Proton Beam Writing

Abstract

Proton beam writing (PBW) is a mask-less 3D structuring method that uses a focused, relatively high energy Proton beam, followed by an etching step to create free standing 2D and 3D structures in a large variety of target materials. During the irradiation step, defects are created locally in the target material that influence the etching behavior of the second step. The flexibility, high resolution and ability to perform rapid prototyping of micro-electro-mechanical systems makes PBW an interesting area of investigation. However, producing 3D structures reliably and predictably as well as limited theoretical understanding of many of the complicated aspects of PBW are some of the challenges that PBW faces. This work extends the knowledge of this complicated process in many key areas, including the stopping (slowing down and radiation damage) of fast particles in matter and the etching of the final 3D structures. For this new models are developed, simulations are performed and key experiments are used to test and improve the new approaches. New aspects of the etching process during PBW of Gallium Arsenide are also uncovered and discussed. Further more, progress on many practical aspects of PBW was made. These include ion beam optics optimization, beam-line design, target design and accelerator upgrades to the accelerator facilities in Göttingen. Additionally, new software tools for PBW were also developed and employed successfully.