Dry etching of GaN and related materials: comparison of techniques

摘要

The etch rates and feature anisotropy for GaN, AlN, and InN etchednin Cl2-Ar plasmas with four different techniques werenexamined. Conventional reactive ion etching produces the slowest etchnrates, even when high dc self-biases (>-900 V) are employed, and thisnleads to mask erosion and sloped feature sidewalls during ridgenwaveguide fabrication. Two high-ion-density techniques, inductivelyncoupled plasma and electron cyclotron resonance, provide the highestnetch rates and most anisotropic features through their combination ofnhigh-ion flux and moderate-ion energy. Etch selectivities of GaN to AlNnand InN are typically ⩽4 in these tools. Reactive ion beam etchingnutilizing a high density (ICP) source is also an attractive option fornpattern transfer in the nitrides, although its etch rates are slowernthan for ICP or ECR due to its lower operating pressure