Advanced microstructure products by synchrotron radiation lithography

Abstract
Deep X-ray lithography using synchrotron radiation with a characteristic wavelength of about 1 - 3 Å is a powerful tool to generate threedimensional microstructures in thick layers of polymeric resists. Resist reliefs produced in this way are used in the framework of the so called LIGA process, as precise templates to generate microdevices from metals, plastics, ceramic materials, and glasses. A wide variety of applications exist for such microdevices in nearly all fields of modern technologies. Accordingly, development activities in LIGA microfabrication have been started worldwide. In the past few years materials and processes applied in deep X-ray lithography have been improved considerably. This includes the development of a new positive tone polymer resist and a new negative tone resist based on chemical amplification, thereby exceeding the sensitivity of poly(methylmethacrylate), the most often utilized resist material so far. By means of beryllium and diamond membranes ultraprecise X-ray masks have been realized. Advanced equipment has been developed which facilitates a good overlay accuracy for generating threedimensional microstructures by multiple irradiation processes. In addition, the subsequent replication steps of the LIGA process as well as the corresponding materials have been further improved and first LIGA devices are produced commercially.