Full automatic homemade probestation for detector testing

QTC probestation

The sensor is held down by vacuum on an full automatic x,y,z + rotation stage, controlled by a PC with Labview. The bias voltage is constantly supplied during the measurement, by a selfmade probe, with dimensional adjustments, which travels with the chuck.
As many probes as needed for the different measurements are placed on both sides of the moving chuck, on special flat metal platforms, which can be adjusted in height or easily be removed. This scheme enable us to circumvent the advantage of probecards, since we need more movements but don't loose time ramping up and down the bias voltage.
The whole apparatus is quite flexible, because we are not fixed to some special geometry; the probes can be placed in nearly every arrangement.
We are using coaxial relays to switch between different measurements to save the pads from too many probe touches (16 relays per station).
Switching between IV, CV, strip leakage current, poly resistors, interstrip resistance, interstrip capacitance, coupling capacitance, current over dielectricum with voltage applied, calibration with precision capacitors is possible.

Here you see a picture of our second probestation, which is used for the measurements of the irradiated sensors.

IQC probestation
Here you see one of our homemade switchbox.

Coaxial relay box.
As a backup, we have another manual station, which is mostly used for inspection, but instruments for IV exists.

Backup manual probestation

We have a common chuck for both probestations. It can be cooled down to -15°C. A thermal isolation insulates the low temperature to the sensor support, which consist of a thin PCB with copper coating. Surrounding the device under test is a ledge with many holes, spilling (cold) dry air onto the sensor to avoid condensation. The vacuum scheme supports 4 different channels, to support simple diodes of small area, sensors up to 60x60mm2 and large wafers up to full 6" size; a special line is implemented for rectangular sensors, which can be switched of for wedge shape devices. This enable us to test all different geometries for CMS, all still open vacuum channels will be covered by a special designed thin piece of stesalit. The chuck by itself is hold by vacuum to allow fast change and equal flatness.
Fixing for a chuck supporting double sided sensors is implemented.

The Chuck

Air is spilled onto the Detector

Frank Hartmann, Frank.Hartmann@cern.ch

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