Non-destructive monitoring of planarization processes [CMOS technology]

A novel technique for control and optimization of planarization processes is presented. The method is called the DOPED contactless method and is based on analysis of the diffraction of light by a periodic grating for the control of the reproducibility of certain planarization processes: (i) oxide sidewall spacers, (ii) oxide deposition and etchback, and (iii) etchback of a sacrificial polymeric layer. This simple nondestructive method allows the reproducibility of the processes to be monitored and the achieved profiles after planarization to be quantified geometrically after calibration. It is shown how, for each planarizing scheme investigated, the DOPED measurement is related to the relevant geometrical parameters which describe the degree of planarization