Advanced technique for broadband on-wafer rf device characterization

Abstract

A technique for a broadband 2-port on-wafer RF device characterization is presented. It utilizes advanced LRM+ calibration with standards realized on a Si wafer. The approach relies on three standards: a non-perfect Thru standard, a reflection standard which is symmetrical for both ports and a complex match (Load) standard which can be different for both ports. Models for such kind of standards as well as LRM+ calibration are not supported by currently available VNA firmware. The presented method allows to set up a planar customized calibration kit (e.g. on a Si wafer) which has the same contact pad design as used for an on-wafer DUT. A simple procedure to compensate different DC resistances of port-to-port and set-to-set variation for on-wafer realized Load standards is shown. Additional wafer embedded verification elements as well as real DUT measurement results were used to compare the accuracy of the new method with the state of the art calibration and de-embedding procedure. A good calibration accuracy and significant simplification of RF device characterization procedure has been achieved with the proposed approach.