DEEP ULTRAVIOLET PATTERNING OF MONOLAYER FILMS FOR HIGH-RESOLUTION LITHOGRAPHY

A new process has been developed for high resolution photolithography that employs chemisorbed monolayer films as the surface imaging layers. Organosilane treated surfaces are exposed to patterned deep UV radiation, either from excimer laser or lamp sources. The photochemical process modifies the surface wettability and reactivity of the film. Organosilane films patterned by deep UV radiation are treated with a Pd/Sn catalyst and then metallized with electroless copper and nickel baths to yield metal films several 100 angstrom thick. The metal is selectively deposited in the unexposed regions of the film to produce a positive tone image. The patterned metal film is then utilized as a plasma hard etch barrier in a reactive ion etch, allowing efficient pattern transfer into the underlying substrate and producing features with linewidths to 0.4-mu-m. Electrical testing of processed substrates demonstrates compatibility of the process with subsequent device performance, and working transistor test structures have been fabricated. Decoupling the imaging (monolayer surface imaging layer) and resist (metal film) functions of a photoresist allows separate optimization of each function in this scheme. The patterning process is very general and may be applied to a variety of substrate types. Other potential applications include patterned wettability and reactivity of surfaces for selective attachment of other species such as fluorophores or biological moieties.