Use of chromeless phase shift masks to pattern contacts

摘要

Method for using chromeless phase shift lithography (CPL) masks to pattern contacts corresponding CPL masks. The method for patterning contacts includes illuminating a CPL mask comprising a reticle having plurality of phase-shifting features interspersed with non-phase-shifting areas with a short wavelength light source, wherein the phase-shifting features are configured in a pattern corresponding to a target pattern of the contacts on the semiconductor substrate. Phase-shifted and non-phase-shifted light passing through the reticle is the projected as an aerial image onto a layer of a negative tone resist applied over the semiconductor substrate to pattern the contacts in the resist. The phase-shifting features may comprise recesses or mesas, and cause light passing therethrough to be phase-shifted in phase approximately 180° from light passing through non-phase-shifting areas of the mask.