Abstract
We performed micromachining of relatively thick siloxane films by proton beam writing (PBW) with beam energy of 1 MeV. The polydimethylsiloxane (PDMS) prepolymer films with a thickness of about 13 μm were spin-coated onto silicon substrates. After exposure to the 1-MeV proton beam (～1 μm in diameter), the samples were developed. The PDMS shows the behavior of negative resist and can be regarded as analog resist where the thickness of the structure gradually increases as a function of the proton beam (PB) fluence. Using this feature of the PDMS, we manufactured micro lenses with diameter of 40 μm by changing PB fluence. Micro-patterning of the PDMS films using scanning proton beam can offer a possibility of making three-dimensional structures for silica-based devices without baking and mask process.
