Impact of in situ NH₃ pre-treatment of LPCVD SiN passivation on GaN HEMT performance

Abstract

The impact on the performance of GaN HEMTs of in situ ammonia (NH3) pre-treatment prior to the deposition of silicon nitride (SiN) passivation with low-pressure chemical vapor deposition is investigated. Three different NH3 pre-treatment durations (0, 3, and 10 minutes) were compared in terms of interface properties and device performance. A reduction of oxygen at the interface between SiN and epi-structure is detected by Scanning Transmission Electron Microscopy-Electron Energy Loss Spectroscopy measurements in the sample subjected to 10 minutes of pre-treatment. The samples subjected to NH3 pre-treatment show a reduced surface-related current dispersion of 9 % (compared to 16% for the untreated sample), which is attributed to the reduction of oxygen at the SiN/epi interface. Furthermore, NH3 pre-treatment for 10 minutes significantly improves the current dispersion uniformity from 14.5 % to 1.9 %. The reduced trapping effects result in a high output power of 3.4 W/mm at 3 GHz (compared to 2.6 W/mm for the untreated sample). These results demonstrate that the in situ NH3 pre-treatment before low-pressure chemical vapor deposition of SiN passivation is critical and can effectively improves the large-signal microwave performance of GaN HEMTs.

Structural investigation of ultra-low resistance deeply recessed sidewall ohmic contacts for AlGaN/GaN HEMTs based on Ti/Al/Ti-metallization

“…The wafers were diced into 16 × 16 mm 2 samples and subsequently cleaned using RCA-1 and RCA-2 followed by diluted NH 4 OH to eliminate organic, metallic contaminants, and oxide. A passivation-first process was conducted by performing in-situ NH 3 pretreatment, followed by a 60 nm SiN deposition with low-pressure chemical vapor deposition (LPCVD) [23].…”

Impact of the Channel Thickness on Electron Confinement in MOCVD‐Grown High Breakdown Buffer‐Free AlGaN/GaN Heterostructures

“…For the HEMTs fabrication, a “passivation‐first” process scheme was applied with an in situ NH 3 pretreatment, to reduce surface native oxide and minimize surface‐related trapping effects, [ 20 ] followed by a deposition of 60 nm SiN passivation layer with low‐pressure chemical vapor deposition. The device isolation was achieved through mesa etching with a depth of ≈120 nm below 2DEG.…”

“…The pulse width was 1 μs with a duty cycle of 0.001%. The quiescent bias points (V GSQ , V DSQ ) were set at [(0, 0), (V poÀ 3, 0), (V poÀ 3,20), and (V poÀ 3, 25) V], denoted as [Q ref , Q 0 , Q 20 , and Q 25 ]. I ds-knee is defined at the knee where RF load-line is swinged of each I DS curve, marked with black dots in Figure 3.…”

Low-temperature characteristics and gate leakage mechanisms of LPCVD-SiNx/AlGaN/GaN MIS-HEMTs

“…SiNx film is widely used as a classic gate dielectric in AlGaN/GaN MIS-HEMTs, which can be deposited by various methods such as inductively coupled plasma chemical vapor deposition, plasma enhanced chemical vapor deposition, * Author to whom any correspondence should be addressed. and low-pressure chemical vapor deposition (LPCVD) [4][5][6]. Among of these methods, LPCVD can obtain higher quality of SiNx insulating dielectric and SiN/AlGaN interface due to depositing temperature exceeding 700 • C [7,8].…”