Measuring device
By using a laser sensor to measure the spacing between the focusing ring and the cover ring and the wafer without contact, the problem of limited installation accuracy in the prior art is solved, the measurement accuracy and etching yield are improved, and the production cost is reduced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-20
- Publication Date
- 2026-04-03
AI Technical Summary
In existing technologies, the installation accuracy of the focusing ring and the cover ring is limited by the operator's sense and experience, resulting in a decrease in etching yield and an increase in production costs.
A laser sensor is used to measure the distance between the focusing ring and the cover ring and the wafer in a non-contact manner. The circumferential measurement is performed by moving the laser sensor, which ensures the accuracy and precision of the measurement and reduces human error.
This improved the accuracy of measuring the spacing between the focusing ring and the wafer, as well as between the cover ring and the wafer, reducing scrap rate and production costs, and ensuring the etching effect of the etching machine.
Smart Images
Figure CN224080935U_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to the field of semiconductor technology, and more specifically, to a measuring device. Background Technology
[0002] In the semiconductor plasma etching process, a focusing ring is used to focus the plasma onto the wafer, thereby providing uniformity of the process, while a cover ring is used to protect the focusing ring and prevent it from being exposed to the plasma environment and being damaged too quickly.
[0003] In related technologies, the focusing ring and cover ring are installed manually by operators, who then move them circumferentially between the focusing ring and cover ring and the wafer using shims (such as feeler gauges) to control the spacing between the focusing ring and cover ring and the wafer. However, the focusing ring and cover ring need to be frequently disassembled for installation and subsequent maintenance. Therefore, the above-mentioned method of manually controlling the spacing is easily affected by the operator's own feelings and experience, which limits the installation accuracy, thereby reducing the etching yield and increasing the scrap rate and production costs. Utility Model Content
[0004] The purpose of this disclosure is to provide a measuring device that can improve the measurement accuracy of the spacing distance between the focusing ring and the wafer, and between the cover ring and the wafer, so as to at least partially solve the above-mentioned technical problems.
[0005] To achieve the above objectives, this disclosure provides a measuring device for an etching machine, the etching machine including a focusing ring assembly and a base, the measuring device comprising:
[0006] Base, connected to the base; and
[0007] A measuring component, connected to the base, includes a laser sensor adapted to be disposed above the base and the focusing ring assembly, the laser sensor being used for non-contact circumferential measurement of the radial distance between the base and the focusing ring assembly.
[0008] Optionally, the focusing ring assembly includes a focusing ring and a cover ring, and the measuring component is used to detect a first distance between the outer edge of the base and the inner edge of the focusing ring, and / or a second distance between the outer edge of the base and the inner edge of the cover ring.
[0009] Optionally, the measuring assembly includes a support frame rotatably connected to the base, and the laser sensor is connected to the support frame to be able to move circumferentially about the axis of the base, wherein the measuring light emitted by the laser sensor is parallel to the axis of the base.
[0010] Optionally, the support frame includes a first support rod and a second support rod, the first support rod being adapted to be connected to the base, and the second support rod being connected to the first support rod and used to mount the laser sensor.
[0011] Optionally, the first support rod is rotatably connected to the base, or the second support rod is rotatably connected to the first support rod.
[0012] Optionally, the axis of the first support rod is parallel to the axis of the base, and / or the axis of the second support rod is perpendicular to the axis of the base.
[0013] Optionally, a level is provided on the second support rod; and / or,
[0014] The measuring component also includes a controller adapted to adjust the diameter of the measuring light emitted by the laser sensor.
[0015] Optionally, the second support rod is lockably slidably connected to the first support rod, and / or the length of the second support rod is adjustable to adjust the distance between the laser sensor and the first support rod.
[0016] Optionally, a distance sensor is provided between the first support rod and the second support rod, and / or, a distance sensor is provided between the laser sensor and the first support rod.
[0017] Optionally, the base has the same radial dimension as the wafer.
[0018] Through the above technical solution, a laser sensor can be used to measure the radial distance between the base and the focusing ring assembly. Specifically, the diameter of the measuring light emitted by the laser sensor can be equal to the aforementioned radial distance. The measuring light shines from top to bottom between the base and the focusing ring assembly, and the radial distance can be measured circumferentially by, for example, the movement of the laser sensor. This measurement process is not limited by the operator's senses or experience, and the measurement accuracy and precision are high. Furthermore, the measurement process does not require contact with the focusing ring assembly, reducing the possibility of damage to the focusing ring assembly and ensuring its normal function.
[0019] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description
[0020] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:
[0021] Figure 1This is a schematic diagram of the overall structure of the measuring device provided in an exemplary embodiment of this disclosure.
[0022] Explanation of reference numerals in the attached figures
[0023] 10. Measuring device; 20. Focusing ring assembly; 201. Focusing ring; 202. Covering ring; 30. Base;
[0024] 1. Base; 2. Measuring component; 21. Laser sensor; 22. Support frame; 221. First support rod; 222. Second support rod; 23. Controller; 3. Level; 4. Distance sensor;
[0025] D1, first distance; D2, second distance. Detailed Implementation
[0026] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.
[0027] In this disclosure, unless otherwise stated, "inner" and "outer" refer to the interior and exterior of the outline of the corresponding component; "far" and "near" refer to the distance of the corresponding component relative to another component in terms of spatial position. Furthermore, the terms "first," "second," etc., used in this disclosure are for distinguishing one element from another and do not have sequential or importance. When the following description relates to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements.
[0028] refer to Figure 1 As shown, this disclosure provides a measuring device 10 for an etching machine. The etching machine includes a focusing ring assembly 20 and a base 30. The measuring device 10 includes a base 1 and a measuring component 2, wherein the base 1 is connected to the base 30; the measuring component 2 is connected to the base 1 and includes a laser sensor 21 adapted to be disposed above the base 1 and the focusing ring assembly 20. The laser sensor 21 is used to non-contactly measure the radial distance between the base 1 and the focusing ring assembly 20 in the circumferential direction.
[0029] Through the above technical solution, the laser sensor 21 can be used to measure the radial distance between the base 1 and the focusing ring assembly 20. Specifically, the diameter of the measuring light emitted by the laser sensor 21 can be equal to the aforementioned radial distance. The measuring light shines from top to bottom between the base 1 and the focusing ring assembly 20, and the radial distance can be measured circumferentially by, for example, the movement of the laser sensor 21. When the radial distance requirement is met, the measuring light shines on the base 30 portion between the base 1 and the focusing ring assembly 20, at which point the green light of the laser sensor 21 illuminates. When the radial distance requirement is not met, the measuring light at least partially shines on the focusing ring assembly 20, at which point the red light of the laser sensor 21 illuminates. The above measurement process is not limited by the operator's senses or experience, and the measurement accuracy and precision are high. Furthermore, the above measurement process does not require contact with the focusing ring assembly 20, which reduces the possibility of damaging the focusing ring assembly 20 and ensures the normal function of the focusing ring assembly 20.
[0030] Understandably, the distance between the laser sensor 21 and the base 30 is different from the distance between the laser sensor 21 and the focusing ring assembly 20. Therefore, before measuring the distance using the laser sensor 21, a distance threshold can be set via a hardware button, supporting software, or communication interface. The laser sensor 21 then measures the distance, comparing the measured distance with the preset distance threshold to determine the radial distance between the base 1 and the focusing ring assembly 20. For example, if the distance threshold is set equal to the distance between the laser sensor 21 and the base 30, then when the radial distance meets the requirement, the measuring light emitted by the laser sensor 21 illuminates the portion of the base 30 between the base 1 and the focusing ring assembly 20, and the measured distance is the same as the distance threshold, at which point the green light of the laser sensor 21 illuminates. If the radial distance does not meet the requirement, the measuring light emitted by the laser sensor 21 at least partially illuminates the focusing ring assembly 20, and the measured distance differs from the distance threshold, at which point the red light of the laser sensor 21 illuminates.
[0031] Furthermore, the aforementioned base 30 can be, for example, an electrostatic chuck (ESC). During measurement, the measuring component 2 is mounted on the electrostatic chuck via the base 1, and then the focusing ring component 20 is mounted on the electrostatic chuck. Subsequently, the radial distance between the base 1 and the focusing ring component 20 is measured by the laser sensor 21 to position the focusing ring component 20, ensuring that the aforementioned radial distance meets the etching requirements, thereby guaranteeing the etching effect of the subsequent etching machine on the wafer.
[0032] After the measurement is completed, the measuring device 10 is detached from the base 30, and then the wafer is installed. The wafer is arranged concentrically with the base 1. For example, the wafer can be positioned and installed using a notch formed on the wafer. Taking the base 30 as an electrostatic chuck as an example, the surface of the electrostatic chuck can be designed with positioning grooves or positioning pins that match the notch on the wafer. When placing the wafer, the notch is engaged with the positioning groove or positioning pin. For example, with an inner diameter of 300mm for the wafer, the notch width is generally 1mm to 1.25mm.
[0033] In some embodiments, the radial dimensions of the base 1 and the wafer can be equal. Thus, after the radial distance between the base 1 and the focusing ring assembly 20 is measured as described above, the wafer is installed in the same position as the base 1, thereby completing the positioning and installation between the wafer and the focusing ring assembly 20. Then, the wafer can be etched by an etching machine.
[0034] It is understood that a notch, similar to or the same as the wafer, may be provided on the base 1 for positioning on a base 30, such as an electrostatic chuck. Furthermore, the base 1 may be larger or smaller than the radial dimension of the wafer, and the diameter of the measuring light emitted by the laser sensor 21 must be adjusted (decrease or increase) accordingly, but this disclosure is not limited thereto.
[0035] In some embodiments, reference Figure 1 As shown, the focusing ring assembly 20 may include a focusing ring 201 and a cover ring 202. The radial dimensions of both the focusing ring 201 and the cover ring 202 are larger than the radial dimension of the base 1. The focusing ring 201 and the cover ring 202 are disposed on the circumferential outer side of the base 1 with a gap. The cover ring 202 at least partially covers the focusing ring 201. The measuring assembly 2 is used to detect a first distance D1 between the outer edge of the base 1 and the inner edge of the focusing ring 201, and / or a second distance D2 between the outer edge of the base 1 and the inner edge of the cover ring 202.
[0036] In processes such as plasma etching, the focusing ring 201 serves several purposes. Wafer edges are prone to uneven etching (edge effect) due to plasma density gradients. The focusing ring 201 optimizes the electric field strength in the edge region, resulting in a more uniform ion energy distribution and reducing over-etching or under-etching at the edges. Furthermore, by adjusting the electric field distribution of the plasma sheath, it guides ions to be perpendicularly incident on the wafer surface, thereby enhancing the directionality (anisotropy) of the etching. The focusing ring 201 is typically made of silicon carbide or silicon to reduce parasitic etching in the plasma and maintain process stability.
[0037] The capping ring 202 serves several functions: protecting the focusing ring 201 from rapid damage due to exposure to the plasma environment; adjusting the edge plasma density and mean free path through structural design (e.g., wedge-shaped ring, tilt angle) to improve overall etching uniformity; and covering the electrode (e.g., an electrostatic chuck) to prevent direct plasma erosion of the electrode surface, extending equipment life. Simultaneously, its surface can adsorb byproducts generated during etching (e.g., polymers, metal ions), preventing these substances from redepositing on the wafer and causing defects. The capping ring 202 is typically made of quartz, silicon carbide, or doped silicon.
[0038] Therefore, it is understandable that the focusing ring 201 and the cover ring 202 are key components for optimizing etching uniformity, protecting equipment, and improving process stability. Maintaining an appropriate distance between the focusing ring 201 and the cover ring 202 and the wafer is crucial for their proper functioning. For example, if the focusing ring 201 is too close to the wafer, its electric field enhancement effect on the edge region is too strong, causing ion energy to concentrate at the wafer edge, resulting in over-etching. If the focusing ring 201 is too far from the wafer, the edge electric field strength is insufficient, weakening ion guidance and causing the edge etching rate to be lower than the central region, resulting in "insufficient edge etching." If the cover ring 202 is too close to the wafer, it blocks the plasma incident path at the wafer edge, leading to a decrease in edge plasma density and a significant drop in etching rate, resulting in "edge etching depressions." If the cover ring 202 is too far from the wafer, the protection of the electrode by the cover ring 202 will fail, and the plasma will directly bombard the edge of the electrode, causing corrosion on the electrode surface (such as oxidation of the metal electrode and peeling off of the ceramic layer), affecting the life of the equipment and the stability of wafer adsorption.
[0039] In the actual measurement process, exemplarily, the focusing ring 201 is first mounted on the electrostatic chuck, and then the laser sensor 21 emits a measuring light to detect the first distance D1 between the outer edge of the base 1 and the inner edge of the focusing ring 201. Then, the cover ring 202 is mounted on the electrostatic chuck, and the diameter of the measuring light emitted by the laser sensor 21 is adjusted to detect the second distance D2 between the outer edge of the base 1 and the inner edge of the cover ring 202. Alternatively, the focusing ring 201 is first mounted on the electrostatic chuck, and then the cover ring 202 is mounted on the electrostatic chuck. The laser sensor 21 first emits a measuring light to detect the first distance D1 between the outer edge of the base 1 and the inner edge of the focusing ring 201, and then the diameter of the measuring light emitted by the laser sensor 21 is adjusted to detect the second distance D2 between the outer edge of the base 1 and the inner edge of the cover ring 202. This disclosure is not limited thereto.
[0040] It is understood that, for example, in the above-described measurement process of the first distance D1, the preset distance threshold can be the distance between the laser sensor 21 and the base 30. When the radial distance between the circumferential base 1 and the focusing ring 201 meets the requirements, the measuring light shines on the portion of the base 30 between the base 1 and the focusing ring 201, that is, the measuring distance is equal to the preset distance threshold, and the green light of the laser sensor 21 lights up. When the radial distance between the circumferential base 1 and the focusing ring 201 does not meet the requirements, the measuring light shines on the focusing ring 201 at least partially, that is, the measuring distance is less than the preset distance threshold, and the red light of the laser sensor 21 lights up.
[0041] Furthermore, by way of example, the preset distance threshold can also be the distance between the laser sensor 21 and the focusing ring 201. When the radial distance between the circumferential base 1 and the focusing ring 201 meets the requirements, the measuring light shines on the base 30 portion between the base 1 and the focusing ring 201, that is, the measuring distance is greater than the preset distance threshold. At this time, the green light of the laser sensor 21 lights up. When the radial distance between the circumferential base 1 and the focusing ring 201 does not meet the requirements, the measuring light shines on the focusing ring 201 at least partially, that is, the measuring distance is equal to the preset distance threshold. At this time, the red light of the laser sensor 21 lights up.
[0042] For example, in the above-described measurement of the second distance D2, the preset distance threshold can be the distance between the laser sensor 21 and the cover ring 202. When the radial distance between the circumferential base 1 and the cover ring 202 meets the requirements, the measuring light illuminates the base 30 portion and the focusing ring 201 portion between the base 1 and the cover ring 202, that is, the measuring distance is greater than the preset distance threshold. At this time, the green light of the laser sensor 21 lights up. When the radial distance between the circumferential base 1 and the cover ring 202 does not meet the requirements, the measuring light illuminates at least partially on the cover ring 202, that is, the measuring distance is equal to the preset distance threshold. At this time, the red light of the laser sensor 21 lights up.
[0043] In some embodiments, reference Figure 1 As shown, the measuring component 2 may include a support frame 22 rotatably connected to the base 1, and a laser sensor 21 connected to the support frame 22, enabling it to move circumferentially around the axis of the base 1. The measuring light emitted by the laser sensor 21 is parallel to the axis of the base 1. Thus, by rotating the support frame 22, the laser sensor 21 can be driven to move circumferentially around the axis of the base 1 for circumferential measurement of the first distance D1 and the second distance D2, ensuring that the first distance D1 and the second distance D2 meet the actual usage requirements.
[0044] It is understood that the support frame 22 can be constructed in any suitable manner; in some embodiments, reference is made to... Figure 1As shown, the support frame 22 may include a first support rod 221 and a second support rod 222. The first support rod 221 is adapted to be connected to the base 1, and the second support rod 222 is connected to the first support rod 221 and used to mount the laser sensor 21. Thus, the laser sensor 21 can be exemplarily connected below the second support rod 222, that is, on the side of the second support rod 222 closer to the base 1. Of course, the laser sensor 21 can also be connected to any suitable position, such as the end of the second support rod 222 away from the first support rod 221. This disclosure is not limited thereto.
[0045] Furthermore, the first support rod 221 and the second support rod 222 can be constructed as square rods or round rods, etc., and this disclosure does not specifically limit them.
[0046] In some embodiments, reference Figure 1 As shown, the first support rod 221 is rotatably connected to the base 1, or the second support rod 222 is rotatably connected to the first support rod 221. Thus, the laser sensor 21 can achieve circumferential movement around the axis of the base 1 through either of these methods. For example, the first support rod 221 can be connected to the base 1 via a bearing, with the first support rod 221 connected to the inner ring of the bearing. The base 1 has a groove for mounting the bearing, and the outer ring of the bearing is connected to the inner wall of the groove. Similarly, the first support rod 221 can also be rotatably connected to the second support rod 222 via a bearing, with the first support rod 221 connected to the inner ring of the bearing and the second support rod 222 connected to the outer ring of the bearing. This disclosure does not impose specific limitations in this regard.
[0047] Furthermore, in some other possible alternative embodiments not shown in the accompanying drawings, the support frame 22 may also include a support rod and a support plate, wherein the laser sensor 21 may be connected to the lower part of the support plate, i.e., the side of the support plate closer to the base 1, and a slide rail is provided on the support plate for the laser sensor 21 to slide circumferentially around the axis of the base 1. This disclosure is not limited thereto.
[0048] In some embodiments, reference Figure 1 As shown, the axis of the first support rod 221 can be parallel to the axis of the base 1, and / or the axis of the second support rod 222 can be perpendicular to the axis of the base 1. This arrangement reduces the space occupied by the support frame 22. In this exemplary embodiment, the first support rod 221 is set with its axis parallel to the axis of the base 1, and the second support rod 222 is set with its axis perpendicular to the axis of the base 1. This perpendicular arrangement of the first and second support rods facilitates the installation of the laser sensor 21 and also allows for easy adjustment and determination of the direction of the measuring light.
[0049] For example, the upper surface of the base 1 can be set to be horizontal, the first support rod 221 is perpendicular to the upper surface of the base 1, and the second support rod 222 is set to be horizontal. Therefore, the laser sensor 21 is connected to the lower part of the second support rod 222. At this time, the measuring light emitted by the laser sensor 21 is perpendicular to the upper surface of the base 1, that is, parallel to the axis of the base 1, which facilitates the measurement of the first distance D1 and the second distance D2.
[0050] In some embodiments, reference Figure 1 As shown, a level 3 can be installed on the second support rod 222. In this way, when the upper surface of the base 1 is horizontal, the level 3 can be used to detect the second support rod 222 to ensure that the axis of the second support rod 222 is perpendicular to the axis of the base 1, thereby ensuring that the measuring light emitted by the laser sensor 21 is parallel to the axis of the base 1, so as to facilitate the measurement of the first distance D1 and the second distance D2.
[0051] Furthermore, in some embodiments, references Figure 1 As shown, the measuring component 2 may further include a controller 23, which is adapted to adjust the diameter of the measuring light emitted by the laser sensor 21. The controller 23 can adjust the diameter of the measuring light by changing the focal length of the lens of the laser sensor 21 (e.g., using an adjustable-focus lens or replacing the lens with one of different focal lengths), or by inserting a variable aperture stop in the optical path to mechanically limit the diameter of the measuring light, or by using a diffraction element (e.g., a hologram) to shape the measuring light to generate a measuring light of a specific shape or size. This disclosure is not limited thereto.
[0052] The controller 23 can be, for example, a computer, which can dynamically calculate and adjust the diameter of the measuring light through a built-in algorithm. The user only needs to input the target distance or diameter in the software, and the laser sensor 21 can automatically complete the calibration.
[0053] In some embodiments, the distance between the laser sensor 21 and the first support rod 221 can be adjusted. This allows for the switching detection of a first distance D1 and a second distance D2. It is understood that the axes of the measuring rays emitted by the laser sensor 21 are different when measuring the first distance D1 and the second distance D2. Exemplarily, the second support rod 222 is lockably slidably connected to the first support rod 221. For example, a self-locking track-slider structure can be provided between the first support rod 221 and the second support rod 222, wherein the track is connected to the first support rod 221, and the second support rod 222 is connected to the slider to be lockably movable relative to the first support rod 221, for adjusting the distance between the laser sensor 21 and the first support rod 221.
[0054] In some other embodiments, the length of the second support rod 222 may be adjustable. For example, the second support rod 222 may be constructed as a cylinder, wherein the cylinder body is connected to the first support rod 221, and the laser sensor 21 is connected to the piston rod of the cylinder. The piston rod may be adjusted in extension length to adjust the distance between the laser sensor 21 and the first support rod 221.
[0055] In some embodiments, reference Figure 1 As shown, a distance sensor 4 can be disposed between the first support rod 221 and the second support rod 222, and / or, a distance sensor 4 can be disposed between the laser sensor 21 and the first support rod 221. Thus, by distributing the distance sensor 4, the position of the laser sensor 21 can be monitored to ensure that the laser sensor 21 is positioned above a location suitable for measuring the first distance D1 and the second distance D2, so that a measuring light beam can be emitted to measure the first distance D1 and the second distance D2. Specifically, the radial dimension of the measuring light beam is equal to the first distance D1 or the second distance D2, and the center of the measuring light beam is the same as the center of the radial distance D1 or the second distance D2.
[0056] The distance sensor 4 can be an ultrasonic sensor, an infrared ranging sensor, or a laser sensor, etc., and this disclosure does not make any specific limitations on it.
[0057] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0058] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0059] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.
Claims
1. A measuring device for an etching machine, the etching machine comprising a focusing ring assembly and a base, characterized in that, The measuring device comprises: a base connected to the pedestal; and a measuring assembly connected to the base, comprising a laser sensor adapted to be disposed above the base and the focus ring assembly, the laser sensor being used to measure the radial distance between the base and the focus ring assembly in a non-contact manner.
2. The measuring device of claim 1, wherein, The focus ring assembly comprises a focus ring and a cover ring, the measuring assembly being used to detect a first distance between the outer edge of the base and the inner edge of the focus ring, and / or a second distance between the outer edge of the base and the inner edge of the cover ring.
3. The measuring device of claim 2, wherein, The measuring assembly comprises a support frame rotatably connected to the base, the laser sensor being connected to the support frame to enable circumferential movement around the axis of the base, the measuring light emitted by the laser sensor being parallel to the axis of the base.
4. The measuring device of claim 3, wherein, The support frame comprises a first support rod adapted to be connected to the base and a second support rod connected to the first support rod and used to mount the laser sensor.
5. The measuring device of claim 4, wherein, The first support rod is rotatably connected to the base, or the second support rod is rotatably connected to the first support rod.
6. The measuring device of claim 4, wherein, The axis of the first support rod is parallel to the axis of the base, and / or the axis of the second support rod is perpendicular to the axis of the base.
7. The measuring device of claim 5, wherein, A level is disposed on the second support rod; and / or, The measuring assembly further comprises a controller adapted to adjust the diameter of the measuring light emitted by the laser sensor.
8. The measuring device of claim 7, wherein, The second support rod is lockably and slidably connected to the first support rod, and / or the length of the second support rod is adjustable to adjust the distance between the laser sensor and the first support rod.
9. The measuring device of claim 8, wherein, A distance sensor is disposed between the first support rod and the second support rod, and / or a distance sensor is disposed between the laser sensor and the first support rod.
10. The measuring device according to any one of claims 1 to 9, characterized in that The radial dimension of the base is equal to that of the wafer.