Abstract: A method for fabricating a mask for patterning a radiation sensitive layer in a lithographic printer is disclosed. An attenuating (absorptive or reflective) layer is coated over a substantially transparent base substrate such that after processing a two-dimensional spatially varying attenuating pattern is created with a continuously or discretely varying transmission or reflection function. In accordance with the present invention the two-dimensional attenuating pattern is formed by e-beam patterning of radiation sensitive layer to create a three-dimensional surface relief pattern. This pattern is transferred to the attenuating layer by an anisotropic etch, typically a directional reactive plasma etch. The attenuation of this radiation absorbing or reflecting layer varies with layer thickness. In one embodiment of this invention the attenuation of the mask would vary spatially in a continuous manner.

Abstract: Multilayer film stacks and gray scale processing methods are employed for fabricating phase-shifting masks (PSMs) utilized in lithography. Desired optical transmission and phase-shifting functions of the mask are achieved by controlling the optical properties and thickness of constituent film layers. The mask can be tuned for optimal performance at various wavelengths to an extent beyond that obtainable using a single layer film to control both attenuation and phase shifting of incident light. The processing methods exploit multi-level electron beam or optical beam lithography techniques, and the etch selectivity afforded by selection of appropriate materials for the film stack, to obtain improved yields and reduced processing costs for fabrication of PSMs. In particular, diamond-like carbon (DLC) materials formed by ion beam deposition and having a stress of 1 GPa or less are utilized as etch stop layers.