Deep X-ray mask with integrated electro-thermal micro xy-stage for 3D fabrication

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 micro xy-stage is fabricated using a silicon-on-insulator (SOI) wafer, resulting in overhanging, 20 μm thick single-crystal silicon microstructures. It has 20 μm wide, 1 mm long bent-beam electro-thermal actuators along each axis and 10 μm 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 μm at 742 mW dc input power. Two-dimensional (2D) sinusoidal and tapered microstructures are fabricated through shuttle mass oscillation in two axes during exposures.

[1]  D. Maas,et al.  Fabrication of microcomponents using adhesive bonding techniques , 1996, Proceedings of Ninth International Workshop on Micro Electromechanical Systems.

[2]  O. Tabata,et al.  Fabrication of 3-dimensional microstructures using moving mask deep X-ray lithography (M/sup 2/DXL) , 2001, Technical Digest. MEMS 2001. 14th IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.01CH37090).

[3]  Dose distribution of synchrotron x-ray penetrating materials of low atomic numbers , 1997 .

[4]  H. Guckel,et al.  High-aspect-ratio micromachining via deep X-ray lithography , 1998, Proc. IEEE.

[5]  O. Tabata,et al.  3D fabrication by moving mask deep X-ray lithography (M/sup 2/DXL) with multiple stages , 2002, Technical Digest. MEMS 2002 IEEE International Conference. Fifteenth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.02CH37266).

[6]  Susumu Sugiyama,et al.  Direct writing for three-dimensional microfabrication using synchrotron radiation etching , 2000 .

[7]  Alan Feinerman,et al.  X-ray lathe: An X-ray lithographic exposure tool for nonplanar objects , 1996 .

[8]  Y. Gianchandani,et al.  Bent-beam electrothermal actuators-Part I: Single beam and cascaded devices , 2001 .

[9]  Susumu Sugiyama,et al.  Novel Shaped Microstructures Processed by Deep X-Ray Lithography , 2001 .

[10]  W. Ehrfeld,et al.  Recent developments in deep x-ray lithography , 1998 .

[11]  Liwei Lin,et al.  Batch transfer of LIGA microstructures by selective electroplating and bonding , 2001 .

[12]  Deep X-ray mask with integrated actuator for 3D microfabrication , 2003 .

[13]  T. Christenson,et al.  A batch wafer scale LIGA assembly and packaging technique via diffusion bonding , 1999, Technical Digest. IEEE International MEMS 99 Conference. Twelfth IEEE International Conference on Micro Electro Mechanical Systems (Cat. No.99CH36291).

[14]  Denice D. Denton,et al.  X-ray fabrication of nonorthogonal structures using “surface” masks , 1997 .