Molecular parameters and lithographic performance of poly(glycidyl methacrylate-co-ethyl acrylate): A negative electron resist

Abstract

To facilitate the production of a polymeric electron resist of consistent quality we must know how molecular parameters are related to lithographic performance. Previous work has indicated that for negative resists in general, sensitivity and contrast increase with increasing molecular weight and decreasing polydispersivity, respectively. We describe experiments on eight batches of a particular resist, poly(glycidyl methacrylate-co-ethyl acrylate) [P(GMA-co-EA)], which compare lithographic performance, in terms of sensitivity, contrast, and edge sharpness, with molecular weight (Mw), molecular content (%GMA), and polydispersivity (Mw/Mn). The earlier conclusions are borne out. To achieve a sensitivity of 4×10−7 C cm−2 at 10 kV and a contrast of about 1.0 (the latter being needed for lithography for chromium photomask production), the required values for this resist of Mw, %GMA, and Mw/Mn are, respectively, ?1.6×105, 70±2, and ?3.0.