Characterization and removal of silicon surface residue resulting from CHF3/C2F6 reactive ion etching

Hyung-Ho Park, Kwang Ho Kwon, Jong Lam Lee, Kyung Soo Suh, Oh Joon Kwon, Kyoung Ik Cho, Sin Chong Park

Research output: Contribution to journalArticle

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Abstract

The surface properties of an underlying Si substrate after reactive ion etching of SiO2 in CHF3/C2F6 gas plasmas have been studied using x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry, Rutherford backscattering spectroscopy, and high resolution transmission electron microscopy (HRTEM). A 50-nm-thick silicon layer that contains carbon and fluorine and a 4-nm-thick uniform residue layer composed entirely of carbon, fluorine, oxygen, and hydrogen on the silicon surface have been observed. The residue film has nine different kinds of chemical bonds. At the surface, O - F bond is found on C - F polymer that contains C - CFx (x≤3), C - F1, C - F2, and C - F3 bonds. Between the C - F polymer layer and the silicon substrate, C - C/H, Si - C, Si - O, and Si - F bonds exist. Neither point defect clusters nor distinct planar defects are found in cross-sectional HRTEM images of the silicon substrate. The changes of peak shapes for C, Si, O, and F in the residual film have been analyzed through an in situ resistive anneal under ultrahigh vacuum condition. C - F1, C - F2, and C - F 3 bonds decompose and form C - CFx bonds above 200°C. Above 400°C, C - CFx bonds also decompose to C - C/H bonds. For removal of the silicon surface residue, reactive ion etched specimens have been exposed to O2, NF3, Cl2, and SF6 plasmas. By XPS analysis, NF3 treatment has been revealed to be the most effective. With 10 s exposure to NF3 plasma, the fluorocarbon residue film decomposes and the remaining fluorine is mostly bound to silicon. The fluorine completely disappears after wet cleaning.

Original languageEnglish
Pages (from-to)4596-4602
Number of pages7
JournalJournal of Applied Physics
Volume76
Issue number8
DOIs
Publication statusPublished - 1994 Dec 1

Fingerprint

etching
fluorine
silicon
ions
x ray spectroscopy
photoelectron spectroscopy
transmission electron microscopy
carbon
high resolution
fluorocarbons
polymers
chemical bonds
point defects
surface properties
cleaning
secondary ion mass spectrometry
ultrahigh vacuum
backscattering
defects
oxygen

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

Cite this

Park, Hyung-Ho ; Kwon, Kwang Ho ; Lee, Jong Lam ; Suh, Kyung Soo ; Kwon, Oh Joon ; Cho, Kyoung Ik ; Park, Sin Chong. / Characterization and removal of silicon surface residue resulting from CHF3/C2F6 reactive ion etching. In: Journal of Applied Physics. 1994 ; Vol. 76, No. 8. pp. 4596-4602.
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abstract = "The surface properties of an underlying Si substrate after reactive ion etching of SiO2 in CHF3/C2F6 gas plasmas have been studied using x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry, Rutherford backscattering spectroscopy, and high resolution transmission electron microscopy (HRTEM). A 50-nm-thick silicon layer that contains carbon and fluorine and a 4-nm-thick uniform residue layer composed entirely of carbon, fluorine, oxygen, and hydrogen on the silicon surface have been observed. The residue film has nine different kinds of chemical bonds. At the surface, O - F bond is found on C - F polymer that contains C - CFx (x≤3), C - F1, C - F2, and C - F3 bonds. Between the C - F polymer layer and the silicon substrate, C - C/H, Si - C, Si - O, and Si - F bonds exist. Neither point defect clusters nor distinct planar defects are found in cross-sectional HRTEM images of the silicon substrate. The changes of peak shapes for C, Si, O, and F in the residual film have been analyzed through an in situ resistive anneal under ultrahigh vacuum condition. C - F1, C - F2, and C - F 3 bonds decompose and form C - CFx bonds above 200°C. Above 400°C, C - CFx bonds also decompose to C - C/H bonds. For removal of the silicon surface residue, reactive ion etched specimens have been exposed to O2, NF3, Cl2, and SF6 plasmas. By XPS analysis, NF3 treatment has been revealed to be the most effective. With 10 s exposure to NF3 plasma, the fluorocarbon residue film decomposes and the remaining fluorine is mostly bound to silicon. The fluorine completely disappears after wet cleaning.",
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Characterization and removal of silicon surface residue resulting from CHF3/C2F6 reactive ion etching. / Park, Hyung-Ho; Kwon, Kwang Ho; Lee, Jong Lam; Suh, Kyung Soo; Kwon, Oh Joon; Cho, Kyoung Ik; Park, Sin Chong.

In: Journal of Applied Physics, Vol. 76, No. 8, 01.12.1994, p. 4596-4602.

Research output: Contribution to journalArticle

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AU - Kwon, Kwang Ho

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N2 - The surface properties of an underlying Si substrate after reactive ion etching of SiO2 in CHF3/C2F6 gas plasmas have been studied using x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry, Rutherford backscattering spectroscopy, and high resolution transmission electron microscopy (HRTEM). A 50-nm-thick silicon layer that contains carbon and fluorine and a 4-nm-thick uniform residue layer composed entirely of carbon, fluorine, oxygen, and hydrogen on the silicon surface have been observed. The residue film has nine different kinds of chemical bonds. At the surface, O - F bond is found on C - F polymer that contains C - CFx (x≤3), C - F1, C - F2, and C - F3 bonds. Between the C - F polymer layer and the silicon substrate, C - C/H, Si - C, Si - O, and Si - F bonds exist. Neither point defect clusters nor distinct planar defects are found in cross-sectional HRTEM images of the silicon substrate. The changes of peak shapes for C, Si, O, and F in the residual film have been analyzed through an in situ resistive anneal under ultrahigh vacuum condition. C - F1, C - F2, and C - F 3 bonds decompose and form C - CFx bonds above 200°C. Above 400°C, C - CFx bonds also decompose to C - C/H bonds. For removal of the silicon surface residue, reactive ion etched specimens have been exposed to O2, NF3, Cl2, and SF6 plasmas. By XPS analysis, NF3 treatment has been revealed to be the most effective. With 10 s exposure to NF3 plasma, the fluorocarbon residue film decomposes and the remaining fluorine is mostly bound to silicon. The fluorine completely disappears after wet cleaning.

AB - The surface properties of an underlying Si substrate after reactive ion etching of SiO2 in CHF3/C2F6 gas plasmas have been studied using x-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry, Rutherford backscattering spectroscopy, and high resolution transmission electron microscopy (HRTEM). A 50-nm-thick silicon layer that contains carbon and fluorine and a 4-nm-thick uniform residue layer composed entirely of carbon, fluorine, oxygen, and hydrogen on the silicon surface have been observed. The residue film has nine different kinds of chemical bonds. At the surface, O - F bond is found on C - F polymer that contains C - CFx (x≤3), C - F1, C - F2, and C - F3 bonds. Between the C - F polymer layer and the silicon substrate, C - C/H, Si - C, Si - O, and Si - F bonds exist. Neither point defect clusters nor distinct planar defects are found in cross-sectional HRTEM images of the silicon substrate. The changes of peak shapes for C, Si, O, and F in the residual film have been analyzed through an in situ resistive anneal under ultrahigh vacuum condition. C - F1, C - F2, and C - F 3 bonds decompose and form C - CFx bonds above 200°C. Above 400°C, C - CFx bonds also decompose to C - C/H bonds. For removal of the silicon surface residue, reactive ion etched specimens have been exposed to O2, NF3, Cl2, and SF6 plasmas. By XPS analysis, NF3 treatment has been revealed to be the most effective. With 10 s exposure to NF3 plasma, the fluorocarbon residue film decomposes and the remaining fluorine is mostly bound to silicon. The fluorine completely disappears after wet cleaning.

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