Oxygen Plasma Damage Study on InGap/GaAs HBTs

Sheila O'Neil, Shiban Tiku, Datherine Lou, Peter Zampardi  
Skyworks Solutions, Inc. 2427 Hillcrest Drive, Newbury Park, CA  91320 
Email: sheila.oneil@skyworksinc.com

This paper presents the results of investigations into the effect of oxygen plasma damage to InGaP/GaAs HBTs.  The study examined the PCM data and the results of reliability tests performed on devices that had been exposed to various plasma intensities at two different processing steps.  Our results show that direct exposure of the HBT to plasma after formation of the base pedestal can result in poor reliability.  The degradation in reliability had an unusual correlation to plasma intensity.  In addition, a thin SiN layer can effectively protect the HBT from plasma damage. 

Keywords: plasma damage, ICP, reliability, PCM

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