JP7561555B2 - Foreign matter removal method and foreign matter removal device - Google Patents

Description

The present invention relates to a foreign matter removal method and a foreign matter removal device, and more particularly to a foreign matter removal method and a foreign matter removal device for removing foreign matter adhering to an EUV mask pellicle used in an EUVL (Extremely Ultraviolet Lithography) process.

Pellicles are used to prevent foreign matter from adhering to the pattern surface of a mask substrate. Pellicles for EUV masks (hereafter referred to as EUV pellicles) are very thin, with a thickness of about 50 nm, and are known to be difficult to clean and dry. For example, EUV pellicles are easily torn by even the slightest air current, so foreign matter cannot be removed by air blowing. It is also difficult to remove minute foreign matter from thin films other than EUV pellicles by air blowing.

However, even if a foreign particle measuring a few microns or less adheres to the pellicle, it is not imaged on the wafer and therefore does not affect the transfer characteristics of the mask. Furthermore, since minute foreign particles have a small mass, they are subjected to small forces due to acceleration. Therefore, the intermolecular forces acting between the minute foreign particle and the pellicle are relatively large, and it is considered unlikely that the minute foreign particle will move to the pattern surface of the mask.

Meanwhile, a foreign matter removal method is known in which foreign matter adhering to the back surface of a mask substrate is removed using an adhesive material such as urethane resin, silicone resin, or acrylic resin. FIG. 1 is a schematic diagram showing an overview of a foreign matter removal method according to the prior art. In the foreign matter removal method according to the prior art, a rod-shaped member 111 to which an adhesive material 3 such as urethane resin is attached is brought close to a foreign matter 5 on the back surface of a mask substrate 4 (step S101), the adhesive material 3 is pressed against the foreign matter 5 (step S102), and the adhesive material 3 is peeled off from the back surface of the mask substrate 4 to remove the foreign matter (step S103).

Japanese Unexamined Patent Publication No. 18130/1983 Japanese Unexamined Patent Publication No. 2-13952 Japanese Patent Application Publication No. 3-155550 Japanese Patent Application Publication No. 3-204648 Japanese Patent Application Publication No. 3-231248 Japanese Patent Application Publication No. 5-297572 Japanese Patent Application Publication No. 6-29175 Japanese Patent Application Publication No. 6-260464 Japanese Patent Application Publication No. 9-260245 Japanese Patent Application Publication No. 11-143054 JP 2005-33072 A JP 2008-116979 A JP 2008-304737 A JP 2009-164464 A JP 2009-265176 A JP 2010-45283 A JP 2010-54773 A JP 2011-81282 A JP 2012-203163 A JP 2013-68786 A

However, the possibility of foreign particles on the order of microns moving onto the pattern surface is not necessarily zero. If a foreign particle attached to the inside of the pellicle (the mask side) moves onto the pattern surface of the mask, the foreign particle will be transferred to the wafer as a pattern defect. In addition, if the size of the attached foreign particle is several tens of microns or more, the pellicle may become hot due to absorption of EUV light and be damaged.

However, as mentioned above, EUV pellicles are not easy to clean, which results in very low manufacturing yields. If the foreign matter removal method shown in Figure 1 is applied to a pellicle, there is a risk that the EUV pellicle will be torn when the adhesive member is pulled away from the EUV pellicle.

The object of the present invention is to solve these problems and to provide a method and apparatus for removing foreign matter from thin films such as EUV pellicles.

The foreign matter removal method according to the present invention includes a heating step of heating an adhesive member, an attachment step of attaching the heated adhesive member to an end face of a rod-shaped member, and a removal step of bringing the adhesive member attached to the rod-shaped member into contact with a foreign matter on a thin film to remove the foreign matter.

The foreign matter removal device according to the present invention also includes a heating unit that heats the adhesive material, and a driving unit that attaches the heated adhesive material to an end face of a rod-shaped member and brings the adhesive material attached to the rod-shaped member into contact with foreign matter on a thin film to remove the foreign matter.

The present invention provides a method and device for removing foreign matter from thin films such as EUV pellicles.

1A to 1C are schematic diagrams illustrating an overview of a method for removing foreign matter on the rear surface of a mask substrate. 1 is a schematic diagram showing an overview of a foreign matter removal device according to an embodiment. FIG. 2 is a schematic diagram showing a method for producing sheet-shaped asphalt used by the foreign matter removal device according to the embodiment. FIG. 2 is a schematic diagram showing a method for producing sheet-shaped asphalt used by the foreign matter removal device according to the embodiment. 5A to 5C are schematic diagrams illustrating an overview of a method for attaching an adhesive member to an end surface of a rod-shaped member in a foreign matter removal method according to an embodiment. 5A to 5C are schematic diagrams illustrating an overview of a method for attaching an adhesive member to an end surface of a rod-shaped member in a foreign matter removal method according to an embodiment. 5A to 5C are schematic diagrams illustrating a method for removing an adhesive material from an end surface of a rod-shaped member by a foreign matter removal device according to an embodiment. FIG. 2 is a diagram showing an example of the configuration of an optical system of a foreign matter removal device according to an embodiment. 5A and 5B are schematic diagrams illustrating a method in which the foreign matter removal device according to the embodiment detects contact between a thin film and an adhesive member. 5A and 5B are schematic diagrams illustrating a method in which the foreign matter removal device according to the embodiment detects contact between a thin film and an adhesive member. 2 is a block diagram showing a functional configuration of a processing device of the foreign matter removal apparatus according to the embodiment. FIG. 3 is a flowchart showing a procedure of a foreign matter removal method according to the embodiment.

The specific configuration of this embodiment will be described below with reference to the drawings. The following description shows a preferred embodiment of the present invention, and the scope of the present invention is not limited to the following embodiment. In the following description, parts with the same reference numerals indicate substantially the same contents.

(Embodiment)
2 is a schematic diagram showing an overview of the foreign matter removal device 1 according to the embodiment. The foreign matter removal device 1 includes a removal unit 11, a heating laser light source 12, a polyimide film 13 coated with an adhesive member 3, a glass plate 14, an optical system 20, and a control device 30.

For clarity of explanation, FIG. 2 shows a three-dimensional orthogonal coordinate system of XYZ. The Z direction is the vertical direction, which is parallel to the thickness direction of the thin film 2. Therefore, the Z direction is the height direction. The X and Y directions are parallel to the edges of the thin film 2.

The foreign matter removal device 1 is a device that removes foreign matter on a thin film 2 using an adhesive material 3. The thin film 2 is, for example, an EUV pellicle before being attached to a mask. However, the thin film 2 is not limited to an EUV pellicle. The thin film 2 is mounted on a stage (not shown) and can be moved in the X, Y, and Z directions. Because the stage is a hollow stage, it is possible to bring the adhesive material 3 into contact with the -Z side surface of the thin film 2 (hereinafter referred to as the back surface).

The polyimide film 13 is placed horizontally, and the adhesive material 3 is applied to the lower side (-Z side). The adhesive material 3 is an adhesive resin, and may be a natural resin such as asphalt, or a synthetic resin such as EVA (Ethylene-vinyl acetate). Asphalt is preferable because it is black and can be easily heated by irradiation with laser light. The adhesive material 3 does not need to have adhesiveness at room temperature, but only needs to have adhesiveness when heated.

The adhesive material 3 may be applied to a film other than a polyimide film or a plate-like material such as a glass plate. The polyimide film 13 to which the adhesive material 3 is applied may be placed on a stage (not shown).

Next, asphalt sheet will be described as an example of a polyimide film coated with adhesive material 3. FIG. 3 is a schematic diagram showing an overview of a method for producing asphalt sheet. A polyimide film 13 is laid on a hot plate 43. Asphalt 3a is heated through polyimide film 13. Asphalt 3a is rolled by roller 41 through fluororesin film 42.

Figure 4 shows a schematic cross-sectional view of Figure 3 when viewed from a direction perpendicular to the central axis of roller 41. The right side of Figure 4 is an enlarged view of the area surrounded by a dotted line in the left side of the figure. A spacer 44 is disposed at the end of roller 41. Spacer 44 is, for example, a SUS (Steel Use Stainless) plate. Spacer 44 makes it possible to appropriately control the thickness of asphalt 3a.

Next, the procedure for producing the sheet-like asphalt, the outline of which is shown in FIG. 3 and FIG. 4, will be described in detail. First, the polyimide film 13 is placed on the hot plate 43 and heating is started. Next, the spacer 44 is placed on the polyimide film 13. The spacer 44 may be about two SUS plates. Next, a lump of asphalt 3a is placed on the polyimide film 13 and softened. Next, the fluororesin film 42 is placed on the asphalt 3a. Next, the roller 41 is preheated using the hot plate 43. Next, the heated roller 41 is rolled on the fluororesin film 42. Next, the polyimide film 13, asphalt 3a, and fluororesin film 42 are lifted from the hot plate 43 as a whole, and placed on a flat table while still warm to cool to room temperature. Next, the polyimide film 13 and the like are adhered to a frame, and the portion protruding from the frame is cut off. The fluororesin film 42 is peeled off from the asphalt 3a before use.

Returning to FIG. 2, the glass plate 14 is used to remove the adhesive member 3 attached to the rod-shaped member 111 described below after the foreign matter has been adhesively removed from the thin film 2. Note that a plate-shaped member other than a glass plate may be used as the member used to remove the adhesive member 3.

The removal unit 11 includes a rod-shaped member 111 and a drive unit 112 that drives the rod-shaped member 111. The drive unit 112 is controlled by a control device 30 described below. As shown in FIG. 2, the rod-shaped member 111 may be a part of a wire such as an optical fiber or a glass fiber. It is preferable that the end face of the rod-shaped member 111 is cut perpendicular to the long axis of the wire. The rod-shaped member 111 can be driven in the X direction, Y direction, and Z direction by the drive unit 112. The rod-shaped member 111 may be a light-guiding member (e.g., an optical fiber) through which light passes.

The driving unit 112 brings the end face of the rod-shaped member 111 into contact with the adhesive member 3 applied to the polyimide film 13, and adheres the adhesive member 3 to the end face of the rod-shaped member 111. The driving unit 112 then brings the adhesive member 3 adhered to the rod-shaped member 111 into contact with a foreign object on the thin film 2, and removes the foreign object. After removing the foreign object, the driving unit 112 removes the adhesive member 3 adhered to the rod-shaped member 111 using the glass plate 14.

The heating laser light source 12 irradiates the adhesive material 3 applied to the polyimide film 13 with laser light, liquefying or softening the adhesive material 3. This makes it possible to attach the adhesive material 3 to the end surface of the rod-shaped member 111.

The heating laser light source 12 also heats the adhesive material 3 attached to the end surface of the rod-shaped member 111. This allows the temperature of the adhesive material 3 to be maintained at a temperature where the fluidity is negligible and where the viscosity is optimal. If the adhesive material 3 has an appropriate viscosity at room temperature, there is no need to control the viscosity of the adhesive material 3 by laser irradiation. When the adhesive material 3 with the appropriate viscosity is brought into contact with a foreign object, the foreign object penetrates into the adhesive material 3, such as asphalt, and the foreign object can be removed by pulling away the rod-shaped member 111.

In addition, the heating laser light source 12 heats the adhesive material 3 attached to the end surface of the rod-shaped member 111, liquefying or softening the attached adhesive material 3, making it possible to remove it using the glass plate 14.

When the rod-shaped member 111 is a part of an optical fiber, the heating laser light source 12 may be coupled to the optical fiber. In such a case, the laser light emitted from the end face of the rod-shaped member 111 heats the adhesive material 3 applied to the polyimide film 13. In addition, the laser light that passes through the optical fiber heats the adhesive material 3 attached to the end face of the rod-shaped member 111 (optical fiber). This heats an area approximately the same as the diameter of the optical fiber (e.g. 125 μm). Note that the rod-shaped member 111 does not have to be an optical fiber as long as it is a light-guiding member through which light passes.

Figures 5 and 6 are schematic diagrams showing an overview of a method for attaching an adhesive member 3 to an end surface of a rod-shaped member 111. Figure 5 shows a case where laser light L1 is emitted from the end surface of the rod-shaped member 111 (optical fiber), and Figure 6 shows a case where laser light L2 is emitted from a location other than the end surface of the rod-shaped member 111.

In FIG. 5, first, laser light is input into the optical fiber, and laser light L1 is emitted from the end face of the optical fiber (end face of the rod-shaped member 111) to heat and melt the asphalt 3a (step S201). The heated asphalt 3a liquefies or softens. Next, the drive unit 112 brings the end face of the rod-shaped member 111 into contact with the adhesive member 3 and separates them. As a result, the asphalt 3a with a spherical tip adheres to the end face of the rod-shaped member 111 (step S202). By cooling at room temperature, the fluidity of the asphalt 3a is almost completely lost.

In FIG. 6, laser light L2 is irradiated through the polyimide film 13 to heat and melt the asphalt 3a (step S301). In such a case, the rod-shaped member 111 does not have to be an optical fiber. As in FIG. 5, the drive unit 112 brings the end face of the rod-shaped member 111 into contact with the asphalt 3a and separates them. This causes the asphalt 3a to adhere to the rod-shaped member 111 (step S302). Note that the polyimide film 13 may be mounted on a stage (not shown), and the asphalt 3a may be heated by the laser light focused by the objective lens 24 in FIG. 2.

The adhesive member 3 may be heated by means other than laser light, for example, by a heater or the like. However, laser heating is preferred in that it is possible to heat the adhesive member 3 in an amount necessary to adhere it to the rod-shaped member 111. In particular, by using an optical fiber as the rod-shaped member, it is possible to irradiate the laser light at an appropriate position.

Due to the effects of surface tension and gravity, the adhesive material forms a convex shape on the end face of the rod-shaped member 111. By using a convex adhesive material, the contact area between the thin film 2 and the adhesive material can be reduced, and therefore the tensile force applied to the thin film 2 can be reduced.

Figure 7 is a schematic diagram showing an overview of a method for removing asphalt 3a containing foreign matter from the end face of the rod-shaped member 111 after removing the foreign matter. First, the asphalt 3a attached to the rod-shaped member 111 is heated and melted by irradiation with laser light (step S401). Here, if the rod-shaped member 111 is an optical fiber, the asphalt 3a may be irradiated and heated by laser light passing through the inside of the optical fiber. In addition, the glass plate 14 may be mounted on a stage not shown, and the laser light passing through the objective lens 24 in Figure 2 may be irradiated onto the asphalt 3a through the glass plate 14. Next, the end face of the rod-shaped member 111 is brought into contact with the glass plate 14 and then pulled away, so that a part of the asphalt 3a moves to the glass plate 14 (step S402). Next, the processes of steps S401 to S402 are repeated while changing the contact position until the adhesion of the asphalt 3a to the glass plate 14 decreases (step S403). This makes it possible to remove asphalt 3a adhering to the rod-shaped member 111 to an extent that does not cause problems. It is also possible to confirm that asphalt 3a has been sufficiently removed using a confocal optical system, which will be described later.

Returning to FIG. 2, the optical system 20 includes a confocal optical system and an optical system for foreign body inspection. The optical system 20 may further include a contact detection optical system that detects contact between the thin film 2 and the adhesive member 3. The confocal optical system includes an objective lens 24, measures the height (position in the Z direction) of the thin film 2, and measures the shape and height of the adhesive member 3 attached to the end surface of the rod-shaped member 111. The confocal optical system is also called a confocal microscope optical system.

The foreign body inspection optical system includes a laser light source 26a that irradiates the thin film 2 with laser light from the +Z side, and a laser light source 26b that irradiates the thin film 2 with laser light from the -Z side. The laser light scattered by the foreign body is collected by the objective lens 24, and the position (X, Y) of the foreign body is detected. In addition, by comparing the scattered light intensity of the laser light emitted from the laser light source 26a with the scattered light intensity of the laser light emitted from the laser light source 26b, it is possible to determine whether the foreign body is present on the +Z side surface (hereinafter referred to as the front surface) or the -Z side surface (hereinafter referred to as the back surface) of the thin film 2.

Figure 8 is a configuration diagram illustrating the optical system 20. As shown in Figure 8, the optical system 20 includes an illumination light source 21, a beam splitter 22, a dichroic mirror 23, an objective lens 24, a photodetector 25, laser light sources 26a and 26b, and a scattered light detector 27. The thin film 2 to be measured is placed on a hollow stage 10 and can be moved in the X, Y, and Z directions.

The optical system 20 shown in FIG. 8 has been appropriately simplified. The optical system 20 may be provided with optical elements, lenses, optical scanners, mirrors, filters, beam splitters, etc. other than those described above.

First, the confocal optical system will be described. The illumination light source 21 generates illumination light L11. The illumination light source 21 generates line-shaped illumination light. The illumination light source 21 is a lamp light source, an LED (Light Emitting Diode) light source, a laser light source, or the like. Note that the confocal optical system may not be a line confocal optical system, but may be a normal confocal optical system. In such a case, it is preferable to use a point light source.

The beam splitter 22 is, for example, a half mirror, and reflects approximately half of the illumination light L11 in the direction of the thin film 2. The illumination light L11 reflected by the beam splitter 22 is incident on the dichroic mirror 23.

The dichroic mirror 23 has the property of reflecting the scattered light S12, 13 described below, and transmitting the illumination light L11 and the reflected light R11 described below. Therefore, the illumination light L11 reflected by the beam splitter 22 transmits through the dichroic mirror 23 and enters the objective lens 24. The illumination light L11 that enters the objective lens 24 is condensed so as to be focused on a thin film 2 such as an EUV pellicle. The optical axis of the objective lens 24 is parallel to the Z direction.

The reflected light R11 reflected by the surface of the thin film 2 is collected by the objective lens 24, passes through the dichroic mirror 23 and the beam splitter 22, and enters the photodetector 25. This allows the photodetector 25 to capture an image of the thin film 2. The photodetector 25 is, for example, a line sensor equipped with multiple pixels. Specifically, a line CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) line sensor can be used as the photodetector 25. Therefore, multiple pixels are arranged in a row on the light receiving surface of the photodetector 25.

The light receiving surface of the photodetector 25 is disposed at a position conjugate with the focal plane of the objective lens 24. The illumination light focused by the objective lens 24 forms a linear illumination area on the focal plane. On the light receiving surface of the photodetector 25, the reflected light is focused in a line shape.

In a confocal optical system, the Z position where the brightness is maximum represents the height of the thin film 2, so the height of the thin film 2 can be measured.

Next, the optical system for scattered light inspection will be described. The laser light L12 emitted from the laser light source 26a is scattered by foreign matter on the front or back surface of the thin film 2, and the scattered light S12 is collected by the objective lens 24. The laser light L12 emitted from the laser light source 26b is scattered by foreign matter on the front or back surface of the thin film 2, and the scattered light S12 is collected by the objective lens 24. The scattered light S12 and S13 are reflected by the dichroic mirror 23 and enter the scattered light detector 27. The position (X, Y) of the foreign matter on the thin film 2 can be identified from the intensity of the scattered light S12 or S13. Also, by comparing the intensity of the scattered light S12 with the intensity of the scattered light S13, it is possible to identify whether the foreign matter is present on the front or back surface of the thin film 2.

As described above, the height of the thin film 2 can be measured using a confocal optical system, and therefore contact between the thin film 2 and the adhesive member 3 attached to the rod-shaped member 111 can be detected from a change in the height of the thin film 2. However, if the optical system 20 further includes an optical system for contact detection, it becomes possible to detect the contact more quickly. The contact may be detected by measuring the change in the height of the thin film 2 using an optical lever method, or by measuring the vibration of the thin film 2.

Figure 9 shows a method for measuring the height of the thin film 2 using the optical lever method. First, the optical system shown at the top will be described. A light beam emitted from a light source 201 such as a laser diode is reflected by a dichroic mirror 202, passes through the left side of the objective lens 24, and enters the thin film 2 as incident light L21. Reflected light L22 specularly reflected by the thin film 2 passes through the right side of the objective lens 24 and is reflected by the dichroic mirror 202. The light beam reflected by the dichroic mirror 202 enters a photodetector 203. For example, a two-part photodiode can be used as the photodetector 203. The two-part photodiode is positioned so that light enters the center before the adhesive member 3 comes into contact with the thin film 2.

In FIG. 9, before the thin film 2 and the adhesive member 3 come into contact, the upper surface of the thin film 2 is irradiated with laser light L21 and the reflected light L22 is received (step S501). When the adhesive member 3 and the thin film 2 come into contact, the receiving position of the reflected light L22 changes (step S502), making it possible to detect the contact. The foreign matter removal device 1 may detect the contact by, for example, the thin film 2 being pushed up by the adhesive member 3 and increasing in height. The foreign matter removal device 1 may also detect that the thin film 2 has been attracted to the adhesive member 3 by electrostatic force and has come into contact. For example, if the height of the thin film 2 decreases and is pushed up by the adhesive member 3 to return to its original height, it can be said that the thin film 2 and the adhesive member 3 have come into contact.

In FIG. 10, before the thin film 2 and the adhesive member 3 come into contact with each other, the thin film 2 is vibrated by the acoustic vibration device 204, and the vibration amplitude of the thin film 2 is measured by a Doppler vibrometer (not shown) (step S601). Then, the vibration amplitude of the thin film 2 decreases, and the contact between the thin film 2 and the adhesive member 3 is detected (step S602).

In this way, when contact between the thin film 2 and the adhesive member 3 is detected, the driving unit 112 shown in FIG. 2 may separate the rod-shaped member 111 and the thin film 2. This makes it possible to reduce the contact area between the adhesive member 3 attached to the end face of the rod-shaped member 111 and the thin film 2. Therefore, it becomes possible to reduce the tensile force applied to the thin film 2.

Returning to FIG. 2, the control device 30 is a computer that controls the operation of the drive unit 112, and includes a memory and a processor. FIG. 11 is a block diagram showing the functional configuration of the control device 30. The control device 30 includes a first control unit 31 that brings the adhesive member 3 on the polyimide film 13 into contact with the rod-shaped member 111, a second control unit 32 that brings the adhesive member 3 attached to the rod-shaped member 111 into contact with the foreign matter on the thin film 2, and a third control unit 33 that brings the adhesive member 3 attached to the rod-shaped member 111 into contact with the glass plate 14. The second control unit 32 executes a process of bringing the end face of the rod-shaped member 111 close to the foreign matter on the thin film 2, and a process of moving the end face of the rod-shaped member 111 away from the thin film 2 according to the contact detection result of the optical system 20.

Figure 12 is a flow chart illustrating the flow of the foreign matter removal method according to the embodiment. The rod-shaped member 111 is an optical fiber, and the heating laser light source 12 is connected to the optical fiber. The adhesive member 3 is asphalt 3a. First, when the heating laser light source 12 inputs laser light into the optical fiber, the laser light is emitted from the end face (output end of the optical fiber) of the rod-shaped member 111, and the sheet-like asphalt 3a on the polyimide film 13 is heated (step S701). Next, the end face of the rod-shaped member 111 (optical fiber) is brought into contact with the partially liquefied asphalt 3a, and a convex-shaped asphalt 3a is formed on the end face (step S702).

Next, the heating laser light source 12 inputs laser light into the optical fiber, thereby starting heating of the asphalt 3a attached to the output end (step S703). Next, the laser light source 26b included in the foreign body inspection optical system is used to irradiate the thin film 2 such as an EUV pellicle with laser light from its back side, and the scattered light S13 is detected to identify the position (X, Y) of the foreign body (step S704). Next, the laser light source 26a included in the foreign body inspection optical system is used to irradiate the thin film 2 with laser light from its front side, detect the scattered light S12, and compare it with the scattered light intensity S13 to identify whether the foreign body detected in step 704 is present on the front or back side of the thin film 2 (step S705). In the following, it is assumed that the foreign body is present on the back side of the thin film 2.

Next, the height of the thin film 2, such as an EUV pellicle, is measured using a confocal optical system (step S706). Next, the stage on which the thin film 2 is placed is temporarily removed from the measurement area of the optical system (step S707). Next, the shape and height of the asphalt 3a deposited in step S702 are measured using the confocal optical system (step S708). Next, the rod-shaped member 111 is removed from the measurement area of the optical system, and the stage on which the thin film 2 is attached is moved so that the foreign object on the thin film 2 is positioned at the center of the field of view of the confocal optical system (step S709).

Next, the asphalt 3a attached to the rod-shaped member 111 is brought close to the foreign object on the back surface of the thin film 2 (step S710). Next, contact between the asphalt 3a and the thin film 2 is detected, and the rod-shaped member 111 is inverted according to the detection result (step S711). In step S711, the contact may be detected by measuring the height of the thin film 2 using an optical lever type contact detection optical system or a confocal optical system. Also, in step S711, the thin film 2 may be acoustically vibrated to measure the vibration amplitude, and contact between the adhesive member 3 and the thin film 2 may be detected based on the reduction in the amplitude. Next, the rod-shaped member 111 is removed from the measurement area of the optical system, and it is confirmed whether the foreign object has been removed using an optical system for foreign object inspection (step S712).

Next, the asphalt 3a containing the foreign matter is laser-heated by the laser light passing through the optical fiber, and the heated asphalt 3a is pressed against the glass plate 14 to remove the foreign matter and the used asphalt 3a (step S713). After step S713, the foreign matter removal device 1 reattaches the asphalt 3a on the polyimide film 13 to the end face of the rod-shaped member 111.

Finally, the effect of this embodiment will be explained. The viscosity of adhesive materials such as asphalt changes depending on the temperature, and at high temperatures the viscosity is low. When the end face of a rod-shaped material such as an optical fiber is wetted in this state, a smooth convex surface is formed at the end due to surface tension and gravity.

When an adhesive material such as asphalt is heated with a laser, its viscosity decreases and it becomes sticky. When the adhesive material with this adhesive force is brought into contact with a foreign object, the foreign object adheres to the adhesive material, making it possible to peel the foreign object from a thin film such as an EUV pellicle.

Adhesive materials such as asphalt lose their adhesive strength when the temperature is low, and lose their viscosity when the temperature is high, causing the shape to become unstable. Therefore, optimization of the adhesive material is necessary. According to this embodiment, it is possible to appropriately adjust the temperature by adjusting the power of the laser light.

In addition, because only a small amount of adhesive material attached to the tip of the rod-shaped member is heated, the amount of mechanical deformation of the rod-shaped member is small, and the tip position of the adhesive material is stable.

In addition, because the tip of the rod-shaped member has a convex shape, the contact area with the thin film is small. Also, by controlling the distance between the height of the adhesive member and the height of the thin film, it is believed that the adhesive member only comes into contact with foreign matter and does not come into contact with the thin film. With this method, the tensile force applied to the EUV pellicle is small, and the EUV pellicle will not break.

Other Embodiments
In the above embodiment, the adhesive material is heated through the optical fiber when controlling the viscosity of the adhesive material, but laser light may be irradiated from outside the optical fiber. For example, the adhesive material 3 attached to the end surface of the rod-shaped member 111 may be heated by irradiating laser light from above the thin film 2 in FIG. 2 through the objective lens 24.

In such a case, the rod-shaped member 111 does not have to be an optical fiber. The rod-shaped member 111 may be, for example, a glass fiber. When the thin film 2 is a pellicle, it is desirable that the wavelength of the laser light is 1.56 μm, which is less absorbed by the pellicle. When the asphalt 3a attached to the rod-shaped member 111 is irradiated with laser light while in contact with a foreign object, the asphalt 3a is softened by heating, making it possible to incorporate the foreign object into the asphalt 3a.

In this embodiment, if contact between the asphalt 3a and a foreign object is detected in step S711 of FIG. 12, the operation of the rod-shaped member 111 is stopped. Then, an IR heating laser is irradiated from the objective lens 24 to heat the asphalt 3a adhering to the end face of the rod-shaped member 111. The above operation causes the foreign object to enter the asphalt 3a. After irradiating the laser for a certain period of time, the rod-shaped member 111 is slowly moved away from the thin film 2, thereby removing the foreign object from the thin film 2. Finally, a scattered light inspection is performed to confirm whether the foreign object has been removed from the thin film 2.

Here, when separating the rod-shaped member 111 and the thin film 2, the heating IR laser may be left irradiated. In this case, when the asphalt 3a separates from the thin film 2, the thermal conductivity drops sharply, causing the temperature of the thin film 2 to rise. As a result, even if a small amount of asphalt is attached to the thin film 2, it evaporates, and no asphalt remains on the thin film 2.

The above describes an embodiment of the present invention, but the present invention includes appropriate modifications that do not impair its objects and advantages, and is not limited to the above embodiment.

REFERENCE SIGNS LIST 1 Foreign matter removal device 2 Thin film 3 Adhesive member 4 Mask substrate 5 Foreign matter 11 Removal unit 111 Rod-shaped member 112 Driving unit 12 Heating laser light source 13 Polyimide film 14 Glass plate 20 Optical system 21 Illumination light source 22 Beam splitter 23 Dichroic mirror 24 Objective lens 25 Photodetector 26a, 26b Laser light source 27 Scattered light detector 30 Control device 31 First control unit 32 Second control unit 33 Third control unit 41 Roller 42 Fluoroplastic resin film 43 Hot plate 44 Spacer

Claims (9)

a heating step of heating the adhesive member;
an adhering step of adhering the heated adhesive member to an end surface of a rod-shaped member;
a removing step of contacting the adhesive member attached to the rod-shaped member with a foreign matter on the thin film to remove the foreign matter;
Including,
the rod-shaped member is a light-guiding member through which light passes,
The heating step comprises:
irradiating the adhesive member with laser light emitted from the end surface of the light guiding member to heat the adhesive member;
The attaching step comprises:
The heated adhesive member is attached to the end surface of the light guide member.
Foreign body removal method. The light guiding member is an optical fiber.
The method for removing foreign matter according to claim 1 . a heating step of heating the adhesive member;
an adhering step of adhering the heated adhesive member to an end surface of a rod-shaped member;
a removing step of contacting the adhesive member attached to the rod-shaped member with a foreign matter on the thin film to remove the foreign matter;
Including,
The removing step includes:
the adhesive member attached to the end surface is heated by irradiating it with a laser beam, and the heated adhesive member is brought into contact with the foreign matter on the thin film to remove the foreign matter;
Foreign body removal method. The removing step includes:
the adhesive material attached to the end surface is heated by irradiating the adhesive material with a laser beam that has passed through the optical fiber, and the heated adhesive material is brought into contact with the foreign matter on the thin film, thereby removing the foreign matter.
The method for removing foreign matter according to claim 2 . The removing step includes:
an approaching step of bringing the end surface close to the foreign object on the thin film;
a detection step of detecting contact between the adhesive member attached to the end surface and the thin film;
a separating step of separating the end surface from the thin film in response to a detection result of the detecting step;
The method for removing foreign matter according to claim 1 , further comprising: the detection step detects contact between the adhesive member attached to the end surface and the thin film based on a position change in a thickness direction of the thin film or a vibration change in the thickness direction of the thin film.
The method for removing foreign matter according to claim 5 . The adhesive material is asphalt.
The method for removing foreign matter according to any one of claims 1 to 6 . The thin film is an EUV pellicle for covering a mask pattern of an EUV mask.
The method for removing foreign matter according to any one of claims 1 to 7 . A heating unit that heats the adhesive material;
a driving unit that attaches the heated adhesive member to an end surface of a rod-shaped member and brings the adhesive member attached to the rod-shaped member into contact with a foreign matter on a thin film to remove the foreign matter; and
Equipped with
the rod-shaped member is a light-guiding member through which light passes,
The heating unit includes:
The adhesive member is heated by irradiating the adhesive member with laser light emitted from an end surface of the light guiding member;
The drive unit is
The heated adhesive member is attached to the end surface of the light guide member.
Foreign body removal device.

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