Air Gaps Fabrication for Sub-100 nm GaN HEMTs by Novel SF6 Plasma Etching
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.
Fields of Study & Subjects
GaN-based semiconductor devices and materials
Semiconductor Quantum Structures and Devices
Advancements in Semiconductor Devices and Circuit Design
Publication details
- Journal / source
- Microelectronics
- Publisher
- MDPI AG
- Volume
- 2
- Issue
- 1
- Pages
- 1–1
- Publication date
- 13 January 2026
- Language
- EN