JP2009121941A - Substrate inspection apparatus and manufacturing method of substrate for mask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate inspection apparatus capable of reliably detecting minute linear flaws extended along all directions. <P>SOLUTION: The substrate inspection apparatus for inspecting foreign matters in a substrate 30 comprises an illumination system 1 for illuminating the substrate with light, and a plurality of imaging systems 2:2a-2g for performing the dark field observation of a region on the substrate illuminated by the illumination system. The plurality of imaging systems are arranged so that the range of scattered light from the foreign matters illuminated by the illumination system at least partially overlaps with that of imaging luminous flux in the pupil surface of one of the imaging systems. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a substrate inspection apparatus and a method for manufacturing a mask substrate. More specifically, the present invention relates to detection of a scratch on a mask substrate used in a liquid crystal exposure apparatus for manufacturing a device such as a liquid crystal display element in a lithography process.

  There is a demand that a mask substrate (transparent glass substrate on which a transfer pattern is not formed) used in a liquid crystal exposure apparatus should not have any scratches (defects) having a length of about 2 μm, for example. However, it is very difficult to detect a linear (or slit-shaped) scratch formed on the surface of the substrate. This is because not only the contrast of the image formed by the scattered light from the minute linear scratches is low, but also the contrast changes remarkably depending on the illumination direction and the observation direction with respect to the scratches.

  For this reason, visual inspection using a high-illuminance illumination device is the mainstream, and the current situation is that visual inspection is performed while manually changing the illumination direction and the observation direction with respect to the inspection area of the substrate. Manual visual inspection methods are undesirable from the standpoint of reproducibility and cost. In view of this, a substrate inspection apparatus that irradiates inspection light onto a substrate inspection region from a plurality of directions and observes the forward scattered light from scratches in a dark field has been proposed (see Patent Document 1).

JP-A-4-344447

  In the substrate inspection apparatus disclosed in Patent Document 1, the angles of a plurality of inspection lights with respect to the normal line of the substrate are defined. However, this board inspection apparatus cannot reliably detect minute linear scratches extending in all directions, as will be described later in connection with the operation of the present invention.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a substrate inspection apparatus capable of reliably detecting minute linear scratches extending in all directions.

In order to solve the above problems, in the first embodiment of the present invention, in the substrate inspection apparatus for inspecting the foreign matter on the substrate,
An illumination system for illuminating the substrate;
A plurality of imaging systems for dark field observation of the area on the substrate illuminated by the illumination system;
The plurality of imaging systems are arranged such that the range of scattered light from the foreign object illuminated by the illumination system and the range of the imaging light beam overlap at least partially on the pupil plane of any one imaging system. A substrate inspection apparatus is provided.

In the second embodiment of the present invention, in the substrate inspection apparatus for inspecting the foreign matter on the substrate,
A plurality of illumination systems for illuminating the substrate;
An imaging system for dark field observation of the area on the substrate illuminated by the plurality of illumination systems;
The plurality of illumination systems are arranged on the pupil plane of the imaging system so that a range of scattered light from a foreign object illuminated by any one illumination system and a range of imaging light beams at least partially overlap each other. A substrate inspection apparatus is provided.

In the third embodiment of the present invention, in the method for manufacturing a mask substrate,
There is provided a manufacturing method including an inspection step of inspecting a foreign substance on the mask substrate using the substrate inspection apparatus according to the first aspect or the second aspect.

  In the substrate inspection apparatus of the present invention, at least on the pupil plane of any one imaging system, the range of scattered light from the foreign matter (such as a minute linear scratch) illuminated by the illumination system and the range of the imaging light flux are at least A plurality of imaging systems are arranged so as to partially overlap. Alternatively, on the pupil plane of the imaging system, a plurality of illumination systems are arranged so that the range of scattered light from the foreign object illuminated by any one illumination system and the range of the imaging light beam at least partially overlap each other. Yes. As a result, the substrate inspection apparatus of the present invention can reliably detect minute linear scratches extending along all directions.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of a substrate inspection apparatus according to an embodiment of the present invention. In the present embodiment, the present invention is applied to a substrate inspection apparatus that inspects a scratch on a mask substrate (hereinafter simply referred to as “substrate”) used in a liquid crystal exposure apparatus. Referring to FIG. 1, a substrate inspection apparatus according to the present embodiment includes an illumination system 1 that illuminates a substrate 30 to be inspected, and a plurality of imaging systems that perform dark field observation on a region on the substrate 30 illuminated by the illumination system 1. 2 are provided.

  The illumination system 1 includes, for example, a halogen lamp 11 as a light source that supplies illumination light (inspection light). The halogen lamp 11 is disposed at the first focal position of the elliptical mirror 12. The light from the halogen lamp 11 is reflected by the elliptical mirror 12 and then forms a light source image at the second focal position of the elliptical mirror 12. The light from the light source image is condensed by a condensing optical system 13 such as a collimator lens to form an illumination area on the substrate 30.

  The plurality of imaging systems 2 are arranged at the vertex positions of a polygon centering on the optical axis AX1 on an orthogonal plane orthogonal to the optical axis AX1 of the illumination system 1, for example. Hereinafter, in order to facilitate understanding of the description, the plurality of imaging systems 2 include seven imaging systems 2a to 2g arranged at the apexes of a regular heptagon with the optical axis AX1 as the center, and the imaging systems 2a to 2g. It is assumed that the angle formed by the optical axis AX2 of 2g and the optical axis AX1 is α.

  As each imaging system 2a-2g, a CCD camera can be used, for example. In FIG. 1, for the sake of clarity, the imaging system 2a disposed within the paper surface of FIG. 1 and the imaging system 2d disposed outside the paper surface of FIG. 1 are illustrated, and the other imaging systems 2b, 2c, Illustration of 2e, 2f, 2g is omitted. In general, detection of linear flaws formed on the surface of the substrate 30, particularly detection of linear flaws having a relatively smooth flaw mouth and isolated, is the most difficult in principle.

  FIG. 2 is a diagram schematically illustrating a state in which scattered light (diffracted light) is generated from linear flaws when irradiated with illumination light. As shown in FIG. 2, when the illumination light 32 is irradiated onto the linear scratch 31 formed on the surface of the substrate 30, the illumination light 32 is elongated in the short direction of the linear scratch 31 (the scratch 31 extends on the surface of the substrate 30. Diffracted in a direction perpendicular to the longitudinal direction. That is, scattered light (diffracted light) from the linear scratch 31 irradiated with the illumination light 32 spreads one-dimensionally along the short direction of the linear scratch 31.

  FIG. 3 is a diagram for explaining conditions necessary for detecting a linear flaw in the substrate inspection apparatus of the present invention. As shown in FIG. 3, when illumination light vertically enters a linear scratch 31 that extends along the vertical direction in the drawing on the surface of the substrate 30, the scattered light from the linear scratch 31 on the pupil plane of the imaging system 2. The range 34 is a straight line extending in the horizontal direction in the drawing. Actually, since the illumination light beam applied to the linear scratch 31 has a predetermined numerical aperture, the range 35 of the scattered light on the pupil plane of the imaging system 2 is the intensity distribution of the scattered light and the illumination with respect to the vertically incident illumination light. It is determined by convolution (convolution) with the intensity distribution of the luminous flux.

  In FIG. 3, a circle indicated by reference numeral 36 is a range of illumination light flux on the pupil plane (illumination pupil) of the illumination system 1. A circle indicated by reference numeral 37 is an illumination area (or an imaging field on the surface of the substrate 30) formed on the surface of the substrate 30. A circle indicated by reference numeral 38 is a range of the imaged light flux on the pupil plane of the imaging system 2. In order to reliably detect minute linear scratches 31 in all directions, the pupil plane of any one imaging system 2 is connected to the range 35 of scattered light from the linear scratches 31 illuminated by the illumination system 1. It is necessary that the image light flux range 38 at least partially overlap.

  FIG. 4 is a diagram for explaining conditions necessary for detecting a linear flaw in the substrate inspection apparatus according to the present embodiment. In FIG. 4, reference numeral 38a is a range of the imaged light flux on the pupil plane of the imaging system 2a. Similarly, reference numerals 38b to 38g are ranges of imaged light fluxes on the pupil planes of the imaging systems 2b to 2g, respectively. In this case, on the orthogonal plane orthogonal to the optical axis AX1 of the illumination system 1, the center position of the two adjacent imaging light beam ranges 38 (and thus the position of the two adjacent imaging systems) is centered on the optical axis AX1 of the illumination system 1. Is θoc (specifically, θoc = 360 / 7≈51.4 degrees).

Therefore, in order to reliably detect minute linear scratches 31 in all directions, the range 35 of scattered light from the linear scratches 31 illuminated by the illumination system 1 on the pupil plane of any one imaging system 2. In order for the imaging light beam range 38 to at least partially overlap, the following conditional expression (1) must be satisfied. In conditional expression (1), Da is the diameter of the illumination light beam range 36 on the pupil plane of the illumination system 1, and Db is the diameter of the imaging light beam range 38 on the pupil plane of the imaging system 2.
Da + Db> θoc · sin α / 2 (1)

  The sin α on the right side of the conditional expression (1) corresponds to the length of the line segment connecting the center of the illumination light beam range 36 and the center of each imaging light beam range 38 in FIG. 4, and θoc · sin α is the two adjacent image formations. This corresponds to the length of an arc connecting the centers of the light flux range 38. Therefore, the conditional expression (1) substantially corresponds to a condition in which the circle 36 indicating the illumination light beam range cannot pass between the center of the arc and each imaging light beam range 38.

  In the substrate inspection apparatus of this embodiment, 7 is arranged so as to satisfy the conditional expression (1) at the apex position of a regular heptagon centered on the optical axis AX1 on the orthogonal plane orthogonal to the optical axis AX1 of the illumination system 1. Two imaging systems 2a to 2g are provided. As a result, on the pupil plane of any one imaging system 2, the range 35 of scattered light from the minute linear scratch 31 illuminated by the illumination system 1 and the range 38 of the imaging light beam overlap at least partially. Thus, the minute linear scratch 31 extending along all directions can be reliably detected. In other words, the conventional substrate inspection apparatus disclosed in Patent Document 1 defines the angles of a plurality of inspection lights with respect to the normal line of the substrate. However, as long as the required conditions as described above are not satisfied, any direction is possible. It is impossible to reliably detect minute line-shaped scratches extending along the line.

  In the above description, the seven imaging systems 2a to 2g are arranged at the apex position of the regular heptagon with the optical axis AX1 of the illumination system 1 as the center. However, the present invention is not limited to this, and there are a plurality of odd-numbered regular polygons (regular pentagons, regular pentagons, etc.) at vertex positions on the orthogonal plane perpendicular to the optical axis AX1 of the illumination system 1. Even when the imaging system 2 is arranged, by satisfying the conditional expression (1), it is possible to reliably detect minute linear scratches extending along all directions. In the configuration in which a plurality of imaging systems are arranged at the vertex positions of an odd-numbered regular polygon, there is an advantage that a reflected image of another imaging system by the substrate is difficult to enter the field of view background.

On the other hand, when a plurality of imaging systems 2 are arranged at the vertex positions of an even-numbered regular polygon (regular hexagon, regular octagon, etc.) with the optical axis AX1 as the center in an orthogonal plane orthogonal to the optical axis AX1 of the illumination system 1 In order for the range 35 of the scattered light from the linear flaw 31 and the range 38 of the imaging light beam to overlap at least partially on the pupil plane of one imaging system 2, it is necessary to satisfy the following conditional expression (2): .
Da + Db> θec · sinα (2)

  In the conditional expression (2), θec is an angle formed by the center position of the two adjacent imaging light beam ranges 38 (and consequently the positions of the two adjacent imaging systems) about the optical axis AX1 of the illumination system 1. That is, for example, when eight image pickup systems 2 are arranged at the apex position of a regular octagon, θec = 360/8 = 45 degrees. Conditional expression (2) substantially corresponds to a condition in which the circle 36 indicating the illumination light beam range cannot pass between two adjacent imaging light beam ranges 38.

More generally, when a plurality of imaging systems 2 are arranged at the vertex positions of a polygon (not a regular polygon) with the optical axis AX1 as the center in an orthogonal plane orthogonal to the optical axis AX1 of the illumination system 1, In order to at least partially overlap the range 35 of scattered light from the linear scratch 31 and the range 38 of the imaging light beam on the pupil planes of the two imaging systems 2, the following conditional expression (3) similar to the conditional expression (2) ) Must be satisfied.
Da + Db> θmc · sinα (3)

  In conditional expression (3), θmc is the maximum value of the angle formed by the center position of the two adjacent imaging light beam ranges 38 (and thus the position of the two adjacent imaging systems 2) about the optical axis AX1 of the illumination system 1. It is. Conditional expression (3) substantially corresponds to a condition in which the circle 36 indicating the illumination light beam range cannot pass between the two imaging light beam ranges 38 adjacent to each other with the largest interval.

  In the above description, a plurality of imaging systems are arranged at the vertex positions of a polygon centered on the optical axis of one illumination system. However, the present invention is not limited to this, and by arranging a plurality of illumination systems at the vertex positions of a polygon centered on the optical axis of one imaging system, minute linear scratches extending in all directions can be generated. It can also be detected reliably. FIG. 5 is a diagram schematically showing a configuration of a substrate inspection apparatus according to a modification example in which a plurality of illumination systems are arranged at polygonal vertex positions around the optical axis of one imaging system.

  The substrate inspection apparatus according to the modification of FIG. 5 includes a plurality of illumination systems 1 that illuminate the substrate 30 and an imaging system 2 that observes a dark field area on the substrate 30 illuminated by the plurality of illumination systems 1. Yes. The plurality of illumination systems 1 are arranged at the vertex positions of a polygon centering on the optical axis AX2 in an orthogonal plane orthogonal to the optical axis AX2 of the imaging system 2, for example. Hereinafter, in order to facilitate understanding of the description, the plurality of illumination systems 1 includes seven illumination systems 1a to 1g arranged at the apex positions of regular heptagons with the optical axis AX2 as the center, and each illumination system 1a to 1g. It is assumed that the angle formed by the 1 g optical axis AX1 and the optical axis AX2 is β.

  As the illumination systems 1a to 1g, for example, an illumination system having an internal configuration shown in FIG. 1 can be employed. 5, for the sake of clarity, the illumination system 1a arranged in the plane of FIG. 5 and the illumination system 1d arranged outside the plane of FIG. 5 are illustrated, and the other illumination systems 1b, 1c, Illustrations of 1e, 1f, and 1g are omitted. In this case, in order to reliably detect minute linear scratches 31 in all directions, the range of scattered light from the linear scratches 31 illuminated by any one illumination system 1 on the pupil plane of the imaging system 2 35 and the imaging light flux range 38 must at least partially overlap.

  FIG. 6 is a diagram for explaining conditions necessary for detecting a linear flaw in the substrate inspection apparatus according to the modification of FIG. In FIG. 6, reference numeral 36a is a range of the illumination light beam on the pupil plane of the illumination system 1a. Similarly, reference numerals 36b to 36g are ranges of illumination light beams on the pupil planes of the illumination systems 1b to 1g, respectively. In this case, on the orthogonal plane orthogonal to the optical axis AX2 of the imaging system 2, the center position of the two adjacent illumination light beam ranges 36 (and thus the position of the two adjacent illumination systems) is centered on the optical axis AX2 of the imaging system 2. The angle formed is θoi (specifically, θoi = 360 / 7≈51.4 degrees).

Therefore, in order to reliably detect minute linear scratches 31 in all directions, the range 35 of scattered light from the linear scratches 31 illuminated by any one illumination system 1 on the pupil plane of the imaging system 2. In order for the imaging light beam range 38 to at least partially overlap, the following conditional expression (4) must be satisfied. In conditional expression (4), Da is the diameter of the illumination light beam range 36 on the pupil plane of the illumination system 1, and Db is the diameter of the imaging light beam range 38 on the pupil plane of the imaging system 2.
Da + Db> θoi · sinβ / 2 (4)

  The sin β on the right side of the conditional expression (4) corresponds to the length of the line segment connecting the center of each illumination light beam range 36 and the center of the imaging light beam range 38 in FIG. 6, and θoi · sin β is two adjacent illumination light beams. This corresponds to the length of the arc connecting the centers of the range 36. Therefore, the conditional expression (4) substantially corresponds to a condition in which the circle 38 indicating the imaging light beam range cannot pass between the center of the arc and each illumination light beam range 36.

  In the substrate inspection apparatus according to the modified example of FIG. 5, in the orthogonal plane perpendicular to the optical axis AX2 of the imaging system 2, the regular heptagonal vertex centered on the optical axis AX2 is arranged so as to satisfy the conditional expression (4). Seven illumination systems 1a to 1g are provided. As a result, on the pupil plane of the imaging system 2, the range 35 of scattered light from the minute linear scratch 31 illuminated by any one illumination system 1 and the range 38 of the imaging light beam overlap at least partially. Thus, the minute linear scratch 31 extending along all directions can be reliably detected.

  Similarly, in the case where a plurality of illumination systems 1 are arranged at the vertex positions of odd-numbered regular polygons (regular pentagons, regular pentagons, etc.) with the optical axis AX2 as the center in an orthogonal plane orthogonal to the optical axis AX2 of the imaging system 2 In addition, by satisfying conditional expression (4), it is possible to reliably detect minute linear scratches extending along all directions.

On the other hand, when a plurality of illumination systems 1 are arranged at the vertex positions of an even-numbered regular polygon (regular hexagon, regular octagon, etc.) with the optical axis AX2 as the center in an orthogonal plane orthogonal to the optical axis AX2 of the imaging system 2, imaging is performed. In order to at least partially overlap the range 35 of scattered light from the linear scratch 31 illuminated by any one illumination system 1 and the range 38 of the imaging light beam on the pupil plane of the system 2, the following conditional expression (5) must be satisfied.
Da + Db> θei · sinβ (5)

  In the conditional expression (5), θei is an angle formed by the center position of the two adjacent illumination light beam ranges 36 (and hence the position of the two adjacent illumination systems 1) about the optical axis AX2 of the imaging system 2. That is, for example, when eight illumination systems 1 are arranged at the apex position of a regular octagon, θei = 360/8 = 45 degrees. Conditional expression (5) substantially corresponds to a condition in which the circle 38 indicating the imaging light beam range cannot pass between two adjacent illumination light beam ranges 36.

More generally, when a plurality of illumination systems 1 are arranged at the vertex positions of a polygon (not a regular polygon) around the optical axis AX2 in an orthogonal plane orthogonal to the optical axis AX2 of the imaging system 2, the imaging system 2 In order to at least partially overlap the range 35 of the scattered light from the linear scratch 31 illuminated by any one illumination system 1 and the range 38 of the imaging light beam on the pupil plane of It is necessary to satisfy the following conditional expression (6).
Da + Db> θmi · sinβ (6)

  In conditional expression (6), θmi is the maximum value of the angle formed by the center position of the two adjacent illumination light beam ranges 36 (and hence the position of the two adjacent illumination systems 1) about the optical axis AX2 of the imaging system 2. is there. Conditional expression (6) substantially corresponds to a condition in which the circle 38 indicating the imaging light beam range cannot pass between the two illumination light beam ranges 36 adjacent to each other with the largest interval.

  In the above-described embodiments and modifications, the operation of the substrate inspection apparatus according to the present invention has been described focusing on detection of linear flaws formed on the surface of the substrate. However, in practice, not only linear flaws, but also various other forms of flaws and foreign objects such as various forms of minute objects attached to the substrate can be detected in the same manner. If it is necessary to discriminate scratches formed on the substrate from other foreign matters (such as foreign matter), the image of the substrate surface before cleaning can be compared with the image of the substrate surface after cleaning. good. Further, when the inspection is performed over the entire surface of the substrate or over a wide range, the inspection of the foreign matter may be repeated while relatively moving the substrate to be inspected and the substrate inspection apparatus as the inspection means step by step.

  In the above-described embodiment and modification, a combination of one illumination system and a plurality of imaging systems or a combination of one imaging system and a plurality of illumination systems is employed. However, the present invention is not limited to this, and a configuration in which a plurality of illumination systems and a plurality of imaging systems are combined may be employed. In the above-described embodiment and modification, the substrate is arranged along a plane orthogonal to the optical axis of the illumination system or the optical axis of the imaging system. Various forms are possible.

  In the above-described embodiment, the plurality of imaging systems are arranged at substantially equal distances from the inspection region (the region observed on the substrate). However, the present invention is not limited to this, and in the pupil plane of any one imaging system, the range of scattered light from the foreign object illuminated by the illumination system and the range of the imaging light beam overlap at least partially. A plurality of imaging systems can also be arranged at different distances from the inspection area.

  Further, in the above-described modification, the plurality of illumination systems are arranged at substantially equal distances from the inspection region (the region observed on the substrate). However, the present invention is not limited to this, and on the pupil plane of the imaging system, the range of scattered light from the foreign object illuminated by any one illumination system and the range of the imaging light beam overlap at least partially. A plurality of illumination systems may be arranged at different distances from the inspection region.

  Further, in the above-described embodiments and modifications, the present invention is applied to a substrate inspection apparatus that inspects a scratch on a mask substrate used in a liquid crystal exposure apparatus. However, the present invention is not limited to this, and the present invention can be applied to a substrate inspection apparatus that inspects foreign matters on substrates having various forms. That is, the inspection target is not limited to the light transmission type substrate, but may be a reflection type substrate such as a mirror.

  FIG. 7 is a flowchart showing each step of the mask substrate manufacturing method according to the present embodiment. Referring to FIG. 7, the method for manufacturing a mask substrate according to the present embodiment includes a preparation step S11, a polishing step S12, a cleaning step S13, and an inspection step S14. For example, a material having uniform optical characteristics is required for manufacturing a mask (photomask) substrate used in a liquid crystal exposure apparatus.

  In the preparation step S11, a quartz glass material (ingot) is manufactured by synthesizing quartz as a material having uniform optical characteristics. Specifically, for example, a raw material gas of a silicon compound such as silicon tetrachloride or an organosilicon compound, a combustion-supporting gas such as oxygen, and a gas containing a combustion gas such as hydrogen are ejected from a multi-tube burner to form a flame. A quartz glass material is obtained by reacting in the glass and depositing and melting glass particles on a rotating target.

  As such a method for synthesizing quartz, methods described in JP-A No. 2004-28786, JP-A No. 10-279319, JP-A No. 11-292551, and the like can be used. Further, in the preparation step S11, the quartz glass material is cut into a plate shape. Specifically, a portion to be used as a photomask is cut into, for example, a rectangular plate shape or a disk shape from an ingot created on the target using a band saw or a blade.

  Next, in the polishing step S12, the surface of the plate-like quartz glass cut out through the preparation step S11 is polished by a multi-step process including lapping and polishing. As an apparatus for lapping or polishing the surface of a plate-like quartz glass, a polishing apparatus described in JP 2007-98542 A, JP 2007-98543 A, or the like can be used.

  In the polishing apparatus, a plate-like quartz glass substrate is disposed on a carrier having an opening for holding the outer shape of the plate-like quartz glass. And by sandwiching the top and bottom of the carrier and quartz glass with a surface plate having a polishing surface on the surface in contact with the carrier and quartz glass, by rotating the top and bottom surface plates while contacting the polishing surface and the surface of the quartz glass, Wrapping or polishing. In lapping and polishing, a polishing pad and slurry used for the polishing surface of the surface plate are appropriately selected according to the surface roughness of the quartz glass.

  The fine particles contained in the slurry remain on the surface of the quartz glass substrate that has undergone the polishing step S12. For this reason, in the cleaning step S13, cleaning is performed to remove fine particles adhering to the surface of the quartz glass substrate. Specifically, cleaning can be performed by spraying pressurized water onto the surface of the quartz glass substrate or immersing the quartz glass substrate in a cleaning liquid.

  Lastly, in the inspection step S14, the substrate glass inspection apparatus according to the above-described embodiment or modification is used to inspect foreign matter, particularly scratches on the surface of the quartz glass substrate. Specifically, the quartz glass substrate to be inspected is fixedly supported, and the substrate inspection apparatus as the inspection means is stepped two-dimensionally, and foreign matter is inspected over the entire surface of the quartz glass substrate. Do. Alternatively, a foreign substance is inspected over the entire surface of the quartz glass substrate while the substrate inspection apparatus as the inspection means is fixedly supported and the quartz glass substrate to be inspected is stepped two-dimensionally.

  In addition, a large-sized mask substrate can be obtained by press-molding the quartz glass cut into a plate shape in the preparation step S11 to increase the surface area. For press molding, for example, a graphite mold having a flat press surface is prepared, and after being pressurized through the mold in a state of being heated to a temperature higher than the crystallization temperature of quartz glass under an inert gas atmosphere, cooling is performed. Is done. As such a press molding method, a method described in JP-A No. 2004-307266 can be used. The above-described polishing step S12, cleaning step S13, and inspection step S14 are performed on the press-molded quartz glass substrate.

It is a figure showing roughly composition of a substrate inspection device concerning an embodiment of the present invention. It is a figure which shows typically a mode that scattered light generate | occur | produces from the linear flaw by receiving irradiation of illumination light. It is a figure explaining the conditions required in order to detect a linear flaw in this invention. It is a figure explaining conditions required in order to detect a linear crack in the substrate inspection device of this embodiment. It is a figure which shows roughly the structure of the board | substrate inspection apparatus concerning the modification which arrange | positions several illumination system in the vertex position of the polygon centering on the optical axis of one imaging system. It is a figure explaining conditions required in order to detect a linear crack in the board | substrate inspection apparatus concerning the modification of FIG. It is a flowchart which shows each process of the manufacturing method of the mask substrate concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illumination system 2 Imaging system 11 Halogen lamp 12 Ellipsoidal mirror 13 Condensing optical system 30 Substrate 31 Linear scratch

Claims (9)

In a board inspection device that inspects foreign substances on a board,
An illumination system for illuminating the substrate;
A plurality of imaging systems for dark field observation of the area on the substrate illuminated by the illumination system;
The plurality of imaging systems are arranged such that the range of scattered light from the foreign object illuminated by the illumination system and the range of the imaging light beam overlap at least partially on the pupil plane of any one imaging system. A board inspection apparatus. The plurality of imaging systems are arranged at a vertex position of a polygon around the optical axis of the illumination system in an orthogonal plane orthogonal to the optical axis of the illumination system,
The diameter of the illumination light beam range on the pupil plane of the illumination system is Da, the diameter of the imaging light beam range on the pupil plane of the imaging system is Db, and the positions of two adjacent imaging systems on the orthogonal plane are the illuminations. When the maximum value of the angle formed around the optical axis of the system is θmc, and the angle between the optical axis of the illumination system and the optical axis of the imaging system is α,
Da + Db> θmc · sinα
The substrate inspection apparatus according to claim 1, wherein the following condition is satisfied. The plurality of imaging systems are arranged at vertex positions of regular polygons with even angles around the optical axis of the illumination system in an orthogonal plane orthogonal to the optical axis of the illumination system,
The diameter of the illumination light beam range on the pupil plane of the illumination system is Da, the diameter of the imaging light beam range on the pupil plane of the imaging system is Db, and the positions of two adjacent imaging systems on the orthogonal plane are the illuminations. When the angle formed around the optical axis of the system is θec, and the angle formed between the optical axis of the illumination system and the optical axis of the imaging system is α,
Da + Db> θec · sin α
The substrate inspection apparatus according to claim 1, wherein the following condition is satisfied. The plurality of imaging systems are arranged at the vertex positions of an odd-numbered regular polygon centered on the optical axis of the illumination system in an orthogonal plane orthogonal to the optical axis of the illumination system,
The diameter of the illumination light beam range on the pupil plane of the illumination system is Da, the diameter of the imaging light beam range on the pupil plane of the imaging system is Db, and the positions of two adjacent imaging systems on the orthogonal plane are the illuminations. When the angle formed around the optical axis of the system is θoc and the angle formed between the optical axis of the illumination system and the optical axis of the imaging system is α,
Da + Db> θoc · sin α / 2
The substrate inspection apparatus according to claim 1, wherein the following condition is satisfied. In a board inspection device that inspects foreign substances on a board,
A plurality of illumination systems for illuminating the substrate;
An imaging system for dark field observation of the area on the substrate illuminated by the plurality of illumination systems;
The plurality of illumination systems are arranged on the pupil plane of the imaging system so that a range of scattered light from a foreign object illuminated by any one illumination system and a range of imaging light beams at least partially overlap each other. A board inspection apparatus. The plurality of illumination systems are arranged at vertex positions of a polygon around the optical axis of the imaging system in an orthogonal plane orthogonal to the optical axis of the imaging system,
The diameter of the range of the illumination light beam on the pupil plane of the illumination system is Da, the diameter of the range of the imaged light beam on the pupil plane of the imaging system is Db, and the positions of two adjacent illumination systems on the orthogonal plane are the imaging When the maximum value of the angle formed around the optical axis of the system is θmi, and the angle between the optical axis of the illumination system and the optical axis of the imaging system is β,
Da + Db> θmi · sinβ
The board inspection apparatus according to claim 5, wherein the following condition is satisfied. The plurality of illumination systems are arranged at vertex positions of regular polygons with even angles around the optical axis of the imaging system in an orthogonal plane orthogonal to the optical axis of the imaging system,
The diameter of the range of the illumination light beam on the pupil plane of the illumination system is Da, the diameter of the range of the imaged light beam on the pupil plane of the imaging system is Db, and the positions of two adjacent illumination systems on the orthogonal plane are the imaging When the angle formed around the optical axis of the system is θei, and the angle formed between the optical axis of the illumination system and the optical axis of the imaging system is β,
Da + Db> θei · sinβ
The board inspection apparatus according to claim 5, wherein the following condition is satisfied. The plurality of illumination systems are arranged at the apex positions of odd-numbered regular polygons around the optical axis of the imaging system in an orthogonal plane orthogonal to the optical axis of the imaging system,
The diameter of the range of the illumination light beam on the pupil plane of the illumination system is Da, the diameter of the range of the imaged light beam on the pupil plane of the imaging system is Db, and the positions of two adjacent illumination systems on the orthogonal plane are the imaging When the angle formed around the optical axis of the system is θoi and the angle formed between the optical axis of the illumination system and the optical axis of the imaging system is β,
Da + Db> θoi · sinβ / 2
The board inspection apparatus according to claim 5, wherein the following condition is satisfied. In the mask substrate manufacturing method,
The manufacturing method characterized by including the test | inspection process which test | inspects the foreign material of the said board | substrate for masks using the board | substrate inspection apparatus of any one of Claims 1 thru | or 8.

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