Agglutinat for pellicle, a pellicle using it and a method for evaluating pellicle
09703188 ยท 2017-07-11
Assignee
Inventors
Cpc classification
G03F1/64
PHYSICS
International classification
G03F1/64
PHYSICS
Abstract
A pellicle is proposed in which the agglutinant layer which enable the pellicle to be adhered to a photomask is doped with a mechanoluminescent material so that the uniformness of the thickness of the agglutinant layer can be confirmed, when the pellicle is adhered to the photomask, by observing visually or by CCD camera for any irregularity in the pattern of the light emitted from the agglutinant layer.
Claims
1. An agglutinant for pellicle for binding the pellicle to a photomask, characterized in that said agglutinant contains a mechanoluminescent material.
2. The agglutinant for pellicle as claimed in claim 1, wherein said mechanoluminescent material emits a light with a strength commensurate with a magnitude of a stress imparted to it.
3. The agglutinant for pellicle as claimed in claim 2 wherein said mechanoluminescent material is strontium aluminate-based material which is activated by containing europium (Eu) ion as a luminescent ion.
4. The agglutinant for pellicle as claimed in claim 1 wherein a main ingredient of said agglutinant is a silicone composition.
5. The agglutinant for pellicle as claimed in claim 1 wherein a main ingredient of said agglutinant is an acrylic composition.
6. The agglutinant for pellicle as claimed in claim 1 wherein a dosage of said mechanoluminescent material is 50 through 1,000 mass parts as opposed to 100 mass parts of said agglutinant.
7. A pellicle comprising a pellicle frame, a pellicle membrane which is tensely adhered to one annular face of said pellicle frame, and an agglutinant layer laid on another annular face of said pellicle frame for enabling said pellicle to be adhered to a photomask, wherein said agglutinant layer contains a mechanoluminescent material.
8. The pellicle as claimed in claim 7 wherein said mechanoluminescent material emits a light with a strength commensurate with a magnitude of a stress imparted to it.
9. The pellicle as claimed in claim 8 wherein said mechanoluminescent material is strontium aluminate-based material which is activated by containing europium (Eu) ion as a luminescent ion.
10. The pellicle as claimed in claim 7 wherein a main ingredient of said agglutinant layer is a silicone composition.
11. The pellicle as claimed in claim 7 wherein a main ingredient of said agglutinant layer is an acrylic composition.
12. The pellicle as claimed in claim 7 wherein a dosage of said mechanoluminescent material is 50 through 1,000 mass parts as opposed to 100 mass parts of said agglutinant.
13. A method for evaluating a pellicle characterized in that when said pellicle which contains a mechanoluminescent material in its agglutinant layer is adhered to a photomask via said agglutinant layer, a strength of light emitted from said agglutinant layer is inspected.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1)
EXAMPLES TO EMBODY THE INVENTION
(2) Here the present invention is explained in greater detail with reference to the drawing, and one should not construe the invention to be limited to the example or the drawing.
(3)
(4) As shown in
(5) It is noted that, in the present invention, there are no limitations to the materials of which the pellicle membrane or pellicle frame are made, and it is possible to use any conventionally known materials, but from the viewpoints of rigidity and the machinability, the pellicle frame is preferably made of metal. The pellicle membrane may be adhered to the pellicle frame in any known method.
(6) In the pellicle of the present invention, the agglutinant of the present invention is laid on the lower annular face of the pellicle frame in a manner such that the resulting agglutinant layer has a predetermined width (normally equal to or smaller than the width of the frame bar) and such that it enables the entirety of the lower annular face of the pellicle frame to be adhered to a photomask (glass base plate).
(7) As is explained above, the agglutinant for pellicle of the present invention is doped with a mechanoluminescent material, but the base agglutinant can be selected from known agglutinants. Especially silicone agglutinant consisting mainly of silicone composition and acrylic agglutinant consisting mainly of acrylic composition are preferable.
(8) Examples of the silicone agglutinant that can be used as the base agglutinant include X-40-3122, KR-3700, X-40-3103, and X-40-3264 (all commercial products of Shin-Etsu Chemical Co., Ltd.).
(9) Examples of the acrylic agglutinant that can be used as the base agglutinant include SK-1425, SK-1495 and the like of SK Dyne series (all commercial products of Soken Chemical & Engineering Co., Ltd.).
(10) Among the above-named silicone agglutinants, X-40-3122 (commercial product of Shin-Etsu Chemical Co., Ltd.) is preferable because it is high in adhesion strength and contains less low molecular weight siloxanes. Also, among the above-named acrylic agglutinants, KS-1495 (commercial product of Soken Chemical & Engineering Co., Ltd.) is preferable because it is high in adhesion strength and operability.
(11) The mechanoluminescent material with which the agglutinant for pellicle of the present invention is doped is not limited so long as it emits light in response to stress; but a preferred material is a strontium aluminate which is activated by containing europium (Eu) ion or an europium compound as the source of europium ion. Strontium aluminate is a compound represented by a formula:
Sr.sub.xAl.sub.yO.sub.z (0<x,0<y,0<z);
and examples of this include SrAl.sub.2O.sub.4, SrAl.sub.4O.sub.7, Sr.sub.4Al.sub.14O.sub.25, SrAl.sub.12O.sub.19, and Sr.sub.3Al.sub.2O.sub.6. Strontium aluminate can be obtained through a reaction between alumina and strontium.
(12) Examples of alumina include alumina, alumina, alumina, alumina, alumina, alumina, alumina, and alumina. Among these, alumina, alumina and alumina are preferable to use.
(13) Choice for the strontium compound is not specially limited, and its examples include strontium carbonate, strontium oxide, strontium hydroxide, strontium halide, strontium sulphate, strontium nitrate, and strontium hydrogen phosphate.
(14) The europium compound is not limited either, and it can be europium carbonate, europium oxide, europium chloride, europium sulphate, europium nitrate, or europium acetate.
(15) The method for making the mechanoluminescent material is not specially limited; an example is to first cause an alumina to react with a strontium compound to thereby obtain strontium aluminate, which is then added, together with a europium compound, to water and/or organic solvent where they are mixed together, and then to remove the water and/or the organic solvent, and to bake and pulverize the remnant solid matter into power or the like.
(16) When a stress is imparted to this mechanoluminescent material, the part of it where the stress is imparted emits green light with a strength commensurate with the magnitude of the stress. The higher the concentration (dosage rate) of the mechanoluminescent material in the agglutinant is, the higher the agglutinant's light emission responsive becomes, but if the dosage of the mechanoluminescent material exceeds 1,000 mass parts against 100 mass parts of the base agglutinant, which is a raw material for the agglutinant for pellicle of the present invention, it becomes impossible to knead the mechanoluminescent material into the base agglutinant; on the other hand, if the said dosage is less than 50 mass parts, the light emission responsive to the stress becomes too weak to enable observation of the emitted light amount. Therefore, the dosage of the mechanoluminescent material is preferably 50 through 1,000 mass parts against 100 mass parts of the base agglutinant.
(17) Also, it is acceptable to add different additives to the agglutinant for pellicle of the present invention, for different purposes, to extents that would not thwart the effects of the present invention. Examples of such additives include parting agent, pigment, dye, plasticizer, flame retardant, heat resistance improver, weather resistance improver, thixotropy imparting agent, antibacterial agent, and anti-mold agent.
(18) Most of the above-mentioned mechanoluminescent materials are in powder form so that on occasions it is difficult to dispense the material uniformly in the base agglutinant. On such occasions, it is possible to disperse the mechanoluminescent material in a solvent and then add the solution to the base agglutinant; the possible solvents are such as an aromatic solvent like toluene and xylene, or an aliphatic solvent such as hexane, octane, isooctane, and isoparaffin, or a ketones solvent such as methyl ethyl ketone and methyl isobutyl ketone, or an ester solvent such as ethyl acetate and butyl acetate, or ethers solvent such as diisopropyl ether and 1,4-dioxane, or a mixture of any of these.
(19) The application of the agglutinant for pellicle to the pellicle frame 12 is done by first diluting the agglutinant in a solvent, if necessary, and then laying the solution onto the lower annular face of the pellicle frame 12. Then by drying the agglutinant with heat and curing it, an agglutinant layer 13 is completed. The method for applying the agglutinant for pellicle can be brush painting, spraying, automatic dispensing, and the like.
(20) The releasing layer (separator) 14 is for the protection of the agglutinant layer 13 until the pellicle is adhered to the photomask, and hence it is removed before the pellicle is used. For this reason, the releasing layer (separator) is used only in the case where the agglutinant layer is not protected by anything else during the time until the pellicle is adhered to the photomask. The product pellicle is distributed in the market generally in the form in which the releasing layer (separator) is attached to the agglutinant layer. Choice of the material for the releasing layer (separator) 14 is not limited, and can be made from anything known as a separator. Also, the releasing layer (separator) can be adhered to the agglutinant layer by any known tape adhesion method.
(21) The pellicle having the agglutinant layer for pellicle of the present invention not only works as a regular dust-fender for the photomask, but also allows a simple and effective detection of the ups and downs and heaving of the agglutinant layer since it is possible to observe, from the backside of the glass plate photomask, the pattern of stress-responsive light emission from the agglutinant layer, after the pellicle is adhered to the photomask.
(22) According to the evaluation method of the present invention, it is possible to observe visually the presence and strength of the light emitted from the agglutinant layer, so that the evaluation of the ups and downs and heaving of the agglutinant layer has become simpler and more accurate compared to the conventional pellicle which uses an agglutinant which does not contain mechanoluminescent material.
(23) Furthermore, since it is possible to measure the luminescence area and luminescence amount by means of CCD camera and an image processing equipment, the degrees of the ups and downs and heaving of the agglutinant layer can be evaluated quantitatively; as a result, it is possible to set a clear evaluation standard for the agglutinant layer formed on the pellicle, and also a highly accurate and reliable evaluation which is not affected by difference in inspectors' skills is attained
EXAMPLES
(24) Herein-below, the present invention will be explained in detail with reference to examples; however the scope of the present invention is not limited by the examples.
Example 1
(25) Firstly, a pellicle frame made of an aluminum alloy [external size: 149 mm (long side); 122 mm (short side); 5.8 mm (height); 2 mm (bar width)] was brought in a cleanroom, and after being thoroughly washed with a neutral detergent and pure water, it was dried.
(26) Meanwhile, an agglutinant for pellicle was prepared by mixing 100 mass parts of silicone agglutinant X-40-3122 (a commercial product of Shin-Etsu Chemical Co., Ltd.) with 100 mass parts of a mechanoluminescent material ML-032 (a commercial product of Sakai Chemical Industry Co., Ltd.), which is a strontium aluminate-based material activated by its content of europium (Eu) ion as the luminescent ion. Then the thus prepared agglutinant was applied to the lower annular face of the pellicle frame using an automatic dispenser (manufactured by Iwashita Engineering Co., Ltd.).
(27) Next, the agglutinant was dried by air until it lost fluidity and then the pellicle frame was heated to 130 degrees C. whereby the agglutinant was cured and formed an agglutinant layer.
(28) A pellicle membrane was adhered to the upper annular face of the pellicle frame via an adhesive named CYTOP CTX-A (a commercial product of ASAHI GLASS CO., LTD.), and excessive part of the pellicle membrane extending beyond the pellicle frame was trimmed off with a knife cutter, whereby a pellicle was completed.
Example 2
(29) A pellicle was manufactured in the same manner as in Example 1 except that the agglutinant was prepared by mixing 100 mass parts of acrylic agglutinant SK-1495 (a commercial product of Soken Chemical & Engineering Co., Ltd.) with 100 mass parts of a mechanoluminescent material ML-032 (a commercial product of Sakai Chemical Industry Co., Ltd.).
Comparative Example 1
(30) A pellicle was manufactured in the same manner as in Example 1 except that the agglutinant used was X-40-3122 (a commercial product of Shin-Etsu Chemical Co., Ltd.) but no mechanoluminescent material was added to it.
Comparative Example 2
(31) A pellicle was manufactured in the same manner as in Example 1 except that the agglutinant used was SK-1495 (a commercial product of Soken Chemical & Engineering Co., Ltd.) and no mechanoluminescent material was added to it.
(32) [Observation of Adhesion Quality of Agglutinant Layer]
(33) The pellicles as obtained in Examples 1, 2 and Comparative Examples 1, 2 were respectively adhered to that face of a glass plate in which a lithography pattern was formed, and their agglutinant layers were inspected for their quality of adhesion visually as well as using a CCD camera in the following manners (Observations 1, 2). 1. Visual observation of the quality of adhesion under a fluorescent lamp: In a cleanroom under a fluorescent lamp, that face of the agglutinant layer by which the adhesion was effected was observed visually from the back side of the glass plate to which the pellicle was adhered; in particular the presence or non-presence of the emitted light and the strength of the emission were confirmed. 2. Observation of the quality of adhesion by CCD camera: Under the same conditions as above, that face of the agglutinant layer by which the adhesion was effected was observed from the back side of the glass plate to which the pellicle was adhered by means of a combination of a CCD camera and an image processing equipment (IV series, CV-X100 series; both commercial products of Keyence Corp.); in particular the presence or non-presence of the emitted light and the strength of the emission were confirmed.
(34) It is noted that in the above Observations 1 and 2, in order to create a situation where the quality of the adhesion of the agglutinant layer to the glass plate is bad as well as a situation where said quality is good, the manner of adhering the agglutinant layer was intentionally controlled. Therefore, observation was conducted on both the situation where there were no ups and downs or heaving in the agglutinant layer (adhesion of high quality) and the situation where there were ups and downs or heaving (adhesion of poor quality), and the observation results were rated in the following standards. The rated results are shown in Table 1.
(35) (Evaluation Standards)
(36) Excellent: it was possible to evaluate quantitatively the ups and downs or heaving of the agglutinant layer under a predetermined condition. Good: it was possible to visually detect the presence of the ups and downs or heaving of the agglutinant layer, so that evaluation of the quality of the adhesion is possible to a reasonable extent. Bad: it was not possible to visually detect the presence of the ups and downs or heaving of the agglutinant layer, so that evaluation of the adhesion quality was not possible.
(37) TABLE-US-00001 TABLE 1 Comparative Example Example 1 2 1 2 Visual Inspection adhesion of Good Good Bad Bad high quality adhesion of Good Good Bad Bad poor quality by CCD camera adhesion of Excellent Excellent Bad Bad high quality adhesion of Excellent Excellent Bad Bad poor quality
(38) As can be seen from the results entered in Table 1, the agglutinant for pellicle of the present invention or the pellicle which uses it enables simple and accurate evaluation of the quality of the adhesion of the agglutinant layer, because, by linking the strength of the light emitted from the agglutinant layer to the magnitude of the stress that it has received at the time of the adhesion of the pellicle to the glass plate, it is possible to know the existence or non-existence of the ups and downs or heaving of the agglutinant layer.
REPRESENTATION OF REFERENCE NUMERALS
(39) 1: pellicle 11: pellicle membrane 12: pellicle frame 13: agglutinant layer (agglutinant containing mechanoluminescent material) 14: releasing layer (separator)