Pulsed Plasma Etching of Multilayer Films for Recess Shape Control

The patent applies periodic action by intermittently or periodically supplying pulses of source radio frequency power and pulses of electric bias during the etching process. This periodic supply allows precise control over plasma generation and ion attraction, enabling accurate control of recess depth and width while preventing unwanted expansion. The periodic pulsing creates controlled etching cycles that maintain dimensional accuracy.

The patent employs parameter changes by using different process gases for etching different film types (silicon oxide versus silicon nitride). This change in process gas parameters enables selective and precise etching of each layer, improving control over the final recess dimensions and preventing expansion while achieving the desired depth profile.

The periodic supply of source radio frequency power and electric bias creates controlled etching cycles that advance the recess depth while maintaining width control. The intermittent pulsing allows precise progression into deeper regions without lateral expansion, as each pulse cycle carefully manages plasma density and ion directionality to etch vertically rather than laterally.

The patent applies local quality by using different process gases tailored for etching specific film types at different locations in the multilayer structure. This localized approach ensures that each region is etched with optimal gas chemistry, maintaining precise width control while achieving the required depth, preventing uniform expansion across the recess width.