TWI807162B - Mask inspection device - Google Patents

Abstract

The present invention can prevent the resonance of the reflector and prevent the occurrence of suspected defects. The holding member provided on the side of the substantially frame-shaped frame that holds the photomask to be inspected in the substantially vertical direction has: a hollow rod-shaped member extending in the horizontal direction; a first mounting portion for mounting the rod-shaped member to the frame; and a second mounting portion provided with a reflector. In order to make the frame move horizontally along the upper surface of the platform, a hollow rod-shaped member is extended along the horizontal direction. A light irradiation part is provided on the pillar installed on the platform, and is arranged at substantially the same height as the reflector, and irradiates light in a substantially horizontal direction toward the reflector.

Description

Mask inspection device

The invention relates to a photomask inspection device.

Patent Document 1 discloses a frame position detection mechanism in a photomask inspection device. In this photomask inspection device, a column is provided on a stage, an irradiation unit is provided on the column, and a reflector is provided on a holding member protruding in a horizontal direction from a side surface of a frame holding a photomask. The position of the frame is detected based on light irradiated from the irradiating portion and reflected by the reflector.

[Prior Art Literature]

[Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-26404

In the photomask inspection apparatus, since the frame moves, it is necessary for the holding member holding the reflector to protrude in the horizontal direction from the side surface of the frame. However, since the resonance frequency of the holding member described in Patent Document 1 is low, the holding member resonates due to various vibrations in the factory. As a result, the reflector vibrated, causing a suspected defect when inspected.

This invention was made in view of such a situation, and it aims at providing the mask inspection apparatus which can prevent the resonance of a reflector and the generation|occurrence|production of a pseudo-defect.

In order to solve the above problems, the photomask inspection apparatus of the present invention is characterized by, for example, comprising: a platform; a substantially frame-shaped frame that holds a photomask to be inspected; a moving unit that horizontally moves the above-mentioned frame along the upper surface of the above-mentioned platform; a holding member that is provided on a side surface of the above-mentioned frame; a reflector that is provided at the front end of the above-mentioned holding member; A hollow rod-shaped member extending along the horizontal direction; a first mounting part disposed on a first end of the rod-shaped member for mounting the rod-shaped member on the frame; and a second mounting part disposed on a second end of the rod-shaped member opposite to the first end, and the reflector is disposed on the second mounting part.

According to the photomask inspection apparatus of the present invention, the holding member provided on the side of the substantially frame-shaped frame that holds the photomask to be inspected substantially in the vertical direction includes: a hollow rod-shaped member extending in the horizontal direction; a first mounting portion for mounting the rod-shaped member to the frame; and a second mounting portion provided with a reflector. In order to make the frame move horizontally along the upper surface of the platform, a hollow rod-shaped member is extended along the horizontal direction. A light irradiation part is provided on the pillar installed on the platform, and is arranged at substantially the same height as the reflector, and irradiates light in a substantially horizontal direction toward the reflector. By using a hollow rod-shaped member as the holding member for the reflector, the holding member can be lightened to prevent resonance of the reflector, thereby preventing the occurrence of suspected defects caused by it.

Here, the thickness of the rod-shaped member may be greater than or equal to the thickness of the frame. Thereby, bending of the rod-shaped member can be prevented.

Here, the rod-shaped member may be a hollow round rod, and the thickness of the rod-shaped member may be approximately 1/40 to approximately 1/50 of the diameter of the rod-shaped member. Thereby, the rod-shaped member can be lightened and strengthened.

Here, the rod-shaped member may be formed of fiber-reinforced plastic. Thereby, the weight of the rod-shaped member can be reduced, and the rigidity can be improved.

Here, the direction of the fibers contained in the above-mentioned rod-shaped member can be relative to the direction of the above-mentioned rod-shaped member. Axes are tilted. Thereby, expansion and contraction of the rod-shaped member and position change of the reflector can be prevented.

Here, the moving part may be horizontally moved between a loading position where the photomask is mounted on the frame and an inspection position where the photomask is inspected, and the length of the rod-shaped member is greater than or equal to the distance in the horizontal direction between the first mounting part and the light irradiation part when the frame is located at the loading position. Thereby, when the frame is located at the loading position and when the frame is moved in the horizontal direction, collision between the reflector and the irradiating part can be avoided.

According to the present invention, the resonance of the reflector can be prevented to prevent the generation of pseudo-defects.

1: Mask inspection device

10: Platform

10a: Lower surface

10b, 10c: concave part

10d: bearing surface

10e: upper surface

10f: Slot

10g, 10h, 10i: side

20: Shooting Department

21: column

22, 22a, 22b: camera

23: air cushion

25: Position detection unit

26a, 26b: irradiation part

30: Mobile Department

31: Mobile component body

32, 33: side air cushion

34: Air cushion below

35: convex part

40: Mask holding part

41: frame

41a: claw

41c: hole

41d: Lower frame part

41f: holding part

42: Adjustment mechanism

42a: the first block

42b: The second block

43:Rotary mechanism

51, 52: Devibration table

53: light source

54: Light guide member

61a, 62a: Movers

62b: Stator

65: frame

66: Board

70: Keeping components

70a, 70a': rod-shaped member

70b: The first installation part

70c: The second installation part

70d, 70e: plate-shaped part

71a, 71b: reflectors

73: Board

141: Input and output device

142: Network

143: memory media

151: CPU

151a: Control Department

152: RAM

153:ROM

154: Input and output interface

155: communication interface

156:Media interface

231: light source

232: beam splitter

233: reflector

234: detector

341: air cushion below

342: air cushion below

431:Rotary drive unit

431a: output shaft

432A: 1st screw member

432B: Second screw member

433A: 1st nut member

433B: The second nut member

434, 434a, 435, 436: sprockets

437, 437a, 437b: power transmission part

438A: Pin 1

438B: 2nd pin

439A: 1st bearing

439B: 2nd bearing

701: Plane Department

702: screw hole

703: round hole

704: screw hole

705: long hole

706: hole

707: back

710, 720: holding member

710a, 720a: reflector mounting plate

[FIG. 1] It is a perspective view which shows the outline of the photomask inspection apparatus 1 of 1st Embodiment.

[ FIG. 2 ] is a schematic front view showing the photomask inspection apparatus 1 .

[ FIG. 3 ] is a diagram showing the outline of the moving unit 30 .

[FIG. 4] is a figure which shows the outline|summary of the mask holding|maintenance part 40, especially the frame 41, and the rotation mechanism 43.

[ FIG. 5 ] is a plan view schematically showing a photomask inspection device 1 .

[ FIG. 6 ] is a diagram showing the measurement principle of the position detection unit 25 .

[ FIG. 7 ] is a diagram schematically showing a holding member 70 and a method of mounting the holding member 70 on the frame 41 .

[FIG. 8] It is a schematic diagram when the rod-shaped member 70a was formed using carbon FRP.

[FIG. 9] It is a schematic diagram of the rod-shaped member 70a' of a modification.

[ FIG. 10 ] is a block diagram showing the electrical configuration of the photomask inspection apparatus 1 .

[ Fig. 11 ] is an example of a relatively heavy holding member 710 made of a metal base.

[ FIG. 12 ] is a diagram showing the vibration of the holding member 710 at 24 Hz, and (A) shows that it is installed on the frame 41 Vibration of the reflector mounting plate 710 a in the end side holding member 710 , (B) shows the vibration of the reflector mounting plate 710 a provided in the end side holding member 710 under the frame 41 .

[FIG. 13] It is an example of a holding member 720 in which three rods made of ultra-indium steel with a diameter of about 10 mm are arranged and reinforced with a plate-shaped member.

[ FIG. 14 ] is a diagram showing the vibration of the holding member 720 at 180 Hz, (A) shows the vibration of the reflector mounting plate 720a in the holding member 720 provided on the upper end side of the frame 41, and (B) shows the vibration of the reflector mounting plate 720a in the holding member 720 provided on the lower end side of the frame 41.

[ FIG. 15 ] is a diagram showing the vibration of 12.5 Hz when the holding member 70 of this embodiment is used, (A) shows the vibration of the plate-shaped part 70e in the holding member 70 provided on the upper end side of the frame 41, and (B) shows the vibration of the plate-shaped part 70e in the holding member 70 provided on the lower end side of the frame 41.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The inspection apparatus of the present invention holds the photomask M to be inspected substantially in the vertical direction, moves a camera etc. in the substantially vertical direction, and inspects the defect of the pattern formed on the photomask M.

In the present embodiment, the mask M to be inspected is, for example, a mask for exposure used for manufacturing a substrate for a display device of an organic EL or a liquid crystal display device. The photomask M is one or a plurality of transfer patterns for imaging equipment formed on a large substantially rectangular substrate having a side of about 1 m. This embodiment is particularly suitable for the inspection of the mask M for an organic EL display that forms a high-density pattern and requires high-sensitivity inspection.

FIG. 1 is a perspective view schematically showing a photomask inspection apparatus 1 according to a first embodiment. FIG. 2 is a schematic front view of the photomask inspection apparatus 1 . In this specification, the direction substantially along the longitudinal direction of the platform 10 (detailed below) is defined as the x direction, the vertical direction is defined as the y direction, and the direction perpendicular to the x and y directions is defined as the z direction. Furthermore, in FIGS. 1 and 2 , a part is omitted for explanation. Composition icon.

The mask inspection apparatus 1 mainly includes a table 10 , an imaging unit 20 , a column 21 , a position detection unit 25 , a moving unit 30 , a mask holding unit 40 , and vibration-removing tables 51 and 52 .

The platform 10 is configured as a stage, and is supported on vibration-isolating tables 51 and 52 provided at a plurality of places (six places) on the installation surface F. As shown in FIG.

The platform 10 is a roughly rectangular parallelepiped (slab-shaped) stone member with a width W of about 4500 mm, a depth D of about 1200 mm, and a thickness T of about 400 mm. The platform 10 has a lower surface 10a and an upper surface 10e parallel to the lower surface 10a.

Columns 21 are provided on the upper surface 10e of the platform 10 so as to protrude upward (+y direction) from the upper surface 10e. The column 21 is formed of ceramics or the like. In order to lower the center of gravity G, the column 21 is preferably hollow.

On the lower surface 10a of the platform 10, recessed portions 10b, 10c having a substantially cubic shape are formed. One recess 10b is formed at each of the four corners of the lower surface 10a. The recesses 10c are formed one by one along the long sides of the lower surface 10a, and two in total are formed. In order to maintain the strength of the platform 10 , the depth D1 of the recesses 10 b and 10 c is set to be 0.3 to 0.5 times the thickness T of the platform 10 . In addition, the depth D1 of the recesses 10b, 10c, that is, the height of the support surface 10d is set so that the angle θ (see FIG. 2 ) of the center of gravity G of the entire mask inspection apparatus 1 looking up from the support surface 10d becomes as small as possible (for example, approximately 30 degrees) below 60 degrees.

The vibration-isolating table 51 mounted on the installation surface F is provided inside the recessed part 10b. The vibration-isolating table 52 mounted on the installation surface F is provided inside the recessed part 10c. The vibration-removing platform 51 is an active vibration-removing platform, and the vibration-removing platform 52 is a passive vibration-removing platform supporting weight. The vibration-isolating tables 51 and 52 are well known, and thus description thereof will be omitted.

The height of the devibration tables 51, 52 is higher than the depth D1 of the recesses 10b, 10c. Therefore, the support surface 10d is supported by the vibration-isolating tables 51 and 52 , and the platform 10 is placed on the installation surface F via the vibration-isolating tables 51 and 52 . Thereby, the center of gravity G of the photomask inspection apparatus 1 can be lowered based on 10 d of supporting surfaces.

A groove 10f is formed on the upper surface 10e of the platform 10 (the upper surface 10e includes the groove 10f). The groove 10f is a guide for moving the moving part 30 . In order to improve the strength of the platform 10, the groove 10f extends along the length of the platform 10. In the (x direction) direction, it is formed at a position that does not overlap with the recesses 10b, 10c in plan view (when viewed from the +y direction).

The depth D2 of the groove 10 f is substantially smaller than the thickness T of the platform 10 . Also, the depth D2 of the groove 10f is set such that the optical axis ax (see FIG. 2 ) of the camera 22 when the camera 22a (described in detail below) abuts on the upper surface 10e coincides with the lower end of the mask M supported by the moving part 30 (detailed in detail below), so that the center of gravity G becomes the lowest. In this embodiment, the depth D2 of the groove 10f is about 60 mm. Therefore, even if the groove 10f is formed, the rigidity of the table 10 can be set to a sufficiently high state.

The imaging unit 20 mainly includes a camera 22 (refer to FIG. 2 ) installed on a column 21 . The camera 22 is, for example, a CCD camera or a TDI camera as a special CCD camera, and has two cameras 22a and 22b. The cameras 22a and 22b respectively have an objective lens for converting g-rays and e-rays into parallel light, an optical component for separating g-rays and e-rays passing through the objective lens (for example, a component that functions as a polarizing beam splitter and a bidirectional color filter), two sets of imaging lenses for separately imaging the g-rays and e-rays separated by the optical components, and an imaging element for separately imaging the g-rays and e-rays imaged by the two sets of imaging lenses to simultaneously image transmitted light and reflected light. Furthermore, the cameras 22a and 22b can use known techniques, so detailed descriptions are omitted.

Two cameras 22a and 22b are provided adjacent to each other along the y direction. A moving mechanism (not shown) including an air cushion 23 (see FIG. 5 ) is provided between the camera 22 and the column 21 . A camera 22 is installed on this moving mechanism so that the optical axis ax is parallel to the z axis.

The camera 22 moves in the vertical direction (y direction) by a moving mechanism not shown in the figure (y direction). The moving mechanism moves the two cameras 22a, 22b along the post 21 between the initial position where the camera 22a abuts against the upper surface 10e of the platform 10 and the upper position where the camera 22b is near the upper end of the post 21 (refer to the 2-point locking line in FIG. 2 ).

In addition, the imaging unit 20 has a transmission illumination light source and a reflection illumination light source which are not shown. The transmission illumination light source is installed on the back side (-z side) of the mask M, and irradiates so-called g-rays (for example, light with a wavelength of 435.84 [nm]). The reflective illumination light source is set on the surface side (+z side) of the mask M to irradiate the so-called e-ray Line (such as light with a wavelength of 546.07 [nm]). The camera 22 simultaneously receives the g-rays irradiated from the transmitted illumination light source and the e-rays irradiated from the reflected illumination light source to form an image. Thereby, the image obtained by the camera 22 is compared with the pattern information (detailed details below), whereby the inspection of the mask M is performed.

When two cameras 22a, 22b are used, the cameras 22a, 22b are used to photograph the lower half and the upper half of the inspection area of the mask M respectively, and the photographed data and pattern information are compared, thereby obtaining twice the efficiency compared with the case of using one camera. Therefore, the camera 22 preferably has two cameras 22a, 22b. However, the number of cameras 22 is not limited to two, and may be one (one of cameras 22a, 22b).

The position detection unit 25 is a laser interferometer (for example, a linear interferometer), and mainly includes the irradiation units 26a, 26b provided on the column 21 and the reflectors 71a, 71b provided on the holding member 70 (detailed below).

The irradiation units 26 a and 26 b are provided on the column 21 . Light irradiated from light source 53 (see FIG. 1 ) is guided to irradiation portions 26 a and 26 b via light guide member 54 (see FIG. 1 ) and the like. The irradiating parts 26a, 26b are arranged at approximately the same height as the reflectors 71a, 71b, respectively. The irradiation unit 26a irradiates the extracted light toward the reflector 71a in a substantially horizontal direction. Moreover, the irradiation part 26b irradiates the extracted light toward the reflector 71b in a substantially horizontal direction.

The reflectors 71a and 71b are mirrors for returning light to the incident direction (returning light beams), for example, retroreflectors. The reflectors 71a, 71b are used to detect the x-direction position of the frame 41 (detailed below). The reflectors 71a, 71b are respectively provided at the front end of the holding member 70 . Also, the reflector 71 a is provided near the lower end of the frame 41 , and the reflector 71 b is provided near the upper end of the frame 41 .

The moving part 30 is mounted on the stage 10, and the mask holding|maintenance part 40 containing the frame 41 which holds the mask M is mounted. FIG. 3 is a diagram showing the outline of the moving unit 30 . The moving unit 30 mainly includes a moving member body 31 , side air pads 32 , 33 , lower air pads 34 ( 341 , 342 ), and a convex portion 35 .

The moving member body 31 is a bar-shaped member on which the mask holding portion 40 is provided. The moving member body 31 is formed of aluminum for weight reduction. On the side of the moving member body 31, a side air cushion 32, 33. The front end surface of the side air cushion 32 faces the side surface 10g of the groove 10f, and the front end surface of the side air cushion 33 faces the side surface 10h of the groove 10f.

A thin air layer is formed between the side surface 10g and the front end surface of the side air cushion 32 and between the side surface 10h and the front end surface of the side air cushion 33, and the side air cushions 32 and 33 expand the side surfaces of the groove 10f through the air layer. Since the platform 10 is made of stone and the size of the groove 10f does not change, the side air cushions 32, 33, that is, the moving part 30 are guided by the groove 10f.

A lower air cushion 34 is provided on the lower side of the moving member body 31 . The lower air pad 34 is a substantially rectangular-shaped member in a plan view (viewed from above (+y direction)), and has a lower air pad 341 provided at the +x side end of the moving member body 31 and a lower air pad 342 provided at one end of the moving member body 31.

If the air is ejected from the openings on the lower surface side of the lower air pads 341, 342 toward the bottom surface 10i, a thinner air layer is formed between the bottom surface 10i and the lower air pads 341, 342 by the ejected air, and the lower air pads 341, 342 float from the bottom of the groove 10f.

A convex portion 35 is provided on the upper side of the moving member body 31 . The convex portion 35 is a plate-shaped member, and a first bearing 439A or a second bearing 439B is provided inside (not shown in FIG. 3 , see FIG. 4 ).

Return to the description of Figures 1 and 2. The photomask inspection apparatus 1 has a lower linear motor that moves the moving part 30 along the groove 10f (or upper surface 10e ) of the stage 10 , and an upper linear motor that is driven to follow the lower linear motor. The mover 61a of the lower linear motor (refer to FIG. 2 ) is provided on the moving member body 31 , and the mover 62a of the upper linear motor (refer to FIGS. 1 and 2 ) is provided on the upper side of the frame 41 . The stator (not shown) of the lower linear motor is installed on the platform 10, and the stator 62b (see FIG. 2) of the upper linear motor is installed on the frame 65 (see FIG. 2).

A moving mechanism (not shown) for moving positions in the horizontal direction (x direction) and vertical direction (y direction) is provided on the movable member 62a. This moving mechanism changes the position of the movable member 62a in the horizontal direction (x direction) along with the rotation of the frame 41 (details will be described later), thereby preventing the phase deviation of the upper linear motor.

The mask holding unit 40 mainly includes a frame 41 , an adjustment mechanism 42 (not shown in FIG. 2 ) for changing the position of the lower side of the mask M in the height direction (y direction), and a rotation mechanism 43 for rotating the frame 41 .

The frame 41 is formed in a substantially frame shape so as to surround the outer periphery of the mask M held vertically. In this embodiment, a plurality of square rods are combined to form a substantially frame-shaped frame 41 . The frame 41 is a reference frame used as a reference for position detection and the like. The frame 41 holds the photomask M so that the surface (pattern-formed surface) of the photomask M may be parallel to the xy plane. A plurality of claws 41a (not shown in FIG. 2 ) for holding the photomask M are provided on the frame 41 .

A holding portion 41 f is provided on the upper side of the frame 41 . The holding part 41f is an air cushion, for example, and sandwiches the thin-plate-shaped plate part 66 (refer FIG. 2) provided in the frame 65 (refer FIG. 2). Thereby, the frame 41 is supported so that the x-axis of the frame 41 does not deviate from the center.

A holding member 70 is provided on a side surface of the frame 41 so as to protrude in the lateral direction (x direction). One of the holding members 70 is provided at a higher position on the upper end side of the frame 41 , and the other holding member 70 is provided at a lower position on the lower end side of the frame 41 . The holding member 70 will be described in detail below.

An adjustment mechanism 42 and a rotation mechanism 43 are provided below the frame 41 . The adjustment mechanism 42 is formed in plural along the x direction. The adjustment mechanism 42 has a first block 42a whose upper surface is inclined relative to the xz plane, and a second block 42b whose lower surface is inclined relative to the xz plane. The height is adjusted by changing the relative positional relationship between the first block 42a and the second block 42b. Since the adjustment mechanism 42 is known, detailed description is omitted.

The rotation mechanism 43 is provided near both ends of the frame portion located on the lower side of the frame 41 . FIG. 4 is a diagram showing the outline of the mask holding unit 40 , especially the frame 41 and the rotation mechanism 43 . In FIG. 4 , illustration of the claw portion 41 a and the adjustment mechanism 42 is omitted.

The rotating mechanism 43 mainly has the rotating driver 431, the first screw component 432A and the 2nd screw component 432B, the 1st nut component 433A and the 2rd nuts 433B, the sprocket 434, 435, 436, the power conduction department 437 (437A, 437B), and the first sales 438A and the 2nd. Sell 438B, and the first bearing 439A and the 2nd bearing 439B.

The first nut member 433A and the second nut member 433B are provided near both ends of the lower frame portion 41d and embedded in the bottom portion of the lower frame portion 41d located on the lower side of the frame 41 . The first screw member 432A is screwed to the first nut member 433A, and the central axis thereof substantially coincides with the central axes of the first pin 438A and the first bearing 439A. The second screw member 432B is screwed to the second nut member 433B, and its central axis substantially coincides with the central axes of the second pin 438B and the second bearing 439B.

The first pin 438A and the second pin 438B are rod-shaped members having a substantially hemispherical surface at the bottom, are supported by the lower air pads 341 , 342 , and can swing relative to the lower air pads 341 , 342 . A first bearing 439A and a second bearing 439B are respectively provided at positions where the central axis on the upper surface side of the moving member body 31 substantially coincides with the first pin 438A and the second pin 438B. The lower end of the first screw member 432A is supported by the first bearing 439A, and the lower end of the second screw member 432B is supported by the second bearing 439B.

The load of the mask holding part 40 or the mask M is supported by the rigid stage 10 through the first pin 438A and the second pin 438B with the highest rigidity or the air cushions 341 and 342 below. In addition, since the lower air cushions 341 and 342 are provided near both ends of the moving member body 31, the load of the mask holder 40 and the like can be stably supported.

The rotation drive part 431 is an actuator, such as an electric motor, and has an output shaft 431a. The sprocket 434 is integrated with the output shaft 431a. Also, the sprocket 434a and the sprocket 435 are integrated with the first screw member 432A, and the sprocket 436 is integrated with the second screw member 432B by press fitting or the like. The sprocket 434 and the sprocket 434a are connected by the power transmission part 437a, and the sprocket 435 and the sprocket 436 are connected by the power transmission part 437b.

If the distance (distance in the x direction) between the reflector 71a and the second screw member 432B in plan view is set as distance A, and the distance in plan view (distance in x direction) between the reflector 71a and the first screw member 432A is set as distance B, then the number of teeth α of the sprocket 435 and the number of teeth β of the sprocket 436 have the relationship of the number of teeth α:the number of teeth β=distance A:distance B. That is, the ratio of the amount of movement in the y direction of the first screw member 432A to the amount of movement in the y direction of the second screw member 432B is inversely proportional to the distance from the reflector 71 a.

When the rotation driving part 431 is driven, the output shaft 431a and the sprocket 434 rotate, and the power transmission The portion 437a rotates the sprocket 435, and the power transmission portion 437b rotates the sprocket 436. The first screw member 432A rotates together with the rotation of the sprocket 435 , and the second screw member 432B rotates together with the rotation of the sprocket 436 . Since the number of teeth β of the sprocket 436 is greater than the number of teeth α of the sprocket 435, the first screw member 432A into which the sprocket 435 is pressed rotates more than the second screw member 432B into which the sprocket 436 is pressed. Therefore, the amount of movement in the y direction of the first screw member 432A is greater than the amount of movement in the y direction of the second screw member 432B. Thereby, the frame 41 rotates.

Especially in this embodiment, since the number of teeth α: the number of teeth β=distance A: distance B, the frame 41 is rotated in an arc-drawing manner based on the position O in the x direction of the reflector 71a to avoid movement of the position O (refer to the arrow in FIG. 4 ). Here, the position O is a position where a substantially parallel line connecting the sprockets 435 and 436 intersects a substantially vertical line including the reflector 71a. In addition, the amount of movement in the y direction at the position of the first screw member 432A when the frame 41 is rotated to the maximum is about ±3 mm.

Assuming that the rotation angle of the frame 41 is Ψ, the reflectors 71a and 71b move in the height direction (y direction) by an amount of H1×cosΨ. However, since the angle Ψ is small, cosΨ is approximately 1, and the positions of the reflectors 71a and 71b in the height direction hardly change. Therefore, no abnormality occurs in the position detection of the frame 41 using the reflectors 71a, 71b.

Next, the position detection unit 25 and the holding member 70 of the frame 41 will be described. As shown in FIGS. 1 and 2 , light is irradiated from the irradiation section 26 a to the reflector 71 a, and light is irradiated from the irradiation section 26 b to the reflector 71 b. The position detection of the frame 41 is performed mainly using the irradiation part 26a and the reflector 71a. The illuminating part 26b and the reflector 71b are auxiliary used for correcting errors due to the pitching of the platform 10 caused by the warping of the platform 10 during the movement of the frame 41 .

FIG. 5 is a schematic plan view showing the photomask inspection apparatus 1 . The frame 41 and the holding member 70 are provided so as to be movable between the loading position (see the dotted line in FIG. 5 ) where the mask M near the end of the platform 10 in the +x direction is loaded on the frame 41 and the inspection position (see the solid line in FIG. 5 ) where the mask M is inspected. The loading position is near the +x end of the platform 10, and the photomask M is prevented from colliding with the column 21 and the imaging unit 20 during loading.

The light irradiated from the irradiation parts 26a and 26b is reflected by the reflectors 71a and 71b and returns to the irradiation parts 26a and 26b, whereby the position detection part 25 performs position measurement. In order to perform the inspection process, it is necessary to measure the position of the mask M when the frame 41 (mask M) is located at the loading position. Therefore, when the frame 41 is at the loading position, it is necessary to extend the holding member 70 in the horizontal direction so that the reflectors 71a, 71b are located on the column 21, that is, closer to the -x direction than the irradiation portions 26a, 26b. In addition, the length of the holding member 70 (here, the rod-shaped member 70a (described in detail below)) must be greater than or equal to the distance L1 (see FIG. 5 ) in the horizontal direction between the first mounting portion 70b (detailed in detail below) and the irradiating portions 26a, 26b when the frame 41 is located at the loading position (refer to the dotted line in FIG. 5 ).

FIG. 6 is a diagram showing the measurement principle of the position detection unit 25 . The irradiation units 26 a and 26 b mainly include a light source 231 , a beam splitter 232 , a reflector 233 , and a detector 234 . The light source 231 is irradiated with orthogonal dual-frequency laser light waves (light waves of frequency f1 and frequency f2), the light of wavelength f1 is reflected by the beam splitter 232 and reflected by the reflector 233, and the light of wavelength f2 is transmitted through the beam splitter 232 and then reflected by the reflectors 71a and 71b. Such light is incident on detector 234 . The distance between the illuminating parts 26a, 26b and the reflectors 71a, 71b, that is, the positions of the frame 41 and the mask in the x direction is calculated according to the phase change of the light beat (measurement signal) received by the detector 234. This operation is performed by comparing the phase of the reference signal (f1-f2) before being incident on the beam splitter 232 with the phase of the measurement signal.

FIG. 7 is a diagram schematically showing a holding member 70 and a method of installing the holding member 70 on the frame 41 . The holding member 70 mainly includes a rod-shaped member 70a, a first mounting portion 70b, and a second mounting portion 70c.

The rod-shaped member 70a is a hollow rod-shaped member extended along the horizontal direction. A first attachment portion 70b for attaching the rod-shaped member 70a to the frame 41 is provided at one end of the rod-shaped member 70a. The first mounting portion 70b is formed of the same material as the frame 41 (for example, metal such as iron). The first mounting portion 70b is fixed to the rod-shaped member 70a by inserting a part of the round rod-shaped member into the hollow portion of the rod-shaped member 70a and sticking it. The amount to insert the first mounting portion 70b into the rod-shaped member 70a may be about 20 mm.

The first mounting portion 70 b forms a plane portion 701 abutting against the frame 41 . Make the flat part 701 abut against On the back side of the frame 41, the frame 41 and the first mounting portion 70b are screwed together with cap screws or the like through the hole 41c formed in the frame 41 and the screw hole 702 formed in the first mounting portion 70b, whereby the holding member 70 is mounted on the frame 41.

The second attachment portion 70c is provided at the end of the rod-shaped member 70a where the first attachment portion 70b is not provided. The 2nd attachment part 70c has the plate-shaped part 70d attached to the rod-shaped member 70a, and the plate-shaped part 70e attached to the plate-shaped part 70d. The plate-shaped parts 70d and 70e are formed using the same material as the rod-shaped member 70a (here, carbon FRP).

A round hole 703 is formed in the plate-like portion 70d. The plate-shaped portion 70d is fixed to the rod-shaped member 70a by inserting the rod-shaped member 70a into the circular hole 703 and sticking it. The plate-shaped portion 70d is as light as possible by making a hole in the plate-shaped portion 70d and inserting the plate-shaped portion 70d. The plate-shaped portion 70d and the plate-shaped portion 70e are brought into contact, and the plate-shaped portion 70d and the plate-shaped portion 70e are screwed together with cap screws or the like through the screw holes 704 formed in the plate-shaped portion 70d and the long holes 705 formed in the plate-shaped portion 70e, thereby fixing the plate-shaped portion 70d and the plate-shaped portion 70e.

The reflectors 71a and 71b (not shown in FIG. 7 ) are provided on the plate-like portion 70e. The reflectors 71a and 71b are fixed to the back surface 707 of the plate-like portion 70e so as to cover the hole 706 . Since the long hole 705 is formed in the plate-shaped portion 70e, the relative positional relationship between the plate-shaped portion 70d and the plate-shaped portion 70e, that is, the relative positional relationship between the frame 41 and the reflectors 71a and 71b can be changed.

Corner reflectors are used as the reflectors 71a, 71b, with respect to the corner reflectors, the incident light and the reflected light are in point-symmetrical positions with respect to the center of the corner reflectors. Therefore, in order to reflect the light from the illuminating parts 26a, 26b disposed on the front of the reflectors 71a, 71b toward the front by the reflectors 71a, 71b, it is necessary to accurately position the center of the reflectors 71a, 71b. In this embodiment, the reflectors 71a and 71b can be accurately positioned by changing the relative positional relationship between the plate-shaped portion 70d and the plate-shaped portion 70e.

The length of the rod-shaped member 70a is greater than the horizontal distance L1 (see FIG. 5 ) between the first mounting portion 70b and the irradiating portions 26a, 26b (see FIG. 3 ) when the frame 41 is located at the loading position (refer to the dotted line in FIG. 5 ). In addition, the thickness of the rod-shaped member 70a is equal to or greater than the thickness t1 of the frame 41 . By making the rod-shaped member 70a relatively thick to prevent bending of the rod-shaped member 70a. In this embodiment, the thickness (diameter) of the rod-shaped member 70a is approximately 40 mm to approximately 50 mm, and the length of the rod-shaped member 70 a is approximately 400 mm to approximately 500 mm.

The material of the rod-shaped member 70a will be described. Metal, inorganic materials (glass, ceramics, etc.), and resin materials can be used for the rod-shaped member 70a. Moreover, a composite material can be used for the rod-shaped member 70a. Examples of composite materials include fibers or paper impregnated with a resin, and fibers or fine particles dispersed in a resin. Furthermore, the rod-shaped member 70a can also use what bonded the parts which consist of a single material or a composite material.

Examples of metals include iron, aluminum, titanium, stainless steel alloys, indium steel (invariant steel), etc., and the most ideal is a high-performance metal material (super indium steel) with a very small coefficient of thermal expansion near room temperature. As a glass material, quartz glass, low expansion glass, etc. are mentioned. Examples of ceramic materials include alumina, zirconia, silicon carbide (SiC), aluminum nitride (AlN), and low thermal expansion ceramic materials. Examples of fibers include carbon fibers (including carbon nanotubes, etc.), glass fibers, alumina fibers, steel fibers, and the like. Examples of fine particles include carbon black fine particles, mica fine particles, and the like. Examples of resin materials include polyethylene (PE), polypropylene (PP), polystyrene (PS), epoxy resin, polycarbonate (PC), cellulose-based resin, polyetherimide (PEI), liquid crystal polymer (LCP), polyethylene terephthalate (PET), polyvinyl chloride (PVC), ethylene-vinyl acetate copolymer resin (EVA resin), polyimide, polymethyl methacrylate (PMMA), polyester, polyurethane, and phenol. As a bonding material, for example, one or both sides of a metal plate (thin plate) as a core material is bonded with rubber, resin, etc. (preferably one that attenuates vibrations highly).

Among these materials, it is preferable to form the rod-shaped member 70a using a lightweight and highly rigid composite material, especially fiber-reinforced plastic. Among them, it is preferable to use carbon fiber reinforced plastic (carbon FRP) with a low thermal expansion rate and good dimensional stability to form the rod-shaped member 70a. The resin impregnated into the fiber is preferably a thermosetting resin and highly rigid epoxy resin, acrylic resin, or polyimide.

Fig. 8 is a schematic diagram of forming the rod-shaped member 70a using carbon FRP. Furthermore, as shown in Figure 8 A portion of fibers included in the rod-shaped member 70a is schematically shown. The rod-shaped member 70a is formed, for example, by winding a resin-impregnated sheet formed by arranging carbon fibers multiple times around a round rod-shaped mold, and hardening (thermally polymerizing) at high temperature (approximately 200° C. or higher). Examples of the weaving method of fibers in sheet form include unidirectional (UD) material, plain weave, and twill weave.

In this embodiment, the direction of the fiber contained in the rod-shaped member 70a is characteristic. In this embodiment, the direction of carbon fiber is inclined with respect to the axis|shaft of the rod-shaped member 70a. There are two directions of the carbon fibers, and they are line-symmetrical with respect to the axis ax when viewed from a direction substantially perpendicular to the axis ax of the rod-shaped member 70a. The slope of the carbon fiber with respect to the axis ax of the rod-shaped member 70a may be any angle, for example, approximately 45 degrees. By inclining the direction of the fiber with respect to the axis ax of the rod-shaped member 70a in this manner, expansion and contraction of the rod-shaped member 70a due to temperature changes can be prevented, thereby preventing positional changes of the reflectors 71a, 71b.

The thickness t of the rod-shaped member 70a is approximately 1/100 to approximately 1/40 of the diameter d of the rod-shaped member 70a. Here, the diameter d of the rod-shaped member 70 a is approximately 40 mm to approximately 50 mm, and the thickness t of the rod-shaped member 70 a is approximately 0.5 mm to approximately 1 mm. Thereby, the strength of the rod-shaped member 70a can be maintained.

In addition, the direction of the fiber contained in the rod-shaped member 70a shown in FIG. 8 is an example. FIG. 9 is a schematic diagram of a rod-shaped member 70a' of a modification. Furthermore, FIG. 9 schematically shows a part of fibers included in the rod-shaped member 70a'. The direction of the carbon fiber is two kinds of a direction substantially parallel to the axis ax of the rod-shaped member 70a' and a direction substantially perpendicular to the axis ax of the rod-shaped member 70a'. However, since the direction of the carbon fibers is inclined relative to the axis ax of the rod-shaped member 70a as shown in FIG. 8, the rod-shaped member 70a is less likely to be compressed and deformed.

Moreover, the direction of the fiber contained in the rod-shaped member 70a may be two or more types. For example, one rod-shaped member may include fibers in a direction approximately parallel to the axis of the rod-shaped member 70a', fibers in a direction approximately perpendicular to the axis of the rod-shaped member 70a' (see FIG. 9 ), and fibers inclined to the axis of the rod-shaped member 70a' (refer to FIG. 8 ).

FIG. 10 is a block diagram showing the electrical configuration of the photomask inspection apparatus 1 . The photomask inspection apparatus 1 has a CPU (Central Processing Unit) 151, a RAM (Random Access Memory) 152, ROM (Read Only Memory) 153 , input/output interface 154 , communication interface 155 , and media interface 156 .

CPU151 operates according to the program stored in RAM152 and ROM153, and has the function of the control part 151a which controls each part of the photomask inspection apparatus 1. RAM152 is a volatile memory. ROM153 is a non-volatile memory for storing various control programs and the like. CPU151 operates according to the program stored in RAM152 and ROM153, and performs control of each part. RAM 152 stores programs executed by CPU 151 , data used by CPU 151 , and the like. The ROM 153 stores an activation program executed by the CPU 151 when the mask inspection apparatus 1 is activated, a program dependent on the hardware of the mask inspection apparatus 1 , and the like. The program is read from the storage medium 143 , installed in the mask inspection apparatus 1 via the RAM 152 , and executed by the CPU 151 , for example.

The CPU 151 controls the input/output device 141 such as a keyboard or a mouse through the input/output interface 154 . The communication interface 155 receives data from other machines via the network 142 and sends them to the CPU 151 , and at the same time sends the data generated by the CPU 151 to other machines via the network 142 . The media interface 156 reads the programs or data stored in the storage medium 143 and stores them in the RAM 152 . Furthermore, the storage medium 143 is, for example, an IC card, SD card, DVD, or the like.

In addition, the structure of the photomask inspection apparatus 1 shown in FIG. 10 has demonstrated the main structure when explaining the characteristic of this embodiment, and does not exclude the structure with which, for example, a general information processing apparatus has. The constituent elements of the photomask inspection apparatus 1 can be classified into more constituent elements according to the processing content, and one constituent element can execute the processing of a plurality of constituent elements.

Next, the operation of the photomask inspection apparatus 1 will be described using FIG. 1 . First, the control part 151a arrange|positions the frame 41 in the loading position (refer FIG. 5), and controls the nail|claw part 41a etc. to hold the photomask M by the frame 41. As shown in FIG. Moreover, the control part 151a adjusts the position of the height direction (y direction) of the lower side of the mask M by the adjustment mechanism 42.

Next, the control part 151a moves the moving part 30 to -x direction along groove 10f, and moves the photomask M from a loading position to an inspection position. The control unit 151a controls the light source 53 and the like to emit light from the irradiation unit 26a. again, The control unit 151a detects the position of the frame 41 in the x direction by comparing the light irradiated from the illuminating unit 26a by the reflector 71a to obtain information related to the time from the illuminating unit 26a until it is received by the illuminating unit 26a, and comparing it with position information (stored in the ROM 153). The control unit 151a moves the frame 41 to a predetermined specific position while detecting the position of the frame 41 as described above.

Moreover, the control part 151a controls the light source 53 etc., and emits light from the irradiation part 26b. And the position of the frame 41 in the x direction is detected in the same manner as the processing performed on the irradiation section 26a.

After the photomask M moves to the inspection position, the control unit 151a controls the imaging unit 20 to detect the pattern formed on the photomask M. Then, the control unit 151a acquires pattern information, and detects to what extent a pattern along the x direction (hereinafter referred to as pattern x) is inclined relative to the x direction among the patterns. After the control unit 151a detects the slope of the pattern x, according to the rotation information (stored in the ROM 153) and the detection result at the position detection unit 25, the rotation drive unit 431 is controlled to rotate the frame 41, so that the horizontal component in the pattern becomes substantially horizontal (correction slope).

After the control part 151a rotates the frame 41, it moves the frame 41 (reticle M) to an inspection position again. Then, the control part 151a performs the inspection of the mask M by the imaging part 20. In this embodiment, g-rays are irradiated from the transmission illumination source and e-rays are irradiated from the reflection illumination source simultaneously, and these are simultaneously received by the cameras 22a and 22b and imaged. Then, each of the image captured by the camera 22a and the image captured by the camera 22b is compared with the image generated from the pattern information (stored in the ROM 153 ), thereby finding defects in the pattern and the like. The inspection method of the photomask M can use known technology, so the detailed description is omitted.

Since the holding member 70 is lightweight, the holding member 70 does not resonate at frequencies below 400 Hz. Since various vibrations in the factory (vibration of the casing covering the photomask inspection device 1, vibration when the linear motor is driven, pressure vibration of the fan filter unit, etc.) are mostly at a frequency below 400 Hz, the holding member 70 will not resonate during inspection, and the reflectors 71a and 71b will not vibrate either. As a result, suspicious defects are less likely to occur during inspection.

After the inspection of the entire surface of the mask M is completed, the control unit 151a moves the frame 41 (mask M) to the loading position again. Then, replace the photomask M, and move to the inspection of the next photomask M.

According to this embodiment, since the holding member 70 is formed using the hollow rod-shaped member 70a, the holding member 70 can be made light and durable. Thereby, the resonance of the holding member 70 caused by various vibrations in the factory can be prevented, and the vibration of the reflectors 71a and 71b can be prevented from causing suspected defects during inspection.

For example, when using a conventionally used holding member, such as a heavy holding member made of a metal base material with metal as a base material and a reinforcing material such as ceramics added, or a holding member formed by arranging a plurality of metal rods, resonance occurs at a frequency below 400 Hz. 11 is an example of a relatively heavy holding member 710 made of a metal base material. FIG. 12 is a diagram showing the vibration of the holding member 710 at 24 Hz. (A) shows the vibration of the reflector mounting plate 710a in the holding member 710 disposed on the upper end side (higher position) of the frame 41, and (B) represents the vibration of the reflector mounting plate 710a in the holding member 710 disposed on the lower end side (lower position) of the frame 41. In FIG. 12 , the vertical axis represents amplitude (μm), and the horizontal axis represents time (msec). The reflector mounting plate 710 a of the holding member 710 provided on the upper end side of the frame 41 vibrates at a low frequency of 24 Hz with an amplitude of 40 to 50 nm. Since the low-frequency vibration of around 24Hz is especially common in the vibration in the workshop, the vibration of the reflector under low-frequency conditions will have a greater impact on the occurrence of suspected defects.

Also, Figure 13 arranges 3 rods formed by the diameter of about 10mm formed by ultra -steel and uses a plate -shaped component to reinforce the component 720. Figure 14 shows a diagram of maintaining the vibration of 180Hz of the component 720. ) Indicates the vibration of the reflex installation board 720A in the holding component 720 under the end side of the frame 41. In FIG. 14 , the vertical axis represents amplitude (μm), and the horizontal axis represents time (msec). The reflector mounting plate 720a of the holding member 720 provided on the upper end side of the frame 41 vibrates at 180 Hz with an amplitude greater than 30 nm. In the factory, although the vibration of 180Hz is less than the vibration of low frequency, it occurs regularly and becomes the cause of suspected defects.

On the other hand, FIG. 15 is a diagram showing the vibration of 12.5 Hz when the holding member 70 of the present embodiment is used, and (A) shows the vibration of the plate-like portion 70e of the holding member 70 provided on the upper end side of the frame 41. Motion, (B) represents the vibration of the plate-like portion 70e in the holding member 70 provided on the lower end side of the frame 41. In FIG. 15 , the vertical axis represents amplitude (μm), and the horizontal axis represents time (msec). This 12.5 Hz vibration is generated when the moving part 30 moves along the groove 10f, etc., and is not a vibration caused by resonance. In addition, the amplitude of the vibration of 12.5 Hz is also small, about 8 nm. That is, when the holding member 70 is used, the plate-like portion 70e does not vibrate largely at a frequency of 400 Hz or less. As described above, by using the light and durable holding member 70, the vibration of the reflectors 71a, 71b caused by the resonance of the holding member 70 can be prevented, thereby preventing the occurrence of suspected defects.

Furthermore, in this embodiment, the rod-shaped member 70a is a hollow round rod, but the shape of the end face (cross section) of the rod-shaped member 70a is not limited thereto. The rod-shaped member may be a rod-shaped member whose end surface (section) is substantially polygonal, or may be a rod-shaped member whose end surface is substantially elliptical. In addition, the rod-shaped member may be a rod-shaped member formed by combining a plurality of plate-shaped members so that the end surfaces thereof become substantially polygonal. However, from the standpoint of strength, it is preferable to use a hollow tubular member (such as a hollow round rod or a hollow square rod) as the rod-shaped member 70a without a joint line on the side. Also, from the viewpoint of reducing the directional dependence of resonance, it is preferable to provide one rod-shaped member 70a. Furthermore, in order to eliminate the directional dependence of the strength in the cross-sectional direction and make the rigidity uniform, it is preferable to make the rod-shaped member 70a a hollow round rod.

Moreover, in this embodiment, although the one rod-shaped member 70a which does not have a connection part is used, the form of the rod-shaped member 70a is not limited to this. For example, a hollow round rod can be produced by bending and joining plate-like materials. Moreover, it is also possible to make a rod-shaped member using a plurality of members with a hollow structure. In addition, a hollow rod may be provided with a reinforcing structure such as a rib structure on the outer peripheral surface or hollow portion thereof as a rod-shaped member. Furthermore, holes or the like may be provided on the side of the hollow rod.

Also, in this embodiment, the first mounting portion 70b and the second mounting portion 70c are provided at both ends of the rod member 70a, but the forms of the first mounting portion 70b and the second mounting portion 70c are not limited to those shown in the figure.

As mentioned above, the embodiment of the present invention has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like within the range not departing from the gist of the present invention are also included.

The present invention can also be applied to a device that holds and inspects the mask M in a substantially horizontal direction. However, the present invention is particularly effective when the substantially frame-shaped frame 41 holds the photomask to be inspected in a substantially vertical direction, and the holding member 70 is provided at a higher position on the frame 41 .

In addition, in the present invention, the so-called "approximately" includes not only the situation of strict agreement, but also the concept of error or deformation to the extent that the agreement is lost. For example, the so-called substantially cubic shape is not limited to a strictly cubic shape. For example, although the recessed part 10b etc. are formed in the platform 10, the platform 10 has a substantially cubic shape as a whole. Also, for example, when only expressing vertical, consistent, etc., not only strictly vertical, consistent, etc., but also approximately vertical, substantially consistent, etc.

In addition, the so-called "near" in the present invention means the vicinity of A when it is, for example, the vicinity of A, which means the concept that A may or may not be included.

41: frame

41c: hole

70: Keeping components

70a: Rod member

70b: The first installation part

70c: The second installation part

70d, 70e: plate-shaped part

701: Plane Department

702: screw hole

703: round hole

704: screw hole

705: long hole

706: hole

707: back

Claims (9)

A photomask inspection device, characterized in that it has platform; A generally frame-shaped frame that holds the reticle of the object to be inspected; a moving part that moves the frame horizontally along the upper surface of the platform; a holding member disposed on the side of the frame; a reflector disposed at the front end of the holding member; a column, which is placed on the above-mentioned platform; and a light irradiation unit provided on the column, arranged at substantially the same height as the reflector, and irradiates light in a substantially horizontal direction toward the reflector; The above-mentioned holding member has: a hollow rod-shaped member extending along the horizontal direction; a first installation part provided at a first end of the above-mentioned rod-shaped member for mounting the above-mentioned rod-shaped member on the above-mentioned frame; and a second installation part provided at a second end of the end of the above-mentioned rod-shaped member opposite to the first end; The reflector is provided on the second mounting portion. Such as the photomask inspection device of claim item 1, wherein, The thickness of the above-mentioned rod-shaped member is equal to or greater than the thickness of the above-mentioned frame. Such as the photomask inspection device of claim item 1, wherein, The above-mentioned rod-shaped member is a hollow round rod, The wall thickness of the rod-shaped member is approximately 1/40 to approximately 1/50 of the diameter of the rod-shaped member. Such as the photomask inspection device of claim 2, wherein, The above-mentioned rod-shaped member is a hollow round rod, The wall thickness of the rod-shaped member is approximately 1/40 to approximately 1/50 of the diameter of the rod-shaped member. The photomask inspection device according to any one of claims 1 to 4, wherein, The rod-shaped member is formed of fiber-reinforced plastic. Such as the photomask inspection device of claim item 5, wherein, The direction of the fibers contained in the rod-shaped member is inclined with respect to the axis of the rod-shaped member. The photomask inspection device according to any one of claims 1 to 4, wherein, The moving unit horizontally moves the moving unit between a loading position for loading the photomask on the frame and an inspection position for inspecting the photomask, The length of the rod-shaped member is greater than or equal to the distance in the horizontal direction between the first mounting portion and the light irradiation portion when the frame is located at the loading position. Such as the photomask inspection device of claim item 5, wherein, The moving unit horizontally moves the moving unit between a loading position for loading the photomask on the frame and an inspection position for inspecting the photomask, The length of the rod-shaped member is greater than or equal to the distance in the horizontal direction between the first mounting portion and the light irradiation portion when the frame is located at the loading position. Such as the photomask inspection device of claim item 6, wherein, The moving unit horizontally moves the moving unit between a loading position for loading the photomask on the frame and an inspection position for inspecting the photomask, The length of the rod-shaped member is greater than or equal to the distance in the horizontal direction between the first mounting portion and the light irradiation portion when the frame is located at the loading position.

Images