Alignment mark structure and measurement method applied to wafer optical measurement

Abstract

The application provides an alignment mark structure and a measuring method applied to wafer optical measurement. In the alignment mark structure, the alignment mark structure is arranged in a cutting path of a wafer and is located near an optical measurement target. The alignment mark structure comprises at least two alignment marks, i.e., a first mark and a second mark. The patterns of the first mark and the second mark are non-central symmetric patterns and are different from each other. All the alignment marks are spaced and inlaid between a plurality of measurement pads. The patterns of the first mark and the second mark are at least two layers or more than two layers of non-central symmetric patterns of the wafer medium layer and are made by overlaying. The first mark and the second mark are spaced by several measurement pads. The optical measurement target is located between the first mark and the second mark, or the optical measurement target is located on one side of the first mark or the second mark. The measuring program of the measuring equipment does not need to be frequently reconstructed or modified for different products, so as to facilitate the standardization and automation of the measuring program.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit technology, and in particular to an alignment mark structure and measurement method for wafer optical measurement. Background Technology

[0002] Currently, in semiconductor manufacturing, optical measurement methods are commonly used to measure physical parameters such as film thickness, linewidth, depth, height, and angles within wafers. To ensure measurement accuracy, it is crucial that the probe light spot of the measurement equipment accurately falls on the optical measurement target. The optical measurement target typically refers to one or more measurement pads. Typically, the measurement equipment first positions a specific pattern (also known as a dedicated alignment pattern) on the wafer. The appearance characteristics of this pattern and its relative coordinate position to the optical measurement target are pre-defined in the measurement program. Based on the image information provided in the measurement program, the measurement equipment identifies and locks onto the dedicated alignment pattern on the wafer, using it as a reference. During measurement, alignment is usually required to align the measurement spot with the optical measurement target. However, because the dedicated alignment pattern is typically far from the optical measurement target, significant errors can accumulate during the long-distance movement of the stage from the dedicated alignment pattern to the optical measurement target, causing the spot to deviate from the measurement target. Furthermore, when there is a lack of distinctive patterns near the optical measurement target, the difficulty of identifying the target increases significantly, making it easy to measure the wrong location and thus causing measurement failure. Summary of the Invention

[0003] The purpose of this invention is to provide an alignment mark structure and measurement method for wafer optical measurement, so as to improve the alignment accuracy of optical measurement.

[0004] To achieve the above objectives, the present invention provides an alignment mark structure for wafer optical measurement, used to assist in the alignment of optical measurements in measurement equipment. The alignment mark structure is disposed within the dicing channel of the wafer and located near the optical measurement target. The alignment mark structure includes at least two alignment marks: a first mark and a second mark. The first mark and the second mark are both non-centrosymmetric and have different patterns. These alignment marks are interleaved between multiple measurement pads, forming an integral measurement structure together with all the measurement pads. The patterns of the first mark and the second mark are fabricated by overlaying the same non-centrosymmetric patterns on at least two or more dielectric layers of the wafer, such that the patterns of the alignment marks on the upper and lower layers completely overlap. A plurality of measurement pads are spaced between the first mark and the second mark. The optical measurement target is located between the first mark and the second mark, or the optical measurement target is located on one side of the first mark or the second mark.

[0005] Optionally, in the alignment mark structure, the graphic of the first mark is rotated by a certain angle to be the same as the graphic of the second mark.

[0006] Optionally, in the alignment mark structure, the alignment mark structure further includes: a third mark, wherein the optical measurement target is located between the second mark and the third mark or on the side of the third mark away from the second mark.

[0007] Optionally, in the alignment mark structure, the alignment mark structure further includes a fourth mark, wherein the first mark, the second mark, the third mark and the fourth mark are formed by different rotation angles of the same non-centrosymmetric graphic.

[0008] Optionally, in the alignment mark structure, the third mark and the fourth mark are composed of a combination of regular graphics of a preset small size.

[0009] Optionally, in the alignment mark structure, the spacing between the first mark and the second mark is approximately the field of view of the alignment magnification of the measuring device, and the spacing between the first mark and the second mark is in the range of 0.2mm to 2mm.

[0010] Optionally, in the alignment mark structure, the first mark and the second mark are composed of a combination of regular graphics of a preset small size.

[0011] Optionally, the width of the pattern lines inside the first mark and the second mark is in the range of 1μm to 20μm, and there are no other patterns within a range of 5μm to 10μm around the first mark and the second mark.

[0012] Based on the same inventive concept, the present invention also provides a measurement method for wafer optical measurement, comprising: providing a wafer having a dicing channel, wherein a dedicated alignment pattern and an alignment mark structure are formed within the dicing channel, the dedicated alignment pattern, the alignment mark structure, and the optical measurement target are all located within the same exposure unit, and the optical measurement target includes one or more measurement pads; performing coarse alignment on the wafer using the dedicated alignment pattern, such that the dedicated alignment pattern is located within the field of view of the alignment magnification of the measurement device; performing fine alignment on the wafer using the first mark or the second mark, such that the first mark or the second mark is located within the field of view of the alignment magnification of the measurement device, wherein the spot of the measurement device is completely aligned with the optical measurement target, so as to measure the film thickness or size of the optical measurement target.

[0013] Optionally, in the measurement method, the exposure unit includes a plurality of positive chip regions arranged in an array and the dicing channels located between adjacent positive chip regions; the dedicated alignment pattern is located at the apex of each exposure unit.

[0014] In the alignment mark structure for wafer optical measurement provided by this invention, the alignment mark structure is disposed within the wafer dicing channel and near the optical measurement target. The alignment mark structure includes at least two alignment marks: a first mark and a second mark. The first mark and the second mark have non-centrosymmetric and different patterns. All alignment marks are interleaved and embedded between multiple measurement pads, forming an integral measurement structure together with all the measurement pads. The patterns of the first mark and the second mark are fabricated by overlaying the same non-centrosymmetric patterns on at least two or more wafer dielectric layers, so that the patterns of the alignment marks on the upper and lower layers are as perfectly overlapping as possible. Several measurement pads are spaced between the first mark and the second mark. The optical measurement target is located between the first mark and the second mark, or the optical measurement target is located on one side of the first mark or the second mark. Thus, during wafer optical measurement, the first mark or the second mark can achieve precise alignment of the optical measurement target, ensuring that the light spot is completely aligned with the optical measurement target, thereby improving the measurement alignment accuracy. Furthermore, the alignment mark structure can be used on different products without the need for frequent reconstruction or modification of measurement programs for different products, which facilitates the standardization and automation of measurement programs. Attached Figure Description

[0015] Figure 1 This is a top view of the alignment mark structure on a wafer provided in an embodiment of the present invention.

[0016] Figure 2 This is a top view of an alignment mark structure provided in an embodiment of the present invention.

[0017] Figure 3 This is a top view of an alignment mark structure provided in another embodiment of the present invention.

[0018] Figure 4 This is a top view of the first mark of the alignment mark structure provided in an embodiment of the present invention.

[0019] Figure 5 This is a top view of the first mark of the alignment mark structure provided in another embodiment of the present invention.

[0020] Figure 6 This is a top view of the first mark of the alignment mark structure provided in another embodiment of the present invention.

[0021] Figure 7 This is a schematic flowchart of the wafer optical measurement method provided in an embodiment of the present invention.

[0022] Figure 8 This is a top view of the wafer in the measurement method of wafer optical measurement provided in the embodiment of the present invention.

[0023] The reference numerals in the attached figures are explained as follows: 100 - wafer; 110 - dicing track; 120 - positive chip area; 200 - alignment mark structure; 210 - first mark; 211 - regular pattern; 220 - second mark; 230 - third mark; 240 - fourth mark; 250 - measurement pad; 260 - optical measurement target; 300 - special alignment pattern. Detailed Implementation

[0024] The alignment mark structure and measurement method for wafer optical measurement proposed in this invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of this 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 this invention.

[0025] Figure 1 This is a top view of the alignment mark structure on a wafer provided in an embodiment of the present invention. Figure 2 This is a top view of an alignment mark structure provided in an embodiment of the present invention. (Reference) Figure 1 and combined Figure 2 As shown, this embodiment provides an alignment mark structure 200 for optical measurement of wafer 100, used to assist in the alignment of the optical measurement target 260 of the measurement equipment. The alignment mark structure 200 is disposed within the dicing channel 110 of the wafer 100 and located near the optical measurement target 260. The alignment mark structure 200 includes at least two alignment marks.

[0026] like Figure 2 As shown, in some embodiments, the alignment mark structure 200 includes two alignment marks, namely a first mark 210 and a second mark 220. The first mark 210 and the second mark 220 are non-centrally symmetrical and have different shapes. All alignment marks are interspersed between the measuring pads 250, forming an integral measurement structure together with all the measuring pads 250. In this way, when aligning through the alignment mark structure 200, the light spot can be reliably aligned with the optical measurement target 260, improving the alignment accuracy and avoiding measurement at the wrong position.

[0027] In this embodiment, the patterns of the first mark 210 and the second mark 220 are fabricated by overlaying the same non-centrally symmetrical patterns on at least two or more dielectric layers of the wafer 100, so that the patterns of the alignment marks on the upper and lower layers overlap as completely as possible. That is, the projections of the first mark 210 in each dielectric layer completely overlap, and the projections of the second mark 220 in each dielectric layer completely overlap.

[0028] It should be noted that, due to the translucency of the dielectric layer, if the patterns of the alignment marks on the upper layer and the lower layer are not perfectly aligned and are instead misaligned, a cluttered pattern will appear in the field of view of the measuring device. This will prevent accurate identification of the first mark 210 or the second mark 220, leading to inaccurate alignment. In this embodiment, the patterns of the first mark 210 and the second mark 220 are both made by overlaying identical non-centrally symmetrical patterns. The outlines of the first mark 210 or the second mark 220 on each layer completely overlap, thus avoiding the cluttered pattern in the field of view of the measuring device and improving the clarity of the first mark 210 and the second mark 220.

[0029] For example, such as Figure 2 As shown, several similar measuring pads 250 are spaced between the first mark 210 and the second mark 220. The first mark 210 and the second mark 220 are located within the field of view of the alignment magnification of the measuring device, and the optical measurement target 260 is located between the first mark 210 and the second mark 220. During optical measurement, the field of view of the alignment magnification of the measuring device captures the uniquely shaped first mark 210 or second mark 220. By analyzing the relative positional relationship between the first mark 210 and the second mark 220 and the optical measurement target 260, the optical measurement target 260 can be effectively identified, thereby accurately locating the optical measurement target 260 and effectively reducing or avoiding alignment deviation problems during the optical measurement process.

[0030] The distance between the first mark 210 and the second mark 220 is approximately the size of the field of view of the alignment magnification of the measuring device, and the distance between the first mark 210 and the second mark 220 is in the range of 0.2mm to 2mm.

[0031] For example, such as Figure 3As shown, there are several similar measuring pads 250 spaced between the first mark 210 and the second mark 220. The first mark 210 or the second mark 220 is identified within the field of view of the alignment magnification of the measuring device, and the optical measuring target 260 is accurately positioned by the relative positional relationship between the first mark 210, the second mark 220 and the optical measuring target 260. The optical measuring target 260 is located between the first mark 210 and the second mark 220, or the optical measuring target 260 is located on one side of the first mark 210 or the second mark 220, that is, the optical measuring target 260 is located on the side of the second mark 220 away from the first mark 210 or on the side of the first mark 210 away from the second mark 220.

[0032] The measuring pads 250 spaced between the first mark 210 and the second mark 220 may be, for example, three, four, five, or six measuring pads 250. Figure 2 and Figure 3 The example provided is that two or four measuring pads 250 are provided between the first mark 210 and the second mark 220.

[0033] In this embodiment, the graphic of the first mark 210 is rotated by a certain angle and becomes the same as the graphic of the second mark 220. For example, the graphic of the first mark 210 is rotated by 90° and becomes the same as the graphic of the second mark 220. This helps to simplify the manufacturing process of the alignment mark structure 200, while ensuring that the first mark 210 and the second mark 220 can be clearly distinguished and will not be confused with each other.

[0034] In this embodiment, the spacing between the first mark 210 and the second mark 220 is in the range of 0.2mm to 2mm, for example, 0.3mm, 0.5mm, 1mm, or 1.5mm. If the spacing is too small, the pattern density of the first mark 210 and the second mark 220 will be too high, wasting the surface area of ​​the wafer 100. If the spacing is too large, it may result in a lack of suitable marks near the optical measurement target 260. Therefore, in this embodiment, the spacing between the first mark 210 and the second mark 220 is in the range of 0.2mm to 2mm to avoid wasting the surface area of ​​the wafer 100 and to ensure that there are suitable marks near the optical measurement target 260.

[0035] In some embodiments, such as Figure 3As shown, the alignment mark structure 200 also includes a third mark 230, that is, the alignment mark structure 200 includes three alignment marks. The optical measurement target 260 can be located to the right of the second mark 220. The optical measurement target 260 being located to the right of the second mark 220 means that the optical measurement target 260 is located between the second mark 220 and the third mark 230.

[0036] In other embodiments, the optical measurement target 260 may be located on the side of the third mark 230 away from the second mark 220, that is, the optical measurement target 260 may be located on the right side of the third mark 230.

[0037] In this embodiment, the distance between the first mark 210 and the second mark 220 is approximately the size of the field of view of the alignment magnification of the measuring device, so that the first mark 210 and the second mark 220 are located within the field of view of the alignment magnification of the measuring device.

[0038] In some embodiments, such as Figure 3 As shown, the alignment mark structure 200 also includes a fourth mark 240, meaning the alignment mark structure 200 comprises four alignment marks. The first mark 210, the second mark 220, the third mark 230, and the fourth mark 240 are formed by rotating the same non-centrosymmetric graphic by different angles. For example, the first mark 210 is inverted T-shaped, the second mark 220 is formed by rotating the graphic of the first mark 210 by 90°, the third mark 230 is formed by rotating the graphic of the first mark 210 by 180°, and the fourth mark 240 is formed by rotating the graphic of the first mark 210 by 270°. This ensures that no marks of the same shape appear within the large field of view of the measuring device, improving the contrast of the marks and thus facilitating the identification by the measuring device and preventing the measuring device from picking up incorrect marks.

[0039] It should be noted that, Figure 2 and Figure 3 The first mark 210, the second mark 220, the third mark 230 and the fourth mark 240 are illustrated with a T-shape as an example, but their shapes are not limited to the above example. Other shapes that can be recognized by the measuring device can also be used, such as F-shape or mountain shape.

[0040] In this embodiment, the overall size of the first mark 210, the second mark 220, the third mark 230 and the fourth mark 240 can be equal to or greater than 50um × 50um.

[0041] like Figure 4As shown, the line width W of the inner lines of the first mark 210, the second mark 220, the third mark 230 and the fourth mark 240 is 1μm to 20μm, so as to ensure that the inner lines of the first mark 210, the second mark 220, the third mark 230 and the fourth mark 240 are relatively wide, and there are no other patterns within a 5μm to 10μm range around the first mark and the second mark, so that they can have good clarity and recognition in the optical field of view of the measuring device.

[0042] like Figure 5 As shown, due to the limitations of the wafer product design rule, when it is not allowed to use internal lines with a larger width, the graphics of the first mark 210, the second mark 220, the third mark 230 and the fourth mark 240 can be combined by splicing together the pre-set small-sized regular graphics 211 to meet the product design rule requirements.

[0043] In some embodiments, such as Figure 5 As shown, the shape of the preset small-sized regular graphic 211 can be circular, and the spacing between adjacent regular graphics 211 can be the same, so that all the regular graphics 211 in the first mark 210, the second mark 220, the third mark 230 and the fourth mark 240 are evenly distributed.

[0044] In some embodiments, such as Figure 6 As shown, the shape of the preset small-sized regular graphic 211 can be rectangular, and the spacing between adjacent regular graphics 211 can be the same, so that all regular graphics 211 in the first mark 210, the second mark 220, the third mark 230 and the fourth mark 240 are evenly distributed.

[0045] It should be noted that the shape of the preset small-sized regular graphic 211 is not limited to rectangles and circles, but can also be other regular graphics known to those skilled in the art.

[0046] Furthermore, the alignment mark structure 200 of this embodiment can be placed on wafers 100 of different specifications or on different products, without the need to frequently rebuild or modify the measurement program of the measurement equipment for different products, which facilitates the standardization and automation of the measurement equipment program.

[0047] Figure 7 This is a schematic flowchart of the wafer optical measurement method provided in an embodiment of the present invention. Figure 7As shown, this embodiment provides a measurement method for wafer optical measurement, including: Step S1: providing a wafer, the wafer having a dicing channel, a dedicated alignment pattern and an alignment mark structure formed within the dicing channel, the dedicated alignment pattern, the alignment mark structure and the optical measurement target all being located within the same exposure unit, the optical measurement target including one or more measurement pads; Step S2: performing coarse alignment on the wafer using the dedicated alignment pattern, so that the dedicated alignment pattern is within the field of view of the alignment magnification of the measurement device; Step S3: performing fine alignment on the wafer using the first mark or the second mark, so that the first mark or the second mark is within the field of view of the alignment magnification of the measurement device, and making the light spot of the measurement device completely aligned with the optical measurement target, so as to measure the film thickness or size of the optical measurement target.

[0048] The measurement method for wafer optical measurement provided in this embodiment will be described in more detail below.

[0049] First, execute step S1, as follows: Figure 8 As shown, a wafer 100 is provided, the wafer 100 is provided with a dicing channel 110, a dedicated alignment pattern 300 and an alignment mark structure 200 are formed in the dicing channel 110, the dedicated alignment pattern 300 and the alignment mark structure 200 are located in the same exposure unit as the optical measurement target 260, and the alignment mark structure is located near the optical measurement target 260.

[0050] Specifically, the exposure unit includes a plurality of prime dies 120 arranged in an array and cleaving channels 110 located between adjacent prime dies 120; the dedicated alignment pattern 300 is located at the apex of each exposure unit.

[0051] In this embodiment, the dedicated alignment pattern 300 is a coarse alignment mark used for coarse alignment of the wafer 100. For example... Figure 2 As shown, the first mark 210 and the second mark 220 in the alignment mark structure 200 are fine alignment marks used to perform fine alignment on the wafer 100.

[0052] In some embodiments, a first mark 210 of the alignment mark structure 200 is disposed between the dedicated alignment pattern and the optical measurement target 260. Specifically, when the optical measurement target 260 is located between the first mark 210 and the second mark 220, the first mark 210 is disposed between the dedicated alignment pattern and the optical measurement target 260.

[0053] In some embodiments, the first mark 210 and the second mark 220 of the alignment mark structure 200 are both disposed between the dedicated alignment pattern 300 and the optical measurement target 260. Specifically, when the optical measurement target 260 is located to the right of the second mark 220, the first mark 210 and the second mark 220 are both disposed between the dedicated alignment pattern and the optical measurement target 260.

[0054] Next, step S2 is performed, in which a coarse alignment operation is performed on the wafer 100 using the dedicated alignment pattern 300, so that the dedicated alignment pattern 300 is within the field of view of the alignment magnification of the measurement device. Specifically, during the coarse alignment operation, the measurement device adjusts the position of the wafer 100 by recognizing the dedicated alignment pattern 300, so that the dedicated alignment pattern 300 is completely within the field of view of the alignment magnification of the measurement device.

[0055] Next, step S3 is executed, in which the wafer 100 is precisely aligned with the first mark 210 or the second mark 220 so that the first mark 210 or the second mark 220 is located within the field of view of the alignment magnification of the measurement device, and the spot of the measurement device is fully aligned with the optical measurement target 260 so as to measure the film thickness or size of the optical measurement target 260.

[0056] Specifically, during the precise alignment operation, the measuring device identifies the first mark 210 or the second mark 220 and determines the position of the optical measurement target 260 based on the relative positional relationship between the first mark 210 or the second mark 220 and the optical measurement target 260. This ensures that the light spot of the measuring device is completely aligned with the optical measurement target 260, thereby allowing for film thickness or size measurement of the optical measurement target 260. Since the first mark 210 and the second mark 220 are non-centrally symmetrical and different in shape, they possess unique characteristics within the field of view of the measuring device's alignment magnification. This clearly helps identify surrounding measurement positions, achieving precise alignment of the optical measurement and ensuring the light spot is completely aligned with the optical measurement target 260, thereby improving the measurement alignment accuracy.

[0057] In summary, the alignment mark structure and measurement method for wafer optical measurement provided by this invention are disposed within the wafer dicing channel and near the optical measurement target. The alignment mark structure includes at least two alignment marks: a first mark and a second mark. The first and second marks are non-centrosymmetric and have different patterns. All alignment marks are interleaved between measurement pads, forming a unified measurement structure together with all the measurement pads. The patterns of the first and second marks are fabricated by overlaying the same non-centrosymmetric patterns on at least two or more wafer dielectric layers, ensuring that the patterns of the upper and lower layers overlap as completely as possible. Several similar measurement pads are spaced between the first and second marks. The optical measurement target is located between the first and second marks, or on one side of either the first or second mark. Thus, during wafer optical measurement, precise alignment can be achieved, ensuring the light spot is perfectly aligned with the optical measurement target, thereby improving measurement alignment accuracy. Furthermore, the alignment mark structure can be used on different products without the need to frequently rebuild or modify the measurement program of the measurement equipment for different products, which facilitates the standardization and automation of the measurement equipment program.

[0058] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

[0059] Furthermore, it should be understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. An alignment mark structure for wafer optical measurement, used to assist in the alignment of optical measurement targets in measurement equipment, characterized in that, The alignment mark structure is disposed within the dicing channel of the wafer and located near the optical measurement target. The alignment mark structure includes: At least two alignment marks: a first mark and a second mark, wherein the first mark and the second mark are non-centrosymmetric and different in shape, and all the alignment marks are interleaved between multiple measurement pads to form an integral measurement structure together with all the measurement pads. The first mark and the second mark are fabricated by overlaying the same non-centrosymmetric pattern on the dielectric layers of the wafer of at least two layers, so that the patterns of the alignment marks on the upper and lower layers completely overlap. The measuring pads are spaced apart between the first mark and the second mark, and the optical measurement target is located between the first mark and the second mark, or the optical measurement target is located on one side of the first mark or the second mark.

2. The alignment mark structure as described in claim 1, characterized in that, The graphic of the first mark becomes identical to the graphic of the second mark after being rotated by a certain angle.

3. The alignment mark structure as described in claim 1, characterized in that, The alignment mark structure further includes a third mark, wherein the optical measurement target is located between the second mark and the third mark or on the side of the third mark away from the second mark.

4. The alignment mark structure as described in claim 3, characterized in that, The alignment mark structure further includes a fourth mark, wherein the first mark, the second mark, the third mark and the fourth mark are formed by different rotation angles of the same non-centrosymmetric graphic.

5. The alignment mark structure as described in claim 4, characterized in that, The third and fourth marks are composed of a combination of regular graphics of a preset small size.

6. The alignment mark structure as described in claim 1, characterized in that, The distance between the first mark and the second mark is approximately the size of the field of view of the alignment magnification of the measuring device, and the distance between the first mark and the second mark is in the range of 0.2 mm to 2 mm.

7. The alignment mark structure as described in claim 1, characterized in that, The graphics of the first mark and the second mark are composed of a combination of regular graphics of a preset small size.

8. The alignment mark structure as described in claim 1, characterized in that, The width of the pattern lines inside the first mark and the second mark is in the range of 1μm to 20μm, and there are no other patterns in the range of 5μm to 10μm around the first mark and the second mark.

9. A measurement method for wafer optical measurement, characterized in that, include: A wafer is provided, the wafer having a dicing channel, a dedicated alignment pattern and an alignment mark structure as described in claim 1 are formed in the dicing channel, the dedicated alignment pattern, the alignment mark structure and the optical measurement target are all located in the same exposure unit, the optical measurement target including one or more measurement pads; Coarse alignment of the wafer is performed using the dedicated alignment pattern, such that the dedicated alignment pattern is within the field of view of the alignment magnification of the measurement device; The wafer is precisely aligned using the first mark or the second mark so that the first mark or the second mark is within the field of view of the alignment magnification of the measurement device, and the spot of the measurement device is fully aligned with the optical measurement target to measure the film thickness or size of the optical measurement target.

10. The measurement method as described in claim 9, characterized in that, The exposure unit includes a plurality of positive chip regions arranged in an array and the cutting track located between adjacent positive chip regions; the dedicated alignment pattern is located at the apex of each exposure unit.

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