JP7748845B2 - Halftone mask defect repair equipment - Google Patents

Description

The present invention relates to a half-tone mask defect repair device that repairs defects that occur in the semi-transparent portion of a half-tone mask.

Halftone masks are known as a photolithography technique. Halftone masks have semi-transparent sections with a transmittance between that of the transparent and light-shielding sections, allowing for multiple tones (three or more)—two tones of white in the transparent sections and black in the light-shielding sections—and intermediate tones (gray tones) between white and black in the semi-transparent sections. Therefore, they are also called multi-tone photomasks. Using a halftone mask makes it possible to form patterns in the photoresist with different exposure amounts in a single exposure. This reduces the number of photomasks used, reduces the number of manufacturing processes, and ultimately reduces manufacturing costs.

In half-tone masks, two main types of defects can occur due to issues in the manufacturing process. One is a defect in which there is a defect in part of the semi-transparent area (the presence of a defect increases transmittance, so this is called a "white defect"). The other is a defect in which there is excess or foreign matter in part of the semi-transparent area (the presence of foreign matter decreases transmittance, so this is called a "black defect").

When such defects occur, they must be repaired. In the case of white defects, they are repaired by forming a repair film over the defective area. In the case of black defects, they are repaired by removing the foreign matter or the part of the semi-transparent area where the foreign matter is present, and then forming a new repair film as necessary.

A known defect repair device is the one described in Patent Document 1. This device deposits a repair film using the laser CVD (Chemical Vapor Deposition) method. Specifically, this device deposits a CVD repair film by passing a laser beam emitted from a laser oscillator through an aperture, focusing it with an objective lens, and irradiating it onto the surface of a photomask to be repaired, which is placed in a reactive gas atmosphere.

JP 2017-173670 A

The defect repair device described in Patent Document 1 forms a repair film large enough to fill the defect repair area by forming multiple unit repair films in a two-dimensional array at a pitch where adjacent films overlap. However, due to the intensity distribution (Gaussian distribution) of the laser beam, the unit repair film has a convex shape with a thin film thickness at the periphery and a thick film thickness in the center. This makes it easy for the film thickness of the repair film to become uneven beyond the allowable range, which in turn makes it easy for the transmittance of the repair film to become uneven.

The present invention was developed in light of these circumstances, and aims to provide a defect repair device for half-tone masks that can improve the uniformity of the repair film's thickness, thereby producing a high-quality repair film with no uneven transmittance.

The apparatus for repairing a defect in a half-tone mask according to the present invention comprises:
a stage on which a half-tone mask is placed;
a laser beam emitting device;
an optical member having an optical action portion having a shape larger than the beam diameter of the laser beam, the optical action portion reducing the peak intensity at the central axis of the laser beam passing through the optical action portion;
a beam expander that expands the beam diameter of the laser beam;
a beam scanning unit that uses a spatial light modulation element to scan the laser beam that has passed through the beam expander and the optical member, thereby irradiating the laser beam onto a defect correction target area of the halftone mask in a planar manner;
The defect repair device for a half-tone mask is provided with a gas supply system that supplies a region to be repaired with a source gas atmosphere that is a raw material for the repair film.

Here, as one aspect of the half-tone mask defect repair device according to the present invention,
The optical action portion may have at least one of a filtering effect that makes the rate of decrease in intensity of the portion of the laser beam that passes through the center of the optical action portion higher than the rate of decrease in intensity of the portion of the laser beam that passes through the periphery of the optical action portion, or a diffusing effect that diffuses the laser beam.
In another aspect of the half-tone mask defect repair device according to the present invention,
The optical action portion is a cloudy portion formed by clouding part of the surface of the transparent member.
The above configuration can be adopted.

In addition, as another aspect of the halftone mask defect repair device according to the present invention,
The defect correction target area of the halftone mask is set for defects of 20 μm or less in size.
The above configuration can be adopted.
In still another aspect of the halftone mask defect repair device according to the present invention,
a glass plate covering an outlet opening of a housing of the laser beam emitting device;
The optical member is a glass plate provided separately from this glass plate.
The above configuration can be adopted.

In addition, as another aspect of the halftone mask defect repair device according to the present invention,
The optical element may further include an optical element support device that supports the optical element so that its position can be adjusted relative to the center of the optical path in a plane perpendicular to the optical path of the laser beam.

According to the present invention, the laser beam emitted from the laser beam emitter has its beam diameter expanded by the beam expander, and the peak intensity at the central axis is reduced by the optical action portion of the optical element, resulting in an overall smoothed beam that is irradiated in a planar manner onto the defect repair target area of the halftone mask. Therefore, according to the present invention, the uniformity of the repair film's film thickness can be improved, thereby obtaining a high-quality repair film with consistent transmittance.

1A is a schematic diagram of a defect correction device for a half-tone mask according to an embodiment, and FIGS. 1B and 1C are schematic diagrams of slits in the defect correction device. Fig. 2(a) is a schematic diagram of a laser optical system of a defect repair device. Fig. 2(b) is a plan view of an optical element used in the laser optical system. Fig. 2(c) is an explanatory diagram of one example of the optical characteristics of the optical element. Fig. 2(d) is an explanatory diagram of another example of the optical characteristics of the optical element. 3A and 3B are a plan view and a side view of the optical element support device, respectively. 4A and 4B are front views of the optical element support device with the support base for the optical element removed. 5A to 5D are explanatory diagrams of a method for repairing a defect in a halftone mask. Fig. 6(a) is an explanatory diagram of a film formation image when no optical member is used, and Fig. 6(b) is an explanatory diagram of a film formation image when an optical member is used.

Below, a half-tone mask defect repair device and a half-tone mask defect repair method using the same according to one embodiment will be described with reference to Figures 1 to 6.

<Defect repair device>
First, the defect repair device will be described. As shown in Fig. 1(a), the defect repair device 10 is a device that forms a repair film (CVD film) using a laser CVD method. The defect repair device 10 mainly includes a laser optical system 20, a laser optical system 30, an optical system 40, a gas supply system 50, and a position control system 60.

The laser optical system 20 is a laser optical system for forming a repair film. It comprises a laser oscillator (CVD laser) 21, a shutter 22, a beam expander 23, an attenuator 24, and a beam scanning unit 25. The laser beam (laser light) emitted from the laser oscillator 21, which serves as a laser beam emitting device, has its beam diameter expanded by the beam expander 23, and is adjusted to an appropriate output by the attenuator 24 before being scanned by the beam scanning unit 25. The beam scanning unit 25 performs main scanning and sub-scanning using a reflective or transmissive spatial light modulation element such as a galvanometer mirror, a digital micromirror device (DMD), or a PLZT element.

The laser optical system 20 is shown in more detail in FIG. 2(a). The laser optical system 20 further includes a glass plate 26, a mirror 27, and an optical element 28. The glass plate 26 covers the open exit of the housing of the laser oscillator 21 to prevent dust and other particles from entering the housing. Changes in the temperature inside the housing of the laser oscillator 21 can alter the optical axis, affecting the wavelength conversion of the laser beam. The glass plate 26 also serves to maintain a constant temperature inside the housing of the laser oscillator 21. A pair of mirrors 27 is provided between the shutter 22 and the beam expander 23. The pair of mirrors 27 bends the optical path at right angles at two locations, ensuring that the central axis of the laser beam emitted from the laser oscillator 21 and the central axis of the scanning light emitted from the beam scanning unit 25 are parallel and opposite to each other. The mirror 27 is provided based on the layout of the laser optical system 20 and may not be necessary depending on the layout of the laser optical system 20.

The optical element 28 has an optical action portion that reduces the peak intensity at the central axis of the laser beam, and is positioned on the optical path between the pair of mirrors 27, 27. More specifically, the optical element 28 is positioned between the pair of mirrors 27, 27 so that the center of the optical action portion coincides with the center of the optical path.

As shown in Figure 2(b), the optical action portion is a cloudy portion 28b formed on the surface of glass plate 28a. Glass plate 28a is circular. Cloudy portion 28b is also circular. Cloudy portion 28b is larger than or the same size as the beam diameter of the laser beam. For example, while the beam diameter (diameter) of the laser beam is 1 mm to 2 mm, cloudy portion 28b is 1.5 mm to 2 mm, and has a size that is 70% to 100% of the beam diameter of the laser beam. This allows the laser beam to pass through cloudy portion 28b. Note that the size of cloudy portion 28b refers to the average width of cloudy portion 28b.

The opaque portion 28b can be configured in various forms. As one example, as shown in FIG. 2(c), the opaque portion 28b is formed by surface-processing a portion of the surface of the glass plate 28a to have a transmittance gradient in which the transmittance is lower in the center than in the periphery and higher in the periphery than in the center. As a result, the opaque portion 28b has a filtering effect that increases the intensity reduction rate of the portion of the laser beam that passes through the center of the opaque portion 28b compared to the intensity reduction rate of the portion of the laser beam that passes through the periphery of the opaque portion 28b. Alternatively, as another example, as shown in FIG. 2(d), the opaque portion 28b is formed by surface-processing a portion of the surface of the glass plate 28a to create a rough surface, such as an uneven or jagged surface. As a result, the opaque portion 28b has a diffusing effect that diffuses the laser beam.

The optical element 28 is supported by the optical element support device 7 shown in Figures 3 and 4. The optical element support device 7 is disposed between a pair of mirrors 27, 27, and is attached to a mounting base 11 that directly or indirectly mounts components of the laser optical system 20, such as the pair of mirrors 27, 27 and the laser oscillator 21.

The optical element support device 7 comprises a fixed base 70, a first linear guide 71, a first slide base 72, a second linear guide 73, a second slide base 74, and a support base 75.

The fixed base 70 is in the shape of a vertical plate and is attached (at its lower part) to the mounting base 11. The fixed base 70 has an opening 70a (in its lower half) that penetrates from front to back and is centered on the center C of the optical path. The first linear guide 71 is attached (to the upper half of the fixed base 70) so that the longitudinal direction of the first linear guide 71 is aligned along one axial direction (e.g., the horizontal direction) of two orthogonal axes in a plane perpendicular to the optical path. The first slide base 72 is attached to the first linear guide 71 and is slidable in one axial direction (e.g., the horizontal direction). The second linear guide 73 is attached to the first slide base 72 so that the longitudinal direction of the second linear guide 73 is aligned along the other axial direction (e.g., the vertical direction). The second slide base 74 is attached to the second linear guide 73 and is slidable in the other axial direction (e.g., the vertical direction).

The support base 75 is in the form of a vertical plate and is attached to the second slide base 74 (at its upper half) so as to face the fixed base 70. The support base 75 has an opening 75a that penetrates from front to back and is coaxial with the opening 70a of the fixed base 70. The opening 75a is a circular hole the same size as the glass plate 28a of the optical element 28, and by fitting the optical element 28 into this opening, the support base 75 supports the optical element 28 (at its lower half). This configuration allows the optical element 28 to move in a plane perpendicular to the optical path.

The optical element support device 7 includes a first micrometer 76. The first micrometer 76 has a main body 76a attached to the fixed base 70 via a first mounting member 77, and is positioned along the sliding direction of the first slide base 72. The tip of the spindle 76b of the first micrometer 76 is rotatably engaged with an engagement portion 72a, which is part of the first slide base 72. With this configuration, by rotating the first micrometer 76, the position of the optical element 28 can be adjusted in one of two orthogonal axial directions (e.g., the horizontal direction) in a plane perpendicular to the optical path.

The optical element support device 7 is equipped with a second micrometer 78. The second micrometer 78 has a main body 78a attached to the first slide base 72 via a second mounting member 79, and is positioned along the sliding direction of the second slide base 74. The tip of the spindle 78b of the second micrometer 78 is rotatably engaged with an engaging portion 74a, which is part of the second slide base 74. With this configuration, by rotating the second micrometer 78, the position of the optical element 28 can be adjusted in the other axial direction (e.g., the vertical direction) of two orthogonal axes in a plane perpendicular to the optical path.

With the above configuration, the position of the optical element 28 can be adjusted relative to the center C of the optical path in a plane perpendicular to the optical path. This allows the opaque portion 28b of the optical element 28 to be positioned so that the center of the opaque portion 28b coincides with the center C of the optical path.

Returning to Figure 1(a), the laser optical system 30 is a laser optical system for partially removing the semi-transparent film that makes up the semi-transparent portion. The laser optical system 30 comprises a laser oscillator (Zap Laser) 31, a shutter 32, a beam expander 33, and an attenuator 34. The laser beam (laser light) emitted in pulses from the laser oscillator 31 has its beam diameter expanded by the beam expander 33, and is adjusted to an appropriate output by the attenuator 34.

The optical system 40 guides the laser beams emitted from the laser optical systems 20 and 30 onto the surface of the halftone mask 8. The optical system 40 includes a prism 41, a prism 42, a slit 43, a prism 44, a prism 45, and an objective lens 46. The prism 41 reflects the laser beam emitted from the laser optical system 20. The prism 42 transmits the laser beam reflected by the prism 41 and reflects the laser beam emitted from the laser optical system 30. The slit 43 narrows the beam diameter of the laser beam transmitted through and reflected by the prism 42 to a predetermined size. The laser beam passing through the slit 43 is reflected by the prisms 44 and 45, passes through the objective lens 46, and is irradiated onto the surface of the halftone mask 8 placed on the stage 61.

The slit 43 defines a laser beam irradiation area on the surface of the halftone mask 8. As shown in Figures 1(b) and (c), the slit 43 comprises a first pair of frames 430, 430 that are parallel and whose spacing is adjustable, and a second pair of frames 431, 431 that are also parallel and whose spacing is adjustable and that are perpendicular to the first pair of frames 430, 430. The rectangular opening 432 (hatched area in the figure) surrounded by the four mutually perpendicular frames 430, 430, 431, 431 forms the laser beam irradiation area. The opening 432 can also be made slit-shaped by narrowing the spacing between one pair of frames.

The gas supply system 50 supplies the raw material gas used to form the repair film. The gas supply system 50 includes a raw material gas supply pipe 51. The raw material gas is generated by mixing a carrier gas consisting of an inert gas with raw material gasified by heating. The raw material gas supplied from the raw material gas supply pipe 51 is ejected toward the surface of the half-tone mask 8, creating a raw material gas atmosphere in the defect repair target area on the surface of the half-tone mask 8. When a laser beam from the laser optical system 20 is irradiated onto the surface of the half-tone mask 8 in this raw material gas atmosphere, an irradiation spot is formed, and a repair film is deposited according to the size and shape of the irradiation spot. Examples of raw materials that can be used include metal carbonyls such as chromium carbonyl, molybdenum carbonyl, and tungsten carbonyl.

The position control system 60 is used to position the portion of the half-tone mask 8 to be irradiated with laser light at the laser irradiation position (on the central axis of the objective lens 46). The position control system 60 includes a stage 61 and a position control unit 62. The half-tone mask 8 is placed on the stage 61, which is movable in the X and Y directions, which are perpendicular to each other, on a horizontal plane. The position control unit 62 controls the movement and position of the stage 61.

Mechanisms for changing the relative position of the laser irradiation position and the halftone mask 8 include a mechanism in which the stage 61 moves in the X and Y directions, as well as (i) a mechanism in which the stage is fixed and a head unit equipped with a laser irradiation unit (objective lens) moves in the X and Y directions, or (ii) a mechanism in which one of the head unit or the stage moves in the X direction and the other moves in the Y direction.

<Defect repair method>
Next, a defect repair method will be described. The defect repair method is used when the size of the defect is 20 μm or less, that is, when the size of the defect is within a square of 20 μm × 20 μm or less, and generally includes, as shown in Fig. 5 , (i) a trimming step (first step) of setting a defect repair target area 4 that includes a defect 3 generated in a semi-transparent portion 2 of a half-tone mask 8 and removing an existing semi-transparent film 2 that exists within the defect repair target area 4, and (ii) a repair film deposition step of depositing a repair film 7 in the defect repair target area 4 so that the transmittance thereof is equal to that of the semi-transparent portion 2 and so that the repair film 7 has a shape that matches the defect repair target area 4. The correction film deposition process also includes (ii-i) a base layer deposition process (second process) for depositing a base layer 5 having a transmittance higher than that of the semi-transparent portion 2, and (ii-ii) a transmittance adjustment layer deposition process (third process) for depositing one or more transmittance adjustment layers 6 on the base layer 5 so that the transmittance is equal to that of the semi-transparent portion 2.

In the first step (trimming step), the opening shape of the slit 43 of the defect correction device 10 is aligned with the defect correction target area 4, and the laser optical system 30 is used to remove the existing semi-transparent film 2 that exists within the defect correction target area 4. This eliminates the defect 3 and forms a non-film-formed area with a rectangular outline, i.e., a transparent area where the transparent substrate 1 is exposed in a rectangular shape.

In the second process (base layer deposition process of the repair film deposition process), the opening shape of the slit 43 of the defect repair device 10 is aligned with the optical center of the beam scan unit 25 (the center of the galvanometer mirror in the case of a galvanometer mirror), and the opening shape of the slit 43 is aligned with the defect repair target area 4. Then, using the laser optical system 20, a base layer 5 is formed within the defect repair target area 4. The base layer 5 is deposited by continuously irradiating the laser beam while performing main and sub-scanning of the laser beam using the beam scan unit 25. The base layer 5 is formed in a rectangular shape corresponding to the opening shape of the slit 43 of the defect repair device 10.

As described above, the base layer 5 is a CVD film. The transmittance of the base layer 5 is higher than that of the semi-transparent portion 2. This is because the transmittance of the correction film 7 is adjusted by laminating a transmittance adjustment layer 6 to reduce the transmittance. The transmittance of the base layer 5 is preferably set to be greater than or equal to +10% and less than or equal to +20% of the transmittance of the semi-transparent portion 2. In this embodiment, the transmittance of the semi-transparent portion 2 is 30%, while the transmittance of the base layer 5 is 40%.

In the third process (transmittance adjustment layer deposition process of the repair film deposition process), the opening shape of the slit 43 of the defect repair device 10 is aligned with the optical center of the beam scan unit 25 (the center of the galvanometer mirror in the case of a galvanometer mirror), and the opening shape of the slit 43 is aligned with the defect repair target area 4. Then, using the laser optical system 20, the transmittance adjustment layer 6 is formed within the defect repair target area 4. As with the base layer 5, the transmittance adjustment layer 6 is deposited by continuously irradiating the laser beam while main-scanning and sub-scanning the laser beam using the beam scan unit 25. The transmittance adjustment layer 6 is formed in a rectangular shape corresponding to the opening shape of the slit 43 of the defect repair device 10.

During the transmittance adjustment layer deposition process, the transmittance of the correction film 7 is measured each time the transmittance adjustment layer 6 is deposited. Various known transmittance measurement methods can be used, including a direct method of measuring transmittance by irradiating light (for example, at one point in the center of the correction film 7) and measuring the amount of transmitted light, as well as an indirect method of measuring transmittance by capturing an image of the correction film 7 (for example, its pixel values) and comparing it with an image of the semi-transparent portion 2 (for example, its pixel values).

When the measurement results show that the transmittance of the correction film 7 is the same as that of the semi-transparent section 2, or that the difference between the transmittance of the correction film 7 and that of the semi-transparent section 2 is negligible, the transmittance adjustment layer deposition process, and ultimately the correction film deposition process, is complete.

Through the above steps, a repair film 7 is obtained that has a uniform transmittance across the entire surface of the defect repair target area 4 and that is equal to the transmittance of the semi-transparent portion 2, which is made up of normal semi-transparent film around the defect repair target area 4. Furthermore, to obtain a repair film 7 of higher quality, if necessary, a compensation film deposition process may be carried out, as described in Japanese Patent No. 6741893, in which a compensation film is deposited on the high-transmittance portion that remains in the defect repair target area 4 even after the repair film 7 is deposited, so that the transmittance is equal to that of the semi-transparent portion 2.

If the defect occurs in the semi-transparent portion near the boundary between the semi-transparent and transparent portions, trimming may be performed by aligning the slit 43 so that it forms a U-shape connected to the transparent portion, or by rotating the slit 43 by a predetermined angle so that it forms a roughly triangular shape. In the latter case, trimming may be performed by depositing the repair film 7 with the rotation angle of the slit 43 adjusted, and then removing any repair film 7 that extends beyond the edge line of the semi-transparent portion using the laser optical system 30.

<Effects of this embodiment>
As described above, the opaque portion 28b of the optical member 28 has a filtering effect, which makes the intensity reduction rate of the laser beam passing through the center of the opaque portion 28b higher than the intensity reduction rate of the laser beam passing through the peripheral portion of the opaque portion 28b, or a diffusing effect, which diffuses the laser beam. As a result, as shown in Figure 6(b), the laser beam irradiated on a surface by the main scanning and sub-scanning of the beam scanning unit 25 is smoothed overall. This improves the uniformity of the film thickness of the correction film 7, thereby enabling the production of a high-quality correction film 7 with uniform transmittance.

The optical element 28 is supported by the support base 75 of the optical element support device 7, which is movable on two orthogonal axes in a plane perpendicular to the optical path, and is movable in the plane perpendicular to the optical path. This allows the position of the optical element 28 to be adjusted relative to the center C of the optical path in the plane perpendicular to the optical path.

The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

In the above embodiment, the optical element 28 is disposed between the pair of mirrors 27, 27 in the laser optical system 20. However, the present invention is not limited to this. The optical element can be disposed anywhere on the optical path from the laser oscillator (or shutter) to the beam expander. Alternatively, the optical element may also serve as a glass plate covering the outlet opening of the laser oscillator housing.

Furthermore, in the above embodiment, the optical action portion (opaque portion 28b) is provided on a portion of the surface of the glass plate 28a of the optical member 28. However, the present invention is not limited to this. The optical action portion (opaque portion) may be provided on the entire surface of the glass plate. Further, in the above embodiment, the optical member is constructed using a glass plate. However, the present invention is not limited to this. The optical member may be another form of transparent member, such as a transparent resin plate.

Furthermore, the above embodiment describes the defect repair of a white defect. However, the defect to be repaired may also be a black defect.

In addition, in the above embodiment, the defect repair target area 4 and the trimming area are rectangular due to the structure of the slit 43 of the defect repair device 10. However, by using an appropriate mask shape, the defect repair target area and the trimming area can be set to any appropriate shape. Alternatively, by appropriately controlling the laser beam, it is possible to form a repair film without using a slit.

In addition, in the above embodiment, a trimming process is performed. However, depending on the shape of the defect, it may be possible to set the defect itself as the defect correction target area. In this case, the trimming process is not necessary.

In addition, in the above embodiment, the repair film deposition process includes a base layer deposition process and a transmittance adjustment layer deposition process. However, if the desired repair film can be obtained using only the base layer, the transmittance adjustment layer deposition process is not necessary.

1...Transparent substrate (glass substrate), 2...Semi-transparent film (semi-transparent portion), 3...Defect (white defect), 4...Trimming area (area to be repaired defect), 5...Base layer, 6...Transmittance adjustment layer, 7...Repair film, 8...Half-tone mask, 10...Defect repair device, 11...Mounting base, 20...Laser optical system, 21...Laser oscillator, 22...Shutter, 23...Beam expander, 24...Attenuator, 25...Beam scan unit, 26...Glass plate, 27...Mirror, 28...Optical member, 28a...Glass plate, 28b...Optical portion, 30...Laser optical system, 31...Laser oscillator, 32...Shutter, 33...Beam expander, 34...Attenuator, 40...Optical system, 41...Prism, 42...Prism, 43...Slit, 430 ...frame, 431...frame, 432...aperture, 44...prism, 45...prism, 46...objective lens, 50...gas supply system, 51...source gas supply pipe, 60...position control system, 61...stage, 62...position control unit, 7...optical element support device, 70...fixed base, 70a...aperture, 71...first linear guide, 72...first slide base, 72a...engagement portion, 73...second linear guide, 74...second slide base, 74a...engagement portion, 75...support base, 75a...aperture, 76...first micrometer, 76a...main body, 76b...spindle, 77...first mounting member, 78...second micrometer, 78a...main body, 78b...spindle, 79...second mounting member, S...defect size, C...center of optical path

Claims (6)

a stage on which a half-tone mask is placed;
a laser beam emitting device;
an optical member having an optical action portion having a shape larger than the beam diameter of the laser beam, the optical action portion reducing the peak intensity at the central axis of the laser beam passing through the optical action portion;
a beam expander that expands the beam diameter of the laser beam;
a beam scanning unit that uses a spatial light modulation element to scan the laser beam that has passed through the beam expander and the optical member, thereby irradiating the laser beam onto a defect correction target area of the halftone mask in a planar manner;
A half-tone mask defect repair device comprising: a gas supply system for supplying a region to be repaired with a source gas atmosphere that is a raw material for a repair film. 2. The halftone mask defect repair device according to claim 1, wherein the optical action portion has at least one of a filtering effect that makes the rate of decrease in intensity of the portion of the laser beam that passes through the center of the optical action portion higher than the rate of decrease in intensity of the portion of the laser beam that passes through the periphery of the optical action portion, or a diffusing effect that diffuses the laser beam. 3. The half-tone mask defect repair device according to claim 1, wherein the optical action portion is a cloudy portion obtained by clouding a part of the surface of a transparent member. The defect correction target area of the halftone mask is set for defects of 20 μm or less in size.
4. The apparatus for repairing a defect in a half-tone mask according to claim 1. a glass plate covering an outlet opening of a housing of the laser beam emitting device;
The optical member is a glass plate provided separately from this glass plate.
5. The apparatus for repairing a defect in a half-tone mask according to claim 1. 6. The half-tone mask defect repair device according to claim 1 , further comprising an optical member supporting device that supports the optical member so that its position can be adjusted relative to the center of the optical path in a plane perpendicular to the optical path of the laser beam.