Limitations of the CV technique for ion-implanted profiles

The CV profiling technique is reviewed and its validity and limitations are investigated, with special attention given to the case where the method is extended to the study of ion-implanted impurity distributions. A theoretical analysis is described which yields information about the dependence of CV measurements on impurity profile. The inverse problem is then considered and the results demonstrate that the depletion approximation formulas commonly used for the reduction of CV data to give doping profiles are misleading when applied to substrates with rapidly varying profiles as are generally the case for ion-implanted substrates. Examples of the profiles obtained for various shaped impurity distributions are given.