Ion beam induced charge microscopy studies of power diodes

Abstract

Ion beam induced charge microscopy (IBIC microscopy) has been established recently as ananalytical tool for the characterization of various types of semiconductor devices. In thispaper the potential of IBIC microscopy for the analysis of deeply buried structures of highpower devices under biases of more than 2 kV is discussed. Such data are useful inthe design process of high power devices because excessive fields at device edgeregions or within protection elements (e.g. field ring structures) can be avoided.Since charge collection efficiency within depleted pn junctions is typically 100% for IBIC analysis, the contrastdue to E-field variations within the large depletion regions of high power devices is limited. Here wewill introduce a new approach for enhancing this contrast by using the temporalinformation from the IBIC signals gained with a transient IBIC set-up. Simulations andexperimental data will be compared to evaluate the suitability of the new approach. Thedevice used here is a high voltage diode with a field ring structure which was analysedusing a 2 MeV proton beam.