The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 21, 1994
Filed:
Aug. 21, 1992
Yaichiro Watakabe, Hyogo, JP;
Shuichi Matsuda, Hyogo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A photomask includes a transparent substrate, a light shielding film formed on the substrate, and a transparent film formed on the light shielding film and the substrate. The light shielding film has a bottom in contact with the substrate, a side face at an acute angle to the bottom, and an upper face in parallel with the bottom and at an obtuse angle to the side face. According to the light shielding film having such a configuration, a phase shift portion of a predetermined width and thickness can be formed accurately in the periphery of the light shielding film. The inferior influence of reflecting light with respect to the pattern resolution can be reduced if films of low reflectance are provided in the upper and lower portions of the light shielding film to improve the pattern resolution. The method of manufacturing this photomask includes the steps of patterning the light shielding film having a trapezoid configuration in which the upper base is shorter than the lower base on a transparent substrate, and forming a transparent film at a temperature of not more than 250.degree. C. on the substrate and the light shielding film. The thermal distortion in the light shielding film can be suppressed effectively by the formation of a transparent film.