Full Wafer Probe Stations - Lake Shore Cryotronics, Inc.

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Probe Stations

Full Wafer Probe Stations

Full 4-inch wafer coverage, larger on request
Non-destructive, full-wafer testing
Up to six probe positions
Robust, stable mechanics
Massive base and massive, vibration-isolating legs
Frequencies from dc to 67 GHz can be accommodated
Two microwave cables per probe (for dual probes) available
Probe travel: 125 mm x 51 mm x 16 mm. Retracts easily, even under vacuum!
In-situ and under-vacuum probe planarization (5°)
Wafer travel: 51 mm circular area, larger on request
Wafer rotation: ±5°
High-resolution scope/ CCD camera/video monitor zoom from 5µm ultimate resolution to 12mm x 17mm view (other ranges available)
Windows are IR-absorbing
Continuous transfer cryogenics provides fast, efficient cool-down, uses either helium or nitrogen, vents away from sensitive equipment
Wide-range turbo-pumped vacuum provides fast, hydrocarbon-free pumpdown
Vacuum system is electrically and mechanically isolated from vacuum shroud of system
Wafer temperature stability: 0.05 K
Temperatures from 4.5 K to 475 K
Probe temperature controlled to near wafer temperature
Camera manipulation covers full 4-inch wafer, retracts to allow access to vacuum chamber, and lifts up an additional 200 mm for wide-angle optics
Probe cards, wedges supported

Choose one of the products below to customize a system to meet your needs.

4 Manipulated Stage System
6 Manipulated Stage System

Sample Holders

Each probe system comes with one grounded sample holder. Additional sample holders are available in grounded, isolated, coaxial, and triaxial configurations at additional cost. Coaxial and triaxial sample holders require a separate triax feedthrough installation for proper measurement and biasing. Shown here.

Probes: Model ZN50

The Model ZN50 probe is a 50 -impedance stripline probe, and is shown below (left side). In probe systems built by Desert Cryogenics, probes are cooled to eliminate heat injected at the probe contacts. The ZN50 probes are ideal for a very broad array of applications including: dc biasing, low-frequency transport measurements; low-noise shielded measurements; low-leakage guarded measurements; and high-frequency measurements to 2 GHz (standard) or 5 GHz (HF option). Four available tip radii are ideal for: contacting pads (25, 50, 100, 200 µm tip); contacting large features (10 µm tip); contacting small features (3 µm tip). Tip materials are available in Tungsten (W), Beryllium Copper (BeCu), and Paliney 7, (Au alloy). To specify tip diameter and material, add the diameter in microns to the model number, and then the material abbreviation. I.e.- ZN50-25-BeCu.

Probes with the HF option have an increased bandwidth of 5 GHz. HF probes and probes with a 10 µm tip incorporate a more compliant tungsten wire to minimize tip damage. To specify the HF option, add -HF to the model number. For example, a probe with 3 µm tip radius (extremely sharp) and HF option has model number ZN50-03-BeCu-HF.

An SMA jack connects directly to metallization on the alumina blade. This provides optimal performance in the low-frequency microwave range up to 3 GHz. The probe tips are soldered directly to the thick film printing on the signal side of the alumina blade. This can only be soldered reliably one time, therefore the blades are designed to be replaceable as an assembly.

Spare or replacement units, are configured as above, inserting an R after the ZN50, and specifying the radius and tip material as follows in example. I.e.- a ZN50-25-BeCu replacement or spare blade would be a ZNR-BeCu-25. Each tip comes in its own box and is clearly marked, for exchanging tip materials and sizes.

Microwave Probes

Microwave probes are made to Desert Cryogenics' specifications to optimize cryogenic performance. These customized probes have minimal thermal mass in order to reduce the time needed for the probe temperature to stabilize. Soft copper braids are installed to allow the probes to be cooled to minimize heat injected at the device under test. In addition, probes have low-thermal-conductance tips to further reduce heat injection. Probes are available for work to 40 GHz, 50 GHz, and 67 GHz, and with a range of pitches. An optional ±5° Theta rotation mechanism allows in-situ planarization of microwave probes.

Probes: Optical and Custom

In addition to windows and optical access, fibers can be manipulated to transmit or receive light or IR/UV radiation. Custom probes for other applications are available on request.

Cables

The cables offered depend on the application and experimental needs. Simple wires are offered for dc bias. Micro-coax with an SMA connection at the probe end and BNC or triax feedthroughs are offered for shielded or guarded work. Semi-rigid coax with SMA connections at both ends and compression-sealed vacuum feedthroughs are offered for work to 5 GHz with the Z50 probes. A range of semi-rigid cables with microwave connections and compression-sealed vacuum feedthroughs are offered for the microwave probes. The choice of cable and connection depends on the required bandwidth and the trade-off between thermal loss and cable microwave loss.

Stages: The Heart of Manipulation

Manipulation of in-vacuum probes with stages in the ambient environment introduces requirements on the stages not typically met with commercial stages. The loads introduced by the vacuum forces through the edge-welded bellows can be very significant. Desert Cryogenics designs and builds stages optimized for cryogenic probing. The stages for the Full Wafer Probe Systems have a travel of 125 mm in the axis of the bellows (X-axis), 51 mm horizontally (Y-axis), and 16 mm to lift and lower the probe (Z-axis). The Wafer Stage is also manipulated by 52 mm in both an X and Y axis for reaching any position on a 4" wafer with all probes. Theta, +/- 5°, for pattern alignment is also provided. The x-axis stage has a 2-mm pitch and 50-mm knob with tics at each 20 µm, providing 1-µm resolution and swift, effortless adjustment even when loaded by vacuum. The Y- and Z-axis stages have 0.5 mm pitch with positive, zero-backlash micrometer drive (no springs). Shown here.

Optics Packages

The standard Zoom 70 optics package from Desert Cryogenics does not require the user to lean over the system and peer into eyepieces. A CCD camera on the top of an optimized monoscope sends the image to a high-resolution video monitor which can be viewed from anywhere near the system. The optics can be manipulated to view any part of a 2-inch wafer, and in addition, can be retracted and swung away to allow access to the top of the vacuum shroud. The illumination is coaxial. The standard monoscope has a zoom ratio of 7:1 and an ultimate resolution of 5 µm. A 12.5:1 zoom, or 16:1 zoom upgrade, is available with resolution of up to 4 µm* and to 3 µm* respectively.
*field systems with extended chamber heights may vary, decreasing resolution.

Available Vacuum Systems

The available vacuum system package includes an integrated turbo system for fast, hydrocarbon-free pumpdown. A cold cathode gauge, and Pirani gauge, display the level of the vacuum, from atmosphere to 10-6 Torr. Stainless steel flex lines isolate pump vibrations from the system, and an electrical break isolates the pump system electrically from the Faraday cage of the manipulation system. The turbo is robust, and vents itself upon shutdown, making it easier to operate.

Manipulated, Full Wafer Systems are comprised of a collection of modular subsystems, which can be selected as needed for a given application. Start with the basic 4 or 6 stage configuration, vacuum chamber, refrigerator and temperature controls, massive base and vibration absorbing legs. Populate any number of probe positions up to six or choose a probe card instead. Configure the type or types of probes and cables needed for each probe position to achieve your measurement goals.