A Study on Hot Carrier Effects on N-MOSFET's Under High Substrate Impurity Concentration

Mizuki Ono, Masanobu Saito, Takashi Yoshitomi, Claudio Fiegna, Tatsuya Ohguro, Hisayo Sasaki Momose, Hiroshi Iwai

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


A systematic investigation of the influences of high substrate doping on the hot carrier characteristics of small geometry n-MOSFET's down to 0.1 μm has been carried out. Results indicate that the dependence of substrate current and impact ionization rate on substrate impurity concentration is reversed in long channel and short channel devices. In the long channel case, both increase with rising substrate impurity concentration, while they decrease in the case of short channel devices. An explanation for this phenomenon based on the lucky electron model has been developed. The dependence of other characteristics on impurity concentration has also been studied. The dependence of off-leakage current has been found to fall as the gate oxide is reduced in thickness. Regarding the dependence of hot carrier degradations, the degradation of drain currents becomes smaller as the substrate impurity concentration increases in the case of short channel devices. Further, in the extremely high impurity doping region, a new hot carrier degradation mode was found, in which the maximum transconductance values of n-MOSFET's increase after hot carrier stress. This new degradation mode can be explained in terms of effective channel length shortening caused by electron trapping.

Original languageEnglish
Pages (from-to)1510-1521
Number of pages12
JournalIEEE Transactions on Electron Devices
Issue number8
StatePublished - Aug 1995

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