Optical error minimization in a semiconductor manufacturing apparatus
Provided are systems and methods for overcoming optical errors occurring from reticle and other hardware usage in a semiconductor fabrication apparatus. The systems and methods minimize optical errors, such as those resulting from gravitational sag on a reticle or mask, for a pattern being projected onto a wafer. The reduced errors allow larger reticles and masks to be used—while maintaining optical accuracy; and also improve optical budget management.
1. A reticle for transmitting light to produce a photolithographic image, the reticle comprising:
a holding portion that maintains the position of the reticle in a semiconductor fabrication apparatus;
a light transmission portion, comprising an opaque pattern, which permits light transmission capable of producing an image determined by the opaque pattern; and
wherein the reticle is constructed with a geometry that minimizes optical errors in the image occurring from reticle usage in the semiconductor fabrication apparatus said geometry including a substantially non-planar surface that compensates for deformations resulting from gravitational sag and wherein said reticle geometry compensates for non-linear and higher order light distortions associated a reticle chuck that holds the reticle.
2. The reticle of claim 1 wherein the holding portion comprises a peripheral edge of the reticle.
3. The reticle of claim 2 wherein the peripheral edge rests on a reticle stage.
4. The reticle of claim 1 wherein the light transmission pattern comprises an opaque material on a surface of the reticle that is proximate to a wafer.
5. The reticle of claim 4 wherein the reticle is constructed with an upward arc that compensates for deformation resulting from gravitational sag.