Farrokh Mohammadi

Effect of scaling of interconnections on the time delay of VLSI circuits

Effect of scaling of dimensions, i.e., increase in chip size and decrease in minimum feature size, on the RC time delay associated with interconnections in VLSICs has been investigated. Analytical expressions have been developed to relate this time delay to various elements of technology, i.e., interconnection material, minimum feature size, chip area, length of the interconnect, etc. Empirical expressions to predict the trends of the technological elements as a function of chronological time have been developed. Calculations of time delay for interconnections made of poly-Si, WSi 2 , W, and Al have been done and they indicate that as the chip area is increased and other device-related dimensions are decreased the interconnection time delay becomes significant compared to the device time delay and in extreme cases dominates the chip performance.

Effect of Scaling of Interconnections on the Time Delay of VLSI Circuits

Effect of scaling of dimensions, i.e., increase in chip size and decrease in minimum feature size, on the RC time delay associated with interconnections in VLSICs has been investigated. Analytical expressions have been developed to relate this time delay to various elements of technology, i.e., interconnection material, minimum feature size, chip area, length of the interconnect, etc. Empirical expressions to predict the trends of the technological elements as a function of chronological time have been developed. Calculations of time delay for interconnections made of poly-Si, WSi2, W, and Al have been done and they indicate that as the chip area is increased and other device-related dimensions are decreased the interconnection time delay becomes significant compared to the device time delay and in extreme cases dominates the chip performance.

N-Channel MOSFETs with WSi 2 gate

Tungsten silicide gate depletion- and enhancement-mode NMOS transistors were fabricated. The transistor characteristics revealed the excellent compatability of WSi2as gate electrode for MOS integrated circuits. Electron mobility of channel at saturation were found to be 210 cm2/v sec for enhancement-mode transistor and 110 cm2/v sec for depletion-mode transistor.