JP2006297524A - Guide ring for polishing rectangular substrate, polishing head, and method for polishing rectangular substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a guide ring capable of finishing a rectangular substrate to a rectangular substrate easily and surely having high flatness when polishing the rectangular substrate such as a photomask substrate. <P>SOLUTION: When polishing the rectangular substrate 6, while pressing the rectangular substrate 6 against polishing cloth, this guide ring 1 prevents the excessive polishing of the surrounding part of the substrate 6 by pressing the polishing cloth around the substrate 6. In the guide ring 1, a storing part 2 for storing the substrate 6 is provided, and a cut-out part 4 communicated with the outside of the guide ring 1 is formed in a part around the storing part 2 on a surface 3 in contact with the polishing cloth. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a guide ring used for preventing excessive polishing of a peripheral portion of a substrate when a square substrate such as a photomask substrate or a liquid crystal substrate is polished.

  In recent years, with the high integration of integrated circuits such as DRAM, the demand for miniaturization of pattern rules for circuit design has been increasing year by year. Along with this, the wavelength used for the light source used in the photolithography process has shifted to the direction of using i-line, KrF excimer laser, ArF excimer laser, and shorter wavelengths.

  While shortening the exposure wavelength improves the critical resolution, the depth of focus becomes shallower, so it has become an important issue to remove other factors that make the depth of focus shallower. If the flatness of the substrate in the photomask used in the lithography process is low, the distance between the mask pattern and the lens varies depending on the position of the mask pattern, resulting in a shallow depth of focus. Therefore, higher flatness has been required for a photomask substrate as a photomask material. For example, in a 152 mm × 152 mm photomask, the flatness is 0.5 μm or less, and further 0.3 μm. The following are becoming desirable:

As the photomask substrate, a synthetic quartz glass substrate is mainly used. When manufacturing such a photomask substrate, normally, after forming a glass ingot as a raw material, it is melted by heat and formed into a square shape, which is sliced into a substrate shape. A flat photomask substrate can be obtained by performing polishing several times in order to increase the accuracy from rough polishing to precise polishing.
When polishing a substrate in manufacturing such a photomask substrate, there is a method of polishing a plurality of substrates with a double-side polishing apparatus. Polishing both surfaces of a plurality of substrates simultaneously is advantageous in terms of mass production. In addition, the transmissive mask mainly used is required to be free from defects such as scratches on both sides of the photomask substrate in order to sufficiently transmit the exposure light, and double-side polishing is also effective as a countermeasure against scratches. .

A general double-side polishing apparatus is designed so that the mask substrate is polished while revolving while rotating on the polishing surface plate in order to prevent the symmetry of the mask substrate from being lost. However, since the relative speed of the substrate with respect to the surface plate is fastest at the corner of the substrate farthest from the center of rotation and slowest at the center, excessive polishing tends to occur at the corner of the substrate. Therefore, it is necessary to devise polishing conditions in order to maintain the symmetry of the mask substrate and to make the degree of polishing uniform at the center and corners of the substrate.
For example, a method of finishing a substrate with high flatness by mixing abrasives having different particle sizes and performing polishing has been proposed (see Patent Document 1). Also, after making a concave substrate under the condition that the central part of the substrate is polished quickly by the double-side polishing apparatus, the flatness is high by polishing under the condition that the peripheral part is polished faster by the single-side polishing apparatus. A method for obtaining a substrate has been proposed (see Patent Document 2).

Since the single-side polishing apparatus can more uniformly control the pressure acting between the polishing cloth and the substrate, it is generally used particularly in finishing polishing. FIG. 7 schematically shows a configuration of a general single-side polishing apparatus 21. The photomask substrate 27 is sucked and held by the polishing head 26, and the surface plate 24 and the polishing head 26 to which the polishing cloth 25 is attached are rotated in predetermined directions. Polishing is performed by supplying the polishing agent 22 from the polishing agent supply nozzle 23 to the polishing cloth 25 and pressing the substrate 27.
However, when higher flatness is required for the photomask substrate, it is extremely difficult to obtain a substrate having high flatness over the entire surface even if polishing is performed using a single-side polishing apparatus. The problem of overpolishing is likely to occur.

  Therefore, when the photomask substrate is polished using the single-side polishing apparatus 21 as described above, there is a method of polishing using an annular jig called a guide ring 30 as shown in FIG. The photomask substrate 27 is held in a guide ring 30 provided in the polishing head and pressed against the polishing cloth with a predetermined pressure. By pressing the polishing cloth around the substrate 27 by the guide ring 30, an effect of suppressing excessive polishing of the peripheral portion of the substrate 27 can be obtained.

However, even when the photomask substrate 27 is polished using the guide ring 30, the corner portion of the substrate 27 is farthest from the center of rotation, so that the relative speed with the polishing cloth is high and the polishing is more fresh. Since the agent is easily supplied, over-polishing is likely to occur at the corners.
In addition, when trying to obtain a substrate having good flatness from a photomask substrate having a distorted target, the effect of correcting the flatness can be obtained even by using a general guide ring 30 as shown in FIG. There is a problem that can not be.

  On the other hand, a method of dividing the guide ring into several parts and independently controlling the pressing of each part has been proposed (see Patent Documents 3 and 4). For example, in the guide ring 40 divided into eight as shown in FIG. 9, the step pieces 41, 43, 45, 47 corresponding to the corners of the substrate have step pieces 42, 44, 46 corresponding to the side portions of the substrate. , 48 is set to a pressure stronger than that for polishing. In this way, it is possible to reduce the difference in polishing rate between the side portion and the corner portion of the substrate by performing the polishing by individually controlling the pressing of the step pieces 41 to 48 of the guide ring 40. Yes.

Further, as a means for finishing a mask substrate having high flatness, a method has been proposed in which pressure control is independently performed on a substrate by a plurality of pressure bodies (see Patent Document 5).
However, control by these methods is technically very difficult, and high flatness may not always be achieved even when the substrate is polished by these methods.

JP 2004-314294 A JP 2005-43838 A JP 2003-48148 A JP 2003-51472 A Japanese Patent Laid-Open No. 2004-29735

  In view of the above problems, the present invention mainly provides a guide ring that can be easily and reliably finished into a square substrate having high flatness when polishing a square substrate such as a photomask substrate. And

  In order to achieve the above object, according to the present invention, when polishing while pressing a square substrate against a polishing cloth, the polishing cloth is pressed around the substrate so that the peripheral portion of the substrate is excessive. A guide ring for preventing polishing, which has a housing portion for housing the substrate, and at least a part of the periphery of the housing portion that leads to the outside of the guide ring on a surface in contact with the polishing cloth A square substrate polishing guide ring characterized in that a notch is formed is provided (claim 1).

  In such a square substrate polishing guide ring, the portion facing the notch in the peripheral part of the square substrate accommodated in the accommodating portion is relatively many from the outside of the guide ring through the notch. The polishing agent is supplied and the elastic force of the polishing cloth is strongly received, so that the polishing is promoted and the polishing efficiency is improved. Therefore, with such a guide ring, selective polishing is possible even without a complicated pressing mechanism, and the corners and sides of the substrate are polished to the same extent or the symmetry is lost. The flatness of the substrate can be corrected, and a square substrate having high flatness and symmetry can be easily and reliably finished.

The housing portion may house a square prismatic substrate (claim 2).
Since a photomask substrate requiring high flatness is generally rectangular, the guide ring as described above can be preferably used.

For the rectangular substrate, the notch is formed at a position corresponding to at least one side of the rectangular substrate accommodated in the accommodating portion (Claim 3), preferably at a position corresponding to each side. It may be a guide ring (claim 4).
A square substrate is more easily polished at the corner than at the side, but if a guide ring having a notch formed at a position corresponding to the side of the substrate is used, the corresponding side of the substrate Polishing is promoted, and the corner and side portions can be polished at substantially the same polishing rate.

The cutout portion may be formed so as to become wider from the housing portion toward the outside (Claim 5).
Thus, if the notch part which becomes wide toward the exterior is formed, it will become easy to attract an abrasive | polishing agent from the outer side of a guide ring through a notch part, and it can improve polishing efficiency reliably.

In addition, a portion where the clearance with the substrate is larger than the position corresponding to the corner portion of the substrate is formed at a position corresponding to the side of the square substrate, and the notch portion communicating with the large clearance and the outside is formed. It can also be formed so as to communicate (claim 6).
With such a guide ring, the large clearance portion formed between the guide ring and the side portion of the substrate has the abrasives drawn from the outside through the cutouts and the polishing cloth sinks. Get smaller. Therefore, the polishing efficiency of the side portion of the substrate is further improved, and a square substrate having high flatness and symmetry can be finished.

  Further, according to the present invention, there is provided a polishing head for holding a square substrate and pressing the substrate against a polishing cloth for polishing, and at least a substrate holding means for sucking and holding the substrate, A square substrate polishing head comprising a substrate pressing means for pressing a substrate against a polishing cloth and the guide ring according to the present invention is provided.

  In the polishing head provided with the guide ring according to the present invention, a relatively large amount of abrasive is supplied from the outside of the guide ring to the portion where the notch is formed during polishing, Subduction is reduced, and polishing of the peripheral portion of the corresponding substrate can be promoted. Therefore, if this polishing head is used, position-selective polishing can be performed even without a complicated pressing mechanism, and a square substrate having high flatness and symmetry can be easily and surely finished.

  Furthermore, according to the present invention, the guide ring according to the present invention is used in a method of holding a square substrate, supplying an abrasive to the polishing cloth, and polishing while pressing the substrate against the polishing cloth. A polishing method for a rectangular substrate is provided in which the rectangular substrate is accommodated in the accommodating portion of the guide ring to perform polishing (Claim 8).

  If the square substrate is polished using the guide ring according to the present invention, the portion facing the cutout portion of the peripheral portion of the square substrate accommodated in the accommodating portion is relative to the outside of the guide ring. In addition, a large amount of abrasive is supplied, and the subsidence of the polishing cloth is reduced, so that the elastic force of the polishing cloth is strongly received. Therefore, according to this method, even when a complicated pressing mechanism is not provided, the polishing rate can be increased in a position-selective manner, and a square substrate having high flatness and symmetry can be easily and surely finished. be able to.

In this case, a photomask substrate can be polished as the square substrate.
Since the photomask substrate is a square substrate that requires particularly high flatness, the polishing method using the guide ring according to the present invention is particularly effective.

  In the guide ring according to the present invention, a cutout portion that communicates with the outside of the guide ring is formed in a part of the periphery of the housing portion on the surface in contact with the polishing pad. Of the peripheral part of the square substrate accommodated in the accommodating part, the part facing the notch is supplied with a relatively large amount of abrasive from the outside of the guide ring, and the sinking of the polishing cloth is small. As a result, the elastic force by the polishing cloth is strongly received. Therefore, when a square substrate such as a photomask substrate is polished using such a guide ring, the polishing efficiency can be improved easily and reliably in a position-selective manner, and the corners and sides of the substrate are approximately equal. The substrate can be polished at a polishing rate of 5 mm, or the flatness of the substrate whose symmetry is broken can be corrected to finish a rectangular substrate having high flatness and symmetry.

The present invention will be described in detail below.
As a result of intensive studies on polishing of a square substrate such as a photomask substrate, the present inventors have found a guide in which a cutout portion communicating with the outside of the guide ring is formed in a part of the periphery of the housing portion for housing the substrate. In the case of a ring, the portion of the peripheral portion of the substrate that faces the notch portion of the guide ring is polished by receiving a relatively large amount of abrasive and receiving the strong elastic force of the polishing cloth. Found that can be promoted. Therefore, if the guide ring is formed with a notch that leads to the outside at a position corresponding to the portion where the polishing speed of the peripheral portion of the square substrate is desired to be increased, the peripheral portion of the substrate is polished almost uniformly or symmetrically. The present inventors have found that the flatness of a substrate having a deteriorated property can be corrected and the substrate can be finished as a whole with a high flatness, and the present invention has been completed.

Hereinafter, a more specific description will be given with reference to the accompanying drawings.
FIG. 1 schematically shows an example of a guide ring for a square substrate according to the present invention. The guide ring 1 has an accommodating portion 2 corresponding to the shape of the substrate 6 in order to accommodate a rectangular photomask substrate 6. The surface 3 of the guide ring 1 that is in contact with the polishing cloth has a cutout portion that leads from the housing portion 2 to the outside of the guide ring 1 at a position corresponding to each side 6a of the substrate 6 that is housed in the housing portion 2. 4 is formed. Each notch 4 is formed to be wide toward the outside, and is so shaped as to be an opening.
On the other hand, support portions 5 that are positioned by supporting the corner portions 6 b of the substrate 6 are formed at positions corresponding to the corner portions 6 b of the four corners of the substrate 6.

  The material of the guide ring 1 is not particularly limited, but synthetic resin such as vinyl chloride resin, PPS, and PEEK can be used from the viewpoint of preventing scratches and contamination on the substrate in addition to moldability and durability. Further, quartz which is the same material as the photomask substrate can be used.

  2A and 2B schematically show a cross section of the polishing head 10 provided with the guide ring 1 shown in FIG. 1, and FIG. 2A shows the AA ′ line in FIG. FIG. 2B shows a cross section taken along line BB ′. The polishing head 10 has a rectangular top ring 9 similar to the substrate 6 as a means for holding the photomask substrate 6 and pressing it against the polishing cloth 13, and a circular guide ring surrounding the top ring 9. 1 is provided.

  Inside the top ring 9 is formed a ventilation path 8 for vacuum suction of the substrate 6. Further, a rubber ring (rubber packing) 7 is attached to the lower surface of the top ring 9 so as to be in contact with the peripheral portion on the back surface side of the substrate 6. The rubber ring 7 is for sealing the space between the top ring 9 and the substrate 6 and holding the substrate 6 by vacuum suction, and is made of silicone rubber, nitrile rubber, styrene butadiene rubber, fluorine rubber, or the like. Can do. Alternatively, a ring made of a synthetic resin such as a polyacetal resin or a fluorine resin can be used. By using such a ring 7 made of rubber or synthetic resin, the substrate 6 can be adsorbed and held without being scratched. However, in order to more reliably prevent the contamination of the substrate 6 and the influence of the scratch on the exposure of the photomask, the rubber ring 7 has a peripheral portion on the back surface that does not affect the exposure of the photomask, for example, the outermost peripheral portion (edge) of the substrate 6. Part) is preferably provided so as to be in contact with an area of 1 to 3 mm.

  When polishing by holding the photomask substrate 6 with such a polishing head 10, first, the substrate 6 is accommodated in the accommodating portion 2 of the guide ring 1. The four corners 6b of the substrate 6 are positioned by being supported by the support portions 5 of the guide ring 1. The substrate 6 is sucked and held via the rubber ring 7 by vacuum suction through the ventilation path 8.

  The surface plate to which the polishing cloth 13 is attached and the polishing head 10 are each rotated in a predetermined direction to supply an abrasive to the polishing cloth 13 and the substrate 6 held by the polishing head 10 is attached to the polishing cloth 13. Press. At this time, since a load is applied to the peripheral portion of the substrate 6 via the rubber ring 7, the peripheral portion is easily polished. Therefore, if the substrate 6 is brought into contact with the polishing cloth 13 and then air or nitrogen is supplied through the air passage 8 to pressurize the back side of the substrate 6, the polishing load of the entire substrate can be made substantially uniform. The suction of the substrate 6 is released by supplying air or the like from the air passage 8 and pressurizing it, but since at least the corner 6b of the substrate 6 is supported in the accommodating portion 2 of the guide ring 1, The substrate 6 is not displaced in the guide ring 1 or detached from the guide ring 1.

The top ring 9 and the guide ring 1 may be controlled to be pressed by the same pressing mechanism, or a pressing mechanism for the guide ring 1 may be provided separately from the pressing mechanism of the top ring 9.
The abrasive can be supplied from the outside of the polishing head as in the polishing apparatus of FIG. 7, but a mechanism for supplying the abrasive to the inside of the polishing head may be provided.
Further, instead of the rubber ring 7, the substrate 6 may be held via a rubber backing pad 11 as shown in FIG. By using the backing pad 11 having a large number of ventilation holes formed on the entire surface, the substrate 6 can be vacuum-sucked through the ventilation path 8 of the top ring 9, and the entire surface of the substrate 6 is pressed uniformly through the backing pad 11. be able to.

As described above, when polishing is performed by sliding the substrate 6 and the polishing pad 13 using the guide ring 1 according to the present invention, as shown in FIG. The abrasive is drawn through the opening 4 of the guide ring 1. Further, since the sinking of the polishing cloth 13 is reduced under the opening 4 of the guide ring 1, the central portion of each side 6 a of the substrate 6 facing the opening 4 is strongly subjected to the elastic force by the polishing cloth 13. Become. That is, a relatively large amount of abrasive is supplied to the central portion of the side 6a of the photomask substrate 6 accommodated in the accommodating portion 2, and polishing is promoted by receiving strong elastic force from the polishing cloth 13. Will be.
On the other hand, around the corner portion 6b of the substrate 6, the polishing cloth 13 is pressed and greatly sunk by the support portion 5 of the guide ring 1 as seen in FIG. Therefore, in the vicinity of the corner portion 6b of the substrate 6, since the amount of abrasive supplied is small and the elastic force of the polishing pad 13 is small compared to the central portion of the side 6a, polishing is suppressed.

  In other words, if polishing is performed while holding the square photomask substrate 6 with the polishing head 10 having such a guide ring 1, the center portion of the side 6a of the substrate 6 where the polishing speed is generally reduced is relative. In addition, the polishing efficiency is relatively reduced in the vicinity of the corner portion 6b where the polishing efficiency is increased and the polishing rate is likely to be increased, and overpolishing can be effectively prevented. As a result, a photomask substrate having high flatness over the entire periphery of the substrate 6 can be finished.

In the present invention, the shapes of the top ring, the guide ring and the like are not limited to those shown in FIGS. 1 and 2, and other shapes can also be adopted.
FIG. 4 shows another example of the guide ring according to the present invention. The guide ring 51 has a notch portion (opening portion) 54 that is wide from the housing portion 52 toward the outside at a position corresponding to one side 6 a of the photomask substrate 6 on the surface in contact with the polishing cloth. Is formed. Such a guide ring 51 can be suitably used when correcting the flatness of a substrate whose symmetry has been lost. For example, in the initial polishing, when the double-side polishing apparatus is used to polish the left and right sides of the substrate so that the symmetry is lost, in order to increase the flatness of the substrate, the side of the substrate 6 to be scraped further faces the opening 54. Is contained and polished. Since a relatively large amount of abrasive is supplied to the portion facing the opening 54 and elastic force is strongly received by the polishing cloth, the polishing is promoted and the flatness is greatly improved. Therefore, if such a guide ring 51 is used, position-selective polishing can be performed without providing a complicated pressing mechanism, and the flatness of the substrate whose symmetry is broken can be corrected.

Moreover, the notch part of the guide ring which concerns on this invention is not limited to the shape which becomes wide toward the exterior as shown to FIG. 1, FIG. 4, For example, it is good also as a groove | channel shape from which a width | variety becomes substantially constant.
In the guide ring shown in FIG. 5, a portion where the clearance 65 with the substrate 6 is larger than the position corresponding to the corner 6 b of the substrate 6 is formed at a position corresponding to one side 6 a of the photomask substrate 6. The large clearance 65 communicates with notches (grooves) 64a and 64b communicating with the outside of the guide ring 61. When the photomask substrate 6 is accommodated in the accommodating portion 62 of the guide ring 61 and polished, the abrasive is taken into the clearance 65 from the outside of the guide ring 61 through the groove portions 64a and 64b, and a large clearance is obtained. In the portion where 65 is formed, the sinking of the polishing cloth is reduced. That is, the central portion of the side 6a of the substrate 6 on which the large clearance 65 is formed is supplied with a relatively large amount of polishing agent and is strongly polished by receiving an elastic force from the polishing cloth. Become. Therefore, if this guide ring 61 is used, position-selective polishing can be performed without providing a complicated pressing mechanism, and the flatness of the substrate whose symmetry is broken can be corrected.

  Note that the number of clearances and the number of grooves, positions, shapes, and the like are not limited to those shown in FIG. For example, as shown in FIG. 6, if the guide ring 71 is formed with a large clearance 75 and grooves 74 a and 74 b communicating with each other at positions corresponding to the four sides 6 a of the substrate 6, The polishing efficiency can be relatively increased at the center portion of the side 6a, and the polishing efficiency can be decreased around the corner portion 6b. As a result, a photomask substrate having high flatness over the entire periphery of the substrate 6 can be finished.

Further, the clearance and the groove communicating with the clearance are not limited to the forms shown in FIGS. 5 and 6, and may be formed at positions corresponding to two or three sides of the photomask substrate, if necessary.
Further, when it is desired to further promote polishing at the corner of the photomask substrate according to the purpose, an opening leading to the outside as shown in FIG. 1 may be provided at a position corresponding to the corner, or FIG. A large clearance and a groove communicating with the large clearance may be provided.
Further, the guide ring is not limited to a circular one, and may be a rectangular guide ring 91 as shown in FIG. 13, for example. The guide ring 91 has an opening 94 having a constant width at a position corresponding to each side of the rectangular substrate.

  As described above, when polishing is performed by holding the photomask substrate with the polishing head having the guide ring according to the present invention, for example, a flat area of 0.3 μm or less in the region excluding the innermost 5 mm from the outermost peripheral portion of the substrate. Degree can be achieved. When a photomask is manufactured using the polished photomask substrate, a photomask capable of stably transferring a high-density integrated circuit such as LSI or VLSI onto a semiconductor wafer can be obtained.

Examples of the present invention and comparative examples will be described below.
(Example)
As shown in FIG. 10, a rectangular guide ring 81 (manufactured by PPS) in which openings (notches) 84 that are widened outwardly at positions corresponding to the respective sides of the photomask substrate 6 were formed. . The guide ring 81 was mounted on a polishing head, and a 152 mm × 152 mm × 6.35 mm synthetic quartz glass substrate was polished using a single-side polishing apparatus. In the polishing, the pressing load of the substrate was 20 kPa, colloidal silica was used as the polishing agent, and a polishing cloth was used for polishing for 10 minutes. The polishing was started from the concave substrate, and the point in time when the central portion of the side of the substrate was almost the same height as the central portion of the substrate was used as a guideline for finishing the polishing.
Before and after polishing, the flatness of an inner region of 142 mm × 142 mm was measured. FIG. 11 shows the flatness of the substrate before and after polishing. The flatness before polishing (A) was 0.314 μm, but after polishing (B), a flatness of 0.139 μm was achieved.

(Comparative example)
The synthetic quartz glass substrate was polished in the same manner as in the example using a guide ring having no notch on the polishing side surface as shown in FIG. 8 and a constant clearance.
Before and after polishing, the flatness of an inner region of 142 mm × 142 mm was measured. FIG. 12 shows the flatness of the substrate before and after polishing. The flatness before polishing (A) was 0.322 μm, but the flatness after polishing (B) was deteriorated to 0.376 μm. In particular, overpolishing at the corners of the four corners was significant compared to the sides.

  The present invention is not limited to the above embodiment. The above embodiment is merely an example, and the present invention has the same configuration as that of the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  For example, in the above embodiment, the case of polishing a substantially square photomask substrate has been described. However, the rectangular substrate to be polished according to the present invention is not limited to this, and high flatness such as a liquid crystal substrate or a disk substrate is required. It can also be applied to polishing a square substrate, and the shape of the substrate may be a rectangular substrate or a polygonal substrate.

  Further, the guide ring according to the present invention can improve the polishing efficiency at the portion facing the notch, so that position selective polishing is possible without providing a complicated pressing mechanism for the guide ring. In order to further enhance the polishing effect, a plurality of pressing mechanisms may be provided to partially increase the weight of the guide ring, or the guide ring may be divided into a plurality of parts.

It is a schematic plan view which shows an example of the guide ring which concerns on this invention. It is a schematic sectional drawing which shows an example of the grinding | polishing head provided with the guide ring of FIG. (A) AA 'line cross section (B) BB' line cross section It is a schematic sectional drawing which shows the state which hold | maintained the board | substrate via the backing pad. It is a schematic plan view which shows the other example of the guide ring which concerns on this invention. It is a schematic plan view which shows the other example of the guide ring which concerns on this invention. It is a schematic plan view which shows the other example of the guide ring which concerns on this invention. It is the schematic which shows an example of a structure of a single-side polish apparatus. It is a schematic plan view which shows an example of the general guide ring for square substrates. It is a schematic plan view which shows an example of the divided | segmented guide ring. It is a schematic plan view which shows the guide ring used in the Example. It is a figure which shows the flatness of the board | substrate before and behind grinding | polishing in an Example. (A) Before polishing (B) After polishing It is a figure which shows the flatness of the board | substrate before and behind grinding | polishing in a comparative example. (A) Before polishing (B) After polishing It is a schematic plan view showing a square guide ring according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Guide ring, 2 ... Storage part, 3 ... Surface on the side which contacts polishing cloth, 4 ... Notch part (opening part), 5 ... Support part, 6 ... Photomask substrate, 6a ... Side part, 6b ... Corner part, 7 ... Rubber ring (rubber packing), 8 ... Air passage, 9 ... Top ring, 10 ... Polishing head, 11 ... Backing pad, 13 ... Polishing cloth, 64a, 64b ... Notch part (groove part), 65 ... clearance.

Claims (9)

  A guide ring for preventing excessive polishing of a peripheral portion of a substrate by pressing the polishing cloth around the substrate when the square substrate is polished against the polishing cloth. And a notch that communicates with the outside of the guide ring is formed in a part of the periphery of the accommodating portion at least on the surface in contact with the polishing pad. Guide ring for mold substrate polishing.   The square substrate polishing guide ring according to claim 1, wherein the accommodating portion accommodates a rectangular prismatic substrate.   3. The rectangular substrate polishing according to claim 1, wherein the notch is formed at a position corresponding to at least one side of the rectangular substrate accommodated in the accommodating portion. Guide ring.   4. The square substrate polishing guide ring according to claim 3, wherein the notch is formed at a position corresponding to each side of the square substrate accommodated in the accommodating portion.   5. The guide ring for polishing a square substrate according to claim 1, wherein the cutout portion is formed to be wide from the housing portion toward the outside. 6. .   A portion where the clearance with the substrate is larger than the position corresponding to the corner portion of the substrate is formed at a position corresponding to the side of the square substrate, and the large clearance and a cutout portion communicating with the outside communicate with each other. 6. The square substrate polishing guide ring according to claim 1, wherein the guide ring is formed as described above.   A polishing head for holding a square substrate and pressing the substrate against a polishing cloth for polishing, at least a substrate holding means for adsorbing and holding the substrate, and pressing the substrate against the polishing cloth A polishing head for a square substrate, comprising: the substrate pressing means; and the guide ring according to any one of claims 1 to 6.   The method according to any one of claims 1 to 6, wherein the substrate is held, the abrasive is supplied to the polishing cloth, and the substrate is pressed against the polishing cloth while being polished. A method for polishing a square substrate, comprising: using a guide ring; and storing the square substrate in a receiving portion of the guide ring to perform polishing.   The method for polishing a square substrate according to claim 8, wherein a photomask substrate is polished as the square substrate.

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