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Resistivity Test System

IP.com Disclosure Number: IPCOM000093192D
Original Publication Date: 1967-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Hallenback, JF: AUTHOR [+3]

Abstract

This circuit permits testing the resistivity of a component. Preferably, the circuit is used to test the resistivity of a semiconductor epitaxial layer. Three probes A, B, and C are used to measure the breakdown voltage of a semiconductor epitaxial layer formed on a substrate or wafer of the same conductivity type as the epitaxial layer, but of lower resistivity.

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Resistivity Test System

This circuit permits testing the resistivity of a component. Preferably, the circuit is used to test the resistivity of a semiconductor epitaxial layer. Three probes A, B, and C are used to measure the breakdown voltage of a semiconductor epitaxial layer formed on a substrate or wafer of the same conductivity type as the epitaxial layer, but of lower resistivity.

Start cycle switch S1 is closed discharging a capacitor located in the Peak Holding Readout circuit. K1 is a latching relay which is energized and its action is mechanically locked. Contacts K1A remove the short from the constant current generator, EMC Current Supply, and also light the cycle-on indicator. Contacts K1B place a holding voltage on the SCR anode. Contacts K1C connect programming ramp, Ramp Generator, to constant current generator. The rate of increase of the output current is approximately 7 ma per second. Contacts K1D unshort the condenser in the integrator of the Ramp Generator allowing it to charge and produce the programming ramp. A linear current ramp is applied to the test sample by way of forward bias probe B. The voltage seen between voltage pickup probe A and reverse bias probe C is applied to an amplifier in the Peak Holding Readout. The output of the amplifier is stored on a condenser isolated by a diode from the input amplifier. The voltage on the condenser is applied to a voltage follower operational amplifier. The latter has a very high input impedance...