A new PSM system: SCAAM with Phase Phirst!

The Sidewall Chrome Alternating Aperture Mask (SCAAM), a next generation alternating Phase Shift Mask (alt-PSM) structure, has printed 70 nm semi-dense lines and offers the potential for low cost 100 nm imaging with 248 nm light. The SCAAM reticle production process etches the phase topography first and then forms transparent openings to define the image in a conformal chrome layer deposited afterwards. The Phase Phirst! system employs ready-to-write SCAAM blanks with regular pre-patterned surface topography, chrome and resist, eliminating the cost of writing a custom phase pattern on every plate. To use this type of mask, circuit designers would have to place every near-minimum-sized circuit feature (e.g.. gate) at a predefined phase-step location. Interconnections and larger features would be defined using the trim mask.