Lateral scanning linnik interferometry for large field of view and fast scanning: Wafer bump inspection

Min Y. Kim, Kalyana C. Veluvolu, Soon Geul Lee

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Wafer-level packaging is currently the major trend in semiconductor packaging for miniaturization and high-density integration. To ensure the package reliability, the wafer and substrate bumps utilized as connection junctions need to be in-line inspected as regards their top-height distribution, coplanarity, and volume uniformity. This article proposes a lateral scanning interferometric system for wafer bump shape inspection in three dimensions with a large field of view and fast inspection speed based on an optomechatronic system design. For multiple-peak interferogram from wafer bumps around a transparent film layer, two-step information extraction algorithms are suggested, including top surface profile and underlayer surface profile detection algorithms. The multiple-peak interferogram is acquired with variations of lateral position of the reference mirror by a piezoelectric transducer (PZT). A series of experiments is performed for representative wafer samples with solder and gold bumps, and the effectiveness of the proposed inspection system is verified from the test results.

Original languageEnglish
Pages (from-to)271-285
Number of pages15
JournalInternational Journal of Optomechatronics
Issue number3
StatePublished - Jul 2011


  • 3-D measurement
  • Lateral scanning interferometer
  • Linnik interferometer
  • Semiconductor inspection
  • Wafer bump inspection


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