Changes of Volume and Surface Compositions of Polymethylmethacrylate under Electron Beam Irradiation in Lithography

Abstract
The change of the content of oxygen and carbon in Polymethylmethacrylate (PMMA) under electron beam irradiation is investigated by Auger electron spectroscopy (AES) whereby we estimate the characteristic energy deposition of the decrement of oxygen to be 0.8–1.2×103 eV/nm3. It is also confirmed that cooling of PMMA considerably reduces the elimination rate of oxygen and that the decrement of the thickness of PMMA film under electron beam irradiation is closely related to the change of oxygen content. Moreover, it is shown that the PMMA alters from the positive resist to the negative resist as determined by observing thickness changes.