JP2023107415A - Tension measuring device and tension measuring method - Google Patents

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

The present invention relates to a tension measuring device and a tension measuring method for measuring the tension of a stretched film such as a pellicle film.

2. Description of the Related Art In a photolithography 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 to a resist layer on a photosensitive substrate through an optical system of an exposure device.

In order to prevent foreign matter such as dust from adhering to the pattern area, the mask generally has a pellicle film stretched over a pellicle frame arranged to surround the pattern area so as to cover the pattern area.

The pellicle membrane must be stretched on the pellicle frame with a predetermined tension, and it is desirable that the vertical and horizontal tensions be the same.

The pellicle membrane is mounted on a rectangular pellicle frame. When installing, the pellicle is attached to the pellicle frame while being pulled in directions (longitudinal and lateral directions) parallel to the long and short sides of the pellicle frame.

At this time, it is desirable that the tension in the vertical direction and the tension in the horizontal direction are equal, and it is required to measure the anisotropy, which is the difference between the tension in the vertical direction and the tension in the horizontal direction.

In addition, since the pellicle film is a very thin film on the order of microns, it is impossible to measure the tension by contact, and non-contact measurement of the tension is required.

Conventionally, a tension measuring device described in Patent Document 1 is known as a device for measuring the tension of a pellicle film and the anisotropy of the tension in a non-contact manner. In this tension measurement device, compressed air is injected onto the pellicle film, and changes in the pellicle film at that time are detected by four ultrasonic sensors, thereby measuring the tension and anisotropy of the pellicle film without contact. do.

JP 2021-179592 A

However, in the tension measuring device described in Patent Document 1, when measuring the tension of the pellicle film and the anisotropy of the tension, if the pellicle film shakes due to factors other than compressed air, the tension of the pellicle film and the tension of the pellicle film may be affected. There was a possibility that the anisotropy measurement could not be performed accurately.

For example, in a clean room where a pellicle film tension measuring device is installed, a downflow system is mainly used as an air conditioning/airflow system, so the pellicle film may shake due to the downflow. If the pellicle film shakes under the influence of the downflow, the tension of the pellicle film and the anisotropy of the tension cannot be measured accurately.

Here, if the amplitude of the shaking of the pellicle film caused by the injection of compressed air from the tension measuring device is sufficiently larger than the shaking of the pellicle film caused by the downflow, the above problem will not occur. However, if a strong compressed air is injected to the pellicle film so as not to cause the above problem, the pellicle film will be plastically deformed or destroyed. Therefore, in reality, the amplitude of the pellicle film sway caused by the downflow is approximately the same as or greater than the amplitude of the pellicle film sway caused by the injection of compressed air from the tension measuring device. can only measure Under such restrictions, there is a need for a measuring device and method capable of measuring the tension of the pellicle film.

The present invention has been made in view of the circumstances described above, and even if the pellicle film shakes due to factors other than jetting gas, the tension of the pellicle film and the anisotropy of the tension can be adjusted without contact. It is an object of the present invention to provide a tension measuring device and a tension measuring method capable of accurate measurement.

The tension measuring device of the present invention includes a nozzle for injecting gas to a pellicle film to which a predetermined tension is applied, and a nozzle that is concentric with the nozzle and parallel to the tension direction, which is the direction in which the pellicle film receives the tension. at least one first ultrasonic sensor provided on a straight line passing through the center of the nozzle and measuring displacement of the pellicle film in a direction perpendicular to the direction of tension caused by the gas ejected from the nozzle; a plurality of second ultrasonic sensors for measuring displacement of the pellicle film in the orthogonal direction outside a region on the pellicle film in which displacement is caused by the gas injected from the nozzle; 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 sonic sensor and the displacement of the pellicle film measured by the second ultrasonic sensor. And prepare.

With this configuration, the tension measuring device of the present invention measures the displacement in the direction perpendicular to the tension direction of the pellicle film by the gas jetted from the nozzle by the first ultrasonic sensor, and measures the tension applied to the pellicle film. is measured. Therefore, the tension of the pellicle film and the anisotropy of the tension can be measured without contact.

Further, the tension measuring device of the present invention is provided with a plurality of second ultrasonic sensors for measuring the displacement of the pellicle film in the orthogonal direction outside the region on the pellicle film where the displacement occurs due to the gas injected from the nozzle, The tension applied to the pellicle membrane is measured based on the difference between the displacement of the pellicle membrane measured by the first ultrasonic sensor and the displacement of the pellicle membrane measured by the second ultrasonic sensor. ing.

As a result, even if the pellicle film shakes due to factors other than gas injection, such as downflow in a clean room, the tension measuring device of the present invention can detect the pellicle film caused by factors other than gas injection. The influence of displacement can be eliminated, and the displacement of the pellicle film caused by 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.

Further, in the tension measuring device of the present invention, the first ultrasonic sensor is provided on two concentric circles centered on the nozzle on a straight line parallel to the direction of tension and passing through the center of the nozzle with the nozzle interposed therebetween. It has a configuration that

With this configuration, the tension measuring device of the present invention can measure the change in the pellicle film on both sides of the position where the gas is injected in the direction of tension in which the pellicle film is tensioned. and tension anisotropy can be measured.

Further, in the tension measuring device of the present invention, the control section has a configuration for injecting the gas at a predetermined minute pressure in a pulsed manner to the pellicle film.

With this configuration, the tension measuring device of the present invention can accurately measure the tension of the pellicle film and the anisotropy of the tension without damaging the pellicle film and suppressing the influence on sound waves.

Further, in the tension measuring device of the present invention, the control unit measures the time for returning from the maximum displacement of the pellicle film after the injection of the gas to half of the maximum amount of change as a half-return time. It has a configuration for measuring the tension applied to the pellicle film based on the return time.

With this configuration, the tension measuring device of the present invention can suppress the influence of fluctuations in gas injection pressure and accurately measure the tension of the pellicle film.

Further, in the tension measuring device of the present invention, the pellicle film receives the tension in a plurality of directions, and each of the plurality of directions has at least one tension on a straight line parallel to the tension direction and passing through the center of the nozzle. The first ultrasonic sensor is provided, and the control unit measures a maximum change amount when the pellicle film is displaced to a maximum after the gas is injected, and measures the maximum change amount of the pellicle film based on the maximum change amount. It has a configuration for measuring the anisotropy of the plurality of tensions applied to the film.

With this configuration, the tension measuring device of the present invention can suppress the mutual influence of the direction in which the tension is applied, and accurately measure the anisotropy of a plurality of tensions of the pellicle film.

Further, the tension measuring device of the present invention further includes a reflecting section that reflects ultrasonic waves in the vicinity of the nozzle, and the first ultrasonic sensor is positioned further away from the nozzle than the reflecting section. Having a configuration in place.

With this configuration, the tension measuring device of the present invention can reduce the distance between the center of the nozzle and the center line passing through the center of the first ultrasonic sensor and perpendicular to the transmitting/receiving surface of the first ultrasonic sensor. can. Therefore, the first ultrasonic sensor can measure the deformation of the pellicle film that is close to the position facing the center of the nozzle and that can accurately measure the anisotropy of the tension. As a result, it is possible to measure the amount of deformation that can accurately measure the anisotropy of the tension of the pellicle film.

Further, in the tension measuring device of the present invention, an inclination inclined with respect to the ejection direction of the gas ejected from the nozzle is provided on the straight line and between the first ultrasonic sensor and the center of the nozzle. An inclined member having a surface is further provided, the reflecting portion is configured by the inclined surface, and the first ultrasonic sensor has a receiving surface so as to be able to receive ultrasonic waves reflected by the inclined surface. It has the structure installed toward the said inclined surface.

With this configuration, the tension measuring device of the present invention reflects the ultrasonic waves by the inclined surface of the inclined member, so that even if the first ultrasonic sensor is arranged at a position away from the nozzle, the tension measuring device faces the center of the nozzle. The deformation of the pellicle film that is close to the position and can accurately measure the anisotropy of the tension can be measured by the first ultrasonic sensor.

Further, the tension measuring device of the present invention further includes a supporting member that supports the first ultrasonic sensor, and the supporting member is configured to be able to adjust the angle of the first ultrasonic sensor with respect to the reflecting section. It is

With this configuration, the tension measuring device of the present invention can adjust the position of the pellicle membrane to which ultrasonic waves hit. Thereby, the position at which the first ultrasonic sensor measures the deformation of the pellicle membrane can be adjusted.

Moreover, in the tension measuring device of the present invention, the inclined member has a hollow portion that accommodates the nozzle.

With this configuration, the tension measuring device of the present invention can prevent interference between the gas jetted from the nozzle and the ultrasonic wave. Accordingly, it is possible to prevent the ultrasonic waves received by the first ultrasonic sensor from being affected by the gas jetted from the nozzle.

Further, in the tension measuring device of the present invention, 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. It has a configuration in which the first ultrasonic sensor and the second ultrasonic sensor are arranged.

With this configuration, the tension measuring device of the present invention needs to add a correction or the like due to the difference between 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. Therefore, the processing by the control unit can be simplified.

Further, in the tension measuring device of the present invention, the first ultrasonic sensor is provided four concentrically around the nozzle, and the second ultrasonic sensor is arranged around the first ultrasonic sensor around the nozzle. Four ultrasonic sensors are provided on different concentric circles, and the first ultrasonic sensor and the second ultrasonic sensor are alternately arranged in a circumferential direction around the nozzle, and the control unit is the difference between the displacement of the pellicle membrane measured by one of the first ultrasonic sensors and the displacement of the pellicle membrane measured by the second ultrasonic sensor, the four second each of the displacements of the pellicle membrane measured by the ultrasonic sensors is weighted according to the distance from the first ultrasonic sensor, and a weighted average of the weighted displacements of the pellicle membrane is obtained and the weighted average is regarded as the displacement of the pellicle membrane measured by the second ultrasonic sensor.

With this configuration, the tension measuring device of the present invention can more accurately measure the displacement of the pellicle membrane caused by, for example, downflow, which may differ depending on the arrangement of the first ultrasonic sensor. Therefore, each of the first ultrasonic sensors can more accurately measure the displacement of the pellicle film caused by the gas ejected from the nozzle.

Further, the tension measuring method of the present invention includes the steps of: injecting gas from a nozzle onto a pellicle film to which a predetermined tension is applied; At least one first ultrasonic wave that displaces the pellicle film in an orthogonal direction perpendicular to a certain tension direction on a straight line that is parallel to the tension direction and passes through the center of the nozzle on a concentric circle centered on the nozzle. measuring with a sensor; and measuring, with a plurality of second ultrasonic sensors, the displacement of the pellicle film in the orthogonal direction outside the region on the pellicle film in which displacement occurs due to the gas injected from the nozzle. and a step applied to the pellicle membrane based on the difference between the displacement of the pellicle membrane measured by the first ultrasonic sensor and the displacement of the pellicle membrane measured by the second ultrasonic sensor. and measuring the tension applied.

According to the tension measuring method of the present invention, the first ultrasonic sensor measures the displacement in the direction perpendicular to the tension direction of the pellicle film by the gas injected from the nozzle, and measures the tension applied to the pellicle film. be done. Therefore, the tension of the pellicle film and the anisotropy of the tension can be measured without contact.

Further, the displacement of the pellicle film measured by the first ultrasonic sensor and the displacement of the pellicle film in the orthogonal direction outside the region on the pellicle film where the displacement occurs due to the gas injected from the nozzle are measured. The tension applied to the pellicle film is measured based on the difference between the displacement of the pellicle film measured by the second ultrasonic sensor and the displacement of the pellicle film. As a result, even if the pellicle film shakes due to factors other than gas injection, such as downflow in a clean room, the effects of displacement of the pellicle film caused by factors other than gas injection can be eliminated. 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.

The present invention provides a tension measuring device and a tension measuring device that can accurately measure the tension and tension anisotropy of the pellicle film without contact even if the pellicle film is shaken by factors other than jetting gas. can provide a method.

FIG. 1 is a front view of a pellicle inspection device according to one embodiment of the present invention. FIG. 2 is a plan view of a pellicle inspection device according to one embodiment of the present invention. FIG. 3 is a block diagram of a tension measuring device according to one embodiment of the present invention. FIG. 4 is a diagram showing an example of changes in the pellicle film by the tension measuring device according to one embodiment of the present invention. FIGS. 5A and 5B are diagrams showing modifications of the pellicle film by the tension measuring device according to the embodiment of the present invention, FIG. b) is a diagram showing an example in which left and right tensions are large. FIG. 6 is a perspective view of a tension measuring device according to one embodiment of the present invention. FIG. 7 is a side view of the tension measuring device according to one embodiment of the present invention. FIG. 8 is a side cross-sectional view cut along the center of the air nozzle of the tension measuring device according to one embodiment of the present invention. FIG. 9 is a side view showing the distance between the center of the air nozzle and the center of each ultrasonic sensor in the tension measuring device according to one embodiment of the present invention. FIG. 10 is a graph showing temporal changes in the amount of deformation of the pellicle film during tension measurement by the tension measurement device according to the embodiment of the present invention.

A pellicle inspection apparatus according to an embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, the direction orthogonal to the paper surface is the X direction, the vertical direction of the paper surface is the Y direction, and the direction orthogonal to the X and Y directions is the Z direction. In addition, in FIG. 2, illustration is abbreviate|omitted about a part of structure.

[Pellicle inspection device]
In FIG. 1, a pellicle inspection apparatus 1 according to an embodiment of the present invention supports, for example, a rectangular pellicle frame P on which a pellicle film to be inspected is stretched in a substantially vertical direction, and a camera or the like is installed in a vertical direction. It is an inspection device that inspects a pellicle film stretched on a pellicle frame P by moving it.

1 and 2, the pellicle inspection apparatus 1 includes a surface plate 10, an inspection section 20, a pellicle support section 30, and a vibration isolation table 50. As shown in FIG.

The surface plate 10 is configured as a stage, and is supported on vibration isolation tables 50 installed at a plurality of locations (six locations) on the installation surface F. As shown in FIG.

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.

Substantially cubic concave portions 10b and 10c are formed on the lower surface 10a of the platen 10. As shown in FIG. One recess 10b is formed at each of the four corners of the lower surface 10a. The recesses 10c are formed at two locations in total, one each along the long side of the lower surface 10a. Thus, the recessed portions 10b and the recessed portions 10c are formed at a total of six locations. Distortion of the platen 10 can be reduced by providing the recess 10c in addition to the recess 10b.

A vibration isolation table 50 placed on the installation surface F is provided inside the recess 10b and the recess 10c. The bottom surfaces of the recess 10b and the recess 10c are support surfaces 10d supported by the anti-vibration table 50. As shown in FIG.

As shown in FIG. 1, the height of the anti-vibration table 50 is higher than the depths of the recesses 10b and 10c. Therefore, the surface plate 10 is mounted on the installation surface F via the vibration isolation table 50 because the vibration isolation table 50 supports the support surface 10d.

A groove 10f is formed in the upper surface 10e of the platen 10. As shown in FIG. The groove 10f is formed along the longitudinal direction (X direction) of the surface plate 10 at a position that does not overlap with the concave portion 10b and the concave portion 10c in plan view (see FIG. 2).

The depth of the groove 10f is sufficiently smaller than the thickness of the platen 10. As shown in FIG. Therefore, even if the grooves 10f are formed, the rigidity of the surface plate 10 can be sufficiently high.

The groove 10f supports the pellicle support portion 30 so as to be movable in the X direction. By using the groove 10f as a guide for moving the pellicle support section 30, the heights of the inspection section 20 and the pellicle support section 30 can be lowered, thereby lowering the center of gravity.

The depth of the groove 10f is set so that the optical axis of the camera 22 when the tension measuring device 23 contacts the upper surface 10e of the surface plate 10 coincides with the lower end of the pellicle frame P supported by the pellicle support portion 30. be done. That is, the camera 22 and the tension measuring device 23 can inspect the entire surface of the pellicle frame P supported by the pellicle support section 30 .

The inspection unit 20 includes a column 21 protruding upward from the surface plate 10, a camera 22 and a tension measuring device 23 provided on the column 21, a support unit 24 that supports the pellicle support unit 30 at the inspection position, Consists of

The column 21 is 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, it is preferable that the column 21 is hollow.

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

The tension measuring device 23 measures the tension of the pellicle film stretched on the pellicle frame P. As shown in FIG.

A moving part (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 part so that its optical axis is parallel to the Z-axis.

The camera 22 and the tension measuring device 23 move vertically by moving the moving part in the vertical direction (Y direction). The moving unit moves the camera 22 and the tension measuring device 23 to the initial position where the tension measuring device 23 contacts the upper surface 10e of the surface plate 10, and the upper end position where the camera 22 is located near the upper end of the column 21 (two points in FIG. position indicated by the dashed line) along the pillar 21 .

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.

The pellicle support section 30 supports the pellicle frame P. As shown in FIG. The pellicle support section 30 includes a frame 31 , an adjustment mechanism 32 and a guide member 33 .

The frame 31 is formed in a frame shape so as to surround the outer periphery of the pellicle frame P supported vertically. The frame 31 supports the pellicle frame P so that the pellicle membrane of the pellicle frame P is parallel to the XY plane.

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

[Main Configuration of Tension Measuring Device]
Next, the tension measuring device 23 will be described.
As shown in FIG. 3, the tension measuring device 23 has, as main components, an air nozzle 231 as a nozzle, a first ultrasonic sensor 232, a first ultrasonic sensor 233, and 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, and a compressed air injection It includes a unit 236 and a control unit 237 .

(air nozzle)
The air nozzle 231 injects air (gas) compressed by the compressed air injection part 236 onto the pellicle film. The tension measuring device 23 is provided in the moving part so that the air jetted from the air nozzle 231 hits the pellicle film substantially perpendicularly.

(First ultrasonic sensor)
The first ultrasonic sensors 232, 233, 234, and 235 transmit ultrasonic waves, receive ultrasonic waves reflected from objects, and measure distances to the objects.

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 on the right side of the air nozzle 231 (see FIG. 8). The first ultrasonic sensor 235 is provided on the left side of the air nozzle 231 (see FIG. 8).

The first ultrasonic sensors 232 , 233 , 234 , 235 are provided on a plane parallel to the pellicle film on a concentric circle centered on the air nozzle 231 in the vertical and horizontal directions.

The first ultrasonic sensor 232 and the first ultrasonic sensor 233 are provided so that their centers are positioned on the same straight line in the vertical direction (Y direction). The first ultrasonic sensor 234 and the first ultrasonic sensor 235 are provided so that their centers are positioned on the same straight line in the horizontal direction (X direction).

The first ultrasonic sensors 232, 233, 234, and 235 are installed in the direction in which the pellicle film stretched on the pellicle frame P receives tension (hereinafter referred to as the “tension direction”). should be placed between In this embodiment, since the pellicle frame P is rectangular, the pellicle membrane receives tension in two directions, ie, the vertical direction and the horizontal direction. Therefore, the installation positions of the first ultrasonic sensors 232, 233, 234, and 235 are four directions of up, down, left, and right.

The first ultrasonic sensors 232, 233, 234, and 235 measure the displacement of the pellicle film in a direction orthogonal to the above tension direction (hereinafter referred to as "perpendicular direction") due to air jetted from the air nozzle 231. It's like

(Second ultrasonic sensor)
The second ultrasonic sensors 332, 333, 334, and 335, like the first ultrasonic sensors, transmit ultrasonic waves, receive ultrasonic waves reflected from objects, and measure the distance to the objects. do.

As shown in FIG. 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 on the left side of the first ultrasonic sensor 233 and below the first ultrasonic sensor 235 . The second ultrasonic sensor 335 is provided on the right side of the first ultrasonic sensor 233 and below the first ultrasonic sensor 234 .

The second ultrasonic sensors 332 , 333 , 334 , 335 are provided on concentric circles different from the first ultrasonic sensors 232 , 233 , 234 , 235 with the air nozzle 231 as the center.

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

The second ultrasonic sensors 332, 333, 334, and 335 detect the above-described orthogonal direction on the pellicle film outside the region where displacement occurs due to the air jetted from the air nozzle 231 (the region indicated by R in FIG. 9). It measures the displacement of the pellicle membrane. The second ultrasonic sensors 332, 333, 334, 335 measure displacement of the pellicle membrane due to, for example, downflow in the clean room.

The second ultrasonic sensors 332, 333, 334, and 335 are capable of measuring outside the area where displacement occurs due to the air jetted from the air nozzle 231 (the area indicated by R in FIG. 9). The displacement of the pellicle film is measured at a position close to the region R where displacement occurs due to the air injected from 231 .

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

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

The control unit 237 causes the compressed air injection unit 236 to inject air from the air nozzle 231 onto the pellicle film stretched on the pellicle frame P at a predetermined pressure for a predetermined time, and the dent amount of the pellicle film receiving the air is set to the first are measured by the ultrasonic sensors 232, 233, 234, and 235.

The control unit 237 causes the pellicle film to be injected with a pulsed compressed air having a predetermined minute pressure. For example, the control unit 237 causes the pellicle film to be injected with minute-pressure compressed air that does not damage the pellicle film in a pulsed manner. To not damage the pellicle film means to prevent plastic deformation of the pellicle film. For example, the tension applied to the pellicle membrane does not weaken.

At the moment the compressed air is injected, the adiabatically expanded air spreads to the tip of the air nozzle 231, so the air temperature changes and affects the speed of sound. The cold air does not disturb the measurement because it does not reach the temperature, it just pushes the air that was there before.

On the other hand, since there is also air behind the pellicle film in the direction of the compressed air injection, it is difficult to deform with pulsed injection regardless of the tension of the pellicle film. Therefore, the injection pressure suitable for measurement should be set. .

FIG. 4 is a graph showing an example of the amount of deformation of the pellicle film after the injection of compressed air (start of blowing) is started.

The maximum pellicle deformation amount and the deformation return speed shown in FIG. 4 are highly likely to be affected by fluctuations in the injection pressure of the compressed air, and it is necessary to consider the stability of the solenoid valve of the compressed air injection section 236 as well. On the other hand, for example, if the return time is half (“half return time” in the figure), it is considered that the change due to the injection pressure of the compressed air is small.

For this reason, the control unit 237 of the present embodiment measures, as a half-return time, the time it takes for the pellicle film to return from the time when the pellicle film undergoes the maximum change after the injection of the compressed air to the half of the maximum change amount, and based on this half-return time. to measure the tension of the pellicle membrane.

The range of the pellicle film deformed by pinpoint injection of compressed air is limited to about 50 mm in diameter. It is measured by first ultrasonic sensors 232, 233, 234, 235 each having a diameter of 10 mm, for example.

For example, the control unit 237 measures half-return times within a diameter of 10 mm with the first ultrasonic sensors 232, 233, 234, and 235, respectively, calculates the average value of the measured half-return times, and calculates the calculated average value. to calculate the tension of the pellicle membrane.

The half-return time is determined by the ultrasonic sensors (the first ultrasonic sensor 232 and the first ultrasonic sensor 233, the first ultrasonic sensor 234 and the first ultrasonic sensor 235 ) may be averaged.

Further, instead of the half-return time of the pellicle film when the compressed air is injected, the maximum amount of change of the pellicle film or the return speed may be used to determine the strength of the tension.

On the other hand, in order to measure the anisotropy of tension, for example, when trying to measure the ratio of vertical and horizontal tension, the vertical tension affects the horizontal direction, and the horizontal tension affects the vertical direction. It is inappropriate to measure with

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

FIG. 5 shows a line connecting points of equal variation when the pellicle film after the injection of compressed air changes to the maximum (when the portion corresponding to the air nozzle 231 to which the compressed air is injected is pushed most). FIG. 4 is a diagram showing;

As shown in FIG. 5(a), if the figure connecting points with the same amount of change is close to a circle, that is, if the amounts of change measured by the first ultrasonic sensors 232, 233, 234, and 235 are If they are approximately equal, the tensions in the top, bottom, left, and right are uniform.

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

The control unit 237 detects, for example, the maximum pellicle deformation amounts measured by the first ultrasonic sensors 232, 233, 234, and 235, respectively, in the direction in which the tension is applied to the ultrasonic sensors (first ultrasonic wave The measurements of sensor 232 and first ultrasonic sensor 233, first ultrasonic sensor 234 and first ultrasonic sensor 235) are averaged. For example, if the difference in the average value of the maximum pellicle deformation amount for each direction in which tension is applied is within a predetermined range, the control unit 237 determines that the tension in each direction in which tension is applied is substantially uniform. do.

For example, the control unit 237 injects compressed air in pulses, performs measurement with one of the first ultrasonic sensors 232, 233, 234, and 235 with one injection, and performs measurement four times. Measure up, down, left and right.

Note that the distance between the pellicle film and the first ultrasonic sensors 232, 233, 234, 235, that is, the length of the ultrasonic wave propagation path of the first ultrasonic sensors 232, 233, 234, 235 is 1/2. is, for example, about 50 mm. Here, the ultrasonic wave propagation path is, for example, the path through which the ultrasonic wave emitted from the sensor vibration surface of the ultrasonic sensor is reflected by the pellicle film and is received again by the ultrasonic sensor.

The control unit 237 measures the amount of deformation of the pellicle film caused by downflow in the clean room, for example, using the second ultrasonic sensors 332 , 333 , 334 and 335 . Outside the area where displacement occurs due to the air jetted from the air nozzle 231, the pellicle film is affected by downflow or the like in one of the orthogonal directions (for example, the direction away from the tension measuring device 23) or in the other direction (for example, the direction away from the tension measuring device 23). 23).

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.

The controller 237 controls the displacement of the pellicle membrane measured by the first ultrasonic sensors 232, 233, 234, and 235 and the displacement of the pellicle membrane measured by the second ultrasonic sensors 332, 333, 334, and 335. , the tension applied to the pellicle film is measured.

Specifically, the control unit 237 converts the displacement of the pellicle membrane measured by the first ultrasonic sensors 232 , 233 , 234 and 235 into the pellicle displacement measured by the second ultrasonic sensors 332 , 333 , 334 and 335 . By subtracting the displacement of the film, it is possible to eliminate the influence of the displacement of the pellicle film caused by the downflow in the clean room, for example, and measure only the displacement of the pellicle film caused by the air injected from the air nozzle 231.

[Specific Configuration of Tension Measuring Device]
Next, a specific configuration of the tension measuring device 23 will be described with reference to FIGS. 6 to 9. FIG.

As shown in FIGS. 6 to 8, the tension measuring device 23 includes a support base 240, a column 241, and a device main body 242. As shown in FIG. The support base 240 is attached to a moving portion (not shown) provided on the pillar 21 (see FIG. 1). The support 241 has its lower end fixed to the upper surface of the support base 240 . An apparatus main body 242 is fixed to the upper end of the support 241 . 6 to 8, the surface of the tension measuring device 23 facing the pellicle film is defined as the front surface, and the surface opposite to the front surface is defined as the rear surface.

The tension measuring device 23 is configured to be vertically movable along the column 21 by attaching the support base 240 to a moving portion (not shown) provided on the column 21 (see FIG. 1).

Note that the tension measuring device 23 may be configured without the support base 240 and the strut 241 . In this case, the tension measuring device 23 is attached to a moving portion (not shown) in which the device main body 242 is provided on the pillar 21 (see FIG. 1).

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

(support member)
Each of the first ultrasonic sensors 232, 233, 234, and 235 is supported by each supporting member 245, so that the air nozzle 231 (see FIG. 8) is separated from the inclined surface 242a of the device main body 242, which will be described later. placed in the position

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.

As shown in FIG. 8, each of the first ultrasonic sensors 232 , 233 , 234 , 235 is held within the sensor housing 245 a by two O-rings 250 . The two O-rings 250 are separated from each other in a direction perpendicular to the transmission/reception plane S of each of the first ultrasonic sensors 232, 233, 234, and 235, and wrapped around the circumference of the As a result, it is possible to prevent the vibration transmitted from the first ultrasonic sensors 232, 233, 234, 235 to the sensor housing 245a from being transmitted to other members (for example, metal parts).

The sensor housing 245a is rotatable with respect to the bracket 245b in the direction indicated by the arrow P in the figure (hereinafter referred to as the "pitch direction") about the shaft member 245c as a fulcrum, that is, the transmitting/receiving surface S of the ultrasonic sensor, which will be described later. It is supported by the bracket 245b so that the angle formed with the inclined surface 242a can be adjusted.

The shaft member 245c functions both as a rotating shaft for the sensor housing 245a and as a fixing member that fixes the sensor housing 245a at an adjusted angle so that it cannot rotate.

Further, as shown in FIG. 7, the bracket 245b is rotatable with respect to the device main body 242 in the direction indicated by the arrow Y (hereinafter referred to as "yaw direction") about the shaft member 245d. The bracket 245b is supported by the device main body 242 so that the angle of rotation on the installation plane of the bracket 245b to 242 can be adjusted. Thereby, the rotation angle of the sensor housing 245a in the yaw direction can be adjusted.

The bracket 245b is non-rotatably fixed to the device main body 242 at the adjusted rotation angle by two fixing members 245e.

Note that the support member 245 is not limited to the above-described configuration as long as the rotation angles of the sensor housing 245a in the pitch direction and the yaw direction can be adjusted. Further, the support member 245 may be configured to be able to adjust the rotation angle of the sensor housing 245a in either the pitch direction or the yaw direction.

(inclined surface)
As shown in FIG. 8, an apparatus main body 242 has an inclined surface 242a on the front side (left side in FIG. 8). The inclined surfaces 242a are formed vertically and horizontally according to the first ultrasonic sensors 232, 233, 234, and 235, respectively. The apparatus main body 242 according to this embodiment constitutes an inclined member.

Each inclined surface 242a is inclined so as to gradually approach the center (indicated by the dashed line in FIG. 8) On of the air nozzle 231 as it goes from the back side of the device main body 242 to the front end side. Therefore, the shape of the front side of the device main body 242 is a truncated quadrangular pyramid shape with the front end of the device main body 242 as the upper surface, or a quadrangular pyramid shape with the front end of the device main body 242 as the apex.

Each inclined surface 242a is on a straight line passing through the center On of the air nozzle 231 in parallel with the tension direction in which the pellicle film is subjected to tension (tension) concentrically around the air nozzle 231. , 233 , 234 , 235 and the center On of the air nozzle 231 .

In the vicinity of the air nozzle 231, each inclined surface 242a receives 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. It functions as a reflector that reflects the

In this embodiment, the configuration in which the apparatus main body 242 is formed with the inclined surface 242a has been described, but the apparatus main body 242 and a separate member may be formed with the inclined surface 242a.

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

(Hollow part)
As shown in FIG. 8, the device main body 242 has a hollow portion 242b that accommodates the air nozzle 231. As shown in FIG.

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

It is preferable that the front open end (the left end in FIG. 8) of the hollow portion 242b be located closer to the front than the front end of the air nozzle 231. As shown in FIG.

(Frame member)
As shown in FIG. 6, the tension measuring device 23 has a frame member 300 that surrounds the device body 242 . The frame member 300 is attached to a moving portion (not shown) provided on the pillar 21 (see FIG. 1).

Inside the four corners of the frame member 300, sensor housings 340 are attached to hold the second ultrasonic sensors 332, 333, 334, and 335, respectively. Here, the second ultrasonic sensors 332, 333, 334, and 335 are located outside the region R (see FIG. 9), and more preferably at positions close to the region R where displacement occurs due to the air jetted from the air nozzle 231. The lengths of the four sides of the frame member 300 are set so that the displacement of the pellicle film can be measured.

Each of the second ultrasonic sensors 332, 333, 334, 335 is held in each sensor housing 340 via two O-rings (not shown), similar to the first ultrasonic sensors 232, 233, 234, 235. It is desirable that

The sensor housings 340 of the second ultrasonic sensors 333 and 334 incline toward the back as the surface 340a thereof goes leftward in FIG. The sensor housings 340 of the second ultrasonic sensors 332 and 335 incline rearward as the surface 340a thereof goes rightward in FIG.

As a result, among the ultrasonic waves output from the second ultrasonic sensors 332, 333, 334, and 335 and reflected by the pellicle film, the ultrasonic waves returning to the second ultrasonic sensors 332, 333, 334, and 335 are detected. Ultrasonic waves other than the ultrasonic waves are reflected toward the outside of the frame member 300 (outward left and right in this embodiment) by the inclined surface 340 a of the sensor housing 340 . Therefore, among the ultrasonic waves reflected by the pellicle film, ultrasonic waves other than the ultrasonic waves returning to the second ultrasonic sensors 332, 333, 334, and 335 are reflected multiple times between the sensor housing and the pellicle surface. There is no interference with the ultrasonic waves returning to the second ultrasonic sensors 332, 333, 334, 335 and the first ultrasonic sensors 232, 233, 234, 235, and the influence on the measurement of these ultrasonic sensors is eliminated. can be suppressed.

Further, as shown in FIG. 9, the length of the propagation path Path_1 of the ultrasonic waves of the first ultrasonic sensors 232, 233, 234, and 235 and the length of the ultrasonic waves of the second ultrasonic sensors 332, 333, 334, and 335 The first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 are arranged so that the propagation path Path_2 is the same. That is, the support base 240 and the frame member 300 are positioned such that the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 are arranged as described above. It is

[Operation of Pellicle Inspection Device]
The operation of the pellicle inspection apparatus 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 side of the pellicle frame P in the height direction (Y direction) is adjusted by the adjustment mechanism 32 . At this time, the pellicle support portion 30 is located at the attachment position near the end of the surface plate 10 in the +X direction.

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.

After the pellicle frame P is moved to the inspection position, the inspection unit 20 inspects the pellicle film. In this embodiment, foreign matter such as dust adhering to the pellicle film is detected from an image captured by the camera 22 . Also, the tension measuring device 23 measures the tension applied to the pellicle film.

If it is detected that foreign matter such as dust adheres to the pellicle film, the foreign matter is removed by blowing a gas such as air from a nozzle (not shown) to the foreign matter. This nozzle may be shared with the air nozzle 231 of the tension measuring device 23 .

This inspection is first performed at the upper end position where the camera 22 is positioned near the upper end of the column 21 . The inspection unit 20 moves the guide member 33, that is, the pellicle frame P, by a predetermined distance in the -X direction. In this way, the pellicle membrane stretched over the pellicle frame P supported by the pellicle supporter 30 is sequentially inspected.

After the inspection is performed while moving the camera 22 and the tension measuring device 23 from the end in the −X direction to the end in the +X direction in this way, the inspection unit 20 moves the camera 22 and the tension measuring device 23 downward along the column 21. (-Y direction). Then, the inspection unit 20 similarly moves the guide member 33, that is, the pellicle frame P, in the +X direction to perform inspection.

By repeating such operations, the entire surface of the pellicle film stretched on the pellicle frame P can be inspected.

In the case of foreign matter inspection, since the inside of the clean room in which the inspection is performed has a downward flow, there is a high possibility that foreign matter that has been blown away will reattach to the lower side. For this reason, when performing a foreign matter inspection, the inspection is performed from top to bottom. When only measuring the tension applied to the pellicle film, the inspection may be performed from bottom to top.

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

The tension measuring device 23 injects compressed air from the air nozzle 231 to the pellicle film under tension. The tension measuring device 23 measures the displacement of the pellicle film in the orthogonal direction by the compressed air jetted from the air nozzle 231 using the first ultrasonic sensors 232 , 233 , 234 and 235 .

In addition, the tension measuring device 23 detects the displacement of the pellicle film in the orthogonal direction outside the region where the displacement occurs due to the compressed air injected from the air nozzle 231 on the pellicle film using the second ultrasonic sensors 332 , 333 , 334 and 335 . Measured by

The tension measuring device 23 calculates displacements of the pellicle membrane measured by the second ultrasonic sensors 332 , 333 , 334 and 335 from displacements of the pellicle membrane measured by the first ultrasonic sensors 232 , 233 , 234 and 235 . By subtracting, for example, the influence of displacement of the pellicle film caused by downflow in the clean room is eliminated, and only displacement of the pellicle film caused by compressed air injected from the air nozzle 231 is measured.

At this time, the controller 237 of the tension measuring device 23 detects the displacement of the pellicle film measured by the first ultrasonic sensor and the pellicle film measured by the second ultrasonic sensors 332, 333, 334, and 335. In determining the difference between the displacement and the displacement of the pellicle membrane measured by the second ultrasonic sensors 332, 333, 334, and 335, each of the displacements of the pellicle membrane is calculated according to the distance from the first ultrasonic sensor weighting. In addition to the distance, weighting according to the order of measurement may be added.

The control unit 237 obtains the weighted average of the displacements of the pellicle membrane weighted as described above, and regards the weighted average as the displacement of the pellicle membrane measured by the second ultrasonic sensors 332, 333, 334, and 335. . As a result, the control unit 237 converts the displacement of the pellicle membrane measured by the first ultrasonic sensor into the displacement of the pellicle membrane measured by the second ultrasonic sensors 332, 333, 334, and 335 as described above. By subtracting the displacement of the pellicle film obtained by the weighted average as in, it is possible to measure only the displacement of the pellicle film due to the air injected from the air nozzle 231, which is measured by the first ultrasonic sensor. can.

[Function and effect of the tension measuring device]
As described above, the tension measuring device according to the present embodiment is configured so that the air nozzle 231 is arranged concentrically around the air nozzle 231 for injecting compressed air to the pellicle film in parallel with the direction of tension in which the pellicle film is subjected to tension. At least one first ultrasonic sensor (four in this embodiment) is provided on a straight line passing through the center.

Accordingly, by measuring the change in the pellicle film when compressed air is injected onto the pellicle film, the tension of the pellicle film and the anisotropy of the tension can be measured in a non-contact manner.

Also, two first ultrasonic sensors are preferably provided on a straight line passing through the center of the air nozzle 231 in parallel with the direction of tension in which the pellicle film is subjected to tension on concentric circles centered on the air nozzle 231 with the air nozzle 231 interposed therebetween. .

As a result, changes in the pellicle film can be measured on both sides of the position where the compressed air is injected in the tension direction of the pellicle film, and the tension of the pellicle film and the anisotropy of the tension can be measured with high accuracy.

The control unit 237 causes the pellicle film to be pulsed with micro-pressure compressed air that does not damage the pellicle film.

As a result, it is possible to accurately measure the tension of the pellicle film and the anisotropy of the tension without damaging the pellicle film and suppressing the influence on sound waves.

In addition, the control unit 237 measures, as a half-return time, the time it takes for the pellicle film to return from the time when the pellicle film changes to the maximum after the injection of the compressed air to the half of the maximum amount of change, and measures the tension of the pellicle film based on this half-return time. do.

As a result, the influence of fluctuations in the injection pressure of the compressed air can be suppressed, and the tension of the pellicle film can be measured with high accuracy.

Further, the control unit 237 measures the amount of change 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 based on this amount of change.

As a result, it is possible to suppress the mutual influence of the directions in which the tension is applied, and accurately measure the anisotropy of the tension of the pellicle film.

Here, as shown in FIG. 9, the amount of deformation of the pellicle film Pf due to the compressed air injected from the air nozzle 231 increases as the location where the compressed air hits, that is, the position facing the center On of the air nozzle 231 is closer. . Therefore, the farther the pellicle film Pf is from the position facing the center On of the air nozzle 231, the less deformation or the less deformation occurs.

At a location where the pellicle film Pf is not deformed or at a location where the deformation is slight, even if an attempt is made to measure the amount of deformation with an ultrasonic sensor, the anisotropy of the tension of the pellicle film Pf will not occur. It is not possible to measure the amount of deformation that can be accurately measured.

In FIG. 9, if the deformation region suitable for measuring the amount of deformation that allows accurate measurement of the anisotropy of the tension of the pellicle film Pf is the region surrounded by the dotted line Df, then the anisotropy of the tension of the pellicle film Pf is In order to accurately measure the amount of deformation, it is desirable that the distance D1 between the center of the air nozzle 231 and the centers of the first ultrasonic sensors 232, 233, 234, and 235 is small. The overlap between the suitable deformation region Df of the film Pf and the region hit by the ultrasonic waves should be large.

The tension measuring device according to the present embodiment detects ultrasonic waves (transmission waves) output from the first ultrasonic sensors 232, 233, 234, and 235 and the pellicle film Pf (see FIG. 9) in the vicinity of the air nozzle 231. It has an inclined surface 242a that reflects the ultrasonic wave (reflected wave) reflected by .

Here, as shown in FIG. 9, a line passing through the centers of the first ultrasonic sensors 232, 233, 234, and 235 and perpendicular to the transmitting/receiving surface S of the ultrasonic sensors is defined as a 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 in the same manner as the ultrasonic wave.

As described above, the tension measuring device according to the present embodiment has a configuration in which the ultrasonic waves output from the first ultrasonic sensors 232, 233, 234, and 235 are reflected by the inclined surface 242a. and the center line Os described above can be reduced.

Therefore, the tension measuring device according to the present embodiment can bring the area hit by the ultrasonic wave closer to the position facing the center On of the air nozzle 231, and the suitable deformation area Df of the pellicle film Pf and the area hit by the ultrasonic wave overlap can be increased.

Thereby, the deformation of the pellicle film Pf, which can accurately measure the anisotropy of tension, can be measured by the first ultrasonic sensors 232, 233, 234, and 235. FIG. In other words, it is possible to measure the deformation at a location where the deformation that enables accurate measurement of the anisotropy of the tension of the pellicle film Pf is reliably generated. As a result, it is possible to measure the amount of deformation that can accurately measure the anisotropy of the tension of the pellicle film Pf.

In addition, in the tension measuring device according to the present embodiment, each inclined surface 242a is parallel to the tension direction in which the pellicle film Pf receives tension (tension) on concentric circles centered on the air nozzle 231 and passes through the center On of the air nozzle 231. It is on a straight line and provided 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, and 235 are installed with their transmitting/receiving surfaces S directed toward the respective inclined surfaces 242a so as to be able to receive the ultrasonic waves reflected by the respective inclined surfaces 242a.

As a result, the tension measuring device according to the present embodiment reflects ultrasonic waves by the inclined surface 242a, so that the first ultrasonic sensors 232, 233, 234, and 235 can be arranged at positions separated from the air nozzle 231. , the first ultrasonic sensors 232, 233, 234, and 235 are close to the position facing the center On of the air nozzle 231, and can measure the deformation of the pellicle film Pf that can accurately measure the tension anisotropy. .

Here, the first ultrasonic sensors 232, 233, 234, and 235 need to be sufficiently vibration-isolated in order to suppress the influence of reverberant waves, for example, and maintain the measurement accuracy. For this reason, it is necessary to provide an additional structure for vibration isolation around the ultrasonic sensor, and the structure around the ultrasonic sensor, including the ultrasonic sensor, tends to increase in size. As an additional structure for vibration isolation, for example, there is a structure in which a lead plate is wrapped around the first ultrasonic sensors 232, 233, 234, and 235, or a structure in which the support member 245 such as the sensor housing 245a is enlarged. mentioned.

As described above, the tension measuring device according to the present embodiment has a configuration in which the first ultrasonic sensors 232, 233, 234, and 235 are arranged at positions separated from the air nozzle 231 and the ultrasonic waves are reflected by the inclined surface 242a. , even if the structure around the ultrasonic sensor including the ultrasonic sensor is enlarged, the influence thereof can be avoided.

That is, 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. Therefore, it is possible to avoid the influence that the area hit by the ultrasonic wave moves 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.

In addition, the tension measuring device according to the present embodiment has support members 245 that support the first ultrasonic sensors 232, 233, 234, and 235, respectively. The angles of 232, 233, 234, and 235 with respect to the inclined surface 242a, specifically, the rotation angles in the pitch direction and the rotation angles in the yaw direction are adjustable.

Thereby, the tension measuring device according to the present embodiment can adjust the position of the pellicle film Pf on which the ultrasonic waves hit and the angle at which the ultrasonic waves hit the pellicle film Pf. Thereby, the positions and angles at which the first ultrasonic sensors 232, 233, 234, and 235 measure the deformation of the pellicle film Pf can be adjusted. If the position and angle of the ultrasonic wave with respect to the pellicle film Pf can be adjusted in this way, it is possible to find the positional relationship that maximizes the amplitude of the ultrasonic wave (reflected wave).

In this embodiment, as described above, the rotation angles of the first ultrasonic sensors 232, 233, 234, and 235 in the pitch direction and the yaw direction are adjustable. The sensor housing 245a or the bracket 245b may be configured to be movable in a direction orthogonal to the rotation axis of and intersecting the central axis Os. For example, the sensor housing 245a or the bracket 245b is 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.

Thereby, the adjustment of the rotation angles in the pitch direction and the yaw direction of the first ultrasonic sensors 232, 233, 234, and 235 and the adjustment of the position at which the central axis Os of the ultrasonic wave hits the pellicle film Pf can be performed independently. It can be carried out.

Further, the sensor housing 245a or the bracket 245b may be configured to be movable only in a direction orthogonal 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 at which the central axis Os of the ultrasonic wave hits the pellicle film Pf with a simple configuration.

Further, in the tension measuring device according to this embodiment, the device main body 242 has a hollow portion 242b that accommodates the air nozzle 231. As shown in FIG.

Thereby, the tension measuring device according to the present embodiment can prevent the compressed air jetted from the air nozzle 231 from interfering with the ultrasonic wave. This prevents the ultrasonic waves received by the first ultrasonic sensors 232 , 233 , 234 , and 235 from being affected by the compressed air jetted from the air nozzle 231 .

Next, in the tension measuring device according to this embodiment, the effect of providing the second ultrasonic sensors 332, 333, 334, and 335 will be described.

FIG. 10 is an example of temporal changes in the displacement of the pellicle film when measuring the displacement of the pellicle film when compressed air is injected at time t1 using only the first ultrasonic sensors 232, 233, 234, and 235. is a graph showing Note that the graph in FIG. 10 shows the measurement result of one of the first ultrasonic sensors 232 , 233 , 234 , 235 .

As shown in FIG. 10, the displacement of the pellicle film during a period T from time t0 to time t1 immediately after the injection of compressed air is the displacement caused by the compressed air. However, the pellicle film continues to be displaced even after time t1 when the injection of compressed air ends.

The displacement of the pellicle film after this time t1 is displacement caused by downflow in the clean room, for example. In this way, the pellicle film undergoes a non-negligible displacement in addition to the displacement caused by the compressed air. Therefore, it is considered that the displacement of the pellicle film during the period T described above also includes the displacement caused by the downflow. Therefore, to accurately measure the displacement of the pellicle membrane due to compressed air, it is preferable to eliminate the displacement caused by the aforementioned downflow.

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

Furthermore, in the tension measuring device according to the present embodiment, displacements of the pellicle membrane measured by the first ultrasonic sensors 232, 233, 234, and 235 are measured by the second ultrasonic sensors 332, 333, 334, and 335. Only the displacement of the pellicle film caused by the air injected from the air nozzle 231 is measured by subtracting the displacement of the pellicle film. As a result, the influence of displacement of the pellicle film caused by, for example, downflow in the clean room can be eliminated, and the displacement of the pellicle film caused by compressed air can be accurately measured.

In addition, in the tension measuring device according to the present embodiment, the length of the propagation path Path_1 of the ultrasonic waves of the first ultrasonic sensors 232, 233, 234, and 235 and the length of the ultrasonic waves of the second ultrasonic sensors 332, 333, 334, and The first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 are arranged so that the ultrasonic wave propagation path Path_2 is the same.

As a result, the tension measuring device according to the present embodiment does not need to add correction or the like due to the difference between the length of the propagation path Path_1 and the length of the propagation path Path_2, so the processing by the control unit 237 can be simplified.

Further, in the tension measuring device according to the present embodiment, the displacement of the pellicle membrane measured by the first ultrasonic sensor and the displacement of the pellicle membrane measured by the second ultrasonic sensors 332, 333, 334, and 335 In determining the difference between the displacement and the displacement, for each of the displacements of the pellicle membrane measured by the second ultrasonic sensors 332, 333, 334, and 335, A weighted average of the weighted displacements of the pellicle membrane is obtained, and the weighted average is regarded as the displacement of the pellicle membrane measured by the second ultrasonic sensors 332 , 333 , 334 , and 335 .

As a result, the tension measuring device according to the present embodiment can more accurately measure displacement of the pellicle membrane caused by, for example, downflow, which may vary depending on the arrangement of the first ultrasonic sensors 232, 233, 234, and 235. can do. Therefore, each of the first ultrasonic sensors 232, 233, 234, and 235 can more accurately measure the displacement of the pellicle film caused by the compressed air.

Note that the average value of the displacement of the pellicle membrane measured by the second ultrasonic sensors 332, 333, 334, and 335 may be measured as the displacement of the pellicle membrane caused by downflow, for example.

Further, in the present embodiment, changes in the pellicle film are measured by an ultrasonic sensor, but changes in the pellicle film may be measured by an optical displacement sensor or the like.

Further, in the present embodiment, air is injected onto the pellicle film, but other than air, such as nitrogen or argon, may be injected.

In addition, in the present embodiment, four second ultrasonic sensors are arranged, but three second ultrasonic sensors are arranged so that a line connecting these three second ultrasonic sensors forms an equilateral triangle. may be placed three second ultrasonic sensors at .

Further, in the present embodiment, the displacement of the pellicle film due to compressed air may be measured a plurality of times, and the average value of these measurements may be measured as the displacement of the pellicle film due to compressed air. In this case, the displacement of the pellicle film due to compressed air can be determined more accurately.

Further, in the present embodiment, the measurement by each of the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 is performed for a predetermined period of time. but not limited to this, for example, the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 measure independently of each other It is good also as possible composition. In this case, the measurement timings of the first ultrasonic sensors 232, 233, 234, 235 and the second ultrasonic sensors 332, 333, 334, 335 can be matched.

As the above-mentioned predetermined order, 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, Examples include the second ultrasonic sensor 333, the second ultrasonic sensor 334, the second ultrasonic sensor 335, etc., but the order is not limited to this, and can be set in any order through experiments or the like. 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.

Although embodiments of the present invention have been disclosed, it will be apparent that modifications may be made by those skilled in the art without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 pellicle inspection device 23 tension measurement device 231 air nozzle (nozzle)
232, 233, 234, 235 1st ultrasonic sensor 332, 333, 334, 335 2nd ultrasonic sensor 236 compressed air injection part 237 control part 240 support base 241 support 242 device main body (tilt member)
242a Inclined surface (reflective portion)
242b hollow portion 245 support member 245a sensor housing 245b bracket 245c shaft member 245d shaft member 245e fixing member 300 frame member 340 sensor housing 340a surface S transmission/reception surface (reception surface)
Path_1 Ultrasonic wave propagation path of the first ultrasonic sensor Path_2 Ultrasonic wave propagation path of the second ultrasonic sensor R Area where displacement occurs due to injected compressed air

Claims (12)

a nozzle for injecting gas onto the pellicle film to which a predetermined tension is applied;
At least one is provided on a straight line passing through the center of the nozzle in parallel with the tension direction, which is the direction in which the pellicle film is subjected to the tension, on concentric circles centered on the nozzle, and is caused by the gas injected from the nozzle. , a first ultrasonic sensor that measures the displacement of the pellicle membrane in an orthogonal direction orthogonal to the tension direction;
a plurality of second ultrasonic sensors for measuring the displacement of the pellicle film in the orthogonal direction outside the region where displacement occurs due to the gas injected from the nozzle on the pellicle film;
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. A tension measuring device comprising a controller that measures the 2. The tension measuring device according to claim 1, wherein two of said first ultrasonic sensors are provided on a straight line parallel to said tension direction and passing through the center of said nozzle on concentric circles centered on said nozzle with said nozzle interposed therebetween. . 3. The tension measuring device according to claim 1, wherein the controller injects the gas at a predetermined minute pressure in a pulsed manner to the pellicle film. The control unit measures the time required for the pellicle film to return from the time when the pellicle film is displaced to the maximum after the injection of the gas to the half of the maximum displacement as a half-return time, and the pellicle film is applied to the pellicle film based on the half-return time. 4. The tension measuring device according to any one of claims 1 to 3, wherein the tension is measured. The pellicle film receives the tension in a plurality of directions, and at least one first ultrasonic sensor is provided on a straight line passing through the center of the nozzle in parallel to the tension direction in each of the plurality of directions. be
The controller measures a maximum amount of change when the pellicle film is displaced to a maximum after the gas is injected, and measures anisotropy of the plurality of tensions applied to the pellicle film based on the maximum amount of change. 5. The tension measuring device according to any one of claims 1 to 4, which measures tension. further comprising a reflector that reflects ultrasonic waves in the vicinity of the nozzle,
The tension measuring device according to any one of claims 1 to 5, wherein the first ultrasonic sensor is arranged at a position more distant from the nozzle than the reflecting section. further comprising an inclined member having an inclined surface on the straight line and between the first ultrasonic sensor and the center of the nozzle, the inclined surface being inclined with respect to the jetting direction of the gas jetted from the nozzle;
The reflecting portion is configured by the inclined surface,
7. The tension measuring device according to claim 6, wherein said first ultrasonic sensor is installed with a receiving surface facing said inclined surface so as to be able to receive ultrasonic waves reflected by said inclined surface. further comprising a support member that supports the first ultrasonic sensor,
8. The tension measuring device according to claim 6, wherein the supporting member is configured to be able to adjust an angle of the first ultrasonic sensor with respect to the reflecting section. 8. The tension measuring device according to claim 7, wherein the inclined member has a hollow portion that accommodates the nozzle. The first ultrasonic sensor and the first ultrasonic sensor such that the length of the ultrasonic propagation path of the first ultrasonic sensor and the length of the ultrasonic propagation path of the second ultrasonic sensor are the same. 10. The tension measuring device according to any one of claims 1 to 9, wherein two ultrasonic sensors are arranged. The first ultrasonic sensor is provided four concentrically around the nozzle,
The second ultrasonic sensor is provided on four concentric circles different from the first ultrasonic sensor around the nozzle,
The first ultrasonic sensor and the second ultrasonic sensor are alternately arranged in a circumferential direction around the nozzle,
When obtaining a difference between the displacement of the pellicle membrane measured by one of the first ultrasonic sensors and the displacement of the pellicle membrane measured by the second ultrasonic sensor, the control unit performs the 4 each of the displacements of the pellicle membrane measured by the two second ultrasonic sensors is weighted according to the distance from the one first ultrasonic sensor, and the weighted displacement of the pellicle membrane is 11. The tension measurement according to any one of claims 1 to 10, wherein a weighted average is obtained, and the weighted average is regarded as the displacement of the pellicle membrane measured by the second ultrasonic sensor. Device. injecting a gas from a nozzle onto the pellicle membrane under predetermined tension;
Displacement of the pellicle film in a direction orthogonal to the direction of tension, which is the direction in which the pellicle film is subjected to the tension, by the gas injected from the nozzle is measured on a concentric circle centered on the nozzle in the direction of tension. measuring with at least one first ultrasonic sensor provided on a straight line parallel to and passing through the center of the nozzle;
a step of measuring displacement of the pellicle film in the orthogonal direction on the pellicle film outside a region where displacement occurs due to the gas injected from the nozzle, using a plurality of second ultrasonic sensors;
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. and measuring the tension.

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