Spatial light modulator for maskless optical projection lithography

Abstract

Spatial light modulators (SLMs) designed to replace photomasks for optical lithography have been designed, fabricated, and tested. These microelectromechanical devices are fabricated with alternating polycrystalline Si and sacrificial $\mathrm{Si}{\mathrm{O}}_2$ layers that are patterned by a $193\mathrm{nm}$ wavelength scanner to dimensions as small as $150\mathrm{nm}$ . Aerial image simulations were used to define the mechanical requirements of the devices. Piston motion of electrically actuated devices was measured with an optical profilometer. The measurements were fit to a simple equation to within $1\mathrm{nm}$ precision, which is adequate for defining $50\mathrm{nm}$ features lithographically. Transient response measurements show that one version of the SLM responds to actuation as quickly as $20\mu \mathrm{s}$ , fast enough for current $193\mathrm{nm}$ wavelength excimer laser sources.