Scanning thermal lithography: Maskless, submicron thermochemical patterning of photoresist by ultracompliant probes

This article introduces a scanning probe lithography technique in which ultracompliant thermal probes are used in the selective thermochemical patterning of commercially available photoresist. The micromachined single-probe and multiprobe arrays include a thin-film metal resistive heater and sensor sandwiched between two layers of polyimide. The low spring constant (<0.1 N/m) and high thermal isolation provided by the polyimide shank is suitable for contact mode scanning across soft resists without force feedback control. The probes provide what is effectively a spatially localized postexposure bake that crosslinks the photoresist in the desired pattern. rendering it insoluble in developer. For 450-nm-1400-nm-thick AZ5214E (Clariant Corp.). line and dot features with sizes of 450-1800 nm can be printed using probe powers of 13.5-18 mW. and durations of 1-60 s per pixel. Variation of feature sizes with process parameters is described. (C) 2004 American Vacuum Society.