KR20100035598A - Method for manufacturing substrate for mask blank and substrate thereby - Google Patents

Abstract

PURPOSE: A manufacturing method of a substrate for a blank mask and a blank mask manufactured using the same are provided to obtain a flat photomask by producing a photo mask from a substrate for a mask blank in shape of major surface. CONSTITUTION: A substrate(4) is held on a carrier(1). The substrate is placed between an upper plate(2) and a lower plate(3). The upper plate and the lower plate rotate with respect to a rotation axis which is perpendicular to a polishing surface. The revolving axis of the substrate is made eccentric with respect to a rotary shaft of the lower plate. A part of a substrate is arranged on the rotary shaft of the bottom plate. The substrate rotates by rotating the carrier.

Description

Method of manufacturing substrate for mask blank and substrate for mask blank {METHOD FOR MANUFACTURING SUBSTRATE FOR MASK BLANK AND SUBSTRATE THEREBY}

The present invention relates to a method for producing a mask blank substrate and a mask blank substrate.

In recent years, in electronic devices such as semiconductor devices and liquid crystal displays, further miniaturization is required due to the rapid development of IT technology. One technique for supporting such a microfabrication technique is a photolithography technique using a photomask. In this photolithography technique, a fine pattern is transferred to and formed on a silicon wafer by exposing the electromagnetic wave or light wave of the light source for exposure to a silicon wafer with a resist film through a photomask. This photomask is usually produced by forming a pattern of a disc using a photolithography technique on a mask blank on which a light shielding film is formed on a transparent substrate. Due to the recent demand for miniaturization of patterns, high flatness is required for a mask blank substrate.

In recent years, the demand for large-sized mask blank substrates used in the manufacture of flat panel displays such as liquid crystal displays, organic electroluminescent displays, plasma panel displays, and the like is increasing. Therefore, various manufacturing methods of the large sized mask blank substrate are proposed (for example, refer Unexamined-Japanese-Patent No. 2007-54944).

However, especially in the large mask blank substrate, it was difficult to efficiently manufacture the mask blank substrate which has high flatness.

Since the mask blank substrate is required to have high flatness and no defects such as scratches and foreign matter, a polishing (polishing) step is usually provided in the manufacturing process of the mask blank substrate.

FIG. 5: is a figure for demonstrating the outline of the conventional grinding | polishing process of the large sized mask blank board | substrate, FIG. 5 (a) has shown the top view, and FIG. 5 (b) has shown the side view. 6 is a schematic perspective view of the substrate 4. In the drawings, reference numeral 1 denotes a carrier, 2 an upper plate, 3 a lower plate, 4 a substrate of a mask blank substrate, 5 a polishing surface of an upper plate, 6 a polishing of a lower plate. The surface O1 represents the rotation axis of the upper plate, O2 represents the rotation axis of the lower plate, O3 represents the rotation axis of the substrate, 7 represents the main surface of the substrate 4, and 8 represents the cross section of the substrate 4, respectively.

5 and 6, first, the end surface of the substrate 4 is held by the carrier 1, and the polishing surface 5 and the lower surface plate of the upper surface plate 2 provided with the substrate 4 facing up and down. It is located between the grinding | polishing surfaces 6 of 3). Then, the substrate 4 is sandwiched by bringing both major surfaces 7 of the substrate 4 into contact with the polishing surface 5 of the upper plate 2 and the polishing surface 6 of the lower plate 3. Thereafter, the upper and lower plates 2 and 3 are rotated with respect to the rotation axes O1 and O2 perpendicular to the polishing surfaces 5 and 6, respectively. At the same time, the rotation axis 03 of the substrate 4 is eccentrically parallel to the rotation axis O2 of the lower platen so that a part of the substrate 4 is positioned on the rotation axis O2 of the lower platen. In this state, the substrate 4 is rotated by rotating the carrier 1. As a result, the polishing surfaces 5 and 6 of the upper and lower plates and the two main surfaces 7 of the substrate 4 are relatively moved while contacting each other. As a result, both major surfaces 7 of the substrate 4 are polished.

However, the polishing ability of the surface plate is not uniform in all regions of the surface of the surface plate, and depends on the pressure and the main speed of the portion where the surface of the surface plate comes into contact with the polished object. Since the circumferential speed of the surface plate is proportional to the distance (radius) from the rotational axis, since the circumferential speed varies greatly around the rotational axis and around the outer circumference of the surface plate, a great difference occurs in the polishing ability near the rotational axis and around the outer circumference of the surface plate. For example, since the substrate 4 is rotating, the rotational trajectory of the substrate 4 at the portion passing through the upper and lower rotary shafts O1 and O2 in the upper and lower plates becomes the circumference A. In FIG. On this circumference A, near the rotary shafts O1 and O2 of the upper and lower surface plates 2 and 3, which pass through the outer peripheral region of the upper and lower surface plates 2 and 3, which have relatively high polishing ability, but have the lowest smoke capacity. Since the area | region also passes, the total amount of grinding | polishing on the circumference A of the board | substrate 4 will become small. On the other hand, in the center of the substrate 4 and on the rotation axis (C) at the point (B) corresponding to the rotation axis O3 or the center surface of the cross section of the substrate 4, the upper and lower surface plates 2 having a relatively high polishing ability , 3) the total amount of polishing on the point (B) or the circumference (C) is larger than that on the circumference (A).

As a result, polishing unevenness (difference in polishing amount) occurred in both main surfaces of the mask blank substrate manufactured through the conventional polishing process of the large mask blank substrate.

It is a figure which shows an example of the cross section of the mask blank substrate manufactured through the grinding | polishing process of the conventional large mask blank substrate. (A), (B), (C) in FIG. 7 has shown the same part as (A), (B), (C) in FIG. 5 (a). (B) corresponding to the central portion of the main surface of the substrate 4 and (C) corresponding to the central portion of the cross section of the substrate 4 are concave in shape because of the large amount of polishing, and are on the upper and lower rotary shafts O1 and O2. Corresponding to (A) becomes convex because the overall polishing amount is small.

As described above, in the mask blank substrate manufactured through the conventional polishing process for the large mask blank substrate, two convex shapes are formed on or near the rotation axis of the surface plate with a small amount of polishing, resulting in high flatness. The mask blank substrate could not be realized.

In the one-side polishing field where only one surface of the substrate is polished, the polishing surface of the rotating platen is convex, and a spring structure is installed between the plate holding the substrate and the shaft rotating the plate to incline the polishing and the like. A technique for controlling the amount of polishing by carrying out has been proposed (see, for example, Japanese Patent Laid-Open No. 2005-262441).

However, in the field of double-side polishing, since both major surfaces of the substrate are polished at the same time, plates in the field of single polishing cannot be used. Therefore, in order to rotate the substrate, it is common to adopt a form in which the end surface of the substrate is rotated by a carrier. to be. Therefore, in the field of double-side polishing, in order to freely move the position of the substrate on the polishing surface of the surface plate, a drive system such as a carrier holding the substrate and an internal gear for rotating the carrier is moved, or an upper and lower surface plate and the drive system instead of the substrate side. It is necessary to employ a very large way of moving the. However, adopting such a massive method is not realistic. In addition, even if a method of moving the upper and lower plates and the drive system, etc., is employed, it is technically very difficult to level the internal gear and the surface plate, and high precision polishing cannot be performed. Therefore, it is almost impossible to transfer the technology in the one-side polishing field to the double-side polishing field.

SUMMARY OF THE INVENTION In view of such circumstances, an object of the present invention is to provide a method for efficiently manufacturing a mask blank substrate having a high flatness in a large mask blank substrate, and to provide a mask blank substrate having excellent pattern transfer accuracy.

In order to achieve the above object of the present invention, the method for producing a mask blank substrate according to the present invention is a method for producing a mask blank substrate for manufacturing a mask blank substrate through a polishing step of polishing both main surfaces of the substrate. The polishing process includes the steps of: holding the substrate with a carrier, pinching the substrate between the upper and lower surfaces of the upper and lower surfaces disposed opposite to each other, and the upper and lower surfaces perpendicular to the polishing surface. Respectively rotating about an axis of rotation, positioning a portion of the substrate on or near the axis of rotation of the lower plate by eccentrically rotating the rotation axis of the substrate with respect to the axis of rotation of the lower plate, and rotating the carrier And rotating the at least one surface of the upper surface plate to a predetermined radius of curvature. Which comprises part of a spherical surface, it characterized in that the estimated half rotation axis inclined at a predetermined angle relative to the axis of rotation hajeong half.

Further, the polishing surface of the lower plate may be made of a part of a spherical surface having a predetermined radius of curvature.

In addition, the method for manufacturing a mask blank substrate according to the present invention is a method for manufacturing a mask blank substrate for manufacturing a mask blank substrate through a polishing step of polishing both main surfaces of the substrate, wherein the polishing step is used as a carrier. Holding the substrate, and pinching the substrate between the upper and lower surfaces of the upper and lower surfaces disposed opposite to each other; rotating the upper and lower surfaces about an axis of rotation perpendicular to the polishing surface, respectively, Positioning a portion of the substrate on or near the rotation axis of the upper plate by rotating an axis of rotation of the upper plate parallel to the rotation axis of the upper plate, and rotating the carrier by rotating the carrier, at least the lowering The half polished surface consists of a part of a spherical surface having a predetermined radius of curvature, It characterized in that the half of the rotational axis inclined at a predetermined angle relative to the axis of rotation half the assumed.

In addition, the polishing surface of the upper surface plate may be made of a part of a spherical surface having a predetermined radius of curvature.

Further, the mask blank substrate may be a mask blank substrate of a flat panel display.

Here, the board | substrate is a substantially rectangular shape which consists of a pair of long side and a pair of short side, and a short side may be 400 mm or more.

In addition, the polishing step may be repeated several times.

In addition, the mask blank substrate of the present invention has a substantially rectangular shape consisting of a pair of long sides and a pair of short sides, and has a short side of 400 mm or more, with at least one main surface of the mask blank substrate centered on a central portion of the main surface. It is one convex shape and the flatness of a main surface is 20 micrometers or less.

The manufacturing method of the mask blank substrate of this invention has the advantage that the mask blank substrate which has high flatness can be manufactured efficiently. The mask blank substrate of this invention becomes convex shape centering on the center part of the main surface of a mask blank substrate. When a photomask is produced from such a mask surface substrate having a main surface shape, when the photomask is chucked to the mask stage of the exposure apparatus by vacuum adsorption or the like, the flatness is deformed in a direction that improves flatness than before the chuck. There is also an advantage that a photomask having a high flatness can be obtained at the time of chucking.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS It is a flowchart for demonstrating the whole manufacturing method of the mask blank substrate of this invention. This manufacturing method is subjected to lapping process (S101), polishing process (S102), washing process (S103), and evaluation process (S104). The lapping step (S101) is performed for the purpose of uniformizing the process warping layer of the substrate and adjusting the plate thickness dimension of the substrate to a predetermined plate thickness dimension to improve flatness. Lapping process S101 is performed using a lapping apparatus etc., for example. In addition, the lapping process may be performed several times, or the lapping process of each content may be implemented. For example, you may perform the rough lapping process using a grain with a large particle size first, and then perform the sharp lapping process using the grain with a small particle size.

The polishing step S102 is carried out for the purpose of further improving the smoothness of the main surface of the substrate while maintaining and improving the flatness obtained by the lapping step S101, and for the purpose of removing particles adhering to the main surface of the substrate. .

Fig. 2 is a view for explaining the outline of the first embodiment of the polishing step in the method for manufacturing a mask blank substrate of the present invention, where (a) is a top view and (b) is a side view. In the figure, the same code | symbol is shown with the part same as FIG.

In the first embodiment, first, the substrate 4, which is the original plate of the mask blank substrate, is held by the carrier 1, and the polishing surface 5 of the top plate 2 provided with the substrate 4 facing up and down. It is located between the polishing surfaces 6 of the lower plate 3. Then, the upper surface polished surface 5 and the lower surface polished surface 6 are brought into contact with each other so as to be in contact with each other. Thereafter, the upper and lower plates 2 and 3 are rotated with respect to the rotation axes O1 and O2 perpendicular to the polishing surfaces 5 and 6, respectively. At the same time, the rotation axis O3 of the substrate 4 is eccentrically parallel to the rotation axis O2 of the lower platen, so that a portion of the substrate 4 is positioned on or near the rotation axis O2 of the lower platen. In this state, the substrate 4 is rotated by rotating the carrier 1. In this case, the polishing surfaces 5 and 6 are made up of a part of a spherical surface having a predetermined radius of curvature, and the rotation axis O1 of the upper platen is at a predetermined angle θ1 with respect to the rotation axis O2 of the lower platen 3. It is inclined.

That is, in the first embodiment, the polishing of the substrate 4 is carried out using the upper and lower plates 2 and 3, wherein the shape of the polishing surfaces 5 and 6 is a part of a spherical surface having a predetermined radius of curvature. The rotation axis O1 of the upper platen is inclined by a predetermined angle θ1 with respect to the rotation axis O2 of the lower platen.

As shown in Fig. 2 (b), the upper surface polishing surface 5 made of a part of a spherical surface having a predetermined radius of curvature by inclining the rotation axis O1 of the upper surface plate by a predetermined angle θ1 with respect to the rotation axis O2 of the lower surface plate. The region in the vicinity of the rotation axis 01 of the region does not come into contact with the substrate 4 or is in a state of being in contact with it slightly. On the other hand, by inclining the rotating shaft O1 of the upper surface plate, the outer peripheral portion region of the upper surface polishing surface 5 is in a state of being in strong contact with the substrate 4.

The circumference A of FIG. 2 (a) shows the rotation trajectory of the substrate 4 at the portion passing through the rotation axis O 2 of the lower plate. The area near the rotation axis O1 of the upper surface polishing surface 5 on the circumference A is not in contact with the substrate 4 or the contact is made small so that the area near the rotation axis O1 of the upper surface plate with low polishing ability. The amount of polishing due to this decreases. However, since the outer peripheral portion region of the upper surface polishing surface 5 having relatively high polishing ability is in strong contact with the substrate 4, the amount of polishing by the outer peripheral portion region of the upper surface polishing surface 5 greatly increases.

In addition, the contact surface of the upper surface polishing surface 5 and the substrate 4 is formed even when the rotation axis O1 of the upper surface is inclined by making the shape of the upper surface polishing surface 5 part of a spherical surface having a predetermined curvature radius. It can be widened and the board | substrate 4 by the upper surface polishing surface 5 can be polished efficiently. Moreover, the contact area becomes wider, the contact strength of the upper surface polishing surface 5 and the board | substrate 4 can be made suitable, and polishing can be performed with high precision.

As a result, the overall polishing amount on the circumference A is increased than the polishing amount in the polishing step in the conventional method for manufacturing a mask blank substrate. As a result, the two convex shape problems occurring in the portions corresponding to the vicinity of the upper and lower rotating shafts O1 and O2 of the substrate 4 formed in the polishing process in the conventional method of manufacturing a mask blank substrate are eliminated. Will be.

In addition, (B) of FIG. 2 (a) is a center part of the board | substrate 4, the part corresponding to the rotation axis O3, and the circumference | surroundings C have shown the rotation trace of the center part of the cross section of the board | substrate 4. As shown to FIG. On the periphery of the point (B) or the outer peripheral side of the upper platen polishing surface 5 of the circumference C, the polishing ability is inclined by a predetermined angle (θ1) with respect to the rotational axis O1 of the upper platen with respect to the rotation axis O2 of the lower platen. Since it strongly contacts the outer peripheral portion region of the high top plate polishing surface 5, the overall polishing amount on the point (B) and the circumference (C) is the polishing amount in the polishing step in the conventional method for manufacturing a mask blank substrate. Will increase.

In other words, the amount of polishing is increased in all regions of the main surface of the substrate, such as the circumference A, the point B, and the circumference C. Thereby, the time required for a polishing process can be shortened rather than the polishing process in the conventional manufacturing method of the mask blank substrate, and a mask blank substrate can be manufactured efficiently.

In the first embodiment, the lower surface polishing surface 6 is made up of a part of a spherical surface having a predetermined radius of curvature.

In double-sided polishing, polishing on the upper surface polishing surface 5 and the lower surface polishing surface 6 is performed simultaneously, so that the polishing situation by the upper surface polishing surface 5 is the polishing situation on the lower surface polishing surface 6. Affects. For example, when polishing is performed in the outer peripheral portion region of the upper polishing surface 5 by tilting the upper plate 2, the outer peripheral portion region of the upper polishing surface 5 and the substrate 4 are strongly in contact with each other. The board | substrate 4 which hold | maintained only the cross section by 1) is pressed by the outer peripheral part of the upper surface polishing surface 5, and inclines to the outer peripheral part side of the lower surface plate 3 only slightly. As a result, the board | substrate 4 and the lower surface polishing surface 6 contact too strongly, and it grind | polishs more than necessary, and the flatness of the main surface of the board | substrate of the lower surface side will fall.

In the first embodiment, the lower surface polishing surface 6 is part of a spherical surface having a predetermined radius of curvature. As a result, a slight gap is generated between the lower platen polishing surface 6 and the substrate 4 as it moves toward the outer circumferential direction of the lower platen 3, or the lower platen polishing surface 6 contacts the substrate 4. Strength is weakened. A slight gap between the lower platen polishing surface 6 and the substrate 4 or the slight decrease of the contact strength between the lower platen polishing surface 6 and the substrate 4 causes the slight inclination to the substrate 4. Even if it exists, it is preferable because the lower surface polishing surface 5 and the board | substrate 4 can prevent strong contact, and contact strength can be appropriately maintained. In addition, the substrate 4 is slightly inclined to the outer peripheral side of the lower plate 3 so that the region near the rotation axis O2 of the lower plate and the substrate 4 do not come into contact or are slightly in contact with each other. ) It can suppress the influence of polishing nonuniformity caused by passing through the vicinity. As a result, since the lower surface polishing surface 6 can perform grinding | polishing of the lower surface side main surface of the board | substrate 4 appropriately, the flatness of the board | substrate 4 can be made favorable and it is preferable.

Thus, in the double-sided polishing field, the polishing situation by the top plate also affects the polishing situation of the bottom plate. Since the problem to be solved differs from the two-side polishing technique of simultaneously polishing the surface, it is very difficult to dedicate the one-side polishing technique to the two-side polishing.

The lower limit of the inclination angle θ1 of the upper surface rotation axis O1 is usually 1.0 × 10 ⁻⁵ (deg) or more, preferably 3.0 × 10 ⁻⁴ (deg) or more. The upper limit is usually 1.0 × 10 ⁻³ (deg) or less, preferably 5.0 × 10 ⁻⁴ (deg) or less. By setting it as this range, grinding | polishing can be performed efficiently in the outer peripheral part area | region of the upper surface polishing surface 5, effectively suppressing the grinding | polishing influence in the area | region where the polishing ability near the upper surface rotating shaft O1 is low. Thereby, the mask blank substrate which has high flatness can be manufactured efficiently.

The upper and lower polished surfaces 5 and 6 have a predetermined radius of curvature, and the lower limit of the radius of curvature is usually 1 km or more, preferably 10 km or more. The upper limit is usually 100 km or less, preferably 50 km or less. By setting it as this range, the contact area of the grinding surfaces 5 and 6 of the upper and lower surface plate and the board | substrate 4 can be ensured widely, contact strength can be appropriately adjusted, and efficient grinding | polishing can be performed. In addition, the radius of curvature of the upper surface polishing surface 5 and the lower surface polishing surface 6 does not need to be the same, and may differ, respectively.

Further, the polishing surfaces 5 and 6 of the upper and lower platen may be formed integrally with the upper and lower platen 2 and 3, or may be configured by applying an abrasive cloth or the like to the upper and lower platen 2 and 3.

The substrate 4 is not particularly limited as long as it is a substrate that can be polished and transmits light as an original of the mask blank substrate, but a glass substrate is usually used. As the material of the glass substrate, quartz glass, alkali free glass, borosilicate glass, aluminosilicate glass, soda lime glass and the like are usually used. The shape of the board | substrate 4 may be any shape, such as rectangular shape, a square shape, a circular shape, a disk shape, and a block shape, as long as it can be pinched between the grinding surfaces 5 and 6 of the upper and lower surface plates. Is used. Although the size of the board | substrate 4 changes with the use of the mask blank board | substrate, if it is a board | substrate of substantially rectangular shape, the length of a short side is 100 mm or more and 1,500 mm or less normally. Moreover, the thickness of the board | substrate 4 is 0.5 mm or more and 15 mm or less normally.

The present invention effectively eliminates the polishing unevenness caused by the difference in polishing ability depending on the circumferential speed in the region near the rotary shafts O1 and O2 of the upper and lower plates and the outer peripheral portion of the polishing surfaces 5 and 6 of the upper and lower plates. It can be suppressed. Therefore, in the present invention, a large mask blank substrate is used in which a polishing process is performed using both the regions near the rotation shafts O1 and O2 of the upper and lower plates and the outer peripheral region of the polishing surfaces 5 and 6 of the upper and lower plates. It is suitable for manufacture of the mask blank substrate of a flat panel display. Moreover, it is suitable also for manufacture of the mask blank substrate which uses the board | substrate whose length of a short side is 400 mm or more as a substantially rectangular shape board which consists of a pair of long side and a pair of short side generally classified as a large mask blank substrate.

In addition, in the first embodiment, the lower surface polishing surface 6 has been described using an embodiment in which a part of a spherical surface having a predetermined radius of curvature is used. However, the present invention has the upper and lower surface polishing surfaces 5 and 6 both. It does not need to consist of a part of the spherical surface which has a predetermined radius of curvature, and in the first embodiment, the polishing surface 6 of the lower half may be formed in a plane.

Fig. 3 is a view for explaining the outline of a second embodiment of the polishing step in the method for manufacturing a mask blank substrate of the present invention, where (a) is a top view and (b) is a side view. In the drawings, the portions denoted by the same reference numerals as those in FIG. 2 indicate the same elements, and thus redundant description is omitted.

In the second embodiment, first, the substrate 4 is held by the carrier 1, and the polishing surface 5 and the polishing surface of the lower surface plate 3 of the upper surface plate 2 provided with the substrate 4 facing up and down. Position it between (6). The upper surface polished surface 5 and the lower surface polished surface 6 are held in contact with both main surfaces of the substrate 4. After that, the upper plate 2 and the lower plate 3 are rotated with respect to the rotation axes O1 and 02 perpendicular to the polishing surfaces 5 and 6, respectively. At the same time, the rotation axis O3 of the substrate 4 is eccentrically parallel to the rotation axis O1 of the upper surface plate, so that a portion of the substrate 4 is positioned on or near the rotation axis O1 of the upper surface plate. In this state, the substrate 4 is rotated by rotating the carrier 1. In this case, the polishing surfaces 5 and 6 are made up of a part of a spherical surface having a predetermined radius of curvature, and the rotation axis O2 of the lower platen is inclined at a predetermined angle θ2 with respect to the rotation axis O1 of the upper platen.

In other words, the second embodiment reverses the configuration of the upper plate 2 and the lower plate 3 of the first embodiment. Also in the structure of such a 2nd Example, the effect | action similar to a 1st Example, and an effect can be exhibited.

In the second embodiment, the lower limit of the inclination angle θ2 of the rotation axis O2 of the lower platen is usually 1.0 × 10 ⁻⁵ (deg) or more, preferably 3.0 × 10 ⁻⁴ (deg) or more. The upper limit is usually 1.0 × 10 ⁻³ (deg) or less, preferably 5.0 × 10 ⁻⁴ (deg) or less. By setting it as this range, grinding | polishing can be efficiently performed in the outer peripheral part area | region of the lower surface polishing surface 6, effectively suppressing the grinding | polishing influence in the area | region where the polishing ability near the rotating shaft O2 of a lower surface plate is low. Thereby, the mask blank substrate which has high flatness can be manufactured efficiently.

In the second embodiment, the embodiment has been described using an embodiment in which the upper surface polishing surface 5 is part of a spherical surface having a predetermined radius of curvature. However, in the present invention, both the polishing surfaces 5 and 6 have a predetermined curvature. It is not necessary to consist of a part of spherical surface which has a radius, and the grinding | polishing surface 5 of a top plate may be made into a plane in 2nd Example.

The polishing step S102 may be carried out several times or may be carried out with polishing steps having different contents. For example, a first polishing step may be performed first using a polishing cloth made of a hard polisher as the polishing surface, and then a second polishing step may be performed using the polishing cloth made of the soft polisher as the polishing surface. Thus, the mask blank substrate which has higher flatness can be manufactured by repeating grinding | polishing process S102 several times, and it is preferable.

The cleaning step S103 is performed for the purpose of removing the abrasive grains adhered to the substrate by the polishing step S102. The cleaning step (S103) is performed by, for example, sequentially immersing the substrate in alkali (NaOH) and sulfuric acid and applying ultrasonic waves.

Evaluation process S104 is performed for the purpose of evaluating whether the board | substrate which passed through cleaning process S103 can be used as a board | substrate for mask blanks. Evaluation process S104 confirms the measurement of the flatness or smoothness of a board | substrate, the presence of the crack in the main surface of a board | substrate, etc., for example, and removes the thing which does not satisfy | fill the standard as a mask blank substrate.

4 is a cross-sectional view of an example of a mask blank substrate manufactured through a first embodiment of a polishing step in the method of manufacturing a mask blank substrate of the present invention. (A), (B), (C) in FIG. 4 has shown the same part as (A), (B), (C) in FIG. In the first embodiment, the polishing surfaces 5 and 6 of the upper and lower plates are made up of a part of a spherical surface having a predetermined radius of curvature, and the rotation axis O1 of the upper platen is at a predetermined angle θ1 with respect to the rotation axis O2 of the lower platen. The inclined configuration can effectively suppress the polishing nonuniformity caused by the difference in the polishing ability between the region near the rotary shafts O1 and O2 of the upper and lower plates and the outer peripheral region of the polishing surfaces 5 and 6 of the upper and lower plates. Both main surfaces of the substrate 4 can be polished. In the first embodiment, the polishing amount is strongly in contact with the outer circumferential side region of the upper and lower surface polishing surfaces 5 and 6 having high polishing ability in the order of (B) <(A) <(C). It increases in order of (A) <(C). As a result, the mask blank substrate has a convex shape whose main surface is centered on the central portion B of the main surface.

The material of the mask blank substrate is the same as that of the substrate 4. The shape, size, and thickness of the mask blank substrate are generally the same as the shape, size, and thickness of the substrate 4. As a shape of the mask blank substrate manufactured by this invention, the short side is 400 mm or more in the substantially rectangular shape which consists of a pair of long side and a pair of short side, for example.

The flatness of the main surface of the mask blank substrate is usually more than 0 µm and 20 µm or less, preferably more than 0 µm and 10 µm or less. By setting it as this range, the attachment (chuck) property to the exposure apparatus etc. after photomask manufacture is excellent, and pattern position precision and pattern transfer precision improve.

The flatness of the above-mentioned mask blank substrate can be easily manufactured by implementing the manufacturing method of the mask blank substrate of this invention. In the present invention, the flatness means the difference between the maximum height and the minimum height of the surface shape in the main surface from the reference surface arbitrarily installed on each main surface of each main surface of the mask blank substrate (from the measurement surface to the least square method). The difference between the maximum and minimum values of the measurement plane relative to the calculated absolute absolute plane. In addition, the method of measuring flatness is not particularly limited, but for example, a tactile contact flatness measuring method or a non-contact flatness measuring method using light interference, etc. may be used. It is preferable to use the non-contact flatness measuring method from the point of non-destructive test.

The mask blank substrate obtained by implementing the manufacturing method of the mask blank substrate of this invention becomes a convex shape centering on the center part of the main surface of the mask blank substrate. When a photomask is created from such a mask surface substrate having a main surface shape, the photomask is deformed in a direction of improving flatness than before chucking when the photomask is chucked by vacuum suction or the like on the mask stage of the exposure apparatus. Has a high flatness. When the substrate main surfaces on the opposite side surfaces of the substrate are respectively adsorbed to the mask stage by vacuum adsorption or the like, the main surface of the substrate is attracted from both side surfaces of the substrate and the center portion of the main surface of the substrate can be deformed in a concave direction. . At this time, if the main surface of the substrate is convex with the center as the center, even if the central portion of the main surface of the substrate is concave, the chuck transition convex is closer to the flat surface. For this reason, it is preferable that the main surface of the substrate is polished so as to have a convex shape centered on the center portion, and the method of manufacturing the mask blank substrate of the present invention is optimal.

In addition, the manufacturing method of the mask blank substrate of this invention and the mask blank substrate are not limited only to the above-mentioned example, Of course, various changes can be added within the range which does not deviate from the summary of this invention. For example, another process may be provided between the lapping process (S101) and the polishing process (S102), such as a shape processing process for grinding the cross section of the substrate to adjust the external dimensions.

BRIEF DESCRIPTION OF THE DRAWINGS It is a flowchart for demonstrating the whole manufacturing method of the mask blank substrate of this invention.

Fig. 2 is a view for explaining the outline of the polishing process of the mask blank substrate according to the first embodiment of the present invention, where (a) is a top view and (b) is a side view.

Fig. 3 is a view for explaining the outline of the polishing process of the mask blank substrate according to the second embodiment of the present invention, where (a) is a top view and (b) is a side view.

4 is a cross-sectional view of an example of a mask blank substrate manufactured through a polishing step of the mask blank substrate of the present invention.

Fig. 5 is a view for explaining an outline of a conventional polishing process for a large-sized mask blank substrate, wherein (a) is a top view and (b) is a side view.

6 is a schematic perspective view of a substrate.

7 is a cross-sectional view of an example of a mask blank substrate manufactured through a conventional polishing process for a large mask blank substrate.

Claims (12)

A method of manufacturing a mask blank substrate, which manufactures a mask blank substrate through a polishing step of polishing both major surfaces of the substrate, The polishing process, Holding the substrate with a carrier, Sandwiching the substrate between the upper and lower polished surfaces of the upper and lower surfaces disposed opposite to each other; Rotating the upper and lower plates about a rotation axis perpendicular to the polishing surface, respectively; Eccentrically rotating the rotation axis of the substrate with respect to the rotation axis of the lower plate to position a portion of the substrate on or near the rotation axis of the lower plate; and Rotating the substrate by rotating the carrier, At least a polishing surface of the upper surface plate is made of a part of a spherical surface having a predetermined radius of curvature, and the rotation axis of the upper surface plate is inclined at a predetermined angle with respect to the rotation axis of the lower surface plate. The method of claim 1, A method for manufacturing a mask blank substrate, characterized in that the polishing surface of the lower platen is made of a part of a spherical surface having a predetermined radius of curvature. A method of manufacturing a mask blank substrate, which manufactures a mask blank substrate through a polishing step of polishing both major surfaces of the substrate, The polishing process, Holding the substrate with a carrier, Sandwiching the substrate between the upper and lower polished surfaces of the upper and lower surfaces disposed opposite to each other; Rotating the upper and lower plates about a rotation axis perpendicular to the polishing surface, respectively; Eccentrically rotating the rotation axis of the substrate with respect to the rotation axis of the upper plate to position a portion of the substrate on or near the rotation axis of the upper plate; and Rotating the substrate by rotating the carrier, At least a polishing surface of the lower platen is made of a part of a spherical surface having a predetermined radius of curvature, and the rotation axis of the lower platen is inclined at a predetermined angle with respect to the rotation axis of the upper platen. The method of claim 3, wherein A method for manufacturing a mask blank substrate, characterized in that the polishing surface of the upper surface plate is made of a part of a spherical surface having a predetermined radius of curvature. The method according to any one of claims 1 to 4, The said predetermined angle is 1.0 * 10 <^-5> (deg) or more and 1.0 * 10 <^-3> (deg) or less, The manufacturing method of the mask blank substrate characterized by the above-mentioned. The method according to any one of claims 1 to 4, Said predetermined angle is 3.0 * 10 <^-4> (deg) or more and 5.0 * 10 <^-4> (deg) or less, The manufacturing method of the mask blank substrate characterized by the above-mentioned. The method according to any one of claims 1 to 4, The predetermined radius of curvature is a manufacturing method of the mask blank substrate, characterized in that 1km or more, 100km or less. The method according to any one of claims 1 to 4, The predetermined radius of curvature is a manufacturing method of the mask blank substrate, characterized in that 10km or more, 50km or less. The method according to any one of claims 1 to 4, And said mask blank substrate is a mask blank substrate of a flat panel display. The method according to any one of claims 1 to 4, And said substrate is a substantially rectangular shape consisting of a pair of long sides and a pair of short sides, and the short side thereof being 400 mm or more. The method according to any one of claims 1 to 4, A method of manufacturing a mask blank substrate, characterized in that the polishing process is repeated several times. A mask blank substrate having a substantially rectangular shape consisting of a pair of long sides and a pair of short sides and having a short side of 400 mm or more, A mask blank substrate having at least one major surface of the mask blank substrate having a convex shape centered on a central portion of the main surface and having a flatness of 20 µm or less.

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