Proton beam micromachining on strippable aqueous base developable negative resist

Nowadays a significant amount of research effort is devoted to the development of technologies for the fabrication of microcomponents and microsystems worldwide. In certain applications of micromachining high aspect ratio (HAR) structures are required. However, the resist materials used in HAR technologies are usually not compatible with the IC fabrication, either because they cannot be stripped away or because they are developed in organic solvents. In the present work the application of a novel chemically amplified resist for proton beam micromachining is presented. The resist based on epoxy and polyhydroxystyrene polymers is developed in the IC standard aqueous developers. The exposed areas can be stripped away using conventional organic stripping solutions. In order to test the exposure dose sensitivity and the lateral resolution, various test structures were irradiated. Using this formulation 5-8 μm wide lines with aspect ratio 4-6 were resolved.