HF Plasma Etching of High-Aspect-Ratio Features With Profile Control

The patent changes the chemical parameters of the etching process by introducing HF gas as a specific etchant component and controlling the plasma chemistry to achieve selective etching. This chemical parameter change enables precise profile control and reduces harmful lateral erosion effects during high aspect ratio feature etching

The patent applies different etching conditions to different regions of the substrate by controlling plasma distribution and gas flow patterns. This local quality approach ensures uniform profile control across the substrate while minimizing bowing and maintaining circular hole shapes throughout the etching process

The patent employs periodic or pulsed RF power application to the plasma process, allowing controlled etching cycles that maintain high etch rates while preventing excessive ion bombardment damage. This periodic action enables productivity improvement without sacrificing profile control by resetting plasma conditions between etching pulses

The patent introduces HF gas as an intermediary chemical species that mediates the etching process. This intermediary enables efficient material removal through chemical reactions rather than purely physical sputtering, achieving high etch rates with reduced ion energy requirements and consequently less lateral erosion

The patent enhances the removal of etch by-products from the etching environment through optimized gas flow patterns and pressure control. This extraction approach prevents by-product accumulation that would otherwise degrade mask CD control during high aspect ratio feature etching

The patent replaces purely physical removal mechanisms with chemically-assisted by-product removal. The HF-based plasma chemistry facilitates volatile by-product formation that can be efficiently evacuated, substituting mechanical clearing approaches with chemical transformation and removal