Polymethylmethacrylate (PMMA) materials have been utilized for electron beam lithography for many years, offering high resolution capability and wide process latitude. Their poor sensitivity has, however, limited them until recently to R&D applications. MOSFET 0.25 im T-gate fabrication utilizing PMMA in a multi-layer system has caused an increase in the volume of resist used in commercial applications, prompting a need to evaluate formulations for optimum process performance. Results are presented from a study undertaken to evaluate resist casting solvent composition and molecular weight variation in PMMA for electron beam exposure. PMMA cast in several solvent systems have been evaluated for lithographic performance. Additionally, formulations in chlorobenzene with minor variations in molecular weight have beenevaluated for batch-to-batch uniformity. A 10 KeV MEBES electron beam system has been used to study resist sensitivity, contrast, and process latitude. Using a two-factor, three level factorial designed experiment, prebake and development time have been varied as controlled process factors. Samples with varying molecular weights were shown to have wide process latitude. These samples gave comparable performance while their molecular weights varied from 539K to 614K, and polydispersity varied from 3.3 to 6.1. Resist samples with chlorobenzene, PGMEA (propylene glycol monomethyl ether acetate) and anisole as the casting solvent resulted in equivalent performance.

Date of creation, presentation, or exhibit



Copyright 1994 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type

Conference Paper

Department, Program, or Center

Microelectronic Engineering (KGCOE)


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