Anisotropic Etch

Anisotropic etch is a semiconductor etch process in which material is removed much more rapidly in one direction than another. The result is a feature with steep, vertical sidewalls instead of a rounded or undercut profile, which is essential for high-resolution pattern transfer.

The reason this matters is that modern chips need high aspect ratio structures. Deep trenches, contact holes, and vias require the etch to cut straight down while preserving sidewall integrity. Plasma-based reactive ion etching is a common way to achieve this because directional ion bombardment and sidewall passivation work together to favor vertical removal.

In practice, process conditions matter a lot. Low pressure, appropriate RF power, and carefully chosen chemistry improve anisotropy, while aspect ratio dependent etching can make very deep features harder to etch uniformly. Engineers often compensate with multi-step recipes or tuning of bias, gas flow, and passivation.

In short, anisotropic etch is a precision patterning step that creates straight-walled features needed for advanced semiconductor fabrication.