P-LIGA: 3D-integration of microstructures with curved surfaces by deep ion irradiation

Using the advantage that the projected range of ions in matter is sharply limited, a new technique for the production of three-dimensional microstructures has been developed. Based on the P-LIGA technique (Proton-Lithographie, Galvanoformung, Abformung) this process allows the generation of structures with surfaces of almost any shape having a root mean square roughnesses of about lambda/50 for visible light wavelengths. An ion beam with diameters between 2 and 50 mu m is directly writing the structures and the shape is varied by geometrical manipulation of the sample in three axes during the exposure. Practically, structures have been written using protons with an energy of 1.8 MeV in a provisional experimental setup with beam diameters of 10 and 50 mu m, respectively. After irradiation, the parts exposed were dissolved in a liquid developer without affecting the nonirradiated parts. The shape and the rms roughness of the resulting structures were estimated by optical microscopy and atomic force microscopy (AFM). (C) 1998 Elsevier Science B.V.