Method of manufacturing photomask

Abstract

In a method for manufacturing a photomask, a target layout having a target pattern to be implemented in the photomask is designed, and a registration correction map can be generated by reflecting overlay error data of a wafer. Subsequently, the registration correction map is reflected in the target layout to generate a correction layout, and an exposure process, a development process, and an etching process are performed on a blank mask to form the photomask. Then, the photomask can be inspected (or measured) based on the correction layout.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a photomask, and more specifically, to a method for manufacturing a photomask for transferring a circuit pattern onto a substrate. Background Technology

[0002] As various bonding schemes are applied at the wafer level, asymmetric warpage occurs, which may result in overlay errors. To resolve this, when adjusting the hardware of the wafer scanner, such as the lens or stage, there is a problem of unwanted deformation because correction in the X direction and correction in the Y direction cannot be performed completely independently. Additionally, in the case of correction using hardware, there is a problem of asymmetric deformation occurring asymmetrically with respect to deformation in the X direction and deformation in the Y direction. To resolve this, the overlay error can be mitigated by performing modeling to reflect the overlay error to generate a registration correction map, and by controlling the deflector of the exposure device based on the registration correction map to adjust the position of the pattern formed on the photomask. However, if the difference between the position of the target pattern of the photomask and the position of the actual pattern implemented in the photomask is greater than the automatic correction range of the inspection device, a large number of defects are detected and the inspection device stops, or measurement values ​​such as CD (critical dimension) and registration error are measured abnormally, making it impossible to inspect and measure the photomask normally. The problem to be solved

[0003] One objective of the present invention is to provide a method for manufacturing a photomask to minimize positional error of the photomask and to normally inspect and measure the photomask. means of solving the problem

[0004] In a method for manufacturing a photomask according to exemplary embodiments for achieving one objective of the present invention, a target layout having a target pattern to be implemented in the photomask is designed, and a registration correction map is generated by reflecting overlay error data of a wafer. Then, a correction layout is generated by reflecting the registration correction map in the target layout, and the photomask is formed by performing an exposure process, a development process, and an etching process on a blank mask. Then, the photomask is inspected based on inspection conditions set based on the correction layout.

[0005] In a method for manufacturing a photomask according to exemplary embodiments for achieving one objective of the present invention, a target layout having a target pattern to be implemented in the photomask is designed, and a circuit pattern is formed on a wafer based on the target layout. Then, an overlay error is measured from the circuit pattern on the wafer to obtain overlay error data, modeling is performed based on the overlay error data, and a registration correction map is generated by reflecting the overlay error data. Then, the registration correction map is reflected in the target layout of the photomask to generate a correction layout, and an exposure process, a development process, and an etching process are performed on a blank mask to form the photomask. Then, the photomask is measured based on measurement conditions set based on the correction layout.

[0006] In a method for manufacturing a photomask according to exemplary embodiments for achieving one objective of the present invention, a target layout having a target pattern to be implemented in the photomask is designed, and a position error correction map is generated by reflecting overlay error data of a wafer. Then, a correction layout is generated by reflecting the position error correction map in the target layout of the photomask, and an exposure process, a development process, and an etching process are performed on a blank mask to form the photomask. Then, a measurement recipe including measurement conditions for measuring the critical dimension (CD) and position error of the patterns formed in the photomask is generated based on the correction layout, and an inspection recipe including inspection conditions for inspecting the photomask is generated based on the correction layout. Then, a measurement control signal reflecting the measurement recipe is applied to a measurement device to measure the photomask based on the measurement conditions, and an inspection control signal reflecting the inspection recipe is applied to an inspection device to inspect the photomask based on the inspection conditions.

[0007] A manufacturing apparatus for a photomask according to exemplary embodiments for achieving one objective of the present invention comprises: an exposure apparatus for performing an exposure process by irradiating an exposure beam onto a substrate; a control unit for applying a control signal to the exposure apparatus to perform an exposure process based on a target layout received from a design system; a correction unit connected to the control unit for correcting a position error of a pattern implemented on the substrate; and a photomask measuring apparatus for measuring the substrate on which the pattern is formed, wherein the control unit has a data correction unit for designing a correction layout by reflecting the position error in the target layout, and the photomask measuring apparatus has a measurement control unit for measuring the substrate based on the correction layout.

[0008] In exemplary embodiments, the photomask manufacturing apparatus further includes a photomask inspection apparatus for inspecting the substrate on which the pattern is formed.

[0009] In exemplary embodiments, the photomask inspection device comprises an inspection control unit for inspecting the substrate based on the correction layout.

[0010] In exemplary embodiments, the exposure device can perform an exposure process by irradiating an exposure beam onto a substrate based on the correction layout.

[0011] In exemplary embodiments, the correction unit includes a wafer measuring device for measuring an overlay error of a wafer and collecting overlay error data, and a registration tool for generating a position error correction map based on the overlay error data received from the wafer measuring device.

[0012] In exemplary embodiments, the exposure device comprises a deflector for performing an exposure process based on the position error correction map.

[0013] In exemplary embodiments, the control unit includes a data receiving unit for receiving the target layout from a design system and receiving a position error correction map from a registration tool, a data correction unit for generating a correction layout based on the target layout and the position error correction map received from the data receiving unit, and an output unit for transmitting a control signal reflecting at least one of the correction layout and the position error correction map to the exposure device.

[0014] In exemplary embodiments, the registration tool can generate the position error correction map by modeling the overlay error data.

[0015] In exemplary embodiments, the data correction unit can design a verification layout by inversely applying the position error correction map to the correction layout.

[0016] In exemplary embodiments, the data correction unit can verify the correction layout by comparing the verification layout with the target layout. Effects of the invention

[0017] In a method for manufacturing a photomask according to exemplary embodiments, a target layout having a target pattern to be implemented in the photomask is designed, and a registration correction map can be generated by reflecting overlay error data of a wafer. Then, the registration correction map can be reflected in the target layout of the photomask to generate a correction layout, and the photomask can be formed by performing an exposure process, a development process, and an etching process on a blank mask. After that, the photomask can be inspected based on the correction layout, and the photomask can be measured based on the correction layout.

[0018] Performing an exposure process on the blank mask may include performing the exposure process on the blank mask by reflecting at least one of the position error correction map and the correction layout.

[0019] Accordingly, the error between the position of the actual pattern implemented in the photomask and the position of the originally designed target pattern is corrected, thereby enabling the production of a photomask in which the actual pattern is implemented closer to the layout of the target pattern. Furthermore, problems that may occur when correcting by adjusting hardware such as a lens or a stage can be prevented. For example, since correction in the X direction and correction in the Y direction cannot be performed completely independently, problems such as unwanted deformation and asymmetric deformation can be prevented.

[0020] In addition, measuring the photomask based on the correction layout may include generating a measurement recipe that includes measurement conditions for measuring the critical dimension (CD) and registration error of patterns formed on the photomask based on the correction layout, and applying a measurement control signal reflecting the measurement recipe to a measurement device. Also, inspecting the photomask based on the correction layout may include generating an inspection recipe that includes inspection conditions for inspecting the photomask based on the correction layout, and applying an inspection control signal reflecting the inspection recipe to an inspection device.

[0021] Accordingly, inspection and measurement of the photomask can be performed normally even when the difference between the position of the target pattern of the photomask and the position of the actual pattern implemented in the photomask is greater than the automatic correction range of the inspection device.

[0022] However, the effects of the present invention are not limited to the effects mentioned above and may be extended in various ways without departing from the spirit and scope of the present invention. Brief explanation of the drawing

[0023] FIG. 1 is a block diagram showing a photomask manufacturing apparatus according to exemplary embodiments. Figure 2 is a schematic diagram showing the exposure apparatus of Figure 1. Figure 3 is a schematic diagram showing the measuring device and inspection device of Figure 1. FIG. 4 is a flowchart illustrating a method for manufacturing a photomask according to exemplary embodiments. FIG. 5 is a plan view showing the target layout of a photomask according to exemplary embodiments. FIG. 6 is a plan view illustrating a photomask according to exemplary embodiments and areas where light is reflected from the photomask and projected onto a wafer in an exposure process using the same. Figure 7 is a diagram showing points sampled within a single shot to measure the actual overlay error of the actual pattern implemented on the wafer. FIG. 8A is a graph showing correction values ​​corresponding to each of the measured coordinates to correct the position error by reflecting the measured overlay error. FIG. 8B is a graph showing a position error correction map according to exemplary embodiments generated by performing modeling on the correction values ​​of FIG. 8A. Figure 9A is a graph showing the X-direction component of the position error correction map of Figure 8B. Figure 9B is a graph showing the Y-direction component of the position error correction map of Figure 8B. FIG. 10 is a plan view showing a correction layout according to exemplary embodiments in which the position error correction map of FIG. 8B is reflected in the target layout of FIG. 5 to correct it. FIG. 11A is a graph measuring the position error of a pattern actually implemented on a photomask based on the target layout of FIG. 5. FIG. 11B is a graph measuring the position error of a pattern actually implemented on a photomask based on the correction layout of FIG. 10. Figure 12A is a graph showing the correction values ​​input to correct position errors. FIG. 12B is a graph showing the distance traveled by the stage of the measuring device when measuring the critical dimension of a pattern actually implemented on a photomask based on the target layout of FIG. 5. FIG. 12C is a graph showing the distance traveled by the stage of the measuring device when measuring the critical dimension of a pattern actually implemented on a photomask based on the correction layout of FIG. 10. FIG. 13 is a flowchart illustrating a method for manufacturing a photomask according to exemplary embodiments. FIG. 14 is a block diagram showing a photomask manufacturing apparatus according to exemplary embodiments. FIG. 15 is a cross-sectional view showing the exposure process being performed on a blank mask using the exposure apparatus of FIG. 14. Specific details for implementing the invention

[0024] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the attached drawings.

[0025] FIG. 1 is a block diagram showing a photomask manufacturing apparatus according to exemplary embodiments. FIG. 2 is a schematic diagram showing an exposure apparatus of FIG. 1. FIG. 3 is a schematic diagram showing a measuring apparatus and an inspection apparatus of FIG. 1.

[0026] Referring to FIGS. 1 to 3, the photomask manufacturing device may include an exposure device (100) and a control unit (200) for controlling the exposure device (100). The exposure device (100) may expose a substrate (10) with an exposure beam by means of a control signal according to design data provided to the control unit (200). Additionally, the photomask manufacturing device may further include a registration tool (300) connected to the control unit (200) for processing data regarding positional errors, and a wafer measuring device (400) connected to the registration tool (300) for measuring an overlay error of an actual implemented pattern on a wafer. Additionally, the photomask manufacturing device may further include a photomask measuring device (500) for measuring an actual implemented pattern on the photomask and a photomask inspection device (600) for inspecting an actual implemented pattern on the photomask, each connected to a control unit (200).

[0027] In exemplary embodiments, the exposure device (100) may generate a pattern on a substrate (10) using at least one exposure beam (B). The exposure device (100) may be a device for writing a pattern on a substrate coated with a photosensitive material. The exposure device (100) may be used to manufacture a photomask or reticle used in a wafer lithography process. For example, the exposure beam (B) may include a laser beam, an electron beam, etc. The exposure device (100) may include a scanning device that directs the exposure beam (B) toward the substrate (10) on the exposure stage and scans it.

[0028] The above exposure device may include a deflector used for exposure operations. The deflector can deflect the exposure beam onto the substrate to form patterns. Additionally, the exposure stage can support and move the substrate. The exposure stage can be moved in the X direction or the Y direction by means of a driver.

[0029] A substrate (10) may include a sequentially formed mask substrate (12), a light-blocking film (14), and a photosensitive film (16). The mask substrate (12) may be a transparent substrate, a reflective substrate, or an absorbing substrate. For example, the mask substrate (12) may include glass or quartz. The light-blocking film (14) may include a metal film such as chromium. The substrate (10) may be used as a photomask or reticle used in a wafer lithography process. An exposure device (100) may form a photosensitive pattern (P) by exposing the photosensitive film (16) on the substrate (10) with exposure beams (B) according to the design data. For example, the substrate may be a blank mask in which no pattern is formed.

[0030] When the substrate (10) is exposed to the exposure beam according to the above design data, the photosensitive pattern (P) may have a positional error, i.e., a registration error, with respect to the above design data. For example, the exposure device may be a device for ensuring that the photosensitive pattern (P) has the same shape at the same location as the mask pattern on the above design data. However, due to the positional error of the pattern occurring during the photomask manufacturing process, the pattern of the photomask may have a registration error locally or entirely. For example, the photomask pattern on the substrate (10) may have a positive (+) or negative (-) registration error in the X-axis or Y-axis direction.

[0031] In exemplary embodiments, the control unit (200) may be a device for controlling the exposure device (100) to expose the exposure beam according to the output control signal by outputting a control signal. The control unit (200) may include a data receiving unit (210), a data correction unit (220), and an output unit (230). Additionally, the control unit (200) is connected to a registration tool (300) connected to a wafer measuring device (400) and may receive data regarding the position error from the registration tool (300). For example, the control unit (200) may output a control signal to control the exposure device (100) to expose the exposure beam on the substrate (10) by reflecting the data regarding the position error.

[0032] The data receiving unit (210) can receive design pattern data, i.e., a target layout (TL), from a pattern design system. For example, the design pattern data may be data for a target layout (TL) having a target pattern to be implemented in a photomask. Additionally, the design pattern data may be provided as coordinate values ​​of the outline of the target pattern. The design pattern data may be provided by a combination of polygons (triangles, squares). The design pattern data may consist of multiple sub-patterns of polygonal shapes forming a single pattern. The design pattern data may include information regarding the size and position of the multiple sub-patterns.

[0033] Additionally, the data receiving unit (210) can receive data regarding the position error of the pattern actually implemented on the substrate (10). For example, the position error data can be received from a registration tool (300).

[0034] For example, a wafer measuring device (400) can measure a circuit pattern formed on a wafer by utilizing a photomask in which the target pattern of the target layout is implemented. The wafer measuring device (400) can obtain overlay error data (EDA) from the circuit pattern of the wafer. The overlay error data may be data regarding the error between the location of the circuit pattern formed on the actual wafer and the location of the pattern to be implemented. In this case, the overlay error data may be data regarding a sampled portion of the circuit pattern formed on the actual wafer.

[0035] Additionally, the wafer measuring device (400) can extract components that are difficult to correct with the wafer exposure equipment (or components that cannot be corrected with the wafer exposure equipment) from the overlay error data (EDA) and transmit them to the registration tool (300). For example, the overlay error data (EDA) may include first error data that is easily corrected by adjusting hardware such as the lens or stage of the scanner of the wafer exposure equipment, and second error data that is difficult to correct by adjusting said hardware. The wafer measuring device can extract only said second error data and transmit it to the registration tool (300). For example, said second error data may be error data related to asymmetric mag, where deformation of the pattern in the X direction and deformation of the pattern in the Y direction occur asymmetrically when adjusting the hardware to correct positional error. In addition, the second error data may be data related to a high-order term of degree 3 or higher among a plurality of terms included in a polynomial obtained by performing polynomial regression on overlay error data (EDA).

[0036] Additionally, the registration tool (300) is connected to the wafer measuring device (400), receives overlay error data (EDA) from the wafer measuring device (400), and can generate a registration correction map (RM) using the overlay error data (EDA). For example, the registration correction map is data that represents correction values ​​required to minimize (or eliminate) the position error for each corresponding coordinate on a coordinate plane. For example, the correction values ​​may be data that represents the required horizontal movement distance and direction for each corresponding coordinate in the form of arrows on an XY plane.

[0037] The registration tool (300) can analyze overlay error data (EDA) and calculate a correction value to minimize positional error, that is, the error between the position of the circuit pattern formed on the actual wafer and the position of the pattern to be implemented. In addition, the registration tool (300) can perform modeling based on the overlay error data (EDA) to calculate correction values ​​for unmeasured areas. For example, the modeling can be performed through polynomial interpolation or thin plate spline interpolation.

[0038] The data correction unit (220) can correct the design data, i.e., the target layout (TL), by changing the position data of the pattern based on the position error correction map (RM).

[0039] For example, a correction layout (CL) can be generated by reflecting a position error correction map (RM) to a target layout (TL). The correction layout may be a DBRC (design based registration correction) layout in which overlay error data (EDA) of an actual circuit pattern implemented on a wafer is reflected in the target layout (TL).

[0040] Specifically, a grid is defined to divide a target layout (TL) having a target pattern to be implemented in the photomask into a desired size, and a position error correction map (RM) is reflected on the grid to reposition the positions of sub-patterns included in the target pattern to generate a correction layout (CL). The correction layout may be design data in which the X and Y coordinates included in the target layout (TL) are translated in the XY plane to minimize (or eliminate) the position error.

[0041] Additionally, the data correction unit (220) can perform interpolation on coordinates included in the target layout (TL) that are not included in the position error correction map (RM), and calculate correction values ​​for said coordinates that are not included in the position error correction map (RM). For example, bilinear interpolation may be used for the interpolation.

[0042] Additionally, the data correction unit (220) can verify the correction layout (CL). For example, the data correction unit (220) can generate a verification layout by inversely reflecting the position error correction map (RM) into the correction layout (CL). The signs of the correction values ​​included in the position error correction map (RM) can be reversed, and the coordinates of the correction layout (CL) can be moved based on the changed correction values. Then, by comparing the verification layout with the target layout (TL), it can be confirmed whether the correction layout (CL) was generated correctly. Specifically, it can be confirmed whether the correction layout (CL) was generated correctly by checking whether there are patterns that have moved to an incorrect position, patterns that have deformed shapes, or patterns that have disappeared in the verification layout.

[0043] The output unit (230) can output corrected design data, i.e., a corrected layout (CL), and can output a control signal for controlling the exposure device (100) according to the corrected layout (CL). The exposure device (100) can expose the exposure beam onto the substrate (10) according to the control signal.

[0044] In exemplary embodiments, the photomask measuring device (500) may be a device for measuring an actual pattern (P') implemented on a photomask, and may have a measuring device control unit (510) connected to a control unit (200). For example, the photomask measuring device may be a device for measuring the critical dimension (CD) and registration error of the actual pattern. For example, the critical dimension may be the minimum size required for the pattern. Additionally, the registration error may be the difference between the position of the pattern in the design data and the position of the actually implemented pattern.

[0045] The measuring device control unit (510) can set conditions for measuring the actual pattern (P') based on the correction layout (CL) transmitted by the control unit (200).

[0046] For example, the measuring device control unit (510) can generate a measurement recipe for measuring an actual pattern (P') based on a correction layout (CL) and apply a measurement control signal (CMD) to a photomask measuring device (500) based on the measurement recipe. For example, the measuring device control unit can generate a measurement recipe that includes measurement conditions for measuring a photomask based on the correction layout (CL). For example, the measurement recipe may include critical dimension measurement conditions for measuring a critical dimension based on the correction layout (CL) and position error measurement conditions for measuring a position error based on the correction layout (CL). For example, the measurement conditions included in the measurement recipe may include a measurement position, a measurement range, a measurement magnification, the intensity of the measurement light, a measurement direction, a measurement mode (setting measurement methods such as reflection, transmission, etc.).

[0047] For example, the measuring device control unit (510) can generate a reference image for measuring at least one of a critical dimension and a position error based on a correction layout (CL).

[0048] For example, the measurement device control unit may output a measurement control signal (CMD) reflecting the measurement recipe to the measurement device (500) in order to perform a measurement according to the measurement recipe.

[0049] In exemplary embodiments, the photomask inspection device (600) is equipped with an inspection device control unit (610) connected to a control unit (200) and may be a device for inspecting an actual pattern (P') implemented on a photomask. The photomask inspection device may be a device for selecting defective photomasks by inspecting whether the actual pattern is contaminated, whether critical dimension conditions are satisfied, whether positional error conditions are satisfied, etc.

[0050] The inspection device control unit (610) can generate an inspection recipe for measuring an actual pattern (P') based on a correction layout (CL) transmitted by the control unit (200), and can apply an inspection control signal (CID) to a photomask inspection device (600) based on the inspection recipe. For example, the inspection device control unit can generate an inspection recipe that includes inspection conditions for inspecting a photomask based on the correction layout (CL). Then, the inspection device control unit can output an inspection control signal (CID) reflecting the inspection recipe to the inspection device (600) to perform an inspection according to the inspection recipe.

[0051] For example, the inspection conditions included in the above inspection recipe may include an inspection location, inspection range, inspection magnification, inspection light intensity, inspection direction, inspection mode, etc.

[0052] The photomask measuring device (500) and the photomask inspection device (600) can perform automatic correction for a position error (registration error) within a certain range. For example, if a first pattern having a first position error is implemented on a photomask, and the magnitude of the first position error is within the automatic correction range, measurement and inspection can be performed normally. For example, the automatic correction range may be within '0 nm' to '370 nm'. However, it will be understood that this is exemplary and the present invention is not limited thereto. Accordingly, the automatic correction range may be changed depending on the type of measuring device or the type of inspection device.

[0053] Additionally, although not illustrated in the drawings, the manufacturing apparatus of the photomask according to exemplary embodiments may further include a heating device for performing a baking process to heat a photoresist layer applied to the photomask, a developing device for performing a developing process to remove a portion of the photoresist layer that has received light (or has not received light) after the exposure process is performed, an etching device for performing an etching process to remove a portion of the light-shielding film exposed by the photoresist pattern formed by the developing process, and a cleaning device for performing a strip process to remove a residue including the photoresist pattern remaining after the etching process.

[0054] As described above, a photomask manufacturing device according to exemplary embodiments may include a registration tool (300) for generating a position error correction map (RM) based on overlay error data (OED), a control unit (200) for generating a correction layout (CL) by correcting a target layout (TL) based on the position error correction map (RM), an exposure device (100) for performing an exposure process based on the correction layout (CL), a photomask measuring device (500) for measuring the photomask based on measurement conditions set based on the correction layout (CL), and a photomask inspection device (600) for inspecting the photomask based on inspection conditions set based on the correction layout (CL).

[0055] Therefore, the error between the position of the actual pattern implemented in the photomask and the position of the originally designed target pattern is corrected, thereby enabling the production of a photomask in which the actual pattern is implemented closer to the layout of the target pattern. Furthermore, problems that may occur when correcting by adjusting hardware such as a lens or a stage can be prevented. For example, since correction in the X direction and correction in the Y direction cannot be performed completely independently, problems such as unwanted deformation and asymmetric deformation can be prevented.

[0056] In addition, inspection and measurement of the photomask can be performed normally even when the difference between the position of the target pattern of the photomask and the position of the actual pattern implemented in the photomask is greater than the automatic correction range of the inspection device.

[0057] Below, a method for manufacturing a photomask using the photomask manufacturing apparatus of FIG. 1 will be described.

[0058] FIG. 4 is a flowchart illustrating a method for manufacturing a photomask according to exemplary embodiments. FIG. 5 is a plan view illustrating a target layout of a photomask according to exemplary embodiments. FIG. 6 is a plan view illustrating a photomask according to exemplary embodiments and areas where light is reflected from the photomask and projected onto a wafer in an exposure process using the same. FIG. 7 is a diagram illustrating points sampled within a single shot to measure the actual overlay error of an actual pattern implemented on a wafer. FIG. 8A is a graph showing correction values ​​corresponding to each measurement coordinate to correct positional error by reflecting the measured overlay error. FIG. 8B is a graph showing a positional error correction map according to exemplary embodiments generated by performing modeling on the correction values ​​of FIG. 8A. FIG. 9A is a graph showing the X-direction component of the positional error correction map of FIG. 8B. FIG. 9B is a graph showing the Y-direction component of the positional error correction map of FIG. 8B. FIG. 10 is a plan view showing a correction layout according to exemplary embodiments in which the position error correction map of FIG. 8B is reflected in the target layout of FIG. 5 to correct it.

[0059] Since the photomask manufacturing apparatus used in the method of manufacturing a photomask described with reference to FIGS. 4 to 10 is substantially the same as the photomask manufacturing apparatus described in FIGS. 1 to 3, identical components are indicated by identical reference numerals, and a repeated description of identical components is omitted.

[0060] Referring to FIGS. 4 and 5, in the first step (S10), a target layout (TL) having a target pattern can be designed. For example, the target layout may be design data representing a target pattern to be implemented on a photomask. As shown in FIG. 5, when the target layout is represented on an XY plane, it may have a pre-set target pattern within a certain area.

[0061] Referring to FIGS. 1, FIGS. 4, FIGS. 6, and FIGS. 7, in the second step (S20), a photomask (M) fabricated based on a target layout (TL) is projected to form a circuit pattern on a wafer (WF), and an overlay error of the circuit pattern is measured using a wafer measuring device (400) to obtain overlay error data (EDA).

[0062] For example, an exposure process is performed on a photomask (M) based on a target layout (TL), and then a development process, an etching process, and a cleaning process are performed to produce a photomask (M) having a target pattern.

[0063] Then, light is irradiated onto one side of the photomask (M), and the light reflected from the photomask (M) is guided to the wafer (WF) by an optical system included in the wafer exposure device and can be incident on one side of the wafer (WF).

[0064] At this time, the area of ​​light incident on the wafer (WF) can be reduced by a certain ratio, i.e., a reduction ratio, compared to the area of ​​light incident on the photomask (M). That is, the optical system can have a certain reduction ratio. For example, the optical system can have a reduction ratio of 4:1 for each x and y direction. For example, the area of ​​the wafer (WF) where the layout of the pattern included in the photomask (M) is transferred by a single first exposure process using the photomask (M), i.e., one shot, can be defined as a field (F).

[0065] Then, by performing a development process, an etching process, and a cleaning process on the wafer (WF), a circuit pattern corresponding to the target pattern of the target layout (TL) can be formed.

[0066] Subsequently, the circuit pattern of the wafer (WF) can be measured to obtain data regarding the overlay error of the wafer (WF), i.e., overlay error data (EDA). Specifically, the wafer (WF) can be divided into a virtual region divided into multiple shots (SH). Each shot may correspond to a field (F) on which the layout of the pattern included in the photomask (M) is transferred. Referring to the 'M2' section of FIG. 7, multiple points (PT) included within the field (F) can be sampled to measure the overlay error occurring at each of the multiple points (PT). For example, the number of the multiple points may be 1500. The overlay error data (EDA) may include coordinate values ​​on the XY plane of the multiple points (PT), numerical values ​​of the overlay error corresponding to each of the multiple points (PT), etc.

[0067] Referring to FIGS. 1, FIGS. 4, FIGS. 8A, FIGS. 8B, FIGS. 9A, and FIGS. 9B, in the third step (S30), a registration correction map (RM) can be generated based on overlay error data (EDA) received from a wafer measuring device (400) by utilizing a registration tool (300).

[0068] Referring again to FIG. 8A, first correction data (CD1) can be calculated by analyzing overlay error data (EDA) to minimize (or eliminate) the overlay error in the target pattern of the target layout (TL). For example, the correction data may include coordinate values ​​of the target layout (TL) corresponding to multiple points (PT) of the overlay error data (EDA), and correction values ​​required for each of the coordinate values ​​of the target layout (TL). For example, it can be seen that a shift is required in the -X direction and +Y direction from the first coordinate (T1), and since the required shift distance is proportional to the size of the arrow, a relatively large amount of shift is required. Additionally, it can be seen that a shift is required in the -X direction and -Y direction from the second coordinate (T2), and a relatively large amount of shift is required.

[0069] Referring again to FIG. 8B, modeling can be performed based on the calculated first correction data (CD1) to calculate the second correction data (CD2, not shown) required at points that do not correspond to multiple points (PT) of the overlay error data (EDA) (parts not measured in the aforementioned overlay error measurement step), and the first correction data (CD1) and the second correction data (CD2) can be represented on XY coordinates to generate a position error correction map (RM). For example, the modeling can be performed through polynomial interpolation or thin plate spline interpolation.

[0070] For example, referring to the 'M3' section of FIG. 8B, the position error correction map (RM) may include correction data of relatively many coordinates compared to the first correction data (CD1) of FIG. 8A.

[0071] Referring again to FIG. 9A, the amount of correction required in the X direction at each coordinate of the position error correction map (RM) can be seen. For example, it can be seen that at the first point (P1a), a movement of '1 / 3 [AU]' in the X direction is required, at the second point (P2a), a movement of '~0 [AU]' in the X direction is required, and at the third point (P3a), a movement of '-1 / 3 [AU]' in the X direction is required. For example, the amount of correction required in the X direction can be normalized to a range of '-1' to '1+' and displayed in a different color. As used herein, '[AU]' represents an arbitrary unit, which may be a dimensionless value derived from normalization or relative measurement. Therefore, it does not correspond to a specific physical unit and can be used for comparative analysis.

[0072] Referring again to FIG. 9B, the amount of correction required in the Y direction at each coordinate of the position error correction map (RM) can be seen. For example, it can be seen that a movement of '-300 [AU]' in the Y direction is required at the first point (P1b), a movement of '~0 [AU]' in the Y direction is required at the second point (P2b), and a movement of '+300 [AU]' in the Y direction is required at the third point (P3b). For example, the amount of correction required in the Y direction can be normalized to a range of '-1' to '1+' and displayed in a different color. As used herein, '[AU]' represents an arbitrary unit, which may be a dimensionless value derived from normalization or relative measurement. Therefore, it does not correspond to a specific physical unit and can be used for comparative analysis.

[0073] Referring to FIGS. 1, FIGS. 4, and FIGS. 10, in the fourth step (S40), the control unit (200) can generate a correction layout (CL) by reflecting a position error correction map (RM) transmitted from a registration tool (300) onto a target layout (TL) received from a pattern design system. For example, the correction layout may be a DBRC (design based registration correction) layout in which overlay error data (EDA) is reflected onto the target layout (TL).

[0074] For example, the data receiving unit (210) receives a position error correction map (RM) and a target layout (TL), and the data correction unit (220) can generate a correction layout (CL) by reflecting the position error correction map (RM) in the target layout (TL).

[0075] Referring to section 'M4' in Fig. 10, the correction layout (CL) and the target layout (TL) can be identified. The correction layout (CL) can be generated by rearranging the coordinates included in the target layout (TL) according to the correction values ​​required in the position error correction map (RM). However, it should be noted that the target layout (TL) is shown for comparison with the correction layout (CL), and that the target layout (TL) and the correction layout (CL) are not included in a single design data.

[0076] Referring to FIGS. 1 and FIGS. 4, in the fifth step (S50), the output unit (230) outputs the correction layout (CL) generated by the data correction unit (220) to the photomask measuring device (500) and the photomask inspection equipment (600), the photomask measuring device (500) sets the measurement conditions of the photomask based on the correction layout (CL) (S52), and the photomask inspection equipment (600) sets the measurement conditions of the photomask based on the correction layout (CL) (S54).

[0077] For example, the measurement device control unit (510) of the photomask measurement device (500) can generate a measurement recipe that includes measurement conditions for measuring the pattern of the photomask based on a correction layout (CL). For example, the measurement recipe may include critical dimension measurement conditions for measuring a critical dimension based on the correction layout (CL) and position error measurement conditions for measuring a position error based on the correction layout (CL). For example, the measurement conditions included in the measurement recipe may include a measurement position, a measurement range, a measurement magnification, the intensity of the measurement light, a measurement direction, a measurement mode (e.g., setting a measurement method such as reflection, transmission, etc.).

[0078] For example, the measuring device control unit (510) can generate a reference image for measuring at least one of a critical dimension and a position error based on a correction layout (CL). For example, a portion extracted (or cut) from the correction layout (CL), such as the 'M4' portion of FIG. 10, can be generated as a reference image.

[0079] Additionally, the inspection device control unit (610) of the photomask inspection device (600) can generate an inspection recipe that includes inspection conditions for inspecting the pattern of the photomask based on the correction layout (CL). For example, the inspection conditions included in the inspection recipe may include an inspection position, an inspection range, an inspection magnification, an intensity of inspection light, an inspection direction, an inspection mode, etc.

[0080] Referring to FIGS. 1, 2 and 4, in step 6 (S60), the output unit (230) outputs the correction layout (CL) generated by the data correction unit (220) to the exposure device (100), and the exposure device (100) can perform an exposure process on the substrate (10), which is a blank mask, by reflecting the correction layout (CL) (S62). Accordingly, the exposure process can be performed at positions changed from the original positions of the target pattern. After that, a photoresist pattern (P) can be created by removing a portion of the photosensitive film (16) of the substrate (10) through a development process, and a photomask (10) having a pattern (P') within the photoresist pattern (14) can be created by removing a portion of the light-shielding film (14) of the substrate (10) exposed by the photoresist pattern (P) through an etching process (S64).

[0081] For example, an exposure process can be performed using an exposure device (100) so that a portion corresponding to a correction layout (CL) on a photosensitive film (16) of a substrate (10) receives an exposure beam (B) (or so that a portion corresponding to a correction layout (CL) does not receive an exposure beam (B).

[0082] Referring to FIGS. 1, 3 and 4, in step 7 (S70), the photomask measuring device (500) can measure the pattern (P') of the photomask (10) based on the correction layout (CL) (S72). For example, the measuring device control unit (510) can apply a measurement control signal (CMD) reflecting a previously generated measurement recipe to the measuring device (500) to measure the critical dimension (CD) and registration error of the photomask (10) based on the correction layout (CL).

[0083] After that, the photomask inspection device (600) can inspect the photomask (10) based on the correction layout (CL) (S74). For example, the inspection device control unit (610) can inspect the photomask (10) based on the correction layout (CL) by applying an inspection control signal (CID) reflecting a previously generated inspection recipe to the inspection device (600).

[0084] For example, the photomask inspection device described above can identify defective photomasks by inspecting whether contaminants are present in the photomask, whether the pattern implemented in the photomask satisfies critical dimension conditions, and whether the pattern implemented in the photomask satisfies positional error conditions. Specifically, the inspection of the photomask may include a first inspection in which an overall image of the shot is acquired and compared with a reference image to verify whether the size of the pattern and the positional error of the pattern satisfy preset criteria, and a second inspection in which the patterns of each of the multiple die regions provided in the center of the shot are identical to each other. In the case of the first inspection, if the size of the pattern and the positional error of the pattern do not satisfy preset criteria, the corresponding mask may be determined to be defective. Additionally, in the case of the second inspection, if the patterns of each of the multiple die regions are not identical to each other, the mask may be determined to be defective.

[0085] For example, the inspection (or measurement) of a photomask can be performed using light of various wavelengths. For instance, light of various wavelengths such as 193 nm, 257 nm, 365 nm, and 13.5 nm may be used for the inspection or measurement of a photomask. Additionally, argon fluoride (ArF) may be used as a light source. However, it will be understood that this is merely illustrative and the present invention is not limited thereto. Accordingly, the wavelength of light, the light source, etc., used for the inspection and measurement of the photomask may be changed.

[0086] As described above, in a method for manufacturing a photomask according to exemplary embodiments, a target layout (TL) having a target pattern to be implemented in the photomask is designed, and a position error correction map (RM) can be generated by reflecting the overlay error data (OED) of the wafer. Then, a correction layout (CL) is generated by reflecting the position error correction map (RM) in the target layout (TL), and the photomask can be formed by performing an exposure process, a development process, and an etching process on a blank mask (10). After that, the photomask can be inspected based on the correction layout (CL), and the photomask can be measured based on the correction layout (CL).

[0087] Performing an exposure process on the blank mask (10) may include performing an exposure process by reflecting a correction layout (CL).

[0088] Accordingly, the error between the position of the actual pattern implemented in the photomask and the position of the originally designed target pattern is corrected, thereby enabling the production of a photomask in which the actual pattern is implemented closer to the layout of the target pattern. Furthermore, problems that may occur when correcting by adjusting hardware such as a lens or a stage can be prevented. For example, since correction in the X direction and correction in the Y direction cannot be performed completely independently, problems such as unwanted deformation and asymmetric deformation can be prevented.

[0089] Additionally, measuring the photomask based on the correction layout (CL) may include setting critical dimension measurement conditions for measuring the critical dimension (CD) of the patterns formed on the photomask based on the correction layout (CL), and setting position error measurement conditions for measuring the position error of the patterns formed on the photomask based on the correction layout (CL). Furthermore, inspecting the photomask based on the correction layout (CL) may include setting conditions for inspecting the photomask based on the correction layout (CL).

[0090] Accordingly, inspection and measurement of the photomask can be performed normally even when the difference between the position of the target pattern of the photomask and the position of the actual pattern implemented in the photomask is greater than the automatic correction range of the inspection device.

[0091] In the following, it is explained that critical dimension measurement and position error measurement can be performed normally by utilizing the method for manufacturing a photomask described with reference to FIGS. 4 to 10.

[0092] FIG. 11A is a graph showing the positional error of a pattern actually implemented on a photomask based on the target layout of FIG. 5. FIG. 11B is a graph showing the positional error of a pattern actually implemented on a photomask based on the correction layout of FIG. 10. FIG. 12A is a graph showing the correction values ​​input to correct the positional errors. FIG. 12B is a graph showing the distance the stage of the measuring device moved when measuring the critical dimension of a pattern actually implemented on a photomask based on the target layout of FIG. 5. FIG. 12C is a graph showing the distance the stage of the measuring device moved when measuring the critical dimension of a pattern actually implemented on a photomask based on the correction layout of FIG. 10.

[0093] Referring to FIG. 11A, when measuring the repositioning error of a pattern actually implemented on a photomask based on the target layout (TL) of FIG. 5, it can be seen that the repositioning error is measured abnormally. For example, each of the first arrows (P1c, P2c, P3c) may represent the repositioning error that occurred at each of the measurement coordinates. It can be seen that the magnitude of the first arrows diverges beyond the observation area. For example, the magnitude of the first arrows may exceed the automatic correction range of the photomask inspection device (600) (or photomask measurement device (500)). In contrast, referring to FIG. 11B, when measuring the repositioning error of a pattern actually implemented on a photomask based on the correction layout (CL) of FIG. 10, it can be seen that the repositioning error is measured normally. For example, each of the second arrows (P1d, P2d, P3d) may represent the repositioning error that occurred at each of the measurement coordinates. It can be confirmed that the size of the second arrows has a normal size within the observation area. For example, the size of the second arrows may be within the automatic correction range of the photomask inspection device (600) (or photomask measuring device (500)).

[0094] The magnitude of the repositioning error described in FIGS. 11A and 11B can be normalized to a range of '-1' to '1+' and displayed in a different color. As used herein, '[AU]' represents an arbitrary unit, which may be a dimensionless value derived from normalization or relative measurement. Therefore, it does not correspond to a specific physical unit and may be used for comparative analysis.

[0095] Referring to FIGS. 12A and FIGS. 12B, it can be seen that when measuring the critical dimension (CD) of a pattern actually implemented on a photomask based on the target layout (TL) of FIG. 5, the critical dimension is measured abnormally.

[0096] Specifically, referring again to FIG. 12A, the X input value may be an input value for the distance traveled (or correction distance) in the X direction required to correct the position error. Additionally, the Y input value may be an input value for the distance traveled (or correction distance) in the Y direction required to correct the position error. Referring again to FIG. 12B, the X travel distance may be the distance that the stage (not shown) of the critical dimension measuring device travels in the X direction to measure the critical dimension (CD). Additionally, the Y travel distance may be the distance that the stage (not shown) of the critical dimension measuring device travels in the Y direction to measure the critical dimension.

[0097] When comparing the graphs of the Y input value in Fig. 12A and the Y travel distance in Fig. 12B, it can be seen that while the travel distance in the Y direction required to correct the position error has a linear shape, the actual distance traveled in the Y direction by the stage (not shown) of the critical dimension measuring device is interrupted in the middle of the straight line. This difference may occur because, when measuring the critical dimension (CD) of the pattern actually implemented on the photomask based on the target layout (TL), the critical dimension measuring device measures the critical dimension at an incorrect position due to a relatively large position error. Therefore, it can be seen that the critical dimension is measured abnormally.

[0098] Referring to FIG. 12C, it can be seen that when measuring the critical dimension (CD) of a pattern actually implemented on a photomask based on the correction layout (CL) of FIG. 10, the critical dimension is measured normally. The X travel distance may be the distance that the stage (not shown) of the critical dimension measuring device moves in the X direction to measure the critical dimension (CD). Additionally, the Y travel distance may be the distance that the stage (not shown) of the critical dimension measuring device moves in the Y direction to measure the critical dimension. For example, the X travel distance may have a size of '30 nm' or less. Additionally, the Y travel distance may have a size of '60 nm' or less.

[0099] Accordingly, it can be seen that when measuring the critical dimension (CD) of a pattern actually implemented on a photomask based on the correction layout (CL) of FIG. 10, the X displacement and Y displacement are relatively small compared to when measuring the critical dimension (CD) of a pattern actually implemented on a photomask based on the target layout (TL) as described in FIG. 12B. The X displacement and Y displacement may be within a normal range that occurs when the critical dimension (CD) measuring device measures the critical dimension at the correct position.

[0100] FIG. 13 is a flowchart illustrating a method for manufacturing a photomask according to exemplary embodiments. FIG. 14 is a block diagram illustrating a photomask manufacturing apparatus according to exemplary embodiments. FIG. 15 is a cross-sectional view illustrating the performance of an exposure process on a blank mask using the exposure apparatus of FIG. 14.

[0101] Since the above method includes steps that are substantially identical or similar to the method described with reference to FIGS. 4 to 10, redundant descriptions are omitted, and only the differences are described.

[0102] Referring to FIGS. 14 to 16, steps 1 to 4 (S10 to S40) can be performed to generate an error correction map (RM) and a correction layout (CL). Then, step 5 (S100) can be performed to generate a measurement recipe including measurement conditions of a photomask based on the correction layout (CL), and an inspection recipe including inspection conditions based on the correction layout (CL).

[0103] After that, in the eighth step (S61), an exposure process (S63) is performed on the blank mask (10) by reflecting the target layout (TL) and the position error correction map (CL), and a photomask (S64) can be produced by performing a development process and an etching process on the blank mask (10).

[0104] For example, the control unit (200) can apply a control signal to the exposure device (100) by reflecting the target layout (TL) received from the design system and the position error correction map (RM) received from the registration tool (300).

[0105] At this time, the exposure device (100) can perform an exposure process by reflecting a position error correction map (RM). Specifically, referring again to FIG. 16, the exposure device (100) may include an irradiation device (110) that irradiates an exposure beam (B) and a deflector (120) having first to third deflector structures (122, 124, 126) for controlling the direction of the exposure beam (B). During the exposure process, the exposure device (100) that irradiates an exposure beam (B) onto a photosensitive film (16), which is a photoresist film of a photomask (10), can correct the irradiation direction of the exposure beam, for example, through the deflector (120), based on the position error correction map. That is, by adjusting the bias value applied by the exposure device to the deflector according to the value of the position error correction map, the position of the actual pattern implemented in the photomask can be corrected. In exemplary embodiments, the exposure beam may be modified in a size and direction that offsets the pattern position error for each position of the target pattern to perform the exposure process. For example, the exposure beam may be an electron beam (E-beam).

[0106] After that, in step 7 (S70), control signals (CMD, CID) are applied based on the measurement recipe and inspection recipe generated in step 5 (S50) to measure and inspect the photomask based on the correction layout (CL).

[0107] Although the present invention has been described above with reference to embodiments thereof, those skilled in the art will understand that various modifications and changes can be made to the invention without departing from the spirit and scope of the invention as described in the following claims. Explanation of the symbols

[0108] 10: Substrate 12: Mask substrate 14: Shade 16: Photosensitive film 100: Exposure device 110: Investigation device 120: Biaser 122, 124, 126: Deflection structures 200: Control unit 210: Data receiver 220: Data Correction Section 230: Output section 300: Registration Tool 400: Wafer measuring device 500: Photomask measuring device 600: Photomask inspection device TL: Target Layout CL: Correction Layout RM: Position Error Correction Map OED: Overlay Error Data

Claims

Claim 1 A method for manufacturing a photomask comprising: designing a target layout having a target pattern to be implemented in a photomask; generating a registration correction map by reflecting overlay error data of a wafer; generating a correction layout by reflecting the registration correction map in the target layout; forming the photomask by performing an exposure process, a development process, and an etching process on a blank mask; and inspecting the photomask based on inspection conditions set based on the correction layout. Claim 2 A method for manufacturing a photomask according to claim 1, further comprising measuring the photomask based on measurement conditions set based on the correction layout. Claim 3 A method for manufacturing a photomask according to claim 2, wherein measuring the photomask comprises generating a measurement recipe based on the correction layout that includes measurement conditions for measuring at least one of the critical dimension and positional error of patterns formed on the photomask, and applying a measurement control signal reflecting the measurement recipe to a measuring device. Claim 4 A method for manufacturing a photomask according to claim 2, wherein measuring the photomask comprises extracting a portion of the correction layout to generate a reference image for measuring at least one of the critical dimension and positional error of the photomask. Claim 5 A method for manufacturing a photomask according to claim 1, wherein inspecting the photomask comprises generating an inspection recipe including inspection conditions for inspecting the photomask based on the correction layout, and applying an inspection control signal reflecting the inspection recipe to an inspection device. Claim 6 A method for manufacturing a photomask according to claim 1, wherein generating the correction layout comprises identifying the position error of the target layout from the position error correction map, generating the correction layout by translating each of the first sub-patterns included in the target layout to minimize the position error, generating a verification layout by applying the translation inversely to each of the second sub-patterns included in the correction layout, and verifying the correction layout by comparing the target layout and the verification layout. Claim 7 A method for manufacturing a photomask according to claim 1, wherein generating the position error correction map comprises forming a circuit pattern on the wafer based on the target layout; measuring an overlay error from the circuit pattern on the wafer to obtain overlay error data; and performing modeling based on the overlay error data. Claim 8 A method for manufacturing a photomask according to claim 1, wherein forming the photomask comprises: performing an exposure process on the blank mask by reflecting the position error correction map; and performing a development process and an etching process on the blank mask. Claim 9 A method for manufacturing a photomask according to claim 8, wherein performing an exposure process on the blank mask comprises providing an exposure device including an irradiation device for irradiating an exposure beam and a deflector for controlling the direction of travel of the exposure beam, and changing the direction of travel of the exposure beam through the deflector of the exposure device by reflecting the target layout and the position error correction map. Claim 10 A method for manufacturing a photomask comprising: designing a target layout having a target pattern to be implemented in a photomask; forming a circuit pattern on a wafer based on the target layout; measuring an overlay error from the circuit pattern on the wafer to obtain overlay error data; performing modeling based on the overlay error data; generating a registration correction map by reflecting the overlay error data on the wafer; generating a correction layout by reflecting the registration correction map on the target layout of the photomask; performing an exposure process, a development process, and an etching process on a blank mask to form the photomask; and measuring the photomask based on measurement conditions set based on the correction layout.

Images