Improved Dry Etching Resistance of Electron-Beam Resist by Ion Exposure Process

The dry etching resistance of an electron-beam resist (PMMA) is successfully improved by P+ ion exposure prior to dry etching. The ion exposure increases resist stability by inhibiting pattern deformation and reducing resist thickness loss during dry etching. It changes the chemical structure of the resist polymer into another material which is stable to dry etch-ing. This technique is utilized for successful dry etching of 1 ~m hole patterns in MOS LSI manufacturing. Dry etching is needed for fine pattern fabrication in sol id-state device manufacturing. The resist used re-quires dry etching stabi l i ty for accuracy during the process. Most e lectron-beam resists are far less stable than photoresist, i.e., AZ1350J (1), and are not suitable for dry etching processes. Po lymethylmethacry late (PMMA) (2, 3), which has the highest resolution capacity for patterning geometries in the submicron line range, suffers from pattern deformation and muc