A novel measurement set up for optical characterization of CMOS photodiodes using immersion oil

This novel measurement method is a very simple but efficient improvement of key optical parameter measurements like spectral responsivity. The real photodiode response without interference fringes resulting from the CMOS backend stack can be measured without the expensive and lengthy introduction of antireflective coatings or post-measurement corrections. In addition, the measurement mimics the actual conditions of the photodiodes in applications much better, since often thick optical coatings in transparent packages are used to suppress interference.