Glass plate processing method, processing device, and EUVL mask blank manufacturing method

Abstract

This processing method for glass substrates comprises: irradiating a first main surface of a glass substrate with a gas cluster in the form of a beam; moving the glass substrate so as to move the irradiation point of the gas cluster on the first main surface of the glass substrate; and using a shielding part that moves along with the glass substrate to block any anticipated fluid matter that would form defects on at least one of an end surface and a second main surface that faces the opposite direction of the first main surface of the glass substrate.

Description

[Technical Field]

[0001] The present disclosure relates to a glass plate processing method and processing apparatus, and a method for manufacturing an EUVL mask blank. [Background technology]

[0002] Photolithography has traditionally been used in the manufacture of semiconductor devices. In photolithography, an exposure apparatus irradiates a photomask pattern with light to transfer the photomask pattern onto a resist film.

[0003] Recently, in order to enable the transfer of fine patterns, the use of short wavelength exposure light, such as ArF excimer laser light or EUV (Extreme Ultra-Violet) light, has been considered.

[0004] Here, EUV light includes soft X-rays and vacuum ultraviolet light, and specifically refers to light with a wavelength of approximately 0.2 nm to 100 nm. At present, EUV light with a wavelength of approximately 13.5 nm is mainly being considered as exposure light.

[0005] Patent Document 1 describes a method for manufacturing a mask blank for EUVL (Extreme Ultra-Violet Lithography). The mask blank for EUVL includes a glass plate, a reflective film formed on the glass plate, and an absorbing film formed on the reflective film.

[0006] EUVL mask blanks require high flatness to improve the transfer accuracy of fine patterns. The flatness of EUVL mask blanks is determined primarily by the flatness of the glass plate that serves as the substrate, so high flatness is required of the glass plate.

[0007] The manufacturing method described in Patent Document 1 includes a preliminary polishing step, a measurement step, and a correction polishing step. In the preliminary polishing step, both main surfaces of a glass plate are pre-polished. In the measurement step, the maximum thickness distribution and flatness of the glass plate are measured. In the correction polishing step, the main surfaces of the glass plate are locally polished based on the measurement results of the measurement step. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2011 / 115131 Summary of the Invention [Problem to be solved by the invention]

[0009] The local polishing in Patent Document 1 uses gas clusters or the like. The gas clusters are ionized by the impact of thermal electrons, then accelerated by an electric field, and irradiated toward the first main surface of the glass plate, locally etching the first main surface. As a result, the first main surface can be flattened.

[0010] Gas clusters collide not only with the first main surface of the glass plate but also with peripheral components of the glass plate, which can cause defects on the second main surface of the glass plate facing away from the first main surface, or on one of the edge surfaces.

[0011] The defects are caused by, for example, flying debris, which can be gas clusters that have changed direction due to collision with a surrounding component, or particles that are ejected from a surrounding component due to collision between the gas cluster and the surrounding component. The material of the particles is the same as that of the surrounding component.

[0012] Defects can also occur due to direct collision of gas clusters. For example, if the first main surface of the glass plate is inclined with respect to the direction of irradiation of the gas clusters, the gas clusters will also directly collide with the edge surface of the glass plate.

[0013] Hereinafter, gas clusters, which are the cause of defects, and the scattered matter generated by the collision of gas clusters with surrounding parts will also be collectively referred to as fluid matter.

[0014] One aspect of the present disclosure provides a technique that can suppress the occurrence of defects in a glass sheet due to irradiation with gas clusters. [Means for solving the problem]

[0015] A method for processing a glass plate according to one embodiment of the present disclosure includes irradiating a beam of gas clusters onto a first main surface of the glass plate, moving the glass plate to move the irradiation point of the gas clusters on the first main surface of the glass plate, and blocking a fluid that is expected to form defects on at least one of a second main surface and an end surface of the glass plate facing opposite the first main surface with a shielding portion that moves together with the glass plate. [Effects of the Invention]

[0016] According to one aspect of the present disclosure, it is possible to suppress the occurrence of defects in a glass sheet due to irradiation with gas clusters. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a flowchart showing a method for manufacturing an EUVL mask blank according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing an example of a glass plate to be subjected to S1 in FIG. [Figure 3] FIG. 3 is a plan view showing an example of the glass plate of FIG. [Figure 4] FIG. 4 is a cross-sectional view showing an EUVL mask blank according to one embodiment. [Figure 5] FIG. 5 is a cross-sectional view showing an example of a photomask for EUVL. [Figure 6] FIG. 6 is a cross-sectional view showing a processing device according to one embodiment. [Figure 7] FIG. 7 is an enlarged cross-sectional view showing the glass plate, its peripheral components, and the shield plate of FIG. [Figure 8] FIG. 8 is a diagram showing the glass plate and its peripheral components as seen through the shield plate of FIG. 7 from the direction of irradiation of the gas clusters of FIG. [Figure 9] FIG. 9 is a view of the clamp and spacer of FIG. 7 from another direction. [Figure 10] FIG. 10 is a view of the stage according to the modified example, viewed from the direction of irradiation of the gas clusters. [Figure 11] FIG. 11 is a cross-sectional view showing a shielding portion according to a modified example. [Figure 12] FIG. 12 is a cross-sectional view showing a shielding portion according to another modified example. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a range of values means that the values before and after it are included as the lower and upper limits.

[0019] As shown in FIG. 1, the method for manufacturing a mask blank for EUVL (Extreme Ultra-Violet Lithography) includes steps S1 to S7. A glass plate is used to manufacture the mask blank. The glass of the glass plate is preferably quartz glass containing 90% or more by mass of SiO2. The upper limit of the SiO2 content in quartz glass is 100% by mass. Compared to general soda-lime glass, quartz glass has a smaller linear expansion coefficient and exhibits less dimensional change due to temperature changes. In addition to SiO2, quartz glass may contain TiO2. The quartz glass may contain 90% to 95% by mass of SiO2 and 5% to 10% by mass of TiO2. When the TiO2 content is 5% to 10% by mass, the linear expansion coefficient is approximately zero near room temperature, and there is almost no dimensional change near room temperature. The quartz glass may contain trace components other than SiO2 and TiO2, but it is preferable that it does not contain any trace components.

[0020] As shown in FIGS. 2 and 3 , the glass plate 2 includes a first main surface 21, a second main surface 22, four edge surfaces 23, four first chamfered surfaces 24, and four second chamfered surfaces 25. The first main surface 21 is rectangular. In this specification, a rectangular shape includes a shape with chamfered corners. A rectangle also includes a square. The second main surface 22 faces the opposite direction from the first main surface 21. Like the first main surface 21, the second main surface 22 is also rectangular. The edge surfaces 23 are perpendicular to the first main surface 21 and the second main surface 22. The first chamfered surface 24 is formed at the boundary between the first main surface 21 and the edge surfaces 23. The second chamfered surface 25 is formed at the boundary between the second main surface 22 and the edge surfaces 23. In this embodiment, the first chamfered surface 24 and the second chamfered surface 25 are so-called C-chamfered surfaces, but may also be R-chamfered surfaces.

[0021] The first main surface 21 of the glass plate 2 has a quality assurance region 26 shown by a dotted pattern in Fig. 3. The quality assurance region 26 is a region that is processed to a desired flatness by S1 to S4. The quality assurance region 26 is a region excluding a peripheral region 27 that is within a distance L of 5 mm from the edge surface 23 when viewed from a direction perpendicular to the first main surface 21. Although not shown, the second main surface 22 of the glass plate 2 also has a quality assurance region and a peripheral region, similar to the first main surface 21.

[0022] First, in S1 of FIG. 1, the first and second main surfaces 21 and 22 of the glass plate 2 are polished. The first and second main surfaces 21 and 22 may be polished simultaneously using a double-sided polisher, or may be polished sequentially using a single-sided polisher. In S1, the glass plate 2 is polished while a polishing slurry is supplied between the polishing pad and the glass plate 2. The polishing slurry contains an abrasive. The abrasive is, for example, cerium oxide particles. The first and second main surfaces 21 and 22 may be polished multiple times using abrasives of different materials or particle sizes.

[0023] The abrasive used in S1 is not limited to cerium oxide particles, but may be, for example, silicon oxide particles, aluminum oxide particles, zirconium oxide particles, titanium oxide particles, diamond particles, silicon carbide particles, or the like.

[0024] 1, the surface shapes of the first main surface 21 and the second main surface 22 of the glass plate 2 are measured. To measure the surface shapes, for example, a non-contact measuring machine such as a laser interference type is used to prevent the surface from being scratched. The measuring machine measures the surface shapes of the quality assurance area 26 of the first main surface 21 and the quality assurance area of the second main surface 22.

[0025] Next, in S3 of Fig. 1, the measurement result of S2 is referenced, and the first main surface 21 and the second main surface 22 of the glass plate 2 are processed with a beam-shaped gas cluster to improve flatness. The first main surface 21 and the second main surface 22 are etched in order with the gas cluster. The order in which they are etched may be either first or second, and is not particularly limited.

[0026] The gas clusters are ionized by the collision of the thermal electrons, then accelerated by an electric field, and after being neutralized, are irradiated toward the first main surface 21 or the second main surface 22. The collision of the gas clusters locally etches and flattens the first main surface 21 or the second main surface 22. Details of S3 will be described later.

[0027] Next, in S4 of FIG. 1, the first main surface 21 and the second main surface 22 of the glass plate 2 are subjected to finish polishing. The first main surface 21 and the second main surface 22 may be polished simultaneously using a double-sided polisher, or may be polished sequentially using a single-sided polisher. In S4, the glass plate 2 is polished while a polishing slurry is supplied between the polishing pad and the glass plate 2. The polishing slurry contains an abrasive. The abrasive is, for example, colloidal silica particles.

[0028] Next, in S5 of FIG. 1, a reflective film 3 shown in FIG. 4 is formed in the quality assurance area 26 of the first main surface 21 of the glass plate 2. The reflective film 3 reflects EUV light. The reflective film 3 may be, for example, a multilayer reflective film in which high-refractive-index layers and low-refractive-index layers are alternately stacked. The high-refractive-index layers are made of, for example, silicon (Si), and the low-refractive-index layers are made of, for example, molybdenum (Mo). The reflective film 3 is formed by sputtering, such as ion beam sputtering or magnetron sputtering.

[0029] Next, in S6 of FIG. 1, an absorbing film 4 shown in FIG. 4 is formed on the reflective film 3 formed in S5. The absorbing film 4 absorbs EUV light. The absorbing film 4 is formed of, for example, a single metal, alloy, nitride, oxide, or oxynitride containing at least one element selected from tantalum (Ta), chromium (Cr), and palladium (Pd). The absorbing film 4 is formed, for example, by sputtering.

[0030] Finally, in S7 of FIG. 1, a conductive film 5 shown in FIG. 4 is formed in the quality assurance area on the second main surface 22 of the glass plate 2. The conductive film 5 is used to electrostatically attract a photomask with an electrostatic chuck of an exposure tool. The conductive film 5 is formed of, for example, chromium nitride (CrN). The conductive film 5 is formed, for example, by sputtering. Note that, although S7 is performed after S5 and S6 in this embodiment, it may be performed before S5 and S6.

[0031] The positions of the reflective film 3 and the conductive film 5 may be reversed. That is, the conductive film 5 may be formed in the quality assurance area 26 of the first main surface 21 of the glass plate 2, and the reflective film 3 may be formed in the quality assurance area of the second main surface 22 of the glass plate 2. The absorbing film 4 is formed on the reflective film 3.

[0032] The above steps S1 to S7 result in the EUVL mask blank 1 shown in Fig. 4. The EUVL mask blank 1 includes a glass plate 2, a reflective film 3, an absorbing film 4, and a conductive film 5. The EUVL mask blank 1 does not necessarily include the conductive film 5. The EUVL mask blank 1 may also include another film.

[0033] For example, the EUVL mask blank 1 may further include a low-reflection film. The low-reflection film is formed on the absorbing film 4. The low-reflection film is used to inspect the opening pattern 41 of the absorbing film 4 shown in FIG. 5, and has lower reflectivity to inspection light than the absorbing film 4. The low-reflection film is made of, for example, TaON or TaO. The low-reflection film may be formed by, for example, sputtering.

[0034] The EUVL mask blank 1 may further include a protective film. The protective film is formed between the reflective film 3 and the absorbing film 4. The protective film protects the reflective film 3 so that the reflective film 3 is not etched when the absorbing film 4 is etched to form the opening pattern 41 in the absorbing film 4. The protective film is made of, for example, Ru, Si, or TiO2. The protective film may be formed by, for example, sputtering.

[0035] 5, the EUVL photomask is obtained by forming an opening pattern 41 in an absorbing film 4. Photolithography and etching are used to form the opening pattern 41. Therefore, the resist film used to form the opening pattern 41 may be included in the EUVL mask blank 1.

[0036] Next, a processing apparatus used in S3 of Fig. 1 will be described with reference to Fig. 6. The processing apparatus 100 is a so-called GCIB (Gas Cluster Ion Beam) processing apparatus.

[0037] The processing apparatus 100 includes a vacuum vessel 101. The vacuum vessel 101 has a nozzle chamber 102, an ionization / acceleration chamber 103, and a processing chamber 104. The three chambers 102, 103, and 104 are connected to each other to form a passage for gas clusters. The three chambers 102, 103, and 104 are evacuated by three vacuum pumps 105, 106, and 107, and maintained at a desired vacuum level. Note that the number of chambers and the number of vacuum pumps are not particularly limited.

[0038] The processing apparatus 100 includes a generation unit 110. The generation unit 110 generates gas clusters. The generation unit 110 includes, for example, a raw material tank 111, a pressure controller 113, a supply pipe 114, and a nozzle 116. The raw material tank 111 stores a raw material gas (e.g., CF4 gas). The pressure controller 113 controls the supply pressure of the raw material gas supplied from the raw material tank 111 to the nozzle 116 via the supply pipe 114. The nozzle 116 is provided in the nozzle chamber 102 and injects the raw material gas into a vacuum to form a supersonic gas jet 118.

[0039] The source gas is cooled by adiabatic expansion within the gas jet 118. As a result, a portion of the gas jet 118 condenses into gas clusters, each of which is an aggregate of several to several thousand atoms or molecules. Many gas clusters are found near the center of the flow of the gas jet 118. Therefore, by using the schema 119 to allow only the center of the flow of the gas jet 118 to pass, the gas clusters can be efficiently delivered.

[0040] The source gas is not limited to CF4 gas, and may be SF6 gas, Ar gas, O2 gas, N2 gas, NF3 gas, N2O gas, CHF3 gas, C2F6 gas, C3F8 gas, C4F6 gas, SiF4 gas, COF2 gas, SeF6 gas, TeF6 gas, or WF6 gas. A plurality of gases may be selected from these gases, or a mixed gas may be used as the source gas. The source gas is preferably one that can produce large-sized gas clusters and etch at a high rate, and specifically, one that contains fluorine.

[0041] The processing apparatus 100 includes an ionization section 120. The ionization section 120 ionizes at least a portion of the gas clusters in the gas jet 118. The ionization section 120 includes, for example, one or more hot filaments 124 and a cylindrical electrode 126. The hot filaments 124 receive power (voltage V F ) generates heat and emits thermoelectrons. The cylindrical electrode 126 accelerates the thermoelectrons emitted from the thermal filament 124 and causes the accelerated thermoelectrons to collide with gas clusters. The collision of the electrons with the gas clusters causes electrons to be emitted from some of the gas clusters, which then become positively ionized. Note that two or more electrons may be emitted, resulting in multiply charged ions. A voltage V from a power supply 127 is applied between the cylindrical electrode 126 and the thermal filament 124. A This voltage V A The thermal electrons are accelerated by the electric field and collide with the gas clusters.

[0042] The processing apparatus 100 includes an acceleration unit 130. The acceleration unit 130 accelerates the gas clusters ionized in the ionization unit 120 to form GCIBs 128. The acceleration unit 130 includes, for example, a first electrode 132 and a second electrode 134. The second electrode 134 is grounded, and a positive voltage Vs is applied to the first electrode 132 from a power supply 135. The first electrode 132 and the second electrode 134 form an electric field that accelerates the positively ionized gas clusters. The accelerated gas clusters are extracted as GCIBs 128 from an opening in the second electrode 134. The power supply 136 applies an acceleration voltage Vs that biases the ionization unit 120 relative to the first electrode 132 and the second electrode 134. Acc and the total GCIB accelerating potential is V Acc V Acc is, for example, 1 kV to 200 kV, preferably 1 kV to 70 kV.

[0043] The processing apparatus 100 may include a neutralization unit (not shown). The neutralization unit neutralizes the GCIBs 128 formed in the acceleration unit 130 to form neutral gas clusters. Since the glass plate 2 is irradiated with neutral gas clusters, it is possible to prevent the glass plate 2 from being charged. Note that even if the glass plate 2 is irradiated with positively ionized gas clusters, etching of the glass plate 2 is possible.

[0044] The processing apparatus 100 includes an irradiation unit 150. The irradiation unit 150 irradiates the glass plate 2 with a beam of gas clusters 129 to locally etch the glass plate 2. The diameter of the gas clusters 129 is, for example, 1 mm to 15 mm. The irradiation unit 150 includes, for example, a stage 151, a stage movement mechanism 152, and an aperture 153. The stage 151 is installed in the processing chamber 104 and holds the glass plate 2. The stage movement mechanism 152 moves the stage 151 two-dimensionally in the Y-axis and Z-axis directions to move the irradiation point of the gas clusters 129 on the glass plate 2. By controlling the movement speed, the etching amount can be controlled and the glass plate 2 can be flattened. The stage movement mechanism 152 can also move the stage 151 in the X-axis direction. The aperture 153 is provided midway along the path of the gas clusters 129 to improve the uniformity of the intensity of the gas clusters 129. The gas clusters 129 pass through the openings of the aperture 153 and are irradiated onto the glass plate 2 .

[0045] Next, the irradiation unit 150 of the processing apparatus 100 will be described with reference to Figures 7 to 9. In this specification, the X-axis direction, Y-axis direction, and Z-axis direction are perpendicular to each other. The X-axis direction and Y-axis direction are horizontal directions, and the Z-axis direction is vertical. In the following description, the positive X-axis direction is the forward direction, and the negative X-axis direction is the backward direction. The irradiation direction of the gas cluster 129 indicated by the arrow in Figure 7 is the positive X-axis direction.

[0046] As shown in Figure 7, the irradiation unit 150 irradiates beam-shaped gas clusters 129 forward, and the irradiated gas clusters 129 locally etch the first main surface 21 of the glass plate 2. The first main surface 21 is arranged facing backward and tilted obliquely upward. Because the first main surface 21 faces obliquely upward, the stage 151 can stably hold the glass plate 2 from below. Note that if the orientation of the glass plate 2 is reversed, local etching of the second main surface 22 of the glass plate 2 is also possible.

[0047] As shown in FIG. 9 , the stage 151 is disposed opposite the second main surface 22 of the glass plate 2. The stage 151 is disposed in front of the glass plate 2. The stage 151 may hold the glass plate 2 via, for example, a spacer 155. The spacer 155 forms a gap between the stage 151 and the glass plate 2. Compared to when the entire second main surface 22 of the glass plate 2 is in contact with the stage 151, the occurrence of contact scratches on the second main surface 22 can be suppressed.

[0048] The spacer 155 may have a tapered surface. If the tapered surface of the spacer 155 holds the second chamfered surface 25 of the glass plate 2, the spacer 155 will not come into contact with the second main surface 22 at all, thereby reliably preventing scratches on the second main surface 22. A part of the spacer 155 is disposed outside the glass plate 2 when viewed from the direction of irradiation of the gas cluster 129, as shown in FIG. 8.

[0049] In this embodiment, a part of the spacer 155 is disposed outside the glass plate 2 when viewed from the irradiation direction of the gas cluster 129, but it is also possible to dispose the entire spacer 155 inside the glass plate 2. In that case, the spacer 155 contacts not the second chamfered surface 25 of the glass plate 2 but the peripheral region of the second main surface 22 excluding the quality assurance region.

[0050] The stage 151 may also hold the glass plate 2 via clamps 156. This allows the glass plate 2 to be stably held in a vacuum. The entire clamps 156 are disposed outside the glass plate 2 when viewed from the direction of irradiation of the gas cluster 129. The clamps 156 press, for example, the edge surface 23 of the glass plate 2. A plurality of clamps 156 are provided at intervals along the periphery of the glass plate 2.

[0051] In this embodiment, the clamp 156 presses the edge surface 23 of the glass plate 2, but it may also press the peripheral region 27 of the first main surface 21 of the glass plate 2. The clamp 156 may also press the first chamfered surface 24 of the glass plate 2. In these cases, too, a part of the clamp 156 is disposed outside the glass plate 2 when viewed from the irradiation direction of the gas cluster 129.

[0052] The processing apparatus 100 includes peripheral components of the glass plate 2, such as a stage 151, a spacer 155, and a clamp 156. At least some of these peripheral components are disposed outside the glass plate 2 when viewed from the direction of irradiation of the gas clusters 129. Therefore, in the past, the gas clusters 129 could collide with these peripheral components, and the collision could cause defects on the edge surface 23 of the glass plate 2. Furthermore, when the spacer 155 forms a gap between the glass plate 2 and the stage 151, defects could also occur on the second main surface 22 of the glass plate 2.

[0053] Defects are caused by, for example, flying debris. Flying debris is gas clusters 129 that have changed direction due to collision with a surrounding component, or particles that fly out from the surrounding component due to collision between the gas clusters 129 and the surrounding component. The material of the particles is the same as the material of the surrounding component. Defects can include concave scratches or convex deposits. The scratches are the marks left by the collision of flying debris, and the deposits are the flying debris itself.

[0054] Defects can also occur due to direct collision of gas clusters 129. For example, if first main surface 21 of glass plate 2 is inclined with respect to the irradiation direction (X-axis direction) of gas clusters 129, gas clusters 129 will also directly collide with end surface 23 of glass plate 2. Hereinafter, gas clusters 129, which are the cause of defects, and debris generated by collision of gas clusters 129 with surrounding parts will also be collectively referred to as fluid matter.

[0055] As shown in FIG. 7, the irradiation unit 150 of this embodiment further includes a shielding unit 160. The shielding unit 160 moves together with the stage 151 and blocks the fluid that is expected to form defects on at least one of the second main surface 22 and the edge surface 23 of the glass plate 2. Blocking the fluid can suppress the occurrence of defects. If the defects on the second main surface 22 can be reduced, the time required for the subsequent finish polishing of the second main surface 22 can be shortened, resulting in a second main surface 22 with high flatness and few defects. This is because if the time for finish polishing is too long, the number of defects will be reduced but the flatness will deteriorate.

[0056] The shielding portion 160 includes, for example, a shield plate 161. The shield plate 161 is disposed opposite the first main surface 21 of the glass plate 2 and behind the glass plate 2. The shield plate 161 may not contact the glass plate 2, or a gap may be formed between the shield plate 161 and the glass plate 2. The shield plate 161 is formed in a frame shape as shown by the dashed line in FIG. 8 when viewed from the direction of irradiation of the gas clusters 129, and is disposed so as to overlap the entire periphery of the glass plate 2. The shield plate 161 blocks gas clusters 129 that directly impinge on the end surface 23 of the glass plate 2 before the collision, thereby reducing defects on the end surface 23. Furthermore, the shield plate 161 blocks gas clusters 129 that impinge on peripheral components before the collision, thereby reducing defects on the second main surface 22 and the end surface 23. When viewed from the direction of irradiation of the gas clusters 129, the spacers 155 and the clamps 156 are covered and hidden by the shield plate 161. Furthermore, when viewed from the irradiation direction of the gas clusters 129, a portion of the stage 151 that is outside the glass plate 2 and that is within a first predetermined distance from the periphery of the glass plate 2 is covered and hidden by a shield plate 161. The first predetermined distance is 125% of the distance from the first main surface 21 (rear surface) of the glass plate 2 to the rear surface of the stage 151.

[0057] The shield plate 161 is arranged outside the quality assurance area 26 so as not to overlap with the quality assurance area 26 of the first main surface 21 of the glass plate 2 when viewed from the irradiation direction of the gas clusters 129. This is to flatten the quality assurance area 26. The size of the opening 161a of the shield plate 161 is equal to or larger than the size of the quality assurance area 26 when viewed from the irradiation direction of the gas clusters 129.

[0058] Note that, in this embodiment, the shield plate 161 is formed in a frame shape when viewed from the direction of irradiation of the gas clusters 129, and is arranged so as to overlap the entire periphery of the glass plate 2, but the technology of the present disclosure is not limited to this. For example, a plurality of shield plates 161 may be arranged at intervals along the periphery of the glass plate 2 when viewed from the direction of irradiation of the gas clusters 129. It is sufficient that the occurrence of defects can be suppressed in at least a part of the periphery of the glass plate 2.

[0059] The material of the shield plate 161 may be any of metal, resin, and ceramic. However, when the gas clusters 129 collide with the shield plate 161, particles of the shield plate 161 may scatter onto the glass plate 2. Therefore, it is preferable that the material of the shield plate 161 is removable when the glass plate 2 is washed.

[0060] The cleaning of the glass plate 2 includes, for example, RCA cleaning. The RCA cleaning includes, for example, SC-1 cleaning, dilute hydrofluoric acid cleaning, and SC-2 cleaning, in this order. In SC-1 cleaning, a mixed aqueous solution of ammonium hydroxide (NH4OH) and hydrogen peroxide (H2O2) is used as the cleaning liquid. In dilute hydrofluoric acid cleaning, dilute hydrofluoric acid is used as the cleaning liquid. In SC-2 cleaning, a mixed aqueous solution of hydrochloric acid (HCl) and hydrogen peroxide is used as the cleaning liquid. The RCA cleaning may further include SPM cleaning. In SPM cleaning, a mixed aqueous solution of sulfuric acid (H2SO4) and hydrogen peroxide is used as the cleaning liquid.

[0061] The cleaning of the glass plate may include scrubbing, which involves scrubbing the glass plate with a brush or sponge. The scrubbing may be performed alone or as part of the RCA cleaning.

[0062] Aluminum, copper, iron, nickel, zinc, titanium, stainless steel, or brass is used as the metal material for the shield plate 161. These metals can be removed by RCA cleaning.

[0063] Examples of resins that can be used to make the shield plate 161 include vinyl acetate resin, ethylene-vinyl acetate copolymer resin, isobutene-maleic anhydride copolymer resin, acrylic copolymer resin, styrene-butadiene rubber copolymer, vinyl chloride resin, chloroprene rubber, nitrile rubber, epoxy resin, modified epoxy resin, silicone resin, modified silicone resin, urethane resin, EVA resin, ABS resin, polypropylene, high-density polyethylene, low-density polyethylene, polystyrene, polyester, polyamide, polyvinyl chloride, polycarbonate, PET (Poly Ethylene Terephthalate), POM (Poly Oxy Methylene), PBT (Poly Butylene Terephthalate), polyvinylidene chloride, PVA (Poly Vinyl Alcohol), and fluororesin. Furthermore, resins such as PPSU (Poly Phenyl Sulfone), PSU (Poly Sulfone), PAR (Poly Arylate), PEI (Poly Ether Imide), PEEK (Poly Ethel Ethel Keton), PPS (Poly Phenylene Sulfide), PES (Poly Ethel Sulfone), PAI (Poly Amide Imide), LCP (Liquid Crystal Polymer), PTFE (Poly Tetra Fluoro Ethylene), PCTFE (Poly Chloro TriFluoro Ethylene), or PVDF (Poly Vinylidene DiFluoride) are used as the material for the shield plate 161. These resins can be removed by RCA cleaning or scrubbing.

[0064] The ceramic material of shield plate 161 may be alumina, zirconia, aluminum nitride, silicon carbide, silicon nitride, forsterite, steatite, cordierite, sialon, machinable ceramic, barium titanate, lead zirconate titanate, ferrite, or mullite.

[0065] As described above, if the orientation of the glass plate 2 is reversed, it is naturally possible to locally etch the second main surface 22 of the glass plate 2. In this case, the shielding portion 160 moves together with the stage 151 and blocks the fluid that would otherwise form defects on at least one of the first main surface 21 and the edge surface 23 of the glass plate 2. Blocking the fluid can suppress the occurrence of defects. If the defects on the first main surface 21 can be reduced, the time required for the subsequent finish polishing of the first main surface 21 can be shortened, resulting in a first main surface 21 with high flatness and few defects. This is because if the finish polishing time is too long, the number of defects will be reduced but the flatness will deteriorate.

[0066] Next, a stage 151 according to a modified example will be described with reference to Fig. 10. As described above, the stage 151 is disposed opposite the second main surface 22 of the glass plate 2. The stage 151 is disposed in front of the glass plate 2.

[0067] Stage 151 includes opening 151a through which gas clusters 129 pass. Opening 151a is arranged to overlap the periphery of glass plate 2 when viewed from the irradiation direction of gas clusters 129, as shown in Fig. 10. Collisions between gas clusters 129 and stage 151 near the periphery of glass plate 2 can be suppressed, and defects caused by such collisions can be suppressed.

[0068] A plurality of openings 151a in the stage 151 may be formed at intervals along the periphery of the glass plate 2. The openings 151a may be disposed between adjacent spacers 155 and clamps 156, or between two adjacent clamps 156.

[0069] Incidentally, at least a portion of the spacers 155 and the clamps 156 is disposed outside the glass plate 2 when viewed from the irradiation direction of the gas clusters 129. Therefore, the gas clusters 129 may also collide with the spacers 155 and the clamps 156.

[0070] Therefore, the stage 151 of this modification may be used in combination with the shield plate 161 of the above embodiment. When viewed from the direction of irradiation of the gas cluster 129, the spacer 155 and the clamp 156 may be covered and hidden by the shield plate 161.

[0071] In this case, a plurality of shield plates 161 may be arranged at intervals along the periphery of glass plate 2 as viewed from the irradiation direction of gas clusters 129. As viewed from the irradiation direction of gas clusters 129, openings 151a of stage 151 are arranged between adjacent shield plates 161.

[0072] Next, a shielding portion 160 according to a modified example will be described with reference to Fig. 11. The shielding portion 160 may include a mask 162 that covers the second main surface 22 of the glass plate 2, and a mask 163 that covers the end surface 23 of the glass plate 2. Note that the shielding portion 160 only needs to include at least one of the two masks 162, 163.

[0073] The mask 162 covers the second main surface 22 of the glass plate 2 and blocks a fluid that would otherwise cause defects on the second main surface 22 before it collides with the second main surface 22. This prevents defects from occurring on the second main surface 22. In this modification, the mask 162 covers the entire second main surface 22, but it is sufficient to cover at least a portion within a second predetermined distance from the end surface 23. The second predetermined distance is 200% of the gap between the stage 151 and the glass plate 2 formed by the spacer 155, or in other words, 200% of the distance from the second main surface 22 (front surface) of the glass plate 2 to the rear surface of the stage 151.

[0074] Furthermore, the mask 163 covers the edge surface 23 of the glass plate 2, and blocks the fluid that would otherwise cause defects on the edge surface 23 before it collides with the edge surface 23. This makes it possible to suppress the occurrence of defects on the edge surface 23. In this modification, the mask 163 covers the edge surface 23 over the entire periphery of the glass plate 2, but it is sufficient if the edge surface 23 is covered over at least a portion of the periphery of the glass plate 2.

[0075] The masks 162 and 163 are preferably made of a material that can be removed when cleaning the glass plate 2. The cleaning of the glass plate 2 is, for example, RCA cleaning. Scrub cleaning may also be used. Scrub cleaning may be used alone or as part of RCA cleaning. The masks 162 and 163 may be single-layered or multi-layered.

[0076] The masks 162, 163 preferably include a resin layer as a layer that comes into contact with the glass plate 2. The resin layer may be a single layer or multiple layers. The resin layer does not contain filler or powder at least on the surface that comes into contact with the glass plate 2. This is because filler and powder can cause dust generation or scratches. The resin layer preferably does not contain filler or powder not only on the surface that comes into contact with the glass plate 2 but also inside.

[0077] The resin layer can be easily removed by scrubbing. In scrubbing, the resin layer is scrubbed with a brush or sponge. In scrubbing, an alkaline solution containing a surfactant may be used as the cleaning liquid. The effect of the alkali can improve removal efficiency. Scrub cleaning and ultrasonic cleaning may be used in combination.

[0078] The masks 162 and 163 of this modification may be used in combination with the shield plate 161 of the above embodiment or the stage 151 of the above modification.

[0079] Next, a shielding section 160 according to another modification will be described with reference to Fig. 12. The shielding section 160 includes a mask 163 that covers the edge surface 23 of the glass plate 2. This mask 163 also closes the gap between the glass plate 2 and the stage 151, thereby suppressing the occurrence of defects on the second main surface 22. According to this modification, the mask 162 shown in Fig. 12 is not necessary, and therefore removal of the mask 162 is not necessary, making it easy to clean the glass plate 2.

[0080] The mask 163 of this modification may be used in combination with the shield plate 161 of the above embodiment or the stage 151 of the above modification. [Example]

[0081] The experimental data will be explained below. Examples 1 and 2 below are working examples, and Example 3 is a comparative example.

[0082] In Example 1, the first main surface 21 of the glass plate 2 was processed with a beam-like gas cluster 129 by the processing apparatus 100 shown in Fig. 6. The processing conditions were as follows. Material of glass plate 2: quartz glass containing TiO2 Source gas: CF4 gas Acceleration voltage V Acc :60kV Stage 151 material: Aluminum Shape of stage 151: Shape of Figure 10 Shield plate 161 material: Aluminum Shape of shield plate 161: Shape shown in FIG. 8 Masks 162 and 163: None.

[0083] In Example 1, the shield plate 161 was used to prevent the gas clusters 129 from colliding with the stage 151, which is a peripheral component of the glass plate 2. As a result, no adhesion of aluminum particles (particles that fly off the stage 151 due to the collision of the gas clusters 129) was visually confirmed on the second main surface 22 and the end surface 23 of the glass plate 2.

[0084] In Example 2, the first main surface 21 of the glass plate 2 was processed with the beam-shaped gas cluster 129 under the same processing conditions as in Example 1, except that the shield plate 161 was not used. In Example 2, when viewed from the irradiation direction of the gas cluster 129, in the region where the opening 151a of the stage 151 and the periphery of the glass plate 2 overlap, no adhesion of aluminum particles was visually confirmed on the second main surface 22 and the end face 23 of the glass plate 2. However, when viewed from the irradiation direction of the gas cluster 129, in the region where the opening 151a of the stage 151 and the periphery of the glass plate 2 do not overlap, slight adhesion of aluminum particles was visually confirmed on the second main surface 22 and the end face 23 of the glass plate 2.

[0085] In Example 3, the first main surface 21 of the glass plate 2 was processed with the beam-like gas cluster 129 under the same processing conditions as in Example 1, except that the shield plate 161 was not used and a stage 151 without the opening 151a was used. In Example 3, adhesion of aluminum particles was visually confirmed on the second main surface 22 and the end surface 23 of the glass plate 2 all over the periphery of the glass plate 2.

[0086] The results of Examples 1 to 3 show that using shield plate 161 or forming openings 151a in stage 151 can suppress adhesion of aluminum particles (particles that fly out of stage 151 due to collision with gas clusters 129).

[0087] The glass plate processing method, processing apparatus, and EUVL mask blank manufacturing method according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0088] For example, the use of the glass plate processed by the processing method and processing apparatus of the present disclosure is not limited to EUVL. The use of the glass plate may be any use that requires high flatness, such as a medical device. Furthermore, the glass composition of the glass plate may be any use that corresponds to the use of the glass plate.

[0089] This application claims priority based on Japanese Patent Application No. 2020-084728, filed with the Japan Patent Office on May 13, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0090] 1. Mask blanks for EUVL 2 glass plates 21 First main surface 22 Second main surface 23 End face 3 Reflective film 4. Absorbent membrane 100 Processing equipment 129 Gas Cluster 150 Irradiation unit 151 Stages 151a aperture 152 Stage movement mechanism 155 Spacer 156 Clamp 160 Shielding part 161 Shield plate 162, 163 Mask

Claims

1. irradiating a first main surface of the glass plate with a beam of gas clusters; moving the glass plate to move an irradiation point of the gas cluster on the first main surface of the glass plate; and blocking a fluid that is intended to form defects on at least one of a second main surface of the glass plate facing away from the first main surface and an end surface of the glass plate by a blocking unit that moves together with the glass plate, at least a part of peripheral components of the glass plate is disposed on the outer side of the glass plate as viewed from the irradiation direction of the gas clusters; the shielding portion includes a shield plate disposed opposite the first main surface of the glass plate, The shield plate covers and conceals at least a part of the peripheral components arranged outside the glass plate when viewed from the direction of irradiation of the gas clusters.

2. The processing method described in claim 1, wherein the peripheral parts include at least one of a stage, a spacer, and a clamp.

3. A processing method as described in claim 1 or 2, wherein the shield plate is positioned so as to overlap the periphery of the glass plate when viewed from the direction of irradiation of the gas cluster.

4. 4. The processing method according to claim 3, wherein the shield plate is formed in a frame shape and is arranged so as to overlap the entire periphery of the glass plate when viewed from the direction of irradiation of the gas clusters.

5. The processing method according to any one of claims 1 to 4, wherein the shielding portion includes at least one of a mask covering the second main surface of the glass plate and a mask covering the end surface of the glass plate.

6. a stage for holding the glass plate is disposed opposite the second main surface of the glass plate and holds the glass plate via a spacer; The processing method according to any one of claims 1 to 5, wherein the spacer forms a gap between the glass plate and the stage.

7. The processing method according to claim 6 , wherein a part of the spacer is disposed outside the glass plate when viewed from the direction of irradiation of the gas clusters.

8. a stage for holding the glass plate is disposed opposite the second main surface of the glass plate and holds the glass plate via a clamp; 8. The processing method according to claim 1, wherein at least a part of the clamp is disposed outside the glass plate when viewed from the direction of irradiation of the gas clusters.

9. a stage for holding the glass plate is disposed opposite the second main surface of the glass plate and includes an opening for allowing the gas cluster to pass therethrough; 9. The processing method according to claim 1, wherein the opening of the stage is arranged so as to overlap the periphery of the glass plate when viewed from the direction of irradiation of the gas clusters.

10. irradiating a first main surface of the glass plate with a beam of gas clusters; moving the glass plate to move an irradiation point of the gas cluster on the first main surface of the glass plate; a stage for holding the glass plate is disposed to face a second main surface of the glass plate facing away from the first main surface, and includes an opening for allowing the gas cluster to pass therethrough; The processing method, wherein the opening of the stage is positioned so as to overlap the periphery of the glass plate when viewed from the direction of irradiation of the gas clusters.

11. flattening the first main surface of the glass plate using the processing method according to any one of claims 1 to 10; forming a reflective film that reflects EUV light on the first main surface of the glass plate; forming an absorbing film that absorbs EUV light on the reflective film; A method for manufacturing an EUVL mask blank, comprising:

12. an irradiation unit that irradiates a beam of gas clusters onto a first main surface of the glass plate; The irradiation unit is a stage for holding the glass plate; a stage moving mechanism that moves the stage so as to move an irradiation point of the gas cluster on the first main surface of the glass plate; a shielding portion that moves together with the stage and blocks a fluid that is intended to form defects on at least one of a second main surface of the glass plate facing away from the first main surface and an end surface, at least a part of peripheral components of the glass plate is disposed on the outer side of the glass plate as viewed from the irradiation direction of the gas clusters; the shielding portion includes a shield plate disposed opposite the first main surface of the glass plate, The shield plate covers and conceals at least a part of the peripheral components arranged outside the glass plate when viewed from the direction of irradiation of the gas clusters.

13. The processing apparatus described in Claim 12, wherein the peripheral parts include at least one of a stage, a spacer, and a clamp.

14. an irradiation unit that irradiates a beam of gas clusters onto a first main surface of the glass plate; The irradiation unit is a stage for holding the glass plate; a stage moving mechanism that moves the stage so as to move an irradiation point of the gas cluster on the first main surface of the glass plate, the stage is disposed to face a second main surface of the glass plate facing away from the first main surface, and includes an opening through which the gas cluster passes; The processing apparatus is configured such that the opening of the stage overlaps with the periphery of the glass plate when viewed from the direction of irradiation of the gas clusters.

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