Atmospheric HF vapor based silicon etching with Pt catalyst for high fidelity through silicon via (TSV) fabrication

We report a dry mode metal assisted chemical etching (d-MaCE) process for directional microscale silicon etching for the first time. The etching is performed under a condition of diluted HF vapor, Pt-catalyst, and standard atmosphere for cost effective high fidelity through silicon via (TSV) fabrication. Implementation of a prototype etching system, various etching experiments under different HF concentrations and substrate temperature, and their results are reported. The d-MaCE process offers an opportunity for the formation of scallop- free smooth sidewalled TSVs with a surface roughness of 50 nm or less. This smoothness is crucial for modern high speed high bandwidth low loss TSV interconnects. TSV holes with their diameters of 50 - 150 μm are fabricated in roughly 1 atmosphere. The obtained maximum etching rate is 18μm/hr with an HF concentration of 28.9 mol/L and a substrate temperature of 60°C.