AVS 60th International Symposium and Exhibition
    Plasma Science and Technology Tuesday Sessions
       Session PS-TuP

Paper PS-TuP33
Development of ICP Etching Processes for Gallium Nitride HEMT

Tuesday, October 29, 2013, 6:00 pm, Room Hall B

Session: Plasma Science and Technology Poster Session
Presenter: T. Nishimiya, SAMCO Inc., Japan
Authors: S. Uehara, SAMCO Inc., Japan
T. Nishimiya, SAMCO Inc., Japan
Y. Kusuda, SAMCO Inc., Japan
M. Hiramoto, SAMCO Inc., Japan
S. Motoyama, SAMCO Inc., Japan
O. Tsuji, SAMCO Inc., Japan
Correspondent: Click to Email
Next-generation power devices fabricated from wide band-gap semiconductors, such as Gallium Nitride (GaN) or Silicon Carbide (SiC), have the advantages of less energy consumption and smaller device size compared to Silicon power devices, and therefore, are expected to see application in hybrid and electric vehicles, trains, wind or solar power generators, and smart grid technology. This paper reports our recent development of manufacturing processes for a GaN High-Electron-Mobility Transistor (HEMT).

A planar structure GaN-HEMT enables high-speed switching with a two-dimensional electron gas (2DEG), but it is a normally-on device while a normally-off device is preferable. To realize normally-off planar GaN-HEMTs, precise thickness control of the AlGaN layer at the gate is necessary. However, reproducible, stable thickness control of the AlGaN layer in the etching process is challenging when manufacturing normally-off GaN HEMTs. For this reason, we developed a slow etching process with low damage and high reproducibility, combined with in-situ thickness measurement using an optical interferometric film thickness monitor.

Manufacturing GaN-HEMTs with a triple channel (Camel) structure requires an etching process with high GaN to AlGaN selectivity on the p-GaN substrate. We developed an etching process with GaN to AlGaN selectivity of 60:1. We also applied interferometric film thickness monitoring for high etch process reproducibility. Another challenge in the Camel GaN-HEMT structure is to prevent current collapse, which prevents drain current, caused by electron traps on the interface of the AlGaN and insulation layers. We managed this issue by lowering the interface states of the AlGaN.