Year: 2026
Type: article
Abstract: We demonstrate the fabrication of air gaps in a PECVD SiN interlayer through lateral recess by employing two consecutive plasma etch steps on an AlN/SiN/Al2O3 stack. This approach enables the preservation of sub-100 nm openings in Al2O3, offering a potential optimization for the GaN-HEMT gate stack in RF applications while retaining low gate foot dimensions. A low-power, SF6-based plasma etch is introduced, and time-dependent etch profiles reveal the formation of a skirt-like profile. The process exhibits excellent selectivity between SiN and Al2O3 etch rates. Furthermore, low-power SF6 plasma produces a small self-bias voltage, and surface fluorine contamination which can subsequently be eliminated by annealing.
Source: Microelectronics
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: diamond
Funders: Indian National Science Academy, Université de Sherbrooke, Université Grenoble Alpes, Agence Nationale de la Recherche, Centre National de la Recherche Scientifique, Institut National des Sciences Appliquées de Lyon, École Centrale de Lyon, Natural Sciences and Engineering Research Council of Canada, Fonds de recherche du Québec – Nature et technologies
OpenAlex ID: W7123944427