Characterization of CMOS devices for VLSI

CMOS bulk and SOS technologies are discussed for VLSI with emphasis on static and dynamic characteristics of two-input NAND gates. Optimum performance (minimum figure of merit FM = tpdPd) is obtained for a CMOS/SOS two-input NAND gate (FO = 2, CL= 22 fF) with an electrical channel length L = 0.75 µm, channel width W = 5.0 µm, and oxide thickness Xo= 450 Å with VDD= 3.0 V, to yield tpd= 400 ps and Pd= 250 µW (tpdPd= 100 fJ) at room temperature. Bulk technology performs within a factor of 2 of SOS for tpdand Pd. CMOS technologies offer subnanosecond propagation delays, similar to ECL bipolar, at the low submilliwatt power levels of CMOS. An analytical expression for tpddescribes the performance of two-input NAND gates in terms of device modeling and fabrication parameters. Such an expression provides a hierarchial modeling approach to characterize minicells for VLSI.