Far infrared Fizeau interferometry is devleoped and it is proposed as a tool for warpage measuremnt of microelectronics devices. The method provides a whole-field map of surface topography. Its basic sensitivity is 5.3 #mu#m per fringe contour and a higher sensitivity is achieved by employing the O/DFM method. The method is implemented by a compact apparatus using a computer controlled environmental chamber for real-time measurement. The method retains the simplicity of classical interferometry while providing a wide applicability to dielectric rough surfaces. Roughness tolerance is achieved by utilizing a far infrared light (#lambda#=10.6 #mu#m). The detailed optical and mechanical configuration is described and selected applications are presented to demonstrate the applicability. The unique advantages of the method are discussed.
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