Analysis of interconnection delay on very high-speed LSI/VLSI chips using an MIS microstrip line model

Using an MIS (metal-insulator-semiconductor) microstrip-line model for interconnection and its equivalent circuit representation, on-chip interconnection delay in very high-speed LSI/VLSI\´s is analyzed in the time domain, changing interconnection geometry, substrate resistivity, and terminal conditions. The results show the following: 1) the "lumped capacitance" approximation is inapplicable for interconnections in very high-speed LSI/VLSI\´s (tpdof below 100-200 ps); 2) as compared to the semi-insulating substrate, the presence of the slow-wave mode and mode transition in the semiconducting substrates causes 1.5-2 times increase in the delay time and 2-10 times increase in the rise time; and 3) in order to realize propagation delay times of less than 100 ps per gate at LSI/VLSI levels, the effective signal source resistance of the gate should be less than 500 Ω so as to long interconnections.