Probe Station Use

WARNING:

Probe tips are very delicate and expensive. It is easy to damage the tips. If you accidentally drive them into your sample (or the vacuum chuck) they will bend and develop a hook at the end. Hooked probes can damage your sample and/or make a poor contact to your devices, so be careful when moving or lowering the tips.

ORIENTATION:

A sketch of one of our probe stations (REL-4100) is shown in figure 1. For the purposes of this discussion, we will focus on the vacuum chuck (it holds the sample down), the platen (this is the piece that the probers rest on), the micropositioners (usually called a “probers” – used to make electrical contact to – or probe – our devices) and the platen lift lever (used to raise the platen which, in turn, raises all the probers from the sample.

There are also two large knobs on the base of the probe station – the y-motion drive and x-motion drive. With these knobs, you can easily move the sample around while observing it with the microscope. YOU MUST LIFT THE PLATEN BEFORE MOVING THE SAMPLE WITH THE X- OR Y-MOTION DRIVES, OTHERWISE YOU WILL DAMAGE THE PROBE NEEDLES.

The type of prober that we have is shown in figure 2. The probe tip is held in the end of a long arm (the probe arm/probe holder assembly). The arm and its tip can be manipulated using the four knobs on the prober. There are three fine adjustment knobs ( the `x', `y' and `z' motion controls ) and a coarse one (gross `z' motion control).

POSITIONING THE PROBE TIPS ON THE SAMPLE:

1. Raise the probe tip by backing off the gross `z' motion control for each prober on the platen. Raise the tips far enough so that they will not touch the sample or vacuum chuck when the platen is lower all the way. Also make sure that the fine x, y, and z controls are not fully extended in either direction.

2. Lower the platen all the way.

3. Position the chosen device in the field of view of the microscope.

4. Position each prober in the approximate location by moving the whole prober. Lower the probe tip with the gross `z' motion control watching from the side, not through the microscope, until it is close to the sample.

5. Now use the `x', `y' and `z' motion controls to position the probe tips. First concentrate on the `x' and `y' directions, then lower the tip using the `z' motion control. You will notice that the tip drifts in one direction. When the tip touches the surface, you will see the tip move in the other (usually) direction. Repeat for each probe.

6. Perform measurements.

7. If the chip has been patterned with a number of the same devices, all of the devices can be probed without movement of the individual probers. Simply lift the probe tips by lifting the platen, move the sample using the y- and x-motion drives, then lower the platen to contact the next device.