Abstract of the Disclosure

A method for manufacturing electron beam degradable, etch resistant, positive resist masks from vinyl-type polymers and copolymers in which one-half the carbon atoms of the main chain are quaternary such as polymethyl methacrylate or cellulose derivatives such as cellulose acetate, the masks being formed into a thin film and portions of the film being exposed to electron beam irradiation to reduce the average molecular weight of the irradiated portions. Prior to irradiation the polymer film is baked to improve adhesion and handling characteristics. After exposure, the portions of reduced average molecular weight are developed by an in situ fractionation step which dissolves only the portions of reduced molecular weight. Subsequently, the developed polymer is subjected to a baking step for a time sufficient to eliminate undercutting resulting from the lateral spreading of radiation during exposure, thereby improving the resolution of the resist. Etching of an underlying substrate is then undertaken with a desired etch.

• Figure 1 is a flow chart diagrammatically outlining the principal method steps for fabricating a high resolution positive resist mask.

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