skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Ion and Neutral Species in C(2)F(6) and CHF(3) Dielectric Etch Discharges

Abstract

Relative concentrations of reactive ions, neutral radicals, resist and substrate etch products have been measured in dielectric etch chemistries using an uncollided beam mass spectrometer / ion extractor from Hiden Analytical. Analysis techniques employed include both electron impact ionization and dissociative ionization of neutral gas, and potential bias extraction of positive ions from the reactor discharge volume. Measurements were made in C{sub 2}F{sub 6} and CHF{sub 3} discharges in an inductively coupled plasma (ICP-GEC) research reactor operating with power densities, pressures, gas compositions and wafer materials typical of those found in etch processing tools. Wafer substrates investigated included blanket silicon wafers and silicon wafers with varying amounts of photo-resist coverage of the surface (20%, 80% and 100%). In C{sub 2}F{sub 6} discharges CF{sub 3}{sup +} was consistently the dominant fluorocarbon ion present, in agreement with published cross sections for dissociative ionization [ 1,2.3,4.5,6]. Smaller concentrations of CF+, CF{sub 2}{sup -}, and C{sub 2}F{sub 5}{sup +}, were also observed, though the dissociative ionization production of C{sub 2}F{sub 5}{sup +} was a factor of five smaller than would be expected from published cross section values. The presence of photo-resist, even in small amounts, was found to produce marked changes in the dischargemore » composition. For example in C{sub 2}F{sub 6} discharges, concentrations of SiF{sub x} etch products relative to concentrations of C{sub x}F{sub y} species were notably diminished and larger concentrations of water vapor were observed when resist was present. In CHF{sub 3} discharges, CF{sub 3}{sup +} and CHF{sub 2}{sup +} were found to be the main species present, along with smaller concentrations of CF{sub 2}{sup +}, CF{sup +}, CHF{sup +}, CH{sup +} and F{sup -}.« less

Authors:
; ;
Publication Date:
Research Org.:
Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
3221
Report Number(s):
SAND99-0172J
ON: DE00003221
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Journal Article
Journal Name:
Journal Vacuum Science and Technology
Additional Journal Information:
Journal Name: Journal Vacuum Science and Technology
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 36 MATERIALS SCIENCE; Ions; Radicals; Coatings; Substrates; Concentration Ratio; Etching

Citation Formats

Hebner, G, Jayaraman, R P, and McGrath, R T. Ion and Neutral Species in C(2)F(6) and CHF(3) Dielectric Etch Discharges. United States: N. p., 1999. Web.
Hebner, G, Jayaraman, R P, & McGrath, R T. Ion and Neutral Species in C(2)F(6) and CHF(3) Dielectric Etch Discharges. United States.
Hebner, G, Jayaraman, R P, and McGrath, R T. 1999. "Ion and Neutral Species in C(2)F(6) and CHF(3) Dielectric Etch Discharges". United States. https://www.osti.gov/servlets/purl/3221.
@article{osti_3221,
title = {Ion and Neutral Species in C(2)F(6) and CHF(3) Dielectric Etch Discharges},
author = {Hebner, G and Jayaraman, R P and McGrath, R T},
abstractNote = {Relative concentrations of reactive ions, neutral radicals, resist and substrate etch products have been measured in dielectric etch chemistries using an uncollided beam mass spectrometer / ion extractor from Hiden Analytical. Analysis techniques employed include both electron impact ionization and dissociative ionization of neutral gas, and potential bias extraction of positive ions from the reactor discharge volume. Measurements were made in C{sub 2}F{sub 6} and CHF{sub 3} discharges in an inductively coupled plasma (ICP-GEC) research reactor operating with power densities, pressures, gas compositions and wafer materials typical of those found in etch processing tools. Wafer substrates investigated included blanket silicon wafers and silicon wafers with varying amounts of photo-resist coverage of the surface (20%, 80% and 100%). In C{sub 2}F{sub 6} discharges CF{sub 3}{sup +} was consistently the dominant fluorocarbon ion present, in agreement with published cross sections for dissociative ionization [ 1,2.3,4.5,6]. Smaller concentrations of CF+, CF{sub 2}{sup -}, and C{sub 2}F{sub 5}{sup +}, were also observed, though the dissociative ionization production of C{sub 2}F{sub 5}{sup +} was a factor of five smaller than would be expected from published cross section values. The presence of photo-resist, even in small amounts, was found to produce marked changes in the discharge composition. For example in C{sub 2}F{sub 6} discharges, concentrations of SiF{sub x} etch products relative to concentrations of C{sub x}F{sub y} species were notably diminished and larger concentrations of water vapor were observed when resist was present. In CHF{sub 3} discharges, CF{sub 3}{sup +} and CHF{sub 2}{sup +} were found to be the main species present, along with smaller concentrations of CF{sub 2}{sup +}, CF{sup +}, CHF{sup +}, CH{sup +} and F{sup -}.},
doi = {},
url = {https://www.osti.gov/biblio/3221}, journal = {Journal Vacuum Science and Technology},
number = ,
volume = ,
place = {United States},
year = {Tue Jan 26 00:00:00 EST 1999},
month = {Tue Jan 26 00:00:00 EST 1999}
}