Cleaning device, cleaning method, and manufacturing method of mask blank for euvl

Abstract

To provide a technology for suppressing surface roughness or film exfoliation on an undersurface of a substrate.SOLUTION: A cleaning device includes: a holding part which holds a substrate horizontally and includes a plurality of pins arranged at intervals along a periphery of the substrate; a rotation part which rotates the substrate with the holding part; a first nozzle which forms a liquid film of cleaning fluid on an upper surface of the substrate held by the holding part; and a second nozzle which supplies an inhibiting fluid for inhibiting etching of the substrate by the cleaning fluid to the pins. The second nozzle is fixed, and a ray of the second nozzle intersects a rotation track of the pin.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a cleaning device, a cleaning method, and a method for manufacturing a mask blank for EUVL.

Background Art

[0002] In recent years, with the miniaturization of semiconductor devices, extreme ultraviolet (EUV) lithography (EUVL), which is an exposure technique using extreme ultraviolet light (EUV), has been developed. EUV has a wavelength of about 13.5 nm. In EUVL, a reflective mask is used. The reflective mask has, in this order, a substrate such as a glass substrate, a multilayer reflective film that reflects EUV light, and an absorption film that absorbs EUV light. The absorption film may not only absorb EUV light but also shift the phase of EUV light. That is, the absorption film may be a phase shift film. An opening pattern is formed in the absorption film. In EUVL, the opening pattern of the absorption film is transferred onto a target substrate such as a semiconductor substrate. Transferring includes reducing and transferring.

[0003] The substrate processing apparatus described in Patent Document 1 spin-cleans a substrate. The step of spin-cleaning the substrate includes a step of supplying a cleaning liquid to the upper surface of the substrate while rotating the substrate, and a step of shaking off the cleaning liquid remaining on the upper surface of the substrate while rotating the substrate after stopping the supply of the cleaning liquid. The substrate is a semiconductor wafer, a glass substrate for a liquid crystal display device, a glass substrate for a plasma display panel, a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a magneto-optical disk, or a substrate for a photomask.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Conventionally, a cleaning device for spin-cleaning a substrate has been known. The cleaning device includes a holding part including a plurality of pins that horizontally hold the substrate, and a nozzle that forms a liquid film of a cleaning liquid on the upper surface of the substrate held by the holding part. Around the pins, the cleaning liquid tends to stay, and the cleaning liquid tends to flow around to the lower surface of the substrate. As a result, surface roughness or film peeling may occur on the lower surface of the substrate.

[0006] One aspect of the present disclosure provides a technique for suppressing surface roughness or film peeling on the lower surface of a substrate.

Means for Solving the Problems

[0007] A cleaning device according to one aspect of the present disclosure is a holding part that horizontally holds a substrate, the holding part including a plurality of pins arranged at intervals along the periphery of the substrate, a rotating part that rotates the substrate together with the holding part, a first nozzle that forms a liquid film of a cleaning liquid on the upper surface of the substrate held by the holding part, and a second nozzle that supplies a suppressing liquid for suppressing etching of the substrate by the cleaning liquid to the pins. The second nozzle is fixed, and the radiation of the second nozzle intersects the rotation orbit of the pins.

Effects of the Invention

[0008] According to one aspect of the present disclosure, since the radiation of the second nozzle intersects the rotation orbit of the pins, it is possible to suppress the retention of the cleaning liquid around the pins and to suppress the cleaning liquid from flowing around to the lower surface of the substrate. Therefore, it is possible to suppress surface roughness or film peeling on the lower surface of the substrate.

Brief Description of the Drawings

[0009]

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DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments for carrying out 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 the description thereof may be omitted. In the specification, "~" indicating a numerical range means that the numerical values described before and after it are included as the lower limit value and the upper limit value. The numerical range includes the rounded range.

[0011] With reference to FIGS. 1 to 5, a cleaning apparatus 1 according to an embodiment will be described. The cleaning apparatus 1 cleans the upper surface of the substrate W by rotating the horizontally held substrate W and supplying a cleaning liquid L1 to the upper surface of the substrate W (for example, the first main surface Wa). For example, particles attached to the substrate W can be removed.

[0012] The cleaning device 1 includes, for example, a holding unit 10, a rotating unit 20, and a first nozzle 30. The holding unit 10 holds the substrate W horizontally. The rotating unit 20 rotates the substrate W together with the holding unit 10. The first nozzle 30 forms a liquid film F1 of the cleaning liquid L1 on the upper surface of the substrate W held by the holding unit 10.

[0013] The holding unit 10 holds the substrate W horizontally. The substrate W includes a glass substrate, a silicon wafer, or a compound semiconductor wafer. The substrate W may include a functional film formed on, for example, a glass substrate. The functional film is, for example, a light reflection film, a light absorption film, a conductive film, or an insulating film. In this embodiment, the holding unit 10 holds one substrate W horizontally, but it may hold a plurality of substrates W horizontally.

[0014] The holding unit 10 includes, for example, as shown in FIG. 1, a plurality of pins 11 arranged at intervals along the periphery of the substrate W. The plurality of pins 11 hold the periphery of the substrate W. The substrate W is horizontally placed on the plurality of pins 11. The holding unit 10 has a rotating disk 12 to which the plurality of pins 11 are fixed. The plurality of pins 11 are erected on the upper surface of the rotating disk 12.

[0015] The rotating unit 20 rotates the substrate W together with the holding unit 10. The rotation center line 10R of the holding unit 10 is installed vertically. The rotation center line 10R is installed, for example, at the center of the upper surface of the substrate W. The rotating unit 20 includes, for example, a servo motor. The rotational driving force of the servo motor is transmitted to the holding unit 10 via a pulley and a belt (not shown) or gears.

[0016] The first nozzle 30 supplies the cleaning liquid L1 to the upper surface of the substrate W held by the holding unit 10. The cleaning liquid L1 is, for example, gas-dissolved water in which O3 gas or CO2 gas is dissolved, ammonia water, ammonia peroxide, sulfuric acid, sulfuric acid peroxide, peroxide, an alkaline detergent, an acid detergent, or hydrofluoric acid. The substrate W is rotating, and the cleaning liquid L1 spreads wet over the entire upper surface of the substrate W by centrifugal force to form a liquid film F1. The number of the first nozzles 30 may be one or more, and a plurality is also acceptable.

[0017] As shown in FIG. 2, the substrate W has a first main surface Wa and a second main surface Wb. The holding unit 10 holds the substrate W horizontally with the first main surface Wa or the second main surface Wb facing upward. The first main surface Wa and the second main surface Wb have a rectangular shape. In the present embodiment, the rectangle is a square with four equal sides, but it may have a pair of long sides and a pair of short sides. In this specification, the rectangle includes a shape with chamfers at the corners of the rectangle.

[0018] The substrate W has four end faces Wc along the four sides of the rectangle. The four end faces Wc are perpendicular to the first main surface Wa and the second main surface Wb. Further, the substrate W has four first chamfered surfaces Wd at the boundaries between the first main surface Wa and the four end faces Wc. Furthermore, the substrate W has four second chamfered surfaces We at the boundaries between the second main surface Wb and the four end faces Wc. The first chamfered surfaces Wd and the second chamfered surfaces We are planes inclined with respect to the first main surface Wa and the second main surface Wb, and are so-called C-chamfered surfaces.

[0019] As shown in FIG. 3, the pin 11 has a tapered surface 11a that tapers upward. The tapered surface 11a has a frustum of a cone shape. The tapered surface 11a of the pin 11 has a gentler inclination than the chamfered surface (for example, the second chamfered surface We) formed at the boundary between the lower surface (for example, the second main surface Wb) of the substrate W and the end face Wc. Therefore, the tapered surface 11a of the pin 11 contacts the boundary between the second main surface Wb and the second chamfered surface We.

[0020] A wedge-shaped gap G1 is formed between the lower surface (for example, the second main surface Wb) of the substrate W and the tapered surface 11a of the pin 11. Also, a wedge-shaped gap G2 is formed between the end face Wc of the substrate W and the tapered surface 11a of the pin 11. These gaps G1 and G2 are narrow. Therefore, these gaps G1 and G2 can cause the retention of the cleaning liquid L1 shown in FIG. 4, and consequently, surface roughness or film peeling on the lower surface of the substrate W.

[0021] Note that the structure of pin 11 is not particularly limited. For example, the tapered surface 11a may have the same inclination as the second chamfered surface We. In any case, around the pin 11, the cleaning liquid L1 tends to stay, and the cleaning liquid L1 also easily gets into the lower surface of the substrate W. Therefore, the pin 11 can cause surface roughness or film peeling on the lower surface of the substrate W.

[0022] As shown in FIG. 4, in order to suppress the cleaning liquid L1 from getting into the lower surface of the substrate W, it is also conceivable that a nozzle (not shown) supplies pure water or the like to the center of the lower surface of the substrate W. The pure water spreads wet over the entire lower surface of the substrate W by centrifugal force and is also supplied to the pin 11. However, since the pure water disperses and spreads radially on the lower surface of the substrate W, the flow rate of the pure water supplied to the pin 11 is smaller than the flow rate of the pure water discharged from the nozzle. Further, the gaps G1 and G2 are narrow, and the cleaning liquid that has entered the gaps G1 and G2 is difficult to be replaced by the pure water.

[0023] As shown in FIG. 5, in the present embodiment, a suppressing liquid L2 such as pure water is directly supplied to the pin 11. The suppressing liquid L2 suppresses the etching of the substrate W by the cleaning liquid L1. Therefore, surface roughness or film peeling on the lower surface of the substrate W can be suppressed. The suppressing liquid L2 is, for example, pure water, or gas-dissolved water in which N2 gas or H2 gas is dissolved. It is preferable to supply the suppressing liquid L2 to the pin 11 intermittently or continuously throughout the period of supplying the cleaning liquid L1 to the substrate W.

[0024] Next, with reference to FIGS. 5 and 1 again, an example of the second nozzle 40 will be described. The second nozzle 40 supplies the suppressing liquid L2 to the pin 11. As shown in FIG. 1, the second nozzle 40 is fixed, and the radiation 40A of the second nozzle 40 intersects the rotation orbit 11A of the pin 11. The radiation 40A of the second nozzle 40 is the center line of the flow of the suppressing liquid L2. While the first nozzle 30 supplies the cleaning liquid L1 to the substrate W, the rotating unit 20 rotates the substrate W together with the holding unit 10, and the second nozzle 40 intermittently supplies the suppressing liquid L2 to the pin 11.

[0025] As shown in FIG. 1, it is preferable that the plurality of pins 11 have the same rotation orbit 11A. One second nozzle 40 can intermittently supply the suppression liquid L2 to the plurality of pins 11. Although not shown, the plurality of pins 11 may have different rotation orbits. In that case, it is preferable that the cleaning device 1 includes the second nozzle 40 for each rotation orbit of the pins 11.

[0026] As shown in FIG. 1, it is preferable that the second nozzle 40 be arranged outside the rotation orbit 11A of the pin 11. The second nozzle 40 can be easily installed. Further, as shown in FIG. 5, it is preferable that the radiation 40A of the second nozzle 40 be obliquely downward. The suppression liquid L2 can be supplied to the pin 11 without going against gravity.

[0027] Although not shown, the second nozzle 40 may be arranged inside the rotation orbit 11A of the pin 11. In this case, a through hole is formed in the center of the turntable 12, and the second nozzle 40 is arranged in the through hole. In this case, as shown in FIG. 6, the radiation 40A of the second nozzle 40 is obliquely upward.

[0028] If the second nozzle 40 is arranged inside the rotation orbit 11A of the pin 11, the flow of the suppression liquid L2 can be formed outward. Therefore, it is possible to further suppress the cleaning liquid L1 from flowing around to the lower surface of the substrate W.

[0029] Next, with reference to FIGS. 7 and 8, another example of the second nozzle 40 will be described. As shown in FIG. 7, the second nozzle 40 may discharge the suppression liquid L2 from the inside to the outside of the pin 11. While the first nozzle 30 supplies the cleaning liquid L1 to the substrate W, the second nozzle 40 can continuously supply the suppression liquid L2 to the pin 11.

[0030] As shown in FIG. 7, the second nozzle 40 has a flow path 41 inside the pin 11. The outlet of the flow path 41, that is, the discharge port of the second nozzle 40, is preferably formed on the tapered surface 11a of the pin 11. The suppression liquid L2 can be supplied from the vicinity of the contact point between the pin 11 and the substrate W, and it is easy to supply the suppression liquid L2 to the wedge-shaped gaps G1 and G2.

[0031] As shown in FIG. 7, it is preferable that the second nozzle 40 discharges the suppression liquid L2 from above the contact point of the pin 11 with the substrate W. The suppression liquid L2 can flow from above to below along the pin 11 without going against gravity, and the suppression liquid L2 can be supplied to the wedge-shaped gaps G1 and G2.

[0032] As shown in FIG. 8, when looking at the holding part 10 from above, it is preferable that the radiation 40A of the second nozzle 40 has a component 40Aa directed toward the rotation center line 10R of the holding part 10. The suppression liquid L2 can be discharged against the centrifugal force, and the suppression liquid L2 can be sufficiently supplied to a location closer to the rotation center line 10R than the discharge port.

[0033] As shown in FIG. 8, when looking at the holding part 10 from above, it is more preferable that the radiation 40A of the second nozzle 40 is perpendicular to the end face Wc of the substrate W held by the holding part 10.

[0034] As shown in FIG. 1, the cleaning device 1 preferably includes a control unit 90. The control unit 90 is, for example, a computer and includes an arithmetic unit 91 such as a CPU (Central Processing Unit) and a storage unit 92 such as a memory. A program for controlling various processes executed in the cleaning device 1 is stored in the storage unit 92. The control unit 90 controls the operation of the cleaning device 1 by causing the arithmetic unit 91 to execute the program stored in the storage unit 92.

[0035] Next, with reference to FIG. 9, a method for manufacturing the EUVL mask blank 100 shown in FIG. 11 will be described. The method for manufacturing the EUVL mask blank 100 has steps S101 to S107. For example, a glass substrate 110 shown in FIG. 10 is prepared in advance.

[0036] The glass of the glass substrate 110 is preferably quartz glass containing TiO₂. Quartz glass has a smaller linear expansion coefficient and less dimensional change due to temperature change compared to general soda-lime glass. The quartz glass may contain 80% to 95% by mass of SiO₂ and 4% to 17% by mass of TiO₂. When the TiO₂ content is 4% to 17% by mass, the linear expansion coefficient near room temperature is approximately zero, and almost no dimensional change occurs near room temperature. The quartz glass may contain a third component or impurities other than SiO₂ and TiO₂.

[0037] The first main surface 110a and the second main surface 110b of the glass substrate 110 are, for example, rectangles with a length of 152 mm and a width of 152 mm. Note that the vertical dimension and the horizontal dimension are not particularly limited.

[0038] Step S101 includes polishing the first main surface 110a and the second main surface 110b of the glass substrate 110. In this embodiment, the first main surface 110a and the second main surface 110b are polished simultaneously with a double-sided polishing machine (not shown), but they may be polished sequentially with a single-sided polishing machine (not shown). In step S101, the glass substrate 110 is polished while supplying a polishing slurry between the polishing pad and the glass substrate 110.

[0039] As the polishing pad, for example, a urethane-based polishing pad, a non-woven fabric-based polishing pad, or a suede-based polishing pad is used. The polishing slurry includes an abrasive and a dispersion medium. The abrasive is, for example, cerium oxide particles. The dispersion medium is, for example, water or an organic solvent. The first main surface 110a and the second main surface 110b may be polished multiple times with abrasives of different materials or particle sizes.

[0040] Note that the abrasive used in step S101 is not limited to cerium oxide particles, and may be, for example, silicon oxide particles, aluminum oxide particles, zirconium oxide particles, titanium oxide particles, diamond particles, or silicon carbide particles.

[0041] Step S102 includes measuring the surface shapes of the first main surface 110a and the second main surface 110b of the glass substrate 110. For measuring the surface shapes, for example, a non-contact measuring instrument such as a laser interferometer is used so that the surface is not damaged.

[0042] Step S103 includes locally processing the first main surface 110a and the second main surface 110b of the glass substrate 110 with reference to the measurement results of Step S102 to improve flatness. The first main surface 110a and the second main surface 110b are locally processed in order. The order may be either first, and is not particularly limited.

[0043] For local processing, for example, at least one selected from a GCIB (Gas Cluster Ion Beam) method, a PCVM (Plasma Chemical Vaporization Machining) method, a polishing method using a magnetic fluid, and polishing using a rotary polishing tool is used.

[0044] Step S104 includes performing finish polishing on the first main surface 110a and the second main surface 110b of the glass substrate 110. In the present embodiment, the first main surface 110a and the second main surface 110b are polished simultaneously with a double-sided polishing machine (not shown), but may be polished in order with a single-sided polishing machine (not shown). In Step S104, the glass substrate 110 is polished while supplying a polishing slurry between the polishing pad and the glass substrate 110. The polishing slurry contains an abrasive. The abrasive is, for example, colloidal silica particles.

[0045] Step S105 includes forming a conductive film 140 shown in FIG. 11 on the second main surface 110b of the glass substrate 110. The conductive film 140 is used to adsorb the EUVL mask to the electrostatic chuck of the exposure apparatus. The conductive film 140 is formed of, for example, chromium nitride (CrN) or the like. As a film forming method of the conductive film 140, for example, a sputtering method is used.

[0046] Step S106 includes forming a multilayer reflective film 120 shown in FIG. 11 on the first main surface 110a of the glass substrate 110. The multilayer reflective film 120 reflects EUV. The multilayer reflective film 120 is, for example, formed by alternately laminating a high refractive index layer and a low refractive index layer. The high refractive index layer is formed of, for example, silicon (Si), and the low refractive index layer is formed of, for example, molybdenum (Mo). As a method for forming the multilayer reflective film 120, for example, a sputtering method such as an ion beam sputtering method or a magnetron sputtering method is used.

[0047] Step S107 includes forming an absorption film 130 shown in FIG. 11 on the multilayer reflective film 120 formed in step S106. The absorption film 130 absorbs EUV. The absorption film 130 may be a phase shift film and may shift the phase of EUV. The absorption film 130 is formed of, for example, a single metal, alloy, nitride, oxide, oxynitride, etc. containing at least one element selected from tantalum (Ta), chromium (Cr), ruthenium (Ru), iridium (Ir), and palladium (Pd). As a method for forming the absorption film 130, for example, a sputtering method is used.

[0048] Note that steps S106 to S107 are performed after step S105 in this embodiment, but may be performed before step S105.

[0049] By the above steps S101 to S107, the EUVL mask blank 100 shown in FIG. 11 is obtained. The EUVL mask blank 100 has a conductive film 140, a glass substrate 110, a multilayer reflective film 120, and an absorption film 130 in this order. Note that the EUVL mask blank 100 may include another film in addition to the conductive film 140, the glass substrate 110, the multilayer reflective film 120, and the absorption film 130.

[0050] For example, the EUVL mask blank 100 may further include a low-reflection film. The low-reflection film is formed on the absorption film 130. Then, an opening pattern 131 is formed in both the low-reflection film and the absorption film 130. The low-reflection film is used for inspecting the opening pattern 131 and has lower reflection characteristics than the absorption film 130 with respect to inspection light. The low-reflection film is formed of, for example, TaON or TaO. As a method for forming the low-reflection film, for example, a sputtering method is used.

[0051] Also, the EUVL mask blank 100 may further include a protective film. The protective film is formed between the multilayer reflection film 120 and the absorption film 130. The protective film protects the multilayer reflection film 120 so that the multilayer reflection film 120 is not etched when etching the absorption film 130 to form the opening pattern 131 in the absorption film 130. The protective film is formed of, for example, Ru, Si, Rh, or TiO2. As a method for forming the protective film, for example, a sputtering method is used.

[0052] As shown in FIG. 12, the EUVL mask 101 is obtained by forming an opening pattern 131 in the absorption film 130 of the EUVL mask blank 100. For forming the opening pattern 131, a photolithography method and an etching method are used. Accordingly, a resist film used for forming the opening pattern 131 may be included in the EUVL mask blank 100.

[0053] By the way, during the manufacturing process of the EUVL mask blank 100, the glass substrate 110 or various functional films formed on the glass substrate 110 may be cleaned. Cleaning using a chemical reaction with an acid or an alkali, cleaning using a physical action, or cleaning that is a combination of these may be performed. Cleaning using a physical action is ultrasonic cleaning, scrub cleaning, or two-fluid cleaning. Two-fluid cleaning sprays while mixing a cleaning liquid L1 and a gas.

[0054] The cleaning of the glass substrate 110 or the cleaning of various functional films formed on the glass substrate 110 is performed using, for example, the cleaning apparatus 1 shown in FIG. 1. The cleaning using the cleaning apparatus 1 is preferably carried out at least one of between step S104 and S105, between step S105 and S106, between step S106 and S107, and after step S107. Further, the cleaning using the cleaning apparatus 1 may be performed on the low-reflection film, the hard mask film, or the protective film.

[0055] As described above, the cleaning apparatus, the cleaning method, and the method for manufacturing a mask blank for EUVL according to the present disclosure have been described. However, the present disclosure is not limited to the above embodiments. Within the scope described in the claims, various changes, modifications, substitutions, additions, deletions, and combinations are possible. Naturally, those also belong to the technical scope of the present disclosure.

Explanation of Reference Numerals

[0056] 1 Cleaning apparatus 10 Holding part 11 Pin 20 Rotating part 30 First nozzle 40 Second nozzle L1 Cleaning liquid L2 Inhibiting liquid F1 Liquid film W Substrate

Claims

1. A holding part for holding a substrate horizontally, the holding part including a plurality of pins arranged at intervals along the periphery of the substrate; A rotating part for rotating the substrate together with the holding part; A first nozzle for forming a liquid film of a cleaning liquid on the upper surface of the substrate held by the holding part; A second nozzle for supplying a suppressing liquid for suppressing etching of the substrate by the cleaning liquid to the pins; Comprising; The second nozzle is fixed, and the radiation of the second nozzle intersects the rotation orbit of the pins, a cleaning device.

2. The plurality of pins have the same rotation orbit, the cleaning device according to Claim 1.

3. The second nozzle is arranged outside the rotation orbit of the pins, and the radiation of the second nozzle is obliquely downward, the cleaning device according to Claim 1.

4. The cleaning liquid is O ３ gas or CO ２ gas-dissolved water in which gas is dissolved, aqueous ammonia, ammonia peroxide, sulfuric acid, sulfuric acid peroxide, peroxide, an alkaline detergent, an acid detergent, or hydrofluoric acid, The inhibitory liquid is pure water or N ２ gas or H ２ The cleaning device according to claim 1, which is gas-dissolved water in which gas is dissolved

5. A holding part for holding a substrate horizontally, the holding part including a plurality of pins arranged at intervals along the periphery of the substrate; A rotating part for rotating the substrate together with the holding part; A first nozzle for forming a liquid film of a cleaning liquid on the upper surface of the substrate held by the holding part; A second nozzle for supplying a suppressing liquid for suppressing etching of the substrate by the cleaning liquid to the pins; Comprising; The second nozzle discharges the suppressing liquid from the inside to the outside of the pins, a cleaning device.

6. When looking at the holding part from above, the radiation of the second nozzle has a component directed toward the rotation center line of the holding part, the cleaning device according to Claim 5.

7. The second nozzle discharges the suppressing liquid from above the contact point of the pins with the substrate, the cleaning device according to Claim 5.

8. The cleaning liquid is O ３ gas or CO ２ gas-dissolved water in which gas is dissolved, aqueous ammonia, ammonia peroxide, sulfuric acid, sulfuric acid peroxide, peroxide, an alkaline detergent, an acid detergent, or hydrofluoric acid, The inhibitory liquid is pure water or N ２ gas or H ２ The cleaning device according to claim 5, which is gas-dissolved water in which gas is dissolved

9. A cleaning method including cleaning the substrate using the cleaning device according to any one of Claims 1 to 8.

10. A method for manufacturing an EUVL mask blank including cleaning a glass substrate or a functional film formed on the glass substrate using the cleaning device according to any one of Claims 1 to 8.

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