Full-field wafer level thin film stress measurement by phase-stepping shadow Moiré

Kuo Shen Chen, Terry Yuan Fang Chen, Chia Cheng Chuang, I. Kuan Lin

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

A wafer topography measurement system has been designed and demonstrated based on shadow Moiré. Three-step phase-stepping and phase unwarping techniques are also incorporated to enhance the system resolution. Wafer curvatures or bows can be achieved by analyzing the Moiré fringe patterns and film stress can be obtained subsequently by transforming this wafer curvature using a conversion equation such as Stoney's formula. Wafer bow of plasma enhanced chemical vapor deposition nitride and oxide coated wafers are measured by this shadow Moiré system and are subsequently verified by the KLA-Tencor FLX 2320 system. The discrepancy between both bow measurements is within 2 μm, regardless of the magnitude of the measurement. Therefore, this system is especially suitable for stress characterization of thicker, stiffer, or highly stressed films. In comparison with the traditional laser scanning method, wafer curvature obtained by shadow Moiré is based on full-field information and it would have a better accuracy. By integrating this system with a more accurate wafer curvature to film stress conversion formula, this system should also provide a better film stress characterization.

Original languageEnglish
Pages (from-to)594-601
Number of pages8
JournalIEEE Transactions on Components and Packaging Technologies
Volume27
Issue number3
DOIs
Publication statusPublished - 2004 Sep

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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