SEM Voltage-To-Phase Contrast Converter
Original Publication Date: 1984-Nov-01
Included in the Prior Art Database: 2005-Feb-05
A voltage-to-phase converter is used in conjunction with a scanning electron microscope (SEM) to visualize, in black and white on a cathode ray tube screen, the in and out of phase voltages with respect to a reference signal in a chip. The phase-dependent voltage contrast method which is used for large-scale integrated (LSI) circuit failure analysis requires a processing of the video signal by means of a phase detection module which is placed between the secondary electron detector control circuit (SDC) and the video detector control circuit (VDC) of a SEM. The light contrast obtained on the screen is proportional to the phase difference between the signals in the chip or device under test (DUT) and a clock signal which is used as a reference signal. All the potentials are visualized with a grey level.