THE CHARACTERISTICS OF CMOS DEVICES IN OXYGEN-IMPLANTED SILICON-ON-INSULATOR STRUCTURES

The characteristics of CMOS devices fabricated in oxygen-implanted silicon-on-insulator (SOI) substrates with different oxygen doses are studied. The results show that transistor junction leakage currents are improved by orders of magnitude when the oxygen dose is decreased from 2. 25 multiplied by 10**1**8 cm** minus **2 to 1. 4 multiplied by 10**1**8 cm** minus **2. The floating-body effect, i. e. , transistor turn-on at lower gate voltage with dramatic improvement in subthreshold slope when the drain voltage is increased, is enhanced by the reduction in leakage current and hence the oxygen dose. In SOI substrates implanted with 1. 4 multiplied by 10**1**8 cm** minus **2 oxygen dose and annealed at 1150 degree C, back-channel mobilities are decreased by several orders of magnitude compared to the mobilities in the precipitate-free silicon film. These device characteristics are correlated with the microstructure at the silicon-buried-oxide interface, which is controlled by oxygen implantation and post-oxygen-implantation anneal.