Characterization of Surface and Sub- Surface Defects on Devices using Complimentary Techniques

Being able to differentiate surface from bulk defects on devices requires the use of complimentary characterization tools. In this article, we show how light microscopy, scanning electron microscopy, energy dispersive X-ray analysis, and time of flight secondary ion mass spectrometry provides complimentary information about the surface and sub-surface composition, topography, and microstructure of a semiconductor device. To create a gamma-ray spectroscopy detector, electrical contacts consisting of a blanket coated cathode and a pixilated anode can be deposited directly on opposite faces of a cadmium zinc telluride (CZT) crystal. The contact metallization must adhere to the surfaces, and the streets between adjacent anode pads must be free of residual metal and contaminants to avoid excessive interpixel leakage currents. The analysis reported below was used to validate the structure and composition of the contact metal stack and to characterize the streets of the anode pad array.