skip to main content


Title: Fluorocarbon assisted atomic layer etching of SiO 2 and Si using cyclic Ar/C 4F 8 and Ar/CHF 3 plasma

The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C 4F 8 ALE based on steady-state Ar plasma in conjunction with periodic, precise C 4F 8 injection and synchronized plasma-based low energy Ar + ion bombardment has been established for SiO 2. 1 In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF 3 as a precursor is examined and compared to C 4F 8. CHF 3 is shown to enable selective SiO 2/Si etching using a fluorocarbon (FC) film build up. Other critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and X-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. As a result, plasma parameters during ALE aremore » studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.« less
 [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [1]
  1. Univ. of Maryland, College Park, MD (United States)
  2. IBM T.J. Watson Research Center, Yorktown Heights, NY (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films
Additional Journal Information:
Journal Volume: 34; Journal Issue: 1; Journal ID: ISSN 0734-2101
American Vacuum Society
Research Org:
Univ. of Maryland, College Park, MD (United States)
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE; silicon; dielectric oxides; thin films; plasma etching; ellipsometry
OSTI Identifier: