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Scanning tunneling microscopy study of nitrogen incorporated HfO{sub 2}

Journal Article · · Journal of Applied Physics
DOI:https://doi.org/10.1063/1.2982406· OSTI ID:21182644
; ; ;  [1]; ;  [2];  [3]
  1. Nanyang Technological University, School of Electrical and Electronic Engineering, Nanyang Avenue, Singapore 639798 (Singapore)
  2. Institute of Materials Research and Engineering, A-STAR - Agency for Science, Technology and Research, 3 Research Link, Singapore 11760 (Singapore)
  3. Institute of Microelectronics, A-STAR - Agency for Science, Technology and Research, 11 Science Park Road, Singapore Science Park II, Singapore 117685 (Singapore)
The impact of nitrogen incorporation on the physical and electrical characteristics of the HfO{sub 2} is examined. X-ray photoelectron spectroscopy shows that nitrogen can be incorporated into the HfO{sub 2} via a two-step thermal anneal--first in ultrahigh vacuum (UHV) and subsequently in N{sub 2}. Following the N{sub 2} anneal, scanning tunneling microscopy in UHV reveals a marked reduction in the low-voltage leakage current under gate injection biasing. From band theory and existing first-principles simulation results, one may consistently attribute this improvement to the passivation of oxygen vacancies in the HfO{sub 2} by nitrogen. Improvement in the breakdown strength of the HfO{sub 2} subjected to ramp-voltage stress (substrate injection) is also observed after the N{sub 2} anneal. The local current-voltage curves acquired concurrently during the ramp-voltage stress exhibit 'space-charge limited conduction', which implies that the observed improvement in breakdown strength may be related to a limitation of the current flow through the gate stack in the high stress voltage regime.
OSTI ID:
21182644
Journal Information:
Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 6 Vol. 104; ISSN JAPIAU; ISSN 0021-8979
Country of Publication:
United States
Language:
English

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