Circuit board holder, circuit board housing case, circuit board holding method, and circuit board housing method

Abstract

The purpose of the present invention is to minimize abrasion powder (dust) generated from the surface of a substrate holder due to friction between a mask / blank substrate and the substrate holder during transportation of the mask / blank substrate.　This substrate holder, which is provided to a substrate-housing case that houses a substrate having two chamfered surfaces on one side and which comes into contact with the substrate to hold the substrate, has a first holding surface that comes into contact with part of a first chamfered surface of the two chamfered surfaces to hold the substrate, and a second holding surface that comes into contact with part of a second chamfered surface of the two chamfered surfaces to hold the substrate. The substrate holder is configured such that the first holding surface is brought into contact with one of two ridges of the first chamfered surface, and the second holding surface is brought into contact with one of two ridges of the second chamfered surface, so as to hold the substrate.

Description

Technical Field

[0001] The present invention relates to a substrate holder, a substrate storage case, a substrate holding method, and a substrate storage method.

Background Art

[0002] In the manufacturing process of liquid crystal display (LCD) panels, organic EL display (OLED) panels, etc., in a flat panel display (FPD) exposure apparatus, a photomask, which is a master plate on which a thin film transistor (TFT) circuit pattern is drawn, is irradiated with light to pattern the TFT on a glass plate. The photomask is obtained by patterning a mask blank on which a thin film such as a light shielding film or a resist film is formed on one entire surface of a glass substrate.

[0003] These photomasks and mask blanks are stored in a dedicated storage case and transported and stored (for example, Patent Document 1). In the storage case, the photomask or mask blank is supported and fixed by a substrate holder so as not to fall off or be damaged by vibrations during transportation. Hereinafter, unless otherwise particularly distinguished, the photomask and mask blank are referred to as a mask / blank substrate.

[0004] The substrate holder is required to have a hardness such that it does not damage the mask / blank substrate made of a glass substrate, and further to have a structural strength such that the mask / blank substrate does not fall off due to vibrations during transportation. In addition, it is desirable to suppress wear powder (dust) generated from the surface of the substrate holder due to friction between the mask / blank substrate and the substrate holder during transportation of the mask / blank substrate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] According to a first aspect of the disclosure, the substrate holder is provided in a substrate housing case for housing a substrate having two chamfered surfaces on one side, and is a substrate holder that contacts and holds the substrate, the substrate holder having a first holding surface that contacts a portion of the first chamfered surface of the two chamfered surfaces to hold the substrate, and a second holding surface that contacts a portion of the second chamfered surface of the two chamfered surfaces to hold the substrate, the first holding surface being in contact with one of the two ridges of the first chamfered surface, and the second holding surface being in contact with one of the two ridges of the second chamfered surface to hold the substrate.

[0007] According to a second aspect of the disclosure, the substrate holder is provided in a substrate housing case for housing a substrate, and is a substrate holder that contacts and holds the substrate, wherein the substrate holder has a holding surface that contacts and holds a portion of the substrate, and the material of the holding surface that contacts the substrate is one of polytrifluoroethylene (PCTFE), polyimide (PI), and polyetheretherketone (PEEK).

[0008] According to a third aspect of the disclosure, the substrate holder is provided in a substrate housing case for housing a substrate, and is a substrate holder that contacts and holds the substrate, wherein the substrate holder has a holding surface that contacts and holds a portion of the substrate, and the material of the holding surface is a material that does not contain polyacetal (POM), and after a tribological test is performed on a test piece made of the material measuring 50 mm in length, 50 mm in width, and 5 mm in thickness with a 5 mm diameter SiO2 glass sphere at a load of 800 g, a rotation speed of 50 rpm, and a measurement time of 1 hour, the wear depth of the test piece made of the material is 6000 nm or less, and the material does not contain polyacetal (POM).

[0009] According to a fourth aspect of the disclosure, the substrate housing case comprises the substrate holder.

[0010] According to a fifth aspect of the disclosure, the substrate holding method is a substrate holding method using a substrate holder provided in a substrate housing case for housing a substrate having two chamfered surfaces on one side, the substrate holder contacts the substrate and holds the substrate, the method comprising: a first holding surface holding step of holding the substrate by bringing one of the two ridges of the first chamfered surface to contact a first holding surface of the substrate holder; and a second holding surface holding step of holding the substrate by bringing one of the two ridges of the second chamfered surface to contact a second holding surface of the entire substrate holder.

[0011] According to a sixth aspect of the disclosure, the method for housing the substrate includes the substrate holding method described above.

[0012] Furthermore, the configuration of the embodiments described later may be modified as appropriate, and at least a part of it may be replaced with other components. Moreover, the configuration elements whose arrangement is not particularly limited may be arranged in positions that can achieve their function, not limited to the arrangement disclosed in the embodiments. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1(A) is a perspective view of the substrate housing case according to the first embodiment, Figure 1(B) is a view of the substrate housing case from the +Z direction in Figure 1(A), Figure 1(C) is a view of the substrate housing case from the -X direction in Figure 1(A), and Figure 1(D) is a view of the substrate housing case from the -Y direction in Figure 1(A). [Figure 2] Figure 2 is a plan view of the lower box section as seen from the +Z direction. [Figure 3] Figure 3(A) is a cross-sectional view of the corner holder (cross-sectional view along line AA in Figure 2), and Figure 3(B) is a cross-sectional view of the edge holder (cross-sectional view along line BB in Figure 2). [Figure 4] Figure 4 is a graph showing the measurement results of the dynamic friction coefficient for each test specimen in the ball-on-disk test. [Figure 5] Figure 5 is a graph showing the measurement results of the wear mark depth for each test piece in the ball-on-disk test. [Figure 6] Figure 6 is a graph showing the total amount of organic compound components classified as Category 2 detected for each sample. [Figure 7] Figure 7 is a graph showing the results of the transport test. [Figure 8] Figure 8(A) is a cross-sectional view of the corner holder according to the second embodiment, and Figure 8(B) is a cross-sectional view of the edge holder according to the second embodiment. [Figure 9] Figures 9(A) and 9(B) are cross-sectional views showing the model used in the simulation. [Figure 10] Figure 10 is a graph showing the simulation results of an index that relatively indicates the stress generated in the substrate holder with respect to the contact angle θ, when μ = 0.1. [Figure 11] Figure 11 is a graph showing the results of the transport test. [Figure 12] Figure 12 is a cross-sectional view showing a modified example of a side retainer. [Modes for carrying out the invention]

[0014] During transport of masks / blank substrates in substrate housing cases, vibrations generated during transport cause the masks / blank substrates to reciprocate slightly, resulting in friction between the masks / blank substrates and the substrate holders, which can cause wear on the holders. If a large amount of wear dust is generated due to the wear on the surface of the substrate holders, there is a risk that fine dust particles may adhere to the surface of the masks / blank substrates.

[0015] While dust adhering to the mask / blank substrate can generally be removed by washing, if the dust is not completely removed, the remaining dust on the mask / blank substrate may cause pattern defects in the process of patterning the mask blank to form a photomask, or in the process of loading the photomask into an FPD (Flat Panel Display) exposure apparatus and performing pattern transfer exposure on the mother glass.

[0016] Therefore, it is required to reduce the abrasion powder generated during transportation and storage.

[0017] 《First Embodiment》 Hereinafter, the substrate storage case according to the first embodiment will be described with reference to the drawings. FIG. 1(A) is a perspective view of the substrate storage case 1 according to the first embodiment, FIG. 1(B) is a view of the substrate storage case 1 as seen from the +Z direction in FIG. 1(A), FIG. 1(C) is a view of the substrate storage case 1 as seen from the -X direction in FIG. 1(A), and FIG. 1(D) is a view of the substrate storage case 1 as seen from the -Y direction in FIG. 1(A). Note that the shapes, lengths, thicknesses, etc. of each part shown in the embodiment do not necessarily match the actual objects, and in each figure, for the sake of easy understanding, the illustration of some elements may be omitted.

[0018] <Substrate Storage Case> The substrate storage case 1 is a case for storing a mask / blank substrate inside the case and protecting and transporting the stored mask / blank substrate.

[0019] The size of the mask / blank substrate is, for example, 1220×1400×13 mm (diagonal dimension is about 1.8 m), and the mass is, for example, about 93 kg.

[0020] The substrate storage case 1 includes an upper case unit 10 and a lower case unit 20. When storing a mask / blank substrate in the substrate storage case 1, since the substrate storage case 1 is placed on the floor surface so that the bottom plate of the lower case unit 20 is parallel to the floor surface, the Z direction may be referred to as the vertical direction or the gravitational direction in the following description. Note that the substrate storage case 1 shown in FIG. 1(A) is of a type that transports the mask / blank substrate with the substrate storage case 1 upright (so that the bottom plate of the lower case unit 20 is perpendicular to the floor surface) during transportation, but the substrate storage case 1 may also be of a type that transports the mask / blank substrate with the substrate storage case 1 lying horizontally (so that the bottom plate of the lower case unit 20 remains parallel to the floor surface) during transportation.

[0021] The upper case unit 10 includes a metal upper frame 11 and a resin upper box section 12 attached to the upper frame 11. The lower case unit 20 includes a metal lower frame 21 and a resin lower box section 22 attached to the lower frame 21.

[0022] The upper box section 12 has a lid plate that covers the main surface of the mask / blank substrate, and side walls that extend downward, connected to the side edges of the lid plate, and is configured as a box that opens downward.

[0023] Casters 30 for movement are attached to the upper frame 11 and the lower frame 21, respectively. Handles 31 used when moving the circuit board housing case 1 are also attached to the upper frame 11 and the lower frame 21.

[0024] Figure 2 is a plan view of the lower box section 22 as seen from the +Z direction. As shown in Figure 2, the lower box section 22 has a bottom plate 22a that covers the main surface of the mask / blank substrate, and side walls 22b to 22e that are connected to the side edges of the bottom plate 22a and extend upward, and is configured as a box that opens upward.

[0025] A mating structure is formed at the mating surface between the lower end of the upper box section 12 and the upper end of the lower box section 22, allowing them to fit together. When the upper case unit 10 is placed over the lower case unit 20 from above and connected with bolts or the like, the mask / blank substrate housed inside the substrate housing case 1 is held in a sealed state.

[0026] Inside the lower box section 22, a substrate holder 23 is provided to hold the edges of the mask / blank substrate in the thickness direction. The substrate holder 23 includes L-shaped corner holders 23a provided at four locations to support the corners of the mask / blank substrate, and edge holders 23b provided to support the center of each side of the mask / blank substrate.

[0027] Figure 3(A) is a cross-sectional view of the corner holder 23a (cross-sectional view along line AA in Figure 2), and Figure 3(B) is a cross-sectional view of the edge holder 23b (cross-sectional view along line BB in Figure 2). Note that the mask / blank substrate 2 is also shown in Figures 3(A) and 3(B).

[0028] As shown in Figure 3(A), the corner holder 23a comprises a first member 23a1 and a second member 23a2. The first member 23a1 has a holding surface 24a1 that contacts the mask / blank substrate 2 and holds the mask / blank substrate 2. When the substrate housing case 1 is placed on the floor so that the bottom plate 22a of the lower case unit 20 is parallel to the floor, the holding surface 24a1 holds the mask / blank substrate 2 from below. The holding surface 24a1 is subjected to one of the following processes: dry cutting, wet cutting, or buff polishing.

[0029] The mask / blank substrate 2 has a first main surface 2a, a second main surface 2b, a side surface 2c, a first connecting surface (first chamfered surface) 2d connecting the first main surface 2a and the side surface 2c, and a second connecting surface (second chamfered surface) 2e connecting the second main surface 2b and the side surface 2c. In the case of a photomask, the first main surface 2a is, for example, the surface on which a pattern is formed, and in the case of a mask blank, the first main surface 2a is, for example, the surface on which a pattern is formed. The second main surface 2b may be the surface on which a pattern is formed or the surface on which a pattern is formed. In the following description, the first main surface 2a and the second main surface 2b may be simply referred to as main surfaces 2a and 2b.

[0030] The retaining surface 24a1 is in contact with edge r1, which is one of two edges (edges) of the mask / blank substrate 2 where the first connection surface 2d and the first main surface 2a intersect, and edge r2 where the side surface 2c and the first connection surface 2d intersect.

[0031] The holding surface (first holding surface) 24a1 is inclined with respect to a plane PL1 that is approximately parallel to the main surface (first main surface 2a) of the mask / blank substrate 2 held by the holding surface 24a1, and the smaller of the angles θ1 between the holding surface 24a1 and the plane PL1 is, for example, 3°. Hereafter, angle θ1 may be referred to as the contact angle θ1 between the corner holder 23a and the mask / blank substrate 2. Note that the contact angle θ1 is not limited to 3°, and may be less than 3° or greater than 3°. Also, plane PL1 is approximately perpendicular or perpendicular to the direction of gravity.

[0032] The second member 23a2 has the same shape as the first member 23a1 and is arranged symmetrically with respect to the center line CL1 in the thickness direction of the mask / blank substrate 2. The second member 23a2 has a holding surface 24a2 that contacts the mask / blank substrate 2 and holds the mask / blank substrate 2. The holding surface 24a2 is in contact with the edge (edge ​​line portion) r3 of the mask / blank substrate 2 where the second connection surface 2e and the second main surface 2b intersect, and the edge (edge ​​line portion) r4 where the side surface 2c and the second connection surface 2e intersect.

[0033] Furthermore, the holding surface (second holding surface) 24a2 is inclined with respect to a plane PL2 that is approximately parallel to the main surface (second main surface 2b) of the mask / blank substrate 2 held by the holding surface 24a2. The smaller of the angles between the holding surface 24a2 and the plane PL2, the contact angle θ2, may be the same as the contact angle θ1 or a different angle. Note that when the substrate housing case 1 is placed on the floor so that the bottom plate 22a of the lower case unit 20 is parallel to the floor, planes PL1 and PL2 become planes perpendicular to the direction of gravity.

[0034] When the substrate housing case 1 is placed on the floor so that the bottom plate 22a of the lower case unit 20 is parallel to the floor surface, the holding surface 24a2 holds the mask / blank substrate 2 from above. The other configurations of the second member 23a2 are the same as those of the first member 23a1, so a detailed explanation is omitted. The first member 23a1 and the second member 23a2 may be formed integrally or as separate parts. If the first member 23a1 and the second member 23a2 are separate parts, the first member 23a1 is provided in the lower box section 22, and the second member 23a2 is provided in the upper box section 12. In addition, the first member 23a1 and the second member 23a2 may be in contact with each other or separated in the Z direction.

[0035] As shown in Figure 3(B), the edge holder 23b comprises a first member 23b1 and a second member 23b2. The first member 23b1 has a holding surface (first holding surface) 24b1 that contacts the mask / blank substrate 2 and holds the mask / blank substrate 2. When the substrate housing case 1 is placed on the floor so that the bottom plate 22a of the lower case unit 20 is parallel to the floor, the holding surface 24b1 holds the mask / blank substrate 2 from below. The holding surface 24b1 is subjected to one of the following processes: dry cutting, wet cutting, or buff polishing.

[0036] The retaining surface 24b1 is in contact with the edge r1 of the mask / blank substrate 2. The retaining surface 24b1 is inclined with respect to a plane PL3 that is substantially parallel to the main surface (first main surface 2a) of the mask / blank substrate 2 that the retaining surface 24b1 holds, and the smaller of the angles θ3 between the retaining surface 24b1 and the plane PL3 is, for example, 3°. Hereafter, angle θ3 may be referred to as the contact angle θ3 between the first member 23b1 of the edge retainer 23b and the mask / blank substrate 2. Note that the contact angle θ3 is not limited to 3°, and may be less than 3° or greater than 3°.

[0037] The second member 23b2 has a holding surface (second holding surface) 24b2 for holding the mask / blank substrate 2. When the substrate housing case 1 is placed on the floor so that the bottom plate 22a of the lower case unit 20 is parallel to the floor, the holding surface 24b2 holds the mask / blank substrate 2 from above. The holding surface 24b2 is subjected to one of the following processes: dry cutting, wet cutting, or buff polishing.

[0038] The retaining surface 24b2 is in contact with edge r3, which is the edge where the second connection surface 2e and the second main surface 2b of the mask / blank substrate 2 intersect, and edge r4, which is the edge where the side surface 2c and the second connection surface 2e intersect.

[0039] The holding surface 24b2 is inclined with respect to a plane PL4 that is substantially parallel to the main surface (second main surface 2b) of the mask / blank substrate 2 held by the holding surface 24b2, and the smaller of the angles θ4 between the holding surface 24b2 and the plane PL4 is, for example, 3°. Hereafter, angle θ4 may be referred to as the contact angle θ4 between the second member 23b2 of the edge holder 23b and the mask / blank substrate 2. Note that the contact angle θ4 is not limited to 3°, and may be less than 3° or greater than 3°. Also, the contact angle θ4 may be the same angle as the contact angle θ3, or it may be a different angle. Note that when the substrate housing case 1 is placed on the floor so that the bottom plate 22a of the lower case unit 20 is parallel to the floor surface, planes PL3 and PL4 become planes perpendicular to the direction of gravity.

[0040] As indicated by arrow AR1, the second member 23b2 is movable in a plane substantially parallel to the main surface (first main surface 2a or second main surface 2b) of the mask / blank substrate 2, in a direction perpendicular to the edge of the opposing mask / blank substrate 2 (X direction or Y direction). This allows the substrate holder 23 to securely hold the mask / blank substrate 2. In this first embodiment, the first member 23b1 and the second member 23b2 are separate parts, but they may be formed integrally. If the first member 23b1 and the second member 23b2 are formed integrally, the entire edge holder 23b moves in a plane substantially parallel to the main surface (first main surface 2a or second main surface 2b) of the mask / blank substrate 2, in a direction perpendicular to the edge of the opposing mask / blank substrate 2. When the first member 23b1 and the second member 23b2 are separate, the first member 23b1 is provided in the lower box portion 22, and the second member 23b2 is provided in the upper box portion 12. Furthermore, the first member 23b1 and the second member 23b2 may be in contact with each other or separated in the Z direction.

[0041] (Materials for the substrate holder 23) The material for the substrate holder 23 is a material in which, after a tribological test is performed on a test piece made of the material measuring 50 mm in length, 50 mm in width, and 5 mm in thickness, using a 5 mm diameter SiO2 glass sphere with a load of 800 g, a rotation speed of 50 rpm, and a measurement time of 1 hour, the wear depth of the test piece is 6000 nm or less. The performance required for a holder for mask / blank substrates is to minimize the amount of wear dust generated, so a material with low wear, i.e., a material with excellent wear resistance, is suitable as the material for the substrate holder 23.

[0042] Furthermore, the material of the substrate holder 23 is such that the total amount of alkane compounds detected by a chromatographic mass spectrometer during the holding of a test piece made of the material, measuring 50 mm in length, 50 mm in width, and 5 mm in thickness, at 100°C for 300 minutes is 20 μg or less, preferably 5 μg or less. This is because it is desirable to avoid as much as possible the adhesion of relatively large molecular weight alkane components to the surface of the mask blank.

[0043] Alkane compounds include, for example, at least one of decane, undecane, dodecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, and docosane.

[0044] We investigated the specific material of the substrate holder 23 that satisfies the above conditions.

[0045] <Tribology Testing> Tribological tests were performed on test specimens (sometimes referred to as samples) made from the materials shown in Table 1 below, which were processed from a plate measuring 50 mm in length, 50 mm in width, and 5 mm in thickness. [Table 1]

[0046] The material of sample E1 is PCTFE (polytrifluoroethylene chloride), and the surface was wet-milled. The material of sample E2 is PCTFE (polytrifluoroethylene chloride), and the surface was dry-milled. The material of sample E3 is Delrin® DRL-NA, a homopolymer POM (homopolymer polyacetal), and the surface was dry-milled. The material of sample E4 is Delrin® DRL-NA, a homopolymer POM, and the surface was polished. The material of sample E5 is Duracon® M90-44, a copolymer POM (copolymer polyacetal), and the surface was dry-milled. Rice processing was performed. The material of sample E6 is Duracon® NW-02 copolymer POM, and the surface was dry milled. The material of sample E7 is Duracon® NW-02LV copolymer POM, and the surface was dry milled.

[0047] Sample E8 is made of Sepra Standard PI (polyimide), and its surface was dry-milled. Sample E9 is made of Sepra G1 PI, and its surface was buffed. Sample E10 is made of Sepra G2 PI, and its surface was buffed. Sample E11 is made of Vesper® SP-1 PI, and its surface was buffed. Sample E12 is made of Vesper® SP-21 PI, and its surface was buffed. Sample E13 is made of PVX Black PEEK (polyetheretherketone), and its surface was dry-milled. Sample E14 is made of PVX Black PEEK, and its surface was polished. Sample E15 is made of Ketron CA30 PEEK, and its surface was dry-milled. The material of sample E16 is PEEK Ketron CA30, and the surface was buffed to a polished finish.

[0048] The material of sample C1 is PE (polyethylene) Polystone® M-Sapphire. Sample C2 is made of PE polystone (registered). Sample C3 is made of M-Sapphire (trademark) and its surface was dry-milled. Sample C4 is made of PE AS plate and its surface was polished. Sample C5 is made of PTFE (polytetrafluoroethylene) and its surface was wet-milled. Sample C6 is made of PTFE and its surface was dry-milled.

[0049] Sample C7 is made of PTFE containing 15% glass and 5% molybdenum, and its surface was dry-milled. Sample C8 is made of PTFE containing 60% bronze, and its surface was dry-milled. Sample C9 is made of PTFE containing 10% carbon fiber, and its surface was dry-milled. Sample C10 is made of PTFE containing 15% carbon fiber, and its surface was dry-milled. Sample C11 is made of PTFE containing 15% carbon fiber, and its surface was wet-milled. Sample C12 is made of PTFE containing 15% graphite fiber, and its surface was dry-milled. Sample C13 is made of PTFE containing 30% graphite fiber, and its surface was wet-milled.

[0050] Sample C14 is made of PTFE with 15% glass fiber, and its surface was dry-milled. Sample C15 is made of PTFE with 15% glass fiber, and its surface was wet-milled. Sample C16 is made of PTFE with 20% glass fiber, and its surface was dry-milled. Sample C17 is made of PTFE with 20% glass fiber, and its surface was wet-milled. Sample C18 is made of PTFE with 25% glass fiber, and its surface was dry-milled.

[0051] The materials used for samples C1 to C6, PE and PTFE, are commonly used in conventional substrate holders.

[0052] <Friction and wear characteristics> To evaluate the friction and wear characteristics of the above samples, a ball-on-disk test was conducted. The ball-on-disk test was performed using a friction and wear testing machine (Friction Player: FPR-2100) manufactured by RHESCA Co., LTD.

[0053] Quartz (SiO2) glass was selected as the material for the balls that rotate and slide in contact with each test piece. This is because, in actual operation, the mask / blank substrate that comes into contact with the substrate holder is made of quartz glass.

[0054] (Friction characteristics) In evaluating the friction characteristics, a ball-on-disk test was performed on test pieces of each material under the following measurement condition 1, and the coefficient of dynamic friction of each test piece was evaluated. Measurement condition 1: Ball: SiO2 glass sphere with a diameter of 10 mm Rotation speed: 50 rpm Load: 50g Measurement time: 3600 seconds Temperature: 24℃ Humidity: 40%

[0055] Figure 4 shows the measurement results of the dynamic friction coefficient for each test piece. In the graph in Figure 4, the vertical axis represents the measured dynamic friction coefficient. A smaller dynamic friction coefficient indicates a material with low friction and excellent sliding properties. Conversely, a larger dynamic friction coefficient makes it easier to generate dust due to friction, and poor sliding properties mean that the force from the collision between the substrate holder and the mask / blank substrate is not easily dissipated, which increases the risk of damage to the glass edge.

[0056] In general, sliding components are required to be designed so that the coefficient of dynamic friction is 0.1 or less. Therefore, it is preferable to select materials with a coefficient of dynamic friction of less than 0.1 as candidates for the material of the substrate holder 23.

[0057] (Wear characteristics) In evaluating the wear characteristics, a ball-on-disk test was performed on test specimens of each material under the following measurement condition 2, forming concentric wear marks on each specimen. Subsequently, the depth, width, and surface roughness of the wear marks were measured using a surface profiler (stylus profiler: Tencor P-16+) manufactured by KLA Corporation. Measurement condition 2: Ball: 5mm diameter SiO2 glass sphere Rotation speed: 50 rpm Load: 800g Measurement time: 3600 seconds Temperature: 24℃ Humidity: 40%

[0058] Figure 5 shows the measurement results of the wear mark depth for each test specimen. In the graph in Figure 5, the vertical axis represents the wear mark depth (nm). The deeper the wear mark, the greater the amount of wear caused by the ball-on-disk test. The volume of material removed by wear is detached from the material as fine powder. In other words, a large amount of wear means a large amount of wear powder is generated. From Figure 5, it can be seen that the amount of wear varies greatly depending on the material of the test specimen.

[0059] The performance required for holders for masks / blank substrates is to minimize the amount of wear debris generated; therefore, materials with low wear, i.e., excellent wear resistance, should be selected. Focusing on samples C5 to C18, which are made of PTFE-based material, it is clear that the wear marks are significantly deep regardless of the presence or absence of additives, indicating poor wear resistance and a large amount of wear debris generation. The purpose of adding glass fibers, carbon fibers, and / or metal particles as additives to PTFE is to improve mechanical strength, enhance sliding properties, and impart conductivity. However, even with the addition of glass fibers, carbon fibers, and / or metal particles, the property of poor wear resistance is not improved.

[0060] Figure 5 shows that PCTFE, POM, PI, and PEEK, which have wear marks less than 6000 nm deep, are materials with excellent wear resistance. Furthermore, materials with shallower wear marks are preferable for the substrate holder 23, specifically materials with wear marks of 4000 nm or less are more preferable, and materials with wear marks of 2000 nm or less are even more preferable. In other words, based on the wear characteristic measurement results shown in Figure 5, samples E1 to E16 are judged to be suitable materials for the substrate holder 23.

[0061] Furthermore, considering the measurement results of the dynamic friction coefficient shown in Figure 4, it is determined that samples E1-E8, E11, E12, and E14-E16 are more suitable as materials for the substrate holder 23.

[0062] <Volatile Organic Compounds (VOC) gas release characteristics> From the samples in Table 1, the VOC emission characteristics were evaluated for sample E1 (PCTFE), sample E3 (Delrin® DRL-NA homopolymer POM), sample E7 (Duracon® NW-02LV copolymer POM), sample E8 (Sepra standard PI), sample E10 (Sepra G2 PI), sample E16 (ketron CA30 PEEK), and sample C3 (AS plate PE).

[0063] (Evaluation procedure) A test specimen measuring 50 mm (length) x 50 mm (width) x 5 mm (thickness) was placed in a baked, sealed stainless steel container, and the atmospheric gas inside the container was adsorbed and collected using a gas collection tube (TENAX-GR). Next, the gas collection tube was heated to desorb the adsorbed gas components, and the desorbed gas components were introduced into a GC / MS (Gas Chromatography Mass Spectrometry) analyzer to perform qualitative and quantitative analysis of organic components. The actual measurement method is shown below.

[0064] (Pre-processing) The sample surface was wiped with a methanol-soaked wipe and air-dried in a cleanroom for 4 hours. The sample was then heated using a GL Sciences MD2580M-B, and the gas generated from the sample was collected in a TENAX tube (at room temperature). The sample was heated from room temperature to 100°C over 25 minutes and held at 100°C for 300 minutes. The gas flow rate was 100 ml / min.

[0065] (measurement) Measurements were performed using thermal desorption-gas chromatography / mass spectrometry (TD-GC / MS). A GL Sciences TD2530 thermal desorption apparatus was used, an Agilent Technologies 7890B GC System gas chromatograph was used, and an Agilent Technologies 5977A mass spectrometer was used. I used MSD.

[0066] The measurements were taken under the following conditions. Collection tube desorption temperature: 270℃ GC introduction method: After cold trapping at -130°C, heating at 270°C. Column: InertCap 1MS (Length:60m, Diam:0.25mm, Film:0.25μm) Carrier gas: He Ionization method: EI method GC heating conditions: 40°C (held for 5 minutes) → heating at 10°C / min → 280°C (held for 21 minutes)

[0067] The released organic compound components were classified into three categories (1-3) based on their characteristics, and the detected amounts of each organic compound component were summarized. Organic compound components in category 1 are those that are released into the atmosphere due to their high volatility, or that are easily removed with ethanol because they are soluble in water and ethanol. Examples include toluene, styrene, octamethylcyclotetrasiloxane, benzyl alcohol, N,N'-diethylurea, dehydroacetic acid, butanone oxime, butyl acetate, ethylbenzene, xylene, propyl acetate, benzothiazole, phenol, glycerin, diethylene glycol monobutyl ether, hexane, methylcyclopentane, trioxane, diethylene glycol, 2-phenoxyethanol, caprolactam, 2-tert-butyl-p-cresol, diethylene glycol monobutyl ether acetate, hexanal, N-methylpyrrolidone, and tetraoxane.

[0068] The organic compound components in Class 2 are organic compound components that tend to adsorb and remain on the mask / blank substrate. Examples include pentadecanoic acid, hexadecenoic acid, heptadecanoic acid, oleic acid, stearic acid, squalene, and the alkane components decane, undecane, dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, and docosane.

[0069] Organic compound components in Class 3 are organic compound components that have a low vapor pressure and are poorly soluble in water and ethanol, and are therefore likely to remain in the substrate holder. Examples include dimethyl sebacate, diphenyl sulfone, dibutyl phthalate, 2,2,4,6,6-pentamethylheptane, 2,4-di-tert-butylphenol, butylhydroxytoluene, dodecanoic acid, diisobutyl adipate, 1-tetradecanol, tetradecanoic acid, palmitic acid, octane, dodecyl methacrylate, dimethyl glutarate, heptanal, octanal, nonanal, decanal, diethyl phthalate, 2-ethylhexanol, 1-hexadecene, 1-octadecene, hexadecyl acetate, and octadecyl acetate.

[0070] Tables 2 to 4 show the detection levels of each organic compound component in categories 1 to 3, respectively, while Table 5 shows the total detection level of organic compound components in categories 1 to 3. Figure 6 is a graph showing the total detection level of organic compound components in category 2 for each sample.

[0071] [Table 2]

[0072] [Table 3]

[0073] [Table 4]

[0074] [Table 5]

[0075] As shown in Table 5 and Figure 6, PCTFE (Sample E1) and PI Sepra standard (Sample E8) have extremely low total VOC levels, making them materials that are less likely to cause contamination of masks / blank substrates by chemical components.

[0076] While the total detected amount of VOCs in PI Sepra G2 (Sample E10), homopolymer POM Delrin® DRL-NA (Sample E3), copolymer POM Duracon® NW-02LV (Sample E7), and PEEK ketron CA30 (Sample E16) is relatively large, a breakdown reveals that most of these are organic compound components of categories 1 and 3. Category 1 components are organic compound components that are highly volatile and therefore released into the atmosphere, or that are easily soluble in water and ethanol and can be removed with ethanol, while Category 3 components are likely to remain in the holder, and are therefore considered unlikely to adversely affect the quality of the mask / blank substrate. Furthermore, the total amount of detected alkane components is preferably 20 μg or less. Moreover, the lower the total amount of detected alkane components, the better; more specifically, 5 μg or less is more preferable, and 2 μg or less is even more preferable.

[0077] The PE AS plate (sample C3) had a total of 103.4 μg of relatively large molecular weight alkane components, which is overwhelmingly higher than that of test specimens made of other materials. The individual alkane components actually detected were decane 15 μg, dodecane 24 μg, tridecane 6.6 μg, tetradecane 19 μg, pentadecane 3.1 μg, hexadecane 13 μg, heptadecane 4 μg, octadecane 9.4 μg, eicosane 6.4 μg, and heneicosane 2.9 μg.

[0078] If relatively large molecular weight alkane components volatilize and are released into the substrate housing case 1 from the substrate holder 23 installed in the lower box section 22 of the substrate housing case 1, and then adsorb onto the surface of the mask blank, serious problems may occur. Once these relatively large molecular weight alkane components adhere to the mask blank, their low vapor pressure makes it difficult for them to revolatilize from the mask blank, resulting in them remaining attached for a long time. Because alkane components are nonpolar, lipophilic components, the wettability of the resist differs significantly between areas on the mask blank where alkane components are attached and areas where they are not. As a result, unevenness occurs when the resist is applied, making it impossible to produce a photomask with the pattern structure specified in the design after the exposure, development, and wet etching processes.

[0079] Furthermore, in order to completely remove alkane components that have adhered to the mask blank, it is necessary to wash the mask blank multiple times using a strong acid such as sulfuric acid. It is known that light-shielding films and phase-shift films deposited on the mask blank are slightly dissolved by sulfuric acid washing, resulting in a reduction in film thickness. Therefore, especially with phase-shift films, the reduction in film thickness due to acid washing is accurately estimated, and mask blanks are shipped with the film thickness increased by that amount. However, if alkane components adhere to the mask blank, acid washing must be performed for a longer time and more times than usual to remove the alkane components, which can lead to the mask blank becoming thinner than the set film thickness, resulting in a photomask that does not have the desired optical properties after the process is completed.

[0080] Because of the problems described above, it is desirable to avoid, as much as possible, the adhesion of relatively large molecular weight alkane components to the surface of the mask blank. Therefore, PE AS plate is deemed unsuitable as a material for the substrate holder 23.

[0081] Based on the evaluation results of the VOC gas emission characteristics described above, PCTFE and PI (Sepra) are particularly excellent candidates as alternative materials to PTFE, which is commonly used in conventional substrate holders. PI (Sepra G2), homopolymer POM (Delrin® DRL-NA), copolymer POM (Duracon® NW-02), and PEEK (ketron CA30) are also deemed acceptable.

[0082] <Chemical resistance> The chemical resistance of each sample was evaluated, specifically its resistance to ethanol. Ethanol was used because it is typically used to clean the dedicated storage case and components such as the circuit board holders contained within the case. The test method involved using a cloth impregnated with 99.5% industrial ethyl alcohol to rub the surface of each test specimen 10 times back and forth at a speed of 1 second per back and forth stroke, after which the appearance of each test specimen was visually inspected.

[0083] No visible changes were observed in any of the samples E1-E16 and C1-C18. In other words, it was confirmed that the materials of samples E1-E16 and C1-C18 were not affected by ethanol.

[0084] Based on the results of the above tribological tests, evaluation of VOC emission characteristics, and chemical resistance tests, the material of the substrate holder 23 can be any of the following: polytrifluoroethylene chloride (PCTFE), polyimide (PI), polyacetal (POM), and polyetheretherketone (PEEK).

[0085] As described in detail above, according to this first embodiment, the substrate holder 23 is provided in the substrate housing case 1 that houses the mask / blank substrate 2, and is a substrate holder that holds the mask / blank substrate 2. The material of the substrate holder 23 is a material in which the wear depth of the test piece after a tribology test is performed on a test piece measuring 50 mm in length, 50 mm in width, and 5 mm in thickness with a 5 mm diameter SiO2 glass sphere at a load of 800 g, a rotation speed of 50 rpm, and a measurement time of 1 hour is 6000 nm or less. This makes it possible to suppress the generation of wear particles.

[0086] Furthermore, in this first embodiment, the material of the substrate holder 23 is such that the total amount of outgassed alkane compounds detected by a chromatographic mass spectrometer during the holding of a 50 mm x 50 mm x 5 mm test piece at 100°C for 300 minutes is 20 μg or less. This makes it possible to minimize the adhesion of relatively large molecular weight alkane components to the surface of the mask blank.

[0087] Furthermore, according to this first embodiment, the substrate holder 23 is provided in the substrate housing case 1 that houses the mask / blank substrate 2, and is a substrate holder that holds the mask / blank substrate 2. The material of the substrate holder 23 is one of polytrifluoroethylene chloride (PCTFE), polyimide (PI), polyacetal (POM), and polyetheretherketone (PEEK). This makes it possible to suppress the generation of wear particles.

[0088] (Examples) Using a substrate housing case equipped with a substrate holder according to the first embodiment, masks / blank substrates were actually transported, and the amount of dust detected on the masks / blank substrates was confirmed.

[0089] For the transport test, we used a dedicated inner case for G8 size photomask blanks made of polyacrylonitrile (PAN, Valex) manufactured by Net Plastic Co., Ltd. (model number BXAL-12141SSN8-N, equivalent to substrate housing case 1), and a dedicated outer case to house the inner case. The transport test was conducted as follows.

[0090] After installing one of the substrate holders from Examples 1-4 or Comparative Example 1 in the designated position inside the inner case, a G8-size quartz glass substrate was placed inside the inner case. At this time, the glass substrate was supported by the substrate holder. The inner case containing the glass substrate was placed inside the outer case and loaded onto the bed of a truck. With measures taken to prevent the outer case from tipping over, it was transported on public roads from Nikon Sagamihara Plant to Nikon Shonan Branch Office and back to Nikon Sagamihara Plant.

[0091] (Examples 1-4) In Example 1, the substrate holder 23 was made of homopolymer POM (Delrin® DRL-NA), in Example 2, the substrate holder 23 was made of PI (Sepra standard), in Example 3, the substrate holder 23 was made of copolymer POM (Duracon® NW-02), and in Example 4, the substrate holder 23 was made of PCTFE. The contact angles θ1 and θ2 at the corner holder 23a and the contact angles θ3 and θ4 at the edge holder 23b were 3° in all of Examples 1 to 4.

[0092] (Comparative Example 1) Comparative Example 1 used a PTFE holder. The contact angles θ1, θ2, θ3, and θ4 were 3°.

[0093] (Evaluation method) Using a large mask blank defect inspection system (LBIS, model L1052) manufactured by Lasertec Corporation, the total number of dust particles detected on the quartz glass substrate immediately before and after the transport test was counted, and the difference was calculated. Since the LBIS has a resolution of 0.3 μm, the total number of dust particles with a size of Φ0.3 μm or larger was counted.

[0094] Figure 7 shows the results of the transport test. In Figure 7, the vertical axis represents the increase in dust particles with a size of Φ0.3 μm or larger.

[0095] As shown in Figure 7, the inner case fitted with a PTFE holder (Comparative Example 1) showed an increase of 8,535 dust particles during the transport test. In contrast, the inner cases fitted with the substrate holders of Examples 1 to 4 showed lower increases in dust particles after the transport test, at 7,035, 5,897, 4,854, and 3,184 particles, respectively, compared to Comparative Example 1. In particular, Example 4 (PCTFE) showed a significant reduction in the amount of wear dust generated, to 1 / 2.7 of that of Comparative Example 1 (PTFE).

[0096] From the above results, it was confirmed that polytrifluoroethylene (PCTFE), polyimide (PI), polyacetal (POM), and polyetheretherketone (PEEK) are suitable materials for the substrate holder 23.

[0097] 《Second Embodiment》 Figure 8(A) is a cross-sectional view of the corner holder 123a according to the second embodiment, and Figure 8(B) is a cross-sectional view of the edge holder 123b according to the second embodiment. The corner holder 123a corresponds to the corner holder 23a in the first embodiment, and the edge holder 123b corresponds to the edge holder 23b in the first embodiment.

[0098] In the second embodiment, in the corner holder 123a, the holding surface (first holding surface) 124a1 is inclined with respect to a plane PL11 that is substantially parallel to the main surface (first main surface 2a) of the mask / blank substrate 2 held by the holding surface 124a1, and the contact angle θ11, which is the smaller of the angles made between the holding surface 124a1 and the plane PL11, is set to an angle of 4° or more and 45° or less. Furthermore, since the first member 123a1 and the second member 123a2 of the corner holder 123a have the same shape, the holding surface (second holding surface) 124a2 is inclined with respect to a plane PL12 that is substantially parallel to the main surface (second main surface 2b) of the mask / blank substrate 2 held by the holding surface 124a2, and the contact angle θ12, which is the smaller of the angles made between the holding surface 124a2 and the plane PL12, is also set to an angle of 4° or more and 45° or less.

[0099] In the edge holder 123b, the holding surface (first holding surface) 124b1 is inclined with respect to a plane PL13 that is substantially parallel to the main surface (first main surface 2a) of the mask / blank substrate 2, and the contact angle θ13, which is the smaller of the angles made between plane PL13 and the holding surface 124b1, is set to an angle of 4° to 45°. In addition, the holding surface (second holding surface) 124b2 is inclined with respect to a plane PL14 that is substantially parallel to the main surface (second main surface 2b) of the mask / blank substrate 2, and the contact angle θ14, which is the smaller of the angles made between plane PL14 and the holding surface 124b2, is set to an angle of 4° to 45°.

[0100] A simulation was conducted to determine the relationship between the contact angle θ between the holding surfaces 124 (holding surfaces 124a1 and 124a2, and holding surfaces 124b1 and 124b2) of the substrate holder 123 (corner holder 123a and edge holder 123b) and the mask / blank substrate 2, and the stress generated in the substrate holder 123. Figures 9(A) and 9(B) are cross-sectional views showing the model used in the simulation. In Figures 9(A) and 9(B), hatching indicating the cross-section is omitted. Note that in Figures 9(A) and 9(B), holding surfaces 124a1 and 124a2 are collectively referred to as holding surface 124a, and holding surfaces 124b1 and 124b2 are collectively referred to as holding surface 124b.

[0101] In Figure 9(A), consider the case where the mask / blank substrate 2 moves slightly in the X direction due to vibration during transport and is pressed against the substrate holder 123. In this case, the relative stress generated in the substrate holder 123 can be expressed as (1 / tanθ-μ)×aE / t. Here, μ represents the coefficient of dynamic friction, E represents the Young's modulus of the material of the substrate holder 123, a represents the long side of the contact surface between the mask / blank substrate 2 and the substrate holder 123, and t represents the thickness of the substrate holder 123.

[0102] On the other hand, consider the case in Figure 9(B) where the mask / blank substrate 2 moves slightly in the Z direction due to vibrations during transport and is pressed against the substrate holder 123. In this case, the relative stress generated in the substrate holder 123 can be expressed as (tanθ-μ)×aE / t.

[0103] It can be assumed that the higher the stress generated in the substrate holder 123, that is, the larger the index that relatively indicates the stress generated in the substrate holder 123, the more likely the substrate holder 123 is to wear down and generate wear particles.

[0104] Figure 10 is a graph showing the simulation results of an index that relatively indicates the stress generated in the substrate holder 123 with respect to the contact angle θ, when μ = 0.1. In Figure 10, the horizontal axis represents the contact angle θ, and the vertical axis represents the relative stress index generated in the substrate holder 123. Since aE / t is a fixed value, the relationship between the contact angle θ and the index that relatively indicates the stress generated in the substrate holder 123 was confirmed by setting aE / t = 1.

[0105] When the contact angle θ = 0°, the stress associated with the X-direction displacement is greatest, but the stress associated with the Z-direction displacement is greatest. On the other hand, when the contact angle θ = 90°, the stress associated with the X-direction displacement is greatest, but the stress associated with the Z-direction displacement is greatest. In other words, the stress associated with the X-direction displacement and the stress associated with the Z-direction displacement are inversely related.

[0106] In order to prevent the mask / blank substrate 2, which moves in the X and Z directions due to vibration, from falling off the support of the substrate holder 123, it is practically necessary to set the contact angle θ to 60° or less. Furthermore, since a clearance must be considered when supporting the mask / blank substrate 2 with the substrate holder 123, it is preferable to set the contact angle θ to 45° or less. Therefore, in the second embodiment, in order to support the mask / blank substrate 2 efficiently while reducing the amount of wear dust generated from the substrate holder, the contact angle θ was set to an angle within the range of 4° to 45°. From the viewpoint of reducing the amount of wear dust generated, the lower limit of the contact angle θ is more preferably 10°, and even more preferably 20°.

[0107] As described in detail above, according to the second embodiment, the corner holder 123a and the edge holder 123b are substrate holders provided in a substrate housing case 1 that houses the mask / blank substrate 2, and are substrate holders that hold the mask / blank substrate 2, with the corner holder 123a and the edge holder 123b each having holding surfaces 124a1 and 124b1 that contact the mask / blank substrate 2 and hold the mask / blank substrate 2. Furthermore, the smaller of the angles θ11 and θ12 between the holding surfaces 124a1 and 124b1 and the planes PL11 and PL12 which are substantially parallel to the main surface 2a or 2b of the mask / blank substrate 2 held by the holding surfaces 124a1 and 124b1 is 4° or more and 45° or less. This allows the stress generated in the corner holder 123a and the edge holder 123b to be kept within a range that suppresses the amount of wear dust generated, thereby reducing the amount of wear dust generated from the corner holder 123a and the edge holder 123b.

[0108] In the second embodiment described above, the first member 123b1 and the second member 123b2 of the edge holder 123b may be separate or integrally formed. When the first member 123b1 and the second member 123b2 are integrally formed, the entire edge holder 123b moves in a direction perpendicular to the edges of the opposing mask / blank substrate 2 (X direction or Y direction) in a plane substantially parallel to the main surface (first main surface 2a or second main surface 2b) of the mask / blank substrate 2. Furthermore, the first member 123b1 and the second member 123b2 may be in contact with each other or separated in the Z direction.

[0109] (Examples) Substrate holders 123 with different contact angles θ were fabricated, and mask / blank substrates were actually transported using substrate housing cases equipped with the fabricated substrate holders 123. The amount of dust detected on the mask / blank substrates was then confirmed. The inner and outer cases used in the transport test were the same as those in Examples 1-4 and Comparative Example 1. The method of conducting and evaluating the transport test was also the same as in Examples 1-4 and Comparative Example 1.

[0110] (Examples 5-10) In Example 5, the substrate holder 123 was made of PTFE, with the corner holder 123a having a contact angle θ11 of 5° and a contact angle θ12 of 17.5°, and the side holder 123b having a contact angle θ13 of 5° and a contact angle θ14 of 17.5°. In Example 6, the substrate holder 123 was made of PTFE, with the corner holder 123a having a contact angle θ11 of 12.5° and a contact angle θ12 of 17.5°, and the side holder 123b having a contact angle θ13 of 12.5° and a contact angle θ14 of 17.5°.

[0111] In Example 7, the substrate holder 123 was made of PCTFE, and the contact angles θ11 and θ12 of the corner holder 123a and the contact angles θ13 and θ14 of the edge holder 123b were set to 3°. In Example 8, the substrate holder 123 was made of PCTFE, and the contact angles θ11 of the corner holder 123a were set to 5° and θ12 to 17.5°, while the contact angles θ13 of the edge holder 123b were set to 5° and θ14 to 17.5°. In Example 9, the substrate holder 123 was made of PCTFE, and the contact angles θ11 of the corner holder 123a were set to 12.5° and θ12 to 17.5°, while the contact angles θ13 of the edge holder 123b were set to 12.5° and θ14 to 17.5°. In Example 10, the substrate holder 123 was made of PCTFE, and the contact angles θ11 and θ12 of the corner holder 123a and the contact angles θ13 and θ14 of the edge holder 123b were set to 45°.

[0112] (Comparative Example 2) As a comparative example 2, a substrate holder was prepared in which the material is PTFE and the contact angle between the holding surface of the substrate holder and the mask / blank substrate is 3°.

[0113] Figure 11 shows the results of the transport test. In Figure 11, the vertical axis represents the increase in dust particles with a size of Φ0.3 μm or larger.

[0114] Figure 11 shows that even with a substrate holder made of PTFE, which was deemed unsuitable as a substrate holder material in the first embodiment, the amount of dust generated after the transport test was significantly reduced by setting the contact angle to 5° or 12.5°. Therefore, it was confirmed that the generation of wear particles can be suppressed by setting the contact angle between the substrate holder and the mask / blank substrate to 5° or more.

[0115] Furthermore, it is even more preferable to set the contact angle between the substrate holder and the mask / blank substrate to 4° or more. The reason why a contact angle of 4° or more is preferable is as follows. The stress index, which is the vertical axis in Figure 10, is directly related to the amount of dust generated by transportation. From the results in Figure 10, it can be seen that between a contact angle of 3° and 10°, the stress index in the Z direction remains almost unchanged, while the stress index in the X direction changes significantly. Therefore, between a contact angle of 3° and 10°, the stress index in the X direction is dominant and has a large influence on dust generation. In other words, between a contact angle of 3° and 10°, the stress index in the X direction and the amount of dust are proportional.

[0116] Table 6 shows the results of the change in stress index for every 1° from 3° to 10°. Table 6 also shows that the stress index changes abruptly from 3° to 4°. From the results in Figure 10 and Table 6, the increase in dust particles at a contact angle of 3° (8535 particles) and at a contact angle of 5° (3587 particles) can be estimated to be around 5450 particles at a contact angle of 4°. Since the increase in dust particles is less than 6000 particles, it is considered that the increase in dust particles can be suppressed even at a contact angle of 4°. For this reason, it is preferable to set the contact angle to 4° or higher. [Table 6]

[0117] Furthermore, in the first embodiment, the PCTFE substrate holder, which was deemed suitable as the material for the substrate holder, was made with a contact angle of 5° or 12.5°, which was better than the case where the contact angle was 3°. It can be seen that the amount of dust increase after the transport test has decreased.

[0118] According to the stress simulation results shown in Figure 10, the stress decreases as the contact angle increases, so it is expected that the amount of dust increase will also decrease as the contact angle increases. In other words, it is expected that the amount of dust increase will be smallest when the contact angle is 45°. However, contrary to the simulation results shown in Figure 10, as shown in Figure 11, the amount of dust increase is large in the substrate holder with a contact angle of 45°. This is thought to be due to the following reasons.

[0119] In this transport test, a commercially available inner case was used, and only the substrate holder was replaced with the substrate holders from Examples 5 to 10. Increasing the contact angle while maintaining the thickness (mechanical strength) of the substrate holder requires increasing the overall length of the substrate holder in the design. However, due to space constraints imposed by the use of a commercially available inner case in this transport test, it was not possible to increase the overall length of the substrate holder. Therefore, in manufacturing substrate holders with a contact angle of 20° or more, it was necessary to reduce the thickness of the substrate holder. As a result, mechanical strength was sacrificed, and contrary to the simulation results shown in Figure 10, the amount of dust increased significantly in the substrate holder with a contact angle of 45°, as shown in Figure 11. Therefore, when using a commercially available inner case, the contact angle θ11 between the holding surface 124a1 and the mask / blank substrate 2 in the corner holder 123a is preferably between 4° and 20°. Furthermore, in the corner holder 123a, the contact angle θ12 between the holding surface 124a2 and the mask / blank substrate 2 is preferably between 4° and 20°. To suppress the increase in dust, the lower limit of the preferred contact angles θ11 and θ12 is more preferably 4.5°, and even more preferably 5°. Also, the upper limit of the contact angles θ11 and θ12 is more preferably 15°, and even more preferably 13°. Furthermore, when using a commercially available inner case, in the edge holder 123b, the contact angle θ13 between the holding surface 124b1 and the mask / blank substrate 2 is preferably between 4° and 20°. Furthermore, in the edge holder 123b, the contact angle θ14 between the holding surface 124b2 and the mask / blank substrate 2 is preferably between 4° and 20°. To suppress the increase in dust, the lower limit of the preferred contact angles θ13 and θ14 is more preferably 4.5°, and even more preferably 5°. Furthermore, the upper limits of the contact angles θ13 and θ14 are more preferably 15°, and even more preferably 13°.

[0120] Furthermore, these results indicate that when replacing only the circuit board holder in a commercially available inner case, using a circuit board holder with a contact angle in the range of 4° to 20° can sufficiently reduce the amount of wear dust generated.

[0121] Furthermore, if an inner case that allows for a longer overall length of the substrate holder is used instead of a commercially available inner case, it is considered that the amount of wear dust generated can be suppressed even if the contact angle is 45°. In that case, the lower limit values ​​of the contact angles θ11 and θ12 of the corner holder 123a are preferably 10° or more, and more preferably 20° or more. Similarly, the lower limit values ​​of the contact angles θ13 and θ14 of the edge holder 123b are preferably 10° or more, and more preferably 20° or more.

[0122] Furthermore, if an inner case is used that allows adjustment of the overall length of the substrate holder 123, the contact angles θ11 to θ14 of the substrate holder 123 may be set to 45° or more and 80° or less, as shown in the simulation results of Figure 10, in order to suppress the increase in dust. From the viewpoint of suppressing the increase in dust, the upper limit of the contact angles θ11 to θ14 may be 80° or less, more preferably 70° or less, and even more preferably 60° or less.

[0123] (modified version) In the first and second embodiments, the shapes of the edge holders 23b and 123b may be further modified. Figure 12 is a cross-sectional view showing an edge holder 223b according to a modified example. In Figure 12, the hatching indicating the cross-section is omitted.

[0124] In the first and second embodiments, when the mask / blank substrate 2 is placed on a plane parallel to planes PL1 to PL4, the edge r3 of the second connecting surface 2e and the holding surface of the second member are in contact. In contrast, in the modified example, as shown in Figure 12, when the mask / blank substrate 2 is placed on a plane parallel to planes PL1 to PL4, the holding surface (second holding surface) 224b2 of the second member 223b2 of the edge holder 223b is in contact with the lower edge r4 of the two edges r3 and r4 of the second connecting surface 2e.

[0125] Specifically, the smaller of the angles θ22 between the holding surface 224b2 and the plane PL23 which is substantially parallel to the main surface 2b of the mask / blank substrate 2 held by the holding surface 224b2 is an angle of 50° to 70°. This allows the holding surface 224b2 to be in contact with the edge portion r4, and even if dust is generated from the edge holder 223b, it is possible to suppress the adhesion of wear particles to the main surface 2b of the mask / blank substrate 2. Furthermore, the mask / blank substrate 2 can be held securely. In addition, it is possible to prevent the side surface 2c of the mask / blank substrate 2 from contacting the second member 223b2 and rubbing the side surface 2c. The contact angle θ22 is preferably an angle of 60° to 70°. This allows the holding surface 224b2 to be in contact with the edge portion r4 even when the chamfer angle of the second chamfered surface 2e of the mask / blank substrate 2 is large (50° or more).

[0126] In the modified example, the first member 223b1 and the second member 223b2 of the edge holder 223b may be separate or integrally formed. When the first member 223b1 and the second member 223b2 are integrally formed, the entire edge holder 223b moves in a direction (X direction or Y direction) perpendicular to the edges of the opposing mask / blank substrate 2, on a plane substantially parallel to the main surface (first main surface 2a or second main surface 2b) of the mask / blank substrate 2. The first member 223b1 and the second member 223b2 may be in contact with each other or separated in the Z direction.

[0127] The embodiments described above are preferred examples of the present invention. However, the invention is not limited thereto, and the first and second embodiments may be combined, and various modifications are possible without departing from the spirit of the invention. [Explanation of Symbols]

[0128] 1. Circuit board housing case 2 Mask / Blank PCB 23,123 Circuit board holder 23a,123a Corner holder 23a1, 123a1 First member 23a2,123a2 Second member 23b,123b,223b Side holder 23b1,123b1,223b1 First member 23b2,123b2,223b2 Second member 24a1,124a1 Holding surface (1st holding surface) 24a2,124a2 Holding surface (second holding surface) 24b1,124b1,224b1 Holding surface (1st holding surface) 24b2,124b2,224b2 Holding surface (second holding surface)

Claims

1. A substrate holder provided in a substrate housing case for housing a substrate having a first main surface, a second main surface opposite to the first main surface, a side surface substantially perpendicular to the first main surface, a first chamfered surface formed between the side surface and the first main surface, and a second chamfered surface formed between the side surface and the second main surface, A first member having a first retaining surface that contacts at least a portion of the first ridge line where the first chamfered surface and the first main surface intersect, A second member is provided that is movable in a plane substantially parallel to the second main surface relative to the first member, It has, The substrate holder has a second retaining surface that contacts at least a portion of a second ridge, which is either the ridge where the second main surface and the second chamfered surface intersect, or the ridge where the side surface and the second chamfered surface intersect.

2. The second ridge is the ridge where the second main surface and the second chamfered surface intersect. The substrate holder according to claim 1.

3. When the substrate housing case is positioned such that the first main surface of the housed substrate is substantially parallel to a horizontal plane perpendicular to the direction of gravity, the first angle, which is the smaller of the angles made between the first holding surface and the horizontal plane, is 4° or more and 45° or less, and the second angle, which is the smaller of the angles made between the second holding surface and the horizontal plane, is 4° or more and 45° or less. A substrate holder according to claim 1 or 2.

4. The first angle and the second angle are between 5° and 20°. The substrate holder according to claim 3.

5. The first angle and the second angle are the same angle. The substrate holder according to claim 3.

6. The second ridge is the ridge where the side surface and the second chamfered surface intersect. The substrate holder according to claim 1.

7. When the substrate housing case is positioned such that the first main surface of the housed substrate is substantially parallel to a horizontal plane perpendicular to the direction of gravity, the first angle, which is the smaller of the angles made between the first holding surface and the horizontal plane, is 4° or more and 45° or less, and the second angle, which is the smaller of the angles made between the second holding surface and the horizontal plane, is 50° or more and 70° or less. The substrate holder according to claim 6.

8. The second angle is between 60° and 70°. The substrate holder according to claim 7.

9. The material of the first and second holding surfaces is a test piece made of the material measuring 50 mm in length, 50 mm in width, and 5 mm in thickness, with a diameter of 5 mm of SiO₂ ２ The substrate holder according to claim 1 or claim 2, wherein the material is such that the wear depth of a test piece made of the material after a tribological test with a glass sphere, under a load of 800 g, a rotation speed of 50 rpm, and a measurement time of 1 hour, is 6000 nm or less.

10. The material of the first and second holding surfaces is such that the total amount of outgassed alkane compounds detected by a chromatographic mass spectrometer during the holding of a test specimen made of the material, measuring 50 mm in length, 50 mm in width, and 5 mm in thickness, at 100°C for 300 minutes is 20 μg or less. A substrate holder according to claim 1 or claim 2.

11. The alkane compound comprises at least one of decane, undecane, dodecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosane, heneicosane, and docosane. The substrate holder according to claim 10.

12. The material of the first retaining surface and the second retaining surface is one of the following: polytrifluoroethylene chloride (PCTFE), polyimide (PI), polyetheretherketone (PEEK), and copolymer-type polyacetal (copolymer-type POM). A substrate holder according to claim 1 or claim 2.

13. The substrate has another side adjacent to the aforementioned side, The aforementioned substrate holder is A third retaining surface that holds the substrate in contact with at least a portion of the first ridge corresponding to the other side, It has a fourth retaining surface that holds the substrate in contact with at least a portion of the second ridge corresponding to the other side, A substrate holder according to claim 1 or claim 2.

14. The substrate has another side adjacent to the side, The aforementioned substrate holder is A third member having a third retaining surface that contacts at least a portion of the first ridge portion corresponding to the other side, A fourth member is provided that is movable in a plane substantially parallel to the second main surface relative to the third member, It has, The fourth member has a fourth retaining surface that contacts at least a portion of the second ridge corresponding to the other side surface. A substrate holder according to claim 1 or claim 2.

15. The substrate is a photomask, a photomask blank, or a glass substrate before a thin film is deposited on the photomask blank. A substrate holder according to claim 1 or claim 2.

16. A substrate holder according to claim 1 or claim 2, Circuit board housing case.

17. The position adjustment unit is provided to move the position of the substrate holder in a direction substantially perpendicular to the side surface and adjust it to a position in contact with the substrate. A substrate housing case according to claim 16.

18. The substrate holder comprises a plurality of the aforementioned substrate holders. A substrate housing case according to claim 16.

19. The substrate has four sides, The multiple substrate holders are arranged so as to sandwich each of the two pairs of opposing sides. A substrate housing case according to claim 18.

20. The substrate holder is further positioned at a location corresponding to the corner of the substrate. The substrate housing case according to claim 19.

21. The substrate holder is further positioned at each of the four corners of the substrate. A substrate housing case according to claim 20.

22. It does not include members that contact the first main surface, the second main surface, and the four side surfaces. The substrate housing case according to claim 19.

23. A single substrate is housed in the above-mentioned substrate. A substrate housing case according to claim 16.

24. A substrate holding method comprising a substrate holder having a first main surface, a second main surface opposite to the first main surface, a side surface substantially perpendicular to the first main surface, a first chamfered surface formed between the side surface and the first main surface, and a second chamfered surface formed between the side surface and the second main surface, wherein the substrate is held by a substrate holder having a first member and a second member, The first retaining surface of the first member is held in contact with at least a portion of the first ridge line where the first chamfered surface and the first main surface intersect, With respect to the first member, the second member is moved in a plane substantially parallel to the second main surface, The second holding surface of the second member is held by contacting at least a portion of the second ridge line, which is either the ridge line where the second main surface and the second chamfered surface intersect, or the ridge line where the side surface and the second chamfered surface intersect. A substrate holding method including the following.

25. The second ridge is the ridge where the second main surface and the second chamfered surface intersect. The substrate holding method according to claim 24.

26. The second ridge is the ridge where the side surface and the second chamfered surface intersect. The substrate holding method according to claim 24.

27. A method for housing a substrate, comprising housing the substrate in a substrate housing case using the substrate holding method described in any one of claims 24 to 26.

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