One of the most critical processing steps in the fabrication of integrated circuits is microlithography. The design of high density DRAMs requires the accurate patterning of submicron structures. The manufacturability of VLSI components can be greatly improved through the integration of computer aided design and simulation software with an advanced interferometric optical system. In a new approach, a typical line and space pattern with features as fine as 0.3 um has been produced using a mask that has both transmitting areas and reflective areas and 355 nm laser illumination.