Optical measurement assembly, alignment measurement device and alignment measurement method

Abstract

This invention provides an optical measurement component, alignment measurement device, and alignment measurement method, comprising: a workpiece stage for supporting a substrate to be measured; a focal plane measurement module including a first light source, a projection grating, and a first camera, wherein a light beam emitted from the first light source is dispersed into at least three sub-beams through the projection grating, the sub-beams are incident on a substrate to be measured, and at least a portion of the sub-beams are reflected by the substrate to form a first detection light, which is incident on the first camera; an alignment measurement module including a second light source, a first beam splitter prism, and a second camera, wherein a light beam emitted from the second light source is incident on the first beam splitter prism, reflected by the first beam splitter prism onto an alignment mark, and reflected by the alignment mark to form a second detection light; and a workpiece stage driving module for adjusting the vertical position of the workpiece stage. This invention improves the adaptability and stability of the measurement process.

Description

Technical Field

[0001] This invention relates to the field of photolithography, and more particularly to an optical measurement component, an alignment measurement device, and an alignment measurement method. Background Technology

[0002] In the integrated circuit chip manufacturing process, to achieve the desired accuracy of the lithography machine, it is necessary to accurately establish the relationship between the various coordinate systems of the lithography machine, so that the mask, mask stage, objective lens, substrate under test, and workpiece stage can establish a unified positional relationship. This requires calibrating the substrate under test using an alignment measuring device to focus and level it. During alignment, the alignment marks on the substrate under test must be within the detection range of the alignment measuring device to reduce measurement errors caused by defocusing and tilting.

[0003] In existing technologies, laser automatic alignment devices are commonly used for alignment measurements. However, the incident angle of the incident light in these devices is small, resulting in low sensor measurement resolution and affecting the focusing accuracy of the measuring device. Furthermore, the small measurement spot is sensitive to surface variations of the substrate under test, and these variations can easily cause the measurement spot to be lost, preventing the reflection of the measurement spot carrying measurement information. This means the sensor cannot obtain measurement information, leading to measurement failure, poor measurement stability, and poor process adaptability. Additionally, conventional alignment measuring devices struggle to measure alignment marks of different sizes, resulting in poor process adaptability. Summary of the Invention

[0004] The purpose of this invention is to provide an optical measurement component, an alignment measurement device, and an alignment measurement method to improve the adaptability and stability of the measurement process.

[0005] To achieve the above objectives, the present invention provides an optical measurement component, comprising:

[0006] A workpiece stage is used to support the substrate to be tested. A reference plate is provided on the workpiece stage. A plurality of first alignment marks and second alignment marks are respectively provided on the substrate to be tested and the reference plate.

[0007] A focal plane measurement module is used to measure the pose of the upper surface of the substrate under test. It includes a first light source, a projection grating and a first camera. The light beam emitted by the first light source is dispersed into at least three sub-beams through the projection grating. The sub-beams are incident on the substrate under test. At least a portion of the sub-beams are reflected by the substrate under test to form a first detection light. The first detection light is incident on the first camera.

[0008] The alignment measurement module includes a second light source, a first beam splitter prism, and an alignment camera group. The light beam emitted by the second light source is incident on the first beam splitter prism, reflected by the first beam splitter prism onto the first alignment mark or the second alignment mark, and then reflected by the first alignment mark or the second alignment mark to form a second detection light. The second detection light passes through the first beam splitter prism and is incident on the alignment camera group.

[0009] The workpiece stage driving module compares the measurement result obtained by the focal plane measurement module when the substrate under test is in any vertical position with the measurement result obtained by the focal plane measurement module when the reference plate is in the optimal vertical position to obtain the difference. The vertical position of the workpiece stage is adjusted according to the difference, wherein the optimal vertical position is the vertical position when the second alignment mark is in the optimal focal plane of the alignment camera group.

[0010] Optionally, the projection grating is provided with at least three light-transmitting holes, and the light beam emitted by the first light source is dispersed into at least three sub-beams after passing through the light-transmitting holes of the projection grating.

[0011] Optionally, the shape of the light-transmitting hole includes rectangular, circular, or rhomboid.

[0012] Optionally, the focal plane measurement module further includes a first mirror group, a second mirror group, a first reflecting mirror, a second reflecting mirror, and a third mirror group. The first mirror group collimates the light beam emitted by the first light source and projects it onto the projection grating. The second mirror group and the first reflecting mirror sequentially collimate and reflect the sub-beam passing through the projection grating and project it onto the substrate under test. The second reflecting mirror and the third mirror group sequentially reflect and converge the first detection light and project it into the first camera.

[0013] Optionally, the alignment measurement module further includes a fourth mirror group, a third reflecting mirror, and a fifth mirror group. The fourth mirror group and the third reflecting mirror sequentially collimate and reflect the light beam emitted by the second light source and then incident it onto the first beam splitter prism. The fifth mirror group converges the light beam reflected by the first beam splitter prism and then incident it onto the substrate under test, and collimates the second detection light and then incident it onto the first beam splitter prism. The second detection light passes through the first beam splitter prism and is incident into the alignment camera group.

[0014] Optionally, the aligned camera group includes a second camera and at least one third camera, wherein the second camera and the third camera have different field-of-view sizes; when the aligned camera group includes at least two third cameras, the field-of-view size of each third camera is different.

[0015] Optionally, the alignment measurement module further includes a sixth mirror group and at least one second beam splitter prism. The sixth mirror group and the second camera are sequentially arranged along the optical path to form a first detection branch. After the second detection light passes through the first beam splitter prism, the sixth mirror group converges the second detection light and projects it into the second camera. A second beam splitter prism and the third camera are sequentially arranged along the optical path to form a second detection branch. The alignment measurement module has at least one second detection branch. The second beam splitter prism is located between the first beam splitter prism and the second camera. After the second detection light passes through the first beam splitter prism, a portion of the second detection light passes through the second beam splitter prism and is projected into the second camera. The other portion of the second detection light is reflected by the second beam splitter prism into the third camera.

[0016] Optionally, the second detection branch is further provided with a seventh mirror group, a fourth reflecting mirror and an eighth mirror group. The seventh mirror group, the fourth reflecting mirror and the eighth mirror group are collimated, reflected and converged by the second detection light reflected by the second beam splitter prism and then incident into the third camera.

[0017] Optionally, the angle between each of the sub-beams and the normal of the substrate under test is greater than 45 degrees.

[0018] Optionally, both the first light source and the second light source are monochrome LEDs or halogen lamps.

[0019] Optionally, the second light source includes a first light-emitting component, a second light-emitting component, a third light-emitting component, a first dichroic filter, and a second dichroic filter. The light beam emitted by the first light-emitting component passes through the first dichroic filter and the second dichroic filter in sequence to form a first light beam. The light beam emitted by the second light-emitting component is reflected by the first dichroic filter and then passes through the second dichroic filter to form a second light beam. The light beam emitted by the third light-emitting component is reflected by the second dichroic filter to form a third light beam.

[0020] The light beam emitted by the second light source is a combination of any two or all of the first light beam, the second light beam, and the third light beam; or, the light beam emitted by the second light source is the first light beam, the second light beam, or the third light beam.

[0021] Optionally, the second light source further includes a ninth lens group, a tenth lens group, an eleventh lens group, a twelfth lens group, and a thirteenth lens group. The ninth lens group collimates the light beam emitted by the first light-emitting component and directs it onto the first dichroic filter. The twelfth lens group collimates the light beam emitted by the second light-emitting component and directs it onto the first dichroic filter. The thirteenth lens group collimates the light beam emitted by the third light-emitting component and directs it onto the second dichroic filter. The tenth lens group collimates the light beam transmitted through the first dichroic filter and the light beam reflected by the first dichroic filter and directs it onto the second dichroic filter. The eleventh lens group collimates the light beam transmitted through the second dichroic filter and the light beam reflected by the second dichroic filter and directs it out.

[0022] Optionally, the substrate to be tested is a metal mask.

[0023] Optionally, the alignment measurement module further includes a third light source located between the first beam splitter prism and the substrate under test, for illuminating the substrate under test.

[0024] Optionally, the third light source is a ring lamp, and the light beam emitted by the second light source and the second detection light both pass through the inner ring surface of the ring lamp.

[0025] An alignment measuring device, comprising:

[0026] Base;

[0027] A gantry frame structure is mounted on the base.

[0028] The optical measurement component described above is mounted on the gantry structure, which is used to drive the optical measurement component to move along the X, Y, and Z directions.

[0029] An alignment measurement method, comprising:

[0030] Step S1: Provide a substrate to be tested, place the substrate to be tested on a workpiece stage, and the substrate to be tested has a plurality of first alignment marks;

[0031] Step S2: Use the focal plane measurement module to obtain the focal plane measurement value corresponding to each of the first alignment marks;

[0032] Step S3: Compare the focal plane measurement value corresponding to each first alignment mark with the focal plane zero value of the alignment camera group. When the difference between the focal plane measurement value corresponding to each first alignment mark and the focal plane zero value of the alignment camera group is less than or equal to a set threshold, use the alignment camera group to obtain the center coordinate values ​​of all first alignment marks. When the difference between the focal plane measurement value of any first alignment mark and the focal plane zero value of the alignment camera group is greater than the set threshold, adjust the vertical height of the workpiece stage according to the difference, and execute step S2.

[0033] Optionally, the aligned camera group includes a second camera and a third camera;

[0034] In step S3, either the second camera or the third camera is selected as a specific camera. The focal plane measurement value corresponding to each first alignment mark is compared with the focal plane zero value of the specific camera. When the difference between the focal plane measurement value corresponding to each first alignment mark and the focal plane zero value of the specific camera is less than or equal to the set threshold, the center coordinate values ​​of all first alignment marks are obtained using the specific camera. When the difference between the focal plane measurement value of any first alignment mark and the focal plane zero value of the specific camera is greater than the set threshold, the vertical height of the workpiece stage is adjusted according to the difference, and step S2 is executed.

[0035] Optionally, the step of selecting either the second camera or the third camera as a specific camera includes:

[0036] Images of the first alignment mark are acquired using the second camera and the third camera respectively. The clarity of the images acquired by the second camera and the third camera is compared, and the one with better clarity is selected as the specific camera.

[0037] Optionally, the focal plane zero-point value of the aligned camera group includes the focal plane zero-point value of the second camera or the third camera, and the step of obtaining the focal plane zero-point value of the second camera or the third camera includes:

[0038] The workpiece stage is provided with a reference plate, and the reference plate has a number of second alignment marks.

[0039] The reference plate is moved vertically according to a set step size, and at each vertical position, the second camera or the third camera acquires an image of the second alignment mark, and the sharpness of all images acquired by the second camera or the third camera is compared.

[0040] The vertical position corresponding to the image with the best clarity among all images acquired by the second camera or the third camera is taken as the optimal vertical position of the second camera or the third camera;

[0041] Move the reference plate to the optimal vertical position of the second camera or the third camera, and use the focal plane measurement module to obtain the focal plane measurement value corresponding to the second alignment mark as the focal plane zero value of the second camera or the third camera.

[0042] In the optical measurement component, alignment measurement device, and alignment measurement method provided by this invention, the light beam emitted by the first light source in the focal plane measurement module is dispersed into at least three sub-beams through a projection grating. All sub-beams are incident on a substrate under test. When the surface shape of the substrate under test fluctuates significantly, it is not easy for all sub-beams to be sacrificed; at least some sub-beams will be reflected by the substrate under test. The first camera can receive the first detection light reflected back from the substrate under test, making the measurement more stable and applicable to the measurement of substrates with different surface shapes. Furthermore, if the surface shape of the substrate under test is good, the substrate under test can reflect more sub-beams. The first camera can receive multiple first detection lights reflected from the substrate under test. Based on these multiple first detection lights, it obtains the focal plane measurement value corresponding to the first alignment mark, making the measured focal plane measurement value more accurate and improving the stability of the measurement results. Furthermore, by combining the focal plane measurement module and the alignment measurement module, the workpiece stage driving module compares the measurement results obtained by the focal plane measurement module when the substrate under test is in any vertical position with the measurement results obtained by the focal plane measurement module when the reference plate is in the optimal vertical position. Based on the comparison results, the vertical position of the workpiece stage is adjusted, improving the applicability and accuracy of the measurement process. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the structure of the optical measurement component provided in Embodiment 1 of the present invention;

[0044] Figure 2 This is a cross-sectional schematic diagram of the projection grating in the optical measurement assembly provided in Embodiment 1 of the present invention;

[0045] Figure 3 This is a schematic diagram of the imaging signal of the focal plane measurement module in the optical measurement assembly provided in Embodiment 1 of the present invention;

[0046] Figure 4 This is a schematic diagram of the alignment measuring device provided in Embodiment 1 of the present invention;

[0047] Figure 5 A flowchart of the alignment measurement method provided in Embodiment 1 of the present invention;

[0048] Figure 6This is a schematic diagram showing the peak positions of the first detection light at different vertical positions in the alignment measurement method provided in Embodiment 1 of the present invention.

[0049] Figure 7 This is a schematic diagram illustrating the clarity of different vertical positions in the alignment measurement method provided in Embodiment 1 of the present invention;

[0050] Figure 8 This is a schematic diagram of the structure of the second light source in the optical measurement assembly provided in Embodiment 2 of the present invention;

[0051] Figure 9 This is a schematic diagram of the structure of the optical measurement component provided in Embodiment 3 of the present invention;

[0052] The attached figures are labeled as follows:

[0053] 10-Focal plane and alignment measurement unit; 11-Focal plane measurement module; 12-Alignment measurement module; 111-First light source; 112-First mirror group; 113-Projection grating; 114-Second mirror group; 115-First reflecting mirror; 116-Second reflecting mirror; 117-Third mirror group; 118-First camera; 121, 121'-Second light source; 122-Fourth mirror group; 123-Third reflecting mirror; 124-First beam splitter prism; 125-Fifth mirror group; 126-Sixth mirror group; 127-Second camera; 128-Third light source; 131A, 131B-Second beam splitter prism; 132A, 132B-Seventh mirror group; 133A, 133B-Fourth reflecting mirror; 134A, 134B-Eighth mirror group; 13 5A, 135B - Third camera; 60, 100 - Substrate under test; 113A, 113B, 113C - Light-transmitting aperture; 141 - First light-emitting component; 142 - Second light-emitting component; 143 - Third light-emitting component; 144 - Ninth lens group; 145 - First dichroic filter; 146 - Tenth lens group; 147 - Second dichroic filter; 148 - Eleventh lens group; 149 - Twelfth lens group; 150 - Thirteenth lens group; 20 - Support body; 21 - X-guide rail; 22 - Y-guide rail; 23 - Z-guide rail; 24 - Sliding block; 25 - Vertical slide; 31 - Vibration damping platform; 32 - Workpiece stage support; 40 - Workpiece stage; 50 - Reference plate; 51 - Second alignment mark; 61 - First alignment mark; 70 - Computer system. Detailed Implementation

[0054] The specific embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0055] Example 1

[0056] Figure 1 This is a schematic diagram of the optical measurement assembly provided in this embodiment. This embodiment provides an optical measurement assembly to improve the adaptability and stability of measurement processes. Please refer to [reference needed]. Figure 1 The optical measurement assembly includes a workpiece stage, a workpiece stage driving module, a focal plane measurement module 11, and an alignment measurement module 12. The workpiece stage is used to support the substrate to be measured, and a reference plate is provided on the workpiece stage. Several first alignment marks are provided on the substrate to be measured, and several second alignment marks are provided on the reference plate.

[0057] The focal plane measurement module 11 includes a first light source 111, a first mirror group 112, a projection grating 113, a second mirror group 114, a first reflecting mirror 115, a second reflecting mirror 116, a third mirror group 117, and a first camera 118. The first light source 111 emits a light beam, which is collimated by the first mirror group 112 and incident onto the projection grating 113. The light beam emitted by the first light source 111 is dispersed into at least three sub-beams by the projection grating 113. The second mirror group 114 and the first reflecting mirror 115 sequentially disperse the light beams emitted by the projection grating. The three sub-beams of 113 are collimated and reflected before being incident on the substrate 100 under test. They can be incident on the first alignment mark on the substrate 100, or on other positions on the substrate 100 besides the first alignment mark. At least a portion of the sub-beams are reflected by the substrate 100 to form a first detection light corresponding to the sub-beams. The number of first detection lights is the same as the number of sub-beams reflected by the substrate 100. The second reflector 116 and the third mirror group 117 sequentially reflect and converge the first detection light before it is incident on the first camera 118. Because the light beam emitted by the first light source 111 is dispersed into at least three sub-beams through the projection grating 113, in... Figure 1 In order to clearly show the optical path of the light beam emitted by the first light source 111, in Figure 1 The image shows only one sub-beam and the optical path of one first detection beam. The optical path of the first detection beam at the first vertical position is as follows: Figure 1 As shown by the solid line, when the substrate 100 under test moves to the second vertical position, the optical path of the first detection light is as follows: Figure 1 As shown by the dashed line. In this embodiment, in order to increase the measurement resolution of the first camera 118 and improve the focusing accuracy and efficiency of the measurement, it is required that the angle between each sub-beam and the normal of the substrate 100 under test is greater than 45 degrees.

[0058] Figure 2 This is a cross-sectional schematic diagram of the projection grating in the optical measurement assembly provided in this embodiment. In this embodiment, the projection grating 113 is provided with at least three light-transmitting holes. Please refer to [reference needed]. Figure 2 ,exist Figure 2The image shows three light-transmitting holes 113A, 113B, and 113C. The shapes of the light-transmitting holes 113A, 113B, and 113C include rectangles, circles, or rhombuses. For example, the light-transmitting holes 113A, 113B, and 113C can be rectangles with a length of 2 mm and a width of 100 μm, but are not limited to this shape.

[0059] The light beam emitted by the first light source 111 is dispersed into at least three sub-beams after passing through the light aperture of the projection grating 113. All sub-beams are incident on the substrate 100 under test. When the surface shape of the substrate 100 under test fluctuates greatly, multiple sub-beams are not easily sacrificed. At least some of the sub-beams will be reflected by the substrate under test. The first camera 118 can receive the first detection light reflected back from the substrate 100 under test, making the measurement more stable and applicable to the measurement of substrates 100 under test with different surface shapes.

[0060] Figure 3 This is a schematic diagram of the imaging signal of the focal plane measurement module in the optical measurement assembly provided in this embodiment. Please refer to... Figure 3 ,exist Figure 3 The example shows the waveforms of the three first detection lights acquired by the first camera 118. Each first detection light has a peak position, and the gray level is highest at each peak position. Figure 3 The solid line represents the waveforms of the three first detection lights acquired by the first camera 118 at the first vertical position, and the dashed line represents the waveforms of the three first detection lights acquired by the first camera 118 at the second vertical position. It can be seen that the waveforms of the three first detection lights acquired by the first camera 118 will be shifted at different vertical positions.

[0061] Please refer to Figure 1 The alignment measurement module 12 includes a second light source 121, a fourth mirror group 122, a third reflecting mirror 123, a first beam splitter prism 124, a fifth mirror group 125, and an alignment camera group. The second light source 121 emits a light beam. The fourth mirror group 122 and the third reflecting mirror 123 sequentially collimate and reflect the light beam emitted by the second light source 121 before it is incident on the first beam splitter prism 124. The beam is reflected by the first beam splitter prism 124. The fifth mirror group 125 converges the light beam reflected by the first beam splitter prism 124 and incident perpendicularly on a first alignment mark or a second alignment mark. The beam is reflected by the first alignment mark or the second alignment mark to form a second detection light. The second detection light is collimated by the fifth mirror group 125 and incident on the first beam splitter prism 124. The second detection light passes through the first beam splitter prism 124 and enters the alignment camera group. The alignment camera group includes a second camera 127 and at least one third camera. Figure 1 Two third cameras, 135A and 135B, are shown in the image.

[0062] The alignment measurement module 12 also includes a sixth lens group 126, wherein the sixth lens group 126 and the second camera 127 are arranged sequentially along the optical path to form a first detection branch. After the second detection light passes through the first beam splitter prism 124, the sixth lens group 126 converges the second detection light and then projects it into the second camera 127.

[0063] Furthermore, the alignment measurement module 12 also includes at least one second beam splitter prism 131A, 131B, a seventh mirror group 132A, 132B, a fourth reflecting mirror 133A, 133B, an eighth mirror group 134A, 134B, and a third camera 135A, 135B. A second beam splitter prism and a third camera are sequentially arranged along the optical path to form a second detection branch. The alignment measurement module has at least one second detection branch. Figure 1 The diagram shows two second detection branches. Second beam-splitting prisms 131A and 131B are both located between the first beam-splitting prism 124 and the second beam-splitting prism 127. After the second detection light passes through the first beam-splitting prism 124, a portion of the second detection light passes through the second beam-splitting prisms 131A and 131B and is incident on the second camera 127. The other portion is reflected by the second beam-splitting prisms 131A and 131B to the third cameras 135A and 135B. Specifically, the seventh lens group 132A and 132B, the fourth reflecting mirror 133A and 133B, and the eighth lens group 134A and 134B sequentially collimate, reflect, and converge the second detection light reflected by the second beam-splitting prisms 131A and 131B before incident on the third cameras 135A and 135B. In this embodiment, the first light source 111 and the second light source 121 are both monochrome LEDs or halogen lamps, but are not limited to these.

[0064] In this embodiment, the second and third cameras have different field-of-view sizes. When there are two or more third cameras, the field-of-view size of each third camera is different. For example, in... Figure 1 The field-of-view ratio of the second camera 127 to the two third cameras 135A and 135B can be 1:2:4, but is not limited to this ratio. By setting up an alignment camera group in the alignment measurement module, and with different field-of-view sizes between each camera, a specific camera can be selected from the second and third cameras according to the size of the first alignment mark, and measurement can be performed through that specific camera to improve the process adaptability of the measurement.

[0065] The workpiece stage driving module compares the measurement results obtained by the focal plane measurement module when the substrate under test is in any vertical position with the measurement results obtained by the focal plane measurement module when the reference plate is in the optimal vertical position to obtain the difference. The vertical position of the workpiece stage is adjusted according to the difference, where the optimal vertical position is the vertical position when the second alignment mark is in the optimal focal plane of the alignment camera group. Combining the focal plane measurement module and the alignment measurement module to measure the substrate under test can provide the process applicability and accuracy of the measurement.

[0066] Figure 4 This is a schematic diagram of the alignment measuring device provided in this embodiment. This embodiment also provides an alignment measuring device; please refer to [the provided text]. Figure 4 This includes: a base, a gantry structure, and the optical measurement assembly described above, wherein the optical measurement assembly includes a workpiece stage 40, a focal plane measurement module, an alignment measurement module, and a workpiece stage drive module. Figure 4 The focal plane measurement module and the alignment measurement module are not shown separately; that is, the focal plane measurement module and the alignment measurement module are represented by the focal plane and alignment measurement unit 10.

[0067] The base includes a workpiece stage support 32 and a vibration damping platform 31. The workpiece stage support 32 is mounted on the vibration damping platform 31. The workpiece stage 40 is mounted on the workpiece stage support 32 and is used to support the substrate 60 to be tested. A gantry structure is mounted on the base. Specifically, the gantry structure includes a support body 20, an X-axis guide rail 21, a Y-axis guide rail 22, a Z-axis guide rail 23, a vertical slide 25, and a sliding block 24. The X-axis guide rail 21, Y-axis guide rail 22, and Z-axis guide rail 23 are mounted on the support body 20. The support body 20 is mounted on the vibration damping platform 31 via the Y-axis guide rail 22, which drives the support body 20 to move along the Y direction. The sliding block 24 is mounted on the support body 20 via the X-axis guide rail 21. X-guide rail 21 drives sliding block 24 to move along the X direction; Z-guide rail 23 is disposed on sliding block 24, and vertical slide 25 is disposed on sliding block 24 via Z-guide rail 23, driving vertical slide 25 to move along the Z direction; focal plane and alignment measurement unit 10 is disposed on vertical slide 25, that is, focal plane and alignment measurement unit 10 is disposed on gantry structure and located above workpiece stage 40, gantry structure is used to drive focal plane and alignment measurement unit 10 to move along X, Y, and Z directions. Further, reference plate 50 is disposed on workpiece stage 40, reference plate 50 is disposed on reference plate 50 and several second alignment marks 51 are disposed on reference plate 50; substrate 60 to be measured is placed on workpiece stage 40, substrate 60 to be measured is disposed on substrate 60 and several first alignment marks 61 are disposed on substrate 60. It also includes computer system 70, through which the movement of gantry structure and workpiece stage 40 can be controlled and the data measured by optical measurement components can be obtained.

[0068] Figure 5This is a flowchart of the alignment measurement method provided in this embodiment. This embodiment also provides an alignment measurement method; please refer to [the provided text]. Figure 5 This includes:

[0069] Step S1: Provide the substrate to be tested, place the substrate to be tested on the workpiece stage, and the substrate to be tested has a number of first alignment marks;

[0070] Step S2: Use the focal plane measurement module to obtain the focal plane measurement value corresponding to each first alignment mark;

[0071] Step S3: Compare the focal plane measurement value corresponding to each first alignment mark with the focal plane zero value of the alignment camera group. When the difference between the focal plane measurement value corresponding to each first alignment mark and the focal plane zero value of the alignment camera group is less than or equal to a set threshold, obtain the center coordinate values ​​of all first alignment marks using the alignment camera group. When the difference between the focal plane measurement value of any first alignment mark and the focal plane zero value of the alignment camera group is greater than the set threshold, adjust the vertical height of the substrate under test according to the difference, and execute step S2.

[0072] The alignment measurement method provided in this embodiment will be described in detail below.

[0073] Step S1: Provide a substrate to be tested, place the substrate to be tested on the workpiece stage, and the substrate to be tested has several first alignment marks.

[0074] Specifically, the substrate to be tested can be a silicon wafer, a ceramic plate, a glass plate, etc. The substrate to be tested is provided with several first alignment marks, the shape of which can be a cross, a rectangle, etc. The substrate to be tested is placed on the workpiece stage.

[0075] Step S2: Use the focal plane measurement module to obtain the focal plane measurement value corresponding to each first alignment mark.

[0076] Specifically, the focal plane measurement module includes a first light source and a first camera. The first light source emits a light beam, which is incident on a first alignment mark on the substrate under test. After being reflected by the substrate under test, it forms a first detection light. The first detection light is incident on the first camera, and the first camera obtains the focal plane measurement value corresponding to the first alignment mark, thereby obtaining the focal plane measurement value corresponding to each first alignment mark.

[0077] In this embodiment, since the movement of the workpiece stage and the data acquired by the first camera are not of the same scale, for example, the movement of the workpiece stage can be measured in micrometers (µm), while the data acquired by the first camera is the position reading in the target surface coordinate system of the first camera. The two do not belong to the same dimension. In order to better calibrate the scale relationship between the two, it is necessary to obtain coefficients and compensation constants to convert the two so that the movement of the workpiece stage can be known from the data acquired by the first camera.

[0078] Figure 6 This diagram illustrates the peak positions of the first detection light at different vertical positions in the alignment measurement method provided in this embodiment. Specifically, a reference plate is provided and placed on the workpiece stage. The reference plate has several second alignment marks. The reference plate is moved vertically according to a set step size. At each vertical position, the first camera acquires the position readings of the peak positions of all the first detection lights in the first camera target surface coordinate system. The average value of the position readings of the peak positions of all the first detection lights in the first camera target surface coordinate system is calculated. Please refer to [reference needed]. Figure 6 ,from Figure 6 The system can determine that the peak position of the first detection light differs at different vertical positions. An equation is established using the average position readings of each vertical position in the first camera target surface coordinate system, and the coefficients are obtained using the least squares method. A compensation constant is obtained using the coordinates and coefficients of the center position in the first camera target surface coordinate system. Specifically, the product of the coordinates and coefficients of the center position in the first camera target surface coordinate system is added to the compensation constant, and the output is zero to obtain the compensation constant. The coefficients and compensation constant are saved as machine constants for easy conversion between the workpiece stage and the focal plane measurement module during subsequent measurements.

[0079] Step S3: Compare the focal plane measurement value corresponding to each first alignment mark with the focal plane zero value of the alignment camera group. When the difference between the focal plane measurement value corresponding to each first alignment mark and the focal plane zero value of the alignment camera group is less than or equal to a set threshold, obtain the center coordinate values ​​of all first alignment marks using the alignment camera group. When the difference between the focal plane measurement value of any first alignment mark and the focal plane zero value of the alignment camera group is greater than the set threshold, adjust the vertical height of the substrate under test according to the difference, and execute step S2.

[0080] Specifically, the focal plane measurement value corresponding to the first alignment mark is compared with the focal plane zero value of the alignment camera group. When the difference between the focal plane measurement value of the first alignment mark and the focal plane zero value of the alignment camera group is less than or equal to a set threshold, the center coordinate value of the first alignment mark is obtained using the alignment camera group, that is, the center coordinate value of the first alignment mark in the target surface coordinate system of the alignment camera group. The center coordinate value of the first alignment mark in the target surface coordinate system of the alignment camera group can be obtained by calculating the centroid of the first alignment mark after edge detection. The center coordinate value of the first alignment mark in the target surface coordinate system of the alignment camera group is then converted to the coordinate system of the alignment measuring device. This allows us to know the positional difference between the center coordinate value of the first alignment mark in the coordinate system of the alignment measuring device and the nominal center coordinate value of the first alignment mark. The nominal center coordinate value of the first alignment mark is the position of the first alignment mark defined during the design. When the difference between the focal plane measurement value of the first alignment mark and the focal plane zero value of the alignment camera group is greater than the set threshold, the vertical height of the workpiece stage is adjusted according to the difference, and step S2 is executed; in this way, the measurement of all the first alignment marks is completed, and the center coordinate values ​​of all the first alignment marks in the coordinate system of the alignment measuring device are obtained.

[0081] In this embodiment, the alignment camera group includes a second camera and a third camera, with different field-of-view sizes. In step S3, either the second or third camera is selected as a specific camera. The focal plane measurement value of the first alignment mark is compared with the focal plane zero value of the specific camera. When the difference between the focal plane measurement value of the first alignment mark and the focal plane zero value of the specific camera is less than or equal to a set threshold, the center coordinate value of the first alignment mark is obtained using the specific camera, i.e., the center coordinate value of the first alignment mark in the target surface coordinate system of the specific camera. The center coordinate value of the first alignment mark in the target surface coordinate system of the specific camera can be obtained by calculating the centroid of the first alignment mark after edge detection. The center coordinate value of the first alignment mark in the target surface coordinate system of the specific camera is then converted to the coordinate system of the alignment measuring device, which reveals the positional difference between the center coordinate value of the first alignment mark in the coordinate system of the alignment measuring device and the nominal center coordinate value of the first alignment mark during design. When the difference between the focal plane measurement value of the first alignment mark and the focal plane zero value of a specific camera is greater than a set threshold, the vertical height of the workpiece stage is adjusted according to the difference, and step S2 is executed; in this way, the measurement of all the first alignment marks is completed, and the center coordinate values ​​of all the first alignment marks in the coordinate system of the alignment measuring device are obtained.

[0082] Furthermore, the step of selecting either the second camera or the third camera as a specific camera includes: acquiring images of the first alignment mark using the second camera and the third camera respectively, comparing the clarity of the images acquired by the second camera and the third camera, and selecting the one with better clarity as the specific camera.

[0083] Figure 7 This is a schematic diagram illustrating the sharpness at different vertical positions in the alignment measurement method provided in this embodiment. Further, the focal plane zero-point value of the alignment camera group includes the focal plane zero-point value of the second camera or the third camera. The step of obtaining the focal plane zero-point value of the second camera or the third camera includes: a reference plate is set on the workpiece stage, and the reference plate has several second alignment marks; the reference plate is moved vertically according to a set step size, and at each vertical position, the second camera or the third camera acquires an image of the second alignment mark, and the sharpness of all images acquired by the second camera or the third camera is compared; please refer to... Figure 7 The sharpness varies at different vertical positions. The vertical position corresponding to the image with the best sharpness among all images acquired by the second or third camera is taken as the optimal vertical position of the second or third camera. The reference plate is moved to the optimal vertical position of the second or third camera, and the focal plane measurement value corresponding to the second alignment mark is obtained by the focal plane measurement module as the focal plane zero value of the second or third camera.

[0084]

Example 2

[0085] Figure 8 This is a schematic diagram of the structure of the second light source in the optical measurement assembly provided in this embodiment. Please refer to... Figure 8 The difference from Embodiment 1 is that the second light source 121' in the optical measurement component of this embodiment includes a first light-emitting component 141, a second light-emitting component 142, a third light-emitting component 143, a first dichroic filter 145, and a second dichroic filter 147. The light beam emitted by the first light-emitting component 141 passes through the first dichroic filter 145 and the second dichroic filter 147 in sequence to form a first light beam. The light beam emitted by the second light-emitting component 142 is reflected by the first dichroic filter 145 and passes through the second dichroic filter 147 to form a second light beam. The light beam emitted by the third light-emitting component 143 is reflected by the second dichroic filter 147 to form a third light beam.

[0086] Furthermore, the second light source 121 also includes a ninth lens group 144, a tenth lens group 146, an eleventh lens group 148, a twelfth lens group 149, and a thirteenth lens group 150. The ninth lens group 144 collimates the light beam emitted by the first light-emitting component 141 and directs it onto the first dichroic filter 145. The twelfth lens group 149 collimates the light beam emitted by the second light-emitting component 142 and directs it onto the first dichroic filter 146. The thirteenth lens group 150 collimates the light beam emitted by the third light-emitting component 143 and directs it onto the second dichroic filter 147. The tenth lens group 146 collimates the light beam transmitted through the first dichroic filter 145 and the light beam reflected by the first dichroic filter 145 and directs it onto the second dichroic filter 147. The eleventh lens group 148 collimates the light beam transmitted through the second dichroic filter 145 and the light beam reflected by the second dichroic filter 147 and then outputs it. In this embodiment, the light-emitting colors of the first light-emitting component 141, the second light-emitting component 142, and the third light-emitting component 143 can be all different or partially different. For example, the light-emitting colors of the first light-emitting component 141, the second light-emitting component 142, and the third light-emitting component 143 can be red, green, and blue, respectively, or the light-emitting colors of the first light-emitting component 141, the second light-emitting component 142 can be white, and the light-emitting color of the third light-emitting component 143 can be blue. Furthermore, the light-transmitting color and the light-reflecting color of the first dichroic color filter 146 and the second dichroic color filter 147 can be configured according to the light-emitting colors of the first light-emitting component 141, the second light-emitting component 142, and the third light-emitting component 143. The light beam emitted by the second light source 121' is a combination beam composed of any two of the first beam, the second beam, and the third beam, or a combination beam composed of all of them; or, the light beam emitted by the second light source is the first beam, the second beam, or the third beam. By freely configuring the three light-emitting components, the adaptability of the measurement process can be improved.

[0087]

Example 3

[0088] Figure 9 This is a schematic diagram of the optical measurement assembly provided in this embodiment. Please refer to... Figure 9 The difference from Embodiment 1 is that the optical measurement component in this embodiment further includes a third light source 128, which is located between the first beam-splitting prism 124 and the substrate 100 under test, and is used to illuminate the substrate 100 under test. Furthermore, the third light source 128 is a ring lamp, and the beam emitted by the second light source 121 and the second detection light both pass through the inner ring surface of the ring lamp. In this embodiment, the substrate 100 under test is a metal mask. Since the metal mask has many metal micropores, it can easily affect the images acquired by the second camera 127 or the third cameras 135A and 135B. Therefore, setting the third light source 128 can help to achieve clear imaging of the first alignment mark or the second alignment mark.

[0089] In summary, in the optical measurement component, alignment measurement device, and alignment measurement method provided by this invention, the light beam emitted by the first light source in the focal plane measurement module is dispersed into at least three sub-beams through a projection grating. All sub-beams are incident on a substrate under test. When the surface shape of the substrate under test fluctuates significantly, multiple sub-beams are less likely to be completely lost; at least some sub-beams will be reflected by the substrate under test. The first camera can receive the first detection light reflected back from the substrate under test, making the measurement more stable and applicable to measurements of substrates with different surface shapes. Furthermore, if the surface shape of the substrate under test is good, the substrate can reflect more sub-beams. The first camera can receive multiple first detection lights reflected from the substrate under test. Based on the multiple first detection lights, the focal plane measurement value corresponding to the first alignment mark is obtained, making the measured focal plane measurement value more accurate and improving the stability of the measurement result. Furthermore, by combining the focal plane measurement module and the alignment measurement module, the measurement result obtained by the focal plane measurement module when the substrate under test is in any vertical position is compared with the measurement result obtained by the focal plane measurement module when the reference plate is in the optimal vertical position through the workpiece stage driving module. Based on the comparison result, the vertical position of the workpiece stage is adjusted, which improves the applicability and accuracy of the measurement process.

[0090] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. An optical measurement assembly, characterized by The utility model relates to a kind of alignment measurement systems, including: Workpiece table, for carrying the substrate to be measured, reference version is equipped on the workpiece table, the substrate to be measured and the reference version are equipped with a plurality of first alignment mark and second alignment mark respectively; Focal plane measurement module, for measuring the pose of the upper surface of the substrate to be measured, including first light source, projection grating and first camera, at least three light transmission holes are provided on the projection grating, the light beam emitted by the first light source is dispersed into at least three sub-beams after passing through the light transmission hole of the projection grating, each of the sub-beams is incident on the substrate to be measured and the angle between each of the sub-beams and the normal line of the substrate to be measured is greater than 45 degrees, at least part of the sub-beams is reflected by the substrate to be measured to form first detection light, and the first detection light is incident in the first camera; Alignment measurement module, including second light source, first beam splitter prism and alignment camera group, the light beam emitted by the second light source is incident on the first beam splitter prism, reflected by the first beam splitter prism on the first alignment mark or the second alignment mark, and forms second detection light after being reflected by the first alignment mark or the second alignment mark, the second detection light passes through the first beam splitter prism and is incident in the alignment camera group, the alignment camera group includes second camera and at least one third camera, the field of view size of the second camera is different from that of the third camera; Workpiece table driving module, the measurement result measured by the focal plane measurement module when the substrate to be measured is in any vertical position is compared with the measurement result measured by the focal plane measurement module when the reference version is in the best vertical position to obtain the difference value, and the vertical position of the workpiece table is adjusted according to the difference value, wherein the best vertical position is the vertical position when the second alignment mark is in the best measurement focal plane of the alignment camera group.

2. The optical measurement assembly of claim 1, wherein, The shape of the light transmission hole includes rectangle, circle or diamond.

3. The optical measurement assembly of claim 1, wherein, The focal plane measurement module further includes first mirror group, second mirror group, first reflector, second reflector and third mirror group, the light beam emitted by the first light source is collimated and incident on the projection grating after the first mirror group, the second mirror group and the first reflector are sequentially collimated and reflected to the substrate to be measured after passing through the projection grating, the second reflector and the third mirror group are sequentially reflected and converged to the first camera after the first detection light is reflected and converged.

4. The optical measurement assembly of claim 1, wherein, The alignment measurement module further includes fourth mirror group, third reflector and fifth mirror group, the fourth mirror group and the third reflector are sequentially collimated and reflected to the first beam splitter prism after the light beam emitted by the second light source is collimated and reflected, the fifth mirror group converges the light beam reflected by the first beam splitter prism to the substrate to be measured and collimates the second detection light to the first beam splitter prism, and the second detection light passes through the first beam splitter prism and is incident in the alignment camera group.

5. The optical measurement assembly of claim 1 or 4, wherein, When the alignment camera group includes at least two third cameras, the field of view size of each of the third cameras is different.

6. The optical measurement assembly of claim 5, wherein, The alignment measurement module further comprises a sixth mirror group and at least one second beam splitter prism, the sixth mirror group and the second camera are sequentially arranged along the light path direction to form a first detection branch, after the second detection light transmits through the first beam splitter prism, the sixth mirror group converges the second detection light and then the second detection light is incident into the second camera; one second beam splitter prism and one third camera are sequentially arranged along the light path direction to form a second detection branch, the alignment measurement module has at least one second detection branch, the second beam splitter prism is located between the first beam splitter prism and the second camera, after the second detection light transmits through the first beam splitter prism, part of the second detection light transmits through the second beam splitter prism and is incident into the second camera, and the other part of the second detection light is reflected by the second beam splitter prism into the third camera.

7. The optical measurement assembly of claim 6, wherein, The seventh mirror group, the fourth reflector and the eighth mirror group are sequentially arranged on the second detection branch, and the seventh mirror group, the fourth reflector and the eighth mirror group collimate, reflect and converge the second detection light reflected by the second beam splitter prism and then the second detection light is incident into the third camera.

8. The optical measurement assembly of claim 1, wherein, The first light source and the second light source are both single-color LEDs or halogen lamps.

9. The optical measurement assembly of claim 1, wherein, The second light source comprises a first light-emitting component, a second light-emitting component, a third light-emitting component, a first dichroic sheet and a second dichroic sheet, the light beam emitted by the first light-emitting component transmits through the first dichroic sheet and the second dichroic sheet in sequence to form a first light beam, the light beam emitted by the second light-emitting component is reflected by the first dichroic sheet and then transmits through the second dichroic sheet to form a second light beam, and the light beam emitted by the third light-emitting component is reflected by the second dichroic sheet to form a third light beam. The light beam emitted by the second light source is a combined light beam composed of any two or all of the first light beam, the second light beam and the third light beam; or the light beam emitted by the second light source is the first light beam, the second light beam or the third light beam.

10. The optical measurement assembly of claim 9, wherein, The second light source further comprises a ninth mirror group, a tenth mirror group, an eleventh mirror group, a twelfth mirror group and a thirteenth mirror group, the ninth mirror group collimates the light beam emitted by the first light-emitting component and then the light beam is incident onto the first dichroic sheet, the twelfth mirror group collimates the light beam emitted by the second light-emitting component and then the light beam is incident onto the first dichroic sheet, the thirteenth mirror group collimates the light beam emitted by the third light-emitting component and then the light beam is incident onto the second dichroic sheet, the tenth mirror group collimates the light beam transmitting through the first dichroic sheet and the light beam reflected by the first dichroic sheet and then the light beams are incident onto the second dichroic sheet, and the eleventh mirror group collimates the light beam transmitting through the second dichroic sheet and the light beam reflected by the second dichroic sheet and then the light beams are emitted.

11. The optical measurement assembly of claim 1, wherein, The substrate to be measured is a metal mask plate.

12. The optical measurement assembly of claim 11, wherein, The alignment measurement module further comprises a third light source, the third light source is located between the first beam splitter prism and the substrate to be measured, and is used for illuminating the substrate to be measured.

13. The optical measurement assembly of claim 12, wherein, The third light source is a ring lamp, and the light beam emitted by the second light source and the second detection light both pass through the inner ring surface of the ring lamp.

14. An alignment measurement device, characterized by, It comprises: a base; A gantry structure is arranged on the base; An optical measurement assembly according to any one of claims 1-13 is arranged on the gantry structure, and the gantry structure is configured to drive the optical measurement assembly to move in X, Y and Z directions.

15. An alignment measurement method, characterized by, Comprise: Step S1: providing a substrate to be measured, and placing the substrate to be measured on a workpiece table, wherein the substrate to be measured has a plurality of first alignment marks; Step S2: obtaining a focal plane measurement value corresponding to each of the first alignment marks by using a focal plane measurement module, wherein the focal plane measurement module comprises a first light source, a projection grating and a first camera, the projection grating is provided with at least three light transmission holes, the light beam emitted by the first light source is dispersed into at least three sub-beams after passing through the light transmission holes of the projection grating, the sub-beams are incident on the first alignment marks of the substrate to be measured, and the included angle between each of the sub-beams and the normal line of the substrate to be measured is greater than 45 degrees, at least part of the sub-beams are reflected by the substrate to be measured to form first detection light, and the first detection light is incident into the first camera, and the first camera obtains the focal plane measurement value of the first alignment mark; Step S3: the alignment camera group comprises a second camera and at least one third camera, the field of view of the second camera is different from that of the third camera, the focal plane measurement value corresponding to each of the first alignment marks is compared with the focal plane zero value of the alignment camera group, when the difference between the focal plane measurement value corresponding to each of the first alignment marks and the focal plane zero value of the alignment camera group is less than or equal to a set threshold value, the center coordinate value of all the first alignment marks is obtained by using the alignment camera group; when the difference between the focal plane measurement value of any one of the first alignment marks and the focal plane zero value of the alignment camera group is greater than the set threshold value, the vertical height of the workpiece table is adjusted according to the difference, and step S2 is performed.

16. The alignment measurement method of claim 15, wherein, In step S3, any one of the second camera and the third camera is selected as a specific camera, the focal plane measurement value corresponding to each of the first alignment marks is compared with the focal plane zero value of the specific camera, when the difference between the focal plane measurement value corresponding to each of the first alignment marks and the focal plane zero value of the specific camera is less than or equal to the set threshold value, the center coordinate value of all the first alignment marks is obtained by using the specific camera; when the difference between the focal plane measurement value of any one of the first alignment marks and the focal plane zero value of the specific camera is greater than the set threshold value, the vertical height of the workpiece table is adjusted according to the difference, and step S2 is performed.

17. The method of alignment measurement of claim 16, wherein, The step of selecting any one of the second camera and the third camera as a specific camera comprises: The images of the first alignment marks are obtained by using the second camera and the third camera respectively, the definition of the images obtained by the second camera and the third camera is compared, and the one with better definition is selected as the specific camera.

18. The method of alignment measurement of claim 16, wherein, The focus plane zero position value of the alignment camera set includes a focus plane zero position value of the second camera or the third camera, and the step of obtaining the focus plane zero position value of the second camera or the third camera includes: A reference plate is arranged on the workpiece table, and the reference plate has a plurality of second alignment marks; Vertically moving the reference plate according to a set step, and making the second camera or the third camera obtain an image of the second alignment mark at each vertical position, and comparing the clarity of all images obtained by the second camera or the third camera; Taking the vertical position corresponding to the image with the best clarity in all images obtained by the second camera or the third camera as the optimal vertical position of the second camera or the third camera; Moving the reference plate to the optimal vertical position of the second camera or the third camera, and obtaining a focus plane measurement value corresponding to the second alignment mark by using the focus plane measurement module as the focus plane zero position value of the second camera or the third camera.

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