Fabrication and Performance of InAlN/GaN-on-Si MOSHEMTs with LaAlO₃ Gate Dielectric Using Gate-First CMOS Compatible Process at Low Thermal Budget

Abstract

A gate-first CMOS compatible process at low thermal budget to fabricate InAlN/GaN-on-Si MOSHEMTs is reported. This is made possible by a good quality LaAlO3 gate dielectric (k ~ 21.8) and Hf/Al/Ta ohmic contacts that require low annealing temperature. The reverse leakage current of the W/LaAlO3 gate stack remains low (< 3´10-7 mA/mm at -10 V) upon ohmic contact annealing at 600 oC. The fabricated LaAlO3 gate dielectric MOSHEMTs demonstrate a reasonable DC performance (Idsat ~ 510 mA/mm, Gmax ~ 44 mS/mm) for a 1 μm gate length device.

Influences of different oxidants on characteristics of La${}_{2}$O${}_{3}$/Al${}_{2}$O${}_{3}$ nanolaminates deposited by atomic layer deposition

“…When H 2 O was used as the oxidant, the container was set at room temperature, corresponding to a vapor pressure of 7 hPa. The ozone generator used the ultra pure O 2 (99.999%) to obtain O 3 , the concentration was 200 g/Nm 3 The composition variations of XPS spectra for the La 2 O 3 /Al 2 O 3 nanolaminates before and after annealing can be explained by the percentage composition of atomic atom variation, which is shown in Table 1. For the H 2 O-based ALD process, the percentage composition of atomic atom ratio of La:Al:O is close to 1:1:3 and it changes to almost 1:2:5 after annealing.…”

“…Recently, rare earth oxides such as La-based binary or ternary compounds, have received a lot of attention for their potential use as second generation high dielectric constant materials instead of the currently used Hf-based dielectrics in complementary metal-oxide-semiconductor technology. [1][2][3][4][5] Among these rare earth oxides, lanthanum oxide is considered to be a potential candidate due to its superior properties such as a high dielectric constant (> 26), large band gap (> 5.8 eV) and high electrical breakdown field strength. [6,7] It is also considered to overcome the low crystallization temperature problems with other high-κ dielectrics such as HfO 2 , as it has a high crystallization temperature of >900 • C. [8,9] To meet the requirements for the dielectric quality improving and thickness scaling, atomic layer deposition (ALD) has become the preferred industrial deposition technique for high-κ oxides because of its low deposition temperature, excellent thickness and composition control, and conformal growth.…”