Method for improved resolution of patterning using binary masks with pupil filters
AssigneeIntel Corporation
InventorsManish Chandhok, Brandon C. Barnett
Life of this patent
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Abstract
A photolithography lens system is disclosed. The system has several elements perpendicularly aligned to an optical axis. The elements include a light source that generates an exposing light, a first lens that has a front focal plane and a pupil plane, and a binary mask between the light source and the first lens. The binary mask is placed at the front focal plane of the first lens. A pupil filter is placed at the pupil plane. Finally, a second lens is provided that has a front focal plane at substantially the same position as the pupil plane. The second lens also has a back focal plane where a semiconductor wafer is placed.
Claims10
An apparatus comprising:
- a light source;
- 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=1−{[2(b−a)A1 sin c(kp(b−a)/2)cos(kp(a+b)/2)]/2a sin c(kpa)},
- where
- A1 is the transmission amplitude of said binary mask, λ is the wavelength of said exposing light, k=2Π/λ, a is one-half of a feature size of said binary mask, p is the pitch of said binary mask, and b=p/2;
- 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;
- and
- a substrate having photoresist thereon placed at the back focal plane of said second lens.
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 such that the combination of said pupil filter, said first lens, and said binary mask modify said exposing light to emulate the effect of an attenuated phase shift mask version of said binary filter and said first lens acting on said exposing light, said pupil filter is formed in accordance with:
- Pupil Filter=1−{[2(b−a)A1 sin c(kp(b−a)/2)cos(kp(a+b)/2)]/2a sin c(kpa)},
- where
- A1 is the transmission amplitude of said binary mask, λ is the wavelength of said exposing light, k=2Π/λ, a is one-half of a feature size of said binary mask, p is the pitch of said binary mask, and b=p2;
- 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;
- and
- a substrate having photoresist thereon placed at the back focal plane of said second lens.
A method comprising:
- forming a pupil filter in accordance with:
- Pupil Filter=1−{[2(b−a)A1 sin c(kp(b−a)/2)cos(kp(a+b)/2)]/2a sin c(kpa)},
- where
- A1 is the transmission amplitude of said binary mask, λ is the wavelength of said exposing light, k=2Π/λ, a is one-half of a feature size of said binary mask, p is the pitch of said binary mask, and b=p/2;
- placing a lens having a front focal plane and an image plane such that the front focal plane substantially coincides with said pupil plane;
- and
- placing a substrate having a photoresist thereon at said image plane.
Dependencies are inferred from the claim text.