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Universal Probe with ResTest Meter

The Universal Probe combined with the ResTest Test Unit is a unique system for general purpose use as well as for certain special applications.

About the Jandel ResTest Four Point Probe

  • Constant current source and meter for use in making the four point probe measurement.
  • Measurement range: 10 milliohms-ohms-per-square to 10^6 ohms-per-square
  • Displays either sheet resistance or volume resistivity.
  • Save data using:
    • PC connection
    • Up to 99 measurements can be stored internally, or
    • USB memory stick
  • Accommodates either linear or square array probes and 6 choices of probe tip spacings
  • Supports four measurements types:
    •   Sheet Resistance – Primary measurement value is display in Ohms/Square
    •   Wafer Resistivity – Primary measurement value is display in Ohms/Cm
    •   Volume Resistivity – Primary measurement value is display in Ohms/Cm
    •   Ohms Resistance – Primary measurement value is display in Ohm
  • Three available current ranges:
    • 0.5mA to 10mA
    • 10uA to 100uA
    • 1uA to 10uA
  • Includes PC interface software
  • Interfaces with Jandel four point probing units

Universal Probe

Applications

  • 4-Point Probe Measurement of wafer sheet resistance
  • 4-Point Probe Measurement of epitaxial and diffused layer resistivity (where the layer is of the opposite conductivity type to the substrate, or the substrate is an insulator)
  • 3-Point Spreading Resistance Measurement

Principle Features

  • Highly repeatable needle contact conditions owing to controlled velocity of descent
  • Individually adjustable needle loadings with direct indication of set load
  • Kinematic needle guidance system employing precision ruby ball guides and polished tungsten carbide rods
  • Solid tungsten carbide needles with precision radiused tips
  • Accuracy of needle spacing +/- 0.01mm, no side play
  • Needles may be readily replaced without fear of derangement or loss of accuracy
  • Fully visible contact area
  • Micrometer controlled slice displacement for determination of resistivity gradient or junctions on a beveled slice.
  • Hinged steel cover to eliminate effects of light and electrical interference during measurement

General Construction

The probe guidance system is kinematic and thus free of all lateral play. The needles are positioned by upper and lower jeweled guides, each needle being constrained by a spring-loaded ruby ball at each guide. The needles slide through their guides with minimum friction, and exchanging new needles for old or broken ones is a simple, quick operation. Changing needles does not affect the characteristics of the unit – provided that replacement needles are the same diameter – spacing and co-linearity will be retained. Variation in needle diameter do not introduce play.

Velocity Control

This device controls the velocity of the needle descent and the rate of applying load and thus offers uniform contact conditions from one measurement to the next. An air dashpot has been employed, since it’s mechanism is vibration free and has a continuous motion. A spring is applied to the raising and lowering lever, tending to lower the needles. The dashpot is attached to the lever so that the lever is retarded by the piston.

Method of Operation

A cam shaft operated by a small lever projecting through the perspex cover sets the machine for either four probe operation (lever up) or three probe operation (lever down).

i) During four probe operation all four needles rise and fall normally. The velocity control should be set as desired.

ii) During three probe operation for spreading resistance measurements, the tension on the first probe should be reduced to zero and the lever pulled down. This lifts the first probe tension gauge finger so that it is inoperative. the central probe finger is raised slightly so that this probe contacts the specimen last. The velocity control knob should be set to give a probe descent rate of approximately 1mm per second.

The Universal Probe uses four user-replaceable probe tips that are mounted in the Guidance Unit. The Guidance Unit determines the probe tip spacing of either 1.0mm, 1.27mm, or 1.59mm. The individual tips can be user replaced or the entire Guidance Unit (which includes four tips) can be user replaced.

A complete four point probing system consists of the Universal Probe shown above, combined with the ResTest Test Unit.

The Universal Probe is sometimes used to make the three point spreading resistance measurement. Click here for more information.

SPECIFICATION – PROBE NEEDLES
Material: 0.5mm diameter tungsten carbide, 26mm long, 45 degree included angle, 25 micron tip radius (or larger up to 100 microns)
Spacings: 1.00mm, 1.27mm, 1.59mm – tolerance +/- 0.01mm
Travel: 4mm
Insulation resistance: 2 x 105 megOhms at 500 volts
Load: 0-100 grams applied by adjustable individual tension gauges
Specimen: Slice only, 76mm diameter is normal maximum
Mounting table: Ball bearing co-ordinate table with 0-25mm x 0.01mm micrometer screws (others available to order) carries a rotary table with 76mm diameter vacuum slice adaptor 14mm high
Packed for shipment: 480mm x 320mm x 320mm high
Net weight: 7 Kg
Gross weight: 9 Kg

 
ResTest Four Point Probe Measurement Unit

ResTest Four Point Probe Measurement Unit

The ResTest is a combined constant current source and digital voltmeter, which has been designed specifically for use with a four point probe to produce resistivity and sheet resistance measurements. The unit supplies a constant current and can display resultant voltage sheet resistance and volume resistivity.

The ResTest has a large color display and it can read-out in either sheet resistance in the range from 10 milliohms-per-square up to 106 (1 million) ohms-per-square. The range is not as great as the RM3000, however, it is faster and has a larger color display.


 

Downloads

Instruction manual for the Universal Probe (736K PDF file) Instruction manual for the Universal Probe (736K PDF file)
Jandel Universal Probe Guidance Unit, PDF document Jandel Universal Probe Guidance Unit, PDF document (188K PDF file)
Information regarding the constructions and specifications of the Jandel Cylindrical Probe ResTest User Instruction Manual
ResTest Product Brochure

 


 

We Recommend

Universal Probe combined with RM3000 Test Unit features high accuracy, an excellent range, and many features which simplify the four point probing measurement: Universal Probe combined with RM3000 Test Unit


Four-Point-Probes is a division of Bridge Technology. To request further information please call Bridge Technology at (480) 988-2256 or send e-mail to Larry Bridge at: sales@bridgetec.com