Metrology for Measuring Bumps in a Protection Layer Based on Phase Shifting Fringe Projection

Abstract

We developed a telecentric 3D measurement system based on the fringe projection technique to measure phases corresponding to the 3D shape of bumps on a surface. A measurement algorithm based on an area scan camera with a flexibly programmable region of interest (ROI) was applied to reconstruct the 3D model. Only the pixel information within the ROI is stored, which reduces the data volume and processing and accelerates the area scan acquisition. Experiments showed that the fringe projection system provided good linearity between the calibration and optical data with excellent accuracy. A reflectometry sensor was implemented to provide a correction offset to the bump height in a protection layer in a subsequent high-speed inspection.

Keywords

• phase-shifting
• fringe projection
• reflectometer
• protection layer
• bumps