Signatone
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The Signatone Pro4 is a four-point-probe resistivity system. The Signatone Pro4 is designed to measure resistivity and sheet resistivity of wafers and other materials. The Signatone Pro4 has a standard range of 10µΩ to 100MΩ per square when used with a Keithley 2450 series source meter.[1][2]
Plate 01Lucas Labs Pro4-4000 4 Point Probe #60377
The Signatone Pro4 is a resistivity measurement system for measuring resistivity and sheet resistivity of wafers and other materials. The Signatone Pro4 series provides sheet and bulk resistivity measurements. The system includes a test stand with a probe head, a test meter, software, and a notebook computer.[1][5][3][4]
The Pro4 makes measurements by lowering the four point probe head onto the sample and then starting the test in software. The computer automatically controls a Keithley source meter and steps through a number of current settings to find a suitable current for accurate readings. The system then takes and records a voltage to current measurement. The system uses the Dual Configuration test method of ASTM Standard F84-99 to compensate for errors in probe spacing and errors caused by proximity to the edge of the conducting layer.[2]
The Pro4 software manages tests, displays results, and allows printout or export of data. The user enters the sample size and shape, edge exclusion, and number of test points. The software can run an Auto Test across all configured points, run a Single Test at one point, or Retest Point after an automatic run. The software displays a graphic of target probe points and prompts the user to move to the next position. After an automatic test sequence, the software displays the average value and can report average, standard deviation, minimum, and maximum.[2][5]
A resistivity measurement system is typically used after a conductive or semiconductive layer has been formed and before later process decisions depend on electrical uniformity or target resistance. A tool of this class fits into characterization and process control work around film formation, annealing, implant activation, and similar module development steps.
The Signatone Pro4 is used for sheet resistance measurement of thin films. The Signatone Pro4 is used for resistivity and sheet resistivity measurements on wafers and other materials. The standard range of the system is 10µΩ to 100MΩ per square when used with the Keithley 2450 series source meter.[6][1][5][2]
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The user lowers the four point probe head onto the sample and starts the test in software. The computer automatically controls the Keithley source meter, steps through current settings to find an ideal current, and records a voltage to current measurement.[2]
The following facts about the Pro4 are absent from this record as of this revision. First-hand knowledge or a citation closes a gap; every submission is reviewed before publication.
No publicly documented production dates or lifecycle milestones (introduction, end of production, EOL) for the Pro4 are on record.
Answerable by: OEM historical records or a trade-press announcement
No publicly documented variants, configuration options, or revision breakpoints of the Pro4 are on record.
Answerable by: an OEM product catalog or an engineer who ordered or specified the tool
The control-system platform and OS era of the Pro4 are not on record.
Answerable by: an engineer who operated it or OEM installation records
No publicly documented failure modes or field errata for the Pro4 are on record.
Answerable by: a field service engineer, process engineer, or maintenance technician
The process node or technology generation of the Pro4 is not on record.
Answerable by: an OEM datasheet or a fab qualification report
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Last updated Oct 17, 2026.