PROCESS ALTERNATIVES FOR MANUFACTURING INTEGRATED INDUCTORS

New interest has recently arisen on inductors integrated monolithicall y together with CMOS electronics. The reason for the current attention lies in the demand for higher level of integration and increased oper ation frequency. Earlier efforts to make advantage of inductors in add ition to other passive elements led to conclusion that the high conduc tivity of silicon and the large area required for the device would res trict their use. General development of integrated circuit fabrication technology has now made it possible to reappraise the use of integrat ed inductors. Two important process related aspects which affect the q uality factor of inductors are the series resistance and parasitic cap acitance of the structure. We have worked on reducing the resistance b y using alternative metallization for the inductors and at the same ti me born in mind the demand for integration. We also have tried differe nt oxide thicknesses between silicon substrate and the device to reduc e parasitic capacitance. For alternative metallizations electroplated gold and thick sputter deposited aluminium have been used. Comparison between the quality of inductors as well as manufacturability of each process has been made.