Lithography resolution capability

Dry etch resistance, as well as sensitivity and resolution capability, has become one of the most important factors for resist materials for microfabrication. Much effort has been made to develop resist materials which meet severe requirements for lithography and processes needed in VLSI fabrication, and many resist materials have been reported so far. 

FIGURE 16.7 Pattern cut in a polymer resist using x-ray lithography, showing the steep edges and resolution capable with this technique. (From Hoechst High Chem. Magazine, 1989. With permission.)... 

A chemically amplified, positive-working resist system based on silylated polyhydroxystyrene has shown its capability for application to quarter micron lithography. The present paper describes the recent improvement in the resist performance achieved through studies on polymer characteristics and process conditions. Possible measures to suppress a peculiar problem of positive-working chemical amplification systems, i.e., formation of T-shaped profile, is also presented. Although the development is still on the way, the silylated polyhydroxystyrene based resist tem shows excellent properties on resolution capability, sensitivity and process latitude. 

MUV lithography where exposure is based on the 313 nm mercury emission, is a relatively mature technology. The resolution enhancement that accrues from a shift to the MUV region has been carefully documented (69) and MUV projection printers are commercially available at this time. These include the Perkin Elmer Micralign series 300 and 500 both of which have MUV capability. 

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