MEMS Evaporation Mask: 0.1 mm Electrode Case Study
What We Cut
These are evaporated metal masks for MEMS sensor electrodes. The interdigital pattern is 0.1 mm line and 0.1 mm space, with an annular ring tying the fingers together. We process these from thin nickel or copper foil before the wafer evaporation step. Any burr or curl on the mask transfers straight to the sensor die, so the edge quality has to be clean enough that the evaporated metal lands exactly where it should.
The Problem
The interdigital geometry is fragile. Standard laser cutting leaves resolidified debris on the 0.1 mm fingers. That debris welds back to the edge and blocks the evaporation path. Worse, the annular ring is a stress concentrator—cut it with too much heat and the fingers curl upward. We measured 15–20 μm curl on early trials. That kills the flatness required for wafer-level contact.
How We Fixed It
We split the job into two stages. Coarse features—the outer ring and bus lines—get laser micro-cut with a nanosecond IR source for speed. The 0.1 mm interdigital fingers get a second pass on a picosecond UV line. The UV pulse is short enough to sublimate the metal instead of melting it, so there is no resolidified debris. We also fixture the foil on a vacuum chuck with a ceramic backing plate. The backing absorbs the through-cut energy and keeps the fingers from curling. Final flatness is under 5 μm across the full mask.
Numbers That Matter
Semiconductor grade
MEMS sensor compatible
2-stage IR + UV workflow
Product Gallery
Evaporated Metal Mask (Interdigital Electrode)
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