Automated Measurement Procedures of Three-Port and Four-Port Devices on Silicon Wafers

The development of telecommunication networks and wireless systems has led to a continually increasing market for RF integrated circuits. The CMOS and BiCMOS silicon technologies are particularly attractive for the fabrication of these circuits because of the good performance of their transistors coupled with the low cost of production. They allow the development of very complex RF integrated circuits (RF-VLSI) and open the gate to future systems on chip. Simulation of these advanced circuits requires high frequency characterization of elementary two-port devices. Nevertheless three-port and four-port measurements will represent a very interesting tool for characterization of active components like BJTs or MOSFETs, passive components like tees and crosses, or for characterization of crosstalk and coupling. A new method which allows measurements of three-port and four-port devices for the specific case of silicon wafer in an industrial environment has been developed. This procedure is based on the use of coaxial loads, microwave switches and it requires several SOLT calibrations. On wafer and off wafer parasitic elements have been analyzed and their effects on measurements are taken into account. The equipment, the measurement principle and the different steps of correction are presented in this paper. Finally, the procedure has been validated on experimental measurements of advanced MOSFETs and BJTs. Very satisfactory results have been obtained and BJT characterization is presented as an example.