Patent ID: 6567155
Filing Date: 2003-05-20
Classification: G03B,G03F

Abstract:
An apparatus comprising:a light source that generates an exposing light; a first lens placed perpendicular to an optical axis, said first lens having a front focal plane and a pupil plane; a binary mask placed perpendicular to said optical axis and between said light source and said first lens, said binary mask placed at said front focal plane of said first lens; a pupil filter placed perpendicular to said optical axis and at said pupil plane, said pupil filter formed in accordance with: Pupil Filter=1âˆ’{[2(bâˆ’a)A1 sin c(kp(bâˆ’a)/2)cos(kp(a+b)/2)]/2a sin c(kpa)}, â€ƒwhere A1 is the transmission amplitude of said binary mask, &lgr; is the wavelength of said exposing light, k=2Î /&lgr;, a is one-half of a feature size of said binary mask, p is the pitch of said binary mask, and b=p/2; and a second lens placed perpendicular to said optical axis, said second lens having a front focal plane at substantially the same position as said pupil plane, said second lens also having a back focal plane.