P 8 XL Automatic Wafer

The Tel P 8 XL is an automatic wafer prober.^{[1][2][3][4][5]}

After alignment, the chuck steps the wafer so that each die is brought under the probe card. The probe card contains an array of fine needles that contact the die's bond pads, routing signals between the die and the tester. The prober then signals the tester to perform measurements.

Once testing is complete for a die, the chuck moves to the next die. The process repeats across the entire wafer. After all dies are tested, the wafer is returned to the cassette and the next wafer is loaded automatically.

The automatic wafer prober sits in the test floor of a semiconductor fab after wafer fabrication and before dicing and packaging. At this point, the wafer contains completed integrated circuits that must be electrically verified.

Upstream processes include photolithography, etching, deposition, and planarization. Downstream processes include wafer dicing, die attach, wire bonding, and final packaging. The prober tests each die and records pass/fail data that is used to guide die selection and to monitor process yield.

The primary application of automatic wafer probers is sort test (also called wafer sort or circuit probe). In sort test, the prober performs parametric tests (voltage, current, timing) and functional tests on each die to identify known good die (KGD) before packaging.