18
CHAPTER 2:
System Overview
Model CRX-6.5K Probe Station
2.3.2.3 ZN50-Compatible Probe Mount
All ZN50 series blades require a ZN50-26U probe mount that attaches to the probe
arm and provides mechanical support and thermal anchoring for the blade. The probe
mount braids provide the thermal anchoring. They can be connected to or
disconnected from the sample stage as desired for a particular measurement
application. When they are connected, the probe is maintained at approximately the
same temperature as the anchor point.
2.3.3 Microwave Probe
Configurations
Matching microwave probes and cables are available in three frequency ranges: DC to
40 GHz, DC to 50 GHz and DC to 67 GHz. Each frequency range uses a different
connector type, but all use the same semirigid coaxial cable. Probe arm planarization
is necessary to ensure simultaneous contact of all three points of the microwave
probe tip. A planarization assembly is included on micro-manipulated stages when
microwave cables are ordered, or it can be field installed.
2.3.3.1 Microwave-Compatible Probes
There are three frequency configurations of microwave probes, determined by the
connector used. The microwave probe must be specified with the same frequency and
connector type as the probe cable. All microwave probes are constructed with
ground-signal-ground (GSG) geometry and are designed for use with coplanar
waveguides. The BeCu signal and ground points are 10 µm to 12 µm planar triangular
structures. The pitch or spacing between the probe points can be specified from
50 µm to 250 µm in 50 µm increments. In general, smaller pitches are recommended
for higher frequency applications. The point size is the same regardless of the probe
pitch. The probes have a room temperature current limit of 2 A due to heat generated
in the probe tip. Consult Lake Shore if this current limit is not sufficient for your
application.
Separate probe mounts are not necessary for microwave probes because they are
permanently mounted into a proprietary probe body. The proprietary microwave
probe body is optimized for thermal performance in cryogenic probe stations and
includes both mechanical support and thermal anchoring for the probe.
Microwave probe bodies must be kept below 350 K at all times, but due to the low
thermal cross section of the probe points, the probe tips can safely probe substrates
that are higher in temperature.
FIGURE 2-13
Approximate
shape of microwave probe tip
G
G
S
FIGURE 2-14
Microwave probe
