Shadow masks define device areas and form micro-structures with precision by masking or covering the target surface. Patterning a silicon wafer or substrate is usually processed with deposition using a photomask or direct-write lithography.
MLT shadow-masks are a rapid and cost effective alternative over photolithography when feature sizes are no smaller than 25um. Laser fabricated geometries achieve smaller dimensions, sharper edges, and tighter tolerances than chemical etching. Shadow masks can be fabricated from unconventional materials that eliminate possible chemical contamination or reactions. Laser fabricated limitations include:
— Maximum process tolerance is ± 10μm, application dependent.
— Minimum width of patterns is 20μm.
Mechanical supports or carrier frames can be fabricated to assist in handling and aligning shadow-masks to target device features.