High-performance normally off AlGaN/GaN-on-Si HEMTs with partially recessed SiN _x MIS structure

Abstract

Recessed MIS gate structures with SiNx gate dielectric layer were investigated for use in normally off AlGaN/GaN‐on‐Si high electron mobility transistors (HEMTs). The channel mobility and threshold voltage (Vth) instability were strongly affected by the recessed configuration. Employing a 30 nm SiNx gate dielectric layer composed of 6 nm PEALD and 24 nm ICP‐CVD films on a 2 nm AlGaN recessed barrier layer resulted in excellent electrical and dynamic characteristics with reduced effective interface trap density. A maximum drain current density of 590 mA mm−1, an on‐resistance of 0.75 mΩ · cm2, and a breakdown voltage of >1100 V were achieved for the gate‐to‐drain distance of 10 μm. Owing to the remaining AlGaN barrier layer under the recessed gate region of the partially recessed device, the interaction between MIS interface traps and channel electrons was suppressed effectively, resulting in improved channel mobility and Vth stability.

In Situ Infrared Absorption Study of Plasma-Enhanced Atomic Layer Deposition of Silicon Nitride

“…Silicon nitride (Si 3 N 4 ) thin films are important for applications in microelectronics such as dielectric layers in complementary metal oxide semiconductor devices, − gate spacers, ,− and diffusion barriers. − In particular, deposition of conformal thin films at low temperatures (<300 °C) is necessary for nanopatterned, three-dimensional substrates developed to satisfy scaling requirements. , Atomic layer deposition (ALD) has emerged as one of the best methods to achieve Si 3 N 4 deposition with adequate thickness control, conformality for highly patterned substrates, and chemical specificity. − A number of precursors have been developed for the growth of Si 3 N 4 for both thermal and plasma-enhanced processes. ,,− Among them, aminosilanes are particularly attractive because, unlike chlorosilanes, they generate noncorrosive halogenated products. ,, However, thermal processes with chlorosilanes or aminosilanes and either ammonia (NH 3 ) or hydrazine (N 2 H 4 ) require temperatures above 300 °C, which is not acceptable for several applications. ,,,,− Therefore, efforts have turned to plasma-enhanced processes that allow for low-temperature growth. ,,,,, For example, Knoops et al developed a plasma-enhanced atomic layer deposition (PEALD) process using bis­( t -butylamino)­silane (BTBAS) as a precursor and nitrogen plasma as a coreactant and demonstrated a large temperature window that allowed tunability of the film composition/properties by varying the growth conditions. , Although PEALD silicon nitride growth from aminosilane precursors shows great promise, the underlying reaction mechanisms and relationships between growth conditions and film composition must be understood to develop reliable industrial processes. , Some theoretical attempts have been made to underst...…”

High‐Performance E‐Mode AlGaN/GaN MIS‐HEMT with Dual Gate Insulator Employing SiON and HfON

“…The fabrication of the device was begun by depositing SiN x pre‐passivation layer using inductively coupled plasma chemical deposition (ICP‐CVD) . Ohmic contacts were formed with Ti/Al/Ni/Au metalli­zation and RTA annealing at 830 °C in N 2 am­bient.…”

Trap Characterization Techniques for GaN-Based HEMTs: A Critical Review

“…Consequently, the theoretical figure of merit limit of GaN HEMT is higher than that of Si and SiC-based power electronic devices. In recent years, GaN HEMTs have been intensively studied and widely used in RF amplifiers and power electronics systems [3][4][5].…”