Ion beam induced charge microscopy studies of power diodes

Abstract

Ion beam induced charge microscopy (IBIC microscopy) has been established recently as an analytical tool for the characterization of various types of semiconductor devices. In this paper the potential of IBIC microscopy for the analysis of deeply buried structures of high power devices under biases of more than 2 kV is discussed. Such data are useful in the design process of high power devices because excessive fields at device edge regions 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 contrast due to E-field variations within the large depletion regions of high power devices is limited. Here we will introduce a new approach for enhancing this contrast by using the temporal information from the IBIC signals gained with a transient IBIC set-up. Simulations and experimental data will be compared to evaluate the suitability of the new approach. The device used here is a high voltage diode with a field ring structure which was analysed using a 2 MeV proton beam.

Semiconductor Characterization by Scanning Ion Beam Induced Charge (IBIC) Microscopy

“…In these experiments, the long range probing depths of MeV protons were exploited to investigate p-n junctions located tens of micrometers below the surface to achieve sufficiently high breakdown voltages of the order of 10 kV [46,47].…”

Ion Beam Analysis: A Century of Exploiting the Electronic and Nuclear Structure of the Atom for Materials Characterisation

“…During an IBIC experiment the charge carriers are generated deep (tens of microns underneath the sample surface) compared with the equivalent electron beam technique (EBIC) which only probes near the surface [117], just under the contact electrode and in some cases not even penetrating the electrode. In contrast, the deep interaction of the ion with the sample has even enabled researchers to probe buried structures in semiconductor devices (power devices [118] and MOS devices [119]). Typical EBIC experiments operate in continuous current mode (compared to pulse-by-pulse or ion-by-ion acquisition of the IBIC signals) and thus cannot analyse the transient current response to each interaction.…”