Antiferroelectric liquid crystal on silicon

Tristate antiferroelectric and v-shaped liquid crystal materials have recently offered the promise of both the fast switching of ferroelectric materials and the analogue switching of nematic materials at drive voltages compatible with those available from standard CMOS technology thereby making them, at least in principle, suitable for consideration in microdisplay and other photonic applications. AFLC development is in its early stages and the materials are not yet mature enough for widespread commercial use. The object of the ESPRIT funded MINDIS project has been to evaluate AF-LCoS technology. The electro-optical characteristics of a number of experimental materials have been experimentally measured in test cells that emulate the situation of a silicon backplane (e.g., aluminum reflective back electrode etc). Some candidate materials been shown to exhibit high contrast, uniformity and repeatability. A CMOS active matrix backplane with 1000 line resolution has been designed and fabricated. The backplane is capable of operating in digital or analogue modes for FLC and AFLC respectively. Planarization techniques have been applied to the CMOS wafers but planarization has been shown to be more problematic than with previous backplanes. The reasons for this are discussed. The technology has been theoretically evaluated for use in microdisplays for both projection and near-to-eye applications.