For a range of thick film (3-15 mu m) photoresist applications, including MeV ion implant processing, thin film head (TFH) manufacturing, and microelectromechanical systems (MEMS) processing, there is a need for a low-temperature method for resist stabilization and curing. Traditional methods-of stabilizing or curing resist films have relied on thermal cycling, which may not be desirable due to device temperature limitations or thermally-induced distortion of the resist features. This study investigates the use of a flood electron beam system to achieve a non-thermal,: low temperature stabilization or cure of resist films. An electrostatic chuck (ESC) is also applied to the process to provide active cooling of the substrates. Electron beam processing techniques are applied to a range of resist products for a film thickness range of 3-10 mu m. Film properties are evaluated as a function of electron beam dose (mu C/cm(2)). Film shrinkage and index of refraction are monitored for all cure processes by ellipsometry. Chemical changes in the resist films are monitored by FTIR analysis. These changes are also evaluated via dissolution in developer, at low dose levels, and resistance to solvents at high dose levels. The dissolution in developer is found to increase with dose, between 10 and 100 mu C/cm(2), much like optical exposure, and decrease as cross-linking predominates at dose levels above approximately 200 to 250 mu C/cm(2). At high dose levels greater than 2500 mu C/cm(2) the resist becomes impervious to solvents such as acetone and NMP. Thus, the chemical changes in the resist films induced by the electron beam exposure can be correlated to dissolution or solvent resistance properties in the treated resist films. The thermal properties of the stabilized or cured films are monitored by thermal flow analysis, via SEM, and by TGA and DSC analysis. Significant improvement in the thermal flow stability is seen after electron beam processing, with features stable to above 300 degrees C. This is also detailed in the increase in the Tg of the resist films as seen in the TGA and DSC analysis.
