Measurement of punch-through voltage

Measurements performed by Alex Chilingarov, University of Lancaster

Description of the measurement

The punch through voltage is measured by applying a voltage between the bias rail and the strip implant via the DC pad. Plotting dU/dI should in normal operation give the value of the bias resistance. When the voltage difference between the implant and the bias rail is sufficiently large a break-down will occur between the end of the strip and the bias rail. This is seen as a sudden change of the dU/dI graph. This voltage is called the punch-through voltage and the mechanism will ensure that the potential of the implant will not deviate too much from GND.

Results from measurements of w14

The graph below shows dU/dI versus the voltage difference between the bias rail and implant. For low voltages the measured bias resistor value is consistent with values expected from production. The punch through occurs at 12-14 volts, which is compatible with values measured for non-processed sensors.

-- LarsEklund - 06 Apr 2009