F. Roullier, J. P. Blanvillain, NXP Semiconductors, Caen, France; B. Domengès, CNRT-CNRS, Caen, France

Summary: This paper deals with real-time FTIR etch depth measurements performed on passive integrated silicon substrates. High-density trench capacitors are non-destructively characterized using FTIR Michelson type spectrometer. Based on effective medium approximations, an effective index associated to the capacitor layer is introduced which allow a good evaluation of the capacitor hole depth. Obtained results correlate well with those from SEM measurements performed on cross-sections, on a range going from 12µm to 30µm depth.