High throughput test stand (HTTS)

High throughput test stand (HTTS)

The high throughput test stand (HTTS) is a custom made unit, specially designed for the rapid characterization of thin film materials libraries which in our case are commonly deposited on 4” Si-wafers.

Depending on the installed measurement module, electrical or magnetical properties of the materials library can be measured. A x-y table allows the scanning of the library with a laterial resolution down to a few tens of microns in a defined coordinate system, so different measurements at the same locations can be linked to each other. The samples are placed on a temperature controlled stage, so all measurements can be done over a wide temperature range, ranging from minimum temperatures of -100°C (using liquid nitrogen) up to a maximum temperature of +300°C. To avoid frost on the sample at low temperatures, the measurement table is enclosed in a box which is flooded with nitrogen during the measurement.

Electrical properties are measured using custom made four-point probeheads with spring loaded pins. The distance between the pins is 0.5mm, so the lateral resolution of the measurement is below 1mm. Special probeheads have up to 20 pins which can be addressed via a switching matrix to achieve even higher throughput. Temperature-dependent resistance measurements are, for example, ideally suited for measuring the transformation behaviour of shape-memory alloys.

Magnetic measurements are being performed using a MOKE setup with an electromagnet having a strength of approximately 0.3T. During these measurements, temperature-cycling is also possible. Since the electromagnet can be used simultaneously with the four-point probeheads, magnetoresistance measurements can also be done with the system.

When using a laser based distance sensor (resolution of 5µm) temperature-dependent measurements of materials libraries on cantilevers can be performed, where the deflection of the cantilevers during temperature cycling is monitored. The cantilevers’ deflection is due to stress which builds up for example during a phase transformation.

All measurements are automated; programming has been done using LabView.