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:
Dec. 19, 1995
Filed:
Feb. 24, 1994
Hiroyoshi Tanabe, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A projection exposure method in which a mask pattern containing both an isolated geometrical shape and closely arranged geometrical shapes can be improved in depth of focus. A central part in cross section of a beam of light is darkened prior to illumination of a mask. The beam of light thus darkened is projected to a photoresist film formed on a substrate through the mask and an optical projection system to carry out a first exposure. Next, at least one of the photoresist film and the optical projection system is relatively moved along an optical axis of the optical projection system, and then, the darkened beam of light is projected again to the photoresist film through the mask and the optical projection system to carry out a second exposure at a different position from that in the first exposure. A surface of the photoresist film is not in accordance with a focal plane of the optical projection system during the first and second exposures, respectively. The pattern of the mask is transferred on the photoresist film through the first and second exposures.