A compact and sensitive two-dimensional angle probe for flatness measurement of large silicon wafers

Wei Gao, Peisen S. Huang, Tomohiko Yamada, Satoshi Kiyono

Research output: Contribution to journalArticlepeer-review

85 Citations (Scopus)


A two-dimensional (2D) angle probe was developed to realize a new scanning multi-probe instrument employing 2D angle probes for flatness measurement of large silicon wafers. Each probe, which utilizes the principle of autocollimation, detects the 2D local slope components of a point on the wafer surface. The 2D local slopes (angles) are obtained through detecting the corresponding 2D positions of the reflected light spot on the focal plane of the object lens using position-sensing devices (PSDs). To make the probe compact in size, it is more effective to improve the sensitivity of angle detection by selecting proper PSDs than using an objective lens with a larger focal distance. Two kinds of photo devices, linear lateral effect PSDs and quadrant photodiodes (QPD), for sensing 2D positions were discussed theoretically and experimentally. It was shown that a QPD is the best for highly sensitive 2D angle detection. In the experiments, a compact prototype angle probe with dimensions 90(L) mm × 60(W) mm × 30(H) mm employing a QPD as the PSD was confirmed to have a resolution of approximately 0.01 arc-second.

Original languageEnglish
Pages (from-to)396-404
Number of pages9
JournalPrecision Engineering
Issue number4
Publication statusPublished - 2002 Oct


  • Angle probe
  • Autocollimator
  • Error-separation
  • Flatness
  • Local slope
  • Measurement
  • Quadrant photodiode
  • Sensitivity
  • Silicon wafer
  • Slope probe
  • Surface profile
  • Two-dimensional

ASJC Scopus subject areas

  • Engineering(all)


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