 1, characterized in that: The circular drive component (3) includes a drive motor and a circular guide rail, the output shaft of the drive motor is fixed to the connecting boss at the lower end of the carrier table (4), and the slider on the circular guide rail is fixed to the lower end surface of the carrier table (4).

4. The testing device for wafers of different sizes according to claim 1, characterized in that: Threaded holes for fixing the positioning clip (5) are opened on the wafer limiting groove (41), the positioning clip (5) includes a positioning main body (51), a soft isolation layer is arranged on the side wall of the positioning main body (51) close to the wafer cut corner, a limiting part (511) is arranged on the positioning main body (51), and a soft isolation layer for contacting the wafer is also arranged on the lower end surface of the limiting part (511).

5. The testing device for wafers of different sizes according to claim 2, characterized in that: An installation groove (221) is formed in the second slider (22). The support roller assembly (24) includes a rotating shaft (241) vertically penetrating through the side wall of the installation groove (221). A bearing (242) is sleeved in the middle of the rotating shaft (241). The bearing (242) is located in the installation groove (221). Limiting rings (243) are attached to both sides of the bearing (242). Retaining rings (244) are provided at both ends of the rotating shaft (241).

6. The test device for wafers of different sizes according to claim 1, characterized in that: The elastic probe assembly (8) includes an L-shaped connecting plate (81) fixed to the output end of the lifting assembly (7). A vertically arranged guide rail (82) is provided in the middle of the L-shaped connecting plate (81). A connecting block (83) is provided on the slider of the guide rail (82). A detection probe (84) is fixed to the connecting block (83). The L-shaped connecting plate (81) and the connecting block (83) are slidably connected by a limiting bolt (85). A spring (86) is sleeved on the limiting bolt (85). One end of the spring (86) abuts against the connecting block (83), and the other end abuts against the L-shaped connecting plate (81). The spring (86) has a tendency to drive the connecting block (83) to move downward.

7. The test device for wafers of different sizes according to claim 1, characterized in that: A removable auxiliary pressing-down assembly (10) for fixing the wafer is further provided on the wafer limiting groove (41). The auxiliary pressing-down assembly (10) includes a connecting bolt (101) for threadedly connecting with the wafer limiting groove. An adjusting nut (102) and a pressing plate (103) are sequentially arranged on the connecting bolt (101) from top to bottom. A rubber pressing sheet (104) is attached to the lower end of the pressing plate (103).

8. The test device for wafers of different sizes according to claim 1, characterized in that: The test device further includes filling wafers. The number and size of the filling wafers correspond to those of the wafer limiting grooves (41), and the thickness of the filling wafers is equal to the height of the wafer limiting grooves (41), which are used to be placed under the wafer for auxiliary support during testing.

9. The test device for wafers of different sizes according to claim 1, characterized in that: The linear motion assembly (2), the circular driving assembly (3), the lifting assembly (7), and the elastic probe assembly (8) are all electrically connected to the upper computer.

10. A method for testing wafers of different sizes using the test device according to any one of claims 1-9, comprising the following steps: S1. The linear motion assembly drives the carrier table to move to the loading position, places the wafer in the wafer limiting groove, and fixes it with a positioning clip; S2. The linear motion assembly and the circular driving assembly drive the entire carrier table to move to the first detection point. The lifting assembly drives the elastic probe assembly to descend and contact the detection point on the wafer, measures the resistance value, calculates the resistivity parameter, and the lifting assembly drives the elastic probe assembly to reset; S3. The linear motion component and the ring drive component drive the entire stage to move to the second detection point. The lifting component drives the elastic probe component to descend and contact the detection point on the wafer, measure the resistance value, calculate the resistivity parameter, and the lifting component drives the elastic probe component to reset; S4. According to the measurement sequence, repeat step S3 to complete the measurement of all detection points in turn. Record the resistivity parameters of each detection point, transmit them to the host computer and display them on the display screen. The linear motion component drives the stage to move to the unloading position, remove the positioning clip, and take out the wafer; replace wafers of different sizes, repeat steps S1 - S4 to complete the measurement of wafers of different sizes.

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