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:
May. 29, 2001
Filed:
Apr. 27, 1999
Nikon Corporation, Tokyo, JP;
Abstract
An illumination optical apparatus (IOA,) and an exposure apparatus (EA,) having same, that reduces coherence in the illumination light beam, which in turn eliminates illumination non-uniformities at the mask (,) and wafer (,). The illumination apparatus comprises, in order along an optical axis (AX), a coherent light source (,) capable of generating a first light beam (b,) having a coherence length, the light beam being directed along a first optical path. Further included is a depolarizer (,) and a first optical delay element (,). The latter is capable of splitting from the first light beam a second light beam (b,) which travels a delay optical path (DOP,) with a path length not less than the coherence length of the first light beam. The delay optical path returns to said first optical path at a deflection angle from said optical delay element. The illumination optical system may also include a plurality (i.e., second, third, etc.) optical delay elements or splitting delay stages (e.g.,,) having different path lengths.