Title: | Application of Pd/Ge/Cu alloyed ohmic contact system to n-type GaAs for fully Cu-metallized InGaP/GaAs HBTs |
Authors: | Chen, Ke-Shian Chang, Edward Yi Lin, Chia-Ching Lee, Cheng-Shih 材料科學與工程學系 Department of Materials Science and Engineering |
Keywords: | Copper;GaAs;HBT;Metallization;Ohmic contact |
Issue Date: | 1-Feb-2009 |
Abstract: | Use of the Pd/Ge/Cu multilayers as the emitter and collector ohmic metal for the fully Cu-metallized InGaP/GaAs heterojunction bipolar transistors is studied. The Pd/Ge/Cu ohmic contact exhibited a very low contact resistance of 5.73 x 10(-7) Omega cm(2) at a low annealing temperature (250 degrees C) and the microstructure evolution of Pd/Ge/Cu ohmic contact was investigated using transmission electron microscopy and energy dispersive spectrometer. We also did some comparisons between the Pd/Ge/Cu, Pd/Ge/Ti/Pt/Cu, and the traditional Au/Ge/Ni/Au ohmic contact structures to n-type GaAs. The common emitter I-V curves and Gummel plot of these Cu-metallized HBTs using Pd/Ge/Cu ohmic contact and Cu interconnects showed similar electrical characteristics as those HBTs with conventional Au-metallization. The cutoff frequency (f(T)) of 3 x 20-mu m-emitter-area devices was about 38 GHz. During both the current-accelerated stress test (110 kA/cm(2) stress for 24 h) and the thermal stability test (annealing at 250 degrees C for 24 h), the fully Cu-metallized HBT with Pd/Ge/Cu ohmic contact and Cu interconnects showed almost no obvious degradation in electrical characteristics. The results show that the Pd/Ge/Cu ohmic contact in combination with the Cu interconnects can be used on HBT devices to achieve the Au-free fully Cu-metallized lnGaP/GaAs HBTs, and the devices exhibit good device performance. (C) 2008 Elsevier Ltd. All rights reserved. |
URI: | http://dx.doi.org/10.1016/j.sse.2008.10.017 http://hdl.handle.net/11536/7666 |
ISSN: | 0038-1101 |
DOI: | 10.1016/j.sse.2008.10.017 |
Journal: | SOLID-STATE ELECTRONICS |
Volume: | 53 |
Issue: | 2 |
Begin Page: | 154 |
End Page: | 159 |
Appears in Collections: | Articles |
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