JP2004310068A - Apparatus for removing unnecessary film and method of manufacturing mask blank - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems that, when an unnecessary part of a film formed on a substrate is to be removed, a residue of the unnecessary film is generated in the part of the substrate where the unnecessary film is removed or a recess or a pinhole defect is produced in a pattern forming region. <P>SOLUTION: The apparatus for removing an unnecessary film functions to supply a chemical liquid which can dissolve the film, to the unnecessary part of the film formed on a substrate 1 through a cover member 13 having a chemical liquid supply passage 13a to supply the chemical liquid and to dissolve and remove the film in the aimed part. The apparatus has a constitution equipped with: a chemical liquid supply means 14 to supply the chemical liquid to the chemical liquid supply passage; a chemical liquid supply controlling means to control to start and stop supplying the chemical liquid; and a fluid supply means 15 to supply a gas or a liquid insoluble with the film to the chemical liquid supply passage so as to discharge the chemical liquid remaining in the chemical liquid supply passage after supplying the chemical liquid to the liquid supply passage is stopped. This invention is effective when applied for the manufacturing method of a mask blank, and further, it can be used for removing an unnecessary part of a protective film formed on an information recording medium, a color filter or the like, or for removing an unnecessary part of an insulating film formed in an electrode in the wiring on a display substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an unnecessary film removing apparatus for removing an unnecessary portion of a film formed on a substrate such as a photomask blank (hereinafter, referred to as a mask blank), a semiconductor substrate, an information recording medium, and a color filter, and a method for manufacturing a mask blank. .

  In the manufacture of mask blanks, semiconductor substrates, information recording media, color filters, etc., when forming a film on a substrate, a film may be formed on an unnecessary portion such as a peripheral portion of the substrate. It is required to be removed.

  For example, a film such as a resist film, a resist base anti-reflective coating (BARC: Bottom Anti-Reflective Coating), a resist upper layer anti-reflective film (TARL: Top Anti-Reflective Layer 9), and a resist upper layer protective film are formed on a substrate. Is formed by a spin coating method or the like, the coating liquid is collected at the peripheral portion of the substrate (including the side surface of the substrate and the back surface of the substrate), and a relatively thick resist film is formed thereon. You.

  The resist film formed on the peripheral edge of the substrate in this manner is liable to peel off or fall off when handling the substrate, which not only causes a defect of the product but also causes a problem when supporting the substrate in a later process. It can be a hindrance. Therefore, there has been proposed a method for removing an unnecessary portion formed on a peripheral portion of a substrate from a resist film formed on the substrate (for example, see Patent Document 1).

  The unnecessary film removing method disclosed in Patent Literature 1 covers a substrate on which a resist film is formed with a cover member having a large number of chemical solution supply holes formed on a peripheral edge thereof, while rotating the substrate and the cover member integrally. By supplying a chemical solution to the peripheral portion of the substrate through a chemical solution supply hole of the cover member, an unnecessary portion of the resist film is dissolved and removed.

When the unnecessary portion of the resist film is removed by using the above-described unnecessary film removing method, a chemical solution is supplied to the peripheral portion of the substrate while rotating the substrate and the cover member at a predetermined rotation frequency f1, and the unnecessary portion is removed. The dissolving process P1 for dissolving the film and the supply of the chemical solution are stopped, and the unnecessary film that has been dissolved is removed by centrifugal force to the outside of the substrate while rotating the substrate and the cover member at a predetermined rotation speed f2 (f2> f1). In addition, it is preferable to perform a removal / drying step P2 of drying an unnecessary film removed portion of the substrate.
JP-A-2001-259502 (page 6, FIG. 1)

However, in a substrate manufactured by using the above-described unnecessary film removing method, there is a problem that a residue of a resist film is present at a peripheral portion or a concave or pinhole-like defect occurs in a pattern forming region of the resist film. .
The resist residue was generated because the unnecessary film dissolved in the above-described dissolving step P1 was not reliably removed in the removing / drying step P2. When the resist residue adhered to the pattern formation region of the resist film, This may cause a substrate defect.
In addition, the concave or pinhole-shaped defect is generated when the chemical liquid accumulated in the chemical liquid supply hole of the cover member falls into the pattern formation region of the resist film when the cover member is removed from above the substrate. The substrate on which such a defect has occurred is immediately eliminated as a defective product, thus lowering the yield.

  The present invention has been made in consideration of the above circumstances, and in removing an unnecessary portion of a film formed on a substrate, unnecessary film residues are generated in an unnecessary film removed portion of the substrate, and a film in a pattern formation region is removed. It is an object of the present invention to provide an unnecessary film removing apparatus, an unnecessary film removing method, and a method of manufacturing a mask blank, which can solve the problem that a concave or pinhole-like defect occurs in the substrate and can improve the yield in removing the unnecessary film. .

In order to achieve the above object, the unnecessary film removing apparatus of the present invention is provided through a cover member provided with a chemical solution supply path for supplying a chemical solution capable of dissolving the film to an unnecessary portion of the film formed on the substrate. An unnecessary film removing device that supplies a chemical solution and dissolves and removes a film in this portion, and a chemical solution supply unit that supplies a chemical solution to the chemical solution supply path, and a chemical solution supply control unit that controls start and stop of supply of the chemical solution. And a fluid supply means for supplying a fluid to the chemical solution supply path in order to discharge the chemical solution remaining in the chemical solution supply path after stopping the supply of the chemical solution to the chemical solution supply path.
With this configuration of the unnecessary film removing device, it is possible to reliably remove the residue of the unnecessary film by providing the fluid supply unit that discharges the chemical solution remaining in the chemical solution supply path. The fluid used for the fluid supply means only needs to be insoluble in the film formed on the substrate, and may be a liquid or a gas.
Also, after removing the unnecessary film, by supplying unnecessary liquid to the film to the chemical liquid supply path, the chemical liquid remaining in the chemical liquid supply path can be removed, so when removing the cover member from above the substrate In addition, the problem that the chemical solution remaining on the cover member falls on the film in the pattern formation region and generates a concave or pinhole-like defect is solved.
In the above fluid, water, ultrapure water, or the like can be used as the liquid.
Further, as the above gas, nitrogen, air that has passed through a filter (such as a chemical filter), or the like can be used.

Further, in order to achieve the above object, the unnecessary film removing apparatus of the present invention is configured to supply the chemical solution and the fluid while covering the substrate with a cover member. If the unnecessary film removing device is configured as described above, it is possible to prevent the chemical solution from being supplied to portions other than the unnecessary portion in the process of dissolving and removing the unnecessary portion of the film.
Further, in order to achieve the above object, an unnecessary film removing apparatus according to the present invention includes a substrate holding unit for holding the substrate, and a rotation driving unit for driving the substrate holding unit to rotate. The supply of fluid and the supply of fluid to the chemical supply path for discharging the chemical remaining in the chemical supply path are performed by rotating the substrate holding means. If the unnecessary film removing device is configured as described above, it is possible to strictly control the removal region where the unnecessary portion of the film is dissolved and removed.
Further, in order to achieve the above object, the unnecessary film removing apparatus of the present invention is configured to include an elevating means for attaching and / or detaching a cover member to / from the substrate. If the unnecessary film removing device has such a configuration, it is possible to prevent damage to a film formed in a region other than the unnecessary portion. The above elevating means may move the cover member up and down with respect to the substrate, or may elevate the substrate or the substrate holding means with respect to the cover member.

In order to achieve the above object, a method of manufacturing a mask blank according to the present invention comprises a thin film serving as a transfer pattern on a substrate and an unnecessary portion of a substrate with a resist film having a resist film formed thereon. A method for manufacturing a mask blank that removes using an unnecessary film removing apparatus according to (1), wherein the substrate is covered with the cover member, and a chemical solution is supplied from the chemical solution supply unit to a chemical solution supply path formed in the cover member. By dissolving an unnecessary portion of the resist film formed on the substrate and stopping the supply of the chemical by the chemical supply control unit, by supplying a fluid to the chemical supply path by the fluid supply unit, There is a method of discharging the chemical remaining in the chemical supply path.
If the method of manufacturing the mask blanks is set to such a method, after the supply of the chemical solution is stopped, by removing the chemical solution remaining in the chemical solution supply path, not only can the removal of the dissolved resist film be promoted, but also the substrate can be removed. The residue of the resist film in the unnecessary film removing portion can be reliably removed.

Further, after the supply of the chemical solution is stopped, a fluid that is insoluble in the resist film and that can discharge the chemical solution remaining in the chemical solution supply channel is supplied to the chemical solution supply channel by the fluid supply unit, and is supplied to the chemical solution supply channel. When the cover member is removed from above the substrate by removing the remaining chemical solution, the chemical solution remaining in the chemical solution supply passage of the cover member falls on the film in the pattern formation region, causing a concave or pinhole-like defect. This problem can be solved. The fluid used for the fluid supply means only needs to be insoluble in the resist film formed on the substrate, and may be a liquid or a gas.
In the case where the fluid is a liquid, it can also be used to clean a region from which unnecessary portions have been removed. As the liquid, water or ultrapure water is preferable.

In addition, nitrogen can be used as the above gas. In this case, not only gas can be supplied without passing through a filter, but also chemical contamination of the resist can be avoided. Further, as the gas, in addition to nitrogen, air that has passed through a filter (such as a chemical filter) can be used.
In order to achieve the above object, a mask blank manufacturing method according to the present invention is a method of supplying the chemical solution and the fluid while rotating the substrate and the cover member. With such a method of manufacturing the mask blanks, it is possible to strictly control the removal region where the unnecessary portion of the resist film is dissolved and removed. Therefore, it is possible to prevent a pattern defect of an auxiliary pattern such as an alignment mark, a QA (quality assurance) pattern, and a bar code pattern formed on the peripheral portion of the substrate.

  Further, in order to achieve the above object, a method of manufacturing a mask blank according to the present invention comprises supplying a chemical solution from a chemical solution supply means to a chemical solution supply path while rotating the substrate and the cover member, thereby forming a film formed on the substrate. The unnecessary portion is dissolved, the supply of the chemical solution by the chemical solution supply unit is stopped without stopping the rotation of the substrate and the cover member, and the dissolved unnecessary film is removed to the outside of the substrate by centrifugal force. When drying the unnecessary film removal portion of the substrate, the supply of the chemical solution by the chemical solution supply unit is stopped, and then the fluid supply unit supplies a fluid to the chemical solution supply channel. This is a method of discharging the chemical solution remaining in the device. By adopting such a method for manufacturing the mask blank, the removal area for dissolving and removing the unnecessary portion of the resist film can be strictly controlled, and drying of the removal area after dissolving and removing is promoted, thereby improving the throughput. can do.

In the method for manufacturing a mask blank according to the present invention, the resist film is a chemically amplified resist.
When the solvent contained in the resist is volatilized by heating to form a resist film, the chemically amplified resist is brittle compared to other resists. However, by applying the present invention, the generation of resist residue can be reliably prevented.

  According to the present invention, when removing an unnecessary portion of the film formed on the substrate, residues of the unnecessary film are generated in the unnecessary film removed portion of the substrate, and a concave or pinhole-like defect is generated in the film in the pattern formation region. The problem of occurrence can be solved, and the yield in removing unnecessary films can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Unnecessary film removal device]
First, a first embodiment of the unnecessary film removing apparatus according to the present invention will be described.
<First embodiment>
FIG. 1 is a sectional view showing a first embodiment of an unnecessary film removing apparatus according to the present invention.
As shown in FIG. 1, the unnecessary film removing apparatus 10 includes a substrate holding unit 11 for holding the substrate 1, a rotation driving unit 12 for driving the substrate holding unit 11 to rotate, a substrate 1 that covers the substrate 1 from above, and is integrated with the substrate 1. A chemically rotatable cover member 13, a chemical solution supply means 14 for supplying a chemical solution for dissolving an unnecessary film to a peripheral portion of the substrate 1 via a chemical solution supply passage 13 a formed by the cover member 13, and a chemical solution supply passage 13 a A gas supply means 15 for supplying gas to the substrate, a cup 16 surrounding the outside of the substrate holding means 11, and a drainage means 17 for discharging a chemical solution or a dissolved unnecessary film from the bottom of the cup 16. I have.
In addition, an elevating means 18 (not shown) for gripping the cover member 13 and moving up and down so that the cover member 13 can be attached to and detached from the substrate 1 can be provided. The provision of the elevating means 18 is preferable because the cover member 13 does not erroneously come into contact with the film formed on the substrate 1 and damages the film after the unnecessary film is removed.

  The chemical solution supply passage 13a includes a central portion 13b of the upper surface of the cover member 13, an annular groove 13c formed therearound, and a number of chemical solution supply holes 13d communicating from the bottom surface of the groove portion 13c to the inside of the cover member 13. That is, the chemical supplied from the chemical supply means 14 to the central portion 13 b of the upper surface of the cover member 13 flows into the groove 13 c with the rotation of the cover member 13, passes therethrough through the chemical supply hole 13 d, and passes through the peripheral portion of the substrate 1. Supplied to

  An appropriate shape, size, and formation interval of the chemical solution supply hole 13d are selected according to the viscosity of the chemical solution and the like. The shape of the chemical solution supply hole 13d can be arbitrarily set, such as a square, a rectangle, a circle, and an ellipse. The size and formation interval of the chemical solution supply holes 13d are set so that the chemical solution is uniformly supplied to the entire unnecessary film portion at a constant speed, and the necessary strength of the cover member 13 is maintained. For example, the hole diameter and the formation interval of the chemical solution supply holes 13d are set to 10 mm or less.

  In the chemical solution supply holes 13d, yarn 13e (for example, resin-based) that is resistant to the chemical solution is passed through appropriate several places (for example, four places). The thread 13e is interposed between the peripheral edge (unnecessary film facing portion) of the ceiling surface of the cover member 13 and the surface (peripheral edge) of the substrate 1 to set a gap d1 therebetween. That is, after passing through the chemical solution supply hole 13d, the thread 13e passes between the periphery of the ceiling surface of the cover member 13 and the surface of the substrate 1 and between the inner surface of the cover member 13 and the side surface of the substrate 1. And is formed in a loop shape so as to pass through the outer peripheral portion of the cover member 13.

The thickness of the thread 13e is a thickness that determines a gap d1 between the peripheral edge of the ceiling surface of the cover member 13 and the surface of the substrate 1. When a chemical solution is supplied to the gap d1, a range in which the chemical solution spreads is defined by a meniscus action. D1 is set so that For example, the gap d1 is set to 0.05 to 3 mm.
Note that the gap between the inner side surface of the cover member 13 and the side surface of the substrate 1 may be any size as long as the dissolved unnecessary film can pass through. For example, it is set in the same range as the gap d1.

  In addition, a portion of the ceiling surface of the cover member 13 except for the peripheral portion is opposed to a pattern formation region of the substrate 1, and in this region, a portion between the ceiling surface of the cover member 13 and the surface of the substrate 1 is provided. The gap d2 is set to be larger than the gap d1 between the peripheral edge of the ceiling surface and the surface of the substrate 1. In other words, the gap d2 prevents the temperature distribution of the cover member 13 from being transferred to the resist film of the substrate 1, and the convection of gas occurs in the gap to generate a temperature distribution in the resist film of the substrate 1. It is preferable to use a value that can avoid this. For example, the gap d2 is set in a range of 0.05 to 20 mm.

The substrate holding means 11 may hold the substrate 1 and rotate the substrate 1 according to the driving of the rotation driving means (motor) 12. For example, it has four support arms 11a attached to the rotation shaft 12a of the rotation drive means 12 and extending radially in the horizontal direction, and holding pedestals 11b provided at the distal end of each support arm 11a. The base 11b is configured to engage and hold the four corners of the substrate 1.
It is preferable that the substrate holding means 11 includes means for positioning the position of the cover member 13 with respect to the substrate 1.

The gas supply means 15 is, for example, a nozzle provided at a position above the cover member 13, and is set so as to supply gas from the upper surface central portion 13 b of the cover member 13 toward the chemical solution supply hole 13 d. The shape (cross section) of the nozzle constituting the gas supply means 15 can be arbitrarily set, such as a circle, an ellipse, a square, and a rectangle.
For example, the nozzle may have a rectangular shape and may be arranged along the groove 13c of the cover member 13. Although the number of nozzles is set as appropriate, in the unnecessary film removing step described later, since the substrate 1 and the cover member 13 are integrally rotated, even one nozzle can supply gas to the entire chemical solution supply path 13a. It is possible.

The pressure and flow rate of the gas supplied from the gas supply means 15 are appropriately adjusted depending on the type of resist and the type of chemical solution. For example, when supplying nitrogen gas as a gas, the pressure is 10 kPa to 500 kPa, and the flow rate is 0.1 to 30 ml / min.
Further, it is preferable that the temperature of the gas supplied from the gas supply means 15 is controlled in order to prevent uneven sensitivity of the resist. Specifically, it is preferable that the temperature be the same as or about the same as the ambient temperature at which the unnecessary film is removed.

FIG. 2 is a cross-sectional view illustrating another example of the chemical liquid supply unit and the gas supply unit.
This figure shows an example in which a nozzle having a double structure consisting of an inner nozzle and an outer nozzle covering the outer peripheral side thereof is used, the chemical liquid supply means 14 is formed by the inner nozzle, and the gas supply means 15 is formed by the outer nozzle. ing. The chemical liquid supply unit 14 and the gas supply unit 15 configured as described above may be applied to the unnecessary film removing device 10 of the first embodiment.

<Second embodiment>
FIG. 3 is a sectional view showing a second embodiment of the unnecessary film removing apparatus according to the present invention.
As shown in this figure, the unnecessary film removing apparatus 20 of the second embodiment covers a substrate 1 from above, a substrate holding unit 21 for holding the substrate 1, a rotation driving unit 22 for driving the substrate holding unit 21 to rotate. A cover member 23 rotatable integrally with the substrate 1, a chemical supply unit 24 for supplying a chemical to the peripheral portion of the substrate 1 via a chemical supply passage 23a formed by the cover member 23, and a chemical supply passage 23a. And a cup 26 surrounding the outside of the substrate holding means 21, and a draining means 27 for discharging a chemical solution or the like from the bottom of the cup 26.
In addition, similarly to the above-described first embodiment, an elevating means 28 (not shown) configured to grip the cover member 23 and move up and down may be provided so that the cover member 23 can be attached to and detached from the substrate 1. it can. The provision of the elevating means 28 is preferable because the cover member 23 does not accidentally come into contact with the film formed on the substrate 1 to damage the film after the unnecessary film is removed.

  The unnecessary film removing device 20 according to the second embodiment is different from the first embodiment in that the chemical solution supply unit 24 and the gas supply unit 25 are configured using the double-structured nozzle shown in FIG. The third embodiment is different from the first embodiment in that a member 23b and an outer cover member 23c are provided, and the inner and outer cover members 23b and 23c cooperate to form a chemical solution supply path 23a. Hereinafter, differences from the first embodiment will be described.

  The inner cover member 23b has a shape set so that the planar shape substantially matches the substrate 1 and the inner ceiling surface faces the pattern forming region of the substrate 1 in order to cover the pattern forming region of the substrate 1 from above. Have been. It is preferable that the distance between the ceiling surface of the inner cover member 23b and the surface (pattern forming region) of the substrate 1 be set in the same range as d2 in the first embodiment.

The lower end surface of the side portion of the inner cover member 23b is opposed to the peripheral edge portion of the substrate 1, and an interval adjusting member 23d is provided here. The gap adjusting member 23d defines the gap between the lower end surface of the side of the inner cover member 23b and the surface (unnecessary film removal area) of the substrate 1, and this gap is set in the same range as d1 in the first embodiment. Preferably.
That is, when the chemical is supplied from the upper portion of the inner cover member 23b, the chemical which has reached the lower end surface of the side portion along the outer surface spreads only to the peripheral portion of the substrate 1 by the meniscus action, and only the resist film in this region is dissolved. Will be.

The shape of the outer cover member 23c is set so as to cover the inner cover member 23b.
The outer cover member 23c and the inner cover member 23b are connected via a connecting member 23e, and a gap formed between the outer cover member 23c and the inner cover member 23b becomes a chemical solution supply path 23a. The outer cover member 23c has a supply port 23f at the upper center, from which the supply of the chemical by the chemical supply means 24 and the supply of the gas by the gas supply means 25 are performed.

<Third and fourth embodiments>
The unnecessary film removing apparatus 20 of the third and fourth embodiments is different from the first and second embodiments in that the gas supply means 15 and 25 are replaced by liquid supply means 19 and 29 for supplying unnecessary liquid to the film. It is different from the one. Hereinafter, differences from the first and second embodiments will be described.
The liquid supply unit 19 in the third embodiment is, for example, a nozzle provided at a position above the cover member 13. The orientation is set to supply
As the liquid supply means 29 in the fourth embodiment, the nozzle having the double structure shown in FIG. 2 is used, and the chemical liquid supply means 14 is constituted by the inner nozzle, and the liquid supply means 29 is constituted by the outer nozzle.
Examples of the liquid supplied from the liquid supply unit 19 include water and ultrapure water. When supplying ultrapure water as a liquid, the flow rate is set to 0.5 ml / min to 50 ml / min. Further, it is preferable that the temperature of the liquid supplied from the liquid supply unit 19 is controlled in order to prevent unevenness in the sensitivity of the resist. Specifically, it is preferable that the temperature be the same as or about the same as the ambient temperature at which the unnecessary film is removed.

[Unnecessary film removal method]
Next, an unnecessary film removing method using the unnecessary film removing apparatus of the present invention will be described with reference to FIG.
FIG. 4 is a timing chart showing this unnecessary film removing method.
As shown in this figure, in this unnecessary film removing method, the substrate 1 is set on the substrate holding means 11, 21 of the unnecessary film removing devices 10, 20, and the surface of the substrate 1 is covered with cover members 13, 23. After that, while rotating the substrate 1 and the cover members 13 and 23 integrally at a predetermined rotation number f1, a chemical solution is supplied from above the cover members 13 and 23, and the peripheral portion of the substrate 1 is supplied through the chemical solution supply passages 13a and 23a. The dissolving step P1 for dissolving the unnecessary film by the chemical supplied to the substrate 1 and the supply of the chemical by the chemical supply means 14 and 24 are stopped, and the substrate 1 and the cover members 13 and 23 are rotated at a predetermined rotational speed f2 (f2> f1). ), The removal and drying step P2 of removing the dissolved unnecessary film to the outside of the substrate 1 by centrifugal force and drying the removed region is included.

Then, gas supply from the gas supply means 15, 25 to the chemical liquid supply paths 13a, 23a is performed in the removal / drying step P2. As shown in FIG. 4, this gas supply may be performed at a stage where the dissolved unnecessary film is removed by centrifugal force and the removed area is dried, or after the dissolving step P1, the dissolved unnecessary film is removed. May be carried out from the stage of removing by centrifugal force.
That is, the gas supply from the gas supply means 15 and 25 to the chemical supply paths 13a and 23a is performed after the supply of the chemical liquid by the chemical supply means 14 and 24 is stopped. Preferably, the substrate 1 and the cover members 13 and 23 are supplied. Perform while rotating.

The substrate rotation speed f1 in the melting step P1 is preferably in the range of 200 to 750 rpm, and the substrate rotation speed f2 in the removal / drying step P2 is preferably in the range of 350 to 2500 rpm.
The reason why the rotation speed f2 is set to be higher than the rotation speed f1 is that when the rotation speed f2 is small, the force for unifying the resist swollen in the dissolving step P1 becomes stronger than the centrifugal force due to the rotation speed f2. This is because the unnecessary film thus removed is not removed outside the substrate 1.

FIG. 5 is a timing chart showing another example of the unnecessary film removing method.
As shown in this figure, the dissolving step P1 and the removing / drying step P2 may be repeated a plurality of times. In this case, the gas may be supplied each time the removal / drying steps P2 and P4 are performed, or may be performed only in the last removal / drying step P4. It is preferable to supply a gas every time the removal / drying steps P2 and P4 are performed in terms of the unnecessary film removal efficiency. This is because the unnecessary film removal area can be dried quickly by gas supply, and a new chemical solution can be supplied thereto.

FIG. 6 is a timing chart showing another example of the unnecessary film removing method.
The difference from the unnecessary film removing method of FIG. 4 is that, after the supply of the chemical solution is stopped, the chemical solution remaining in the chemical solution supply path is discharged, so that unnecessary liquid is supplied to the film instead of gas supply. Is a point. Supplying a liquid instead of gas supply is preferable because it can also perform cleaning of a region from which an unnecessary portion has been removed.
FIG. 7 is a timing chart showing another example of the unnecessary film removing method.
The difference from the unnecessary film removing method shown in FIG. 4 is that, after the supply of the chemical solution is stopped, in order to efficiently discharge the chemical solution remaining in the chemical solution supply path, the number of rotations f2 of the substrate during the gas supply is reduced. The rotation speed is reduced (rotation speed f3), and the chemical remaining in the chemical liquid supply path is lowered downward by the action of gravity. During the gas supply, the substrate may be rotated a plurality of times at the rotation speed f2 and the rotation speed f3.

[Manufacturing method of mask blanks]
Next, a method for manufacturing a mask blank according to the present invention will be described.
In general, a method of manufacturing a mask blank includes a thin film forming step of forming a thin film serving as a transfer pattern on a precisely polished substrate, a spin coating step of forming a resist coating film on the thin film, and an unnecessary portion of the resist film. An unnecessary film removing step of removing the resist film and a heating / cooling step of heating / cooling and drying the resist film are provided. The method of manufacturing a mask blank of the present invention is characterized in that the unnecessary film removing method described above is used in the unnecessary film removing step.

Hereinafter, each of the above steps will be briefly described.
<Thin film forming process>
The thin film serving as a transfer pattern is formed by a sputtering method, a vacuum evaporation method, a CVD method, or the like. As the material of the thin film to be the transfer pattern, a material appropriately selected according to the type of the mask blanks is used.
Mask blanks can be divided into transmission mask blanks and reflection mask blanks.

  Transmissive mask blanks use a translucent substrate such as a glass substrate as the substrate, and the thin film that becomes the transfer pattern is a thin film that causes an optical change to the exposure light used when transferring to the transfer target. The used photomask blanks. Here, the thin film that causes an optical change to the exposure light refers to a light-shielding film that blocks the exposure light, a phase shift film that changes the phase difference of the exposure light, and the like.

Therefore, the mask blanks referred to in the present invention include a normal photomask blank in which a light-shielding film is formed as a thin film having a light-shielding function, and a phase shift mask blank (half-tone type) in which a halftone film is formed as a thin film having a light-shielding function. Phase shift mask blanks), phase shift mask blanks on which a phase shift film is formed, and the like.
The reflective mask blank is a mask blank using a low-expansion substrate as a substrate and having a light reflective multilayer film and a light absorber film serving as a transfer pattern on the substrate.

<Rotation coating process>
The spin coating step is a step of uniformly applying a resist solution on a substrate with a thin film using a spin coating apparatus, and includes at least the following two steps. In other words, a resist solution is dropped on the substrate, the substrate is rotated at a predetermined rotation speed (main rotation speed) for a predetermined time (main rotation time), and a uniformizing process of making the thickness of the resist liquid uniform is performed. After the step, a drying step of rotating the substrate at a predetermined rotation number (dry rotation number) for a predetermined time (dry rotation time) to dry the uniformized resist film is included.
Conditions for the main rotation speed, the main rotation time, the drying rotation speed, and the drying rotation time are appropriately set according to the type of the resist so that the resist solution can be uniformly applied.

  The spin coating device has a chuck for placing and fixing the substrate, a nozzle for dropping the resist, a motor for rotating the chuck, and preventing the dropped resist from scattering around by rotation. And an exhaust mechanism for generating an airflow from above the cup toward the substrate.

  When applying a resist liquid on a substrate by using the above-mentioned spin coating apparatus, first, the substrate is placed and fixed on a chuck. After the resist solution is dropped from the nozzle, the substrate is rotated at a main rotation speed for a predetermined time, and the dropped resist solution is spread evenly on the substrate. After the elapse of the main rotation time, the substrate is rotated at a drying rotation number for a predetermined time to dry the resist solution. In this step, the resist film applied on the substrate is not completely dried, and the resist film formed on the peripheral portion of the substrate is dried so as not to have fluidity.

<Unnecessary film removal process>
In this unnecessary film removing step, since the above-described unnecessary film removing method is used, only special points when applied to mask blanks will be described.
The chemical is appropriately selected according to the type of the resist formed on the mask blank. For example, a solvent capable of dissolving the resist, such as a ketone, an ester, an aromatic hydrocarbon, a halogenated hydrocarbon, or an ether is used. In addition, when an unnecessary resist film formed on the peripheral portion of the substrate is selectively exposed by an exposure light source, a developing solution is supplied only to the exposed exposure region, and when the resist film is removed, a chemical solution is used. A developer is used.

The substrate rotation speed and the opening time of the dissolving step P1 and the removing / drying step P2 in the unnecessary film removing step are appropriately adjusted according to the type of the resist and the type of the chemical solution. For example, the number of rotations in the dissolving step P1 and the removing / drying step P2 is set such that the resist is harder to dissolve (when the viscosity of the resist solution is low) than when the resist is easily dissolved in the chemical solution (when the viscosity of the resist solution is low) ) Is set to be slower.
As the gas supplied to the chemical supply path, it is preferable to use a gas that does not chemically contaminate the resist. For example, nitrogen gas is used.

<Heating / cooling process>
After completing the unnecessary film removing step, the wafer is transported to the following heat treatment apparatus, subjected to heating / cooling treatment, and the resist coating film is completely dried to obtain a mask blank from which the resist film on the peripheral portion of the substrate has been removed.
The heat treatment apparatus includes a plurality of heating plates and cooling plates which are arranged adjacent to each other, and a transfer unit for transferring a substrate. The heating / cooling process is performed by holding the substrate by a pair of openable and closable transporting means, sequentially transporting the substrate to a plurality of heating plates, performing a heating process, and then transporting the substrate to a cooling plate for cooling.
The heating temperature and the heating time of the heating plate and the cooling temperature and the cooling time of the cooling plate are appropriately adjusted according to the type of the resist.

[Examples and Comparative Examples]
Next, examples and comparative examples of the present invention will be described.
<Example 1>
A light-shielding film made of chromium is formed on the surface of a transparent substrate (152.4 mm × 152.4 mm × 6.35 mm) made of synthetic quartz glass whose surface is precisely polished. A mask blank was prepared by forming a film of 4000 Å resist (manufactured by Chisso: PBSC) by a spin coating method.

  The resist film formed on the mask blanks only needs to be formed only in the pattern formation region on the substrate surface. However, the resist film after the spin coating process is not required at the peripheral portion of the substrate (substrate side surface or substrate back surface portion). Is included). Therefore, the unnecessary resist film formed around the substrate was removed by the following method.

  First, mask blanks are set on the substrate holding means 11 of the unnecessary film removing apparatus 10 shown in the first embodiment, and the cover member 13 is covered from above the mask blanks by the elevating means 18 and supplied from the chemical solution supplying means 14. While adjusting the amount, a drug solution of MCA (methyl cellosolve acetate) is supplied. At the same time, the substrate holding means 11 was rotated, and the mask blanks and the cover member 13 were rotated at a rotation speed of 200 to 500 rpm for 5 to 300 seconds. Thus, a chemical solution is supplied to the peripheral portion of the mask blank through the chemical solution supply path 13a to dissolve unnecessary portions of the resist film (dissolving step P1).

  Next, the supply of the chemical solution by the chemical solution supply unit 14 is stopped, and the substrate holding unit 11 is rotated at a rotation speed of 650 to 2,000 rpm for 3 to 200 seconds to remove the dissolved resist film to the outside of the mask blanks. The substrate holding means 11 was rotated at the same rotation speed for 2 to 100 seconds to dry the unnecessary film removal area of the mask blank (removal / drying step P2). When the unnecessary film removal region was being dried (from the start of drying to the stop of the rotation of the substrate holding unit 11), the nitrogen gas was supplied from the gas supply unit 15 to the chemical supply path 13a. The pressure of the nitrogen gas was 2.5 kPa, and the flow rate was 15 ml / min.

After the removal / drying step P2, the cover member 13 is removed from the mask blanks by the elevating / lowering means 18, and the mask blanks set on the substrate holding means 11 are transported to a heating / cooling device and subjected to a heating / cooling process. A mask blank from which the resist film was removed was obtained.
The width of removal of the resist film at the peripheral portion of the mask blank was 1.5 mm ± 0.3 mm from the side surface of the substrate so that the removal region of the resist film did not cover the pattern formation region.

By the above-mentioned method, 100 mask blanks with a resist film from which the resist film at the peripheral portion of the substrate was removed were produced.
With respect to 100 of the obtained mask blanks, when a resist residue in an unnecessary film removal region was observed with a microscope, no resist residue was found. Further, when a defect inspection of the surface of the mask blanks was performed by the surface defect inspection apparatus, no concave or pinhole-shaped defects were found in the pattern formation region.

<Example 2>
A light-shielding film made of chromium is formed on the surface of a transparent substrate (152.4 mm × 152.4 mm × 6.35 mm) made of synthetic quartz glass whose surface is precisely polished. A mask blank was prepared by forming a film of a 4000 Å chemically amplified resist (FEP171, manufactured by Fuji Film Arch Co.) by a spin coating method.
Of the chemically amplified resist film formed on the mask blanks, an unnecessary resist film formed on the periphery of the substrate was removed by the following method.
First, mask blanks are set on the substrate holding means 11 of the unnecessary film removing apparatus 10 shown in the first embodiment, and the cover member 13 is covered from above the mask blanks by the elevating means 18 and supplied from the chemical solution supplying means 14. While adjusting the amount, a chemical solution of PGMEA (propylene glycol monomethyl ether acetate) + PGME (propylene glycol monomethyl ether) is supplied. At the same time, the substrate holding means 11 was rotated, and the mask blank and the cover member 13 were rotated at a rotation speed of 500 to 800 rpm for 5 to 300 seconds. Thus, a chemical solution is supplied to the peripheral portion of the mask blank through the chemical solution supply path 13a to dissolve unnecessary portions of the resist film (dissolving step P1).
Next, the chemical solution supplied by the chemical solution supply unit 14 is stopped, and the substrate holding unit 11 is rotated at a rotation speed of 750 to 1000 rpm for 5 to 200 seconds to remove the dissolved resist film to the outside of the mask blanks. The means 11 was repeatedly rotated at the same rotation speed for 5 to 150 seconds and at a rotation speed of 100 to 350 rpm for 2 to 100 seconds to dry the unnecessary film removal area of the mask blank (removal / drying step P2). When the unnecessary film removal region was being dried (from the start of drying (stopping of the chemical solution) to the stop of rotation of the substrate holding unit 11), the gas supply unit 15 supplied nitrogen gas to the chemical solution supply path 13a. The pressure of the nitrogen gas was 2.5 kPa, and the flow rate was 15 ml / min.
After the removal / drying process P2, the cover member 13 is removed from the mask blanks by the lifting / lowering means 18, and the mask blanks set on the substrate holding means 11 are transported to a heating / cooling device and subjected to a heating / cooling process, and unnecessary heating and cooling are performed. A mask blank from which the resist film was removed was obtained.
The width of removal of the resist film at the peripheral portion of the mask blank was 1.5 mm ± 0.3 mm from the side surface of the substrate so that the removal region of the resist film did not cover the pattern formation region.
By the above-mentioned method, 100 mask blanks with a resist film from which the resist film at the peripheral portion of the substrate was removed were produced.
With respect to 100 of the obtained mask blanks, when a resist residue in an unnecessary film removal region was observed with a microscope, no resist residue was found. Further, when a defect inspection of the surface of the mask blanks was performed by the surface defect inspection apparatus, no concave or pinhole-shaped defects were found in the pattern formation region.

<Comparative Example 1>
In the unnecessary film removing apparatus 10, without supplying the nitrogen gas by the gas supply means 15, 100 mask blanks with the resist film from which the resist film at the peripheral portion of the substrate was removed were produced. Other conditions were the same as in Example 1.
With respect to 100 of the obtained photomask blanks, a resist residue in an unnecessary film removing region was observed with a microscope, and a resist residue was confirmed in 12 of the 100 photomask blanks. Further, when a defect inspection of the surface of the mask blanks was performed by a surface defect inspection device, concave or pinhole-shaped surface defects in the pattern formation region were confirmed in 23 out of 100 sheets.

<Example 3>
Using the unnecessary film removing apparatus 20 of the second embodiment described above, 100 mask blanks with a resist film from which the resist film at the peripheral portion of the substrate was removed were produced. Other conditions were the same as in Example 1.
When the resist residue in the unnecessary film removal region was observed with a microscope for 100 of the obtained photomask blanks, no resist residue was found. Further, when a defect inspection of the surface of the mask blanks was performed by the surface defect inspection apparatus, no concave or pinhole-shaped defects were found in the pattern formation region.

<Examples 4 and 5>
Using the unnecessary film removing device 20 of the third and fourth embodiments described above, 100 mask blanks with a resist film from which the resist film at the peripheral portion of the substrate was removed were produced. The liquid supplied from the liquid supply means 19, 29 was ultrapure water, and the flow rate of the ultrapure water was adjusted between 0.5 and 50 ml / min. When the resist residue in the unnecessary film removal region was observed with a microscope for 100 of the obtained photomask blanks, no resist residue was found. Further, when a defect inspection of the surface of the mask blanks was performed by the surface defect inspection apparatus, no concave or pinhole-shaped defects were found in the pattern formation region.

  In the above embodiment, PBSC was used as a resist, and MCA (methyl cellosolve acetate) was used as a chemical solution for dissolving the resist. However, the present invention is not limited to this. As the resist, a polymer resist, a chemically amplified resist, a novolak resist, and the like generally used for mask blanks can be used. The chemical used may be any one that can dissolve the resist film, such as a solvent used for diluting the resist film.

  Further, in the above embodiment, the mask blanks in which a resist film is formed on the light-shielding film has been described as an example. However, this is because an SOG (spin on glass) film is formed on a transparent substrate, Is also applicable. In that case, in addition to the light-shielding film, a film such as a transparent conductive film and an etching stopper film may be provided.

  The present invention is considered to be particularly effective when applied to a method for manufacturing mask blanks.In addition, information recording media, when removing an unnecessary portion of a protective film formed on a color filter, or in a display substrate The present invention is also applicable to a case where unnecessary portions of an insulating film formed on an electrode portion of a wiring are removed.

It is a sectional view showing a first embodiment of an unnecessary film removal device concerning the present invention. It is sectional drawing which shows the other example of a chemical | medical solution supply means and a gas supply means. It is sectional drawing which shows 2nd embodiment of the unnecessary film removal apparatus which concerns on this invention. 6 is a timing chart showing an unnecessary film removing method using the unnecessary film removing device according to the present invention. 6 is a timing chart showing another example of the unnecessary film removing method using the unnecessary film removing device according to the present invention. 6 is a timing chart showing another example of the unnecessary film removing method using the unnecessary film removing device according to the present invention. 6 is a timing chart showing another example of the unnecessary film removing method using the unnecessary film removing device according to the present invention.

Explanation of reference numerals

Reference Signs List 100 EUV reflective mask blank 100a EUV reflective mask 101 Glass substrate 102 Multilayer reflective film 103 Buffer layer 104 Absorber layer

Claims (10)

A chemical solution is supplied to an unnecessary portion of the film formed on the substrate through a cover member provided with a chemical solution supply path for supplying a chemical solution dissolvable to the film, and the film in this portion is dissolved and removed. An unnecessary film removing device,
Chemical liquid supply means for supplying a chemical liquid to the chemical liquid supply path,
Chemical supply control means for controlling the supply start and supply stop of the chemical,
A fluid supply unit that supplies a fluid to the chemical solution supply path to discharge the chemical solution remaining in the chemical solution supply path after stopping supply of the chemical solution to the chemical solution supply path,
An unnecessary film removing apparatus, comprising:   The unnecessary film removing apparatus according to claim 1, wherein the fluid is a gas or a liquid insoluble in the film.   The unnecessary film removing apparatus according to claim 1, wherein the supply of the chemical solution and the supply of the fluid are performed in a state where the cover member is covered on the substrate. The unnecessary film removing device, a substrate holding means for holding the substrate,
Rotation driving means for driving the substrate holding means to rotate, and
The supply of a chemical to the chemical supply path and the supply of a fluid to the chemical supply path for discharging the chemical remaining in the chemical supply path are performed by rotating a substrate holding unit. 3. The unnecessary film removing apparatus according to any one of 3.   The unnecessary film removing apparatus according to any one of claims 1 to 4, further comprising an elevating means for attaching and / or detaching a cover member to and from the substrate. A method of manufacturing a mask blank for removing an unnecessary portion of a substrate having a resist film on which a thin film serving as a transfer pattern on a substrate and a resist film is formed by using the unnecessary film removing apparatus according to any one of claims 1 to 5. So,
The substrate is covered with the cover member, a chemical solution is supplied from the chemical solution supply means to a chemical solution supply passage formed in the cover member, and unnecessary portions of the resist film formed on the substrate are dissolved, and the chemical solution supply is performed. A method for manufacturing a mask blank, characterized in that after the supply of the chemical solution is stopped by a control means, a fluid remaining in the chemical solution supply path is discharged by supplying a fluid to the chemical solution supply path by the fluid supply means. .   The method according to claim 6, wherein the supply of the chemical solution and the supply of the fluid are performed while rotating the substrate and the cover member. While rotating the substrate and the cover member, a chemical solution is supplied from a chemical solution supply unit to a chemical solution supply path to dissolve unnecessary portions of a film formed on the substrate, and stop the rotation of the substrate and the cover member. Without stopping the supply of the chemical solution by the chemical solution supply means, removing the dissolved unnecessary film to the outside of the substrate by centrifugal force, and drying the unnecessary film removed portion of the substrate,
7. The method according to claim 6, wherein after the supply of the chemical solution by the chemical solution supply unit is stopped, a fluid remaining in the chemical solution supply channel is discharged by supplying a fluid to the chemical solution supply channel by the fluid supply unit. Or the manufacturing method of the mask blank of 7.   The method according to any one of claims 5 to 8, wherein the fluid is a gas or a liquid insoluble in the resist film.   The method according to claim 5, wherein the resist film is a chemically amplified resist.

Images