The paper presents a novel surface imaging resist, consisting of an anhydride-containing copolymer and a diazoquinone photoactive
compound (PAC). As base resin, alternating copolymers of styrene and maleic anhydride were prepared which show benefits such
as high glass transition temperature (Tg = 170 °C) or low deep-UV absorbance (0.12/pm at 248 nm), in addition to the simplicity
of synthesis with high yields.
After imaging exposure, the exposed areas are selectively silylated in a standard puddle development track at room temperature
within 90 to 120 s md. rinsing. The silylation is performed with an aqueous solution ofabis-aminosiloxane in water and a dissolution
promoter and is accompanied by a film thickness increase, the extent of which depends on several factors such as exposure dose,
PAC content in the resist, molecular weight of the base resin, aminosiloxane concentration and silylation time. The resist is
developed through reactive ion etching in oxygen plasma, giving negative tone patterns. Lateral structure deformation has not been
observed with this system since the resist is silylated far below the Tg of the base resin.
The use of suitable 2-diazo-1-naphthalenone-4-sulphonic acid esters as PAC and the absence of crosslinking during deep-UV
exposure offer the advantage that the same resist can be applied in the same mode (neg.) for i-line and KrF excimer laser lithography.
By this means, lines and spaces down to 0.4 pm and 0.3 pm were achieved in 2 pm thick resist after exposures with an i-line
(NA = 0.4) or KrF excimer laser stepper (NA =0.37), respectively.