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I
Z
I
Probe
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Overview
The IZI
Probe has significant differences when compared to other RF probes. Unlike coaxial probes, the IZI Probe utilizes
long spring-like nickel contacts that act like cantilever needles. These contacts touch down independently on the wafer
surface, ensuring excellent test results on both even and uneven surfaces.
Minimal overtravel is required in order to ensure
repeatable contact. The unique design guarantees unparalleled contact reliability and makes the probe exceptionally easy
to handle and align. The IZI
Probe, however, is handled slightly differently than a standard RF probe, and it is important to
understand and follow the recommendations described here.
Mounting the Probe on the Positioner
The IZI
Probe can be mounted onto any industry standard positioner arm. Once mounted, position the arm parallel to the
wafer surface.
Contact and Alignment
Use the positioner z-axis to lower the probe tips. Use a high resolution microscope to view each tip as it touches down
independently on the wafer surface (parallel contacts will touch down in unison on a planar surface). Position the probe and
probe arm parallel to the wafer surface. Contact has been achieved when the tips skate slightly forward. Additional
downward z-movement after this first contact is called overtravel. It is important that the probe is poitioned at the correct
angle to the aligned substrate (see graphics below). The the probe arm fixing screws can be used to make slight
adjustments in the angle of the probe in relation to the substrate structures.
Overtravel
The IZI
Probe requires very little overtravel for reliable contact. Recommended overtravel is 5
μ
m on gold and 30
μ
m on
aluminum pads. For extremely non-planar surfaces (up to 50
μ
m pad height differences or differing wafer topographies),
more overtravel may be required; some models can withstand an overtravel up to 200
μ
m. However, using the
recommended overtravel will help avoid damage to your DUT. The minimal skate requirements of the IZI
Probe enable
accurate positioning on very small pads. The independent spring fingers enable consistent contact on uneven surfaces or
through vibration interference, even with low overtravel values.
W
ARNING
Too much overtravel can damage the wafer and significantly shorten the life span of the probe.
Note that the IZI
Probe contacts are typically 10
μ
m behind the shadow of the probe tip.
It is important that the IZI
Probe contacts the wafer directly on the pad surface. Early contact is typically caused by using too
much overtravel during alignment, and can result in the scraping away of the pad metal from the side. Too much overtravel
can destroy the calibration standards pads.
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Quick Reference Guide
I
Z
I
Probe