TaN Versus TiN Metal Gate Input/Output pMOSFETs: A Low-Frequency Noise Perspective

It is shown that replacing a TiN effective work function metal by TaN results in a pronounced reduction of the low-frequency noise power spectral density (PSD) of thick-SiO
₂
input/output (I/O) DRAM peripheral pMOSFETs. The 1/
$f$
noise is originating from carrier number fluctuations, suggesting that the observed reduction results from a decrease of the oxide trap density in the SiO
₂
. On the other hand, I/O pMOSFETs with a TiN gate deposited by different methods or used as a sacrificial gate in a gate replacement integration scheme yield a similar high 1/
$f$
noise PSD and corresponding oxide trap density.