Deep reactive ion etching (DRIE) enables high-precision silicon etching for MEMS device fabrication. The process forms deep trenches and cavities while maintaining steep sidewalls and tight dimensional control. Engineers choose DRIE over conventional plasma etching when device geometry demands deep, vertical features: the combination of anisotropy, dimensional accuracy, and run-to-run repeatability makes it the default choice for high-aspect-ratio silicon structures. DRIE builds the deep geometry. Vertical 90±1° sidewalls at aspect ratios to 15:1, from 5µm-deep features to through-wafer etches, with 3µm minimum features. The patterned mask defines each feature; the directional plasma removes silicon only where the mask is open. Standard DRIE technical specifications: - Aspect Ratio: Standard processing up to 15:1 - Etch Depth: 5µm to through-wafer - Minimum Feature (CD): 3µm - Sidewall Profile: Vertical profiles maintained at 90 ±1 degrees - Uniformity: Depth uniformity within ±5% on deep etches, with controlled feature dimensions from center to edge of 200mm silicon wafers DRIE silicon etching enables the three-dimensional microstructures that define MEMS device performance, including: - Pressure sensor cavities - Microfluidic channels - Suspended mechanical structures - MEMS actuators and resonators - Optical MEMS components DRIE or Wet Etch? DRIE produces vertical, high-aspect-ratio features, while anisotropic silicon wet etching with KOH or TMAH delivers crystal-plane geometry and batch-process economy. Plasma etch can also be combined with wet etch techniques for optimal results during MEMS fabrication. Our DRIE vs. silicon wet etch guide walks through the trade-offs. And when a metal resists etching altogether, our metal lift-off process patterns it additively instead.
