Tension measuring device and tension measuring method

Abstract

To provide a tension measuring device and a tension measuring method with which, even when a pellicle film is shaken by a factor other than spraying of gaseous matter, it is possible to accurately measure the tension of the pellicle film or the anisotropy of the tension in a contactless manner.SOLUTION: A tension measuring device comprises: an air nozzle for spraying compressed air to a pellicle film; first ultrasonic sensors 232, 233, 234, 235 for measuring the displacement of the pellicle film in the orthogonal direction due to the sprayed compressed air; second ultrasonic sensors 332, 333, 334, 335 for measuring the displacement of the pellicle film in the orthogonal direction outside a region on the pellicle film where the displacement due to the sprayed compressed air occurs; and a control unit for measuring the tension acting upon the pellicle film, on the basis of the difference between the displacement of the pellicle film measured by the first ultrasonic sensors 232, 233, 234, 235 and the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, 335.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a tension measurement device and a tension measurement method for measuring the tension of a stretched film such as a pellicle film. [Background technology]

[0002] In a photography process for manufacturing devices such as semiconductor elements and liquid crystal display elements, an image of a circuit pattern formed on a mask is transferred onto a resist layer on a photosensitive substrate via the optical system of an exposure device.

[0003] In general, in order to prevent foreign matter such as dust from adhering to the pattern area of ​​a mask, a pellicle film is stretched over a pellicle frame disposed surrounding the pattern area so as to cover the pattern area.

[0004] The pellicle film must be stretched over the pellicle frame with a predetermined tension, and it is desirable that the tension be equal in both the vertical and horizontal directions.

[0005] The pellicle membrane is attached to a rectangular pellicle frame. During attachment, the pellicle is attached to the frame while being pulled in directions parallel to the long and short sides of the frame (vertical and horizontal directions).

[0006] At this time, it is desirable that the tension in the longitudinal and transverse directions be equal, and it is necessary to measure the anisotropy, which is the difference between the tension in the longitudinal and transverse directions.

[0007] Furthermore, since the pellicle membrane is an extremely thin membrane on the order of microns, it is impossible to measure the tension by contact, and it is necessary to measure the tension without contact.

[0008] A conventional tension measurement device known for non-contact measurement of pellicle film tension and tension anisotropy is the tension measurement device described in Patent Document 1. This tension measurement device measures the pellicle film tension and tension anisotropy in a non-contact manner by injecting compressed air at the pellicle film and detecting the resulting changes in the pellicle film using four ultrasonic sensors. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent Publication No. 2021-179592 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the tension measuring device described in Patent Document 1, if the pellicle film vibrates due to factors other than compressed air when measuring the tension or tension anisotropy of the pellicle film, there is a risk that the tension or tension anisotropy of the pellicle film may not be measured accurately.

[0011] For example, in clean rooms where pellicle film tension measurement devices are installed, the downflow method is mainly used for air conditioning and airflow, and the downflow can cause the pellicle film to vibrate. If the pellicle film vibrates due to the influence of the downflow, it will be impossible to accurately measure the pellicle film tension and tension anisotropy.

[0012] Here, if the amplitude of the vibration of the pellicle film caused by the injection of compressed air from the tension measurement device is sufficiently larger than the vibration of the pellicle film caused by the downflow, the above-mentioned problem will not occur. However, if the pellicle film is injected with compressed air strong enough to avoid the above-mentioned problem, the pellicle film will undergo plastic deformation or destruction. For this reason, in reality, measurements can only be performed under conditions where the amplitude of the vibration of the pellicle film caused by the downflow is equal to or larger than the amplitude of the vibration of the pellicle film caused by the injection of compressed air from the tension measurement device. Under these constraints, a measurement device and measurement method capable of measuring the tension of the pellicle film are needed.

[0013] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a tension measurement device and a tension measurement method that can accurately measure the tension and tension anisotropy of a pellicle film without contact, even when the pellicle film vibrates due to factors other than gas injection. [Means for solving the problem]

[0014] The tension measuring device of the present invention comprises a nozzle that injects gas onto a pellicle film under a predetermined tension; at least one first ultrasonic sensor arranged concentrically around the nozzle on a line passing through the center of the nozzle parallel to the tension direction in which the pellicle film is subjected to the tension, the first ultrasonic sensor measuring the displacement of the pellicle film in an orthogonal direction perpendicular to the tension direction caused by the gas injected from the nozzle; a plurality of second ultrasonic sensors that measure the displacement of the pellicle film in the orthogonal direction on the pellicle film outside the area where displacement occurs due to the gas injected from the nozzle; and a control unit that measures the tension applied to the pellicle film based on the difference between the displacement of the pellicle film measured by the first ultrasonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor.

[0015] With this configuration, the tension measurement device of the present invention measures the displacement of the pellicle film in a direction perpendicular to the tension direction caused by the gas injected from the nozzle using the first ultrasonic sensor, thereby measuring the tension applied to the pellicle film.As a result, it is possible to measure the tension and tension anisotropy of the pellicle film in a non-contact manner.

[0016] In addition, the tension measuring device of the present invention is configured to provide a plurality of second ultrasonic sensors on the pellicle film to measure the displacement of the pellicle film in a perpendicular direction outside the area where displacement occurs due to the gas sprayed from the nozzle, and to measure the tension applied to the pellicle film based on the difference between the displacement of the pellicle film measured by the first ultrasonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor.

[0017] As a result, even if the pellicle membrane vibrates due to factors other than the gas jet, such as a downflow in a clean room, the tension measurement device of the present invention can eliminate the influence of displacement of the pellicle membrane caused by factors other than the gas jet and can accurately measure the displacement of the pellicle membrane due to the gas jet. As a result, the tension and tension anisotropy of the pellicle membrane can be accurately measured without contact.

[0018] In addition, in the tension measurement device of the present invention, the first ultrasonic sensor is configured to have two sensors arranged concentrically around the nozzle, on a line that is parallel to the tension direction and passes through the center of the nozzle, with the nozzle in between.

[0019] With this configuration, the tension measuring device of the present invention can measure changes in the pellicle film on both sides of the position where gas is injected in the direction of tension in which the pellicle film is under tension, and can accurately measure the tension and tension anisotropy of the pellicle film.

[0020] In the tension measuring device of the present invention, the control unit has a configuration for injecting the gas at a predetermined minute pressure in pulses onto the pellicle film.

[0021] With this configuration, the tension measuring device of the present invention can accurately measure the tension and tension anisotropy of the pellicle film without damaging the pellicle film and while minimizing the effect on sound waves.

[0022] In addition, in the tension measuring device of the present invention, the control unit measures the time it takes for the pellicle membrane to return to half of the maximum amount of change from the time it is displaced to its maximum after the gas is injected as a half-return time, and is configured to measure the tension applied to the pellicle membrane based on the half-return time.

[0023] With this configuration, the tension measurement device of the present invention can suppress the influence of fluctuations in gas injection pressure and measure the tension of the pellicle film with high accuracy.

[0024] In addition, in the tension measuring device of the present invention, the pellicle film is subjected to the tension in multiple directions, and at least one first ultrasonic sensor is provided in each of the multiple directions on a line parallel to the tension direction and passing through the center of the nozzle, and the control unit is configured to measure the maximum change amount when the pellicle film is displaced to its maximum after the gas is injected, and measure the anisotropy of the multiple tensions acting on the pellicle film based on the maximum change amount.

[0025] With this configuration, the tension measurement device of the present invention can suppress the mutual influence of the directions in which tension is applied and accurately measure the anisotropy of multiple tensions in the pellicle film.

[0026] In addition, the tension measuring device of the present invention is further provided with a reflecting unit that reflects ultrasonic waves in the vicinity of the nozzle, and the first ultrasonic sensor is configured to be positioned farther away from the nozzle than the reflecting unit.

[0027] With this configuration, the tension measurement device of the present invention can reduce the distance between the center of the nozzle and the center line that passes through the center of the first ultrasonic sensor and is perpendicular to the transmitting and receiving surface of the first ultrasonic sensor. This allows the first ultrasonic sensor to measure deformation of the pellicle film that is close to the center of the nozzle and that allows accurate measurement of the anisotropy of the tension. This makes it possible to measure a deformation amount that allows accurate measurement of the anisotropy of the pellicle film tension.

[0028] Furthermore, the tension measuring device of the present invention further includes an inclined member, located on the straight line between the first ultrasonic sensor and the center of the nozzle, having an inclined surface inclined with respect to the ejection direction of the gas ejected from the nozzle, wherein the reflecting portion is formed by the inclined surface, and the first ultrasonic sensor is configured so that its receiving surface faces the inclined surface so as to be able to receive ultrasonic waves reflected by the inclined surface.

[0029] With this configuration, the tension measuring device of the present invention reflects ultrasonic waves by the inclined surface of the inclined member, so that even if the first ultrasonic sensor is placed at a position away from the nozzle, it can measure the deformation of the pellicle film using the first ultrasonic sensor, which is close to a position facing the center of the nozzle and can accurately measure the anisotropy of tension.

[0030] Moreover, the tension measuring device of the present invention further includes a support member that supports the first ultrasonic sensor, and the support member is configured to be able to adjust the angle of the first ultrasonic sensor with respect to the reflecting portion.

[0031] With this configuration, the tension measurement device of the present invention can adjust the position on the pellicle membrane where the ultrasonic waves hit, thereby adjusting the position at which the first ultrasonic sensor measures the deformation of the pellicle membrane.

[0032] In the tension measuring device of the present invention, the inclined member has a hollow portion that accommodates the nozzle.

[0033] With this configuration, the tension measurement device of the present invention can prevent interference between the gas ejected from the nozzle and the ultrasonic waves, thereby preventing the ultrasonic waves received by the first ultrasonic sensor from being affected by the gas ejected from the nozzle.

[0034] Furthermore, the tension measuring device of the present invention has a configuration in which the first ultrasonic sensor and the second ultrasonic sensor are arranged so that the length of the ultrasonic wave propagation path of the first ultrasonic sensor and the length of the ultrasonic wave propagation path of the second ultrasonic sensor are the same.

[0035] With this configuration, the tension measuring device of the present invention does not need to make corrections due to differences in the length of the ultrasonic wave propagation path of the first ultrasonic sensor and the length of the ultrasonic wave propagation path of the second ultrasonic sensor, thereby simplifying the processing by the control unit.

[0036] In addition, in the tension measuring device of the present invention, four of the first ultrasonic sensors are arranged on a concentric circle centered on the nozzle, four of the second ultrasonic sensors are arranged on a concentric circle different from the first ultrasonic sensors centered on the nozzle, the first ultrasonic sensors and the second ultrasonic sensors are arranged alternately in a circumferential direction centered on the nozzle, and the control unit is configured to, when calculating the difference between the displacement of the pellicle film measured by one first ultrasonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor, weight each of the displacements of the pellicle film measured by the four second ultrasonic sensors according to their distance from the one first ultrasonic sensor, calculate a weighted average of the weighted displacements of the pellicle film, and regard the weighted average as the displacement of the pellicle film measured by the second ultrasonic sensor.

[0037] With this configuration, the tension measurement device of the present invention can more accurately measure the displacement of the pellicle film caused by, for example, a downflow, which may vary depending on the placement of the first ultrasonic sensors. As a result, each of the first ultrasonic sensors can more accurately measure the displacement of the pellicle film caused by the gas injected from the nozzle.

[0038] In addition, the tension measurement method of the present invention comprises the steps of injecting gas from a nozzle onto a pellicle film under a predetermined tension; measuring the displacement of the pellicle film in an orthogonal direction perpendicular to the tension direction, in which the pellicle film is subjected to the tension, caused by the gas injected from the nozzle, using at least one first ultrasonic sensor arranged concentrically around the nozzle and on a line parallel to the tension direction and passing through the center of the nozzle; measuring the displacement of the pellicle film in the orthogonal direction on the pellicle film outside the area where displacement occurs due to the gas injected from the nozzle using a plurality of second ultrasonic sensors; and measuring the tension applied to the pellicle film based on the difference between the displacement of the pellicle film measured by the first ultrasonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor.

[0039] According to the tension measurement method of the present invention, the displacement of the pellicle film in a direction perpendicular to the tension direction caused by the gas injected from the nozzle is measured by the first ultrasonic sensor, and the tension applied to the pellicle film is measured. Therefore, the tension and tension anisotropy of the pellicle film can be measured in a non-contact manner.

[0040] Furthermore, the tension applied to the pellicle film is measured based on the difference between the displacement of the pellicle film measured by the first ultrasonic sensor and the displacement of the pellicle film measured by a plurality of second ultrasonic sensors that measure the displacement of the pellicle film in the orthogonal direction outside the area on the pellicle film where displacement occurs due to the gas injected from the nozzle. This allows the influence of the displacement of the pellicle film caused by factors other than the gas injection to be eliminated, even if the pellicle film vibrates due to factors other than the gas injection, such as a downflow in a clean room, and the displacement of the pellicle film due to the gas injection can be accurately measured. As a result, the tension of the pellicle film and the anisotropy of the tension can be accurately measured without contact. [Effects of the Invention]

[0041] The present invention provides a tension measurement device and a tension measurement method that can accurately measure the tension and tension anisotropy of a pellicle film without contact, even when the pellicle film vibrates due to factors other than gas injection. [Brief explanation of the drawings]

[0042] [Figure 1] FIG. 1 is a front view of a pellicle inspection device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a plan view of a pellicle inspection apparatus according to an embodiment of the present invention. [Figure 3] FIG. 3 is a block diagram of a tension measurement device according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing an example of a change in a pellicle film measured by a tension measurement device according to an embodiment of the present invention. [Figure 5] Figure 5 shows a modified example of a pellicle film measured by a tension measurement device according to one embodiment of the present invention, where Figure 5(a) shows an example in which the tension on the top, bottom, left and right sides is equal, and Figure 5(b) shows an example in which the tension on the left and right sides is greater. [Figure 6] FIG. 6 is a perspective view of a tension measuring device according to one embodiment of the present invention. [Figure 7] FIG. 7 is a side view of a tension measurement device according to one embodiment of the present invention. [Figure 8] FIG. 8 is a side cross-sectional view taken along the center of the air nozzle of a tension measurement device according to one embodiment of the present invention. [Figure 9] FIG. 9 is a side view showing the distance between the center of the air nozzle and the center of each ultrasonic sensor in a tension measurement device according to one embodiment of the present invention. [Figure 10] FIG. 10 is a graph showing the change over time in the amount of deformation of the pellicle film when tension is measured by the tension measurement device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] Hereinafter, a pellicle inspection apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

[0044] 1, the direction perpendicular to the paper surface is the X direction, the vertical direction of the paper surface is the Y direction, and the direction perpendicular to the X and Y directions is the Z direction. Note that some components are not shown in FIG.

[0045] [Pellicle inspection equipment] In Figure 1, a pellicle inspection device 1 according to one embodiment of the present invention is an inspection device that supports, for example, a rectangular pellicle frame P on which a pellicle film to be inspected is stretched in an approximately vertical direction, and inspects the pellicle film stretched on the pellicle frame P by moving a camera or the like in the vertical direction.

[0046] 1 and 2, the pellicle inspection device 1 includes a surface plate 10, an inspection unit 20, a pellicle support unit 30, and a vibration isolation table 50.

[0047] The surface plate 10 is configured as a stage, and is supported on vibration isolation tables 50 installed at multiple locations (six locations) on the installation surface F.

[0048] The surface plate 10 has a lower surface 10a and an upper surface 10e parallel to the lower surface 10a, and the distance between the lower surface 10a and the upper surface 10e is shorter than the short side of the upper surface 10e.

[0049] Approximately cubic recesses 10b and 10c are formed on the lower surface 10a of the base plate 10. Recesses 10b are formed at each of the four corners of the lower surface 10a. Recesses 10c are formed at two locations, one along each long side of the lower surface 10a. In this way, recesses 10b and recesses 10c are formed in a total of six locations. By providing recesses 10c in addition to recesses 10b, distortion of the base plate 10 can be reduced.

[0050] Inside the recesses 10b and 10c, a vibration isolation table 50 is provided, which is placed on a mounting surface F. The bottom surfaces of the recesses 10b and 10c are support surfaces 10d that are supported by the vibration isolation table 50.

[0051] 1, the height of the vibration isolation table 50 is greater than the depth of the recesses 10b and 10c. Therefore, the vibration isolation table 50 supports the support surface 10d, and the surface plate 10 is placed on the installation surface F via the vibration isolation table 50.

[0052] Grooves 10f are formed in the upper surface 10e of the surface plate 10. The grooves 10f are formed along the longitudinal direction (X direction) of the surface plate 10 at positions that do not overlap with the recesses 10b and 10c in a plan view (see FIG. 2).

[0053] The depth of the grooves 10f is sufficiently smaller than the thickness of the surface plate 10. Therefore, even if the grooves 10f are formed, the rigidity of the surface plate 10 can be kept sufficiently high.

[0054] Groove 10f supports pellicle support part 30 so that it can move freely in the X direction. By using groove 10f as a guide when moving pellicle support part 30, the height of inspection part 20 and pellicle support part 30 can be lowered, thereby lowering the center of gravity.

[0055] The depth of groove 10f is set so that the optical axis of camera 22 when tension measuring device 23 abuts against upper surface 10e of base plate 10 coincides with the lower end of pellicle frame P supported by pellicle support portion 30. In other words, camera 22 and tension measuring device 23 can inspect the entire surface of pellicle frame P supported by pellicle support portion 30.

[0056] The inspection section 20 is composed of a pillar 21 protruding upward from the base plate 10, a camera 22 and a tension measuring device 23 mounted on the pillar 21, and a support section 24 that supports the pellicle support section 30 at the inspection position.

[0057] The pillars 21 are attached to the upper surface 10e of the surface plate 10 so as to protrude upward (in the +Y direction) from the upper surface 10e. The pillars 21 are made of ceramic or the like. In order to lower the center of gravity, the pillars 21 are preferably hollow.

[0058] The camera 22 is configured, for example, by a CCD (Charge-Coupled Device) camera or a TDI (Time Delay Integration) camera, which is a special CCD camera.

[0059] The tension measuring device 23 measures the tension of the pellicle film stretched across the pellicle frame P.

[0060] A moving unit (not shown) including an air pad is provided between the camera 22 and the tension measuring device 23. The camera 22 is provided on the moving unit so that its optical axis is parallel to the Z axis.

[0061] The movement of the moving unit in the vertical direction (Y direction) causes the camera 22 and tension measurement device 23 to move in the vertical direction. The moving unit moves the camera 22 and tension measurement device 23 along the pillar 21 between an initial position where the tension measurement device 23 abuts against the upper surface 10e of the base plate 10 and an upper end position (the position indicated by the two-dot chain line in FIG. 1) where the camera 22 is located near the upper end of the pillar 21.

[0062] The support portion 24 supports the pellicle support portion 30 so that the pellicle support portion 30 does not tilt in the horizontal direction when the pellicle support portion 30 is moved to the inspection position.

[0063] The pellicle support part 30 supports the pellicle frame P. The pellicle support part 30 includes a frame 31, an adjustment mechanism 32, and a guide member 33.

[0064] Frame 31 is formed in a frame shape so as to surround the outer periphery of a vertically supported pellicle frame P. Frame 31 supports pellicle frame P so that the pellicle film of pellicle frame P is parallel to the XY plane.

[0065] An adjustment mechanism 32 is provided below the frame 31. The adjustment mechanism 32 changes the position in the height direction (Y direction) of the lower side of the pellicle frame P. The guide member 33 is a member that moves inside the groove 10f.

[0066] [Major components of tension measurement device] Next, the tension measuring device 23 will be described. As shown in FIG. 3, the tension measuring device 23 mainly comprises an air nozzle 231 as a nozzle, a first ultrasonic sensor 232, a first ultrasonic sensor 233, a first ultrasonic sensor 234, a first ultrasonic sensor 235, a second ultrasonic sensor 332, a second ultrasonic sensor 333, a second ultrasonic sensor 334, a second ultrasonic sensor 335, a compressed air injection unit 236, and a control unit 237.

[0067] (Air nozzle) The air nozzle 231 injects air (gas) compressed by the compressed air injection unit 236 onto the pellicle film. The tension measurement device 23 is provided on the moving part so that the air injected from the air nozzle 231 hits the pellicle film approximately perpendicularly.

[0068] (First ultrasonic sensor) The first ultrasonic sensors 232, 233, 234, and 235 emit ultrasonic waves and receive the ultrasonic waves reflected from an object to measure the distance to the object.

[0069] As shown in Fig. 6, the first ultrasonic sensor 232 is provided above the air nozzle 231 (see Fig. 8). The first ultrasonic sensor 233 is provided below the air nozzle 231 (see Fig. 8). The first ultrasonic sensor 234 is provided to the right of the air nozzle 231 (see Fig. 8). The first ultrasonic sensor 235 is provided to the left of the air nozzle 231 (see Fig. 8).

[0070] The first ultrasonic sensors 232, 233, 234, and 235 are provided on a plane parallel to the pellicle film, concentrically arranged in the up, down, left, and right directions with the air nozzle 231 at the center.

[0071] The first ultrasonic sensor 232 and the first ultrasonic sensor 233 are provided so that their centers are located on the same straight line in the up-down direction (Y direction). The first ultrasonic sensor 234 and the first ultrasonic sensor 235 are provided so that their centers are located on the same straight line in the left-right direction (X direction).

[0072] The first ultrasonic sensors 232, 233, 234, and 235 are preferably installed on either side of the air nozzle 231 in the direction in which the pellicle film stretched across the pellicle frame P is subjected to tension (hereinafter referred to as the "tension direction"). In this embodiment, since the pellicle frame P is rectangular, the pellicle film is subjected to tension in two directions: up and down and left and right. For this reason, the first ultrasonic sensors 232, 233, 234, and 235 are installed in the four directions: up, down, left, and right.

[0073] The first ultrasonic sensors 232, 233, 234, and 235 are configured to measure the displacement of the pellicle film caused by the air jetted from the air nozzle 231 in a direction perpendicular to the above-mentioned tension direction (hereinafter referred to as the "perpendicular direction").

[0074] (Second ultrasonic sensor) Like the first ultrasonic sensor, the second ultrasonic sensors 332, 333, 334, and 335 emit ultrasonic waves and receive the ultrasonic waves reflected from an object to measure the distance to the object.

[0075] 6, the second ultrasonic sensor 332 is provided to the right of the first ultrasonic sensor 232 and above the first ultrasonic sensor 234. The second ultrasonic sensor 333 is provided to the left of the first ultrasonic sensor 232 and above the first ultrasonic sensor 235. The second ultrasonic sensor 334 is provided to the left of the first ultrasonic sensor 233 and below the first ultrasonic sensor 235. The second ultrasonic sensor 335 is provided to the right of the first ultrasonic sensor 233 and below the first ultrasonic sensor 234.

[0076] The second ultrasonic sensors 332, 333, 334, and 335 are provided on a concentric circle different from the first ultrasonic sensors 232, 233, 234, and 235, with the air nozzle 231 at the center.

[0077] The first ultrasonic sensors 232, 233, 234, and 235 and the second ultrasonic sensors 332, 333, 334, and 335 are arranged alternately in the circumferential direction around the air nozzle 231.

[0078] The second ultrasonic sensors 332, 333, 334, and 335 are configured to measure the displacement of the pellicle film in the orthogonal direction described above outside the region (the region indicated by R in FIG. 9) on the pellicle film where displacement occurs due to air sprayed from the air nozzle 231. The second ultrasonic sensors 332, 333, 334, and 335 measure the displacement of the pellicle film due to, for example, a downflow in a clean room.

[0079] The second ultrasonic sensors 332, 333, 334, and 335 are capable of measuring outside the area where displacement occurs due to the air sprayed from the air nozzle 231 (the area indicated by R in Figure 9), and more preferably are configured to measure the displacement of the pellicle membrane at a position close to the area R where displacement occurs due to the air sprayed from the air nozzle 231.

[0080] (Compressed air injection part) As shown in FIG. 3, the compressed air injection unit 236 is composed of a compressor, a solenoid valve, etc., and compresses air and injects it at a predetermined pressure through the air nozzle 231 onto the pellicle film stretched on the pellicle frame P.

[0081] (Control unit) The control unit 237 controls the first ultrasonic sensors 232 , 233 , 234 , and 235 , the second ultrasonic sensors 332 , 333 , 334 , and 335 , and the compressed air injection unit 236 .

[0082] The control unit 237 injects air from the compressed air injection unit 236 from the air nozzle 231 onto the pellicle membrane stretched on the pellicle frame P at a predetermined pressure for a predetermined period of time, and measures the amount of depression of the pellicle membrane that has received the air using the first ultrasonic sensors 232, 233, 234, and 235.

[0083] The control unit 237 injects compressed air at a predetermined minute pressure in pulses onto the pellicle membrane. For example, the control unit 237 injects compressed air at a minute pressure that does not damage the pellicle membrane in pulses onto the pellicle membrane. Not damaging the pellicle membrane means not causing plastic deformation in the pellicle membrane. For example, this means that the tension applied to the pellicle membrane is not weakened.

[0084] At the moment the compressed air is injected, the adiabatically expanded air spreads out at the tip of the air nozzle 231, changing the temperature and affecting the speed of sound. However, by injecting it in pulses, the expanded air does not directly reach the pellicle membrane or ultrasonic path, but simply pushes against the air that was there before, so the cold air does not disrupt the measurement.

[0085] On the other hand, since there is air behind the pellicle membrane in the direction of compressed air injection, it is difficult for the membrane to deform with pulsed injection regardless of the tension of the pellicle membrane, so the injection pressure is set to a value suitable for measurement.

[0086] FIG. 4 is a graph showing an example of the amount of deformation of the pellicle membrane after the start of compressed air injection (blowing start).

[0087] 4 are likely to be affected by fluctuations in the compressed air injection pressure, and it is necessary to consider the stability of the solenoid valve of the compressed air injection unit 236. In contrast, for example, the time it takes to return halfway ("half return time" in the figure) is thought to change little due to the compressed air injection pressure.

[0088] For this reason, the control unit 237 of this embodiment measures the time it takes for the pellicle membrane to return to half of the maximum change from the time it changes most after compressed air is injected as the half-return time, and measures the tension of the pellicle membrane based on this half-return time.

[0089] The area of ​​the pellicle membrane that is deformed by a pinpoint injection of compressed air is limited to a diameter of about 50 mm, which is measured by the first ultrasonic sensors 232, 233, 234, and 235, each having a diameter of 10 mm, for example.

[0090] The control unit 237 measures, for example, the half return time within a diameter of 10 mm using the first ultrasonic sensors 232, 233, 234, and 235, calculates the average value of the measured half return times, and calculates the tension of the pellicle film from the calculated average value.

[0091] The half return time may be calculated by averaging the measurement values ​​of the ultrasonic sensors aligned in the direction in which tension is applied (first ultrasonic sensor 232 and first ultrasonic sensor 233, and first ultrasonic sensor 234 and first ultrasonic sensor 235).

[0092] In addition, the strength of the tension may be determined using the maximum change amount or return speed of the pellicle film rather than the half return time of the pellicle film when compressed air is injected.

[0093] On the other hand, if you try to measure the anisotropy of tension, for example, by measuring the ratio of vertical to horizontal tension, the vertical tension will affect the horizontal direction, and the horizontal tension will affect the vertical direction, making it inappropriate to measure it using the half-return time.

[0094] Therefore, the control unit 237 measures the anisotropy of the tension based on the magnitude of the change at the time when the pellicle film changes to the maximum after the compressed air is injected.

[0095] Figure 5 shows a line connecting points with equal amounts of change when the pellicle film changes the most after compressed air is injected (when the part corresponding to the air nozzle 231 from which compressed air is injected is pushed in the most).

[0096] As shown in FIG. 5(a), if the figure connecting the points where the amount of change is the same is close to a circle, that is, if the amount of change measured by the first ultrasonic sensors 232, 233, 234, and 235 is approximately equal, the tension in the up, down, left, and right directions is uniform.

[0097] As shown in Figure 5(b), if the figure connecting the points where the amount of change is the same becomes an ellipse, the tension in the vertical and horizontal directions is not uniform.

[0098] The control unit 237, for example, averages the measurement values ​​of the ultrasonic sensors (first ultrasonic sensor 232 and first ultrasonic sensor 233, first ultrasonic sensor 234 and first ultrasonic sensor 235) aligned in the direction of tension for the maximum pellicle deformation amounts measured by the first ultrasonic sensors 232, 233, 234, and 235. If the difference in the average values ​​of the maximum pellicle deformation amounts for each direction of tension is within a predetermined range, the control unit 237 determines that the tension in each direction of tension is approximately uniform.

[0099] The control unit 237, for example, jets compressed air in pulses, performs measurement with one of the first ultrasonic sensors 232, 233, 234, 235 with each jet, and performs measurements up, down, left, and right with four measurements.

[0100] The distance between the pellicle film and the first ultrasonic sensors 232, 233, 234, and 235, i.e., half the length of the ultrasonic propagation path of the first ultrasonic sensors 232, 233, 234, and 235, is preferably, for example, about 50 mm, but in this embodiment, the distance to the pellicle film is adjusted using a moving unit during measurement. Here, the ultrasonic propagation path refers to, for example, the path along which ultrasonic waves transmitted from the sensor vibration surface of the ultrasonic sensor are reflected by the pellicle film and received again by the ultrasonic sensor.

[0101] The control unit 237 measures the amount of deformation of the pellicle film caused by, for example, a downflow in the clean room using the second ultrasonic sensors 332, 333, 334, and 335. Outside the area where displacement occurs due to the air sprayed from the air nozzle 231, the pellicle film may be displaced in one orthogonal direction (for example, a direction away from the tension measurement device 23) or the other (for example, a direction approaching the tension measurement device 23) due to the influence of the downflow or the like.

[0102] For example, the control unit 237 measures the displacement of the pellicle film in one of the orthogonal directions as a positive value, and measures the displacement of the pellicle film in the other orthogonal direction as a negative value.

[0103] The control unit 237 is configured to measure the tension applied to the pellicle film based on the difference between the displacement of the pellicle film measured by the first ultrasonic sensors 232, 233, 234, and 235 and the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335.

[0104] Specifically, the control unit 237 subtracts the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335 from the displacement of the pellicle film measured by the first ultrasonic sensors 232, 233, 234, and 235, thereby eliminating the influence of displacement of the pellicle film caused by, for example, downflow within a clean room, and making it possible to measure only the displacement of the pellicle film caused by the air sprayed from the air nozzle 231.

[0105] [Specific configuration of tension measurement device] Next, a specific configuration of the tension measuring device 23 will be described with reference to FIGS.

[0106] As shown in Figures 6 to 8, the tension measurement device 23 includes a support base 240, a support column 241, and a device main body 242. The support base 240 is attached to a moving part (not shown) provided on the column 21 (see Figure 1). The lower end of the support column 241 is fixed to the upper surface of the support base 240. The device main body 242 is fixed to the upper end of the support column 241. In Figures 6 to 8, the surface of the tension measurement device 23 facing the pellicle film is defined as the front surface, and the surface opposite to the front surface is defined as the back surface.

[0107] The tension measuring device 23 is configured to be movable up and down along the pillar 21 by having the support base 240 attached to a moving part (not shown) provided on the pillar 21 (see FIG. 1).

[0108] The tension measuring device 23 may be configured without the support base 240 and the support pillar 241. In this case, the tension measuring device 23 has a device main body 242 attached to a moving part (not shown) provided on the pillar 21 (see FIG. 1).

[0109] As shown in FIGS. 6 and 7, the device body 242 is provided with support members 245 that support the first ultrasonic sensors 232, 233, 234, and 235, respectively.

[0110] (support member) Each of the first ultrasonic sensors 232, 233, 234, 235 is supported by a corresponding support member 245, and is disposed at a position farther away from the air nozzle 231 (see FIG. 8) than an inclined surface 242a of the device body 242, which will be described later.

[0111] Each support member 245 includes a sensor housing 245a that holds the first ultrasonic sensors 232, 233, 234, and 235, respectively, and a bracket 245b that rotatably supports the sensor housing 245a.

[0112] 8, each of the first ultrasonic sensors 232, 233, 234, and 235 is held in the sensor housing 245a by two O-rings 250. The two O-rings 250 are spaced apart from each other in a direction perpendicular to the transmitting / receiving surface S of each of the first ultrasonic sensors 232, 233, 234, and 235 and are wound around the outer periphery of each of the first ultrasonic sensors 232, 233, 234, and 235. This makes it possible to prevent vibrations transmitted from the first ultrasonic sensors 232, 233, 234, and 235 to the sensor housing 245a from being transmitted to other members (for example, metal parts).

[0113] The sensor housing 245a is supported by the bracket 245b so that it can rotate relative to the bracket 245b in the direction indicated by the arrow P in the figure (hereinafter referred to as the "pitch direction") around the shaft member 245c as a fulcrum, i.e., so that the angle between the transmitting / receiving surface S of the ultrasonic sensor and the inclined surface 242a described later can be adjusted.

[0114] The shaft member 245c functions as a rotation shaft of the sensor housing 245a and also as a fixing member that fixes the sensor housing 245a at an adjusted angle so that it cannot rotate.

[0115] 7, bracket 245b is supported by device body 242 so as to be rotatable about shaft member 245d as a fulcrum in the direction indicated by arrow Y in the drawing (hereinafter referred to as the "yaw direction") relative to device body 242, that is, so as to be adjustable in the rotation angle on the installation plane of bracket 245b on device body 242. This makes it possible to adjust the rotation angle of sensor housing 245a in the yaw direction.

[0116] The bracket 245b is fixed by two fixing members 245e so as not to be rotatable relative to the device body 242 at an adjusted rotation angle.

[0117] Note that the support member 245 is not limited to the above-described configuration as long as it is capable of adjusting the rotation angles of the sensor housing 245a in the pitch direction and yaw direction. Furthermore, the support member 245 may be configured to be capable of adjusting the rotation angle of the sensor housing 245a in either the pitch direction or the yaw direction.

[0118] (slanted surface) As shown in Fig. 8, device body 242 has inclined surfaces 242a formed on the front side (left side in Fig. 8). The inclined surfaces 242a are formed on the top, bottom, left and right sides in accordance with first ultrasonic sensors 232, 233, 234, 235. Device body 242 according to this embodiment constitutes an inclined member.

[0119] Each inclined surface 242a is inclined so as to gradually approach the center On (indicated by the dashed line in FIG. 8) of the air nozzle 231 from the rear side toward the front tip of the device body 242. Therefore, the shape of the front side of the device body 242 is a truncated quadrangular pyramid with the front tip of the device body 242 as the upper surface, or a quadrangular pyramid with the front tip of the device body 242 as the apex.

[0120] Each inclined surface 242a is arranged on a straight line passing through the center On of the air nozzle 231, parallel to the tension direction in which the pellicle film is subjected to tension concentrically around the air nozzle 231, and is located between each of the first ultrasonic sensors 232, 233, 234, 235 and the center On of the air nozzle 231.

[0121] Each inclined surface 242a functions as a reflecting portion that reflects ultrasonic waves (transmitted waves) output from the first ultrasonic sensors 232, 233, 234, 235 in the vicinity of the air nozzle 231, and ultrasonic waves (reflected waves) reflected by the pellicle film.

[0122] In this embodiment, the inclined surface 242a is formed on the device body 242, but the inclined surface 242a may be formed on a member separate from the device body 242.

[0123] Each of the first ultrasonic sensors 232, 233, 234, and 235 is installed with its transmitting / receiving surface S facing the corresponding inclined surface 242a so as to be able to receive ultrasonic waves reflected by the corresponding inclined surface 242a.

[0124] (hollow part) As shown in FIG. 8, the device body 242 has a hollow portion 242b that houses the air nozzle 231.

[0125] Hollow portion 242b is a cylindrical hollow space formed so as to penetrate device body 242 from the front end to the rear side, and is formed so as to surround air nozzle 231. The shape of hollow portion 242b is not limited to a cylindrical shape, and may be a polygonal cylindrical shape.

[0126] The open end (left end in FIG. 8) on the front side of the hollow portion 242b is preferably located closer to the front side than the tip of the air nozzle 231 on the front side.

[0127] (frame member) 6, the tension measuring device 23 has a frame member 300 provided to surround the device main body 242. The frame member 300 is attached to a moving part (not shown) provided on the pillar 21 (see FIG. 1).

[0128] Sensor housings 340 that hold second ultrasonic sensors 332, 333, 334, and 335 are attached to the inside of the four corners of frame member 300. Here, the lengths of the four sides of frame member 300 and the like are set so that second ultrasonic sensors 332, 333, 334, and 335 are outside region R (see FIG. 9), and more preferably, are positioned so that they can measure displacement of the pellicle film at positions close to region R where displacement occurs due to air sprayed from air nozzle 231.

[0129] Like the first ultrasonic sensors 232, 233, 234, and 235, each of the second ultrasonic sensors 332, 333, 334, and 335 is preferably held in the corresponding sensor housing 340 via two O-rings (not shown).

[0130] The sensor housing 340 of the second ultrasonic sensors 333 and 334 has a surface 340a that slopes toward the rear as it moves leftward in Fig. 7. The sensor housing 340 of the second ultrasonic sensors 332 and 335 has a surface 340a that slopes toward the rear as it moves rightward in Fig. 7.

[0131] As a result, of the ultrasonic waves output from each of the second ultrasonic sensors 332, 333, 334, and 335 and reflected by the pellicle film, those other than those returning to the second ultrasonic sensors 332, 333, 334, and 335 are reflected by the inclined surface 340a of the sensor housing 340 toward the outside of the frame member 300 (outward to the left and right in this embodiment). For this reason, of the ultrasonic waves reflected by the pellicle film, those other than those returning to the second ultrasonic sensors 332, 333, 334, and 335 do not interfere with the ultrasonic waves returning to the second ultrasonic sensors 332, 333, 334, and 335 or the first ultrasonic sensors 232, 233, 234, and 235 due to multiple reflections between the sensor housing and the pellicle surface, and the effect on the measurements of these ultrasonic sensors can be suppressed.

[0132] 9, the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 are arranged so that the length of the ultrasonic propagation path Path_1 of the first ultrasonic sensors 232, 233, 234, 235 is the same as the length of the ultrasonic propagation path Path_2 of the second ultrasonic sensors 332, 333, 334, 335. In other words, the support base 240 and the frame member 300 are positioned so that the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 are arranged as described above.

[0133] [Pellicle inspection device operation] The operation of the pellicle inspection device 1 according to this embodiment configured as described above will be described. First, the pellicle frame P is attached to the frame 31, and the position of the lower edge of the pellicle frame P in the height direction (Y direction) is adjusted by the adjustment mechanism 32. At this time, the pellicle support part 30 is located at an attachment position near the end of the surface plate 10 in the +X direction.

[0134] Next, the guide member 33 is moved in the −X direction along the groove 10f to move the pellicle frame P from the mounting position to the inspection position.

[0135] Once the pellicle frame P has moved to the inspection position, the pellicle film is inspected by the inspection unit 20. In this embodiment, foreign matter such as dust adhering to the pellicle film is detected from images captured by the camera 22. In addition, the tension measuring device 23 measures the tension applied to the pellicle film.

[0136] If dust or other foreign matter is detected adhering to the pellicle film, the foreign matter is removed by blowing air or other gas onto the foreign matter using a nozzle (not shown). This nozzle may also be used as the air nozzle 231 of the tension measuring device 23.

[0137] This inspection is first performed at the upper end position where camera 22 is located near the upper end of column 21. Inspection unit 20 moves guide member 33, i.e., pellicle frame P, a predetermined distance in the -X direction. In this way, the pellicle film stretched on pellicle frame P supported by pellicle support unit 30 is inspected one by one.

[0138] In this way, after performing the inspection while moving the camera 22 and tension measuring device 23 from the end in the -X direction to the end in the +X direction, the inspection unit 20 moves the camera 22 and tension measuring device 23 downward (in the -Y direction) along the pillar 21. Then, the inspection unit 20 similarly performs the inspection while moving the guide member 33, i.e., the pellicle frame P, in the +X direction.

[0139] By repeating this operation, the entire surface of the pellicle film stretched over the pellicle frame P can be inspected.

[0140] In the case of foreign particle inspection, the clean room where the inspection is performed has a downward flow, so there is a high possibility that foreign particles that have been blown away will re-adhere to the bottom. For this reason, when inspecting for foreign particles, the inspection is performed from top to bottom. If only the tension on the pellicle membrane is to be measured, the inspection can also be performed from bottom to top.

[0141] [Operation of tension measurement device] Next, the operation of the tension measuring device 23 will be described.

[0142] The tension measuring device 23 injects compressed air onto the tensioned pellicle film from an air nozzle 231. The tension measuring device 23 measures the displacement of the pellicle film in the perpendicular direction caused by the compressed air injected from the air nozzle 231 using first ultrasonic sensors 232, 233, 234, and 235.

[0143] Furthermore, the tension measuring device 23 uses second ultrasonic sensors 332, 333, 334, and 335 to measure the displacement of the pellicle film in the orthogonal direction outside the region on the pellicle film where displacement occurs due to the compressed air sprayed from the air nozzle 231.

[0144] The tension measuring device 23 subtracts the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, 335 from the displacement of the pellicle film measured by the first ultrasonic sensors 232, 233, 234, 235, thereby eliminating the influence of displacement of the pellicle film caused by, for example, downflow within a clean room, and measuring only the displacement of the pellicle film caused by compressed air sprayed from the air nozzle 231.

[0145] At this time, when calculating the difference between the displacement of the pellicle film measured by one of the first ultrasonic sensors and the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335, the control unit 237 of the tension measurement device 23 weights each of the displacements of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335 according to the distance from that one of the first ultrasonic sensors. In addition to the distance, weighting according to the order of measurement may also be added.

[0146] The control unit 237 calculates a weighted average of the pellicle film displacements weighted as described above, and regards this weighted average as the pellicle film displacement measured by the second ultrasonic sensors 332, 333, 334, and 335. In this way, the control unit 237 subtracts the pellicle film displacement calculated by the weighted average as described above as the pellicle film displacement measured by the second ultrasonic sensors 332, 333, 334, and 335 from the pellicle film displacement measured by that one first ultrasonic sensor, thereby being able to measure only the pellicle film displacement caused by the air sprayed from the air nozzle 231, as measured by that one first ultrasonic sensor.

[0147] [Effects of tension measurement device] As described above, the tension measuring device of this embodiment has at least one first ultrasonic sensor (four in this embodiment) arranged on a line passing through the center of the air nozzle 231, parallel to the tension direction in which the pellicle film is receiving tension (tension), concentrically centered on the air nozzle 231 that injects compressed air onto the pellicle film.

[0148] This makes it possible to measure the tension and tension anisotropy of the pellicle membrane in a non-contact manner by measuring the changes in the pellicle membrane when compressed air is sprayed onto it.

[0149] In addition, two first ultrasonic sensors should be installed concentrically around the air nozzle 231, on a line passing through the center of the air nozzle 231, parallel to the direction of tension in which the pellicle film is under tension, and sandwiching the air nozzle 231 therebetween.

[0150] This allows changes in the pellicle membrane to be measured on both sides of the position where the compressed air is injected in the direction of tension, making it possible to accurately measure the tension and tension anisotropy of the pellicle membrane.

[0151] The control unit 237 injects compressed air at a minute pressure that does not damage the pellicle membrane in pulses onto the pellicle membrane.

[0152] This makes it possible to accurately measure the tension and tension anisotropy of the pellicle membrane without damaging the pellicle membrane and while minimizing the effect on the acoustic waves.

[0153] In addition, the control unit 237 measures the time it takes for the pellicle membrane to return to half of the maximum change from the maximum change after the compressed air is injected as the half-return time, and measures the tension of the pellicle membrane based on this half-return time.

[0154] This reduces the influence of fluctuations in the injection pressure of the compressed air, enabling the tension of the pellicle membrane to be measured with high accuracy.

[0155] Furthermore, the control unit 237 measures the amount of change at the time when the pellicle film changes to the maximum after the compressed air is injected, and measures the anisotropy of the tension of the pellicle film from this amount of change.

[0156] This reduces the mutual influence of the directions in which tension is applied, making it possible to measure the anisotropy of the tension in the pellicle film with high accuracy.

[0157] 9, the amount of deformation of the pellicle film Pf caused by the compressed air sprayed from the air nozzle 231 increases the closer it is to the point where the compressed air hits, i.e., the position facing the center On of the air nozzle 231. Therefore, the pellicle film Pf is less deformed or no deformation occurs at all the farther it is from the position facing the center On of the air nozzle 231.

[0158] Even if an ultrasonic sensor is used to measure the amount of deformation in areas where no deformation has occurred in the pellicle film Pf, or where deformation has occurred but is minimal, it is not possible to measure an amount of deformation that is sufficient to accurately measure the anisotropy of the tension in the pellicle film Pf.

[0159] In Figure 9, if the deformation area suitable for measuring a deformation amount sufficient to accurately measure the anisotropy of the tension of the pellicle film Pf is the area surrounded by the dotted line Df, in order to measure a deformation amount sufficient to accurately measure the anisotropy of the tension of the pellicle film Pf, it is desirable that the distance D1 between the center of the air nozzle 231 and the center of the first ultrasonic sensors 232, 233, 234, 235 is small, and more preferably, the overlap between the suitable deformation area Df of the pellicle film Pf and the area hit by the ultrasonic waves is large.

[0160] The tension measuring device according to this embodiment is provided with an inclined surface 242a in the vicinity of the air nozzle 231 that reflects ultrasonic waves (transmitted waves) output from the first ultrasonic sensors 232, 233, 234, and 235 and ultrasonic waves (reflected waves) reflected by the pellicle film Pf (see FIG. 9).

[0161] 9, the line that passes through the center of the first ultrasonic sensors 232, 233, 234, and 235 and is perpendicular to the transmitting / receiving surface S of the ultrasonic sensors is defined as the center line Os. The center line Os coincides with the central axis of the ultrasonic waves (transmitted waves) output from the first ultrasonic sensors 232, 233, 234, and 235 and the ultrasonic waves (reflected waves) reflected by the pellicle film Pf, and is drawn so as to be reflected by the inclined surface 242a, just like the ultrasonic waves.

[0162] As described above, the tension measuring device according to this embodiment is configured to reflect the ultrasonic waves output from the first ultrasonic sensors 232, 233, 234, and 235 on the inclined surface 242a, and therefore the distance D1 between the center On of the air nozzle 231 and the above-mentioned center line Os can be reduced.

[0163] Therefore, the tension measuring device of this embodiment can bring the area where the ultrasonic waves hit closer to the position opposite the center On of the air nozzle 231, thereby increasing the overlap between the suitable deformation area Df of the pellicle film Pf and the area where the ultrasonic waves hit.

[0164] This allows the first ultrasonic sensors 232, 233, 234, and 235 to measure the deformation of the pellicle film Pf, which allows the anisotropy of the tension to be accurately measured. In other words, the deformation can be measured at a location where the deformation that allows the anisotropy of the tension of the pellicle film Pf to be accurately measured is reliably occurring. This makes it possible to measure the amount of deformation that allows the anisotropy of the tension of the pellicle film Pf to be accurately measured.

[0165] Furthermore, in the tension measurement device according to this embodiment, each inclined surface 242a is provided on a concentric circle centered on the air nozzle 231, on a line that is parallel to the tension direction in which the pellicle film Pf receives tension (tension) and that passes through the center On of the air nozzle 231, and between each of the first ultrasonic sensors 232, 233, 234, 235 and the center On of the air nozzle 231. Furthermore, the first ultrasonic sensors 232, 233, 234, 235 are installed with their transmitting / receiving surfaces S facing the respective inclined surfaces 242a so as to be able to receive ultrasonic waves reflected by the respective inclined surfaces 242a.

[0166] As a result, the tension measuring device of this embodiment reflects ultrasonic waves by the inclined surface 242a, so even if the first ultrasonic sensors 232, 233, 234, 235 are positioned away from the air nozzle 231, the first ultrasonic sensors 232, 233, 234, 235 are close to a position facing the center On of the air nozzle 231, and can measure the deformation of the pellicle film Pf, which allows accurate measurement of tension anisotropy.

[0167] Here, the first ultrasonic sensors 232, 233, 234, and 235 need to be sufficiently vibration-proofed in order to suppress the influence of, for example, reverberation waves and maintain their measurement accuracy. For this reason, an additional structure for vibration proofing needs to be provided around the ultrasonic sensors, and the structure around the ultrasonic sensors, including the ultrasonic sensors, tends to become larger. Examples of additional structures for vibration proofing include wrapping a lead plate around the first ultrasonic sensors 232, 233, 234, and 235, or enlarging the support member 245, such as the sensor housing 245a.

[0168] As described above, the tension measurement device according to this embodiment is configured such that the first ultrasonic sensors 232, 233, 234, and 235 are positioned away from the air nozzle 231 and ultrasonic waves are reflected by the inclined surface 242a. Therefore, even if the structure around the ultrasonic sensors, including the ultrasonic sensors, becomes larger, the influence of this can be avoided.

[0169] In other words, even if the structure around the ultrasonic sensor, including the ultrasonic sensor, is enlarged, the distance between the air nozzle 231 and the first ultrasonic sensors 232, 233, 234, and 235 does not increase. This makes it possible to avoid the effect of the area hit by the ultrasonic waves being moved away from the position facing the center On of the air nozzle 231 due to the enlargement of the structure around the ultrasonic sensor, including the ultrasonic sensor.

[0170] In addition, the tension measurement device according to this embodiment has support members 245 that support the first ultrasonic sensors 232, 233, 234, and 235, respectively, and the support members 245 are configured to be able to adjust the angles of the first ultrasonic sensors 232, 233, 234, and 235 relative to the inclined surface 242a, specifically, the rotation angles in the pitch direction and the rotation angles in the yaw direction.

[0171] As a result, the tension measurement device according to this embodiment can adjust the position on the pellicle film Pf at which the ultrasonic waves hit, and the angle at which the ultrasonic waves hit the pellicle film Pf. This makes it possible to adjust the positions and angles at which the first ultrasonic sensors 232, 233, 234, and 235 measure the deformation of the pellicle film Pf. In this way, if the position and angle of the ultrasonic waves relative to the pellicle film Pf can be adjusted, it is possible to find the positional relationship that maximizes the amplitude of the ultrasonic waves (reflected waves).

[0172] In this embodiment, the rotation angles of the first ultrasonic sensors 232, 233, 234, 235 in the pitch and yaw directions are adjustable as described above, but in addition to this, the sensor housing 245a or the bracket 245b may be configured to be movable in a direction perpendicular to the rotation axis of the sensor housing 245a and intersecting with the central axis Os. For example, the sensor housing 245a or the bracket 245b may be configured to be movable in a direction parallel to the transmitting / receiving surface S (see FIG. 8) of the ultrasonic sensor or in a direction parallel to the rotation axis of the bracket 245b.

[0173] This makes it possible to independently adjust the rotation angles of the first ultrasonic sensors 232, 233, 234, and 235 in the pitch and yaw directions and the position where the central axis Os of the ultrasonic waves strikes the pellicle film Pf.

[0174] Furthermore, the sensor housing 245a or the bracket 245b may be configured to be movable only in a direction perpendicular to the rotation axis of the sensor housing 245a and intersecting the central axis Os. In this case, it is possible to adjust only the position where the central axis Os of the ultrasonic wave hits the pellicle film Pf with a simple configuration.

[0175] In the tension measurement device according to this embodiment, the device body 242 has a hollow portion 242b that houses the air nozzle 231.

[0176] As a result, the tension measurement device according to this embodiment can prevent interference between the ultrasonic waves and the compressed air ejected from the air nozzle 231. As a result, it is possible to prevent the ultrasonic waves received by the first ultrasonic sensors 232, 233, 234, and 235 from being affected by the compressed air ejected from the air nozzle 231.

[0177] Next, the effects of providing the second ultrasonic sensors 332, 333, 334, and 335 in the tension measurement device according to this embodiment will be described.

[0178] 10 is a graph showing an example of the change in displacement of the pellicle film over time when compressed air is injected at time t1, measured using only the first ultrasonic sensors 232, 233, 234, and 235. Note that the graph in FIG. 10 shows the measurement results of one of the first ultrasonic sensors 232, 233, 234, and 235.

[0179] As shown in Figure 10, the displacement of the pellicle membrane during the period T from time t0 to time t1 immediately after the compressed air injection is the displacement caused by the compressed air. However, even after time t1 when the injection of the compressed air ends, displacement continues to occur in the pellicle membrane.

[0180] The displacement of the pellicle membrane after time t1 is, for example, a displacement caused by the downflow in the clean room. Thus, in addition to the displacement caused by the compressed air, a non-negligible displacement occurs in the pellicle membrane. For this reason, it is believed that the displacement of the pellicle membrane during the above-mentioned period T also includes the displacement caused by the downflow. Therefore, in order to accurately measure the displacement of the pellicle membrane caused by the compressed air, it is preferable to exclude the displacement caused by the aforementioned downflow.

[0181] Therefore, in the tension measurement device according to this embodiment, second ultrasonic sensors 332, 333, 334, and 335 are provided on the pellicle film to measure the displacement of the pellicle film outside of region R (see FIG. 9) where displacement occurs due to compressed air sprayed from air nozzle 231. Therefore, the second ultrasonic sensors 332, 333, 334, and 335 can measure the displacement of the pellicle film due to, for example, a downflow in a clean room.

[0182] Furthermore, the tension measurement device according to this embodiment measures only the displacement of the pellicle film caused by the air sprayed from the air nozzle 231 by subtracting the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335 from the displacement of the pellicle film measured by the first ultrasonic sensors 232, 233, 234, and 235. This makes it possible to eliminate the influence of the displacement of the pellicle film caused by, for example, a downflow in a clean room, and to accurately measure the displacement of the pellicle film caused by compressed air.

[0183] Furthermore, in the tension measuring device according to this embodiment, the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 are arranged so that the length of the ultrasonic propagation path Path_1 of the first ultrasonic sensors 232, 233, 234, 235 is the same as the length of the ultrasonic propagation path Path_2 of the second ultrasonic sensors 332, 333, 334, 335.

[0184] As a result, the tension measurement device according to this embodiment does not need to make corrections due to the difference in length between the propagation path Path_1 and the propagation path Path_2, and therefore the processing by the control unit 237 can be simplified.

[0185] In addition, in the tension measuring device of this embodiment, when calculating the difference between the displacement of the pellicle film measured by one of the first ultrasonic sensors and the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335, each of the displacements of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335 is weighted according to the distance from the one of the first ultrasonic sensors, a weighted average of the weighted displacements of the pellicle film is calculated, and the weighted average is regarded as the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335.

[0186] As a result, the tension measurement device according to this embodiment can more accurately measure the displacement of the pellicle film caused by, for example, a downflow, which may differ depending on the placement of the first ultrasonic sensors 232, 233, 234, and 235. As a result, each of the first ultrasonic sensors 232, 233, 234, and 235 can more accurately measure the displacement of the pellicle film caused by compressed air.

[0187] The average value of the displacement of the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335 may be measured as the displacement of the pellicle film caused by, for example, the downflow.

[0188] Furthermore, in this embodiment, the change in the pellicle film is measured using an ultrasonic sensor, but the change in the pellicle film may also be measured using an optical displacement sensor or the like.

[0189] Furthermore, in this embodiment, air is sprayed onto the pellicle film, but nitrogen, argon, or the like other than air may also be sprayed.

[0190] Furthermore, in this embodiment, four second ultrasonic sensors are arranged, but three second ultrasonic sensors may be arranged so that the lines connecting these three second ultrasonic sensors form an equilateral triangle.

[0191] In this embodiment, the displacement of the pellicle membrane due to compressed air may be measured multiple times and the average of these measurements may be calculated as the displacement of the pellicle membrane due to compressed air. In this case, the displacement of the pellicle membrane due to compressed air can be determined more accurately.

[0192] Furthermore, in this embodiment, measurements by the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 are performed in a predetermined order within a predetermined time period, but this is not limiting, and for example, the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 may be configured to be able to perform measurements independently of each other. In this case, the measurement timing of the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 can be synchronized.

[0193] The predetermined order mentioned above may be, for example, the first ultrasonic sensor 232, the first ultrasonic sensor 233, the first ultrasonic sensor 234, the first ultrasonic sensor 235, the second ultrasonic sensor 332, the second ultrasonic sensor 333, the second ultrasonic sensor 334, and the second ultrasonic sensor 335, but is not limited to this and can be set to any order based on experiments, etc. Note that it is also possible to eliminate the time lag between the ultrasonic sensors by interpolating the time lag between the ultrasonic sensors using an interpolation method such as linear interpolation or bicubic interpolation.

[0194] While an embodiment of the present invention has been disclosed, it will be apparent to one skilled in the art that modifications may be made thereto without departing from the scope of the present invention, and it is intended that all such modifications and equivalents be included in the following claims. [Explanation of symbols]

[0195] 1 Pellicle inspection equipment 23 Tension measuring device 231 Air nozzle (nozzle) 232, 233, 234, 235 First ultrasonic sensor 332, 333, 334, 335 Second ultrasonic sensor 236 Compressed air injection unit 237 Control Unit 240 Support stand 241 Post 242 Device body (inclined member) 242a Slanted surface (reflection part) 242b Hollow part 245 Support member 245a Sensor housing 245b bracket 245c shaft member 245d Shaft member 245e Fixing member 300 Frame members 340 Sensor Housing 340a surface S Transmitting and receiving surface (receiving surface) Path_1: Ultrasonic wave propagation path of the first ultrasonic sensor Path_2: Ultrasonic wave propagation path of the second ultrasonic sensor R Region where displacement occurs due to injected compressed air

Claims

1. a nozzle for injecting gas onto a pellicle membrane under a predetermined tension; At least one first ultrasonic sensor is provided on a line passing through the center of the nozzle, parallel to a tension direction in which the pellicle film is subjected to the tension, on a concentric circle centered on the nozzle, and measures the displacement of the pellicle film in a direction perpendicular to the tension direction caused by the gas ejected from the nozzle; and a plurality of second ultrasonic sensors that measure displacement of the pellicle film in the orthogonal direction outside a region on the pellicle film where displacement occurs due to the gas ejected from the nozzle; A tension measuring device comprising: a control unit that measures the tension applied to the pellicle film based on the difference between the displacement of the pellicle film measured by the first ultrasonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor.

2. The tension measuring device according to claim 1 , wherein two of the first ultrasonic sensors are provided on concentric circles centered on the nozzle, on a line that is parallel to the tension direction and passes through the center of the nozzle, with the nozzle in between.

3. 3. The tension measuring device according to claim 1, wherein the control unit injects the gas at a predetermined minute pressure in pulses onto the pellicle film.

4. The control unit measures the time it takes for the pellicle film to return to half of the maximum displacement from the maximum displacement after the gas is injected as a half-return time, and measures the tension applied to the pellicle film based on the half-return time.

5. The pellicle membrane is subjected to the tension in a plurality of directions, and at least one first ultrasonic sensor is provided in each of the plurality of directions on a line that is parallel to the tension direction and passes through the center of the nozzle; A tension measuring device described in any one of claims 1 to 4, wherein the control unit measures the maximum change amount when the pellicle film is displaced to its maximum after the gas is injected, and measures the anisotropy of the multiple tensions acting on the pellicle film based on the maximum change amount.

6. Further provided is a reflecting portion that reflects ultrasonic waves in the vicinity of the nozzle, The tension measuring device according to claim 1 , wherein the first ultrasonic sensor is disposed at a position farther away from the nozzle than the reflecting portion is.

7. a tilting member having an inclined surface that is inclined with respect to the jetting direction of the gas jetted from the nozzle, the tilting member being located on the straight line between the first ultrasonic sensor and the center of the nozzle; the reflecting portion is constituted by the inclined surface, The tension measuring device according to claim 6, wherein the first ultrasonic sensor is installed with a receiving surface facing the inclined surface so as to be able to receive ultrasonic waves reflected by the inclined surface.

8. a support member that supports the first ultrasonic sensor; 8. The tension measuring device according to claim 6, wherein the support member is configured to be able to adjust an angle of the first ultrasonic sensor relative to the reflecting portion.

9. The tension measuring device according to claim 7 , wherein the inclined member has a hollow portion that accommodates the nozzle.

10. 10. The tension measuring device according to claim 1, wherein the first ultrasonic sensor and the second ultrasonic sensor are arranged so that a length of a propagation path of ultrasonic waves of the first ultrasonic sensor and a length of a propagation path of ultrasonic waves of the second ultrasonic sensor are the same.

11. four first ultrasonic sensors are provided concentrically around the nozzle, four second ultrasonic sensors are provided on a concentric circle different from the first ultrasonic sensors, with the nozzle as the center, the first ultrasonic sensors and the second ultrasonic sensors are alternately arranged in a circumferential direction around the nozzle, The tension measuring device described in any one of claims 1 to 10, characterized in that when calculating the difference between the displacement of the pellicle film measured by one first ultrasonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor, the control unit weights each of the displacements of the pellicle film measured by the four second ultrasonic sensors according to the distance from the one first ultrasonic sensor, calculates a weighted average of the weighted displacements of the pellicle film, and regards the weighted average as the displacement of the pellicle film measured by the second ultrasonic sensor.

12. Injecting gas from a nozzle onto a pellicle membrane under a predetermined tension; A step of measuring the displacement of the pellicle film in a direction perpendicular to the tension direction, in which the pellicle film is subjected to the tension, caused by the gas ejected from the nozzle, using at least one first ultrasonic sensor provided on a concentric circle centered on the nozzle and on a line passing through the center of the nozzle, parallel to the tension direction; measuring, on the pellicle film, a displacement of the pellicle film in the orthogonal direction outside a region where displacement occurs due to the gas ejected from the nozzle, using a plurality of second ultrasonic sensors; A tension measurement method comprising a step of measuring the tension acting on the pellicle film based on the difference between the displacement of the pellicle film measured by the first ultrasonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor.

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