Radiation imagery chemistry: process – composition – or product th – Radiation modifying product or process of making – Radiation mask
Patent
1999-06-22
2000-10-03
Young, Christopher G.
Radiation imagery chemistry: process, composition, or product th
Radiation modifying product or process of making
Radiation mask
430 30, G03F 900
Patent
active
061270717
ABSTRACT:
A photolithographic mask for conducting illumination from a light source onto a semiconductor surface during a microlithographic manufacturing process. The mask includes a line end portion of a width w and including two corners, each corner defining a respective region for locating one or more serifs for correcting severe corner rounding and line end foreshortening effects caused by the optical diffraction during the optical imaging process. For aerial image/resist pattern modeled as a convolution or the square of a convolution between the photomask and an intensity/amplitude kernel function having an effective range r in x and y directions, and under a condition that w<r<2w, a hanging square serif of a size w.times.w is provided attached to a respective corner within a corner region. For the condition of 2nw<r.ltoreq.2(n+1)w, with n=1, 2, . . . , each corner region includes an associated (n+1) serifs, each being linearly aligned along line-end extension line and spaced apart from an adjacent serif by a distance w, with each of the first n serifs being square and of a width w, and the (n+1).sup.th serif being a rectangle of a length w and a width min(r-2nw, w). When the intensity/amplitude kernel function is modeled as being azimuthal-angle independent and being non-zero over a circular area of radius r, which is typical for usual circular aperture, the serif size in the corner regions may be optimized. For a hanging square serif of size w.times.w under the condition w<r.ltoreq.2w, if further w<r<.sqroot.2 w, then the hanging serif in each corner region may be reduced in size without altering the aerial image/resist pattern intensity at its respective corner. The portion of the square serif to be removed is that portion of the square which is outside the circular intensity/amplitude kernel function of radius r centered at its respective corner. For a set of associated (n+1) serifs under a condition 2nw<r.ltoreq.2(n+1)w, if further [(2n+1).sup.2 +1].sup.1/2 w.ltoreq.r .ltoreq.2(n +1)w, with n=1, 2, . . . , then the (n+1).sup.th serif in each corner region may be reduced in size without altering the aerial image/resist pattern intensity at its respective corner. The portion of the (n+1).sup.th serif to be removed is that portion of the rectangle which is outside the circular intensity/amplitude kernel function of radius r centered at its respective corner.
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International Business Machines - Corporation
Sabo, Esq. William D.
Young Christopher G.
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