Metrology method and lithography process control system
By measuring the critical dimension deviations at the periphery and center of the wafer exposure area and adjusting the photomask parameters, the problem of inaccurate critical dimension measurement in existing technologies is solved, thereby improving the accuracy and consistency of the photolithography process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NAN YA TECH
- Filing Date
- 2022-11-04
- Publication Date
- 2026-06-09
AI Technical Summary
Existing technologies struggle to accurately measure the critical dimensions of feature patterns and reduce critical dimension deviations, especially as wafers shrink and errors become even more difficult to control.
By measuring the peripheral and central critical size deviations of multiple exposure areas on the wafer, it is determined whether the deviation values are within a predetermined range, the main deviation direction and amount of change are evaluated, and the photomask parameters are adjusted to correct the error.
This enables more accurate measurement of critical dimensions and reduces errors, thereby improving the precision and consistency of the photolithography process.
Smart Images
Figure CN117666291B_ABST
Abstract
Description
Technical Field
[0001] This case relates to a measurement method, and more particularly to a measurement method for measuring critical dimensions and a photolithography process control system. Background Technology
[0002] In current technology, as chip size shrinks, how to more accurately measure the critical dimensions of feature patterns and correspondingly reduce the deviation of critical dimensions is an important issue in this field. Summary of the Invention
[0003] This disclosure provides a measurement method. The measurement method includes the following steps: A plurality of exposure regions are formed on a wafer according to a photomask. Peripheral critical dimensions of each of the plurality of exposure regions are measured at corresponding peripheral sampling positions within a portion of the plurality of exposure regions, and central critical dimensions of each of the plurality of exposure regions are measured at corresponding central sampling positions within the plurality of exposure regions. A deviation value between the peripheral critical dimension and the central critical dimension of each of the plurality of exposure regions in the portion is calculated. It is determined whether the deviation value of each of the plurality of exposure regions in the portion is within a deviation range. If the deviation value of each of the plurality of exposure regions is within the deviation range, the amount of deviation change of one of the plurality of exposure regions in a major deviation direction is evaluated. The parameters of the photomask are adjusted based on the amount of deviation change of one of the plurality of exposure regions in the major deviation direction.
[0004] In some embodiments, the evaluation step includes the following steps: Selecting a first edge region and a second edge region from one of the plurality of exposure regions; Measuring a plurality of first critical dimensions along a direction in the first edge region and measuring a plurality of second critical dimensions along the direction in the second edge region; Generating a first comparison result based on a first trend of variation of the plurality of first critical dimensions along the direction and a second trend of variation of the plurality of second critical dimensions along the direction; Evaluating the principal deviation direction of the plurality of exposure regions based on the first comparison result; Evaluating the amount of deviation change of the plurality of exposure regions along the principal deviation direction based on one of the first trend of variation and the second trend of variation.
[0005] In some embodiments, the first edge region is the region selected along the first edge of the subject in the plurality of exposure regions along the vertical direction from the center point of the subject in the plurality of exposure regions, and the second edge region is the region selected along the second edge of the subject in the plurality of exposure regions along the horizontal direction from the center point of the subject in the plurality of exposure regions.
[0006] In some embodiments, if the first comparison result is that the first trend of change is greater than the second trend of change, the main deviation direction of the plurality of exposure areas is determined to be the vertical direction, and the amount of deviation change along the vertical direction is evaluated based on the first trend of change; if the first comparison result is that the first trend of change is less than the second trend of change, the main deviation direction of the plurality of exposure areas is determined to be the horizontal direction, and the amount of deviation change along the horizontal direction is evaluated based on the second trend of change.
[0007] In some embodiments, a first corner region, a second corner region, a third corner region, and a fourth corner region are selected from the plurality of exposure regions, wherein the first corner region and the second corner region are located on the first diagonal of the plurality of exposure regions, and the third corner region and the fourth corner region are located on the second diagonal of the plurality of exposure regions; a plurality of third critical dimensions, a plurality of fourth critical dimensions, a plurality of fifth critical dimensions, and a plurality of sixth critical dimensions are measured in the first corner region, the second corner region, the third corner region, and the fourth corner region, respectively.
[0008] In some embodiments, the amount of change at a first corner of the first diagonal and the amount of change at a second corner of the second diagonal in the plurality of exposure areas are evaluated based on the plurality of third critical dimensions, the plurality of fourth critical dimensions, the plurality of fifth critical dimensions and the plurality of sixth critical dimensions.
[0009] In some embodiments, the photomask is adjusted based on the main deviation direction, the deviation change, the first corner change, and the second corner change.
[0010] In some embodiments, each of the plurality of exposure areas is a pattern composed of a plurality of diagonal straight lines.
[0011] In some embodiments, the deviation range is less than one-twentieth of the target critical size.
[0012] This disclosure provides a photolithography process control system. The photolithography process control system includes a photolithography apparatus, a metrology unit, and a processor. The photolithography apparatus is used to form multiple exposure regions on a wafer based on a photomask. The metrology unit measures the peripheral critical dimensions of each of the multiple exposure regions at corresponding peripheral sampling positions within a portion of the multiple exposure regions, and measures the central critical dimensions of each of the multiple exposure regions at corresponding central sampling positions within the portion of the multiple exposure regions. The processor is used to perform the following steps: Calculate the deviation value between the peripheral critical dimension and the central critical dimension of each of the multiple exposure regions in the portion. Determine whether the deviation value of each of the multiple exposure regions in the portion is within a deviation range. If the deviation value of each of the multiple exposure regions is within the deviation range, evaluate the amount of deviation change of one of the multiple exposure regions in a major deviation direction. Adjust the parameters of the photomask based on the amount of deviation change of one of the multiple exposure regions in the major deviation direction.
[0013] In summary, the measurement method and photolithography process control system disclosed in this document utilize a processor to determine whether the deviation between the peripheral critical size and the central critical size of each of the multiple exposure areas is within the deviation range, thereby determining whether the error factor of the critical size is affected by each exposure, and thereby correcting the parameters of the photomask to reduce the critical size deviation. Attached Figure Description
[0014] To make the above and other objects, features, advantages and embodiments of this disclosure more apparent and understandable, the accompanying drawings are described below:
[0015] Figure 1 This is a schematic diagram of a photolithography process control system according to an embodiment of the present disclosure.
[0016] Figure 2 This is a flowchart of a measurement method according to an embodiment of the present disclosure.
[0017] Figure 3 This is a schematic diagram of a wafer according to an embodiment of the present disclosure.
[0018] Figure 4 This is a schematic diagram of the deviation range of an embodiment of this disclosure.
[0019] Figure 5A This disclosure provides an embodiment of the invention. Figure 2 A schematic diagram of step S250 in the measurement method.
[0020] Figure 5B This disclosure provides an embodiment of the invention. Figure 5A A schematic diagram of steps S254 and S255 in the process.
[0021] Figure 5C This disclosure provides an embodiment of the invention. Figure 2 A schematic diagram of step S260 in the measurement method.
[0022] Figure 6 This disclosure provides an embodiment of the invention. Figure 1 A schematic diagram of the exposure area in a wafer.
[0023] Figure 7 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the first edge region in the exposure area.
[0024] Figure 8 This disclosure provides an embodiment of the invention. Figure 7 A schematic diagram of the critical dimensions of the sampling location in the first edge region.
[0025] Figure 9 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the second edge region RLFT in the exposure area.
[0026] Figure 10 This disclosure provides an embodiment of the invention. Figure 9 A schematic diagram of the critical dimensions of the sampling location in the second edge region.
[0027] Figure 11 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the first corner area of the exposure area.
[0028] Figure 12 This disclosure provides an embodiment of the invention. Figure 11 A schematic diagram of the critical dimensions of the sampling location in the first corner region.
[0029] Figure 13 This disclosure provides an embodiment of the invention. Figure 6 A diagram of the fourth corner area in the exposure area.
[0030] Figure 14 This disclosure provides an embodiment of the invention. Figure 13 A schematic diagram of the critical size of the sampling location in the fourth corner region.
[0031] Figure 15 This disclosure provides an embodiment of the invention. Figure 6 A diagram of the third corner area in the exposure area.
[0032] Figure 16 This disclosure provides an embodiment of the invention. Figure 15 A schematic diagram of the critical dimensions of the sampling location in the third corner region.
[0033] Figure 17 This disclosure provides an embodiment of the invention. Figure 6A schematic diagram of the second corner area of the exposure area.
[0034] Figure 18 This disclosure provides an embodiment of the invention. Figure 15 A schematic diagram of the critical dimensions of the sampling location in the second corner region. Detailed Implementation
[0035] The following detailed description of embodiments, accompanied by the accompanying drawings, aims to provide a better understanding of the present invention. However, the provided embodiments are not intended to limit the scope of the present invention, and the description of structural operations is not intended to limit the order of their execution. Any structure resulting from the recombination of elements, producing a device with equivalent functionality, falls within the scope of this invention. Furthermore, in accordance with industry standards and common practice, the accompanying drawings are for illustrative purposes only and are not drawn to their original dimensions. In fact, the dimensions of various features may be arbitrarily increased or decreased for ease of explanation. In the following description, the same elements will be labeled with the same symbols for ease of understanding.
[0036] The indexes 1 to n in the component and signal numbers used in this specification and drawings are for convenience of referring to individual components and signals, and are not intended to limit the number of the aforementioned components and signals to a specific number. In this specification and drawings, if a component or signal number is used without specifying its index, it means that the component or signal number refers to any unspecified component or signal within the corresponding component or signal group.
[0037] Furthermore, the terms "comprising," "including," "having," "containing," etc., used in this document are all open-ended terms, meaning "including but not limited to." Additionally, the term "and / or" as used in this document includes any one or more of the related listed items and all combinations thereof.
[0038] In this document, when an element is referred to as a “connection” or “coupled,” it may mean an “electrical connection” or “electrical coupling.” “Connection” or “coupled” can also be used to indicate the operation or interaction between two or more elements. Furthermore, although terms such as “first,” “second,” etc., are used in this document to describe different elements, these terms are only used to distinguish elements or operations described using the same technical terminology.
[0039] Please see Figure 1 , Figure 1 This is a schematic diagram of a photolithography process control system 100 according to an embodiment of this disclosure. Figure 1As shown, the photolithography process control system 100 includes a photolithography process equipment 110, a controller 120, and a metrology equipment 130. The controller 120 includes a processor 122 and a memory 124. The memory 124 is used to store measurement data from the metrology equipment 130 or process parameters of the photolithography process equipment 110 (e.g., mask pattern fabrication parameters). In some embodiments, the processor 122 is used to retrieve measurement data from the memory 124 or adjust the mask pattern fabrication parameters. In some embodiments, the processor 122 is communicatively / electrically coupled to the photolithography process equipment 110 and the metrology equipment 130.
[0040] In some embodiments, the photolithography equipment 110 is used to perform processes such as composition coating, soft baking, exposure, post-exposure baking, development, and hard baking on the wafer 10. In some embodiments, after hard baking the wafer 10, the measurement equipment 130 is used to measure the critical dimensions of the exposed areas on the wafer 10.
[0041] In some embodiments, if the critical dimension measured by the measurement equipment 130 is within an acceptable error range, the wafer 10 will be subjected to a subsequent etching process; if the measured critical dimension exceeds a preset error range, the resist layer on the wafer 10 will be removed and the wafer 10 will be cleaned before returning to resist layer coating and the parameters of the exposure process will be adjusted accordingly.
[0042] In some embodiments, the measuring instrument 130 may be implemented by a scanning electron microscope or by an optical measuring instrument. In other embodiments, the measuring instrument may be implemented by other devices capable of measuring critical dimensions. Therefore, this invention is not limited thereto.
[0043] Please see Figures 2 to 4 , Figure 2 This is a flowchart of a measurement method 200 according to an embodiment of the present disclosure. Figure 3 This is a schematic diagram of a wafer 10 according to an embodiment of the present disclosure. Figure 4 This is a schematic diagram of the deviation range INT according to an embodiment of this disclosure. Figure 2 As shown, measurement method 200 includes steps S210 to S270.
[0044] It is worth noting that, since the wafer 10 process in this case can be implemented using the wafer process of a dynamic random access memory chip, the feature pattern FP of the exposure area 12 is a pattern composed of multiple diagonal straight lines.
[0045] In step S210, a plurality of exposure areas are formed on the wafer according to a photomask. In some embodiments, each of the plurality of exposure areas is formed by the same photomask through multiple identical exposure processes. In other words, the wafer 10 has a plurality of exposure areas 11 (exposure patterns) formed by the same photomask through multiple identical exposure processes, such as... Figure 3As shown. In some embodiments, step S210 may be performed by photolithography equipment 110.
[0046] In step S220, the deviation between the peripheral critical dimension and the central critical dimension of each of the plurality of exposure areas in a portion is measured and calculated. Specifically, the peripheral critical dimension of each of the plurality of exposure areas 11 is measured by the measuring instrument 130 at corresponding peripheral sampling positions within the plurality of exposure areas 11 in a portion, and the central critical dimension of each of the plurality of exposure areas 11 is measured by the measuring instrument 130 at corresponding central sampling positions within the plurality of exposure areas 11 in the portion.
[0047] For example, the measuring instrument 130 measures the peripheral critical dimension of the exposure area 12 at sampling position E1 around the periphery of the exposure area 12, and measures the central critical dimension of the exposure area 12 at sampling position C1 around the center of the exposure area 12. Similarly, the measuring instrument 130 measures the peripheral critical dimension of the exposure area 13 at sampling position E2 around the periphery of the exposure area 13, and measures the central critical dimension of the exposure area 13 at sampling position C2 around the center of the exposure area 13.
[0048] Furthermore, the processor 122 calculates the deviation value between the peripheral critical dimension and the central critical dimension of each of the plurality of exposure regions (e.g., exposure regions 12 and 13). For example, the processor 122 calculates the deviation value CDD1 between the peripheral critical dimension and the central critical dimension of exposure region 12, and calculates the deviation value CDD2 between the peripheral critical dimension and the central critical dimension of exposure region 13, as follows. Figure 4 As shown. Among them, Figure 4 The vertical axis represents the deviation ER between the peripheral critical dimension and the central critical dimension. Figure 4 The horizontal axis represents the wafer radius R, which is used to distinguish the exposure areas at different locations.
[0049] In step S230, it is determined whether the deviation value of each of the plurality of exposed areas of the portion is within the deviation range. In some embodiments, the range of the deviation range INT can be one-twentieth of the target critical size. For example, if the target critical size is 30 nanometers, the deviation range INT is within 0.75 nanometers before and after the average deviation BIAS. For example, if the average deviation BIAS is 2 nanometers, the deviation range INT is in the range of 1.25 to 2.75.
[0050] If the deviation values of the multiple exposure areas 11 are not within the deviation range INT, it means that the changes of the multiple exposure areas 11 do not have the same / similar trend and are less related to the parameter conditions of each exposure process. Then proceed to step S240 to end the current process.
[0051] If the deviation values of the plurality of exposure regions 11 (e.g., deviation values CDD1 and CDD2) are within the deviation range INT, it indicates that the changes in the plurality of exposure regions 11 have the same / similar trend and are more correlated with the parameter conditions of each exposure process, but less correlated with the overall unevenness of the wafer 10. Step S250 is then followed by evaluating the amount of deviation change of one of the plurality of exposure regions 11 in the main deviation direction. Furthermore, in the subsequent step S260, the amount of change of the plurality of exposure regions (e.g., exposure regions 12 and 13) along the diagonal is evaluated. Thus, in step S270, the parameters of the photomask can be adjusted accordingly. The detailed operation of steps S250 and S260 will be described in subsequent embodiments.
[0052] For a better understanding of the following embodiments, please refer to the following documents: Figures 1 to 17 . Figure 5A This disclosure provides an embodiment of the invention. Figure 2 A schematic diagram of step S250 in measurement method 200. Figure 5B This disclosure provides an embodiment of the invention. Figure 5A A schematic diagram of steps S254 and S255 in the process. Figure 5C This disclosure provides an embodiment of the invention. Figure 2 A schematic diagram of step S260 in measurement method 200.
[0053] Figure 6 This disclosure provides an embodiment of the invention. Figure 1 A schematic diagram of the exposure area 12 in the wafer 10. Figure 7 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the first edge region RBOT in the exposure area 12. Figure 8 This disclosure provides an embodiment of the invention. Figure 7 A schematic diagram of the critical dimensions of the sampling locations BOT1 to BOT15 in the first edge region RBOT. Figure 9 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the second edge region RLFT in the exposure area 12. Figure 10 This disclosure provides an embodiment of the invention. Figure 9 A schematic diagram of the critical dimensions of the sampling positions LEF1 to LEF15 of the second edge region RLFT.
[0054] Figure 11 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the first corner region RTL in the exposure area 12. Figure 12 This disclosure provides an embodiment of the invention. Figure 11 A schematic diagram of the critical dimensions of the sampling positions TL1 to TL15 of the first corner region RTL. Figure 13This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the fourth corner region RBL in the exposure area 12. Figure 14 This disclosure provides an embodiment of the invention. Figure 13 A schematic diagram of the critical dimensions of the sampling positions BL1 to BL20 in the fourth corner region RBL.
[0055] Figure 15 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the third corner region RTR in the exposure area 12. Figure 16 This disclosure provides an embodiment of the invention. Figure 15 A schematic diagram of the critical dimensions of the sampling positions TR1 to TR20 of the third corner region RTR. Figure 17 This disclosure provides an embodiment of the invention. Figure 6 A schematic diagram of the second corner region RBR in the exposure area 12. Figure 18 This disclosure provides an embodiment of the invention. Figure 15 A schematic diagram of the critical dimensions of the sampling positions BR1 to BR15 in the second corner region RBR.
[0056] like Figure 5A As shown, step S250 includes steps S251 to S255. For example... Figure 5B As shown, step S254 includes steps S312, S314, S318, and S320, and step S255 includes steps S316 and S322. For example... Figure 5C As shown, step S260 includes steps S261 to S263.
[0057] In step S251, a first edge region and a second edge region are selected from one of the plurality of exposure regions. For example, from... Figure 6 The exposure area 12 is selected from a first edge region RBOT and a second edge region RLET. The first edge region RBOT is the area selected by the center point Oc of the exposure area 12 along the vertical direction y at the first edge ED1 of the exposure area 12, and the second edge region RLET is the area selected by the center point Oc of the exposure area 12 along the horizontal direction x at the second edge ED2 of the exposure area 12.
[0058] In step S252, multiple first critical dimensions are measured along the direction in the first edge region, and multiple second critical dimensions are measured along the direction in the second edge region. Figure 7 as well as Figure 8 As shown, the measuring machine 130 measures the plurality of first critical dimensions in the first edge region RBOT along direction D1 via path P1~P3 from sampling positions BOT1~BOT15. Figure 9 as well as Figure 10As shown, the measuring machine 130 measures the plurality of second critical dimensions along direction D1 in the second edge region RLFT from sampling position LEF1 to LEF15 via path P4 to P6.
[0059] It should be noted that the sampling positions BOT1 to BOT15 along paths P1 to P3 can be determined by the measuring instrument 130 based on reference line RL1. The sampling positions LEF1 to LEF15 along paths P4 to P6 can be determined by the measuring instrument 130 based on reference line RL2. In some embodiments, reference lines RL1 and RL2 are determined based on a specific number of characteristic microstructures (e.g., oblique straight lines) on the first edge ED1 and the second edge ED2. Furthermore, in Figure 8 as well as Figure 10 The target values shown represent the numerical values of the target critical size.
[0060] In step S253, a first comparison result is generated based on a first variation trend of the plurality of first critical dimensions along the direction and a second variation trend of the plurality of second critical dimensions along the direction. Furthermore, in step S254, the main deviation direction of the plurality of exposure areas is evaluated based on the first comparison result. Further details can be found in [link to relevant documentation]. Figure 5B Step S254. Step S254 includes steps S312 to S322.
[0061] In step S312, the main deviation direction of the plurality of exposure areas is evaluated based on the first comparison result. If the first comparison result shows that the first trend of change is greater than the second trend of change, proceed to step S314, where the main deviation direction of the plurality of exposure areas is the vertical direction. For example, such as Figure 8 as well as Figure 10 As shown in the embodiment, the first trend of change T BOT1 ~T BOT3 The magnitude / slope of the change is greater than that of the second trend T. LEF1 ~T LEF3 The magnitude / slope of the change. Processor 122 can determine the first trend T. BOT1 ~T BOT3 Greater than the second trend of change T LEF1 ~T LEF3 .
[0062] Due to the first trend of change T BOT1 ~T BOT3 In the first edge region RBOT, the changing trends of the plurality of first critical dimensions along the path P1 to P3 are measured and determined along the direction D1, and the first changing trend T along the path P1 to P3 is determined. BOT1 ~T BOT3Since the deviations of the exposure areas 12 and 11 vary from large to small within a relatively large range, the processor 122 can determine that the main deviation direction of the exposure area 12 is in the vertical direction y with the center point Oc as the reference. Correspondingly, the main deviation directions of the plurality of exposure areas 11 are in the vertical direction y with the center point of each of the plurality of exposure areas 11 as the reference.
[0063] On the other hand, such as Figure 10 As shown, due to the second trend T LEF1 ~T LEF3 The magnitude / slope of the change compared to the first trend T BOT1 ~T BOT3 More gradual, due to the second trend T LEF1 ~T LEF3 In the second edge region RLFT, the change trend of the plurality of second critical dimensions measured along direction D1 along path P4 to P6 indicates that the processor 122 can determine that the main deviation direction of the exposure region 12 is not in the horizontal direction x with the center point Oc as the reference. Correspondingly, the main deviation direction of the plurality of exposure regions 11 is not in the horizontal direction x with the center point of each of the plurality of exposure regions 11 as the reference.
[0064] In step S316, the change in deviation along the vertical direction is evaluated based on the first trend of change. For example, the processor 122 evaluates the change based on the first trend T. BOT1 ~T BOT3 The change in deviation along the vertical direction y is evaluated with the center point Oc as a reference. For example, processor 122 evaluates the first trend of change T. BOT1 The variation from large to small is 38-31 nanometers. In step S272, the parameters of the photomask are adjusted according to the main deviation direction and the amount of deviation change. The processor 122 adjusts the parameters of the photomask corresponding to the first edge region RBOT of the exposure area 12 based on the amount of deviation change (e.g., 38-31 nanometers) along the vertical direction y with the center point Oc as a reference.
[0065] Similarly, in step S318, the main deviation direction of the plurality of exposure areas is evaluated based on the first comparison result. If the first comparison result shows that the first trend of change is less than the second trend of change, proceed to step S320, where the main deviation direction of the plurality of exposure areas is the horizontal direction x. Since steps S318 to S320 are similar to steps S312 to S314, they will not be described again here.
[0066] In step S322, the change in deviation along the horizontal direction is evaluated based on the second trend of change. For example, the processor 122 evaluates the change based on the second trend T. LEF1 ~T LEF3 The change in deviation along the vertical direction x, with the center point Oc as the reference, is evaluated. For example, processor 122 evaluates the second trend T.LEF1 ~T LEF3 The variation, from large to small, is between 36 and 30 nanometers. In step S272, the parameters of the photomask are adjusted based on the main deviation direction and the amount of deviation change. The processor 122 adjusts the parameters of the second edge region RLFT of the photomask corresponding to the exposure area 12 based on the amount of deviation change (e.g., 36-30 nanometers) along the horizontal direction x with the center point Oc as a reference.
[0067] In step S261, a first corner region, a second corner region, a third corner region, and a fourth corner region are selected from the plurality of exposure regions. For example... Figure 6 As shown, the processor 122 controls the measurement equipment 130 to select a first corner region RTL, a second corner region RBR, a third corner region RTR, and a fourth corner region RBL from the plurality of exposure regions 12. The first corner region RTL and the second corner region RBR are located along the first diagonal line from the upper left to the lower right of the plurality of exposure regions 12, and the third corner region RTR and the fourth corner region RBL are located along the second diagonal line from the upper right to the lower left of the exposure region 12.
[0068] In step S262, multiple third critical dimensions, multiple fourth critical dimensions, multiple fifth critical dimensions, and multiple sixth critical dimensions are measured in the first corner region, the second corner region, the third corner region, and the fourth corner region, respectively. Specifically, the multiple third critical dimensions are measured by the measuring machine 130 along direction D1 in the first corner region RT at sampling positions TL1 to TL11 along path P7 to P9, as follows: Figure 11 as well as Figure 12 As shown.
[0069] Multiple fifth critical dimensions measured by the measuring instrument 130 in the third corner region RTR along direction D1, at sampling positions TR1 to TR20 along path P14 to P17, such as... Figure 15 as well as Figure 16 As shown.
[0070] Multiple fourth critical dimensions measured by the measuring machine 130 along direction D1 in the second corner region RBR at sampling positions BR1 to BR15 along path P18 to P20, such as... Figure 17 as well as Figure 18 As shown.
[0071] Multiple sixth critical dimensions are measured by the measuring machine 130 along direction D1 in the fourth corner region RBL, at sampling positions BL1 to BL16 along path P10 to P13, such as... Figure 13 as well as Figure 14 As shown.
[0072] It is important to note that Figure 8 , Figure 10 , Figure 12 , Figure 14 , Figure 16 as well as Figure 18 The vertical axis has a unit length of equal length and its unit of measurement can be expressed in nanometers. Furthermore, sampling positions TL1 to TL11 in paths P7–P9 can be determined by the measuring instrument 130 based on reference line RL3. Sampling positions BR1 to BR11 in paths P18–P20 can be determined by the measuring instrument 130 based on reference line RL6. Sampling positions TR1 to TR20 in paths P14–P17 can be determined by the measuring instrument 130 based on reference line RL5. Sampling positions BL1 to BL20 in paths P10–P13 can be determined by the measuring instrument 130 based on reference line RL4. In some embodiments, reference lines RL3–RL6 are determined based on a specific number of feature microstructures (e.g., oblique straight lines) on the edge of the feature pattern FP. Furthermore, in Figure 12 , Figure 14 , Figure 16 as well as Figure 18 The target values shown represent the numerical values of the target critical size.
[0073] In step S263, the amount of change at the first corner of the first diagonal and the amount of change at the second corner of the second diagonal in the plurality of exposure areas are evaluated based on the plurality of third critical dimensions, the plurality of fourth critical dimensions, the plurality of fifth critical dimensions and the plurality of sixth critical dimensions.
[0074] For example, processor 122 evaluates the corner variation of the first corner region RTL of the exposure area 12 along the first diagonal based on the plurality of third critical dimensions measured from sampling positions TL1 to TL11 (e.g., a variation of 38-37 nanometers in path P8), and processor 122 evaluates the corner variation of the second corner region RBR of the exposure area 12 along the first diagonal based on the plurality of fourth critical dimensions measured from sampling positions BR1 to BR11 (e.g., a variation of 38-32 nanometers in path P18).
[0075] Similarly, processor 122 evaluates the corner variation of the third corner region RTR of the exposure area 12 along the second diagonal based on the plurality of fifth critical dimensions measured from sampling positions TR1 to TR20 (e.g., a variation of 34-38 nm in path P14), and processor 122 evaluates the corner variation of the fourth corner region RBL of the exposure area 12 along the second diagonal based on the plurality of sixth critical dimensions measured from sampling positions BL1 to BL20 (e.g., a variation of 38-34 nm in path P12).
[0076] In some embodiments, the processor 122 is further configured to determine, based on the plurality of third critical dimensions and the plurality of fourth critical dimensions, whether the corner change trends of the first corner region RTL and the second corner region RBR on the first diagonal are symmetrical, and whether the corner change trends of the third corner region RTR and the fourth corner region RBL on the second diagonal are symmetrical. If the processor 122 determines that the corner change trends of the first corner region RTL and the second corner region RBR on the first diagonal are symmetrical, the deviation of the entire exposure area 12 can be evaluated based on the change trends of each region. For example, the critical dimension of the peripheral region in the exposure area 12 is greater than the critical dimension of the central region, or the critical dimension of the central region in the exposure area 12 is greater than the critical dimension of the peripheral region, and the correction parameters of the photomask can be evaluated accordingly.
[0077] In step S274, the parameters of the photomask are adjusted based on the main deviation direction, the amount of deviation change, the amount of change at the first corner, and the amount of change at the second corner. The processor 122 controls the lithography equipment 110 to adjust the parameters of the photomask based on the main deviation direction, the amount of deviation change, the amount of change at the first corner, and the amount of change at the second corner.
[0078] In summary, the measurement method 200 of this disclosure determines, through a processor, whether the deviation between the peripheral critical dimension and the central critical dimension of each of the plurality of exposure regions 11 is within the deviation range INT, thereby determining whether the error factor of the critical dimension is affected by each exposure. Furthermore, the measurement method 200 of this disclosure uses measurements of the critical dimensions of a single exposure region 12 on the wafer 10 in the peripheral and corner regions to evaluate the main deviation direction and deviation variation of the exposure region 12, and adjusts the photomask parameters based on the main deviation direction and deviation variation. Thus, the measurement method 200 of this disclosure and the photolithography process control system 100 can more accurately correct the photomask parameters based on the critical dimensions measured at the self-sampling positions BOT1~BOT15, LEF1~LEF15, TL1~TL15, BL1~BL20, TR1~TR20, and BR1~BR15 along direction D1, thereby reducing critical dimension variation.
[0079] Although the embodiments of this case have been disclosed above, they are not intended to limit the scope of this case. Those skilled in the art can make various modifications and alterations without departing from the spirit and scope of this case. Therefore, the scope of protection of this case shall be determined by the appended claims.
[0080] [Symbol Explanation]
[0081] To make the above and other objects, features, advantages and embodiments of this disclosure more apparent and understandable, the accompanying symbols are explained as follows:
[0082] 100: Photolithography process control system
[0083] 110: Photolithography equipment
[0084] 120: Controller
[0085] 122: Processor
[0086] 124: Memory
[0087] 130: Measuring machine
[0088] 10: Wafer
[0089] 11: Exposure Area
[0090] 12, 13: Exposure area
[0091] INT: Deviation range
[0092] CDD1, CDD2, ER: Deviation values
[0093] ED1: First Edge
[0094] ED2: Second Edge
[0095] RBOT: First Edge Region
[0096] RLFT: Second Edge Region
[0097] RTL: First Corner Region
[0098] RBR: Second Corner Area
[0099] RTR: Third Corner Area
[0100] RBL: Fourth Corner Area
[0101] D1: Direction
[0102] P1~P20: Path
[0103] T BOT1 ,T BOT2 ,T BOT3 First trend of change
[0104] T LEF1 ,T LEF2 ,T LEF3 Second trend of change
[0105] BOT1~BOT15, LEF1~LEF15, TL1~TL15, BL1~BL20, TR1~TR20, BR1~BR15: Sampling locations
[0106] R: radius
[0107] BIAS: Bias Average
[0108] C1, C2: Central sampling location
[0109] E1, E2: Sampling locations in the surrounding area
[0110] x: Horizontal direction
[0111] y: vertical direction
[0112] 200: Measurement Method
[0113] S210, S220, S230, S240, S250, S251, S252, S253, S254, S255, S260, S270, S272, S312, S314, S316, S318, S320, S322: Steps.
Claims
1. A metrology method, characterized by, Include: Multiple exposure areas are formed on the wafer based on a photomask; The peripheral critical dimensions of each of the plurality of exposure areas are measured at corresponding peripheral sampling positions within a portion of the plurality of exposure areas, and the central critical dimensions of each of the plurality of exposure areas are measured at corresponding central sampling positions within the plurality of exposure areas within the portion of the plurality of exposure areas. Calculate the deviation between the peripheral critical dimension and the central critical dimension of each of the plurality of exposure areas in the portion; Determine whether the deviation value of each of the plurality of exposure areas in the portion is within the deviation range; If the deviation values of each of the plurality of exposure areas are within the deviation interval, assess the amount of deviation change of one of the plurality of exposure areas in the principal deviation direction; and The parameters of the photomask are adjusted based on the amount of deviation change of the plurality of exposure areas in the main deviation direction.
2. The metrology method of claim 1, wherein, The evaluation steps described therein include: Select a first edge region and a second edge region from one of the plurality of exposure regions; Multiple first critical dimensions are measured along the direction in the first edge region, and multiple second critical dimensions are measured along the direction in the second edge region; A first comparison result is generated based on the first variation trend of the plurality of first critical dimensions along the direction and the second variation trend of the plurality of second critical dimensions along the direction; The principal deviation direction of the subject in the plurality of exposure areas is evaluated based on the first comparison result; and The amount of deviation change along the main deviation direction in the plurality of exposure areas is evaluated based on either the first or the second trend.
3. The metrology method of claim 2, wherein, The first edge region is the region selected by the center point of the subject in the plurality of exposure regions along the first edge of the subject in the plurality of exposure regions in a vertical direction, and the second edge region is the region selected by the center point of the subject in the plurality of exposure regions along the second edge of the subject in the plurality of exposure regions in a horizontal direction.
4. The metrology method of claim 3, wherein, Also includes: If the first comparison result is that the first trend of change is greater than the second trend of change, the main deviation direction of the plurality of exposure areas is determined to be the vertical direction, and the amount of deviation change along the vertical direction is evaluated based on the first trend of change. as well as If the first comparison result is that the first trend of change is less than the second trend of change, the main deviation direction of the plurality of exposure areas is determined to be the horizontal direction, and the amount of deviation change along the horizontal direction is evaluated based on the second trend of change.
5. The metrology method of claim 1, wherein, Also includes: A first corner region, a second corner region, a third corner region, and a fourth corner region are selected from the plurality of exposure regions, wherein the first corner region and the second corner region are located on the first diagonal of the plurality of exposure regions, and the third corner region and the fourth corner region are located on the second diagonal of the plurality of exposure regions. as well as Multiple third critical dimensions, multiple fourth critical dimensions, multiple fifth critical dimensions, and multiple sixth critical dimensions were measured in the first corner region, the second corner region, the third corner region, and the fourth corner region, respectively.
6. The metrology method of claim 5, wherein, Also includes: The amount of change at the first corner of the first diagonal and the amount of change at the second corner of the second diagonal in the plurality of exposure areas are evaluated based on the plurality of third critical dimensions, the plurality of fourth critical dimensions, the plurality of fifth critical dimensions and the plurality of sixth critical dimensions.
7. The metrology method of claim 6, wherein, Also includes: The photomask is adjusted based on the main deviation direction, the deviation change, the first corner change, and the second corner change.
8. The measurement method according to claim 1, characterized in that, Each of the plurality of exposure areas is a pattern composed of multiple oblique straight lines.
9. The measurement method according to claim 1, characterized in that, The range of the deviation interval is less than one-twentieth of the target critical size.
10. A photolithography process control system, characterized in that, Include: Photolithography equipment is used to form multiple exposure areas on a wafer based on a photomask; A measuring instrument measures the peripheral critical dimensions of each of the plurality of exposure areas at corresponding peripheral sampling positions within a portion of the plurality of exposure areas, and measures the central critical dimensions of each of the plurality of exposure areas at corresponding central sampling positions within the plurality of exposure areas; and The processor, connected to the photolithography equipment and the metrology machine, is used to perform the following steps: Calculate the deviation between the peripheral critical dimension and the central critical dimension of each of the plurality of exposure areas in the portion; Determine whether the deviation value of each of the plurality of exposure areas in the portion is within the deviation range; If the deviation values of each of the plurality of exposure areas are within the deviation range, evaluate the amount of deviation change of one of the plurality of exposure areas in the main deviation direction; as well as The parameters of the photomask are adjusted based on the amount of deviation change in the main deviation direction of the exposure areas.