Comparison of laser voltage probing and mapping results in oversized and minimum size devices of 120 nm and 65 nm technology

Laser voltage probing (LVP) provides signal levels from circuit nodes through the backside of integrated circuits. Previous investigations presented voltage sweeping and modulation mapping, based on CW (continuous wave) 1319 nm laser. In this paper, large device structures have been compared with results of measurements on sub-micron devices – having nominal gate lengths and widths – including a ring oscillator (RO). All signals were obtained with a spectrum analyzer, requiring no internal trigger signals from the circuitry. On ROs, frequency shifts due to the thermal stimulation effect could be determined. Furthermore, a new measurement scheme for sign measurements of LVP signals is introduced.