We present a novel 3D fabrication method utilizing a deep X-ray mask in which an electro-thermal micro xy-stage is integrated. The absorber of the X-ray mask is formed on the shuttle mass of the micro xy-stage and it is oscillated in x- and y-directions during exposures to modify the in-depth dose profile in the resist, usually PMMA. Curved or slanted microstructures are revealed by the modulated dose distribution and the development kinetics of the resist. The nuicro xy-stage is fabricated using a silicon-on-insulator (SOI) wafer, resulting in overhanging, 20 mum thick single-crystal silicon microstructures. It has 20 mum wide, 1 mm long bent-beam electro-thermal actuators along each axis and 10 mum wide, 1 mm long suspension beams supporting a 1.42 mm diameter shuttle mass. Displacements of the shuttle mass in x- and y-directions are both around 20 mum at 742 mW dc input power. Two-dimensional (2D) sinusoidal and tapered microstructures are fabricated through shuttle mass oscillation in two axes during exposures. (C) 2003 Elsevier B.V. All rights reserved.