A New Step In The Electrical Characterisation Of Silicon-Insulator Interfaces

The principle of charge pumping (CP), the most widely used semiconductor-insulator interface traps electrical characterisation method, is recalled first. Then, a rigorous model proposed recently for this technique is summarised. A CP technique proposed a few years ago is also presented. Assuming tunnelling for the capture of carriers, the trap depth concentration profiles, from the Si-SiO₂ interface towards the oxide bulk extraction can be extracted. Combining these two approaches, i.e. accounting for the trap depth distribution in the rigorous CP model allows for the first time to simulate CP curves in all experimental conditions. The curves obtained are compared with experimental results. It is shown that information on the trap properties can be obtained from the differences between both curve types. The generalised CP model enables to know the energy and depth region of the oxide probed in all the experimental conditions. A new spectroscopic CP technique is also presented. Based on the frequency dependence of the CP curves, it allows to evidence and to study the traps at the Si-SiO₂ interface. The traps in the oxide can also be studied independently. The simulations exhibit again the same features as the experimental curves do. Again, trap characteristics can be obtained from the differences between both curve types.