Effects of chamber wall conditions on Cl concentration and Si etch rate uniformity in plasma etching reactors

Tae Won Kim, Eray Aydil

Research output: Contribution to journalArticle

Abstract

Experimental measurements of the etch rate and ion flux distributions on the wafer are combined with modeling to elucidate the effects of reactor wall conditions on Cl concentration and polysilicon etch rate uniformity in an inductively coupled plasma etching reactor. The spatially averaged etch rate across the wafer increases with time as etch products react with residual oxygen in the chamber and coat the reactor walls with a thin layer of silicon oxychloride film. Chlorine concentration in the plasma and the Si etch rate increase due to lower recombination probability of Cl on this film as compared to the "clean" anodized aluminum wall surface. Etch rate is highest at the wafer center when the walls are maintained in the clean state. In contrast, the etch rate peaks at the wafer edges when the walls are coated with the silicon oxychloride film. The drift in etch rate and uniformity is primarily due to a drift in Cl concentration and its spatial distribution. As the reactor walls are coated, the etch rate distribution changes from a center-fast profile to an edge-fast profile due to a change in the dominant Cl depletion mechanism from wall recombination to recombination on the wafer surface.

Original languageEnglish (US)
JournalJournal of the Electrochemical Society
Volume150
Issue number7
DOIs
StatePublished - Jul 1 2003

Fingerprint

Plasma etching
plasma etching
chambers
reactors
Silicon
wafers
Chlorine
Inductively coupled plasma
Aluminum
Polysilicon
Spatial distribution
silicon films
Ions
Oxygen
Fluxes
Plasmas
profiles
chlorine
spatial distribution
depletion

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Condensed Matter Physics
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

Cite this

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abstract = "Experimental measurements of the etch rate and ion flux distributions on the wafer are combined with modeling to elucidate the effects of reactor wall conditions on Cl concentration and polysilicon etch rate uniformity in an inductively coupled plasma etching reactor. The spatially averaged etch rate across the wafer increases with time as etch products react with residual oxygen in the chamber and coat the reactor walls with a thin layer of silicon oxychloride film. Chlorine concentration in the plasma and the Si etch rate increase due to lower recombination probability of Cl on this film as compared to the {"}clean{"} anodized aluminum wall surface. Etch rate is highest at the wafer center when the walls are maintained in the clean state. In contrast, the etch rate peaks at the wafer edges when the walls are coated with the silicon oxychloride film. The drift in etch rate and uniformity is primarily due to a drift in Cl concentration and its spatial distribution. As the reactor walls are coated, the etch rate distribution changes from a center-fast profile to an edge-fast profile due to a change in the dominant Cl depletion mechanism from wall recombination to recombination on the wafer surface.",
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