Accurate determination of ultrathin gate oxide thickness and effective polysilicon doping of CMOS devices

Ashawant Gupta*, Peng Fang, Miryeong Song, Ming Ren Lin, Don Wollesen, Kai Chen, Chen-Ming Hu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

33 Scopus citations

Abstract

We present an efficient and accurate method to characterize the physical thickness of ultrathin gate oxides (down to 25 Å) and the effective polysilicon doping of advanced CMOS devices. The method is based on the model for Fowler-Nordheim (F-N) tunneling current across the gate oxide with correction in gate voltage to account for the polysilicon-gate depletion. By fitting the model to measured data, both the gate oxide thickness and the effective poly doping are unambiguously determined. Unlike the traditional capacitance-voltage (C-V) technique that overestimates thin-oxide thickness and requires large area capacitor, this approach results in true physical thickness and the measurement can be performed on a standard sub-half micron transistor. The method is suitable for oxide thickness monitoring in manufacturing environments.

Original languageEnglish
Pages (from-to)580-582
Number of pages3
JournalIEEE Electron Device Letters
Volume18
Issue number12
DOIs
StatePublished - 1 Dec 1997

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