Comparisons of SiN Passivation Film Deposited by PE-CVD and T-CVD Method for AlGaN/GaN HEMTs on SiC Substrate

Hideyuki OKITA
Toshiharu MARUI
Shinichi HOSHI
Masanori ITOH
Fumihiko TODA
Yoshiaki MORINO
Isao TAMAI
Yoshiaki SANO
Shohei SEKI

Publication
IEICE TRANSACTIONS on Electronics   Vol.E92-C    No.5    pp.686-690
Publication Date: 2009/05/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E92.C.686
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
Category: 
Keyword: 
AlGaN/GaN HEMTs,  current collapse,  SiN,  passivation film,  thermal CVD,  

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Summary: 
Current collapse phenomenon is a well known obstacle in the AlGaN/GaN HEMTs. In order to improve the surface stability of HEMTs, we have investigated the SiN passivation film deposited by T-CVD, and we found that it improves both gate leakage current and current collapse phenomenon [1]. Moreover, we compared the T-CVD and PE-CVD passivation films, on high electric field DC and RF characteristics. We found that T-CVD SiN passivation film improves BVds-off by 30% because of the reduction of gate leakage current. It also improved ηd in the output power characteristics by load-pull measurement, which indicates the decrease of the current collapse phenomenon. Also we fabricated a multi-fingered 50 W-class AlGaN/GaN HEMT with T-CVD SiN passivation film and achieved 61.2% of high drain efficiency at frequency of 2.14 GHz, which was 3.6 points higher than that with PE-CVD SiN passivation film.