Low-loss CPW lines on surface stabilized high-resistivity silicon

This letter proposes a solution to the surface conduction problem in silico n monolithic microwave integrated circuits (MMIC's). An LPCVD polycrystalli ne silicon layer is deposited over the surface of a high-resistivity silico n wafer which is then covered with a silicon dioxide layer. The polycrystal line silicon layer effectively removes, through traps, any free electrons o r holes that may have been induced at the oxide-silicon interface. The CPW lines with 1.25-mu m aluminum metallization on passivated HRS substrates ha ve an attenuation loss at 30 GHz of only 1.08 dB/cm.