Device and method for measuring gap between wafer edge and focus ring

Abstract

The invention relates to a device and method for measuring a gap between a wafer edge and a focusing ring, the device comprises a workpiece and is used for measuring the gap between the edge of the workpiece and the focusing ring, and at least the following devices are arranged on the workpiece: an optical assembly, which is used for emitting incident light to the focusing ring, the incident light forms a linear light spot on the focusing ring; and the information acquisition assembly is used for acquiring measurement information of the linear light spot and transmitting the measurement information to the processor, so that the processor can calculate the distance between the edge of the workpiece and the focusing ring in the transverse direction according to the measurement information. The method can be used for measuring the gap between the wafer edge and the focusing ring, and is not influenced by the height of the focusing ring.

Description

Technical Field

[0001] This application relates to the field of semiconductor equipment testing, specifically to a device and method for measuring the gap between a wafer edge and a 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, a new device is needed for the gap between the focusing ring and the wafer edge, along with a measurement method adapted to the aforementioned device. Summary of the Invention

[0007] The technical problem to be solved by this application is to provide a gap measuring device and a measuring method, 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 embodiments of this application, a gap measuring device is provided, which includes a workpiece and is used to measure the gap between the edge of the workpiece and a focusing ring, wherein the height difference between the upper surface of the focusing ring and the upper surface of the workpiece is not greater than 0.5 mm, and at least the following means are disposed on the workpiece: An optical component is used to emit incident light to the focusing ring and to form a linear light spot on the focusing ring. An information acquisition component is used to acquire measurement information of the linear light spot and transmit the measurement information to a processor, enabling the processor to calculate the lateral distance between the workpiece edge and the focusing ring based on the measurement information.

[0009] In one embodiment, the incident light emitted by the optical component is configured such that at least a portion of the beam is directly incident. On the workpiece.

[0010] In one embodiment, at least one of the optical component and the information acquisition component is fixed to the surface of the workpiece; or, the optical component is fixed within a groove of the workpiece.

[0011] In one embodiment, the workpiece has a recess that extends from the upper surface of the workpiece to the lower surface of the workpiece, and the recess is located on the side of the workpiece closer to the focusing ring.

[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] In one embodiment, the upper surface of the focusing ring is flush with the upper surface of the workpiece.

[0015] In one embodiment, the optical component includes at least: a light source for emitting incident light to the focusing ring; an optical element disposed in the optical path of the incident light for forming the linear light spot at the projection position of the focusing ring; and a photodetector for receiving reflected light returned from the focusing ring.

[0016] 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.

[0017] In one embodiment, the optical assembly further includes a beam splitter disposed 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, such that the measurement information includes the optical signal of the linear spot and the geometric information of the linear spot, the geometric information of the linear spot including the distance between the two sub-spots.

[0018] 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, such that the measurement information includes the light signal of the linear spot and the geometric information of the linear spot, the geometric information of the linear spot including the distance between the two sub-spots.

[0019] 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.

[0020] 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 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.

[0021] In one embodiment, the information acquisition component includes: a microcontroller connected to the light source and the photodetector, for at least controlling the operation of the light source and acquiring the measurement information; and a transmission module for transmitting the measurement information to a processor via wireless or wired communication; wherein the measurement information includes at least the optical signal of the linear light spot, and the processor calculates the lateral distance between the workpiece edge and the focusing ring based on the optical signal.

[0022] In one embodiment, the optical signal includes at least light intensity information. The processor obtains the geometric information of the linear light spot based on the light intensity information and calculates the distance between the light source and the focusing ring, thereby obtaining the lateral spacing between the measuring workpiece and the focusing ring.

[0023] In one embodiment, the optical signal further includes set divergence angle information. The processor calculates the distance between the light source and the focusing ring based on the geometric information and the divergence angle information, thereby obtaining the lateral spacing between the workpiece and the focusing ring.

[0024] In one embodiment, the processor is fixed to the workpiece and connected to the information acquisition component; or, the processor is a host computer and is connected to the information acquisition component via wireless communication.

[0025] According to a second aspect of the embodiments of this application, a method for measuring the gap between a wafer edge and a focusing ring is provided, employing the gap measuring device as described in any of the preceding claims, comprising: The optical component is controlled to emit incident light toward the focusing ring, and the incident light forms a linear spot on the focusing ring; Receive the reflected light signal returned by the focusing ring and acquire the measurement information of the linear light spot; The lateral distance between the workpiece edge and the focusing ring is calculated based on the measurement information.

[0026] In one embodiment, controlling the optical component to emit incident light toward the focusing ring includes: controlling the optical component to emit a beam of light with a divergence angle, and causing the beam of light to form a linear spot on the focusing ring, wherein the linear spot comprises two linear sub-spots, the method comprising: Image information on the focusing ring is acquired, and the image information contains the linear light spot; Based on the geometric information of the linear light spot and the divergence angle, the distance between the optical component and the focusing ring is calculated, thereby obtaining the lateral spacing between the workpiece and the focusing ring. The geometric information of the linear light spot includes the distance between two sub-spots.

[0027] In one embodiment, the incident light emitted by the optical component is configured such that at least a portion of the beam is directed directly onto the workpiece.

[0028] In one embodiment, the workpiece has a recess that extends from the upper surface of the workpiece to the lower surface of the workpiece, and the recess is located on the side of the workpiece closer to the focusing ring.

[0029] Compared with the prior art, the beneficial effects of this application are as follows: This application uses an optical component to form a linear light spot, which is the focal line of the incident light, i.e., a one-dimensional extended focused light. This ensures that the incident light can illuminate the focusing ring and be reflected, so that the information acquisition component can collect the measurement information of the linear light spot and calculate the lateral distance between the workpiece edge and the focusing ring. This avoids the problem that the distance measurement cannot be completed because the height of the focusing ring 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 workpiece is less than 0.5mm, or even if the upper surface of the focusing ring is flush with the upper surface of the workpiece, the incident light emitted by the optical component of this application is partly located on the upper surface of the workpiece, and the remaining part is directly incident on the focusing ring from above the upper surface of the workpiece, so that the linear light spot formed by the optical component can be displayed on the focusing ring, and then the information acquisition component can acquire the measurement information of the linear light spot. This application integrates optical components and information acquisition components onto a workpiece, 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

[0030] Figure 1 This is a schematic diagram of a gap measuring device according to an exemplary embodiment; Figure 2a , 2b This is a schematic diagram of the optical path emitted by the optical component in the gap measuring device; Figure 3 This is a measurement schematic diagram of a gap measuring device according to an exemplary embodiment; Figure 4 This is a schematic block diagram of a gap measuring device according to an exemplary embodiment; Figure 5 This is a measurement schematic diagram of a gap measuring device according to another exemplary embodiment; Figure 6 This is a measurement schematic diagram of a gap measuring device according to another exemplary embodiment.

[0031] In the diagram, 1 is the focusing ring; 2 is the workpiece; 3 is the optical component; 4 is the information acquisition component; and 31 is the light source component. 32, Optical element; 32a, Cylindrical lens; 32b, Powell prism; 33, Photodetector; 41, Microcontroller; 42, Transmission module; 5, Processor; 301, Light source; 302, Image acquisition device. Detailed Implementation

[0032] 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.

[0033] 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.

[0034] To address the aforementioned technical problems, this application provides a gap measuring device, with reference to... Figure 1 , Figure 2a , Figure 2b In one specific embodiment, it includes a workpiece 2 and is used to measure the gap between the edge of the workpiece and the focusing ring 1, wherein at least the following means are disposed on the workpiece 2: The optical component 3 is used to emit incident light to the focusing ring 1 and to form a linear light spot S on the focusing ring 1. Information acquisition component 4 is used to acquire measurement information of linear spot S and transmit the measurement information to the processor, so that the processor can calculate the horizontal distance between the workpiece edge and the focusing ring 1 based on the measurement information.

[0035] In this embodiment, the optical component 3 enables the incident light to form a linear light spot S, which is the focal line of the incident light. Specifically, it 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 illuminate the focusing ring 1 and be reflected. This allows the information acquisition component 4 to acquire the measurement information of the linear light spot, and then calculate the horizontal distance between the workpiece edge and the focusing ring 1, 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.

[0036] This application can also integrate the optical component 3 and the information acquisition component 4 onto the workpiece 2 to form a gap measuring device. The workpiece is preferably a wafer, with dimensions consistent with the wafers 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 1 In this embodiment, the sheet-like structure beneath the aforementioned optical component is the wafer described in this application. In another variation, the workpiece can be replaced by an object with the same appearance as the wafer, and the gap measuring device can be integrated into that object.

[0037] This application also provides a method for measuring the gap between the wafer edge and the focusing ring, using the gap measuring device described above, which may include the following steps: Step S1: The workpiece 2 (such as a wafer) with the aforementioned optical component 3 and information acquisition component 4 is placed on an electrostatic chuck by a robotic arm. Step S2: Control the optical component 3 to emit incident light to the focusing ring 1, and make the incident light form a linear light spot S on the focusing ring 1; Step S3: Receive the reflected light signal and acquire measurement information of the linear light spot; In step S4, the measurement information can be transmitted wirelessly or via wired transmission to the processor, which then calculates the lateral distance between the workpiece edge and the focusing ring based on the measurement information.

[0038] In one specific embodiment, such as Figure 2a , 2b As shown, the incident light emitted by the aforementioned optical component 3 is set to... A small portion of the light beam shines directly onto workpiece 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 hits the upper surface of workpiece 2, while the remaining portion can be positioned on 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 workpiece is less than 0.5 mm, in this embodiment, at least a portion of the incident light emitted from the optical component extends close to the upper surface of the workpiece, while the remaining portion hits the workpiece. This allows the linear spot formed by the optical component to appear on the focusing ring, enabling the information acquisition component to collect measurement information from the linear spot. Further extending from this embodiment, assuming the upper surface of the focusing ring is flush or substantially flush with the upper surface of the workpiece—that is, when the workpiece is placed on the electrostatic chuck, there is no height difference or the height difference between the upper surface of the workpiece and the upper surface of the focusing ring is close to zero, for example, a height difference of only 0.1 mm—a recess is created downwards on the upper surface of the workpiece, resulting in one or more sets of recesses on the side of the workpiece closest to the focusing ring. Incident light passes through a predetermined angle and strikes the recesses, then reflects back onto the focusing ring, thus forming a linear light spot on the focusing ring. This allows the information acquisition component to collect the light intensity information of the linear light spot, thereby achieving the technical objective of this invention. Further, in the above embodiment, the recess is located between the focusing ring and the optical component. Further, in embodiments with the aforementioned recess, the optical component can be fixed to the upper surface of the workpiece or fixed within a groove on the workpiece; such variations are all within the scope of protection of this invention.

[0039] In one specific embodiment, such as Figure 2a , 2b as well as Figure 3As shown, the aforementioned optical component 3 includes at least: a light source 31 for emitting incident light to the focusing ring 1; an 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 33 for receiving reflected light returning from the focusing ring 1. Since the lateral distance G between the workpiece 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 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 workpiece 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 acquired by the information acquisition component 4, enabling the measurement of the lateral distance between the workpiece and the focusing ring.

[0040] like Figure 3 and Figure 5In the illustrated embodiment, workpiece 2 has a recess 201 that extends from the upper surface of the workpiece to the lower surface of the workpiece, and the recess 201 is located on the side of workpiece 2 near the focusing ring 1. This embodiment, by providing the recess 201 on the side of workpiece 2 near the focusing ring 1, allows incident light emitted from the optical component to be projected 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 workpiece 2. This can be understood as follows: when the workpiece is positioned, i.e., within the focusing ring, the thickness of the workpiece (e.g., a wafer) (i.e., the height between the upper and lower surfaces of the workpiece) results in no height difference or a very small height difference between the upper surface of the workpiece and the upper surface of the focusing ring. This embodiment creates a recess 201 on the outer side of the upper surface of workpiece 2, thereby creating a certain height difference between the upper surface of the recess 201 and the upper surface of the focusing ring 1, providing physical space for the incident light to illuminate the focusing ring 1, ensuring that a linear light spot is presented and reflected on the focusing ring 1. The recess 201 can be formed by planar cutting or by other methods, which are not limited here. Specifically, the thickness of the workpiece at the recess can be uniform, that is, the depth of the recess is uniform; or, the thickness of the workpiece at the recess can be inconsistent, such as if the recess is an inclined slope, in which case the thickness of the workpiece in the inclined direction can gradually decrease or increase from the center of the workpiece to the outside of the workpiece, which is not limited here, as long as it can reflect the incident light to the focusing ring; or, the recess can be groove-shaped or bowl-shaped, that is, the thickness of the workpiece is the lowest at the center of the recess, and the thickness of the workpiece increases from the center of the recess to the edge of the recess, which is not limited here; such variations are all within the protection scope of the present invention.

[0041] 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 workpiece 2. The light can be transmitted to the 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 can be used to shape or amplify the light transmitted from the optical fiber, so as to facilitate the transmission of the light to the optical element 32 and make the optical element 32 shape the light into a linear light spot.

[0042] Specifically, optical element 32 may include at least one of the following elements: cylindrical lens 32a, flat cylindrical lens, Powell prism 32b, cylindrical lens array, flat cylindrical lens array, and diffractive optical element. In this embodiment, the light beam emitted from light source 31 is shaped to form a one-dimensional extended linear light spot S on the focal plane, replacing the point light spot in the prior art, such as... Figure 2a , 2bAs shown, the linear light spot S has a certain length, which makes 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 workpiece 2 (such as a wafer), thereby forming reflected light that can be detected by the photodetector 33. When the linear light spot S is formed on the focusing ring 1, the photodetector 33 detects the extreme value of the light signal of the linear light spot.

[0043] The photodetector 33 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.

[0044] like Figure 4 As shown, the information acquisition component 4 includes: a microcontroller 41, connected to the light source 31 and the photodetector 33, used to control the operation of the light source 31 and the photodetector 33 and to acquire measurement information; a transmission module 42, used to transmit the measurement information to the processor 5 via wireless or wired communication; wherein, the measurement information includes the light signal of the linear light spot S detected by the photodetector 33, and the processor 5 calculates the lateral distance G between the workpiece edge and the focusing ring 1 based on the light signal.

[0045] Specifically, the transmission module 42 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 41, light source 31, and transmission module 42).

[0046] The first specific embodiment of the above-described gap measurement method can employ the gap measurement device disclosed in the above embodiments, see [link to embodiment]. Figure 3 , Figure 4 As shown, the operation process of the gap measuring device 1 is as follows: 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.

[0047] The measurement steps of this gap measuring device include: 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 optical element 32, and the photodetector 33 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 41. In step S203, the microcontroller 41 or processor 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.

[0048] The above step S203 can be completed by a processor, which can be integrated into workpiece 2 or set up independently, such 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 measuring device provided in this application, such as a computer or industrial control computer that receives, displays or processes wireless data on the gap between the wafer edge and the focusing ring. These variations are all within the protection scope of this application.

[0049] like Figure 5 and Figure 6 In another embodiment of the gap measuring device shown, the optical component 3 includes a light source 301 and an optical element 32. The light source 301 emits a light beam with a set divergence angle toward the focusing ring 1. The optical element 32 projects the light beam onto the focusing ring 1 and forms 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 information acquisition component includes an image acquisition unit 302 and a transmission module. The image acquisition unit 302 acquires image information at the projection position and transmits 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 301 and the focusing ring 1 is calculated, thereby obtaining the lateral distance G between the edge of the workpiece (wafer) and the focusing ring 1.

[0050] In this embodiment, a light source 301 is placed on the workpiece 2 to project a beam of light with a set divergence angle onto the focusing ring 1. The beam is then shaped or converted by an optical element 32 to form a linear light spot on the focusing ring 1. An image acquisition device receives image information from the projection location, including the linear light spot and the portion of the focusing ring 1 containing it. The image information is then processed by a processor to obtain geometric information on the focusing ring 1, including the position of the linear light spot. This allows for the determination of the distance R between the sub-spots within the linear light spot. Using triangulation and 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 workpiece 2 and the focusing ring 1 can then be determined. Further... Figure 5 As shown, the workpiece 2 has a recess 201 that sinks from the upper surface of the workpiece to the lower surface of the workpiece. After the optical element 32 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.

[0051] 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 workpiece. In the preferred embodiment, the recess is not a hole penetrating the workpiece, thereby allowing the workpiece to maintain the normal machinability of a wafer for use in wafer fabrication processes. The depth of the recess is between 0.1 mm and 0.35 mm.

[0052] 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 protection scope of this invention.

[0053] Further, in a preferred embodiment, the recess extends to the edge of the workpiece, meaning the recess begins at the edge of the workpiece. In another variation, the recess is located on the upper surface of the workpiece but does not contact the edge of the workpiece; that is, the recess does not extend to the edge of the workpiece. Those skilled in the art will understand that the above embodiments are all within the scope of protection of this invention.

[0054] A second specific embodiment of the above-described gap measurement method may employ the above-described... Figure 5 , Figure 6 The gap measuring device disclosed herein operates as described in steps S101 to S104 of the first embodiment, and will not be detailed here. The measurement steps of the gap measuring device in this second embodiment include: Step S301: Place the light source 301 on the upper surface of the workpiece 2, and establish a complete optical path connection between the light source 301 and the image acquisition device 302 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 unit 302 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 size R between the two parallel sub-spots based on the light intensity information, that is, 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 workpiece), the processor obtains the lateral spacing G between the edge of the workpiece and the focusing ring 1.

[0055] 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 mounted on the workpiece 2, or the light-emitting element can be externally mounted, with the light beam formed by transmission through an optical fiber mounted on the workpiece 2. The light beam projected by the light source 301 is shaped or converted by optical element 32 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.

[0056] 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 device can be 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 mounted on the workpiece, near the optical component.

[0057] 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 301 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 workpiece and the edge of the workpiece—g gives the lateral spacing G between the edge of the workpiece and the focusing ring 1, i.e., G = LD.

[0058] 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.

[0059] Specifically, the aforementioned optical element 32 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 optical element 32 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 beam emitted from the light source into two bright, parallel straight linear spots, see [reference needed]. Figure 6 As shown, the optical element 32 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).

[0060] 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 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 reflecting mirrors. The reflecting mirrors are used to adjust the distance between the two beams to make them parallel.

[0061] 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 5 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 aforementioned optical element 32, 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 emitters each emit a beam of light, and after being shaped by the optical element, the two beams can form two linear and parallel sub-spots on the focusing ring 1.

[0062] In another embodiment, the optical component further includes a rotation module for driving the optical element to rotate. The rotation module controls the 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 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 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 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.

[0063] Specifically, the movable optical element can be a mirror or a prism, etc. 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 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 drive components.

[0064] In the above embodiments, at least one of the optical component and the information acquisition component is fixed to the surface of the workpiece, such as by attachment or bonding, which is not limited here. It is understood that the fixing method and position of the optical component and the information acquisition component may be the same or different; for example, one of the optical component and the information acquisition component may be fixed to the upper surface of the workpiece, while the other is fixed to the outer peripheral surface of the workpiece; or both may be fixed to the upper surface or the outer peripheral surface of the workpiece. It is understood that there may be multiple optical components, such as two, three, or four, which may be evenly distributed on the workpiece.

[0065] To better accommodate the low height of the focusing ring, preferably, the optical component is fixed within a groove in the workpiece, and the workpiece has an optical path communicating with the groove. This optical path allows incident light to exit to the outside of the workpiece. Understandably, the optical element in the optical component is the last element for the incident light to exit the workpiece. In one embodiment, only the optical element is placed within the groove, allowing the light illuminating the focusing ring to exit from inside the workpiece, 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 workpiece, forming a channel or through-hole. In one embodiment, the information acquisition component can be disposed within the groove of the workpiece, capable of acquiring the image at the projection position on the focusing ring.

[0066] 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.

[0067] In the above embodiments, the processor can be fixed on the workpiece and connected to the information acquisition component; or, the processor can be an independently set host computer and connected to the information acquisition component via wireless communication.

[0068] This application embodiment also provides a method for measuring the gap between a wafer edge and a focusing ring, employing the gap measuring device as described in any of the preceding claims, comprising: The control optical component emits incident light to the focusing ring, and the incident light forms a linear spot on the focusing ring; Receive the reflected light signal and acquire measurement information of the linear light spot; The lateral distance between the workpiece edge and the focusing ring is calculated based on the measurement information.

[0069] In one embodiment, controlling the optical component to emit incident light toward the focusing ring includes: controlling the optical component to emit a beam of light with a divergence angle, and causing the beam of light to form a linear spot on the focusing ring, wherein the linear spot comprises two sub-spots, the method comprising: Image information on the focusing ring is acquired, and the image information contains the linear light spot; Based on the geometric information of the linear light spot and the divergence angle, the distance between the light source and the focusing ring is calculated, thereby obtaining the lateral spacing between the workpiece and the focusing ring. The geometric information of the linear light spot includes the distance between two sub-spots.

[0070] Furthermore, when the optical component is controlled to emit a beam with a divergence angle, and the beam forms a linear spot on the focusing ring, the incident light emitted by the optical component is configured to at least partially strike the workpiece. Even further, the workpiece has a recess that extends from its upper surface to its lower surface, and this recess is located on the side of the workpiece closest to the focusing ring. The incident light is configured to at least partially strike the recess on the workpiece, and after reflection from the recess to the focusing ring, this further ensures that the acquired image information contains a linear spot.

[0071] 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 gap measuring device comprising a workpiece and for measuring the gap between the edge of the workpiece and a focusing ring, wherein the height difference between the upper surface of the focusing ring and the upper surface of the workpiece is not greater than 0.5 mm, and at least the following means are disposed on the workpiece: An optical component is used to emit incident light to the focusing ring and to form a linear light spot on the focusing ring. An information acquisition component is used to acquire measurement information of the linear light spot and transmit the measurement information to a processor, enabling the processor to calculate the lateral distance between the workpiece edge and the focusing ring based on the measurement information.

2. The gap measuring device according to claim 1, characterized in that, The light emitted by the optical component The incident light is configured such that at least a portion of the beam is directed directly onto the workpiece.

3. The gap measuring device as described in claim 2, characterized in that, At least one of the optical component and the information acquisition component is fixed to the surface of the workpiece; or, the optical component is fixed in a groove of the workpiece.

4. The gap measuring device as described in claim 2, characterized in that, The workpiece has a recess that extends from the upper surface of the workpiece to the lower surface of the workpiece, and the recess is located on the side of the workpiece closer to the focusing ring.

5. The gap measuring device according to claim 4, characterized in that, The depth of the depression is between 0.1 mm and 0.35 mm.

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

7. The gap measuring device according to claim 4, characterized in that, The upper surface of the focusing ring is flush with the upper surface of the workpiece.

8. The gap measuring device according to any one of claims 1 to 7, characterized in that, The optical component includes at least: A light source element, used to emit incident light to the focusing ring; An optical element is disposed in the optical path of the incident light, for causing the incident light to form the linear light spot at the projection position of the focusing ring; A photodetector, which is at least used to receive reflected light returning from the focusing ring.

9. The gap measuring device as described in claim 8, 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.

10. The gap measuring device as described in claim 8, characterized in that, The optical assembly further 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, such that the measurement information includes the optical signal of the linear spot and the geometric information of the linear spot, and the geometric information of the linear spot includes the distance between the two sub-spots.

11. The gap measuring device as described in claim 8, 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, such that the measurement information includes the light signal of the linear spot and the geometric information of the linear spot, the geometric information of the linear spot including the distance between the two sub-spots.

12. The gap measuring device as described in claim 8, 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 reach a second angle so that the linear light spot moves a certain distance at the projection position accordingly.

13. The gap measuring device as described in claim 8, 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.

14. The gap measuring device as described in claim 8, characterized in that, The information acquisition component includes: A microcontroller, connected to the light source and the photodetector, is used at least to control the operation of the light source and to acquire the measurement information; A transmission module is used to transmit the measurement information to the processor via wireless or wired communication. The measurement information includes at least the optical signal of the linear light spot, and the processor calculates the lateral distance between the workpiece edge and the focusing ring based on the optical signal.

15. The gap measuring device as described in claim 14, characterized in that, The optical signal includes at least light intensity information. The processor obtains the geometric information of the linear light spot based on the light intensity information and calculates the distance between the light source and the focusing ring, thereby obtaining the lateral spacing between the measuring workpiece and the focusing ring.

16. The gap measuring device as described in claim 15, characterized in that, The optical signal also includes set divergence angle information. The processor calculates the distance between the light source and the focusing ring based on the geometric information and the divergence angle information, thereby obtaining the lateral spacing between the workpiece and the focusing ring.

17. The gap measuring device according to any one of claims 1-7, characterized in that, The processor is fixed to the workpiece and connected to the information acquisition component; or, the processor is a host computer and is connected to the information acquisition component via wireless communication.

18. A method for measuring the gap between a wafer edge and a focusing ring, using the gap measuring device as described in any one of claims 1-17, characterized in that, include: The optical component is controlled to emit incident light toward the focusing ring, and the incident light forms a linear spot on the focusing ring; Receive the reflected light signal returned by the focusing ring and acquire the measurement information of the linear light spot; The lateral distance between the workpiece edge and the focusing ring is calculated based on the measurement information.

19. The gap measurement method as described in claim 18, characterized in that, The method of controlling the optical component to emit incident light toward the focusing ring includes: controlling the optical component to emit a beam of light with a divergence angle, and causing the beam of light to form a linear spot on the focusing ring, wherein the linear spot comprises two linear sub-spots, the method comprising: Image information on the focusing ring is acquired, and the image information contains the linear light spot; Based on the geometric information of the linear light spot and the divergence angle, the distance between the optical component and the focusing ring is calculated, thereby obtaining the lateral spacing between the workpiece and the focusing ring. The geometric information of the linear light spot includes the distance between two sub-spots.

20. The gap measurement method according to claim 18 or claim 19, characterized in that, The incident light emitted by the optical component is configured such that at least a portion of the beam is directed directly onto the workpiece.

21. The gap measurement method according to claim 20, characterized in that, The workpiece has a recess that extends from the upper surface of the workpiece to the lower surface of the workpiece, and the recess is located on the side of the workpiece closer to the focusing ring.

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