United States Patent 3,535,137
October 20, 1970

Method Of Fabricating Etch Resistant Masks
Ivan Haller
Michael Hatzakis
Rangaswamy Srinivasan

Filed January 13, 1967
Image of US PATENT 3,535,137

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 descriptions: cover graphic

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

 Citations [54]:
2,892,712 06/1959 Plambeck 2,895,891 07/1959 Miller 2,989,492 06/1961 Sanderson 3,196,008 07/1965 Mihajlov et al
National Museum of American History
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