AlGaN/GaN MIS-HEMTs With High Quality ALD-Al2O3 Gate Dielectric Using Water and Remote Oxygen Plasma As Oxidants

Huan-Chung Wang,Edward Yi Chang,Ting-En Hsieh,Chang Fu Dee,Yueh-Chin Lin,Quang Ho Luc,Chia-Hsun Wu,Shih-Chien Liu,Burhanuddin Yeop Majlis

doi:10.1109/jeds.2017.2779172

Abstract

We demonstrate the electrical performances of AlGaN/GaN metal–insulator–semiconductorhigh electron mobility transistors (MIS-HEMTs) with high quality Al2O3 gate dielectric deposited by plasma enhanced atomic layer deposition using both H2O and remote O2 plasma as oxygen sources. Excellent gate-dielectric/GaN interface and Al2O3 film quality were obtained, resulting in a very small threshold voltage hysteresis and a low interface trap density. The MIS-HEMT device exhibited high on/off current ratio of $\sim 10^{10}$ , steep subthreshold slope, small gate leakage current, low dynamic on-resistance degradation, and effectively current collapse suppression. These results indicate that incorporating remote O2 plasma in the ALD-Al2O3 deposition process is an effective and simple way to provide high quality gate dielectric for the GaN MIS-HEMTs production

Highlights

AlGaN/GaN high electron mobility transistors (HEMTs) show potential to be economically viable alternatives to silicon- or SiC-based power devices because of its inherent material properties
Conventional Schottky gate HEMTs suffer from high gate-source leakage current, which limits the efficiency of the GaN-based power device
Several groups have reported that using ozone (O3) as oxygen precursor to suppress these defective bonds in the ALDAl2O3 film, high performance GaN MIS-HEMTs can be achieved [7], [8]

Summary

INTRODUCTION

AlGaN/GaN high electron mobility transistors (HEMTs) show potential to be economically viable alternatives to silicon- or SiC-based power devices because of its inherent material properties. Conventional Schottky gate HEMTs suffer from high gate-source leakage current, which limits the efficiency of the GaN-based power device To overcome this problem, a typical method is using an insulator layer inserted between the gate metal and AlGaN, forming a metal–insulator–semiconductor (MIS)- HEMTs structure [1]–[4]. There are significant amount of defective states such as Al–Al and Al–O–H bonds observed in the H2O-sourced ALD-Al2O3 film. Several groups have reported that using ozone (O3) as oxygen precursor to suppress these defective bonds in the ALDAl2O3 film, high performance GaN MIS-HEMTs can be achieved [7], [8]. We fabricated GaN MIS-HEMTs with Al2O3/AlN stack gate dielectric, in which the quality of the Al2O3 film was improved by utilizing H2O and remote O2 plasma as oxidants. The influence of incorporating remote O2 plasma in the ALD-Al2O3 process on the device performance was characterized by capacitance-voltage (CV), DC, and pulsed I-V measurements

DEVICE FABRICATION

RESULT

CONCLUSION