High-resolution projection microstereolithography (PµSL) has been successfully developed at the University of California Los Angeles. Incorporating a digital micromirror device made by Texas Instruments (Dallas, TX) as a dynamic spatial light modulator, the technology provides parallel fabrication of highly complex three-dimensional (3-D) microstructures for microelectromechanical systems (MEMS). In the technique, uniform ultraviolet (UV) light is modulated by switching individual micromirrors; then, through a 1:5 reduction lens, the reflected pattern is projected onto a UV-curable monomer resin surface. The illuminated area is solidified all at once during exposure, while the dark regions remain liquid. Complex 3-D microstructures are fabricated by stacking polymerized layers with confined thickness of a few microns. The fabrication of complex 3-D structures such as matrices and microspring arrays with feature sizes down to 5 µm has been achieved.
Using a digital micromirror device as the dynamic mask eliminates the cost of fabricating a mask for each layer. In addition, the PµSL process reduces fabrication time because each layer is fabricated in one exposure, and the time for mask alignment is eliminated. This process promises cost-effective, massively parallel fabrication of arrays of MEMS devices that can be integrated with IC processes. Contact Cheng Sun at [email protected].