Abstract
Contrast enhancement, wall profile control and sensitivity increase all are important factors for resists used in microlithography. The use of contrast enhancement layers is accompanied by a sacrifice of resist sensitivity and has been limited to application to positive type photoresists. SPACE process has been reported for a negative working electron beam resist. With a controlled UV-flood exposure, enhancements in both contrast and sensitivity of RD2000N resist have been obtained. However, its application is limited to a negative working resist.
The concept of SPACE may be expanded to other types of resists and lithographies such as positive working photoresists. I wish to present here contrast enhancement and resist wall profile control by photochemical surface crosslinkage. With addition of a crosslinking agent like an aromatic bisazide which has its UV absorption band far away from an imaging wavelength, one can obtain contrast enhancement, control of resist wall profiles and reduction of resist thickness loss during image development after photochemical surface crosslinkage.
There are several processes reported for maintaining resist wall profiles at high temperature. However, resist images thicker than 3μm tend to have surface reticulation after high temperature heating. Pulsed electron beam resist hardening solves this problem. Certain chemical treatments of resist images provide not only thermal flow resistance but also specific RIE resistance. These processes for maintaining resist wall profiles at high temperatures will also be presented.
