T. Jang

Development of chip shrink technology for lateral-type GaN based HFETs using SiO2/polyimide dual IMD layers

This study examined chip shrink technology for lateral-type AlGaN/GaN HFETs on 150 mm Si substrates fabricated with a bonding pad above the active area (BPAA) structure. The SiO2/polyimide layers were used as inter metal dielectric (IMD) layers, which yielded a very low leakage current of 0.58 nA/mm2 even at 1 kV and a good adhesion property after O2 plasma treatment. The fabricated AlGaN/GaN HFETs with the BPAA structure exhibited good device characteristics, such as a low leakage current of 7.1 nA at 1 kV and a drain current of 3.6 A at 2 V, which has the same value compared to that of the AlGaN/GaN HFETs without the BPAA structure, even though the BPAA structure reduced the size of chip by 40%. This suggests that the BPAA structure is a promising method for reducing the size and cost of the lateral-type AlGaN/GaN HFETs.

Gate Metal Dependent Reverse Leakage Mechanisms in AlGaN/GaN Schottky Diode

The dependence of the gate leakage mechanism in the AlGaN/GaN Schottky diode on the metal–semiconductor (MS) interface state has been investigated. Schottky gates with Au, Pt, Pd, and Ni showed the remarkably different gate leakage mechanisms in the reverse direction. Through the analysis of the temperature dependent reverse leakage currents, it is shown that the discrete energy levels of MS interface states are the key factor in determining whether the leakage mechanism at the high temperature over 300 K is caused by the electron tunneling or by the Frenkel–Poole emission from the MS interface state to the conductive dislocation state.

Investigations on the Dynamic On-Resistance of High Voltage AlGaN/GaN HFETs

AlGaN/GaN HFETs with sufficiently larger thicknesses of undoped GaN channel improved dynamic on-state resistance. The role of undoped GaN channel in AlGaN/GaN HFETs was understood and better performed device was fabricated.