TWI461831B - Method of manufacturing a glass substrate for a mask blank, method of manufacturing a mask blank and method of manufacturing a photomask for exposure - Google Patents

Description

Method for producing glass substrate for mask base, method for manufacturing photomask substrate, and method for producing exposure mask

The present invention relates to a method for producing a glass substrate for a mask base, a method for producing a mask substrate, and a method for producing an exposure mask.

In recent years, with the miniaturization of semiconductor elements, in the photolithography technique, short-wavelength light such as an ArF excimer laser (exposure wavelength of 193 nm) has been used as an exposure light. Moreover, in the technical field of the exposure mask used in the photolithography technology and the mask base for manufacturing the exposure mask, the shading which can shield the short-wavelength exposure light is also rapidly performed. The development of a film and a phase shifting film that changes the phase has been proposed for various film materials.

Here, it is required that the inside of the glass substrate for a mask base and the synthetic quartz glass substrate for manufacturing the glass substrate for the mask base be free from defects such as foreign matter or bubbles. Patent Document 1 discloses a defect detecting method in which a fluorescent light generated by an internal defect of a glass substrate is detected when an inspection light having a wavelength of 200 nm or less is introduced into a glass substrate, thereby detecting a glass substrate. Internal defects (foreign objects or bubbles, etc.).

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2007-86050

However, it has been found that even in the case of the glass substrate which is determined to have no internal defects by the above-described defect detecting method, there are cases where minute defects remain particularly in the vicinity of the front surface and the back surface. The inventor of the case investigated the cause and found out the following facts.

1 is an explanatory view of a defect inspection step of a conventional glass substrate for a reticle base, and FIG. 2 is a perspective view of the glass substrate 10 of FIG. 1. In FIGS. 1 and 2, reference numeral 10 denotes a glass substrate to be inspected, and the glass substrate 10 includes two main surfaces 11, 12, and four end faces 13, 14, 15, 16. Chamfered faces 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b are formed at corners where the two main surfaces 11, 12 intersect the four end faces 13, 14, 15, 16.

The inspection light L is vertically irradiated from the left side in the drawing with respect to the end surface 13 and introduced into the inside of the glass substrate 10. The inspection light L is light having a width (upper and lower width) t _L which is slightly larger than the thickness tg of the glass substrate 10 and substantially substantially parallel. Therefore, the inspection light L is actually introduced into the inside of the glass substrate 10 through the end surface 13 and the chamfered surfaces 13a and 13b. Further, the lateral width of the inspection light L (the width in the direction parallel to the front surface and the back surface) also has a width substantially equal to the above-described vertical width t _L . Therefore, the entire glass substrate is inspected by introducing the inspection light to the entire glass substrate by moving the glass substrate in a direction parallel to the front surface and the back surface.

Here, the inspection light L is incident substantially perpendicularly from the end surface 13, but the light introduced into the interior by the chamfered surfaces 13a and 13b is incident at an angle of about 45° with respect to the chamfered surfaces, and passes through the glass substrate 10 Within the area S1, S2. Therefore, it is considered that when the light is incident from the chamfered surfaces 13a and 13b, the light is refracted and reflected by the same surface, and is compared with the intensity of the inspection light which is incident perpendicularly from the end surface 13 and passes through other regions. The intensity of the inspection light incident on the equal surface and passing through the regions S1, S2 becomes quite weak. As a result, it is considered that the intensity of the inspection light irradiated to the defects Ka, Kb, and the like located in the regions S1 and S2 is insufficient, and the fluorescence generated by the minute internal defects is also insufficient.

The present invention has been developed based on the above-described background, and an object of the invention is to provide a method for producing a glass substrate for a mask base, a method for producing a mask substrate, and a method for producing an exposure mask, which are used for manufacturing a glass substrate for a mask base. At this time, even minute internal defects in the vicinity of the main surface of the glass substrate for the reticle base can be detected without fail, whereby the internal defects of substantially all the regions can be favorably detected to obtain a defect-free product.

The methods for solving the above problems are listed below.

(1) A method for producing a glass substrate for a mask base, comprising the steps of: preparing a substrate for preparing a mask base having a thin plate shape having two main surfaces and four end faces; and detecting a defect a step of detecting an internal defect by introducing inspection light of substantially parallel light having a wavelength of 200 nm or less from one end into the glass substrate; and the defect inspection step is performed by tilting the inspection light toward a main surface side from one end surface to be introduced into the glass substrate Further, the inspection light is introduced into the glass substrate by tilting the inspection light toward the main surface side facing the one main surface from the end surface facing the one end surface, thereby inspecting the internal defect of the glass substrate by using the inspection light. The presence or absence of the generated fluorescence, and the selection of the glass substrate which did not detect the fluorescence generated by the internal defect.

(2) The method for producing a glass substrate for a reticle base according to (1), wherein the glass substrate has a chamfered surface formed at a corner portion where the two main surfaces intersect the four end faces.

(3) The method for producing a glass substrate for a mask base according to (1) or (2), wherein, in the defect inspection step, the inspection light is introduced in addition to the one end surface and the end surface opposite to the one end surface, thereby further inspecting The light is introduced into the glass substrate from either end surface without inclination with respect to all the main surfaces, and the presence or absence of the fluorescence generated by the above internal defects is examined.

(4) The method for producing a glass substrate for a mask base according to (1) or (2), wherein the inspection light system introduced into the glass substrate has divergent light having a specific divergence angle.

(5) The method for producing a glass substrate for a mask base according to (4), wherein the inspection light is converted into divergent light from the end surface into the glass substrate by a concave lens or a concave mirror.

(6) The method for producing a glass substrate for a mask base according to (5), wherein the concave lens is disposed in a cylindrical lens before the end surface.

(7) The method for producing a glass substrate for a mask base according to (5), wherein the concave mirror is disposed on a cylindrical concave mirror before the end surface.

(8) A method of manufacturing a reticle substrate, comprising the step of: manufacturing a reticle substrate manufactured by the method for producing a glazing substrate for a reticle substrate according to any one of (1) to (7) The main surface of the glass substrate forms a film for pattern formation.

(9) A method of producing an exposure mask, comprising the steps of: forming an exposure film on the film for pattern formation of a mask substrate manufactured by the method for manufacturing a mask base according to (8) Fine pattern.

(10) A method of manufacturing a reticle substrate, comprising: a substrate preparation step of preparing a thin glass substrate for a reticle base having two main surfaces and four end faces; and a film forming step, a film for forming a pattern on a main surface of the glass substrate; and a defect inspection step of inspecting an internal defect by introducing inspection light of substantially parallel light having a wavelength of 200 nm or less from the one end toward the glass substrate; and the defect inspection step is performed for inspection The light is inclined toward one main surface side and introduced into the glass substrate from one end surface, and further, the inspection light is inclined toward the main surface side facing the one main surface, and is introduced into the glass substrate from the end surface facing the one end surface. Thereby, the presence or absence of the fluorescent light generated by the internal defects of the glass substrate is inspected by the inspection light, and the mask base on which the fluorescent light generated by the internal defects is not detected is selected.

(11) A method of manufacturing an exposure mask, comprising the steps of: preparing a substrate, preparing a thin glass substrate for a mask base comprising two main surfaces and four end faces; and forming a film, a film for forming a pattern on a main surface of the glass substrate; a fine pattern forming step of forming a fine pattern for exposure on the film; and a defect inspection step of introducing a substantially parallel wavelength of 200 nm or less from one end toward the glass substrate The inspection light of the light is used to inspect the internal defect; and the defect inspection step is such that the inspection light is inclined toward a main surface side and introduced into the glass substrate from one end surface, thereby causing the inspection light to face the main surface side opposite to the one main surface. The light is inclined from the end surface facing the one end surface into the glass substrate, whereby the presence or absence of the fluorescent light generated by the internal defect of the glass substrate is inspected by the inspection light, and the occurrence of the internal defect is not detected. Fluorescent exposure mask.

(12) A method for producing a glass substrate for a reticle base, comprising the steps of: preparing a substrate, preparing a glass substrate for a reticle base comprising two main surfaces and four end faces; and detecting a defect a step of inspecting an internal defect by introducing inspection light having a wavelength of 200 nm or less from one end toward the glass substrate; the defect inspection step uses diverging light having a specific divergence angle as inspection light to cause inspection light to reach the glass substrate to be inspected The entire specific area is used to check the presence or absence of fluorescence generated by internal defects, and a glass substrate in which no fluorescence generated by internal defects is detected is selected.

(13) The method for producing a glass substrate for a mask base according to (12), wherein the glass substrate has a chamfered surface formed at a corner portion where the two main surfaces intersect the four end faces.

(14) The method for producing a glass substrate for a mask base according to (12) or (13), wherein the inspection light has a divergence angle reaching the entire specific region when being introduced into the glass substrate from one end surface.

(15) The method for producing a glass substrate for a mask base according to (12) or (13), wherein the inspection light has a divergence angle when introduced into the glass substrate from one end surface: by the one end surface and the opposite end surface thereof In a specific region in which the intermediate surface set between the end faces is divided into two, the entire region of the region close to the side of the one end face is not reached, and the entire region of the region away from the side of the one end face is reached.

(16) The method for producing a glass substrate for a reticle base according to any one of (12) to (15), wherein the inspection light is introduced into the glass substrate from one end surface to check the presence or absence of fluorescence, and then the above The inspection light is introduced into the glass substrate from the end surface facing the one end surface to check the presence or absence of the fluorescence.

(17) The method for producing a glass substrate for a reticle base according to any one of (12), wherein the inspection light is introduced from the end surface to the glass substrate by a concave lens or a concave mirror to convert the parallel light into divergent light. Insider.

(18) The method for producing a glass substrate for a mask base according to (17), wherein the concave lens is disposed in a cylindrical lens before the end surface.

(19) The method for producing a glass substrate for a mask base according to (17), wherein the concave mirror is disposed on a cylindrical concave mirror before the end surface.

(20) A method of manufacturing a reticle substrate, comprising the step of: manufacturing a reticle substrate manufactured by the method for producing a glazing substrate for a reticle substrate according to any one of (12) to (19) The main surface of the glass substrate forms a film for pattern formation.

(21) A method of producing an exposure mask, comprising the steps of: forming an exposure film on a film for pattern formation of a mask substrate manufactured by the method for manufacturing a mask base according to (20) Fine pattern.

(22) A method of manufacturing a reticle substrate, comprising: a substrate preparation step of preparing a thin glass substrate for a reticle base having two main surfaces and four end faces; and a film forming step, a film for forming a pattern on a main surface of the glass substrate; and a defect inspection step of inspecting an internal defect by introducing inspection light having a wavelength of 200 nm or less from one end toward the glass substrate; and the defect inspection step uses divergent light having a specific divergence angle As the inspection light, the inspection light reaches the entire specific region to be inspected in the glass substrate to check the presence or absence of the fluorescent light generated by the internal defect, and the mask base on which the fluorescence generated by the internal defect is not detected is selected.

(23) A method of manufacturing an exposure mask, comprising the steps of: preparing a substrate, preparing a thin glass substrate for a mask base comprising two main surfaces and four end faces; and forming a film, a film for forming a pattern on a main surface of the glass substrate; a fine pattern forming step of forming a fine pattern for exposure on the film; and a defect inspection step of introducing inspection light having a wavelength of 200 nm or less from one end toward the glass substrate to inspect Internal defect; and the defect inspection step uses divergent light having a specific divergence angle as inspection light, and the inspection light reaches the entire specific area to be inspected in the glass substrate to check the presence or absence of fluorescence generated by the internal defect. An exposure mask that does not detect fluorescence generated by internal defects is selected.

In the inspection step, the inspection light of substantially parallel light is inclined from one end surface of the glass substrate toward the main surface side and introduced into the glass substrate, and the inspection light is directed from the end surface facing the one end surface to the one end. The main surface is inclined toward the main surface side and introduced into the glass substrate, whereby the inspection light is easily reached to a specific region including the vicinity of the surface of the glass substrate, so that it is easy to even detect the small vicinity of the main surface of the glass substrate for the reticle base. Internal defects.

The divergent light having a divergence angle reaching the entire specific area to be inspected is used as the inspection light introduced into the glass substrate from one end surface, whereby the inspection light introduced into the inside of the glass substrate is easily reached to the vicinity of the main surface of the glass substrate Specific area.

Depending on the shape of the glass substrate to be inspected, there may be a region where the inspection light from both the one end surface side and the opposite end surface side does not reach, but by any one of the main surfaces without tilting The inspection light is introduced into the end surface, so that the inspection light can be surely reached to the entire specific area to be inspected.

Further, the inspection light is made to have divergent light having a specific divergence angle, and the inspection light is introduced from both the one end surface side and the opposite end surface side, whereby the inspection light can be surely reached to the entire specific area to be inspected. .

(Embodiment 1)

3 is an explanatory view of an internal defect inspection step in the method of manufacturing a glass substrate for a reticle base according to Embodiment 1 of the present invention, FIG. 4 is an enlarged view of a portion A of FIG. 3, and FIG. 5 is a view for implementing the present invention. FIG. 6 is an explanatory view showing a configuration of an internal defect inspection step in the method for producing a glass substrate for a reticle base according to the first embodiment, and FIG. 6 is an explanatory view of defect detection. Hereinafter, a method of manufacturing a glass substrate for a mask base according to Embodiment 1 of the present invention, a method for producing a mask base, and a method for producing an exposure mask will be described with reference to the drawings. In addition, the glass substrate for a reticle base which is the object to be inspected in the internal defect inspection step of the first embodiment is the same as the glass substrate for the reticle base which is the object of the inspection method for the glass substrate for the reticle base described above. The same parts are denoted by the same symbols for explanation.

The method for producing a glass substrate for a reticle base according to the first embodiment includes (1) a grinding step of a glass substrate for a reticle substrate to be inspected for internal defects, (2) a defect inspection step for a glass substrate for a reticle base, and (3) a polishing step of a glass substrate for a mask substrate. Further, in the method of manufacturing a mask base according to the first embodiment, the step of manufacturing the mask base is performed on the glass substrate for a mask base manufactured by the above steps (1) to (3). Further, in the method for producing an exposure mask according to the first embodiment, the step of manufacturing the exposure mask (5) is performed on the mask substrate manufactured by the step (4). In the above-described steps, the greatest feature of the first embodiment is the method of inspecting the internal defects of the glass substrate for the mask base used in the inspection step of the internal defects of the glass substrate for the mask base, and other steps are generally known. In the following, the following description of the well-known steps will be given as a minimum, and the defect inspection method of the glass substrate for a reticle base will be mainly described. (2) Internal defect inspection step of the glass substrate for the mask base, even for the (3) glass substrate after the polishing step of the glass substrate for the mask base, and (4) the mask substrate after the manufacturing step of the mask substrate Or (5) the exposure mask after the manufacturing step of the exposure mask is used, and the accuracy of the internal defect inspection is not substantially different. However, if the step is performed after the polishing step of the glass substrate for the mask base (3), the manufacturing step of the mask substrate, and (5) the manufacturing step of the exposure mask, Also, all the glass substrates including the defective products having internal defects are subjected to polishing and film formation, so that a large waste is caused. Therefore, it is preferred to carry out the steps before the grinding step of (3). Further, when focusing on the case where the internal defect is more reliably found, the glass substrate for the reticle substrate on which the polishing step of the glass substrate is completed, the reticle substrate on which the film for pattern formation is formed on the glass substrate, and the exposure Use the reticle for the internal defect inspection step.

(1) Grinding step of a glass substrate for a mask base to be an internal defect inspection target

A synthetic quartz glass ingot prepared by a well-known method (for example, refer to Japanese Patent Laid-Open No. Hei 8-31723, No. 2003-81654, etc.), cut out about 152.4 mm × about 152.4 mm × about A plate-shaped body of 6.85 mm to obtain a glass substrate of synthetic quartz. The glass substrate includes two major surfaces opposite to each other and four end faces orthogonal to the two major surfaces.

After chamfering the corner portion where the main surface and the end surface of the glass substrate intersect, the end surface into which the inspection light is introduced is mirror-polished so that the inspection light can be introduced into the inside of the glass substrate to obtain the glass substrate 10 for the mask base. The glass substrate 10 is the same as the glass substrate for a mask base shown in FIGS. 1 and 2, and includes two main surfaces 11, 12, four end faces 13, 14, 15, 16 and eight chamfered faces. 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b. Here, the surface roughness Ra (Average Roughness) of the end surface (one end surface) 13 into which the inspection light is introduced and the end surface 14 opposed thereto are set to be about 0.03 μm or less. Further, since all of the four end faces are mirror-polished by the polishing step of the mask base, the other end faces 14, 15, 16 can also be mirror-polished at the stage of the grinding step. The reticle substrate thus obtained is supplied to the glass substrate 10 to the next step, that is, the inspection step of the internal defect.

(2) Defect inspection procedure for the glass substrate for the mask base

This step is a step of inspecting the presence or absence of internal defects of the reticle base glass substrate 10 obtained as described above by the defect inspection method described below. Hereinafter, a method of inspecting the glass substrate for a reticle base used in this step will be described. In this case, only the inspection light is incident on the main surface 11 side from the end surface 13 side, and the inspection light is incident from the end surface 14 side toward the main surface 12 side, and the inspection light does not reach the entire specific area. In the case where the inspection light is spread over the entire specific region, the inspection light is incident from the end surface 13 side without obliquely with respect to the main surfaces 11, 12.

In Fig. 3, first, the inspection light L of substantially parallel light having a divergence angle of 2 mrad is introduced into the glass substrate 10 from the end surface 13 of the glass substrate 10 to detect the fluorescence generated by the defect at this time.

In other words, the inspection light L is incident on the main surface 11 side in a direction oblique to the main surface 11 by the inclination angle θg. In this case, it is necessary to set the inclination angle θg to be incorporated into the glass substrate by the corner portion where the inspection surface L introduced into the glass substrate 10 intersects the chamfered surfaces 13a and 13b. In the case of L1 and L2, the light ray L1 is located on the intersection line E of the boundary surface E on the main surface 11 side of the specific region and the boundary surface B on the end surface 13 side of the specific region, or is closer to the end surface 13 side, and the light ray L2 It is located at the intersection line H of the corner portion where the end surface 13 intersects the chamfered surface 13a and the corner portion where the end surface 14 intersects the chamfered surface 14a, and the boundary surface D of the end surface 14 side of the specific region, or more On the side of the end face 14. When the light beams L1 and L2 do not satisfy the above conditions, even if the inspection light is incident on the end surface 13 side (all the end surface sides are the same) without obliquely incident on the main surfaces 11 and 12, the inspection light cannot be spread over all the specific regions, and thus the inspection light cannot be performed. Ensure the inspection of the actual internal defects. Further, when the inspection light L is introduced into the glass substrate 10 from the end surface 13, the angle of the light is changed by a specific amount due to the difference in refractive index between the air and the glass substrate 10. The inclination angle θg of the inspection light L is an inclination angle of the inspection light before entering the glass substrate 10, and is set in consideration of the fact that the angles of the light beams L1 and L2 are changed when being introduced to the glass substrate 10.

Next, the inspection light L is introduced into the glass substrate 10 from the end surface 14 of the glass substrate 10 to detect the fluorescence generated by the defect at this time.

In other words, the inspection light L is incident on the main surface 12 side in a direction inclined by the inclination angle θg with respect to the main surface 12. In this case, it is necessary to set the inclination angle θg in such a manner that the light introduced into the glass substrate 10 and the corner portion where the end surface 14 intersects the chamfered surfaces 14a and 14b is introduced into the glass substrate. In the case of L3 and L4, the light ray L4 is located on the intersection line Df of the boundary surface F on the main surface 12 side of the specific region and the boundary surface D of the end surface 14 side of the specific region, or on the side closer to the end surface 14, and the light ray L3 It is located at the intersection line J of the corner surface where the end surface 13 intersects the chamfered surface 13b and the boundary surface J of the corner portion where the end surface 14 intersects the chamfered surface 14b, and the boundary surface B of the end surface 13 side of the specific region, or more On the side of the end face 13. When the light beams L3 and L4 do not satisfy the above conditions, even if the inspection light is incident from the end surface 13 side (all the end surface sides are the same) with respect to the main surfaces 11 and 12 without obliquely tilting, the inspection light cannot be spread over all the specific regions, and thus cannot be performed. Ensure the inspection of the actual internal defects.

Further, the inspection light L is introduced into the glass substrate 10 from either end surface (the end surface 13 in FIG. 3) of the glass substrate 10 to inspect the defective light generated by the defect at this time. That is, the inspection light L is incident on the main surfaces 11 and 12 without being inclined. At this time, when the light beams introduced into the glass substrate 10 at the corners where the end faces 13 and the chamfered surfaces 13a and 13b intersect each other in the inspection light L introduced into the glass substrate 10 are L5 and L6, the light ray L5 passes. On the boundary surface H, the light ray L6 passes through the boundary surface J, so that the inspection light L reaches the entire area sandwiched between the boundary surface H and the boundary surface J in the glass substrate 10. By adopting such a method, the inspection light can be spread over the entire specific region surrounded by the boundary faces B, D, E, and F in the glass substrate 10.

Here, the range of the thickness direction of the reticle base of the specific region (the direction between the main surface 11 and the main surface 12) is not necessarily required to cause the inspection light to reach the entire region in the thickness direction. The reason is that when the defect inspection step is performed after the grinding step is finished, in the subsequent grinding step, a certain amount of glass is cut in the thickness direction from both sides by grinding the main surfaces 11 and 12 (Fig. 4 Part 11a), so even if there is an internal defect in the area to be cut, the internal defect has been removed in the glass substrate for the reticle base after completion. However, in consideration of the fact that the main surface on the side where the film for pattern formation is formed and the main surface on the opposite side thereof are slightly different in amount, the two main surfaces are not completely flat, etc., it is preferable to inspect the light in the thickness direction. The area to be reached has a slight margin (the surface exposed after the grinding step on the main surface 11 side, the virtual main surface with a slight margin is the boundary surface E, the surface exposed after the grinding step on the main surface 12 side, slightly The virtual main surface of the margin is the boundary surface F). For example, in the case of a glass substrate for a reticle base having a size of about 152 mm × 152 mm on the main surface (including the size of the chamfered portion), the thickness (thickness in the thickness direction) is 6.85 mm after the end of the grinding step. Grinding is carried out to a target of 6.35 mm. In consideration of the above-described margin, it is sufficient that the inspection light reaches a region having a thickness of at least 6.4 mm based on the center of the substrate in the thickness direction. In other words, in the glass substrate after the completion of the grinding step, the portion outside the center of the substrate in the thickness direction is more than 6.4 mm, and is removed in the subsequent polishing step. Therefore, even if the portion is excluded from the inspection. There is no problem outside the area.

On the other hand, the range of the main surface side of the specific region is a region where the transfer pattern is formed on the film when the photomask substrate is fabricated using the glass substrate for the reticle base and the exposure reticle is formed based on the reticle substrate. As long as the minimum coverage is enough. This is because the exposure mask is formed on the glass substrate for the reticle base, and is placed on the reticle stage of the exposure apparatus, and the pattern is transferred to the transfer target (wafer or the like) to form a turn. The exposed light of the areas on the outer surfaces 11 and 12 on the outer side of the printed pattern area is shielded by the film, so that even if there is an internal defect in the area, the transfer target is not adversely affected.

For example, in the case where the main surface has a glass substrate for a mask base having a size of about 152 mm × 152 mm, the region where the transfer pattern is formed is usually an area of 132 mm × 132 mm on the basis of the center of the mask base. In this case, the boundary surface B of the specific region is set at least at a distance from the center of the reticle base toward the end surface 13 at a distance of 66 mm from the center of the reticle base, in parallel with the end surface 14 and from the reticle. The boundary surface D of the specific region may be set at a distance of 66 mm from the center of the base toward the end surface 14. Further, the exposure mask is provided on the mask stage of the exposure apparatus in such a manner that the main surface on the side where the film is not formed faces the light source side of the exposed light. Therefore, even if light exposed in an area outside the specific area can be irradiated to the inside of the glass substrate 10, if there is an internal defect, fluorescence is generated therefrom. When the internal defect is located in the vicinity of the boundary faces B and D of the specific region, the fluorescent light emitted from the place may adversely affect the pattern transfer toward the transfer object. In consideration of such a case, it is preferable to set the specific region with a margin to a region inside the 142 mm × 142 mm with respect to the center of the mask base. If it is further made to have a margin, it is more preferable to set the specific area to an area inside, for example, 146 mm × 146 mm.

In consideration of the above, when a glass substrate for a reticle base of about 152 mm × 152 mm × 6.35 mm is manufactured, the specific area to be inspected in the internal defect inspection step is at least 132 mm × 132 mm × 6.4 based on the center of the substrate. The inside of the glass substrate of mm can be used. Further, when a more accurate internal defect inspection is required, it is preferable to set the specific region to the inside of the glass substrate with the substrate center as a reference of 142 mm × 142 mm × 6.45 mm. Thereby, the inspection light L can be spread over the area where the transfer pattern is formed in the glass substrate 10, and by detecting the defective light generated at this time, the defect detection can be performed relatively easily.

In the above embodiment, the inclination angle θc is specifically as follows.

‧Check light: ArF excimer laser light (exposure wavelength: 193 nm)

‧Material of glass substrate 10: Synthetic quartz glass

‧Refractive index: 1.52 (exposure wavelength: at 193 nm)

‧ size of glass substrate 10

Vertical and horizontal: about 152 × 152mm,

Thickness tg: 6.4 mm (target thickness after grinding step is 6.35 mm + error range)

The amount of chamfer m (refer to Figure 4): 0.6mm

‧Specific area: 132mm × 132mm × 6.4mm (based on the center of the substrate)

‧Check the tilt angle of light θg: 2.4°

When the fabrication of the glass substrate for the mask base is completed as described above (after the completion of the polishing step), the aspect ratio is about 152 mm × 152 mm × 6.35 mm, and when the amount of chamfering m is 0.6 mm, the inspection light should be minimized. When the specific region is 132 mm × 132 mm × 6.4 mm, the inclination angle θg may be 2.4°. Further, when the substrate size is the same and the specific region where the inspection light is to be reached is 142 mm × 142 mm × 6.45 mm, the inclination angle θg may be 4.8°.

Next, a device configuration for carrying out the defect inspection step of the first embodiment will be described with reference to Fig. 5, and a defect inspection step in the method for manufacturing a glass substrate for a mask base according to the first embodiment of the present invention will be described in more detail. .

In Fig. 5, reference numeral 20 is a defect inspection device for a glass substrate. The glass substrate defect inspection device 20 includes a laser device 21 for generating inspection light L and irradiated to a glass substrate, and an XYZ stage 22 on which the glass substrate 10 is placed and oriented in the X direction, the Y direction, and the Z direction. Moving separately and transmitting its position information; a CCD (Charge Coupled Device) camera 23 detecting defective light generated in the glass substrate 10; and a computer 27 inputting image information from the CCD camera 23 from The location information of the XYZ platform 22, etc., and the specific processing.

The laser device 21 is disposed on the side of the end surface 13 of the glass substrate 10 placed on the XYZ stage 22. Further, as shown by a broken line, one of them may be provided on the side opposite to the end surface 14 facing the end surface 13. The inspection light L emitted from the laser device 21 is introduced into the glass substrate 10 through the end surface 13 and the end surface 14. The inspection light beam shape emitted from the laser device 21 is a pulse-shaped ArF excimer laser light (wavelength: 193 nm) having a shape of 7.0 mm × 4.0 mm, a power of 6 mJ, and a frequency of 400 Hz.

The XYZ stage 22 can mount the glass substrate 10 and move it in the XYZ direction, and can also tilt the glass substrate 10 to move and tilt the glass substrate 10 to a desired position, and send the position to the computer 27. Information person. In other words, in order to incline the inspection light L with respect to the main surfaces 11 and 12 of the glass substrate 10 at an inclination angle θg°, it can be realized by inclining the glass substrate 10 side. Further, the laser device 21 may be configured such that the inspection light L can be inclined with respect to the main surfaces 11 and 12 of the glass substrate 10.

When the defect inspection is performed, the glass substrate 10 is placed at the position where the inspection is started, and the glass substrate 10 is inclined so as to satisfy the above-described condition of the inclination angle θg so that the inspection light L is incident on the main surface 11 side, and secondly, by The laser device 21 introduces the inspection light L into the glass substrate 10, and images the fluorescent light Lkc and Lkd at this time by the CCD camera 23, and transmits the image information and the position information to the computer 27 for storage. . Next, the XYZ stage 22 is driven to move the glass substrate 10 in the Y direction by a distance corresponding to the width of the inspection light L, and the inspection light L is irradiated in the same manner, and the image of the fluorescent light Lkc and Lkd at this time is captured by the CCD camera 23. And sending the above image information together with the location information to the computer 27. By repeating this operation, the inspection light L is introduced from all the ends of the end face 13 to the other end.

Next, the glass substrate 10 is moved on the XYZ stage 22 so that the end surface 14 faces the laser device 21 side, and the inclination angle θg satisfying the above condition is inclined so that the inspection light L is incident on the main surface 12 side. Then, the same operation as in the case of introduction from the end face 13 is repeated, and the inspection light L is introduced from all the ends of the end face 14 to the other end. Finally, the glass substrate 10 is moved on the XYZ stage 22 in such a manner that the end face 13 faces the side of the laser device 21, so that the inspection light is substantially parallel and not inclined with respect to the main surfaces 11, 12, and the same operation is repeated, and from the end face 13 The inspection light L is introduced in all areas from one end to the other end.

By the series of steps, the inspection light L is irradiated to all areas in the glass substrate 10, and the image of the fluorescence in all areas in the glass substrate 10 is stored. In addition, the inspection light that is inclined toward the main surface 11 side is introduced from the end surface 13 side, and the inspection light is introduced from the end surface 14 side after the image storage step of the fluorescent light is completed, and if the XYZ stage 22 is not moved at all, By rotating the glass substrate 10 by a robot or the like (the glass substrate 10 itself is rotated such that the main surface 12 is the surface and the end surface 14 faces the laser device 21 side), the adjustment position and the tilt angle can be omitted. Work, so better.

The CCD camera 23 is disposed on the side of the main surface 11 which is one of the front surface and the back surface (above the figure, but when the glass substrate 10 is reversed, becomes the side of the main surface 12) for making An image formed from information of light emitted from the glass substrate 10. That is, the fluorescent light Lkc, Lkd generated by the internal defects of the glass substrate 10 is detected, an image of the fluorescent light is captured, and the image information is transmitted to the computer 27. Further, in the first embodiment, a so-called black and white camera is used as the CCD camera 23.

The computer 27 inputs an image from the CCD camera 23, and performs image processing on each position of the glass substrate 10 in the Y direction. The position of the glass substrate 10 in the Y direction is based on the position of the glass substrate 10 in the X direction. The relationship between the light beams Lkc, Lkd, and Lg received by the CCD camera 23 is analyzed. That is, when the light amount of the light Lkc, Lkd, Lg has a partial light amount equal to or greater than a certain threshold value, the computer 27 determines that the internal defects Kc, Kd have emitted the partial light amount Lkc, Lkd above the specific threshold value, Therefore, the types of internal defects Kc and Kd (local veins, contents, foreign matter) and the positions of the internal defects Kc, Kd are determined based on the shape of the partial light amount Lkc, Lkd emitted by the internal defects Kc, Kd, and the like. (The positions in the X direction and the Y direction in the glass substrate 10) are collectively specified and detected.

For example, when local veins or contents are present as the internal defects Kc in the glass substrate 10, the local veins or contents are caused by introducing ArF excimer laser light from the laser irradiation device 21 to the glass substrate 10. As shown in FIG. 6(A), a partial light amount Lkc of a specific threshold value (1000 counts) or more is emitted, and a region other than the local vein or the content of the synthetic quartz glass substrate 4 emits light Lg. The computer 27 performs image processing on the light Lkc and Lg received by the CCD camera 23 and analyzes it, and determines the internal defect Kc as a local vein or according to the shape of the partial light amount Lkc above the specific threshold value. The foreign matter is considered to be a position where the local vein or the content exists at a portion of the light amount Lkc above the specific threshold value, so that the local vein or the content is detected together with the position. Here, in the case of FIG. 6(A), the horizontal axis represents the position of the glass substrate 10 in the X direction, and the vertical axis represents the amount of light (intensity) of the lights Lkc and Lg.

Further, when a foreign substance exists as the internal defect Kd in the glass substrate 10, ArF excimer laser light is introduced from the laser irradiation device 21 to the glass substrate 10, so that the above-described foreign matter is as shown in FIG. 6(B). The partial light amount Lkd of a specific threshold (1000 counts) or more is emitted within a specific range (for example, 20 to 50 mm), and the light Lg is emitted from a region other than the foreign matter of the synthetic quartz glass substrate 4. The computer 27 performs image processing on the light Lkd and Lg received by the CCD camera 23 and analyzes it, and determines the internal defect Kd as a foreign substance based on the shape of the partial light amount Lkd above the specific threshold value, and It is considered that the heterogeneous substance exists at a position generated by the light Lkd of the local light amount above the specific threshold value, and the heterogeneous substance is detected together with the position thereof. Here, in the case of FIG. 6(B), the horizontal axis represents the position of the glass substrate 10 in the X direction, and the vertical axis represents the amount of light (intensity) detected.

(3) Grinding step of the glass substrate for the mask base

The glass substrate 10 in which the internal defects Kc and Kd are not detected by the defect inspection device 20 of the glass substrate is mirror-polished or precision-polished to have a desired surface roughness, and is implemented. The cleaning process is performed to obtain a glass substrate 10 for a reticle base. At this time, the surface roughness of the main surfaces 11 and 12 is preferably such that the root mean square roughness (Rms (root-mean-square)) is 0.2 nm or less.

(4) Method of manufacturing photomask substrate

Next, a mask pattern is formed on the main surface 11 of the glass substrate 10 for a mask base obtained as described above by using a well-known sputtering apparatus, for example, a DC (direct current) magnetron sputtering apparatus. A film (halftone film) to obtain a halftone phase shift mask substrate as a mask base.

In addition, as a material used for the halftone film, a transition metal halide such as molybdenum, niobium, tungsten or zirconium and a transition metal halide of ruthenium are oxidized, nitrided, and oxynitrided as a main component. material. Further, the halftone film may be a layer of a transmittance adjusting layer that mainly adjusts the transmittance of the light to be exposed, and a layer of two or more layers of the phase adjustment layer that mainly adjusts the phase difference with respect to the light in the permeable film. structure.

(5) Manufacturing procedure of exposure mask (manufacturing method)

Next, a pattern is formed on the halftone film of the above-described mask substrate (halftone type phase shift mask substrate) by a well-known pattern forming method, thereby obtaining a halftone phase shift mask as an exposure mask. That is, a photoresist is applied to the surface of the halftone film, followed by heat treatment to form a photoresist film, and a specific pattern is written and developed on the photoresist film to form a photoresist pattern, and the light is formed. The resist pattern is used as a mask, and the halftone film is dry-etched to form a halftone film pattern, and then the photoresist pattern is removed to obtain an exposure mask on which the halftone film pattern is formed on the glass substrate 10.

According to the first embodiment, in the defect inspection step, the inspection light L is introduced in the direction from the end surface 13 toward the main surface 11 side, and is inclined with respect to the main surface 11 by only the inclination angle θg, and the presence or absence of the fluorescence is checked. Then, the inspection light L is introduced in the direction from the end surface 14 toward the main surface 12, and is inclined with respect to the main surface 12 by the inclination angle θg to check the presence or absence of the fluorescence, and further the inspection light L from the end surface with respect to the main surface 11 And 12 are introduced without being inclined to check the presence or absence of the fluorescent light, so that even when the chamfered surface is present, the inspection light can be surely reached to the vicinity of the surface inside the glass substrate, and the defect detection can be performed. Conduct an effective inspection.

In the case of the size of the glass substrate 10 to be inspected in the first embodiment, it is necessary to introduce the inspection light three times. However, depending on the size of the glass substrate, only the inspection light L is inclined from the end surface 13 toward the main surface 11 side. When the inspection light L is introduced by tilting the inspection light L from the end surface 14 toward the main surface 12 side so that the inspection light is spread over the entire specific region, the third inspection light L which is not inclined with respect to the main surfaces 11 and 12 is not necessarily required. Import. As a condition for introducing the inspection light twice, the following two conditions are satisfied: when the inspection light is introduced from the end surface 13 toward the main surface 11 side, the light ray L2 passes through the corner where the end surface 14 intersects the chamfer surface 14a. When the inspection light is introduced from the end surface 14 toward the main surface 12 side and the inspection light is introduced from the end surface 14 toward the main surface 12 side, the light beam L3 passes through the corner portion where the end surface 13 intersects the chamfer surface 13b, or is closer to the end surface 13 side.

Further, in the above-described first embodiment, an example in which the CCD camera 23 that receives the light Lkc, Lkd, and Lg emitted from the internal defects Kc and Kd is disposed on the side of the main surface 11 is disclosed in the defect inspection step. It may be disposed on the side of the end face other than the end faces 13 and 14 of the ArF excimer laser light. Further, as long as it is polished to such an extent that inspection light can be introduced, ArF excimer laser light can be introduced from the end surface 15 and the end surface 16.

Further, in the first embodiment, the case where the exposure light source is an ArF excimer laser has been described. However, if the wavelength is 200 nm or less, preferably light having a wavelength of 100 nm to 200 nm, the F2 excimer can also be used. Shoot. Alternatively, it is also possible to use a light source such as a D2 lamp to obtain light at the same wavelength as an ArF excimer laser or an F2 excimer laser, thereby splitting the center wavelength with an ArF excimer laser and an F2 excimer laser. The same light.

Further, in the above-described first embodiment, a color camera can be used as the CCD camera 23, and the internal defect of the glass substrate 10 and the wavelength of the wavelength other than the internal defect can be longer than the wavelength of the exposure wavelength of 200 nm or more. The light is taken, and the computer 27 classifies the image of the CCD camera 23 according to the colors of red, green, and blue, and distributes the intensity (light amount) of the light after image processing according to the color classification. And detect internal defects16. In this case, the computer 27 can also detect internal defects based on information such as the color, wavelength, and the like of the light processed by the color classification. Further, the detection of the internal defects can be performed at the final stage of the manufacturing process of the glass substrate for the reticle base.

Further, in the above-described first embodiment, the CCD camera 23 has been described as receiving light of a wavelength longer than the internal wavelength of the glass substrate 10 and the light of the exposure wavelength, which is longer than the exposure light. The spectroscope receives the light and measures the spectral characteristics (wavelength and intensity) of the internal defects and the intensity (light amount) distribution of the light Lkc, Lkd, and Lg to detect internal defects.

Further, in the first embodiment, the case of the halftone type phase shift mask substrate in which the halftone film is formed on the glass substrate for the mask base has been described, but the invention is not limited thereto. For example, a halftone type phase shift mask substrate including a halftone film on the glass substrate 10 and a light shielding film on the halftone film, or a light shielding film formed on the glass substrate 7 for the mask base may be used. A binary reticle substrate. The structure of the light-shielding film in this case includes a two-layer laminated structure in which a light-shielding layer and a surface anti-reflection layer are laminated from the substrate side, or a three-layer laminated structure in which a back surface anti-reflection layer is further interposed between the substrate and the light-shielding layer. Wait. As a material used for the light-shielding film, firstly, a material containing chromium as a main component is used, and in order to satisfy the characteristics necessary for the back surface antireflection layer, the light shielding layer, and the surface antireflection layer, chromium may be used as a main component and moderately A material that is oxidized, nitrided, carbonized, and the like. Further, examples of the material which can be applied to the light-shielding film other than chromium include a transition metal containing a transition metal such as molybdenum, tungsten or zirconium, and a transition metal halide. In the same manner as in the case of chromium, the transition metal halide can be used. The main component is moderately oxidized, nitrided, carbonized, and the like. In addition, it is also possible to form a light-shielding film having a two-layer laminated structure or a three-layer laminated structure by using a material mainly composed of ruthenium, oxidized, nitrided, carbonized or the like as a main component. Furthermore, a photoresist film may be formed on the halftone phase shift mask base and the light shielding film of the mask base.

(Embodiment 2)

In the first embodiment, it is necessary to introduce the inspection light three times into the glass substrate 10 in accordance with the size of the glass substrate 10 to be inspected, that is, to introduce the inspection light L from the end surface 13 toward the main surface 11 side, and to introduce the inspection light L. The end surface 14 is inclined and introduced toward the main surface 12 side, and the inspection light L is introduced from any one end surface without tilting with respect to the main surfaces 11 and 12. On the other hand, in the second embodiment, the substantially parallel inspection light of the inspection light source is converted into divergent light by the concave lens, and is introduced into the glass substrate 10, thereby preventing the size of the glass substrate 10 to be inspected. The inspection light L is introduced from any one of the end faces without tilting with respect to the main surfaces 11, 12, and the inspection light can be spread over the entire specific region by the introduction of the inspection light twice.

As shown in Fig. 7, in the second embodiment, the concave lens 28 is provided in front of the end surface 13 (end surface 14), so that the inspection light L becomes divergent light having a divergence angle of θc and is inclined with respect to the main surface 11 (main surface 12) only The angle θg is inclined and introduced into the glass substrate 10. In this case, the inclination angle θg is an angle of the light ray L9 (light ray L12) which passes through the center of the concave lens 28 and whose ray angle is not changed with respect to the main surface 11 (main surface 12). Further, the divergence angle θc refers to light rays L7 and L8 that are introduced into the glass substrate 10 through the respective corner portions where the end surface 13 (end surface 14) and the chamfered surfaces 13a and 13b (the chamfered surfaces 14a and 14b) intersect ( Before the light beams L10 and L11 are introduced into the glass substrate 10, the inspection light L which is substantially parallel light is diverged light by the concave lens 28, and intersects the extension lines of the light beams L7 and L8 (light rays L10 and L11). The angle θc formed by the extension lines of the points. When the light rays L7 and L8 (light rays L10, L11) of the inspection light are introduced into the glass substrate 10 from the end surface 13 (end surface 14), the angle of the light changes due to the difference in refractive index between the air and the glass substrate 10, so the glass substrate The angle formed by the extension lines of the light L7 and L8 (light rays L10, L11) in 10 is not the same as θc.

The inclination angle θg and the divergence angle θc are set so as to satisfy all of the following conditions. That is, with respect to the inspection light L introduced into the glass substrate 10 from the end surface 13, the light ray L5 must pass through the intersection line Be of the boundary surface E and the boundary surface B or be closer to the end surface 13 side, and the light ray L6 must pass through the end surface 14 and The corner portion where the chamfered surface 14a intersects or the end surface 14 side thereof. Further, regarding the inspection light L introduced into the glass substrate 10 from the end surface 14, the light ray L9 must pass through the intersection line Df of the boundary surface F and the boundary surface D, or be closer to the end surface 14 side, and the light ray L8 must pass through the end surface 13 The corner portion intersecting the chamfered surface 13b or the end surface 13 side thereof.

For example, when the production of the glass substrate for the reticle base is completed (after the completion of the polishing step), the aspect ratio is about 152 mm × 152 mm × 6.35 mm, and the amount of chamfering m is 0.6 mm, the inspection light should be minimized. When the specific region to be reached is 132 mm × 132 mm × 6.4 mm, the sum of the half angle of the divergence angle θc and the inclination angle θg may be 2.4° or more, and the divergence angle θc may be 0.8° and the inclination angle may be 2.0°.

The inspection light L having the divergence angle θc satisfying the above conditions is inclined at the inclination angle θg toward the main surface 11 side, and is introduced from the end surface 13 to check the presence or absence of the fluorescence, and further the inspection light L having the same divergence angle θc The main surface 12 is inclined at an inclination angle θg and is introduced from the end surface 14 to check the presence or absence of fluorescence, whereby the inspection light can be made as a whole of 132 mm × 132 mm × 6.4 mm as a specific region, so that the entire specific region can be performed. Inspection of internal defects.

Further, since the concave lens 28 is necessary for causing the substantially parallel inspection light from the inspection light source to become divergent light, even a spherical concave lens satisfies the above-described function. However, it is necessary to check the divergence of the light toward the thickness direction of the substrate, and the divergence of the direction of the inspection light in the direction parallel to the main surface is not necessarily required. On the other hand, in consideration of the decrease in the intensity of the light of the inspection light due to the divergence, it is preferable to minimize the divergence toward the direction parallel to the main surface. In consideration of such aspects, it is preferable to use a cylindrical lens as the concave lens 28, and mainly to illuminate the inspection light only in the thickness direction of the substrate. Further, any mechanism may be used as long as the substantially parallel inspection light can be converted into divergent light, and a concave mirror can also be used. In the case of the concave mirror, it is preferable to use a cylindrical concave mirror mainly to cause the inspection light to diverge only in the thickness direction of the substrate. Further, the method of manufacturing the glass substrate for the mask base, the method of manufacturing the mask base, and the method of manufacturing the exposure mask are the same as those in the first embodiment.

(Embodiment 3)

The third embodiment differs from the first embodiment in that (3) before the polishing step of the glass substrate for the mask base, but after (4) the manufacturing step of the mask substrate, the internal defects of the glass substrate are inspected. The step is the defect inspection step.

The inside of the glass substrate was inspected by the photomask substrate manufactured by the (4) photomask substrate manufacturing step by the same method as (2) the internal defect inspection step of the photomask base glass substrate. The size of the glass substrate of the mask base is manufactured with the object of the aspect ratio of about 152 mm × 152 mm × 6.35 mm and the amount of chamfering m of 0.6 mm. If an error is added, the specific area where the inspection light is to be reached should be set to a minimum. 132 mm × 132 mm × 6.4 mm, the inclination angle θg of the inspection light may be 2.4°.

According to the third embodiment, the same effects as those in the first embodiment can be obtained. Further, since the fluorescent light is reflected at the interface between the main surface 11 of the substrate and the film, the effect of more easily identifying the presence or absence of the fluorescent light can be obtained. Further, as a method of introducing the inspection light into the glass substrate 10 of the reticle base, as shown in the second embodiment, the inspection light L can be converted into divergent light having a divergence angle θc using the concave lens 28 or the like, from the end surface 13 The side and the end surface 14 side are respectively introduced into the inside of the glass substrate 10. The divergence angle θc and the inclination angle θg at this time may be the same as those in the second embodiment.

It is also possible to perform the same internal defect inspection as that performed on the mask substrate by the exposure mask manufactured by the (5) manufacturing step of the exposure mask. Further, the amount of fluorescent light generated by the internal defect caused by the irradiation of the inspection light is greatly changed depending on the irradiation intensity of the inspection light and the type or structure of the internal defect, so that it is necessary to be more sure. If the internal defects are excluded, the stage of the unpolished glass substrate, the stage of polishing the glass substrate for the reticle base, the stage of the reticle base, and the stage of the exposure reticle may be any number of stages, or all The stage performs an internal defect check.

(Embodiment 4)

FIG. 8 is an explanatory view showing an internal defect inspection step of the glass substrate for a reticle base according to Embodiment 4 of the present invention, FIG. 9 is an enlarged view of a portion A of FIG. 8, and FIG. 10 is an explanatory diagram of a divergence angle θc, and FIG. The structure of the apparatus for performing the internal defect inspection step of the glass substrate for a reticle base according to the first embodiment of the present invention. Hereinafter, a method of manufacturing a glass substrate for a mask base according to Embodiment 4 of the present invention, a method for producing a mask base, and a method for producing an exposure mask will be described with reference to the drawings. In addition, the glass substrate for the mask base to be inspected in the fourth embodiment is the same as the glass substrate for the mask base shown in FIGS. 1 and 2, and therefore, the same portions will be denoted by the same reference numerals.

The method for producing a glass substrate for a mask base according to the fourth embodiment includes the steps of: (1) a grinding step of a glass substrate for a mask base to be subjected to defect inspection; and (2) a defect inspection step of a glass substrate for a mask base; (3) A polishing step of a glass substrate for a mask base. Further, in the method of manufacturing a mask base according to the fourth embodiment, the step of manufacturing the mask base is performed on the glass substrate for a mask base manufactured by the steps (1) to (3). Further, in the method for producing an exposure mask according to the fourth embodiment, the manufacturing step of the exposure mask is performed on the mask substrate manufactured by the step (4). In the above-described steps, the most important feature of the fourth embodiment is the method for inspecting the internal defects of the glass substrate for the mask base used in the defect inspection step of the glass substrate for the mask base, and the other steps are generally performed using well-known steps. Therefore, the following description of the well-known steps will be given as a minimum, and the defect inspection method of the glass substrate for a reticle base will be mainly described.

Further, (2) the defect inspection step of the glass substrate for the mask base, even for the (3) glass substrate after the polishing step of the glass substrate for the mask base, and (4) the mask substrate after the manufacturing step of the mask substrate, Or (5) the exposure mask after the manufacturing step of the exposure mask is used, and the accuracy of the internal defect inspection is not substantially different. However, if this step is performed by first performing the polishing step of the glass substrate for the mask base (3), (4) the manufacturing step of the mask substrate, and (5) the manufacturing steps of the exposure mask, It is preferable to carry out this step before the grinding step of (3), since all the glass substrates including the defective products having internal defects are subjected to polishing and film formation, which causes a large waste. Further, when focusing on the case where the internal defect is more reliably found, the glass substrate for the reticle substrate on which the polishing step of the glass substrate is completed, the reticle substrate on which the film for pattern formation is formed on the glass substrate, and the exposure Use the mask to perform the defect inspection step.

(1) Grinding step of a glass substrate for a mask base which is an object of internal defect inspection

A synthetic quartz glass ingot prepared by a well-known method (for example, refer to Japanese Patent Laid-Open No. Hei 8-31723, No. 2003-81654, etc.), cut out about 152.4 mm × about 152.4 mm × about A plate-shaped body of 6.85 mm to obtain a glass substrate of synthetic quartz. The glass substrate includes two major surfaces opposite to each other and four end faces orthogonal to the two major surfaces.

After chamfering the corner portion where the main surface and the end surface of the glass substrate intersect, the end surface into which the inspection light is introduced is mirror-polished so that the inspection light can be introduced into the inside of the glass substrate to obtain the glass substrate 10 for the mask base. The glass substrate 10 is the same as the glass substrate for a mask base shown in FIGS. 1 and 2, and includes two main surfaces 11, 12, four end faces 13, 14, 15, 16 and eight chamfered faces. 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b. Here, the surface roughness Ra (arithmetic mean roughness) of the end surface (one end surface) 13 into which the inspection light is introduced is set to be about 0.03 μm or less. Further, since all of the four end faces are mirror-polished by the polishing step of the mask base, the other end faces 14, 15, 16 can also be mirror-polished at the stage of the grinding step. The reticle substrate thus obtained is supplied to the glass substrate 10 to the next step, that is, the inspection step of the internal defect.

(2) Defect inspection procedure for the glass substrate for the mask base

This step is a step of inspecting the presence or absence of internal defects of the reticle base glass substrate 10 obtained as described above by the defect inspection method described below. Hereinafter, a method of inspecting the glass substrate for a reticle base used in this step will be described.

In FIG. 8, the inspection light L having substantially parallel light having a divergence angle of 2 mrad is converted into divergent light by the concave lens 28, and is introduced into the glass substrate 10 from the end surface 13 of the glass substrate 10 (shown by a solid line in FIG. 8) At this time, the presence or absence of the fluorescent light generated by the internal defect by the inspection light is examined.

In this case, the divergence angle of the inspection light is set such that the inspection light L introduced into the glass substrate 10 is introduced into the glass substrate through the corner portion where the end surface 13 intersects the chamfered surfaces 13a and 13b. When the light is L1 and L2, the light beams L1 and L2 are located on the boundary surfaces E and F (see FIGS. 9 and 10) on the surface and the back surface of the main surface 11 and 12 on the specific region, and the end surface 13 side of the specific region. The intersection lines Be, Bf of the boundary surface B are on the side of the end face 13 or more.

Here, the divergence angle refers to substantially parallel light before the light rays L1 and L2 introduced into the glass substrate 10 are introduced into the glass substrate 10 through the corner portions where the end surface 13 and the chamfered surfaces 13a and 13b intersect. In the state where the inspection light L becomes divergent light by the concave lens 28, as shown in FIG. 10, the angle (θc) formed by the extension lines at the point where the extension lines of the light rays L1, L2 intersect each other (when the inspection light is When the light beams L1 and L2 are introduced into the glass substrate 10 from the end surface 13, the angle of the light changes due to the difference in refractive index between the air and the glass substrate 10, so that the extension lines of the light rays L1 and L2 in the glass substrate 10 are formed. The angle is not the same as θc).

Here, the range of the thickness direction of the reticle base of the specific region (the direction between the main surface 11 and the main surface 12) is not necessarily required to cause the inspection light to reach the entire region in the thickness direction. The reason for this is that when the defect inspection step is performed after the grinding step is finished, in the subsequent grinding step, a certain amount of glass is cut in the thickness direction from both sides by grinding the main surfaces 11 and 12 (Fig. 9). Part 11a), so even if there is an internal defect in the area to be cut, the internal defect has been removed in the glass substrate for the reticle base after completion. However, in consideration of the fact that the main surface on the side where the film for pattern formation is formed and the main surface on the opposite side thereof are slightly different in amount, the two main surfaces are not completely flat, etc., it is preferable to inspect the light in the thickness direction. The area you arrived in was slightly marginal.

For example, in the case of a glass substrate for a reticle base having a size of about 152 mm × 152 mm on the main surface (including the size of the chamfered portion), the thickness (thickness in the thickness direction) is 6.85 mm after the end of the grinding step. Grinding is carried out to a target of 6.35 mm. In consideration of the above-described margin, it is sufficient that the inspection light reaches a region having a thickness of at least 6.4 mm based on the center of the substrate in the thickness direction. In other words, in the glass substrate after the completion of the grinding step, the portion outside the center of the substrate in the thickness direction is more than 6.4 mm, and is removed in the subsequent polishing step. Therefore, even if the portion is excluded from the inspection. There is no problem outside the area.

On the other hand, the range of the main surface side of the specific region is a region where the transfer pattern is formed on the film when the photomask substrate is fabricated using the glass substrate for the reticle base and the exposure reticle is formed based on the reticle substrate. As long as the minimum coverage is enough. This is because the exposure mask is formed on the glass substrate for the reticle base, and is placed on the reticle stage of the exposure apparatus, and the pattern is transferred to the transfer target (wafer or the like) to form a turn. The exposed light of the areas on the outer surfaces 11 and 12 on the outer side of the printed pattern area is shielded by the film, so that even if there is an internal defect in the area, the transfer target is not adversely affected.

For example, in the case where the main surface has a glass substrate for a mask base having a size of about 152 mm × 152 mm, the region where the transfer pattern is formed is usually an area of 132 mm × 132 mm on the basis of the center of the mask base. In this case, the boundary surface B of the specific region may be set at least at a distance of 66 mm from the center of the mask base toward the end surface 13 in parallel with the end surface 13. The light rays L1 and L2 in the glass are selected to be divergent in such a manner that the boundary surface B is on the two intersecting lines Be and Bf where the boundary surfaces E and F on the two main surfaces 11 and 12 are intersected, or on the side closer to the end surface 13 side. The angle θc is sufficient. Further, the exposure mask is provided on the mask stage of the exposure apparatus in such a manner that the main surface on the side where the film is not formed faces the light source side of the exposed light. Therefore, even if light exposed in an area outside the specific area can be irradiated to the inside of the glass substrate 10, if there is an internal defect, fluorescence is generated therefrom. When the internal defect is located in the vicinity of the boundary face B of the specific region, the fluorescent light emitted from the place may adversely affect the pattern transfer toward the transfer object. In consideration of such a case, it is preferable to set the specific region with a margin to a region inside the 142 mm × 142 mm with respect to the center of the mask base. If it is further made to have a margin, it is more preferable to set the specific area to an area inside, for example, 146 mm × 146 mm.

In consideration of the above, when a glass substrate for a reticle base of about 152 mm × 152 mm × 6.35 mm is manufactured, the specific area to be inspected in the internal defect inspection step is at least 132 mm × 132 mm × 6.4 based on the center of the substrate. The inside of the glass substrate of mm can be used. Further, when a more accurate internal defect inspection is required, it is preferable to set the specific region to the inside of the glass substrate with the substrate center as a reference of 142 mm × 142 mm × 6.45 mm.

By selecting the divergence angle θc in this manner, only the inspection light L is introduced into the glass substrate 10 from the end surface 13 of the glass substrate 10, and the inspection light can be irradiated onto the entire specific region of the glass substrate 10 where the internal defect inspection should be performed. Thereby, even minute internal defects of the glass substrate 10, particularly near the surface and the back surface, can be detected without fail.

That is, as shown in FIG. 8, the inspection light L introduced into the glass substrate 10 from the end surface 13 of the glass substrate 10 is also included in the glass substrate 10 in addition to the regions S3 and S4 which are outside the light beams L1 and L2. All areas. Thereby, the inspection light L can be spread over the region where the transfer pattern is formed in the glass substrate 10, and by detecting the defective light generated at this time, the defect detection can be performed relatively easily.

In the fourth embodiment, the divergence angle θc is specifically as follows.

‧Check light: ArF excimer laser light (exposure wavelength: 193 nm)

‧Material of glass substrate 10: Synthetic quartz glass

‧Refractive index: 1.52 (exposure wavelength: at 193 nm)

‧ size of glass substrate 10

Vertical and horizontal: 152 × 152mm,

Thickness tg: 6.4 mm (target thickness after grinding step is 6.35 mm + error range)

Chamfer amount m (refer to Figure 9): 0.6mm

‧Specific area: 132mm × 132mm × 6.4mm (based on the center of the substrate)

‧Check the divergence angle of light θg: 4.8°

‧ concave lens 28: cylindrical lens (focal length: 300mm)

‧Distance between concave lens 28 and end face 13: 10 mm

The divergence angle θc in the above-described fourth embodiment is an angle at which the boundary surface B of the specific region on the end face 13 side can be covered. The divergence angle θc may be greater than the minimum angle only if it is considered to satisfy the action and effect of the invention of the present invention. However, as the divergence angle θc is increased, the light intensity (density) of the inspection light introduced into the glass substrate is gradually reduced. Therefore, if the light intensity of the inspection light source is the same, it is possible to illuminate the inspection light from the internal defect. The intensity of the emitted fluorescent light is also gradually reduced, making it difficult to detect fluorescence. Regarding this problem, if the light intensity of the inspection light source is enhanced, it is basically solved. However, if the light intensity of the inspection light source is excessively increased, there is a possibility that damage to the inside of the substrate is caused by the increase in the energy of the inspection light. In consideration of the economic aspect related to the aspect and the device enhancement, the divergence angle θc is preferably a minimum angle of the boundary surface B of the specific region covering the end surface 13 side (the end surface on which the inspection light is introduced).

For example, when the production of the glass substrate for the reticle base is completed as described above (after the end of the polishing step), the aspect ratio is about 152 mm × 152 mm × 6.35 mm, and the amount of chamfering m is 0.6 mm. When the specific area where the inspection light arrives is 132 mm × 132 mm × 6.4 mm, the divergence angle θc may be 4.8° or more. Further, when the substrate size is the same and the specific region where the inspection light is to be reached is 142 mm × 142 mm × 6.45 mm, the divergence angle θc may be 10.3° or more. Further, the divergence angle is considered in consideration of the risk of damage to the substrate due to a decrease in the light intensity of the inspection light due to the divergence angle diverging by the concave lens, and the increase in the light intensity of the inspection light source. Θc is preferably 7.0 or less.

Further, the concave lens 28 is necessary for causing the substantially parallel inspection light from the inspection light source to become divergent light, and therefore the concave lens of the spherical surface satisfies this function. However, it is necessary to check the divergence of the light toward the thickness direction of the substrate, and the divergence of the direction of the inspection light in the direction parallel to the main surface is not necessarily required. On the other hand, in consideration of the decrease in the intensity of the light of the inspection light due to the divergence, it is preferable to minimize the divergence toward the direction parallel to the main surface. In consideration of such aspects, it is preferable to use a cylindrical lens as the concave lens 28, and mainly to illuminate the inspection light only in the thickness direction of the substrate. Further, any mechanism may be used as long as the substantially parallel inspection light can be converted into divergent light, and a concave mirror can also be used. In the case of the concave mirror, it is preferable to use a cylindrical concave mirror mainly to cause the inspection light to diverge only in the thickness direction of the substrate.

Next, the apparatus configuration for carrying out the defect inspection step of the above-described fourth embodiment will be described with reference to Fig. 11, and the defect inspection step of the glass substrate for a mask base according to the fourth embodiment of the present invention will be described in more detail. In Fig. 11, reference numeral 20 is a defect inspection device for a glass substrate. The glass substrate defect inspection device 20 includes a laser device 21 for generating inspection light L and irradiated to a glass substrate, and an XYZ stage 22 on which the glass substrate 10 is placed and oriented in the X direction, the Y direction, and the Z direction. Moving separately and transmitting its position information; CCD camera 23, which detects defective light generated in the glass substrate 10; computer 27, which inputs image information from the CCD camera 23 and position information from the XYZ platform 22, and performs specific And a cylindrical lens 28 that introduces the inspection light L into divergent light and introduces it into the glass substrate 10.

The laser device 21 is disposed on the side of the end surface 13 of the glass substrate 10 placed on the XYZ stage 22. The cylindrical lens 28 is provided on the side of the end surface 13 of the glass substrate 10 along the end surface 13. The inspection light L emitted from the laser device 21 is converted into specific divergent light by the cylindrical lens 28, and then introduced into the glass substrate 10 through the end surface 13.

The inspection light beam shape emitted from the laser device 21 is 7.0 mm × 4.0 mm, the power is 6 mJ, and the pulsed ArF excimer laser light (wavelength: 193 nm) having a frequency of 400 Hz, the cylindrical lens 28 and the glass substrate The end faces 13 or 14 of 10 are arranged in parallel, and the end faces thereof are formed to be substantially the same as the longitudinal and lateral widths. Further, as a function of the lens, a cut surface (substrate thickness direction) which is a right angle in a longitudinal direction (a direction parallel to the main surface of the substrate) functions as a concave lens. As a function of the concave lens, as described in detail, the inspection light L is made to become a divergent light of a specific divergence angle. Furthermore, there is no lens action in the length direction.

The XYZ stage 22 is capable of placing the glass substrate 10 in the XYZ direction, moving the glass substrate to a desired position, and transmitting the position information to the computer 27. In the case of performing the defect inspection, the glass substrate 10 is placed at the position where the inspection is started, and then the inspection light L is introduced into the glass substrate 10 by the laser device 21, and the fluorescent light is captured by the CCD camera 23 The image of Lkc and Lkd is sent to the computer 27 and stored in the image information and the location information. Next, the XYZ stage 22 is driven to move the glass substrate 10 in the Y direction by a distance corresponding to the width of the inspection light L, and the inspection light L is irradiated in the same manner, and the image of the fluorescent light Lk and Lk at this time is captured by the CCD camera 23, And the location information is sent to the computer 27 together with the above image information. By repeating this operation, the inspection light L is introduced from all the ends of the end face 13 to the other end.

Next, the glass substrate 10 is moved on the XYZ stage 22, and the end surface 14 is disposed to face the cylindrical lens 28. Then, the inspection light L is introduced from the end surface 14. Next, the same operation as in the case of introduction from the end face 13 is repeated, and the inspection light L is introduced from all the ends of the end face 14 to the other end. Thereby, the inspection light L is irradiated to all areas in the glass substrate 10 to store images of defective light in all areas in the glass substrate 10. Further, in addition to providing the laser device 21 and the cylindrical lens 28 on the side of the end surface 13 of the glass substrate 10 as described above, if it is also provided on the side of the end surface 14 (shown by a broken line in FIG. 11), it can be maintained. The entire area is inspected by fixing the glass substrate 10 to the XYZ stage 22.

The CCD camera 23 is disposed on the side of the surface 11 which is one of the front surface and the back surface (above the figure) to produce an image based on the information of the light emitted from the glass substrate 10. That is, the fluorescent light Lkc, Lkd generated by the internal defects of the glass substrate 10 is detected, the image of the fluorescent light is captured, and the image information is transmitted to the computer 27. Further, in the fourth embodiment, a so-called black and white camera is used as the CCD camera 23.

The computer 27 inputs an image from the CCD camera 23, performs image processing at each position in the Y direction of the glass substrate 10, and sets the position of the glass substrate 10 in the Y direction according to the position in the X direction of the glass substrate 10. The amount of light (intensity) of the light Lkc, Lkd, and Lg received by the CCD camera 23 is analyzed. In other words, when the light amount of the light Lkc, Lkd, and Lg includes a partial light amount of a predetermined threshold or more, the computer 27 determines that the internal defects Kc and Kd have emitted the light Lkc and Lkd of the partial light amount of the specific threshold or more. Therefore, the types of internal defects Kc and Kd (local veins, contents, foreign matter) and the positions of the internal defects Kc, Kd are determined based on the shape of the partial light amount Lkc, Lkd emitted by the internal defects Kc, Kd, and the like. (The positions of the glass substrate 10 in the X direction and the Y direction) are collectively specified and detected.

For example, when local veins or contents are present as the internal defects Kc in the glass substrate 10, the local veins or contents are detected together with the position thereof by the method previously described using FIG. 6(A), and when When a foreign substance is present as the internal defect Kd in the glass substrate 10, the above-described foreign matter is detected together with the position thereof by the method previously described using FIG. 6(B).

The glass substrate 10 of the glass substrate on which the internal defects Kc and Kd are not detected by the defect inspection device 20 is an inspection product, and is supplied to the next polishing step.

(3) Grinding step of the glass substrate for the mask base

The glass substrate 10 which is a good product by the (2) defect inspection step, the main surfaces 11, 12, the end faces 13, 14, 15, 16 and the chamfered faces 13a, 13b, 14a, 14b, 15a, 15b 16a and 16b are subjected to mirror polishing and precision polishing to have a desired surface roughness, and then subjected to a cleaning treatment to obtain a glass substrate 10 for a mask base. The surface roughness of the main surfaces 11 and 12 at this time is preferably a root mean square roughness (Rms) of 0.2 nm or less.

(4) Manufacturing steps of the mask substrate (manufacturing method)

Next, a mask pattern is formed on the main surface 11 of the glass substrate 10 for a mask base obtained as described above by using a well-known sputtering apparatus, for example, a DC (direct current) magnetron sputtering apparatus. A film (halftone film) to obtain a halftone phase shift mask substrate as a mask base. In addition, as a material used for the halftone film, a transition metal hydride containing a transition metal such as molybdenum, niobium, tungsten or zirconium and lanthanum may be oxidized, nitrided or oxynitrided as a main component. Material. Further, the halftone film may be two or more layers including a transmittance adjustment layer that mainly adjusts the transmittance of the light for exposure, and a phase adjustment layer that adjusts the phase difference mainly for the light that is exposed to the permeable film. The layered structure.

(5) Manufacturing procedure of exposure mask (manufacturing method)

Next, a pattern is formed on the halftone film of the above-described mask substrate (halftone type phase shift mask substrate) by a well-known pattern forming method, thereby obtaining a halftone phase shift mask as an exposure mask. That is, a photoresist is applied to the surface of the halftone film, followed by heat treatment to form a photoresist film, and a specific pattern is written and developed on the photoresist film to form a photoresist pattern, and the photoresist is formed. The pattern is used as a mask, and the halftone film is dry-etched to form a halftone film pattern, and then the photoresist pattern is removed, thereby obtaining an exposure mask on which the halftone film pattern is formed on the glass substrate 10.

According to the fourth embodiment, in the defect inspection step, the inspection light L having the divergence angle θc is introduced from the end surface 13 of the glass substrate 10 to detect the defective light, and the inspection light L is introduced from the end surface 14 facing the end surface 13 Similarly, the defective light is detected, so that even in the case where the chamfered surface is present, the inspection light can be surely reached to the vicinity of the surface inside the glass substrate, and at the same time, the inspection light is suppressed by suppressing the divergence angle to be small. The attenuation is suppressed to a small extent, and the defect detection can be performed, so that an effective inspection can be performed.

Further, in the above-described fourth embodiment, an example in which the CCD camera 23 that receives the light Lkc, Lkd, and Lg emitted from the internal defects Kc and Kd is disposed on the side of the main surface 11 is disclosed in the defect inspection step. The CCD camera 23 may be disposed on the main surface 12 side or the end surfaces 14, 15, 16 side. Moreover, as long as it is polished to the end surface to which the inspection light can be introduced, ArF excimer laser light may be introduced into the end surface side other than the end surface 13.

Further, in the above-described fourth embodiment, the case where the exposure light source is an ArF excimer laser has been described. However, if the wavelength is 200 nm or less, preferably light having a wavelength of 100 nm to 200 nm, the F2 excimer can also be used. Shoot. Further, it is also possible to use a light source such as a D2 lamp to obtain a wavelength similar to that of an ArF excimer laser or an F2 excimer laser, and to split the light so that the center wavelength is the same as that of the ArF excimer laser or the F2 excimer laser. Light.

Further, in the above-described fourth embodiment, an example in which a monochrome camera is used as the CCD camera 23 has been disclosed, but a color camera may be used as a CCD camera to receive internal defects of the glass substrate 10 and regions other than the internal defects. The light having a wavelength longer than the exposure wavelength of 200 nm or longer is photographed, and the computer 27 sorts the images of the CCD camera 23 according to the colors of red, green, and blue, and sorts according to the color according to the color. The intensity (light amount) of the light after the image processing is performed to detect the internal defect 16. In this case, the computer 27 can also detect internal defects based on information such as the color or wavelength of the light after image processing by color classification. Further, the detection of the internal defects can be performed at the final stage of the manufacturing process of the glass substrate for the reticle base.

Further, in the above-described first embodiment, the CCD camera 23 has been described as receiving light having a longer wavelength than that of an internal defect of the glass substrate 10 and a region other than the internal defect, but may be split. The device receives the light to measure the spectral characteristics (wavelength and intensity) of the internal defects and the intensity (light amount) distribution of the light 15 and 17 to detect internal defects. Moreover, the detection of fluorescence can also be performed by visual inspection by an inspector.

Further, in the first embodiment, the case of the halftone type phase shift mask substrate in which the halftone film is formed on the glass substrate for the mask base has been described, but the invention is not limited thereto. For example, a halftone type phase shift mask substrate including a halftone film on the glass substrate 10 and including a light shielding film on the halftone film, or a light shielding film formed on the glass substrate 1 for the mask base may be used. A binary reticle substrate. The structure of the light-shielding film in this case includes a two-layer laminated structure in which a light-shielding layer or a surface anti-reflection layer is laminated from the substrate side, or a three-layer laminated structure in which a back surface anti-reflection layer is further added between the substrate and the light-shielding layer. Wait. As a material used for the light-shielding film, firstly, a material containing chromium as a main component is used, and in order to satisfy the characteristics necessary for the back surface antireflection layer, the light shielding layer, and the surface antireflection layer, chromium may be used as a main component and moderately A material that is oxidized, nitrided, carbonized, and the like. Further, examples of the material which can be applied to the light-shielding film other than chromium include a transition metal containing a transition metal such as molybdenum, tungsten or zirconium, and a transition metal halide. In the same manner as in the case of chromium, the transition metal halide can be used. The main component is moderately oxidized, nitrided, carbonized, and the like. In addition, it is also possible to form a light-shielding film having a two-layer laminated structure or a three-layer laminated structure by using a material mainly composed of ruthenium, oxidized, nitrided, carbonized or the like as a main component. Furthermore, a photoresist film may be formed on the halftone phase shift mask base and the light shielding film of the mask base.

(Embodiment 5)

In the fifth embodiment, the presence or absence of fluorescence in a specific region is inspected only by introducing the inspection light from the end surface 13, but by using a concave lens, the substantially parallel inspection light of the inspection light source is converted into divergent light, and the light intensity per unit area is obtained. Will be reduced a lot. In order to check the presence or absence of the fluorescence of the entire specific region by using the inspection light (diverging light) introduced from one of the end faces 13, the inspection light needs at least the boundary surface D of a specific region on the side of the end face 14 opposite to the end face 13. (See Fig. 12) The size of the light intensity at which the presence or absence of fluorescence is sufficiently detected.

As described above, by enhancing the light intensity of the inspection light source itself, the light intensity of the divergent light on the boundary surface D of the specific region on the end face 14 side can be improved. However, at this time, the light intensity of the divergent light inside the substrate on the side of the end face 13 on the light introduction side is inevitably increased. Therefore, depending on the intensity of the light intensity of the enhanced inspection light source, it is possible to cause the inside of the substrate on the end face 13 side. damage.

In the fifth embodiment, the above problem is solved by introducing divergent light of the inspection light from the end face 13 side and from the end face 14 side. In the fifth embodiment, as shown in FIG. 12, by dividing the distance between the end surface 13 and the end surface 14 into two intermediate portions C1, C2 on the main surfaces 11, 12, and the end surface 13 and the end surface 14 parallel intermediate faces C, and it will be necessary to divide the specific area in which the inspection light arrives into two. Then, by the inspection light introduced from the end surface 13 side, the boundary surface B on the end surface 13 side of the specific region, the intermediate surface C, and the boundary surfaces E and F on the side of the main surfaces 11 and 12 are inspected at least. The presence or absence of the fluorescent light in the area, and the inspection surface light introduced from the end surface 14 side, and the boundary surface D on the end surface 14 side of the specific region, the intermediate surface C, and the sides of the two main surfaces 11, 12 are inspected to the minimum. The presence or absence of fluorescence in the area surrounded by interfaces E and F. Thereby, the introduced divergent light can ensure the light intensity of the presence or absence of the fluorescent light at least at the intermediate surface C, and the damage inside the substrate on the end surface side to which the divergent light is introduced can be suppressed. In this case, the divergence angle θc of the inspection light can be set as follows: if the divergent light introduced into the glass substrate 10, that is, the outermost light in the inspection light L is L1 and L2, the light L1, L2 It falls on the intersection lines Be, Bf, De, Df of the boundary surfaces E and F on the surface of the specific area and the two main surfaces 11 and 12 on the back surface.

In the fifth embodiment, after the internal defect inspection of the inspection light is introduced from the end surface 13 side, the method of introducing the inspection light from the end surface 14 side as the next step is performed, and the substrate 10 can be changed to be placed on the XYZ stage 22 as long as it can be changed. The direction is such that the positions of the end face 13 and the end face 14 are exchanged. Further, as shown by the broken line in FIG. 11, the laser irradiation device 21 and the cylindrical lens 28 may be disposed on the end surface 14 side. Further, in the case of the second embodiment, it is necessary to mirror-finish the two end faces 13 and 14 to which the inspection light is introduced. Other matters relating to the method for producing a glass substrate for a mask base, the method for producing a mask substrate, and the method for producing an exposure mask are the same as those in the fourth embodiment.

(Embodiment 6)

In the same manner as in the fifth embodiment, the sixth embodiment introduces the divergence light of the inspection light from the end surface 13 side and the end surface 14 side, thereby solving the problem of damage caused by introducing the inspection light into the glass substrate. However, the sixth embodiment is different from the fifth embodiment in that the light intensity of the inspection light source can be made substantially equal to the case of the previous internal defect inspection step using parallel light.

In the sixth embodiment, as shown in FIG. 13, the inspection surface light introduced from the end surface 13 side is used to inspect the boundary surface D on the intermediate surface C and the end surface 14 side, and the main surfaces 11 and 12 side at the minimum. The presence or absence of fluorescence of the area surrounded by the boundary surfaces E and F. Further, by the inspection light introduced from the end surface 14 side, the boundary surface B on the intermediate surface C and the end surface 13 side, and the area surrounded by the boundary surfaces E and F on the side of the main surfaces 11 and 12 are inspected at a minimum. The presence or absence of light. In this case, the divergence angle θc of the inspection light can be set as follows: when the light emitted to the outside of the inspection light L, which is the divergent light introduced into the glass substrate 10, is L3 or L4, the light L3, L4 falls on the intersection lines Ce, Cf, De, Df of the boundary surfaces E, F and the intermediate surface C on the surface of the specific region and the two main surfaces 11 and 12 on the back surface. As a result, the divergence angle θc can be made relatively small as compared with the case of the fourth and fifth embodiments, and the decrease in the light intensity of the inspection light due to the divergence can be minimized. Thereby, the light intensity of the inspection light source can be set to be substantially equal to the case of the previous internal defect inspection step using the parallel light, so that the damage caused by introducing the inspection light into the glass substrate can be suppressed to the previous The degree of technology is equal.

For example, when the production of the glass substrate for the reticle base is completed (after the completion of the polishing step), the aspect ratio is about 152 mm × 152 mm × 6.35 mm, and the amount of chamfering k is 0.6 mm, the inspection light should be minimized. When the specific region to be reached is 132 mm × 132 mm × 6.4 mm, the divergence angle θc may be 0.7 or more.

In the case of the internal defect inspection step of the sixth embodiment, the inspection light also reaches the region of S3, S4, S5, and S6. Therefore, in the case of the sixth embodiment, the internal defect inspection can be performed on all the regions in the substrate 10 by slightly increasing the light intensity of the inspection light source. Further, the matters relating to the method for producing a glass substrate for a mask base, the method for producing a mask substrate, and the method for producing an exposure mask are the same as those in the fourth embodiment.

(Embodiment 7)

The seventh embodiment differs from the fourth embodiment in that (3) before the polishing step of the glass substrate for the mask base, the internal defects of the glass substrate are inspected after the (4) manufacturing step of the mask substrate. The step is the defect inspection step.

The internal defect inspection of the glass substrate is performed on the photomask substrate manufactured by the (4) photomask substrate manufacturing step by the same method as (2) the internal defect inspection step of the photomask base glass substrate. The size of the glass substrate of the mask base is manufactured with a vertical and horizontal dimension of about 152 mm × 152 mm × 6.35 mm and a chamfering amount k of 0.6 mm. If an error is added, the specific area where the inspection light is to be reached should be set to a minimum. 132 mm × 132 mm × 6.4 mm, the divergence angle θc of the inspection light may be 4.8 or more. Further, the divergence angle is considered in consideration of the risk of damage to the substrate due to a decrease in the light intensity of the inspection light due to the divergence angle diverging by the concave lens, and the increase in the light intensity of the inspection light source. Θc is preferably 7.0 or less.

According to the seventh embodiment, the same effects as those in the fourth embodiment can be obtained. Further, since the fluorescent light is reflected at the interface between the main surface 11 of the substrate and the film, the effect of more easily identifying the presence or absence of the fluorescence can be obtained. Further, as a method of introducing the inspection light into the glass substrate 10 of the reticle base, as shown in the fifth embodiment, the divergent light of the inspection light can be sequentially introduced from the end surface 13 side and from the end surface 14 side. Further, as a method of introducing the inspection light into the glass substrate 10 of the mask base, as in the third embodiment, the inspection light of the divergent light having a divergence angle θc of 0.7 or more may be used, from the end surface 13 side and the self-end surface. The two sides of the 14 side sequentially introduce inspection light.

It is also possible to perform the same internal defect inspection as that performed on the mask substrate by the exposure mask manufactured by the (5) manufacturing step of the exposure mask. Further, the fluorescent light generated by the internal defect by the irradiation of the inspection light has a large change in the amount of light depending on the intensity of the inspection light or the internal defect, and therefore, if it is necessary to more reliably exclude the internal defect, The internal defect inspection is performed at any stage of the stage of grinding the glass substrate, the stage of polishing the glass substrate for the reticle substrate, the stage of the reticle substrate, and the stage of the exposure reticle.

The present invention has been described above with reference to a few embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made within the scope of the invention.

The priority of Japanese Patent Application No. 2009-4085, filed on Jan. 9, 2009, and Japanese Patent Application No. 2009-16026, filed on Jan. 27, 2009. The content is fully incorporated herein.

Industrial availability

The present invention can be used for an exposure mask which is used as a transfer mask for ultrafine patterns when manufacturing a super LSI (Large Scale Integration) or the like, and a mask base used as a material for the exposure mask. And the manufacture of a glass substrate for a reticle substrate used as a material of the reticle substrate.

10. . . Glass substrate for mask base

11,12. . . Main surface (surface and back)

13, 14, 15, 16. . . End face

13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b. . . Chamfered surface

20. . . Glass substrate defect inspection device

twenty one. . . Laser device

twenty two. . . XYZ platform

twenty three. . . CCD camera

27. . . computer

28. . . Concave lens

B, D, E, F, H, J. . . Boundary surface

Be, Bf, Bj, De, Df, Dh. . . Intersection line

C. . . Intermediate face

C1, C2. . . Intermediate location

L. . . Check light

L1~L6. . . Light

Θg. . . slope

1 is an explanatory view of a defect inspection method of a glass substrate for a reticle base;

Figure 2 is a perspective view of the glass substrate of Figure 1;

3 is an explanatory view showing a defect inspection step in the method of manufacturing a glass substrate for a mask base according to Embodiment 1 of the present invention;

Figure 4 is an enlarged view of a portion A of Figure 3;

FIG. 5 is a view showing a configuration of a device for performing a defect inspection step in a method of manufacturing a glass substrate for a reticle base according to Embodiment 1 of the present invention;

6(A) and (B) are explanatory diagrams of defect detection;

Fig. 7 is an explanatory view showing a defect inspection step in a method of manufacturing a glass substrate for a mask base according to Embodiment 2 of the present invention;

FIG. 8 is an explanatory view showing a defect inspection step of the glass substrate for a reticle base according to Embodiment 4 of the present invention; FIG.

Figure 9 is an enlarged view of a portion A of Figure 8;

Figure 10 is an explanatory diagram of a divergence angle θc;

Figure 11 is a view showing the configuration of a device for performing a defect inspection step of a glass substrate for a reticle base according to Embodiment 4 of the present invention;

Figure 12 is an explanatory view showing a defect inspection step of the glass substrate for a reticle base according to Embodiment 5 of the present invention; and

Fig. 13 is an explanatory view showing a defect inspection step of the glass substrate for a mask base according to the sixth embodiment of the present invention.

10. . . Glass substrate for mask base

11,12. . . Main surface (back surface)

13, 14. . . End face

13a, 13b, 14a, 14b. . . Chamfered surface

B, D, E, F, H, J. . . Boundary surface

Be, Bf, Bj, De, Df, Dh. . . Intersection line

C. . . Intermediate face

C1, C2. . . Intermediate location

L. . . Check light

L1~L6. . . Light

Θg. . . slope

Claims (23)

A method for manufacturing a glass substrate for a reticle base, comprising the steps of: preparing a substrate, preparing a glass substrate for a reticle base having two main surfaces and four end faces; and a defect inspection step, One end of the glass substrate is introduced with inspection light of substantially parallel light having a wavelength of 200 nm or less to inspect an internal defect; and the defect inspection step is performed by tilting the inspection light toward a main surface side from one end surface and introducing the light into the glass substrate. The inspection light is introduced into the glass substrate by tilting the inspection light toward the end surface opposite to the one end surface, and the inspection light is used to inspect the internal defects of the glass substrate. Regarding the presence or absence of fluorescence, a glass substrate in which no fluorescence generated by internal defects was detected was selected. The method for producing a glass substrate for a reticle base according to claim 1, wherein the glass substrate has a chamfered surface formed at a corner portion where the two main surfaces intersect the four end faces. The method for producing a glass substrate for a reticle base according to claim 1 or 2, wherein in the defect inspection step, the inspection light is introduced from the one end surface and the end surface opposite to the one end surface, thereby further inspecting the light relative to all the main The surface was introduced into the glass substrate from any end surface without inclination, and the presence or absence of the fluorescence generated by the above internal defects was examined. The method for producing a glass substrate for a mask base according to claim 1 or 2, wherein the inspection light system introduced to the glass substrate has a specific divergence angle astigmatism. The method for producing a glass substrate for a reticle base according to claim 4, wherein the inspection light is converted into divergent light from the end surface into the glass substrate by a concave lens or a concave mirror. A method of producing a glass substrate for a mask base according to claim 5, wherein the concave lens is disposed in a cylindrical lens before the end surface. A method of producing a glass substrate for a mask base according to claim 5, wherein the concave mirror is disposed on a cylindrical concave mirror before the end surface. A method of manufacturing a reticle substrate, comprising: a main surface of a glazing substrate for a reticle substrate manufactured by the method for producing a glazing substrate for a reticle substrate according to any one of claims 1 to 7 Forming a film for pattern formation. A method of manufacturing an exposure mask, comprising the steps of: forming a thin film for exposure on a film for pattern formation of a mask substrate manufactured by the method for manufacturing a mask base according to claim 8 pattern. A method for manufacturing a reticle substrate, comprising the steps of: preparing a substrate, preparing a thin glass substrate for a reticle base having two main surfaces and four end faces; and forming a film on the glass substrate a film for forming a pattern on the main surface; and a defect inspection step of inspecting the internal defect by introducing inspection light of substantially parallel light having a wavelength of 200 nm or less from one end toward the glass substrate And the defect inspection step is such that the inspection light is inclined toward a main surface side and introduced into the glass substrate from one end surface, thereby inclining the inspection light toward the main surface side opposite to the one main surface from the one end surface The end surface is introduced into the glass substrate, and the presence or absence of the fluorescent light generated by the internal defects of the glass substrate is inspected by the inspection light, and the mask base on which the fluorescent light generated by the internal defect is not detected is selected. A method for manufacturing an exposure mask, comprising: a substrate preparation step of preparing a thin glass substrate for a mask base comprising two main surfaces and four end surfaces; and a film forming step on the glass substrate a main film forming a film for pattern formation; a fine pattern forming step of forming a fine pattern for exposure on the film; and a defect inspection step of introducing substantially parallel light having a wavelength of 200 nm or less from one end toward the glass substrate Light is used to detect internal defects; and the defect inspection step is such that the inspection light is inclined toward a main surface side and introduced into the glass substrate from one end surface, thereby tilting the inspection light toward the main surface side opposite to the one main surface. The end surface facing the one end surface is introduced into the glass substrate, and the presence or absence of the fluorescent light generated by the internal defect of the glass substrate is inspected by the inspection light, and the fluorescent light generated by the internal defect is not selected. Exposure light cover. A method for manufacturing a glass substrate for a reticle base, comprising the steps of: preparing a substrate, preparing a glass substrate for a reticle base having two main surfaces and four end faces; and a defect inspection step, One end faces the glass substrate to introduce inspection light having a wavelength of 200 nm or less to inspect internal defects; and the defect inspection step uses divergent light having a divergence angle of 7.0 or less as inspection light, and the inspection light reaches the glass substrate to be inspected. The entire specific area is examined for the presence or absence of fluorescence generated by internal defects, and a glass substrate in which no fluorescence generated by internal defects is detected is selected. The method for producing a glass substrate for a reticle base according to claim 12, wherein the glass substrate has a chamfered surface formed at a corner portion where the two main surfaces intersect the four end faces. The method for producing a glass substrate for a mask base according to claim 12, wherein the inspection light has a divergence angle reaching the entire specific region when being introduced into the glass substrate from one end surface. The method for manufacturing a glass substrate for a reticle substrate according to claim 12, wherein the inspection light has a divergence angle when introduced from the one end surface into the glass substrate: by the one end surface and the end surface opposite thereto In a specific region in which the intermediate surface is divided into two, the entire region of the region close to the side of the one end face is not reached, and the entire region of the region away from the side of the one end face is reached. The method for producing a glass substrate for a reticle base according to claim 12, wherein the inspection light is introduced into the glass substrate from one end surface to check the presence or absence of fluorescence, and then the inspection light is opposed to the one end surface. The end surface is introduced into the glass substrate to check the presence or absence of fluorescence. The method for producing a glass substrate for a mask base according to claim 12 or 13, wherein the inspection light is introduced into the glass substrate from the end surface by a concave lens or a concave mirror to convert the parallel light into divergent light. A method of producing a glass substrate for a mask base according to claim 17, wherein the concave lens is disposed in a cylindrical lens before the end surface. A method of producing a glass substrate for a reticle base according to claim 17, wherein the concave mirror is disposed on a cylindrical concave mirror before the end surface. A method of manufacturing a reticle substrate, comprising: a main surface of a glazing substrate for a reticle substrate manufactured by the method for producing a glazing substrate for a reticle substrate according to any one of claims 12 to 19 Forming a film for pattern formation. A method of manufacturing an exposure mask, comprising the steps of: forming a thin film for exposure on a film for pattern formation of a mask substrate manufactured by the method for manufacturing a mask base according to claim 20; pattern. A method for manufacturing a reticle substrate, comprising the steps of: preparing a substrate, preparing a thin glass substrate for a reticle base having two main surfaces and four end faces; and forming a film on the glass substrate Main surface forming a pattern a film for use; and a defect inspection step of inspecting an internal defect by introducing inspection light having a wavelength of 200 nm or less from one end toward the glass substrate; and the defect inspection step uses divergent light having a divergence angle of 7.0 or less as inspection light. The inspection light reaches the entire specific area to be inspected in the above-mentioned glass substrate to check the presence or absence of the fluorescent light generated by the internal defect, and the reticle base on which the fluorescent light generated by the internal defect is not detected is selected. A method for manufacturing an exposure mask, comprising: a substrate preparation step of preparing a thin glass substrate for a mask base comprising two main surfaces and four end surfaces; and a film forming step on the glass substrate a main film forming a film for pattern formation; a fine pattern forming step of forming a fine pattern for exposure on the film; and a defect inspection step of inspecting an internal defect by introducing inspection light having a wavelength of 200 nm or less from one end toward the glass substrate; In the defect inspection step, the divergent light having a divergence angle of 7.0° or less is used as the inspection light, and the inspection light reaches the entire specific region to be inspected in the glass substrate to check the presence or absence of the fluorescent light generated by the internal defect. An exposure mask that does not detect fluorescence generated by internal defects is selected.