A Spatial Light Modulator for Optical Maskless Lithography

Photomasks for new integrated circuits with next generation design rules are increasingly more complex and costly, especially for development, prototyping, and eventual low volume production. Optical maskless lithography (OML) is a proposed alternative method in which the conventional photomask is replaced by a programmable reflective spatial light modulator (SLM) made up of many small mirrors [1]. Image contrast is formed by interfering 193 nm wavelength light via phase modulation of adjacent mirrors. Phase is controlled using either tilting or piston type mirrors [2, 3]. While SLMs are already being implemented for mask making [4], significantly smaller mirror size (