Silicon probing

Silicon Probing

Silicon Sensor Probing

We are in the process of probing the sensors delivered from Hamamatsu and recording their I-V characteristics. The voltage is applied to the backplane of the silicon and the window on the inner guard rail is held at ground. The voltage is raised in 10 volts steps up to 500V. At each step the sensor is allowed settle for 5 seconds. We have decided to probe every 5th sensor (by serial number) so that we examine at least one sensor from each wafer, while at the same time minimising our chances of creating damage.

Results

As of 1st February 2000, we have examined 19 sensors. All conform to the required specifications. 18 of the sensors have currents which are appoximately half that obtained in the faster tests by the manufacturer. 1 sensor has a current four times larger, though it experienced break-down at the same voltage, and in any case was still within the specifications.

All sensors perform excellently and uniformly. This screen dump of output of the test-stand display for 13 sensors which were tested one after each other shows the uniformity of the sensors.

In this magnified plot of the I-V curve for a typical sensor, extremely low currents are observed: at 500 volts, the current is 55 nA.

The response of the slighty poorer sensor is still within spec.


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