Study of the manufacturing feasibility of 1.5-nm direct-tunneling gate oxide MOSFET's: Uniformity, reliability, and dopant penetration of the gate oxide

Hisayo Sasaki Momose*, Shin Ichi Nakamura, Tatsuya Ohguro, Takashi Yoshitomi, Eiji Morifuji, Toyota Morimoto, Yasuhiro Katsumata, Hiroshi Iwai

*Corresponding author for this work

Research output: Contribution to journalArticle

87 Scopus citations

Abstract

Although direct tunneling gate oxide MOSFET's are expected to be useful in high-performance applications of future large-scale integrated circuits (LSI's), there are many concerns related to their manufacture. The uniformity, reliability, and dopant penetration of 1.5-nm direct-tunneling gate oxide MOSFET's were investigated for the first time. The variation of oxide thickness in an entire 150-mm wafer was evaluated by TEM and electrical measurements. Satisfactory values of standard deviations in the TEM measurements and threshold voltage measurements for MOSFET's with a gate area of 5 /urn x 0.75 urn, were obtained. These values improved significantly in the case of MOS capacitors with larger gate areas. The oxide breakdown field and the reliability with respect to charge injection were evaluated for the 1.5-nm gate oxides and found to be better than those of thicker gate oxides. Dopant penetration was not observed in n+ polysilicon gates subjected to RTA at 1050 °C for 20 s and furnace annealing at 850 °C for 30 min. Although much more data will be required to judge the manufacturing feasibility, these results suggest that 1.5-nm directtunneling oxide MOSFET's are likely to have many practical applications.

Original languageEnglish
Pages (from-to)691-700
Number of pages10
JournalIEEE Transactions on Electron Devices
Volume45
Issue number3
DOIs
StatePublished - 1998

Keywords

  • Direct-tunneling
  • Gate oxide
  • Leakage current
  • MOSFET
  • Reliability

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