SMTA International Conference Proceedings

Comparing Shadow Moiré and Digital Fringe Projection Warpage Metrology Techniques

Authors: Neil Hubble and Leon Weaver
Company: Akrometrix
Date Published: 9/17/2017   Conference: SMTA International

Abstract: Shadow Moiré (SM) remains the most popular metrology approach to measuring surface shapes under dynamic temperature change in the microelectronics industry. Digital Fringe Projection (DFP) is another warpage metrology approach also used in the industry for surface shape over temperature. While some previous studies have compared the techniques, the technology for these technologies has changed over time, thus this study is pursued with implemented improvements in these technologies. Focus is placed on strengths and weaknesses of each technology, and, where applicable, where technology improvements have affected the contrasting strengths and weaknesses of the technology. Specific applications involving unpainted surfaces, discontinuous surfaces, and variable kernel size data smoothing are considered

Warpage measurements are performed in a controlled environment using the same metrology equipment with only the optical metrology changed between the two techniques. Using the same oven for both technologies is critical for warpage comparisons. Under this controlled environment, multiple samples are tested for warpage over temperature in order to show statistical relevance of data between the techniques, as well as find specific examples where the techniques have comparable or dissimilar warpage measurements. Shadow moiré data is processed using a greater camera bit depth than previous studies, along with new software to work with shadow moiré and discontinuous surfaces, historically an area where only DFP could be used to measure across sudden height changes.

Key Words: 

Warpage, metrology, shadow moiré, digital fringe projection

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