<title>Deep ion-beam lithography for micromachining applications</title>

LIGA and its defining process deep x-ray lithography, is an important method for machining high-aspect ratio microstructures, and a diverse range of applications are presently being investigated. One limitation of the technique is associated with the restriction on the 3D shape of the machined structures to essentially prismatic geometry. Further technical problems concerning the fabrication of a suitable mask for deep x-ray lithography are associated with the limited thickness of resist which can be patterned using electron beam lithography, and the undesirable exposure of resist by secondary radiations in an intervening x-ray lithography step which is used to produce a thicker mask. A deep lithography process using a focused beam of high energy light ions has the potential to overcome many of the geometrical restrictions inherent in deep x-ray lithography. An alternative use of deep ion bema lithography is to pattern a thick resist layer for the production of masks for deep x-ray lithography. This paper reports progress on the development of a system for deep ion bema lithography using a scanned 2.0 MeV proton beam of approximately 1 micron diameter. The result of computer simulations of the capabilities of deep ion beam lithography for the fabrication of thick DXL masks is presented.