Surface deposition of ionic contaminants on silicon wafers in a cleanroom environment

I. Kai Lin*, Hsun-Ling Bai, Bi Jun Wu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The adsorption and desorption behaviors of ionic micro-contaminants on the silicon wafers in a cleanroom environment were investigated in this study. The experimental measurements showed that the surface density of ionic contaminants was significantly affected by both the exposure time and the properties of contaminants. The rate parameters of a kinetic model for surface deposition were determined by numerical optimization of fitting the experimental data on surface and ambient concentrations of airborne molecular contaminants (AMCs). Subsequently, the time-dependent deposition velocity and sticking coefficient of ionic species were obtained. The results showed that ${\rm F}{-}$, ${\rm Cl}{-}$, ${\rm NO}-{3}{-}$, ${\rm SO}-{4}{2-}$, ${\rm Na}{+}$, ${\rm NH}-{4}{+}$, ${\rm K}{+}$, and ${\rm Mg}{2+}$ were the major ionic microcontamination species on the wafer surfaces, with the adsorption rate constant and the sticking coefficient of ${\rm K}{+}$ ion being larger than those of other ionic contaminants. After the determination of sticking coefficients, the allowable wafer exposure durations and the maximum ambient concentrations of ionic species were exemplified based on the guideline recommended by the International Technology Roadmap for Semiconductors (ITRS).

Original languageEnglish
Article number4909530
Pages (from-to)321-327
Number of pages7
JournalIEEE Transactions on Semiconductor Manufacturing
Volume22
Issue number2
DOIs
StatePublished - 1 May 2009

Keywords

  • Adsorption and desorption
  • airborne molecular contaminants (AMCs)
  • cleanroom
  • microcontamination
  • sticking coefficient
  • Wafer deposition

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