A simplified method for planarizing liquid-crystal-on-silicon (LCOS) backplanes is presented. The method relies on the planarizing capability of spin-cast benzocyclobutene (BCB) polymeric resin. BCB planarization shows a sixfold reduction in step height on the surface of a typical LCOS backplane. Contact with the underlying pixel circuitry is made by dry etching through openings in the BCB layer. Reflective metal (87% reflectivity) is deposited over the planarized surface and patterned to form high-aperture-ratio pixel mirrors (84%). An average resistance of 0.75 Ω per via was achieved with 3.6-µm-diameter vias in 2-µm-thick BCB. The method and the results of this LCOS backplane planarization and postprocessing are described.
© 1997 Optical Society of America
(070.4550) Fourier optics and signal processing : Correlators
(230.3720) Optical devices : Liquid-crystal devices
(230.6120) Optical devices : Spatial light modulators
(310.0310) Thin films : Thin films
Miller H. Schuck, Douglas J. McKnight, and Kristina M. Johnson, "Spin-cast planarization of liquid-crystal-on-silicon microdisplays," Opt. Lett. 22, 1512-1514 (1997)