Air Gaps Fabrication for Sub-100 nm GaN HEMTs by Novel SF6 Plasma Etching
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.
Authors
- Mariyam Salmi
- Hassan Maher (ORCID: https://orcid.org/0000-0002-3827-2517)
- Erwine Pargon
- Simon St-Jacques
- Oleh Fesiienko
- Ali Soltani
Institutions
- Institut polytechnique de Grenoble (FR)
- Centre National de la Recherche Scientifique (FR)
- Université de Sherbrooke (CA)
- Commissariat à l'Énergie Atomique et aux Énergies Alternatives (FR)
- CEA Grenoble (FR)
- Laboratoire d'Électronique des Technologies de l'Information (FR)
- Université Grenoble Alpes (FR)
Publication Details
- Journal
- Microelectronics
- Published
- 2026-01-13
- DOI
- https://doi.org/10.3390/microelectronics2010001
- Citations
- 1
- Primary Topic
- GaN-based semiconductor devices and materials
- Type
- article
- Field-Weighted Citation Impact
- 26.95
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