JP2005189665A - Photomask - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve such problems that many kinds of substrates used for a photomask have tendency of easily charged, in particular, although quartz glass has extremely excellent optical characteristics, it is much easily charged as electric characteristics, and that when a photomask charged as described above is laid on a photoresist film, exposed and then separated from the photomask, the mask might induce electrostatic discharge and damage a chromium pattern formed on the photomask surface. <P>SOLUTION: The photomask has a light shielding film on the surface of a transparent substrate, the light shielding film formed into a pattern to shield a photoresist film against exposure. In this mask, a conductive transparent resin film is formed over the entire surface of the transparent substrate where the light shielding film is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photomask structure, and particularly relates to a photomask in which a light shielding film is not damaged.

  In a photolithography method used to manufacture a piezoelectric element used for a piezoelectric vibrator or a surface acoustic wave element, an image of a light-shielding pattern of a photomask having a light-shielding film is formed on a glass plate or a crystal on which a photoresist is formed. An exposure apparatus that projects and transfers onto a substrate such as a wafer is used.

  A photomask used in such an exposure apparatus is configured by forming an electrode pattern (mask pattern) with a highly light-shielding film on the surface of a mask substrate. As a material for forming this electrode pattern, chromium is generally used because it is easy to process a thin film and has high light shielding properties.

  Further, quartz glass is frequently used as a material for a substrate used for a photomask. Quartz glass has excellent characteristics such as low optical transmission loss, small optical performance degradation due to temperature, and suitable for use as a photomask with corrosion resistance and elastic performance. It has a feature that a fine pattern can be formed with high precision and that the pattern can be easily formed. In addition, fluorite etc. are used as another material of the board | substrate used for a photomask.

  Also, a pattern for forming a plurality of elements is usually formed on a single photomask, and a method for forming a large number of element patterns on a substrate such as a quartz wafer at a time multiple times with a single photomask. It is used.

  Regarding the photomask as described above, the following documents are disclosed.

JP-A-8-6234 JP-A-8-278625

  In addition, the applicant has not found any prior art documents related to the present invention by the time of filing of the present application other than the prior art documents specified by the above prior art document information.

  In the photolithography method, in order to accurately project the fine pattern formed on the photomask onto the photoresist film at the time of exposure, it is desirable that the surface of the photomask and the light shielding film pattern are brought into close contact with each other. When the light shielding film is peeled off, the outline of the pattern becomes unclear during exposure, and a pattern having a desired shape cannot be accurately projected onto the photoresist film.

  However, many substrates used for photomasks are easily charged. Quartz glass, in particular, has very good optical characteristics, but it is very easy to be charged due to its electrical characteristics, and a photomask in such a charged state is placed on the photoresist film and exposed to light. When the photomask is released, electrostatic discharge may occur, destroying the chromium pattern formed on the photomask surface.

  In addition, fine dust tends to be adsorbed on the surface of the charged photomask, which may cause problems during exposure. Furthermore, even if pattern destruction does not occur, the adhesion between the photomask surface and the light shielding film is weakened, and the light shielding film is partially peeled off from the photomask surface, so that the desired pattern shape cannot be obtained at the time of exposure. There are concerns about the occurrence.

  The present invention has been made to solve the above-described problems. In a photomask in which a light shielding film formed in a pattern pattern for shielding exposure to a photoresist film is formed on the surface of a transparent substrate, the light shielding film A photomask is characterized in that a transparent resin film is formed on the entire surface of a transparent substrate on which is formed.

  In addition, the transparent resin film described above is a resin film having conductivity, and the photomask is characterized in that the resin film is grounded.

  In the photomask according to the present invention, even when quartz glass that is easily charged is used for the photomask, the charge charged by the conductive resin film (ground connection) formed on the photomask surface on which the pattern is formed flows to the ground end. Because of this, electrostatic discharge does not occur even when the photomask is placed on the photoresist film and exposed to light after the photomask is separated from the photoresist film, and the chromium pattern formed on the photomask surface is not destroyed. .

  Further, since the charged electric charge is removed, dust is not adsorbed on the surface of the photomask, and there is no possibility of causing a problem during exposure. Furthermore, by forming the transparent resin film, the photomask surface and the light shielding film pattern can be in close contact with each other.

  Therefore, the photomask of the present invention has a significant effect on improving the reliability of the pattern formed on the photomask substrate and improving the yield by reducing the number of defective exposure products.

Hereinafter, an embodiment of a photomask according to the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view showing an embodiment of a part of a photomask according to the present invention. In FIG. 1, for clarity of explanation, a part of the structure is not shown, and some dimensions are exaggerated. The thickness dimension of each part is shown in a particularly deformed form to facilitate understanding of the present invention.

  That is, in FIG. 1, a light shielding film 12 made of metallic chrome having a thickness of about 100 nm on which a desired pattern is formed is formed on one main surface side of a plate-like quartz glass 11. Usually, the pattern of the light shielding film 12 is such that a plurality of device electrode patterns are formed at a time on a photoresist film, which will be described later. The light shielding film 12 is formed by a lithography method or a sputtering method. . As the substrate material, in addition to quartz glass, fluorite or quartz is used.

  A conductive transparent resin film 13 is formed on the entire surface of the quartz substrate 11 on which the light-shielding film 12 is formed by a spin coating method to constitute a photomask 10. The transparent resin film 13 is in electrical contact (connection) with an electrode (not shown) formed outside the exposed region on the surface of the quartz substrate 11, and this electrode is electrically connected to the ground terminal. The transparent resin film 13 is formed with a thickness of about several hundred nm, but it is desirable to form it as thin as possible. Further, as the formation method, other methods such as sputtering or CVD may be used.

  By forming the conductive transparent resin film 13 electrically connected to the ground end over the entire surface of the quartz substrate 11 on which the light shielding film 12 is thus formed, the charge charged on the photomask 10 is transferred to the transparent resin film. It is possible to discharge to the ground end via 13 and no unnecessary charge is stored in the photomask 10 body. Therefore, electrostatic discharge does not occur on the photomask, and various problems such as destruction of the light shielding film pattern caused by this discharge phenomenon can be eliminated. Further, by forming the transparent resin film 13 on the light shielding film 12, the light shielding film 12 can be adhered to the surface of the quartz substrate 11, and the light shielding film pattern can be prevented from being peeled off from the surface of the quartz substrate at the same time. .

  In the above embodiment, a conductive resin is used as the transparent resin film 13. However, when the substrate material of the photomask is made of a material that has low chargeability and hardly generates electrostatic discharge, The transparent resin film 13 does not need to be conductive, and by using a non-conductive transparent resin film, the light shielding film 12 can be brought into close contact with the surface of the quartz substrate 11, and the light shielding film pattern is peeled off from the surface of the quartz substrate. Is prevented.

FIG. 1 is a sectional view showing a part of an embodiment of a photomask according to the present invention.

Explanation of symbols

10, photomask 11, quartz substrate 12, light shielding film 13, transparent resin film

Claims (2)

In a photomask in which a light shielding film formed in a pattern pattern for shielding exposure to a photoresist film on the surface of a transparent substrate is formed,
A photomask comprising a transparent resin film formed on the entire surface of the transparent substrate on which the light shielding film is formed.   2. The photomask according to claim 1, wherein the transparent resin film is a conductive resin film, and the transparent resin film is grounded.

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