JP5346243B2 - Mask blank glass substrate manufacturing method, mask blank manufacturing method, exposure mask manufacturing method, and pattern transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a defect-free product by reliably detecting inner defects in the whole region inside a glass substrate including a region close to the surface. <P>SOLUTION: The method for manufacturing the glass substrate for mask blank includes: a primary shaping step of processing a sheet glass into a shape of a glass substrate for a mask blank; a defect inspection step of polishing one end face of the glass substrate into a mirror face, introducing an inspection beam at a wavelength of not more than 200 nm into the glass to inspect whether fluorescent light emitting from an inner defect is present or not, and selecting a glass substrate with no detection of fluorescent light; and a secondary shaping step of grinding and polishing the selected glass substrate. The width in a direction across both of the main surfaces of a region, where the inspection beam at an intensity necessary to emit fluorescent light from an inner defect in the glass substrate can reach in the defect inspection step, is larger than the thickness between both of the main surfaces of the glass substrate after the secondary shaping step. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a mask blank glass substrate manufacturing method, a mask blank manufacturing method, and an exposure mask manufacturing method, each of which includes a defect inspection process for a mask blank glass substrate that detects an internal defect of the mask blank glass substrate. .

  In recent years, with the miniaturization of semiconductor devices, light having a short wavelength such as an ArF excimer laser (exposure wavelength 193 nm) has been used as exposure light in the photolithography technique. Also in the technical field of exposure masks used in photolithography technology and mask blanks for manufacturing this exposure mask, a light-shielding film capable of blocking light against the exposure light having the short wavelength described above, and a phase. A phase shift film to be changed has been rapidly developed, and various film materials have been proposed.

  By the way, it is required that the mask blank glass substrate and the synthetic quartz glass substrate for manufacturing the mask blank glass substrate are free from defects such as foreign matters and bubbles. Patent Document 1 discloses an internal defect (foreign matter or bubble) present in a glass substrate by detecting fluorescence generated from the internal defect of the glass substrate when inspection light having a wavelength of 200 nm or less is introduced into the glass substrate. And the like are disclosed.

JP 2007-86050 A

  However, it has been found that even if the glass substrate is determined to have no internal defects by the above-described defect detection method, defects may remain particularly near the vicinity of the two main surfaces. As a result of investigating the cause of the inventor, the following has been found.

  FIG. 4 is an explanatory view of a conventional defect inspection method for a mask blank glass substrate, and FIG. 5 is a perspective view of the glass substrate 10 in FIG. 4 and 5, reference numeral 10 denotes a glass substrate to be inspected. The glass substrate 10 has two main surfaces 11 and 12 and four end surfaces 13, 14, 15, and 16. Chamfered surfaces 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b are formed at corners where the two main surfaces 11, 12 and the four end surfaces 13, 14, 15, 16 intersect. .

The inspection light L is irradiated perpendicularly to the end face 13 from the left side in the drawing and introduced into the glass substrate 10. The inspection light L is a width (vertical width) t _{L that} is slightly larger than the thickness tg of the glass substrate 10.
And substantially parallel light. Therefore, the inspection light L is actually introduced into the inside through the end surface 13 and the chamfered surfaces 13a and 13b. The horizontal width (the end face 13 and the two major surfaces parallel to the width) of the inspection light L also has a width of about substantially equal to the vertical width t _L. Accordingly, the entire glass substrate is inspected by introducing inspection light to the entire glass substrate by moving the glass substrate in a direction parallel to the end face 13 and the two main surfaces.

Here, the inspection light L is incident from the end face 13 substantially perpendicularly, but the light introduced into the inside through the chamfered faces 13a and 13b is incident at an angle of about 45 ° with respect to the chamfered faces. 10 passes through the regions S1 and S2. For this reason, when incident from the chamfered surfaces 13a and 13b, reflection and refraction occur at these surfaces, and the intensity of the inspection light incident from these surfaces and passing through the regions S1 and S2 is incident from the end surface 13 vertically. Therefore, it is considered that the intensity of the inspection light passing through another region is considerably weakened. As a result, it is considered that the intensity of the inspection light applied to the defects Ka, Kb, etc. in the regions S1, S2 is not sufficient, and the fluorescence generated from the defects is not sufficient.

  The present invention has been made under the above-mentioned background, and the object thereof is a method for manufacturing a glass substrate for a mask blank and a mask blank for manufacturing a glass substrate for a mask blank having no internal defects near the main surface. An object of the present invention is to provide a manufacturing method of the above and a manufacturing method of an exposure mask.

Means for solving the above-described problems are as follows.
1st means The primary shape processing process which grinds the plate-like glass cut out from the glass ingot, and processes it into the shape of the glass substrate for mask blanks which has two main surfaces and four end faces,
A mirror polishing step of mirror polishing at least one end surface of the glass substrate;
An inspection light having a wavelength of 200 nm or less is introduced into the glass substrate from the one end surface of the glass substrate that has been mirror-polished, the presence or absence of fluorescence generated from an internal defect is inspected by the inspection light, and a glass substrate in which no fluorescence is detected is obtained. Defect inspection process to select,
A secondary shape processing step of grinding and polishing the two main surfaces and the four end surfaces of the selected glass substrate;
In the defect inspection step, the width in the direction between both main surfaces of the region where the inspection light having the intensity necessary for generating fluorescence from the internal defect in the glass substrate reaches the two main surfaces of the glass substrate after the secondary shape processing step. The manufacturing method of the glass substrate for mask blanks characterized by being larger than the thickness between surfaces.
Second means The glass substrate after the secondary shape processing step has a chamfered surface formed at a corner where two main surfaces and the four end faces intersect with each other. A method for producing a mask blank glass substrate.
Third means The glass substrate to be inspected in the defect inspection step has a chamfered surface formed at a corner where two main surfaces and the four end surfaces intersect, and the width of the end surface in the direction between both main surfaces. Is larger than the thickness between both main surfaces of the glass substrate after the secondary shape processing step, The method for producing a mask blank glass substrate according to either the first or second means.
4th means It provided with the process of forming the thin film for pattern formation in the main surface of the glass substrate for mask blanks manufactured by the manufacturing method of the glass substrate for mask blanks concerning either of the 1st to 3rd means A method for producing a mask blank characterized by the above.
5th means Manufacturing of the exposure mask characterized by having the process of forming the transcription | transfer pattern for exposure in the said thin film for pattern formation of the mask blank manufactured by the manufacturing method of the mask blank concerning 4th means Method.

According to the above-described means, the defect inspection step is performed between the primary shape processing step and the secondary shape processing step, and further, in the defect inspection step, the inspection light reaches at an intensity at which fluorescence is generated from the internal defect. Insufficient inspection of internal defects in the defect inspection process by making the width in the direction between the two main surfaces of the region in the glass substrate larger than the thickness between the two main surfaces of the glass substrate after the secondary shape processing step Therefore, the mask blank glass substrate having no internal defects can be manufactured.

It is explanatory drawing of the manufacturing method of the glass substrate for mask blanks concerning embodiment of this invention. It is a figure which shows the apparatus structure for test | inspecting the internal defect of a glass substrate. It is explanatory drawing of an internal defect detection. It is explanatory drawing of the defect inspection method of the conventional glass substrate for mask blanks. It is a perspective view of the glass substrate 10 in FIG.

  FIG. 1 is an explanatory diagram of a method for manufacturing a mask blank glass substrate according to an embodiment of the present invention, and FIG. 2 is an apparatus configuration for performing a defect inspection process for the mask blank glass substrate according to the embodiment of the present invention. FIG. 3 is an explanatory diagram of defect detection. Hereinafter, a mask blank glass substrate manufacturing method, a mask blank manufacturing method, and an exposure mask manufacturing method according to embodiments of the present invention will be described with reference to these drawings. In addition, since the glass substrate for mask blanks which is the inspection target of the present embodiment is the same as the glass substrate for mask blanks which is the target of the above-described conventional mask blank glass substrate inspection method, Are described with the same reference numerals. In the following description, a method for manufacturing a mask blank glass substrate and a method for manufacturing a mask blank will be described together in the course of describing a method for manufacturing an exposure mask.

  An exposure mask manufacturing method according to the embodiment includes (1) a mask blank glass substrate manufacturing process, (2) a mask blank manufacturing process, and (3) an exposure mask manufacturing process. Among the above steps, the greatest feature of the present embodiment is (1) a method for manufacturing a glass substrate for mask blank, and other steps use known steps. Description will be made focusing on the manufacturing method of the glass substrate for mask blanks with the minimum necessary.

(1) Manufacturing process of mask blank glass substrate a. Sheet glass grinding step From a synthetic quartz glass ingot produced by a known method (for example, see JP-A-8-31723, JP-A-2003-81654, etc.), both the vertical dimension and the horizontal dimension are a0 = 152. A plate-like body having a thickness of .40 mm and a thickness of t0 = 7.28 mm is cut out to obtain a synthetic quartz plate-like glass (see FIG. 1A). This plate-like glass (glass substrate 10) has two main surfaces 11, 12 facing each other and four end surfaces 13, 14, 15, 16 orthogonal to the front and back surfaces. At this stage, no chamfered surface has yet been formed.

b. Primary chamfering process Step Chamfered surfaces 13 a, 13 b, 14 a, and chamfered surfaces 13 a, 13 b, 14 a, and the like are used at the corners where the main surfaces 11, 12 of the glass substrate 10 intersect the four end surfaces 13, 14, 15, 16. 14b, 15a, 15b, 16a, 16b are formed (see FIG. 1B). The dimension m1 in the direction between the main surfaces 11 and 12 of each chamfered surface after chamfering (direction between both main surfaces: a direction perpendicular to both main surfaces) is m1 = 0.43 mm. In addition, the length tm1 between the corner portion that intersects the chamfered surface on the main surface 11 side of each end surface and the corner portion that intersects the chamfered surface on the main surface 12 side is tm1 = 6.42 mm.

c. Main surface lapping process After forming the chamfered surface, the main surfaces 11 and 12 are lapped using a conventional processing apparatus (see FIG. 1C). After this lapping of both main surfaces, the thickness t between the two main surfaces of the glass substrate
1 is t1 = 6.90 mm. As a result, the dimension m2 of the chamfered surface in both main surface directions is m2 = 0.24 mm. Here, the surface roughness Ra (arithmetic mean roughness) of the main surfaces 11 and 12 is about 0.5 μm or less.
As described above, the primary shape processing step (“a. Plate glass” in the order of “a. Plate glass grinding step”, “b. Primary chamfering step”, “c. Main surface lapping grinding step”. The “grinding step” is not included in the primary shape processing step, and may be an independent step).

d. Mirror surface polishing process After the main surface lapping process, the end surface (one end surface) for introducing inspection light is polished into a mirror surface so that ArF excimer laser light, which is inspection light during the defect inspection process, can be introduced into the glass substrate. To. (See FIG. 1 (d)). Here, all four end faces are mirror-polished, and as a result, the dimension in the direction between the end faces 13 and 14 (distance between both end faces in the direction perpendicular to the end faces 13 and 14 = distance between the end faces 13 and 14). In addition, the dimension in the direction between the end faces 15 and 16 (distance between both end faces in the direction perpendicular to the end faces 15 and 16 = distance between the end faces 15 and 16) is a1 = 152.35 mm. Other dimensions are substantially unchanged. The surface roughness Ra (arithmetic average roughness) of the mirror-polished end surface is about 0.03 μm or less. Next, the mask blank glass substrate 10 thus obtained is supplied to a defect inspection process which is the next process.

e. Defect Inspection Process In this process, the glass substrate 10 obtained as described above is inspected for the presence of internal defects by a defect inspection apparatus described below, and a glass substrate having no internal defects is selected (FIG. 1 (e)). reference). The defect inspection method used here is the method described in Patent Document 1 already described. That is, when an inspection light having a wavelength of 200 nm or less is introduced into the glass substrate 10, fluorescence generated from the internal defects of the glass substrate 10 is detected to detect internal defects (foreign matter, bubbles, etc.) present in the glass substrate 10. ) Is detected. FIG. 2 is a diagram showing a device configuration for inspecting an internal defect of the glass substrate 10, and FIG. 3 is an explanatory diagram of defect detection. The internal defect inspection process will be described below with reference to FIGS.

  In FIG. 2, the code | symbol 20 is a defect inspection apparatus of a glass substrate. The glass substrate defect inspection apparatus 20 includes a laser device 21 for generating inspection light L and irradiating the glass substrate 10, and the glass substrate 10 is placed on the glass substrate 10 and moved in the X, Y, and Z directions, respectively. An XYZ stage 22 for sending position information, a CCD camera 23 for detecting fluorescence generated on the glass substrate 10, image information from the CCD camera 23, position information from the XYZ stage 22, etc. are input to perform predetermined processing. And a computer 27. The laser device 21 is provided on the side of the mirror-polished end face 13 of the glass substrate 10 placed on the XYZ stage 22. The inspection light L emitted from the laser device 21 is introduced into the glass substrate 10 through the end face 13.

The inspection light emitted from the laser device 21 is pulsed ArF excimer laser light (exposure wavelength: 193 nm) having a beam shape of 7.0 mm × 4.0 mm, a power of 2 mJ, and a frequency of 400 Hz. The glass substrate 10 can be placed and moved in the XYZ directions, the glass substrate is moved to a desired position, and the position information is sent to the computer 27. In the case of performing this defect inspection, the glass substrate 10 is placed at the inspection start position, and then the inspection light L is introduced into the glass substrate 10 by the laser device 21, and images of the fluorescence Lkc and Lkd at that time are introduced. Is imaged by the CCD camera 23, and the image information and the position information are sent to the computer 27 and stored. Next, the XYZ stage 22 is driven to move the glass substrate 10 in the Y direction by the width of the inspection light L. Similarly, the inspection light L is irradiated, and images of the fluorescence Lkc and Lkd at that time are CCD cameras. 23, and the image information and the position information are sent to the computer 27. By repeating this operation, the inspection light L is introduced from all regions from one end (end face 15 side) of the end face 13 to the other end (end face 16 side).

  As a result, the inspection light L is irradiated to almost the entire region in the glass substrate 10 and the fluorescent image in the glass substrate 10 is accumulated. The CCD camera 23 is disposed on one main surface 11 side (upper side in the drawing) of the main surfaces, and creates an image based on information of light emitted from the glass substrate 10. That is, the fluorescence Lkc and Lkd generated from the internal defects Kc and Kd of the glass substrate 10 are detected, an image of the fluorescence is taken, and the image information is sent to the computer 27. In this embodiment, a so-called monochrome camera is used as the CCD camera 23.

  The computer 27 inputs an image from the CCD camera 23, processes the image at each position in the Y direction of the glass substrate 10, and at each position in the Y direction of the glass substrate 10, the light Lkc received by the CCD camera 23 is received. The light amounts (intensities) of Lkd and Lg are analyzed in relation to the X direction position of the glass substrate 10. That is, when the light quantity of the light Lkc, Lkd, and Lg has a local light quantity that is equal to or greater than a predetermined threshold, the computer 27 emits the light Lkc and Lkd with a local light quantity that is greater than or equal to the predetermined threshold value due to the internal defects Kc and Kd. It is determined that the internal defects Kc, Kd are located from the positions of the internal defects Kc, Kd (positions in the X direction and Y direction on the glass substrate 10), and the local amounts of light Lkc, Lkd emitted from the internal defects Kc, Kd. The types of defects Kc and Kd (local striae, contents, and foreign substances) are specified and detected.

  For example, when local striae or contents exist as the internal defect Kc in the glass substrate 10, ArF excimer laser light from the laser irradiation device 21 is introduced into the glass substrate 10. As shown in FIG. 5A, the object emits light Lkc having a local light quantity equal to or greater than a predetermined threshold (1000 counts), and the region other than the local striae or contents of the synthetic quartz glass substrate 4 emits light Lg. The computer 27 determines that the internal defect Kc is a local striae or a foreign substance from the shape of the light Lkc having a local light amount equal to or greater than a predetermined threshold by performing image processing and analyzing the light Lkc and Lg received by the CCD camera 23. If the local striae or contents are present at a position where the light Lkc having a local light quantity equal to or greater than the predetermined threshold is emitted, the local striae or contents are detected together with the position. Here, in FIG. 3A, the horizontal axis indicates the X-direction position of the glass substrate 10, and the vertical axis indicates the light amounts (intensities) of the light Lkc and Lg.

  Further, when an extraneous matter exists as an internal defect Kd in the glass substrate 10, ArF excimer laser light is introduced into the glass substrate 10 from the laser irradiation device 21, whereby the extraneous matter is shown in FIG. As described above, a light Lkd having a local light amount equal to or greater than a predetermined threshold (1000 counts) is emitted in a predetermined range (for example, 20 to 50 mm), and a region other than the foreign matter of the synthetic quartz glass substrate 4 emits light Lg. The computer 27 performs image processing on the light Lkd and Lg received by the CCD camera 23 and analyzes them to determine the internal defect Kd as a foreign substance from the shape of the light Lkd having a local light amount equal to or greater than a predetermined threshold, and Assuming that the extraneous matter is present at a position where light Lkd having a local light quantity equal to or greater than a predetermined threshold is generated, the extraneous matter is detected together with the position. Here, also in FIG. 3B, the horizontal axis indicates the X-direction position of the glass substrate 10, and the vertical axis indicates the detected light amount (intensity).

  The glass substrate defect inspection apparatus 20 selects the glass substrate 10 in which the fluorescence Lkc and Lkd are not detected, that is, the internal defects Kc and Kd are not detected, and supplies the selected glass substrate 10 to the next secondary grinding process.

f. Secondary grinding process Using a conventional processing apparatus, the glass substrate 10 selected in the defect inspection process is ground to increase the chamfered surface and grind the end face (see FIG. 1 (f)). .
The dimension m3 of the chamfered surfaces after the secondary shape processing step in both main surface directions is m3 = 0.65 mm. In addition, the length tm2 between the corner portion of each end face that intersects the chamfered surface on the main surface 11 side and the corner portion that intersects the chamfered surface on the main surface 12 side is tm2 = 5.60 mm. Further, the dimension in the direction between the end faces 13 and 14 and the dimension in the direction between the end faces 15 and 16 are both a2 = 152.15 mm.

g. End surface / chamfered surface polishing step Each end surface and the chamfered surface are polished by using a conventional processing apparatus on the glass substrate 10 subjected to the secondary grinding process (see FIG. 1G).
The dimension m4 in the direction of both main surfaces of the chamfered surface after the end face / chamfered surface polishing step is m4 = 0.675 mm. Further, the length tm3 between the corner portion of each end face that intersects the chamfered surface on the main surface 11 side and the corner portion that intersects the chamfered surface on the main surface 12 side is tm3 = 5.55 mm. Both the dimension between the end faces 13 and 14 and the dimension between the end faces 15 and 16 are a4 = 152.10 mm.

h. Tertiary grinding process The main surfaces 11 and 12 are ground using the conventional processing apparatus with respect to the glass substrate 10 by which the end surface and the chamfering surface grinding | polishing process were performed (refer FIG.1 (h)).
After this tertiary grinding process, the thickness t2 between the two main surfaces of the glass substrate is t2 = 6.40 mm. Further, the dimension m5 of the chamfered surface in both main surface directions is m5 = 0.425 mm.

i. Precision Polishing Process In this precision polishing process, each end face and chamfered surface are polished using a conventional processing apparatus, and the main surfaces 11 and 12 are polished precisely using a conventional double-side polishing apparatus (FIG. 1 (i )reference). A mask blank glass substrate is obtained by this precision polishing.

The thickness t3 in both main surface directions of the glass substrate for mask blank after this precision polishing is t3 = 6.35 mm. The dimension m6 in the thickness direction of the chamfered surface is m6 = 0.39 mm. The distance tm4 between the chamfered surface of the front surface 11 and the chamfered surface of the back surface 12 is tm4 = 5.57 mm. Both the vertical dimension and the horizontal dimension are a5 = 152.0 mm.
As described above, the secondary shape machining process is performed in the order of “f. Secondary grinding process”, “g. End face / chamfering surface grinding process”, and “i. Precision grinding process”.

  The length tm1 between the corners intersecting the chamfered surface on the main surface 11 side of each end surface of the glass substrate 10 and the corner intersecting the chamfered surface on the main surface 12 side in the defect inspection step is tm1 = 6. The inspection light reaches the inside of this tm1 width region. On the other hand, the thickness t3 in both main surface directions of the mask blank glass substrate 10 subjected to the secondary shape processing step is t3 = 6.35 mm, which is smaller than tm1. That is, the region in the glass substrate 10 where the inspection light does not reach during the defect inspection process is removed in the secondary shape processing step, and the mask blank glass substrate 10 manufactured in this embodiment has an internal structure. It can be guaranteed that there are no defects.

(2) Mask Blank Manufacturing Method Next, a mask pattern forming thin film (halftone film) is formed on the main surface 11 of the mask blank glass substrate 10 obtained as described above by a known sputtering apparatus, for example, DC. A half-tone type phase shift mask blank as a mask blank is obtained by using a magnetron sputtering apparatus or the like.

(3) Transfer Mask Manufacturing Method Next, a halftone phase shift as an exposure mask is formed by forming a pattern on the halftone film of the mask blank (halftone type phase shift mask blank) by a known pattern forming method. Get a mask. That is, after applying a resist to the surface of the halftone film, a heat treatment is performed to form a resist film, a predetermined pattern is drawn and developed on the resist film, a resist pattern is formed, and the resist pattern is masked Then, the halftone film is dry-etched to form a halftone film pattern, the resist pattern is removed, and a transfer mask having the halftone film pattern formed on the glass substrate 10 is obtained. As a material used for this halftone film, a material mainly composed of a transition metal silicide composed of transition metal silicide such as molybdenum, tantalum, tungsten, zirconium and the like and silicon is oxidized, nitrided, or oxynitrided. It is done. Further, the halftone film has a laminated structure of two or more layers of a transmittance adjusting layer that mainly adjusts the transmittance for exposure light and a phase adjusting layer that mainly adjusts the phase difference for the exposure light transmitted through the film. Also good.

  The transfer mask produced as described above was placed on the mask stage of an exposure apparatus such as a scanner, and the pattern was transferred to the transfer object such as a resist film on the semiconductor wafer. When the ArF exposure light irradiated from the light passes through the glass substrate of the transfer mask, there is no abnormality in the transfer to the transfer object due to the fluorescence from the internal defect, and the transfer pattern can be accurately formed. I was able to transcribe.

  According to the above embodiment, the defect inspection step is performed between the primary shape processing step and the secondary shape processing step, and further, the region in the glass substrate where the inspection light reaches with an intensity at which fluorescence is generated from the internal defect By making the width in the direction of both main surfaces of the glass substrate larger than the thickness between the two main surfaces of the glass substrate after the secondary shape processing step, it becomes a shadow of the chamfered surface in the conventional glass substrate defect inspection process. The regions where the intensity of the light L is weak (S1, S2 in FIG. 4) are surely removed in the secondary shape processing step. Therefore, by removing the regions (S1 and S2 in FIG. 4) where the minute defects may exist, it is possible to reliably manufacture a glass substrate for a mask blank having no internal defects.

  In this embodiment, the example in which the CCD camera 23 that receives the light Lkc, Lkd, and Lg emitted from the internal defects Kc and Kd is arranged on the main surface 11 side in the defect inspection process is shown. , ArF excimer laser light may be disposed on the side of the end face other than the end faces 13 and 14 for introducing the laser beam. Alternatively, ArF excimer laser light may be introduced from the end face 15 and the end face 16 as long as it is polished to such an extent that inspection light can be introduced.

  In this embodiment, chamfered surfaces 13a, 13b, 14a, 14b, 15a, 15b, 16a, and 16b are formed on the glass substrate 10 that performs the defect inspection process, respectively, but the primary chamfering process is not performed. That is, a mirror polishing process is performed without forming a chamfered surface, at least one of the end surfaces is mirror polished, and inspection light is introduced from the end surface mirror-polished in the defect inspection process to inspect internal defects. Good. In this way, the width in the direction of both main surfaces of the region where the inspection light having the intensity necessary for fluorescence to be emitted from the internal defect can be increased.

  In this embodiment, a region where the inspection light in the glass substrate 10 reaches with an intensity necessary for fluorescence to be emitted from an internal defect is produced using the glass substrate 10 in the direction parallel to the main surfaces 11 and 12. It suffices that a range of 132 mm square from the center of the main surface, which is a region where a transfer pattern is formed on the thin film for forming a mask blank pattern, covers at least. In order to inspect an internal defect near the 132 mm square boundary with higher accuracy, it is preferable to cover a 142 mm square range from the center of the main surface, and more preferably, a 146 mm square range.

In addition, it is not necessary to form a region that reaches with an intensity necessary for fluorescence to be emitted from an internal defect only with inspection light introduced from one end surface of the glass substrate 10, and two opposing end surfaces (end surfaces 13, 14 or end faces 15 and 16) may be formed simultaneously or separately by introducing inspection light. In this case, the region that reaches with the intensity required for fluorescence to be emitted from the internal defect by the inspection light introduced from the one end face may be wider than the intermediate point between the opposing end faces. As a result, the light intensity of the inspection light to be introduced can be made weaker than when the region is formed by inspection light from only one end surface, and damage to the glass substrate due to the introduction of the inspection light can be reduced. it can.

  In this embodiment, the case where the exposure light source is an ArF excimer laser has been described. However, the light may be light having a wavelength of 200 nm or less, preferably 100 nm to 200 nm, and may be an F2 excimer laser. In addition, in order to obtain the same wavelength as the ArF excimer laser or the F2 excimer laser, the light having a central wavelength that is the same as that of the ArF excimer laser or the F2 excimer laser may be used by dispersing light from a light source such as a heavy water (D2) lamp. .

  In this embodiment, the CCD camera 23 is used as a color camera, the internal defect of the glass substrate 10 and a region other than the internal defect are emitted and photographed by receiving fluorescence, and the computer 27 captures an image of the CCD camera 23. Image processing may be performed for each color of red, green, and blue, and the internal defect 16 may be detected from the intensity (light quantity) distribution of light subjected to image processing for each color. In this case, the computer 27 may detect an internal defect from information such as the color and wavelength of light subjected to image processing for each color. Moreover, you may implement an internal defect detection at the final stage of the manufacturing process of the glass substrate for mask blanks.

  In this embodiment, it has been described that the CCD camera 23 receives the fluorescence emitted from the internal defect of the glass substrate 10 and the region other than the internal defect. However, the spectroscope receives these lights and the internal defect is detected. Internal defects may be detected by measuring spectral characteristics (wavelength and intensity) and intensity (light quantity) distribution of light Lkc, Lkd, and Lg.

  In this embodiment, the case of a halftone phase shift mask blank in which a halftone film is formed on the mask blank glass substrate 10 has been described. However, the present invention is not limited to this. For example, a halftone phase shift mask blank having a halftone film on the glass substrate 10 and a light shielding film on the halftone film, or a so-called binary type in which a light shielding film is formed on the glass substrate 10 for mask blank. It may be a mask blank. Examples of the structure of the light shielding film in this case include a two-layer laminated structure of a light shielding layer and a front surface antireflection layer from the substrate side, and a three-layer laminated structure in which a back surface antireflection layer is added between the substrate and the light shielding layer. It is done. As a material used for the light shielding film, a material mainly composed of chromium is first mentioned, and this is appropriately used as a main component so as to satisfy the characteristics required for the back surface antireflection layer, the light shielding layer, and the surface antireflection layer. It is preferable to use materials oxidized, nitrided, carbonized, etc., respectively. In addition, examples of materials applicable to the light-shielding film other than chromium include transition metal silicides composed of silicon and transition metals such as molybdenum, tungsten, and zirconium. It is preferable to use a material oxidized, nitrided, carbonized or the like. In addition, a light shielding film having a two-layer laminated structure or a three-layer laminated structure may be formed using a material mainly composed of tantalum and appropriately oxidized, nitrided, carbonized, or the like. Note that a resist film may be formed on the light-shielding film of these halftone phase shift mask blank and binary mask blank.

  The present invention relates to a transfer mask used as a transfer mask for an ultrafine pattern in the manufacture of a VLSI, a mask blank used as a material for the transfer mask, and a mask blank used as a material for the mask blank. It can be used for the production of glass substrates.

DESCRIPTION OF SYMBOLS 10 ... Glass substrate 11 for mask blanks, 12 ... Main surface 13, 14, 15, 16 ... End surface 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b ... Chamfering surface 20 ..Glass substrate defect inspection device 21... Laser device 22... XYZ stage 23... CCD camera 27.

Claims (8)

The shape of a glass substrate for a mask blank, which is obtained by grinding plate glass cut out from a glass ingot and having two main surfaces , four end surfaces , and a chamfered surface formed at a corner where the main surface and the end surface intersect A primary shape processing step for processing into
A mirror polishing step of mirror polishing at least one end surface of the glass substrate;
An inspection light having a wavelength of 200 nm or less is introduced into the glass substrate from the one end surface of the glass substrate that has been mirror-polished, and the presence or absence of fluorescence generated from an internal defect by the inspection light is determined from one side of the main surface. A defect inspection process for inspecting and selecting a glass substrate from which fluorescence is not detected;
With increasing the chamfered surface of the selected glass substrate, the two major surfaces and four end surfaces of the grinding and polishing line Ukoto of the selected glass substrate, in shade of the chamfered surface in the defect inspection step And a secondary shape processing step for removing a region near the main surface where the intensity of the inspection light was weak ,
Wherein both main surfaces between the direction of the width of the region reaching the inspection light intensity required for fluorescence is generated from the internal defects of the glass substrate in the defect inspection process, both the glass substrate after the second shaping step much larger than the thickness between the main surface,
The chamfered surface formed in the primary shape processing step, the chamfered surface located on the inspection light introduction side and the chamfered surface facing the chamfered surface across the main surface are in both main surface directions. The method of manufacturing a glass substrate for a mask blank, characterized in that the dimensions are the same .   The glass substrate for a mask blank according to claim 1, wherein the glass substrate after the secondary shape processing step has a chamfered surface formed at a corner where two main surfaces and the four end surfaces intersect. Manufacturing method. The glass substrate to be inspected in the defect inspection step has a chamfered surface formed at a corner where two main surfaces and the four end surfaces intersect, and a chamfered surface on one main surface side and an end surface intersect. and the corner portion, the width at the both main surfaces between the direction between the corners and the chamfered surface and the end surface intersects the other major surface side, between both main surfaces of the glass substrate after the second shaping step The method for producing a glass substrate for a mask blank according to claim 1, wherein the method is larger than the thickness. The method for producing a glass substrate for a mask blank according to any one of claims 1 to 3, wherein the inspection light used in the defect inspection step is laser light. The said glass substrate consists of synthetic quartz, The manufacturing method of the glass substrate for mask blanks in any one of Claim 1 to 4 characterized by the above-mentioned. A mask comprising a step of forming a thin film for pattern formation on a main surface of a glass substrate for a mask blank manufactured by the method for manufacturing a glass substrate for a mask blank according to any one of claims 1 to 5. Blank manufacturing method. A method for producing an exposure mask, comprising a step of forming a transfer pattern for exposure on the thin film for pattern formation of the mask blank produced by the method for producing a mask blank according to claim 6. An exposure mask manufactured by the method for manufacturing an exposure mask according to claim 7 is placed on a mask stage of an exposure apparatus, and pattern transfer using ArF exposure light is applied to a resist film which is a transfer object. The pattern transfer method characterized by performing.

Images