Design and process of a new DUV ARCH3 resist

A new concept for polymer design is described which can extend the utility of acetal chemistry in the development of advanced chemically amplified deep-UV resists for KrF excimer lasers. Many acetal blocked polymers only impart marginal thermal flow properties to the photoresist matrix. This polymer design concept can overcome this thermal flow deficiency and also improve photoresist contrast and resolution. This concept involves the formation of crosslinked acetal polymers from linear acetal blocked polymers via acid labile crosslinks. The resulting branched polymers have increased T g and therefore impart improved thermal flow properties to the resist. Furthermore, the acid lability of the crosslinks results in a large molecular weight differential between exposed and unexposed areas of the resist leading to larger dissolution rate discrimination between exposed and unexposed regions. The ultimate result is improved resolution capability of the resist system. This design concept has been incorporated into the ARCH3 resist series.