Coating film evaluation method, coating film evaluation apparatus, and computer program

Abstract

This technology provides a method for appropriately evaluating a coated film based on its measured film thickness distribution. [Solution] The edge cut width setting unit (913) sets the first and second edge cut widths. The feature calculation unit (915) obtains a first feature from the film thickness distribution, excluding the film thickness in the edge region of the first edge cut width, and a second feature from the distribution excluding the film thickness in the edge region of the second edge cut width. The determination unit 916 determines whether the first feature of the first edge cut width is acceptable or unacceptable based on the acceptance criteria. If the determination unit (916) determines that it is unacceptable, the cost value calculation unit (917) inputs the first feature into the first cost function and calculates the cost value. If the determination unit (916) determines that it is acceptable, the cost value calculation unit (917) inputs the second feature into the second cost function and calculates the cost value. The output of the second cost function is less than or equal to the output of the first cost function.

Description

Technical Field

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[0001] The subject matter disclosed in this specification relates to a technique for evaluating a coating film formed on a substrate.

Background Art

[0002] In the manufacturing process of flat panel displays, a device called a coater is used. A coater is a device that discharges a processing liquid from a slit nozzle by a pump and applies the processing liquid to the entire substrate being conveyed. With such coaters, in recent years with the improvement in product quality, it has been required to apply the processing liquid so that the film thickness of the processing liquid becomes uniform over the entire substrate.

[0003] For example, in Patent Document 1, it is disclosed that by repeatedly measuring the discharge characteristics when discharging the processing liquid, parameters for controlling the pump are adjusted for optimization. Also, in Patent Document 2, it is disclosed that a feature amount is calculated from the discharge pressure waveform and the discharge pressure waveform is evaluated based on this feature amount.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the prior art, a method for evaluating the film thickness distribution of the coating film actually formed on the substrate has not been sufficiently considered.

[0006] An object of the present invention is to provide a technique capable of appropriately evaluating a coating film based on the measured film thickness distribution.

Means for Solving the Problems

[0007] To solve the above problems, the first embodiment is a coating film evaluation method for evaluating a coating film applied to a substrate, comprising: a) a film thickness distribution acquisition step of acquiring the film thickness distribution of the coating film formed on the substrate; b) an edge cut width setting step of setting a first edge cut width and a second edge cut width, which are width dimensions of the region extending inward from the edge of the substrate and are different from each other; c) a judgment step of determining whether to pass or fail based on an acceptance criterion value for a first feature quantity of the film thickness distribution excluding the film thickness in the region of the first edge cut width; d) a first cost value calculation step of inputting the first feature quantity into a first cost function and calculating a cost value if it is determined to fail in step c); and e) a second cost value calculation step of inputting a second feature quantity of the film thickness distribution excluding the film thickness in the region of the second edge cut width into a second cost function and calculating a cost value if it is determined to pass in step c), wherein the output of the second cost function is less than or equal to the output of the first cost function.

[0008] The second aspect is the coating film evaluation method of the first aspect, wherein the first edge cut width is greater than the second edge cut width.

[0009] A third aspect is a coating film evaluation method according to the first or second aspect, wherein the output of the first cost function takes a minimum value when the first feature quantity satisfies the acceptance criterion value, and increases as the first feature quantity moves further away from the acceptance criterion value.

[0010] The fourth aspect is the coating film evaluation method of the third aspect, wherein the maximum value of the output of the second cost function coincides with the minimum value of the output of the first cost function.

[0011] The fifth aspect is a coating film evaluation method according to any of the first to fourth aspects, wherein the first feature quantity and the second feature quantity include the range of variation in film thickness.

[0012] The sixth aspect is a coating film evaluation method according to any of the first to fifth aspects, wherein the first feature quantity and the second feature quantity include the difference between a representative value of the film thickness in the edge region of the coating film and a representative value of the film thickness in the central region inside the edge region.

[0013] The seventh embodiment is a coating film evaluation apparatus for evaluating a coating film applied to a substrate, comprising: a film thickness distribution acquisition unit for acquiring the film thickness distribution of a coating film formed on a substrate; an edge cut width setting unit for setting a first edge cut width and a second edge cut width, which are different width dimensions of edge regions extending inward from the edge of the substrate; a feature quantity calculation unit for calculating a first feature quantity of the film thickness distribution excluding the film thickness of the edge region of the first edge cut width, and a second feature quantity of the distribution excluding the film thickness of the edge region of the second edge cut width; a determination unit for determining whether the first feature quantity of the first edge cut width is acceptable or unacceptable based on an acceptance criterion value; and a cost value calculation unit that, if the determination unit determines it is unacceptable, inputs the first feature quantity into a first cost function to calculate a cost value, and if the determination unit determines it is acceptable, inputs the second feature quantity into a second cost function to calculate a cost value, wherein the output of the second cost function is less than or equal to the output of the first cost function.

[0014] The eighth aspect is a computer program that causes a computer to execute the coating film evaluation method of the first or second aspect. [Effects of the Invention]

[0015] According to the first to eighth embodiments, a single cost value is calculated based on the film thickness distribution of the coated film, excluding the film thickness in each region of the first and second edge cut widths, which are different from each other. This allows for the integration of evaluations for cases where the edge cut width is large and for cases where it is small. Furthermore, since the output of the second cost function used when the first edge cut width is acceptable is less than or equal to the output of the first cost function used when it is unacceptable, the cost value when the first edge cut width is acceptable can be made smaller than when it is unacceptable. As a result, an appropriate cost value can be calculated according to the pass / fail judgment, and the film thickness distribution of the coated film can be appropriately evaluated.

[0016] According to the coating film evaluation method of the second embodiment, as the edge cut width increases, film thicknesses with large variations can be excluded. Therefore, based on the pass / fail status of the first edge cut width, which tends to improve uniformity, an appropriate cost value can be calculated by selecting either a first cost function with a large output or a second cost function with a small output.

[0017] According to the coating film evaluation method of the third embodiment, the cost value decreases when the first feature quantity is close to the acceptance standard value, and increases as it deviates from the acceptance standard value, so that the coating film can be appropriately evaluated based on the cost value.

[0018] According to the coating film evaluation method of the fourth embodiment, it is possible to avoid discontinuity between the range of cost values ​​output from the first cost function and the range of cost values ​​output from the second cost function. Therefore, continuity can be ensured in the output cost values, and the coating film can be appropriately evaluated based on the cost values.

[0019] According to the coating film evaluation method of the fifth embodiment, the uniformity of the film thickness of the coating film can be appropriately evaluated.

[0020] According to the coating film evaluation method of the sixth embodiment, the variation in film thickness in the edge region relative to the film thickness in the central region can be appropriately evaluated. [Brief explanation of the drawing]

[0021] [Figure 1] This is a diagram schematically showing the overall configuration of the coating apparatus according to the first embodiment. [Figure 2] This is a diagram showing the configuration of the processing liquid supply mechanism included in the coating apparatus. [Figure 3] This is a block diagram showing the configuration of the control unit. [Figure 4] This is a top view showing the upper surface of the substrate. [Figure 5] This is a diagram showing an example of the film thickness distribution acquired by the film thickness distribution acquisition unit. [Figure 6] This is a diagram conceptually showing the calculation method of the start-side feature amount, which is an example of the feature amount. [Figure 7] This is a diagram conceptually showing the calculation method of the end-side feature amount, which is another example of the feature amount. [Figure 8] This is a diagram showing an example of the cost function used when two edge cuts are set. [Figure 9] This is a diagram showing the procedure for calculating the cost value for evaluating the coating film. [Figure 10] This is a diagram showing an example of the cost function used when three edge cut widths are set.

Mode for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that in the drawings, for ease of understanding, the dimensions and numbers of each part may be exaggerated or simplified.

[0023] <1. First Embodiment> FIG. 1 is a diagram schematically showing the overall configuration of a coating apparatus 1 according to the first embodiment. The coating apparatus 1 is a substrate processing apparatus that discharges a processing liquid onto the upper surface Sf of a substrate S to form a coating film on the substrate S. The coating apparatus 1 is, for example, a slit coater. As will be described later, the coating apparatus 1 has a control unit 9 having a function as a film thickness evaluation apparatus for evaluating the film thickness.

[0024] The substrate S is, for example, a glass substrate for a liquid crystal display device. The substrate S may also be various types of substrates for electronic devices, such as semiconductor wafers, photomask glass substrates, plasma display glass substrates, magnetic / optical disk glass or ceramic substrates, organic EL glass substrates, solar cell glass or silicon substrates, and other flexible substrates and printed circuit boards.

[0025] In Figure 1, an XYZ coordinate system is defined to explain the arrangement of each element of the coating apparatus 1. The transport direction Dt of the substrate S is the "X direction". In the X direction, the direction in which the substrate S moves (downstream of the transport direction Dt) is the +X direction, and the opposite direction (upstream of the transport direction Dt) is the -X direction. Also, the direction perpendicular to the X direction is the Y direction, and the direction perpendicular to both the X and Y directions is the Z direction. In the following explanation, the Z direction will be considered the vertical direction, and the X and Y directions will be considered the horizontal directions. In the Z direction, the +Z direction will be considered the upward direction, and the -Z direction will be considered the downward direction. Note that these directions do not limit the arrangement of the coating apparatus.

[0026] The coating apparatus 1 comprises, in order in the +X direction, an input conveyor 100, an input transfer unit 2, a floating stage unit 3, an output transfer unit 4, and an output conveyor 110. The input conveyor 100, the input transfer unit 2, the floating stage unit 3, the output transfer unit 4, and the output conveyor 110 form a transport path through which the substrate S passes. The coating apparatus 1 further comprises a substrate transport unit 5, a coating mechanism 7, a processing liquid supply mechanism 8, and a control unit 9.

[0027] The substrate S is transported to the input conveyor 100 from equipment upstream of the coating apparatus 1. The input conveyor 100 is equipped with a roller conveyor 101 and a rotary drive mechanism 102. The rotary drive mechanism 102 rotates each roller of the roller conveyor 101. The rotation of each roller of the roller conveyor 101 transports the substrate S downstream (+X direction) in a horizontal position. "Horizontal position" refers to a state in which the main surface (the surface with the largest area) of the substrate S is parallel to the horizontal plane (XY plane).

[0028] The input transfer unit 2 includes a roller conveyor 21 and a rotation / lifting drive mechanism 22. The rotation / lifting drive mechanism 22 rotates each roller of the roller conveyor 21 and also raises and lowers the roller conveyor 21. The rotation of the roller conveyor 21 transports the substrate S downstream (+X direction) in a horizontal position. The raising and lowering of the roller conveyor 21 changes the position of the substrate S in the Z direction. The substrate S is transferred from the input conveyor 100 to the levitation stage unit 3 via the input transfer unit 2.

[0029] As shown in Figure 1, the levitation stage section 3 is substantially flat. The levitation stage section 3 is divided into three sections along the X direction. The levitation stage section 3 comprises, in order toward the +X direction, an inlet levitation stage 31, a coating stage 32, and an outlet levitation stage 33. The upper surfaces of the inlet levitation stage 31, the coating stage 32, and the outlet levitation stage 33 are on the same plane. The levitation stage section 3 further comprises a lift pin drive mechanism 34, a levitation control mechanism 35, and a lifting drive mechanism 36. The lift pin drive mechanism 34 raises and lowers a plurality of lift pins located on the inlet levitation stage 31. The levitation control mechanism 35 supplies compressed air for levitating the substrate S to the inlet levitation stage 31, the coating stage 32, and the outlet levitation stage 33. The lifting drive mechanism 36 raises and lowers the outlet levitation stage 33.

[0030] Numerous ejection holes for ejecting compressed air supplied from the levitation control mechanism 35 are arranged in a matrix on the upper surfaces of the inlet levitation stage 31 and the outlet levitation stage 33. When compressed air is ejected from each ejection hole, the substrate S levitates upward relative to the levitation stage 3. As a result, the lower surface Sb of the substrate S separates from the upper surface of the levitation stage 3, and the substrate S is supported in a horizontal position. When the substrate S is levitated, the distance between the lower surface Sb of the substrate S and the upper surface of the levitation stage 3 (levitation amount) is, for example, 10 μm to 500 μm.

[0031] The upper surface of the coating stage 32 is provided with ejection holes for ejecting compressed air supplied from the levitation control mechanism 35 and suction holes for drawing in gas. The ejection holes and suction holes are arranged alternately in the X and Y directions. The levitation control mechanism 35 controls the amount of compressed air ejected from the ejection holes and the amount of air drawn in from the suction holes. This precisely controls the amount of levitation of the substrate S relative to the coating stage 32 so that the position of the upper surface Sf of the substrate S passing above the coating stage 32 in the Z direction is a specified value. The amount of levitation of the substrate S relative to the coating stage 32 is calculated by the control unit 9 based on the detection results of the sensor 61 or sensor 62, which will be described later. Furthermore, the amount of levitation of the substrate S relative to the coating stage 32 is preferably adjustable with high precision by airflow control.

[0032] The substrate S, which has been brought into the levitation stage section 3, is propelled in the +X direction by the roller conveyor 21 and transported onto the inlet levitation stage 31. The inlet levitation stage 31, coating stage 32, and outlet levitation stage 33 support the substrate S in a levitated state. For example, the configuration described in Japanese Patent No. 5346643 can be used for the levitation stage section 3.

[0033] The substrate transport unit 5 is located below the levitation stage unit 3. The substrate transport unit 5 comprises a chuck mechanism 51 and a suction / travel control mechanism 52. The chuck mechanism 51 is equipped with a suction pad (not shown) provided on a suction member. The chuck mechanism 51 supports the substrate S from below by bringing the suction pad into contact with the peripheral edge of the lower surface Sb of the substrate S. The suction / travel control mechanism 52 applies negative pressure to the suction pad to attract the substrate S to the suction pad. The suction / travel control mechanism 52 also causes the substrate transport unit 5 to reciprocate in the X direction.

[0034] The chuck mechanism 51 holds the substrate S such that its lower surface Sb is positioned higher than the upper surface of the levitation stage 3. With its peripheral edge held by the chuck mechanism 51, the substrate S maintains a horizontal position due to the buoyancy provided by the levitation stage 3.

[0035] As shown in Figure 1, the coating apparatus 1 is equipped with a sensor 61 for measuring the plate thickness. The sensor 61 is positioned near the roller conveyor 21. The sensor 61 detects the position in the Z direction of the upper surface Sf of the substrate S held by the chuck mechanism 51. Furthermore, by positioning a chuck (not shown) that is not holding the substrate S directly below the sensor 61, the sensor 61 can detect the position in the vertical Z direction of the suction surface, which is the upper surface of the suction member.

[0036] The chuck mechanism 51 moves in the +X direction while holding the substrate S that has been brought into the levitation stage section 3. As a result, the substrate S is transported from above the inlet levitation stage 31, through above the coating stage 32, to above the outlet levitation stage 33. Then, the substrate S is moved from the outlet levitation stage 33 to the output transfer section 4.

[0037] The output transfer unit 4 moves the substrate S from a position above the exit floating stage 33 to the output conveyor 110. The output transfer unit 4 includes a roller conveyor 41 and a rotation / lifting drive mechanism 42. The rotation / lifting drive mechanism 42 rotates the roller conveyor 41 and also moves the roller conveyor 41 up and down along the Z direction. As each roller of the roller conveyor 41 rotates, the substrate S moves in the +X direction. Also, as the roller conveyor 41 moves up and down, the substrate S is displaced in the Z direction.

[0038] The output conveyor 110 comprises a roller conveyor 111 and a rotary drive mechanism 112. The output conveyor 110 transports the substrate S in the +X direction by the rotation of each roller of the roller conveyor 111, and discharges the substrate S outside the coating apparatus 1. The input conveyor 100 and the output conveyor 110 are part of the coating apparatus 1. However, the input conveyor 100 and the output conveyor 110 may be incorporated into a separate apparatus from the coating apparatus 1.

[0039] The coating mechanism 7 coats the upper surface Sf of the substrate S with processing liquid. The coating mechanism 7 is positioned above the transport path of the substrate S. The coating mechanism 7 has a nozzle 71. The nozzle 71 is a slit nozzle with a slit-shaped discharge port on its lower surface. The nozzle 71 is connected to a positioning mechanism (not shown). The positioning mechanism moves the nozzle 71 between a coating position above the coating stage 32 (indicated by a solid line in Figure 1) and a maintenance position, which will be described later. The processing liquid supply mechanism 8 is connected to the nozzle 71. The processing liquid supply mechanism 8 supplies processing liquid to the nozzle 71, causing the processing liquid to be discharged from a discharge port located on the lower surface of the nozzle 71.

[0040] Figure 2 shows the configuration of the processing liquid supply mechanism 8 provided in the coating apparatus 1. The processing liquid supply mechanism 8 includes a pump 81, piping 82, a processing liquid replenishment unit 83, piping 84, an on-off valve 85, a pressure sensor 86, and a drive unit 87. The pump 81 is a supply source for supplying the processing liquid to the nozzle 71, and supplies the processing liquid by volume change. For the pump 81, for example, a bellows-type pump as described in Japanese Patent Application Publication No. 10-61558 can be used. As shown in Figure 2, the pump 81 has a flexible tube 811 that can elastically expand and contract in the radial direction. One end of the flexible tube 811 is connected to the processing liquid replenishment unit 83 via piping 82. The other end of the flexible tube 811 is connected to the nozzle 71 via piping 84.

[0041] Pump 81 has a bellows 812 that is elastically deformable in the axial direction. The bellows 812 has a small bellows section 813, a large bellows section 814, a pump chamber 815, and an operating disk section 816. The pump chamber 815 is located between the flexible tube 811 and the bellows 812. An incompressible medium is sealed inside the pump chamber 815. The operating disk section 816 is connected to the drive unit 87.

[0042] The processing liquid replenishment unit 83 has a storage tank 831 for storing processing liquid. The storage tank 831 is connected to the pump 81 via piping 82, and an on-off valve 833 is inserted into the piping 82. The on-off valve 833 opens and closes in response to commands from the control unit 9. When the on-off valve 833 is open, processing liquid can be supplied from the storage tank 831 to the flexible tube 811 of the pump 81. When the on-off valve 833 is closed, the supply of processing liquid from the storage tank 831 to the flexible tube 811 of the pump 81 is restricted.

[0043] The piping 84 is connected to the output side of the pump 81. An on-off valve 85 is provided on the piping 84. The on-off valve 85 opens and closes the piping 84 in response to a command from the control unit 9. When the on-off valve 85 is operated, the supply of processing liquid to the nozzle 71 is switched on and off. A pressure sensor 86 is located on the piping 84. The pressure sensor 86 detects the pressure (discharge pressure) applied to the processing liquid supplied to the nozzle 71 and outputs a signal indicating the detected pressure value to the control unit 9.

[0044] As shown in Figures 1 and 2, a sensor 62 is positioned on the nozzle 71 to which the processing liquid is supplied from the processing liquid supply mechanism 8. The sensor 62 non-contactually detects the height of the substrate S in the Z direction. The sensor 62 is electrically connected to the control unit 9. Based on the detection result of the sensor 62, the control unit 9 measures the distance (separation distance) between the floating substrate S and the upper surface of the coating stage 32. Then, based on the measured separation distance, the control unit 9 adjusts the coating position of the nozzle 71 by the positioning mechanism. For example, an optical sensor or an ultrasonic sensor can be used for the sensor 62.

[0045] The substrate S, which is discharged from the output conveyor 110, is dried in a drying device or the like to form a coating film. The substrate S with the coated film is then transported to the film thickness measuring instrument AP1 as needed, as shown in Figure 1, to measure the film thickness. For example, a spectroscopic ellipsometer or an X-ray reflectance measuring device can be used as the film thickness measuring instrument AP1.

[0046] The coating mechanism 7 includes a nozzle cleaning standby unit 72. The nozzle cleaning standby unit 72 performs predetermined maintenance on the nozzle 71 positioned at the maintenance location. The nozzle cleaning standby unit 72 includes a roller 721, a cleaning section 722, and a roller butt 723. The nozzle cleaning standby unit 72 prepares the nozzle 71's discharge port for coating by cleaning and forming a liquid reservoir.

[0047] Figure 3 is a block diagram showing the configuration of the control unit 9. The control unit 9 controls the operation of each component in the coating apparatus 1. The control unit 9 is a computer equipped with a processor 91 and memory 93. The processor has, for example, a CPU (Central Processing Unit). The memory 93 has transient storage devices such as RAM (Random Access Memory). The memory 93 may also have non-transient storage devices such as an HDD (Hard Disk Drive) or an SSD (Solid State Drive). The memory 93 is connected to the processor 91 via bus wiring.

[0048] The control unit 9 includes a display device 95 for displaying various information and an input device 97 for receiving user commands. The display device 95 and the input device 97 are connected to the processor 91 via a wiring bus. The display device 95 is, for example, a liquid crystal display. The input device 97 is, for example, a mouse or keyboard. The display device 95 can also function as an input device if it has a touch panel.

[0049] The memory 93 stores the computer program 931. The computer program 931 is provided to the control unit 9 via the recording medium M. That is, the recording medium M contains the computer program 931 in a format readable by the control unit 9. The recording medium M can be, for example, a USB (Universal Serial Bus) memory, an optical disc such as a DVD (Digital Versatile Disc), or a magnetic disc.

[0050] The processor 91 functions as a discharge control unit 910, a film thickness distribution acquisition unit 911, an edge cut width setting unit 913, a feature quantity calculation unit 915, a determination unit 916, a cost value calculation unit 917, and an optimization unit 919 by executing the computer program 931. The control unit 9 functions as a coating film evaluation device that evaluates the coating film by calculating a cost value using the film thickness distribution acquisition unit 911, the edge cut width setting unit 913, the feature quantity calculation unit 915, the determination unit 916, and the cost value calculation unit 917.

[0051] The discharge control unit 910 controls the operation of the pump 81 that supplies the processing liquid to the nozzle 71 based on preset control parameters. The control parameters are, for example, setting values ​​for pump control, and specifically are various parameters that define the movement of the operating disk unit 816 (for example, acceleration time, steady speed, time to maintain steady speed, deceleration time, etc.). As will be described later, the control parameters are optimized by the optimization unit 919 based on the cost value calculated by the cost value calculation unit 917.

[0052] The film thickness distribution acquisition unit 911 acquires the film thickness distribution, which is the measurement result of the coating film formed on the substrate S. The film thickness distribution of the coating film is measured by the film thickness measuring instrument AP1. The film thickness distribution acquisition unit 911 stores the acquired film thickness distribution in the memory 93.

[0053] Figure 4 is a top view showing the top surface Sf of the substrate S. As shown in Figure 4, in this embodiment, the film thickness measuring instrument AP1 measures the film thickness distribution on a reference line Ln set on the substrate S. The reference line Ln extends parallel to the direction that coincides with the transport direction Dt (X direction) of the substrate S during the coating process of the coating apparatus 1. That is, the reference line Ln coincides with the direction in which the processing liquid is applied to the substrate S (the direction in which the coated film is formed). However, the reference line Ln does not have to coincide with the coating direction, and may, for example, coincide with the diagonal of the substrate S. Also, it is not necessary for the reference line Ln to pass through the center CP, and may, for example, be set at a position closer to one end of the substrate S.

[0054] The edge cut width setting unit 913 sets the edge cut width C, which is the width dimension of the edge cut region AE that extends inward from the edge (periphery) of the substrate S. As shown in Figure 4, the edge cut region AE is an annular shape (here, a rectangular frame shape) that extends inward from the edge of the substrate S by the edge cut width C. The area a few millimeters inward from the edge of the substrate S includes parts where no coating film is formed and the edges of the coating film, so the film thickness distribution is uneven and may not be suitable for evaluating the uniformity of the film thickness. Therefore, in order to exclude the film thickness distribution of the edge cut region AE from the overall film thickness distribution (edge ​​cut), the edge cut width C, which is the width dimension of the edge cut region AE, is set in advance. Note that the edge cut width C may be specified as appropriate by the user or may be defined by the computer program 931. In this embodiment, the edge cut width setting unit 913 can set multiple edge cut widths C. In this embodiment, the edge cut width setting unit 913 sets two different edge cut widths C, namely edge cut width C1 (first edge cut width) and edge cut width C2 (second edge cut width). Note that edge cut width C2 is smaller than edge cut width C1 (i.e., C1 > C2).

[0055] The feature calculation unit 915 calculates feature quantities from the film thickness distribution acquired by the film thickness distribution acquisition unit 911. Specifically, the feature calculation unit 915 calculates feature quantities for the target film thickness distribution. The target film thickness distribution is the film thickness distribution in the target region AT of the upper surface Sf of the substrate S, excluding the edge cut region AE. In other words, the target film thickness distribution is the remaining film thickness distribution obtained by the film thickness distribution acquisition unit 911, excluding the film thickness of the edge cut region AE.

[0056] Figure 5 shows an example of the film thickness distribution TD acquired by the film thickness distribution acquisition unit 911. In Figure 5, the horizontal axis represents the position on the substrate S (specifically, the position on the reference line Ln), and the vertical axis represents the film thickness. As shown in Figure 5, the substrate S is divided into three regions: the coating start region PS, the coating center region PC, and the coating end region PE. The coating start region PS is the edge region from the upstream end of the substrate S to position pos_s, and corresponds to the part where the processing liquid is first applied to the substrate S. The coating end region PE is the edge region from position pos_e to the downstream end of the substrate S, and corresponds to the part where the application of the processing liquid is completed. Position pos_e is located downstream of position pos_s. The coating center region PC is the region located between the coating start region PS and the coating end region PE.

[0057] As shown in Figure 5, in the coating start region PS, the film thickness distribution TD rises sharply from zero, then fluctuates upward and downward before converging to a nearly constant size. In the coating middle region PC, the film thickness distribution TD remains nearly constant. In the coating end region PE, the film thickness distribution TD fluctuates upward from a constant state and then decreases sharply towards zero.

[0058] The feature calculation unit 915 first acquires the target film thickness distribution in order to obtain the features of the target film thickness distribution. To do this, it obtains a distribution (target film thickness distribution TTD) by excluding the film thickness of the regions corresponding to the multiple edge cut widths C set by the edge cut width setting unit 913 (edge ​​cut region AE) from the overall film thickness distribution TD. Then, the feature calculation unit 915 calculates feature quantities x from the target film thickness distribution TTD. In this embodiment, as shown in Figure 5, the feature calculation unit 915 acquires the target film thickness distribution TTD1 for edge cut width C1 and the target film thickness distribution TTD2 for edge cut width C2, respectively. Then, the feature calculation unit 915 calculates feature quantities x1 (first feature quantity) and feature quantities x2 (second feature quantity), respectively, based on the target film thickness distributions TTD1 and TTD2.

[0059] Next, the calculation methods for features x1 and x2 will be explained with reference to Figures 6 and 7. Figure 6 is a conceptual diagram showing the calculation method for the initial feature RD_s, which is an example of features x1 and x2. The initial feature RD_s is a feature mainly calculated based on the film thickness distribution within the coating start region PS. The initial feature RD_s is the sum of the initial film thickness variation range R_s and the initial difference Diff_s. The initial film thickness variation range R_s is the variation range of film thickness within the coating start region PS (the difference between the maximum and minimum values). The initial difference Diff_s is the difference between the average film thickness Th_s within the coating start region PS and the average film thickness Th_c within the coating center region PC. Note that other representative values ​​such as the median or mode of film thickness may be used instead of the average film thickness. Furthermore, the starting feature RD_s is not limited to the sum of the starting film thickness variation R_s and the starting difference Diff_s; for example, it may be the sum of these values ​​divided by the average film thickness.

[0060] Figure 7 conceptually illustrates the calculation method for the termination feature RD_e, another example of feature quantities x1 and x2. As shown in Figure 7, the termination feature RD_e is a feature quantity mainly calculated from the film thickness distribution within the coating termination region PE. The termination feature RD_e is the sum of the termination film thickness variation range R_e and the termination difference Diff_e. The termination film thickness variation range R_e is the variation range of film thickness within the coating termination region PE. The termination difference Diff_e is the difference between the average film thickness Th_e within the coating termination region PE and the average film thickness Th_c within the coating central region PC.

[0061] Returning to Figure 3, the determination unit 916 determines whether the feature quantity x1 calculated by the feature quantity calculation unit 915 is acceptable or unacceptable. In this embodiment, a pass / fail criterion value P1 for determining whether the feature quantity x1 is acceptable or unacceptable is set in advance. The pass / fail criterion value P1 may be set in advance on the computer program 931, or it may be set based on user input. The determination unit 916 compares the feature quantity x1 with the pass / fail criterion value P1 and determines that the feature quantity x1 is acceptable if it is less than or equal to the pass / fail criterion value P1, and unacceptable if the feature quantity x1 exceeds the pass / fail criterion value P1. A pass / fail criterion value P2 corresponding to feature quantity x2 may also be set in advance.

[0062] The cost value calculation unit 917 calculates the cost value based on the feature F calculated by the feature calculation unit 915. The cost value is calculated by inputting the feature into the cost function. Details of the cost function will be described later.

[0063] The optimization unit 919 optimizes the control parameters based on the cost value calculated by the cost value calculation unit 917. The cost value output by the cost function approaches zero as the film thickness condition improves. The optimization unit 919 optimizes the control parameters so that the cost value is minimized. Nonlinear programming, genetic algorithms, or Bayesian optimization can be used as optimization methods.

[0064] Figure 8 shows an example of a cost function used when two edge cut widths C1 and C2 are set. In Figure 8, the horizontal axis represents the feature x1 corresponding to edge cut width C1 or the feature x2 corresponding to edge cut width C2, and the vertical axis represents the cost value.

[0065] In this embodiment, cost functions f1 and f2 are set. Cost function f1 is a function that takes feature x1 as input and outputs a cost value. Cost function f2 is a function that takes feature x2 as input and outputs a cost value. Feature quantities x1 and x2 may be, for example, the starting feature RD_s or the ending feature RD_e. Alternatively, feature quantities x1 and x2 may be a weighted sum of the starting feature RD_s and the ending feature RD_e.

[0066] As shown in Figure 8, the output of the cost function f1 takes its minimum value A when the feature x1 corresponding to the edge cut width C1 is acceptable (i.e., when the feature x1 is less than or equal to the acceptable threshold P1). Furthermore, the output of the cost function f1 increases as the feature x1 moves further away from the acceptable threshold P1, and here it increases monotonically with a positive slope a. The cost function f1 is expressed by the following equation (1).

[0067]

number

[0068] Next, the cost function f2 will be explained. The output of the cost function f2 is set to be less than or equal to the output of the cost function f1. In this embodiment, the maximum value of the output of the cost function f2 coincides with A, which is the minimum value of the output of the cost function f1. The output of the cost function f2 takes its maximum value A when the feature x2 is greater than or equal to the saturation feature s1. The saturation feature s1 is a value greater than the passing threshold P2 for the feature x2. The cost function f2 increases monotonically upward with a positive slope b from zero to the saturation feature s1. The output of the cost function f2 takes a cost value B when the feature x2 is at the passing threshold P2. The cost function f2 is expressed by the following equation (2).

[0069]

number

[0070] As described later, the cost value calculation unit 917 calculates the cost value using either the cost function f1 or f2, depending on the determination result of the determination unit 916. Specifically, if the determination unit 916 determines that the feature x1 of the edge cut width C1 is acceptable (i.e., x1 ≤ P1), the cost value calculation unit 917 inputs the feature x2 into the cost function f2 and calculates the cost value. On the other hand, if the determination unit 916 determines that the feature x1 is unacceptable (i.e., x1 > P1), the cost value calculation unit 917 inputs the feature x1 into the cost function f1 and calculates the cost value.

[0071] Figure 9 shows the procedure for calculating a cost value for evaluating a coated film. The processing procedure shown in Figure 9 is an example of a coated film evaluation method performed by the control unit 9. The order of each process shown in Figure 9 can be changed arbitrarily, as long as no inconsistencies arise. That is, if a particular process does not depend on other processes, the order of these processes may be changed, or these processes may be executed in parallel.

[0072] First, the film thickness distribution acquisition unit 911 acquires the film thickness distribution TD of the coating applied to the substrate S (film thickness distribution acquisition step S1). Next, the edge cut width setting unit 913 sets the edge cut widths C1 and C2 (edge ​​cut width setting step S2). In the edge cut width setting step S2, the acceptance criteria values ​​P1 and P2, and the cost functions f1 and f2 are also set for the feature quantities x1 and x2. However, the acceptance criteria value P2 is not mandatory.

[0073] After the edge cut width setting step S2, the feature calculation unit 915 calculates feature quantities x1 and x2 based on the edge cut widths C1 and C2 (feature calculation step S3). After feature quantities x1 and x2 are calculated, the judgment unit 916 determines whether feature quantity x1 is acceptable or not (judgment step S4). If feature quantity x1 is acceptable (i.e., x1 ≤ P1), the cost value calculation unit 917 inputs feature quantity x2 into the cost function f2 and calculates the cost value (cost value calculation step S5). On the other hand, if feature quantity x1 is unacceptable (i.e., x1 > P1), the cost value calculation unit 917 inputs feature quantity x1 into the cost function f1 and calculates the cost value (cost value calculation step S6).

[0074] It is not mandatory to calculate feature x2 in the feature calculation step S3. For example, feature x2 may be calculated in the cost value calculation step S5, which is after the judgment step S4. By shifting the timing of feature x2 calculation to a later stage, the processing load can be distributed, and the necessary resources can be managed appropriately. This improves the performance of the coating film evaluation apparatus.

[0075] <Summary> As described above, the coating film evaluation method of this embodiment includes: a) a film thickness distribution acquisition step (S1) for acquiring the film thickness distribution TD of the coating film formed on the substrate S; b) an edge cut width setting step (S2) for setting two different first edge cut widths (C1) and second edge cut widths (C2) that are width dimensions of the region extending inward from the edge of the substrate S; and c) a first feature quantity (x1) of the remaining distribution (TTD1) of the film thickness distribution TD, excluding the film thickness in the region (AE) of the first edge cut width (C1), based on an acceptance criterion value (P1). The process includes a judgment step (S4) for determining whether the product passes or fails, a first cost value calculation step (S6) in which, if the product fails in the judgment step (S4), the first feature quantity (x1) is input into the first cost function (f1) to calculate the cost value, and a second cost value calculation step (S5) in which, if the product passes in the judgment step (S4), the second feature quantity (x2) of the film thickness distribution (TTD2) excluding the film thickness in the region (AE) of the second edge cut width (C2) is input into the second cost function (f2) to calculate the cost value. Here, the output of the second cost function (f2) is less than or equal to the output of the first cost function (f1).

[0076] In this configuration, a single cost value is calculated based on each distribution (TTD1, TTD2) of the coating film thickness distribution TD, excluding the film thickness in each edge-cut region of two different edge-cut widths C1 (first edge-cut width) and C2 (second edge-cut width). This allows for an integrated evaluation of cases where the edge-cut width is large and cases where it is small. Furthermore, the output of the second cost function (f2), used when the edge-cut width (C1) is acceptable, is less than or equal to the output of the first cost function (f1), used when the edge-cut width (C1) is unacceptable. Therefore, the cost value when the first edge-cut width (C1) is acceptable can be made smaller than when it is unacceptable. This allows for the calculation of an appropriate cost value according to the pass / fail judgment, thus enabling a proper evaluation of the coating film thickness distribution.

[0077] Furthermore, the first edge cut width (C1) is larger than the second edge cut width (C2). Generally, the larger the edge cut width, the higher the uniformity of the film thickness. Therefore, by selecting either the first cost function (f1) with a large output or the second cost function (f2) with a small output based on the pass / fail status of the first edge cut width (C1), which tends to result in a higher uniformity evaluation, an appropriate cost value can be calculated.

[0078] Furthermore, the output of the first cost function (f1) takes its minimum value (A) when the first feature (x1) satisfies the acceptance criterion (P1), and increases as the first feature (x1) moves further away from the acceptance criterion (P1). As a result, the cost value is low when the first feature (x1) is close to the acceptance criterion (P1), and increases as it moves further away from the acceptance criterion (P1), allowing for appropriate evaluation of the coating film based on the cost value.

[0079] Furthermore, the maximum value (A) of the output of the second cost function (f2) coincides with the minimum value (A) of the output of the first cost function (f1). This avoids discontinuity between the range of cost values ​​output from the first cost function and the range of cost values ​​output from the second cost function. As a result, the output cost values ​​can be made continuous, allowing for appropriate evaluation of the coating film based on the cost values.

[0080] The first feature (x1) and the second feature (x2) include the variation range of the film thickness (R_s or R_e). This allows for appropriate evaluation of the uniformity of the film thickness of the coated film.

[0081] The first feature (x1) and the second feature (x2) include the difference (Diff_s or Diff_e) between a representative value (Th_s or Th_e) of the film thickness in the edge region (PS or PE) of the coated film and a representative value (Th_c) of the film thickness in the central region (PC) located inside the edge region (PS or PE). This allows for appropriate evaluation of the variation in film thickness in the edge region (PS or PE) relative to the film thickness in the central region (PC).

[0082] <2. Second Embodiment> Next, a second embodiment will be described. In the following description, elements having the same function as those already described will be given the same reference numeral or a reference numeral with an additional alphabetic character, and detailed descriptions may be omitted.

[0083] As explained in Figure 9, in the edge cut width setting step S2 of the first embodiment, two edge cut widths C1 and C2 are set, but in this embodiment, three edge cut widths are set. Specifically, in the edge cut width setting step S2, in addition to the edge cut widths C1 and C2, an edge cut width C3 (third edge cut width) is further set. The edge cut width C3 is a smaller value than the edge cut width C2 (i.e., C1 > C2 > C3). Then, in the feature calculation step S3 shown in Figure 9, in addition to the feature quantities x1 and x2, a feature quantity x3 corresponding to the edge cut width C3 is calculated from the acquired film thickness distribution TD.

[0084] Figure 10 shows an example of a cost function used when three edge cut widths C1, C2, and C3 are set. In this embodiment, in addition to cost functions f1 and f2, a cost function f3 is set. Cost function f3 is a function that takes feature x3 as input and outputs a cost value.

[0085] The cost function f1 in this embodiment is the same as the cost function f1 in the first embodiment. However, the output of the cost function f2 differs from the cost function f2 in that it takes the minimum value B when the feature x2 satisfies the passing criterion P2. That is, the cost function f2 in this embodiment is expressed by the following equation (3).

[0086]

number

[0087] The output of cost function f3 is smaller than the output of cost function f2. In this embodiment, the maximum value of the output of cost function f3 coincides with the minimum value B of the output of cost function f2. The output of cost function f3 takes the cost value C when feature x3 is at the passing threshold P3. The output of cost function f3 also takes the maximum value B when feature x3 is greater than or equal to the saturation feature s2. The saturation feature s2 is greater than the passing threshold P3. The cost function f3 increases monotonically with a positive slope c from zero to the saturation feature s2. That is, the cost function f3 is expressed by the following equation (4).

number

[0088] Even when three edge cut widths C1, C2, and C3 are set, the pass / fail status of feature x1 is determined in the judgment step S4, similar to the flow shown in Figure 9. If feature x1 fails (i.e., x1 > P1), the cost value is calculated using the cost function f1 (cost value calculation step S6). On the other hand, if feature x1 passes (x1 ≤ P1), the pass / fail status of feature x2 is determined. If feature x2 fails (x2 > P2), the cost value is calculated using the cost function f2, and if feature x2 passes (x2 ≤ P2), the cost value is calculated using the cost function f3. In other words, the cost value is calculated by inputting feature x3 into the cost function f3.

[0089] In this embodiment, the edge cut width C2 corresponds to the "first edge cut width," and the edge cut width C3 corresponds to the "second edge cut width." Also, feature x2 corresponds to the "first feature," and feature x3 corresponds to the "second feature." Furthermore, the cost function f2 corresponds to the "first cost function," and the cost function f3 corresponds to the "second cost function."

[0090] <3. Variant Example> Although embodiments have been described above, the present invention is not limited to those described above, and various modifications are possible.

[0091] For example, the feature quantities x1 and x2 may be indices other than the starting film thickness variation range R_s, the starting difference Diff_s, the ending film thickness variation range R_e, or the ending difference Diff_e.

[0092] Although this invention has been described in detail, the above description is illustrative in all respects, and the invention is not limited thereto. It is understood that countless variations not illustrated can be conceived without falling outside the scope of this invention. The components described in each of the above embodiments and variations can be combined or omitted as appropriate, as long as they do not contradict each other. [Explanation of Symbols]

[0093] 9: Control Unit (Coated Film Evaluation Device) 911: Film thickness distribution acquisition unit 913: Edge cut width setting section 915: Feature calculation unit 916: Judgment section 917: Cost value calculation unit 931: Computer program S: Circuit board TD: Film Thickness Distribution

Claims

1. A coating film evaluation method for evaluating a coating film applied to a substrate, a) A film thickness distribution acquisition step to acquire the film thickness distribution of the coating film formed on the substrate, b) An edge cut width setting step of setting a first edge cut width and a second edge cut width that are different from each other, which are the width dimensions of the region extending inward from the edge of the substrate, c) A determination step in which, with respect to the first characteristic quantity of the film thickness distribution excluding the film thickness in the region of the first edge cut width, a pass / fail step is made based on a pass / fail criterion value, d) If the product is determined to be unsatisfactory in step c), a first cost value calculation step is performed in which the first feature quantity is input into the first cost function to calculate the cost value, e) If the process is deemed acceptable in step c), a second cost value calculation step is performed, in which the second feature quantity of the film thickness distribution excluding the film thickness in the region of the second edge cut width is input into the second cost function to calculate the cost value, Includes, A coating film evaluation method wherein the output of the second cost function is less than or equal to the output of the first cost function.

2. A method for evaluating a coated film according to claim 1, A method for evaluating a coated film, wherein the first edge cut width is greater than the second edge cut width.

3. A method for evaluating a coating film according to claim 1 or claim 2, A coating film evaluation method wherein the output of the first cost function takes its minimum value when the first feature quantity satisfies the acceptance criteria value, and increases as the first feature quantity moves further away from the acceptance criteria value.

4. A method for evaluating a coating film according to claim 3, A coating film evaluation method wherein the maximum value of the output of the second cost function coincides with the minimum value of the output of the first cost function.

5. A method for evaluating a coating film according to claim 1 or claim 2, A method for evaluating a coated film, wherein the first and second feature quantities include the range of variation in film thickness.

6. A method for evaluating a coating film according to claim 1 or claim 2, A method for evaluating a coated film, wherein the first and second feature quantities include the difference between a representative value of the film thickness in the edge region of the coated film and a representative value of the film thickness in the central region inside the edge region.

7. A coating film evaluation apparatus for evaluating a coating film applied to a substrate, A film thickness distribution acquisition unit that acquires the film thickness distribution of a coated film formed on a substrate, An edge cut width setting unit sets a width dimension of the edge region extending inward from the edge of the substrate, and sets a first edge cut width and a second edge cut width that are different from each other. A feature calculation unit calculates a first feature quantity of the distribution obtained by excluding the film thickness in the edge region of the first edge cut width from the aforementioned film thickness distribution, and a second feature quantity of the distribution obtained by excluding the film thickness in the edge region of the second edge cut width. A determination unit that determines whether the first feature quantity of the first edge cut width is acceptable or unacceptable based on the acceptance criteria value, If the determination unit determines that it is unsuccessful, the cost value calculation unit inputs the first feature into the first cost function and calculates a cost value; if the determination unit determines that it is successful, the cost value calculation unit inputs the second feature into the second cost function and calculates a cost value; Equipped with, A coating film evaluation apparatus in which the output of the second cost function is less than or equal to the output of the first cost function.

8. It is a computer program, A computer program that causes a computer to perform the coating film evaluation method described in claim 1 or claim 2.

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