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 SiO2 layers that are patterned by a 193nm wavelength scanner to dimensions as small as 150nm. 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 1nm precision, which is adequate for defining 50nm features lithographically. Transient response measurements show that one version of the SLM responds to actuation as quickly as 20μs, fast enough for current 193nm wavelength excimer laser sources.

Photolithography system with liquid crystal display as active gray-tone mask for 3D structuring of photoresist

“…Maskless lithography that utilizes a liquid crystal device (LCD) or a digital micromirror device (DMD) [5,6] as an electrically controllable spatial light modulator (SLM) has been developed in order to simplify the conventional photolithography [7][8][9][10]. A computer-generated photomask serves as a reconfigurable mask in the lithography system.…”

MEMS thermal imager with optical readout

“…In essence a diffraction grating was formed by the pixels themselves. Image formation using electro-statically controlled piston-only mirrors and similar optical techniques to control the phase of the reflected light have been explored before [25][26][27][28]. There are several methods to form the interference array, and these will be discussed shortly.…”

“…If this were indeed possible, it would also eliminate the extensive, and therefore costly, calibration procedures necessary for other technologies such as bolometers. The purpose of this paper is to report on our progress in coupling our expertise in spatial light modulator design [25][26][27][28][29] with thermally actuated MEMS cantilevers to work towards a direct-view readout technology.…”

Opportunities in uncooled infrared imaging: A MEMS perspective

“…Given our expertise in silicon-based MEMS technology, and in particular on spatial light modulators [1,2,17,22], we focused our fabrication efforts in the first area. In this paper, we will specifically describe our efforts to create prototypes of a "direct-view" sensor based on MEMS cantilever technology.…”