JP3240261B2 - Pellicle manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LSI,
The present invention relates to a method for producing a pellicle for lithography, which is used as a refuse for a lithographic mask when producing a semiconductor device such as a liquid crystal display panel or the like.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices such as LSIs and VLSIs or liquid crystal display panels, patterning is performed by irradiating light to a semiconductor wafer or a liquid crystal original plate. If dust adheres to the (lithography mask), the dust absorbs light or bends the light, causing the transferred pattern to be deformed or having sharp edges, and the base to be black. There is a problem that the size, quality, appearance and the like are impaired due to contamination. For this reason, these operations are usually performed in a clean room, but it is difficult to keep the original exposure plate clean even in this clean room, so that the surface of the original exposure plate often passes light for exposure to avoid dust. The method of sticking a pellicle to be made is taken. In this case, since the dust does not directly adhere to the surface of the original exposure plate but adheres to the pellicle film, if the focus is set on the pattern of the exposure original plate during lithography, the dust on the pellicle film is irrelevant to the transfer. Become.

The basic configuration of a pellicle is such that a transparent pellicle film made of nitrocellulose, cellulose acetate, or the like, which transmits light used for exposure well, is placed on a pellicle frame made of aluminum, stainless steel, polyethylene, or the like. A solvent is applied and then fixed and air-dried for adhesion (see JP-A-58-219023) or an adhesive such as an acrylic resin or an epoxy resin (US Pat. No. 4,861,402; 63-2770
No. 7, Japanese Patent Application Laid-open No. 7), and an adhesive layer made of a polybutene resin, a polyvinyl acetate resin, an acrylic resin or the like because an original exposure plate is mounted below the pellicle frame, and a release layer for the purpose of protecting the adhesive layer. (Separator).

In the production of this pellicle, a pellicle film having the same size as that of the pellicle film is not usually adhered to a frame holding the pellicle film, but a film somewhat larger than the pellicle frame is produced and attached to the pellicle frame. After that, the unnecessary film protruding outside the pellicle frame is cut and removed. As a method of cutting and removing unnecessary film, a mechanical method of cutting and removing with a cutter or the like, a thermal method of cutting with a heater or a laser, and a dissolving method of cutting and removing a solvent capable of dissolving a pellicle film by dropping have been proposed. .

[0005]

The method of dissolving and removing a film with a solvent, which is one of the above-mentioned methods of removing an unnecessary film, has substantially no dust and has a good cut surface shape. Is an excellent way. However, the problem of this method is that the solvent is dropped along the outer peripheral portion of the pellicle bonding surface on the pellicle frame, and the dropped liquid naturally proceeds along the chamfered portion of the end of the frame to dissolve the film. For this reason, there is a problem that it is difficult to control the solvent used at the time of cutting (for example, control of the amount of the solvent to be dropped, the drop position, and the path of the liquid after the drop). Therefore, in the unnecessary film cutting and removing process, the solvent used for cutting unexpectedly proceeds on the pellicle film and the frame, dissolving the pellicle film, and generating stains on the film and the pellicle frame. In addition, foreign matters are left behind, which significantly reduces the product yield.

In the method of directly cutting a film by a laser, a sharp cut surface can be obtained. On the other hand, a very high energy is converged to cut a pellicle film having a high transmittance at various laser oscillation wavelengths. Since irradiation had to be performed, it was difficult to control the energy on the irradiation surface, and evaporation of the film, that is, generation of foreign matter was likely to occur, and the yield was low. On the other hand, when cutting with a device such as a die cutter incorporating a heater, the film can be cut in a short time, but a cutter with the same shape as the pellicle frame with very high precision is required In addition, it is necessary to position the cutter with high accuracy, and further, there is a problem that it cannot cope with a pellicle frame of another shape at all. The present invention provides a method for manufacturing a pellicle which solves such a problem.

[0007]

According to the present invention, a pellicle film is bonded to a pellicle frame, and the unnecessary film is cut and removed by heating the pellicle frame along the outer periphery of the pellicle bonding surface using a laser. . Preferably, the laser is a YAG laser or a carbon dioxide laser.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is based on the fact that a pellicle frame is heated indirectly by heating a pellicle frame and thermally cut. Therefore, since the film can be cut at a relatively low temperature, it can be used under conditions where the laser output is stable. Further, since the film is cut along the outer peripheral portion of the frame by heating, high-precision positioning is not required. Since heat is used, there is no generation of foreign matter or abnormal cutting caused by the liquid as in the case of film cutting using a cutter or a solvent. Embodiments of the present invention will be described in more detail below. FIG. 1 is a schematic cross-sectional view of an unnecessary film cutting step of a pellicle film according to the present invention. In the present invention, for example, as shown in FIG. 1, a pellicle frame 4 on which an adhesive 3 is applied is adhered to a pellicle film 2 adhered to an outer frame 1. Next, the frame 4 is moved while irradiating the laser beam 6 with the laser 5 along the outer peripheral portion of the pellicle frame 4 bonded to the pellicle film 2 (hereinafter abbreviated as the outer peripheral portion of the frame).
Alternatively, the emission part of the laser light 6 may be moved along the outer peripheral part of the frame. At this time, the frame 4 absorbs the laser beam 6, generates heat, and heats the adhesive 3 and the pellicle film 2. As a result, the pellicle film 2 is softened, and the pellicle film is cut sharply as if a heated die cutter was pressed along the bonding end 7 where the film stress is concentrated.

Here, the present invention facilitates the control of energy during irradiation in the following points, as compared with the conventional method of directly cutting a pellicle film by a laser. In other words, the conventional laser cutting method converges the laser light at all wavelengths from near-infrared to ultraviolet to directly cut the pellicle film having high light transmittance, and extremely reduces the energy density on the irradiated surface. Needed to be higher. However, when the energy is too high, the pellicle film often evaporates and smokes to contaminate the pellicle film. Therefore, it is necessary to control the energy appropriately and irradiate a laser beam with energy that cuts the pellicle film without evaporation, but the width is extremely narrow, and the range is affected by slight laser output fluctuations and environmental changes. Will deviate. On the other hand, in the method of the present invention, a part of the pellicle frame is heated once, and is softened (thinned) by this heat, and the film is cut by the film tension, instead of directly cutting the film by laser light. It is. This has the advantage that the pellicle frame serves as a heat buffer for cutting, so that even if the laser output fluctuates or the environment changes, the energy for cutting the film is not significantly changed. Further, since the pellicle frame absorbs a larger amount of laser light than the pellicle film, the laser irradiation surface output for heating can be low.

The type of pellicle membrane to be cut and removed in the present invention is not particularly limited, and includes, for example, conventionally used nitrocellulose, cellulose acetate, cellulose propionate, amorphous fluoropolymer and the like. There is no particular limitation on the frame film adhesive used in the present invention as long as the necessary adhesive force can be obtained.
However, the film must be stable at a temperature at which the film is cut and removed by heating. Examples thereof include an epoxy-based adhesive, an acrylic-based adhesive, and an amorphous fluorine-based polymer. Also, the bonding method may be any of chemical bonding, physical bonding (thermal fusion, etc.). The pellicle frame used in the present invention is not particularly limited, but it is necessary that the pellicle frame does not deform or decompose when heated by a laser. Examples of such a material include aluminum alloy, stainless steel, iron, and ceramics, but the present invention does not particularly limit the material of the frame.

The laser used in the present invention is preferably a YAG laser or a carbon dioxide gas laser because it needs to be absorbed little by the pellicle film or the adhesive and absorbed by the pellicle frame surface. The average output to the irradiation surface is sufficient to be 5 W to 15 W because it is sufficient that the pellicle frame can be heated.

As a method of moving the pellicle frame or the laser beam to irradiate the laser along the outer periphery of the pellicle frame, there are a method of manually moving the frame or the laser emission port, and a method of mechanically moving the laser beam. In order to prevent foreign matter from adhering to the pellicle film and to ensure accurate positioning, it is preferable to move the pellicle film mechanically. As a method of mechanically moving the frame or the laser emission port, the pellicle frame is
A method of irradiating a laser from a fixed laser emission port on a YZ stage, a method of attaching a frame or laser emission port to the tip of a scalar robot, and a method of moving a frame or laser to the tip of a SAM (6-axis manipulator) There is a method of attaching an emission port.

[0013]

Next, the present invention will be described with reference to examples and comparative examples. Example 1 A fluororesin Teflon AF1600 (trade name, manufactured by DuPont, USA) was dissolved in a fluorosolvent Fluorinert FC-75 (trade name, manufactured by 3M, USA) to prepare an 8% by weight solution. Using this solution, a 0.8 μm thick transparent film was formed on a mirror-polished silicon substrate surface having a diameter of 200 mm and a thickness of 600 μm using a spin coater. Then
An outer frame of 200 mm x 200 mm x 5 mm in width and 5 mm in thickness is adhered on this film using an epoxy-based adhesive Aralditrapid (trade name, manufactured by Showa Polymer Co., Ltd.). Peeled off. Next, frame outer dimensions 100 mm x 100 mm
A pellicle frame made of an aluminum alloy and having a width of 5 mm and a frame thickness of 4 mm was adhered to the surface of the fluororesin film formed as described above, using an epoxy-based adhesive Aralditrapid (described above). The outer frame and the frame were attached to a fixing jig with the pellicle frame bonding surface facing upward and fixed so that the positions did not relatively shift. In addition, an XYZ automatic stage was separately prepared as a device for cutting the film, and the frame was fixed on the automatic stage together with a fixing jig. In addition, the exit of the YAG laser light conveyed by the optical fiber on the stage facing the pellicle frame,
The stage was fixed and arranged with a fixing jig different from the stage. Next, as shown in FIG. 1, a YAG laser beam 6 having a diameter of 0.5 mm is applied to the outer peripheral portion of the pellicle frame 4 so that the average output of the irradiation surface is 25 W
Irradiation. The stage (not shown) was moved at a moving speed of 10 mm / min in a previously programmed order so that the laser beam 6 was irradiated along the outer peripheral portion of the frame. By this operation, the pellicle film 2 was cut at the bonding end 7 of the frame 4 and an unnecessary film portion could be removed.

Next, foreign matter on the pellicle film obtained by removing the unnecessary film portion was measured in a dark room using a condenser lamp (400,000 lux). I was not able to admit. Next, the side surface of the pellicle frame was observed with a 10 × stereoscopic microscope, but no dripping of the liquid, no stains or adhesion of foreign matter was observed. In addition, the cut surface of the membrane was observed with a stereoscopic microscope at a magnification of 100 times, but no scratches or swelling were observed.

Comparative Example 1 Instead of irradiating a YAG laser beam in Example 1, a fluorine-based solvent was dropped to dissolve and remove an unnecessary film portion. That is, 0.3 mm from the upper part of the stage and the pellicle film
The tube tip of the tube type dispenser is set at the position of, and the stage is set so that the tube tip moves relatively along the frame, and the fluorine-based solvent Fluorinert FC-75 (described above) is supplied at 10 μl / min. While dropping, the unnecessary film portion outside the pellicle frame was cut and removed by moving along the outer peripheral portion of the frame. Observation of the obtained pellicle in the same manner as in Example 1 revealed no foreign substances of 0.3 μm or more on the film, no scratches on the cut surface of the film, and no swelling, but liquid on the side surface of the pellicle frame At five places, sagging and adhesion of foreign matter, which is considered to be a residue of the dissolved film, were observed.

Example 2 A 3% by weight solution of a resin solution obtained by dissolving a fluororesin Cytop CTX809SP2 (trade name, manufactured by Asahi Glass Co., Ltd.) in a fluorine-based solvent CT-SOLV.180 (trade name, manufactured by Asahi Glass Co., Ltd.) The procedure was performed in the same manner as in Example 1 except that Observation of the obtained pellicle in the same manner as in Example 1 revealed that any foreign substances having a size of 0.3 μm or more on the film, dripping of liquid on the side surface of the pellicle frame, adhesion of foreign substances, scratches on the cut surface of the membrane, and rising were all found. I was not able to admit.

Comparative Example 2 A 3% by weight solution of a resin solution obtained by dissolving a fluororesin Cytop CTX809SP2 (trade name, manufactured by Asahi Glass Co., Ltd.) in a fluorine-based solvent CT-SOLV.180 (trade name, manufactured by Asahi Glass Co., Ltd.) The procedure was performed in the same manner as in Comparative Example 1, except that the dripped fluorine-based solvent was CT-SOLV100 (trade name, manufactured by Asahi Glass Co., Ltd.). Observation of the obtained pellicle in the same manner as in Example 1 showed no foreign matter of 0.3 μm or more on the film, no scratches on the cut surface of the film, and no swelling, but on the side surface of the pellicle frame,
8 dripping of liquid and adhesion of foreign matter considered to be residue of dissolved film
It was recognized in some places.

[0018]

According to the present invention, it is possible not only to cut and remove a pellicle unnecessary film without generating dust, but also to obtain a pellicle free from stains on a pellicle film or a pellicle frame which has been generated at the time of cutting. became.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of unnecessary cutting of a pellicle film according to the present invention.

[Explanation of symbols]

 1 ‥‥ Outer frame 2 ク ル Pellicle film 3 ‥‥ Adhesive 4 ‥‥ Pellicle frame 5 レ ー ザ ー Laser 6 レ ー ザ ー Laser light 7 接着 Adhesive end

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03F 1/00-1/16

Claims (3)

(57) [Claims] 1. A pellicle film is adhered to a pellicle frame,
Lay the pellicle frame along the outer periphery of the pellicle bonding surface.
Method for manufacturing a pellicle, characterized by cutting and removing the unnecessary film by heating pressurized using users. 2. A method according to claim lasers are YAG laser
2. The method for producing a pellicle according to 1 . 3. The laser according to claim 1, wherein the laser is a carbon dioxide laser.
Item 4. A method for producing a pellicle according to Item 1 .