A study of hot-carrier-induced mismatch drift: a reliability issue for VLSI circuits

The mismatch drift of dynamic circuits, which must be corrected by precharging before activation, is a fundamental process and device reliability issue for very large scale integration (VLSI) circuits. In this paper, we report the consequences of hot-carrier effects on gate capacitance variation and its impact on the mismatch drift of MOS dynamic circuits. It is shown here that the impact of hot-carrier-induced gate capacitance variation on VLSI circuits is more critical than DC parameter (saturation current, threshold voltage, etc.) degradation. An electron beam probing was performed on a 64 Mb DRAM chip to detect the influence of gate capacitance variation in dynamic circuit blocks before and after hot-carrier stress.