Highly Reliable Submicron InP-Based HBTs with over 300-GHz ft

Norihide KASHIO
Kenji KURISHIMA
Yoshino K. FUKAI
Shoji YAMAHATA

Publication
IEICE TRANSACTIONS on Electronics   Vol.E91-C    No.7    pp.1084-1090
Publication Date: 2008/07/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.7.1084
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Heterostructure Microelectronics with TWHM 2007)
Category: GaAs- and InP-Based Devices
Keyword: 
InP HBTs,  passivation ledge,  reliability,  

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Summary: 
We have developed 0.5-µm-emitter InP-based HBTs with high reliability. The HBTs incorporate a passivation ledge structure and tungsten-based emitter metal. A fabricated HBT exhibits high collector current density and a current gain of 58 at a collector current density of 4 mA/µm2. The results of dc measurements indicate that the ledge layer sufficiently suppresses the recombination current at the emitter-base periphery. The HBT also exhibits an ft of 321 GHz and an fmax of 301 GHz at a collector current density of 4 mA/µm2. The ft does not degrade even though the emitter size is reduced to as small as 0.5 µm2 µm. The results of an accelerated life test show that the degradation of dc current gain is due to thermal degradation of the interfacial quality of semiconductors at the passivation ledge. The activation energy is expected to be around 1.5 eV, and the extrapolated mean time to failure is expected to be over 108 hours at a junction temperature of 125. These results indicate that this InP HBT technology is promising for making over-100-Gbit/s ICs with high reliability.