Wafer for measurement, gap measuring device, and measurement system

Abstract

The application relates to a wafer for measurement, a gap measurement device and a measurement system. The wafer is provided with one or more groups of recesses near the edge of the wafer, which make the detection light path pass through or reflect. The application adopts the method of providing the wafer with recesses, which make the detection light path pass through or reflect, so that the wafer can be used as a wafer focusing ring gap measurement. The incident light emitted by the light assembly of the gap measurement device can pass through or reflect through the recesses, and then is reflected on the measured object such as a focusing ring, so that the photoelectric detector can collect the reflected light signal, and then the gap measurement system can calculate the lateral distance between the edge of the wafer and the measured object, thereby avoiding the problem that the height of the measured object is too low to form reflected light, that is, the distance measurement cannot be completed.

Description

Technical Field

[0001] This application relates to the field of semiconductor equipment testing, specifically to a wafer for measurement, a gap measuring device and a measuring system, which can be used to measure the gap between the wafer edge and the focusing ring. Background Technology

[0002] In advanced semiconductor integrated circuit manufacturing, hundreds of wafer processing steps are involved. Wafers need to be transferred between various process cavities, such as thin film deposition cavities, etching cavities, and cleaning cavities. Wafers are typically secured by a robotic arm within a focus ring on an electrostatic chuck. The accuracy of the wafer's placement within the focus ring significantly impacts subsequent processing. For example, during plasma etching, uneven gaps between the wafer and the focus ring can lead to uneven electric field distribution, easily causing arcing and damaging both the wafer and the focus ring, or even destroying the electrostatic chuck. In chemical / physical vapor deposition, if the wafer is not placed in the preset position or is tilted, the deposited film thickness will be uneven, affecting device performance. In photolithography, the accuracy of wafer positioning directly determines the success or failure of the lithography process.

[0003] Currently, wafer positioning methods typically employ optical methods. For example, CN114812419A discloses a wafer focusing ring gap measurement device, which includes a wafer and a gap measurement module mounted on the wafer. The gap measurement module emits light towards the focusing ring through a light source, and a drive module can move the measurement module radially across the wafer to adjust the focal spot position. When the focal spot is precisely on the focusing ring, the reflected light signal exhibits an extreme value. Therefore, the width of the gap between the wafer and the focusing ring can be derived from the step size and initial position of the drive module, enabling in-situ measurement of the wafer-focusing ring gap. This eliminates the need for a calibration positioning cavity, saving space, and allows for real-time in-situ detection.

[0004] With the development of semiconductor manufacturing processes, the initial height of the focusing ring has become increasingly lower, which is a current state and development path of semiconductor manufacturing processes. For example, in commonly used equipment today, there are actual operating conditions where the focusing ring is only 0.775mm higher than the measuring wafer, meaning that from a cross-sectional perspective, the height difference between the upper surface of the focusing ring and the upper surface of the measuring wafer is only 0.775mm.

[0005] Due to the limited height of the focusing ring, there is a technical problem that the focal spot cannot be projected onto the focusing ring, which means that the extreme value of the reflected light signal cannot be obtained. As a result, the existing measurement methods cannot measure the lateral gap between the focusing ring and the wafer.

[0006] To address the problems with existing measurement devices, there is a need for a new wafer, as well as a device and system for addressing the gap between the focusing ring and the wafer edge. Utility Model Content

[0007] The technical problem to be solved by this application is to provide a wafer for measurement, a gap measuring device and a gap measuring system, which can be used to measure the gap between the wafer edge and the focusing ring, and is not affected by the height of the focusing ring.

[0008] According to a first aspect of the present application, a measuring wafer is provided, wherein one or more sets of recesses are provided near the edge of the wafer to allow the detection optical path to pass through or reflect.

[0009] In one embodiment, the recess is formed by the upper surface of the wafer sinking towards the lower surface of the wafer.

[0010] In one embodiment, the wafer comprises at least any one of the following: - The recess is ring-shaped, and the center of the ring is concentric with the center of the wafer; - When there are multiple sets of the depressions, they are evenly distributed on the wafer; -The wafer surface at the recess is an arc surface, a curved surface, or a smooth slope; - The depth of the recess is less than the thickness of the wafer.

[0011] In one embodiment, the wafer is frustum-shaped, and the peripheral sidewalls of the wafer serve as the recess.

[0012] In one embodiment, the depth of the depression is between 0.1 mm and 0.35 mm.

[0013] In one embodiment, the width of the recess is between 1 mm and 6 mm.

[0014] According to a second aspect of the embodiments of this application, a gap measuring device is provided, comprising: Wafers as described in any of the preceding items; An optical component, disposed on the wafer, is used to emit incident light to the object under test, and to reflect a portion of the incident light onto the object under test via the recess. A photodetector is used to collect the light signal reflected by the object being measured.

[0015] In one embodiment, at least one of the optical component and the photodetector is fixed to the surface of the wafer; or, the optical component is fixed within a groove on the wafer.

[0016] In one embodiment, the optical component includes at least: a light source for emitting incident light to the object under test; and an optical element disposed in the optical path of the incident light for forming a linear light spot at the projection position of the incident light on the object under test.

[0017] In one embodiment, the optical element includes at least one of the following elements: a cylindrical lens, a flat cylindrical lens, a Powell prism, a cylindrical lens array, a flat cylindrical lens array, and a diffractive optical element.

[0018] In one embodiment, the optical assembly further includes a beam splitter disposed between the light source and the optical element, the beam splitter being used to split the incident light into two sub-beams separated by a set divergence angle, forming two linear and parallel sub-spots at the projection position.

[0019] In one embodiment, the light source is at least two light emitters, each emitting light that is separated from each other by a set divergence angle, forming at least two linear and parallel sub-spots at the projection position.

[0020] In one embodiment, the optical assembly further includes a rotation module for driving the optical element to rotate. The rotation module is used to control the optical element to rotate to a first angle so that the incident light irradiates the projection position to form a linear light spot; and to control the optical element to rotate to a preset angle to reach a second angle so that the linear light spot moves a certain distance at the projection position accordingly.

[0021] In one embodiment, the light source is composed of any one of the following components: -A light source; - A light source and an optical fiber connected to the light source, the optical fiber being used at least to transmit the incident light to the outside; - A light source, an optical fiber connected to the light source and a lens connected to the optical fiber, the optical fiber and the lens being used at least to transmit the incident light to the outside.

[0022] In one embodiment, the photodetector is a position-sensitive detector, a linear CCD array, or a CMOS linear array sensor.

[0023] According to a third aspect of the embodiments of this application, a gap measurement system is provided, including an information processing component and a gap measurement device as described in any of the preceding claims. The information processing component includes a microcontroller, a transmission module, and a processor. The microcontroller is electrically connected to the photodetector and is communicatively connected to the processor through the transmission module.

[0024] Compared with the prior art, the beneficial effects of this application are as follows: This application employs a recess on a wafer that allows the detection optical path to pass through or reflect, thereby enabling the wafer to be used as a workpiece for measuring the wafer focusing ring gap. Even if the focusing ring is very low, the incident light emitted by the optical component of this application can pass through the recess or be reflected, and then irradiate the object under test, such as the focusing ring, and be reflected, so that the photodetector can collect the reflected light signal. Then the gap measurement system can use the reflected light signal to calculate the lateral distance between the wafer edge and the object under test, avoiding the problem that the distance measurement cannot be completed because the height of the object under test is too low to form reflected light. Even if the height difference between the upper surface of the focusing ring and the upper surface of the wafer is less than 0.5 mm, or even if the upper surface of the focusing ring is basically flush with the upper surface of the wafer when the wafer is placed in place, the incident light emitted by the optical component of this application is partially reflected by the concave section, and the remaining part is directly incident on the focusing ring from above the upper surface of the wafer, so that the light spot formed by the optical component can be presented on the focusing ring, and then the photodetector can collect the reflected light for distance calculation through the light signal of the reflected light; This application integrates optical components and photodetectors onto a wafer, which can be identical in shape and size to the wafer. This allows for in-situ measurement of the gap between the wafer and the focusing ring, eliminating the need for a calibration positioning cavity, saving space, and enabling real-time in-situ detection. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating a wafer according to an exemplary embodiment; Figure 2 This is a schematic diagram of a wafer according to another exemplary embodiment; Figure 3 This is a schematic cross-sectional view of a wafer according to an exemplary embodiment; Figure 4 This is a schematic diagram of an optical path on a wafer according to an exemplary embodiment; Figure 5 This is a schematic diagram of a gap measuring device according to an exemplary embodiment; Figure 6 This is a schematic diagram of the optical path emitted by the optical component in the gap measuring device; Figure 7 This is a measurement schematic diagram of a gap measuring device according to an exemplary embodiment; Figure 8 This is a measurement schematic diagram of a gap measuring device according to another exemplary embodiment; Figure 9 This is a schematic block diagram of a gap measurement system according to an exemplary embodiment.

[0026] In the diagram, 1 is the focusing ring; 2 is the wafer; 3 is the optical component; 4 is the photodetector; and 20 is the recess. 21, upper surface of the wafer; 22, peripheral sidewall; 23, lower surface of the wafer; 31, light source component; 32, First optical element; 5, Information processing component; 51, Microcontroller; 52, Transmission module; 6. Processor; 201. First recess; 202. Second recess; 203. Third recess; 204, fourth recess; 301, light source; 302, second optical element. Detailed Implementation

[0027] Unless otherwise defined, the technical or scientific terms used in this specification and claims shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. Specific embodiments of this application will be described below in conjunction with the accompanying drawings. It should be noted that, in order to provide a concise description, this specification cannot exhaustively describe all features of the actual embodiments. Without departing from the spirit and scope of this application, those skilled in the art can modify and substitute the embodiments of this application, and the resulting embodiments are also within the protection scope of this application.

[0028] Currently, the gap measurement module emits light from a light source towards the focusing ring. A drive module then moves the measurement module radially across the wafer, adjusting the focal spot position to measure the distance between the wafer edge and the focusing ring. The focal spot is positioned precisely on the focusing ring, and its location is typically identified by light intensity. The center point of the spot is determined based on its intensity parameters, thus obtaining an image of the spot. However, when the focusing ring is relatively small, such as when the distance between the upper surface of the focusing ring and the upper surface of the wafer is less than or equal to 0.775 mm, the focal spot cannot be projected onto the focusing ring regardless of adjustments. Instead, it is projected above the focusing ring, preventing the gap measurement device from receiving the reflected light signal and thus hindering in-situ measurement of the gap between the wafer and the focusing ring.

[0029] To address the aforementioned technical problems, this application provides a wafer for measurement, such as... Figure 1 , Figure 2 As shown, the wafer 2 has one or more sets of recesses 20 near its edge for the passage or reflection of the detection light path. In this embodiment, the recesses 20 create physical space for the detection light path to illuminate the object under test, such as a focusing ring. When the upper surface of the wafer is flush with the upper surface of the focusing ring, the detection light path can still be irradiated from the wafer through the recesses onto the focusing ring because the recesses 20 serve as light guides. The reflected light signal can then be detected, enabling the wafer to be used as a workpiece for gap measurement.

[0030] like Figure 4 As shown, during the wafer focusing ring gap measurement process, it is assumed that the upper surface of the focusing ring 1 is flush or nearly flush with the upper surface of the wafer 2, that is, when the wafer 2 is placed on the electrostatic chuck, there is no height difference or the height difference is close to 0 between the upper surface of the wafer 2 and the upper surface of the focusing ring 1, for example, the height difference is only 0.1 mm. By creating a recess 20 downward on the upper surface of the wafer 2, one or more sets of recesses 20 appear on the side of the wafer 2 close to the focusing ring 1. The incident light emitted by the optical component 3 is partially incident on the recesses 20 through the angle setting, and then reflected onto the focusing ring 1, thereby forming a light spot on the focusing ring 1 that can be reflected for detection, thereby achieving the technical objective of this application.

[0031] like Figure 1 and Figure 3 As shown, the recess 20 is formed by sinking from the upper surface 21 to the lower surface 23 of the wafer. In one embodiment, the depth h of the recess 20 is less than the thickness D of the wafer, that is, the recess 20 is groove-shaped and not a hole penetrating the wafer 2. In the radial direction of the wafer 2, see... Figure 3 As shown, the depth h of the depression 20 is inconsistent; it may first increase and then decrease, or, see... Figure 4 As shown, the depth of the recess varies, resembling a wave. The wafer surface at the recess 20 is curved, allowing for multi-level reflection of the detection light path, further ensuring that the detection light illuminates the focusing ring 1. The wafer surface at the recess 20 can also be arc-shaped, such as a bowl shape, or a smooth slope. The wafer surface at the recess 20 can also be three-dimensionally designed according to the needs of the detection light path, making it easier to reflect the detection light and guide it to the object being detected, such as the focusing ring; these variations are all within the scope of protection of this application.

[0032] Recess 20 is located at the edge of the wafer, specifically in the radial direction of the wafer, see... Figure 2 , Figure 3 and Figure 4 As shown, the recess 20 penetrates the edge of the wafer, meaning that the thickness at the edge of the wafer is lower than the thickness D of the wafer. In this embodiment, the diameter of the lower surface of the wafer 2 is consistent with the wafer diameter required in the semiconductor process, which facilitates the measurement of the wafer focusing ring gap and facilitates the use of the measurement data to complete the wafer transfer and positioning after the measurement is completed.

[0033] The recesses 20 can be in one or more groups, and their number is unlimited. They can be set according to actual measurement needs, such as three, four, or more groups. When there are multiple groups of recesses 20, they can be evenly distributed on the wafer 2 or discretely and non-uniformly distributed, depending on actual measurement needs. The position and distribution of the recesses 20 are not limited here. The recesses 20 are annular, and the center of the annulus is concentric with the center of the wafer. That is, the recess is a groove or a slope near the edge of the wafer. Specifically, the wafer surface at the recess 20 is an arc surface, a curved surface, or a smooth slope.

[0034] like Figure 2 In the illustrated embodiment, wafer 2 is frustum-shaped, and the peripheral sidewall 22 of wafer 2 serves as a recess. It can be understood that the outer edge of the upper surface of wafer 2 is cut off by a plane to form a ramp, making the diameter of the upper surface 21 of the wafer smaller than the diameter of the lower surface 23 of the wafer. The peripheral sidewall 22 formed by the ramp serves as a recess, allowing the detection light path to illuminate the focusing ring 1 through the peripheral sidewall 22. Specifically, wafer 2 can be frustum-shaped in the thickness direction, i.e., the cutting plane extends from the upper surface of the wafer to the lower surface of the wafer; or, wafer 2 can be a combination of frustum and cylinder, i.e., a portion of wafer 2 is cut off by a plane in the thickness direction, and the remaining portion is not cut off and appears as a thinner cylinder.

[0035] This application also provides a gap measuring device, with reference to... Figures 4 to 8 As shown, in one specific embodiment, it includes: Wafer 2 can be any of the wafers described in the above embodiments, see Figures 1 to 4 As shown, it has a recess 20 that extends from the upper surface of the wafer to the lower surface of the wafer (e.g., Figure 5 The first depression 201, the second depression 202, the third depression 203, and the fourth depression 204 are located in the middle. The optical component 3 is disposed on the wafer 2 and is used to emit incident light to the object under test (such as the focusing ring 1), and to reflect part of the incident light onto the object under test through the concave. Photodetector 4 is used to collect the light signal reflected by the object being measured.

[0036] This application employs a recess on the wafer 2. Incident light emitted from the optical component 3 is reflected by the recess and then illuminates the object under test, such as the focusing ring 1, and is reflected back. The photodetector 4 can then collect the reflected light signal, which can be used to calculate the gap between the focusing ring and the wafer edge. This allows the gap measurement system to use the reflected light signal collected by the photodetector 4 to calculate the lateral distance between the wafer edge and the object under test, avoiding the problem of insufficient light reflection due to the low height of the object under test, thus preventing gap measurement.

[0037] In one embodiment, the optical component 3 is used to form a linear light spot S of the incident light. The linear light spot S is the focal line of the incident light, which can be understood as a one-dimensional extended focused light. That is, the linear light spot S has a certain length. In this application, the length direction of the linear light spot is consistent with the height direction of the focusing ring 1, so as to ensure that the incident light can be irradiated on the focusing ring 1 and then reflected, so that the photodetector 4 can collect the light signal of the linear light spot. This facilitates the subsequent calculation of the lateral distance between the wafer edge and the focusing ring 1 based on the light signal, avoiding the problem that the distance measurement cannot be completed because the height of the focusing ring 1 is too small to form reflected light.

[0038] This application can also construct a gap measurement device by integrating the optical component 3 and the photodetector 4 onto the wafer 2. The wafer is preferably a wafer with dimensions consistent with those processed during semiconductor manufacturing. Placing it at the wafer pre-processing position enables in-situ detection and acquisition of wafer position information. In a preferred embodiment, in... Figure 5 In this embodiment, the sheet-like structure beneath the aforementioned optical component is the wafer described in this application. In another variation, the wafer may be replaced by an object with the same appearance as the wafer, and the gap measuring device may be integrated into this object.

[0039] More specifically, refer to Figure 5 In the illustrated embodiment, the recess 20 is preferably an inverted hemispherical shape that does not penetrate the edge of the wafer, similar to a pit formed by a raindrop hitting the ground. It is preferably not penetrated by the edge of the wafer. Figure 5 The diagram illustrates the positional relationship between the second recess 202 and the edge of the wafer. In a variation, the recess 20 can be connected to the edge of the wafer, meaning the recess directly connects to the edge of the wafer, for example... Figure 6 The appearance of the depression shown is within the protection scope of this utility model. Furthermore, those skilled in the art will understand that the depth, width, and other dimensions of the depression can be within a certain proportional range. For example, preferably, the depth of the depression is between 0.1 mm and 0.35 mm, and the width of the depression is between 1 mm and 6 mm, etc. These variations are also within the protection scope of this utility model.

[0040] In one specific embodiment, such as Figure 4 , Figure 6As shown, the incident light emitted by the aforementioned optical component 3 is configured such that at least a portion of the beam directly strikes the wafer 2. The optical component 3 can adjust the angle of the incident light emitted or the position of the exit port to ensure that a portion of the incident light strikes the upper surface of the wafer 2, while the remaining portion strikes the focusing ring 1. Furthermore, the incident light forms a linear focal line, or linear spot, in the focal plane. This linear spot has a certain length, ensuring that it appears on the focusing ring. Even if the height difference between the upper surface of the focusing ring and the upper surface of the wafer is less than 0.5 mm, in this embodiment, at least a portion of the incident light emitted by the optical component extends close to the upper surface of the wafer, while the remaining portion strikes the wafer. This allows the linear spot formed by the optical component to appear on the focusing ring, enabling the information processing component to acquire measurement information from the linear spot.

[0041] In one specific embodiment, such as Figure 6 As shown, the aforementioned optical component 3 includes at least: a light source 31 for emitting incident light to the focusing ring 1; a first optical element 32 disposed in the optical path of the incident light for forming a linear light spot S on the focusing ring 1; and a photodetector 4 for receiving reflected light returning from the focusing ring 1. Since the lateral distance G between the wafer edge and the focusing ring 1 (i.e., the gap width between wafer focusing rings) is unknown, it is understood that the lateral direction in this specification refers to the horizontal direction, i.e., the radial direction of the wafer. The linear light spot S formed by the incident light is reflected on the focusing ring 1 and received by the photodetector 33, thereby acquiring measurement information of the linear light spot, such as light intensity information. Based on the light intensity information, the distance between the light source and the focusing ring is calculated, and then the distance G is calculated. In this embodiment, the first optical element 32 shapes or converts the light emitted from the light source 31, making the incident light emitted by the optical component 3 form a straight spot within its focal plane. This spot can be understood as having a certain length, causing the incident light to appear as a strip-shaped linear spot on the focusing ring 1. The length direction of this linear spot is the height direction of the focusing ring, thus ensuring that the incident light can be reflected by the focusing ring 1. Even if the height difference between the upper surface of the focusing ring 1 and the upper surface of the wafer is small, part of the linear spot is still visible on the focusing ring. Compared to the dot-shaped spot in the prior art, the linear spot is easier to illuminate the focusing ring and is better collected by the information processing component 4, enabling the measurement of the lateral distance between the wafer and the focusing ring.

[0042] like Figure 6In the illustrated embodiment, the wafer 2 has a first recess 201 that extends from the upper surface of the wafer to the lower surface of the wafer, and the first recess 201 is located on the side of the wafer 2 near the focusing ring 1. In this embodiment, by providing the recess 201 on the side of the wafer 2 near the focusing ring 1, the incident light emitted from the optical component can be directed onto the focusing ring 1 through the recess 201. Furthermore, the upper surface of the focusing ring 1 is substantially flush with the upper surface of the wafer 2. This can be understood as follows: when the wafer is positioned in place, i.e., within the focusing ring, the thickness of the wafer (i.e., the height between the upper and lower surfaces of the wafer) ensures that there is no height difference between the upper surface of the wafer and the upper surface of the focusing ring, or the height difference is extremely small, close to 0. In this embodiment, a recess is formed on the outer side of the upper surface of the wafer 2, thereby creating a certain height difference between the upper surface of the recess and the upper surface of the focusing ring 1. This creates physical space for the incident light to illuminate the focusing ring 1, ensuring that the linear light spot is presented and reflected on the focusing ring 1. This recess can be formed by planar cutting or by other methods, which are not limited here.

[0043] Specifically, the recess can be any of the wafers disclosed in any of the above embodiments. The thickness of the wafer at the recess can be uniform, that is, the depth of the recess is uniform; or, the thickness of the wafer at the recess can be inconsistent, that is, the depth of the recess is inconsistent. For example, if the recess is an inclined slope, the thickness of the wafer in the inclined direction can gradually decrease or increase from the center of the wafer to the outside of the wafer. This is not limited, as long as it can reflect the incident light to the focusing ring; or, the recess can be a groove or a bowl shape, that is, the thickness of the wafer is lowest at the center of the recess, and the thickness of the wafer increases from the center of the recess to the edge of the recess. This is not limited. For example, the first recess 201 can be elliptical and have an inclined slope, and the thickness of the wafer can gradually decrease from the center of the wafer to the outside of the wafer in the inclined direction; the second recess 202 can be a semi-circular groove, and the depth of the second recess 202 can be inconsistent, such as being deeper on the side away from the focusing ring; the third recess 203 can be formed directly by planar cutting, and can be a regular rectangle; the third recess 204 can be formed by multiple small pits, and these pits can be the same or different in size and shape; such variations are all within the protection scope of this application.

[0044] In one embodiment, the light source 31 may be a laser diode or other single light source; the light source 31 may also include a light source and an optical fiber connected to the light source. The light source may be a laser, and its position may be arbitrarily set, not limited to being integrated on the wafer 2. The light can be transmitted to the first optical element 32 through the optical fiber; or, the light source 31 may also include a light source, an optical fiber connected to the light source, and a lens connected to the optical fiber. The lens may be used to shape or amplify the light transmitted from the optical fiber, so as to facilitate the transmission of the light to the first optical element 32 so that the first optical element 32 shapes the light into a linear light spot.

[0045] Specifically, the first optical element 32 may include at least one of the following elements: a cylindrical lens 32a, a flat cylindrical lens, a Powell prism 32b, a cylindrical lens array, a flat cylindrical lens array, and a diffractive optical element. In this embodiment, the light beam emitted from the light source 31 is shaped onto the focal plane to form a one-dimensional extended linear light spot S, replacing the point light spot in the prior art. The linear light spot S has a certain length, making it suitable for scenarios where the height of the focusing ring 1 is low. This ensures that there is a light spot when the focusing ring 1 is flush with the upper surface of the wafer 2 (such as a wafer), thereby forming reflected light that can be detected by the photodetector 4. When the linear light spot S is formed on the focusing ring 1, the photodetector 4 detects the extreme value of the light signal of the linear light spot.

[0046] The photodetector 4 includes at least one optical sensor array for receiving the reflected light from the linear light spot and focusing ring 1, and recording measurement information, which includes at least the light intensity information of the linear light spot. The photodetector 33 can be a position-sensitive detector (PSD), a linear CCD, or a CMOS linear sensor.

[0047] In another embodiment, such as Figure 7 , Figure 8 As shown, the optical component 3 includes a light source 301 and a second optical element 302. The light source 301 is used to emit a light beam with a set divergence angle towards the focusing ring 1. The second optical element 302 is used to project the light beam onto the focusing ring 1 and form a linear light spot at the projection position. The linear light spot includes two straight sub-spots s1 and s2, and the extension direction of each sub-spot s1 and s2 is the height direction of the focusing ring 1. The photodetector 4 can be an image acquisition device. The image acquisition device acquires image information at the projection position and can transmit the image information to the processor through the transmission module. The image information includes at least light intensity information. The measurement information of the linear light spot includes image information and the angle value of the divergence angle. The processor obtains the geometric information of the linear light spot based on the image information. The geometric information of the linear light spot includes the distance R between the two sub-spots. Combined with the divergence angle, the distance between the light source 3 and the focusing ring 1 is calculated, thereby obtaining the lateral distance G between the edge of the wafer (wafer) and the focusing ring 1.

[0048] In this embodiment, a light source 301 is placed on the wafer 2 to project a beam with a set divergence angle onto the focusing ring 1. The beam is then shaped or converted by a second optical element 302 to form a linear spot on the focusing ring 1. An image acquisition device receives image information at the projection position, including the linear spot and the image information of the part of the focusing ring 1 where the linear spot is located. The image information is then processed by a processor to obtain the geometric information on the focusing ring 1, including the position of the linear spot on the focusing ring 1, so as to obtain the distance R between each sub-spot in the linear spot. Using triangulation and combined with the divergence angle, the projection distance from the light source 301 to the focusing ring 1 is calculated. Combined with the horizontal position of the light source 301, the lateral distance between the wafer 2 and the focusing ring 1 can be further obtained.

[0049] Furthermore, Figure 7 As shown, the wafer 2 has a first recess 201 that sinks from the upper surface of the wafer to the lower surface of the wafer. After the second optical element 302 shapes or converts the light beam, the light beam is projected onto the focusing ring 1 through the recess 201. The recess 201 creates physical space for the light beam to irradiate the focusing ring 1, ensuring that each sub-spot is presented on the focusing ring 1 and is reflected.

[0050] Furthermore, referring to the above embodiments, those skilled in the art will understand that the recess is merely a depression below the upper surface of the wafer. In the preferred embodiment, the recess is not a hole penetrating the wafer, thereby allowing the wafer to retain its normal machinability for use in wafer fabrication processes. The depth of the recess is less than the thickness of the wafer, such as between 0.1 mm and 0.35 mm.

[0051] Further, in a preferred embodiment, the recess is an ellipse or semicircle, i.e., an ellipse with the larger end facing upwards. In another embodiment, the recess is a cube or cylinder, its size proportions sufficient to ensure that some incident light can be reflected from the bottom of the recess to the focusing ring. The width of the recess is between 1 mm and 6 mm. Those skilled in the art will understand that the above embodiments are all within the scope of protection of this application.

[0052] Further, in a preferred embodiment, the recess extends to the edge of the wafer, meaning the recess begins at the edge of the wafer. In another variation, the recess is located on the upper surface of the wafer but does not contact the edge of the wafer; that is, the recess does not extend to the edge of the wafer. Those skilled in the art will understand that the above embodiments are all within the scope of protection of this application.

[0053] According to a second aspect of the embodiments of this application, a gap measurement system is provided, such as... Figure 9As shown, it includes an information processing component 5 and a gap measuring device as described in any of the above embodiments. The information processing component 5 includes a microcontroller 51, a transmission module 52, and a processor 6. The microcontroller 51 is electrically connected to the photodetector 4, and the microcontroller 51 is communicatively connected to the processor 6 through the transmission module 52. Specifically, the microcontroller 51 can be connected to the light source 31 and the photodetector 4 to control the operation of the light source 31 and the photodetector 4 and to collect measurement information. The transmission module 52 is used to transmit the measurement information to the processor 6 through wireless or wired communication. The measurement information includes the light signal of the linear light spot S detected by the photodetector 4. The processor 6 calculates the lateral spacing G between the wafer edge and the focusing ring 1 based on the light signal.

[0054] In one embodiment, the microcontroller 51 is integrated with the photodetector 4, such as a CCD camera, which is both a photodetector 4 and a microcontroller 51.

[0055] Specifically, the transmission module 52 can be a wireless communication module (such as Bluetooth, ZigBee, Wi-Fi, etc.). The gap measuring device also includes a power supply unit, which supplies power to each power-consuming module in the gap measuring device (such as microcontroller 51, light source 31, and transmission module 52).

[0056] Before measuring the gap between wafer focusing rings, the gap measurement system of this embodiment includes the following steps: Step S101: Start the gap measuring device and the robot arm transfers the gap measuring device to the electrostatic chuck. In step S102, the processor (which may be a host computer) sends a wireless signal to notify the gap measuring device to start the measurement and wait for the test results. Step S103: After the gap measuring device completes the measurement, it wirelessly transmits the test results to the host computer. Step S104: Test completed. The robot arm retrieves the gap measuring device and shuts down.

[0057] Measuring the gap between wafer focusing rings specifically includes: Step S201: After starting the test, the program performs a self-test; In step S202, the incident light emitted by the light source 31 is transmitted through the first optical element 32, and the photodetector 4 receives the reflected light returned from the focusing ring 1, acquires the light signal intensity data of the reflected light, and sends it to the microcontroller 51. In step S203, the microcontroller 51 or processor 6 acquires the geometric information of the linear light spot based on the optical signal intensity data, and calculates the distance between the light source and the focusing ring, thereby obtaining the lateral spacing G between the wafer and the focusing ring 1. The optical signal intensity data can be converted into a light intensity distribution curve. The processor extracts the geometric information of the linear light spot based on the optical signal intensity data. The geometric information of the linear light spot can be understood as the edge position of the linear light spot. In this way, the wafer edge position and the position of the focusing ring can be obtained, and the lateral spacing G between the wafer and the focusing ring 1 can be calculated through trigonometric relationships.

[0058] The above step S203 can be completed by processor 6, which can be integrated on wafer 2 or set up independently, such as as a host computer. The function of the host computer can vary depending on the implementation method. For example, the host computer can be the control host in the wafer processing system, or it can be other auxiliary systems that cooperate with the control host, or it can be a host in the measurement device provided in this application, such as a computer or industrial control computer that receives, displays or processes wireless data of the gap between the wafer edge and the focusing ring. These variations are all within the protection scope of this application.

[0059] The above-mentioned gap measurement system adopts Figure 8 The gap measuring device of the illustrated embodiment may include the following measurement steps: Step S301: Place the light source 301 on the upper surface of the wafer 2, and establish a complete optical path connection between the light source 301 and the image acquisition device through the reflection of the focusing ring 1. Step S302: The light source 301 projects a light beam with a set divergence angle α onto the focusing ring 1 to form a linear light spot at the projection position on the surface of the focusing ring, which includes at least two parallel sub-spots, each sub-spot extending along the height of the focusing ring. Step S303: The image acquisition device receives image information at the projection position, including at least the light intensity information of the linear light spot and the light intensity information of the focusing ring; Step S304: Process the image information using the processor, and obtain the geometric information of the linear light spot based on the light intensity information, including at least the size between two parallel sub-spots, i.e. the distance R between each sub-spot; The processor calculates the projection distance, i.e. the lateral distance L between the light source 301 and the focusing ring 1, based on the distance R and the divergence angle a. Subtracting the initial distance of the light source (i.e. the distance between the light source and the edge of the wafer) gives the lateral spacing G between the edge of the wafer and the focusing ring 1.

[0060] The aforementioned light source 301 projects a light beam with a set divergence angle onto the focusing ring 1. This beam, such as a laser, can be selected from the wavelength spectrum of visible light, microwaves, infrared light, and ultraviolet light; no limitation is made here. The light source 301 can be a vertical-cavity surface-emitting laser (VCSEL), an edge-emitting laser diode (EELD), or an optical fiber connected to a light-emitting element, which can be a laser diode or a laser. The position of the light source 301 is not limited; it can be disposed on the wafer 2, or the light-emitting element can be disposed externally, with the light beam formed by light transmission through an optical fiber disposed on the wafer 2. The light beam projected by the light source 301 is shaped or converted by the second optical element 302 to form a linear spot on the focusing ring 1, which includes at least two parallel sub-spots. Typically, the distance between the two parallel sub-spots is proportionally amplified to the projection distance according to the set divergence angle α.

[0061] The aforementioned image acquisition device is used to receive light information returned from the projection position and acquire image information at the projection position, including at least the light intensity information at each point in the image. This can be achieved using a digital camera, or even a simple CCD or CMOS image sensor. The specific location of the image acquisition device is not limited, as long as it can capture the reflected light, including the aforementioned linear light spot and the focusing ring 1 at the location of the linear light spot, and record the image information. Ideally, the image acquisition device is also located on the wafer, near the optical component.

[0062] The image information acquired by the aforementioned image acquisition device is transmitted to the processor via the transmission module for processing. The processor performs operations such as filtering and binarization on the image information, extracts the center lines of the two bright lines (i.e., sub-spots), calculates the pixel distance between the two center lines in the image, i.e., the size between the two sub-spots, i.e., the spacing R, and then, combined with the divergence angle α, calculates the lateral distance L between the light source 230 and the focusing ring 1 through simple geometric calculations: L = (R / 2) × ctg(α / 2). Thus, subtracting the initial distance information of the light source from the lateral distance L—that is, the initial distance D between the position of the light source on the wafer and the edge of the wafer—gives the lateral spacing G between the edge of the wafer and the focusing ring 1, i.e., G = LD.

[0063] Related experiments show that the optimal setting of the divergence angle α is between 20 degrees and 45 degrees. At this angle, the resulting laser linear spot shape exhibits more uniform variation and a better rate of change with distance. This ensures that the linear spot does not experience localized deformation, thereby providing higher measurement accuracy.

[0064] Specifically, the second optical element 302 can be one of the following: a cylindrical lens, a planar cylindrical lens, a Powell prism, a cylindrical lens array, a planar cylindrical lens array, and a diffractive optical element (DOE), or a combination thereof. In this embodiment, the second optical element 302 is used to form a bright linear spot on the focal plane of the light beam emitted from the light source 301. More preferably, it can be used to convert a single light beam emitted from the light source into two bright, parallel straight linear spots, see [reference needed]. Figure 8 As shown, the second optical element 302 can be used to split and shape the beam to form the two sub-spots s1 and s2. At this time, the two sub-spots have an initial distance R0. After obtaining the distance R between the two sub-spots on the focusing ring 1 through image information, when calculating the lateral distance L between the light source and the focusing ring 1, the distance between the two sub-spots involved in the calculation should be R minus R0, that is, L=(R-R0 / 2)×ctg(a / 2).

[0065] To form two linear sub-spots and facilitate the acquisition of the distance R between the two sub-spots s1 and s2 in the image information, in one specific embodiment, the optical component 3 further includes a beam splitter placed between the light source and the second optical element. The beam splitter is used to split the light beam into two sub-beams separated by a set divergence angle, forming two sub-spots at the projection position. The geometric information of the linear spot includes the distance between the two sub-spots. In this embodiment, a beam splitter is used to split the single beam emitted from the light source into two paths, which are separated from each other by a set divergence angle α. This allows two parallel linear spots, namely the aforementioned sub-spots s1 and s2, to be formed on the focusing ring 1. Specifically, the beam splitter can be a beam splitting prism, or a combination of a beam splitting prism and two reflectors. The reflectors are used to adjust the distance between the two beams to make them parallel.

[0066] In another embodiment of forming the two sub-spots s1 and s2, the light source is at least two light emitters, see [link to previous embodiment]. Figure 7 The two light sources 301 shown each emit a light path that is separated from each other by a set divergence angle α. Each light path is shaped by the second optical element 302, forming at least two parallel and linear sub-spots at the projection position. The geometric information of the linear spots includes the distance between the sub-spots. In this embodiment, two light sources emit a beam of light, and after being shaped by the second optical element, the two beams can form two linear and parallel sub-spots on the focusing ring 1.

[0067] In another embodiment, the optical component further includes a rotation module for driving the second optical element to rotate. The rotation module controls the second optical element to rotate to a first angle, so that the light beam illuminates the projection position, forming a linear light spot; and controls the second optical element to rotate to a preset angle to a second angle, so that the linear light spot travels a certain distance at the projection position. The specific measurement steps of this embodiment include: controlling the second optical element to be at the first angle A, shaping the light emitted from the light source into a straight light spot, and projecting it onto the first position of the focusing ring 1, whereby the image acquisition device acquires the first image; controlling the rotation module to rotate by a preset angle Δα, at which point the second optical element is at the second angle A+Δα, and the same beam of light is refracted or reflected to form a straight light spot, which is then projected onto the second position of the focusing ring 1, whereby the image acquisition device acquires the second image; the processor extracts the centerline positions of the two straight light spots from the first image and the second image respectively, and calculates the offset distance of the two straight light spots in the image, that is, the distance traveled by the linear light spot at the projection position. Combined with the rotation angle Δα, the lateral distance L between the light source and the focusing ring 1 can be calculated using triangulation.

[0068] Specifically, the movable second optical element can be a mirror or a prism. The light beam emitted from the light source can first pass through a collimating and shaping optical element (such as a cylindrical lens, a flat cylindrical lens, or a Powell prism) to form the aforementioned straight light spot, and then illuminate the movable second optical element, thereby achieving the sequential formation of two straight light spots on the focusing ring 1. The rotating module can be driven by a rotary motor, a piezoelectric rotary table, or other similar device.

[0069] In the above embodiments, at least one of the optical component and the photodetector is fixed to the surface of the wafer, such as by attachment or bonding, which is not limited thereto. It is understood that the fixing method and position of the optical component and the information processing component may be the same or different; for example, one of the optical component and the information processing component may be fixed to the upper surface of the wafer, while the other is fixed to the outer peripheral surface of the wafer; or both may be fixed to the upper surface or the outer peripheral surface of the wafer. It is understood that there may be multiple optical components, such as two, three, or four, which may be evenly distributed on the wafer.

[0070] To better accommodate the low height of the focusing ring, preferably, the optical component is fixed within a groove on the wafer, and the wafer has an optical path communicating with the groove, which allows incident light to exit to the outside of the wafer. Understandably, the optical element in the optical component is the last element for incident light to exit the wafer. In one embodiment, only the optical element is placed within the groove, allowing light illuminating the focusing ring to exit from inside the wafer, further ensuring its reflection by the focusing ring. In one embodiment, the optical path can extend from the groove towards the outer periphery of the wafer, forming a channel or through-hole through the outer periphery of the wafer. In one embodiment, the information processing component can be disposed within the groove of the wafer, capable of acquiring the image at the projection position on the focusing ring.

[0071] In the above embodiments, the transmission module can be a wireless communication module (such as Bluetooth, ZigBee, Wi-Fi, etc.). The gap measuring device also includes a power supply unit, which supplies power to each power-consuming module in the gap measuring device.

[0072] In the above embodiments, the processor may be fixed on a wafer and connected to the information processing component; or, the processor may be an independently configured host computer and connected to the information processing component via wireless communication.

[0073] The above description of the embodiments is intended to enable those skilled in the art to understand and apply this application. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, this application is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A wafer for measurement, characterized in that, One or more sets of recesses are provided near the edge of the wafer to allow the detection light path to pass through or reflect.

2. The wafer as described in claim 1, characterized in that, The depression is formed by the upper surface of the wafer sinking down to the lower surface of the wafer.

3. The wafer as described in claim 1, characterized in that, Includes at least one of the following: - The recess is ring-shaped, and the center of the ring is concentric with the center of the wafer; - When there are multiple sets of the depressions, they are evenly distributed on the wafer; -The wafer surface at the recess is an arc surface, a curved surface, or a smooth slope; - The depth of the recess is less than the thickness of the wafer.

4. The wafer as described in claim 1, characterized in that, The wafer is frustum-shaped, and the peripheral sidewalls of the wafer serve as the recess.

5. The wafer as described in claim 1, characterized in that, The depth of the depression is between 0.1 mm and 0.35 mm.

6. The wafer according to claim 5, characterized in that, The width of the depression is between 1 mm and 6 mm.

7. A gap measuring device, comprising: The wafer as described in any one of claims 1 to 6, An optical component, disposed on the wafer, is used to emit incident light to the object under test, and to reflect a portion of the incident light onto the object under test via the recess. A photodetector is used to collect the light signal reflected by the object being measured.

8. The gap measuring device as described in claim 7, characterized in that, At least one of the optical component and the photodetector is fixed to the surface of the wafer; or, the optical component is fixed within a groove on the wafer.

9. The gap measuring device as described in claim 7, characterized in that, The optical component includes at least: A light source, used to emit incident light onto the object being measured; An optical element is disposed in the optical path of the incident light to form a linear light spot at the projection position of the incident light on the object being measured.

10. The gap measuring device as described in claim 7, characterized in that, The optical element includes at least one of the following elements: a cylindrical lens, a flat cylindrical lens, a Powell prism, a cylindrical lens array, a flat cylindrical lens array, and a diffractive optical element.

11. The gap measuring device as described in claim 9, characterized in that, The optical assembly also includes a beam splitter placed between the light source and the optical element. The beam splitter is used to split the incident light into two sub-beams separated by a set divergence angle, forming two linear and parallel sub-spots at the projection position.

12. The gap measuring device as described in claim 9, characterized in that, The light source consists of at least two light emitters, each emitting light that is separated from the others by a set divergence angle, forming at least two linear and parallel sub-spots at the projection position.

13. The gap measuring device as described in claim 9, characterized in that, The optical assembly also includes a rotation module for driving the optical element to rotate. The rotation module is used to control the optical element to rotate to a first angle so that the incident light irradiates the projection position to form a linear light spot; and to control the optical element to rotate to a preset angle to a second angle so that the linear light spot moves a certain distance at the projection position accordingly.

14. The gap measuring device as described in claim 9, characterized in that, The light source component is composed of any one of the following components: -A light source; - A light source and an optical fiber connected to the light source, the optical fiber being used at least to transmit the incident light outward; - A light source, an optical fiber connected to the light source, and a lens connected to the optical fiber, wherein the optical fiber and the lens are at least used to transmit the incident light outward.

15. The gap measuring device as described in claim 7, characterized in that, The photodetector is a position-sensitive detector, a linear CCD array, or a CMOS linear array sensor.

16. A gap measurement system, characterized in that, The device includes an information processing component and a gap measuring device as described in any one of claims 5 to 15. The information processing component includes a microcontroller, a transmission module, and a processor. The microcontroller is electrically connected to the photodetector and is communicatively connected to the processor through the transmission module.

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