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# Measuring Thickness and Resistance of Semiconductor Layers

IP.com Disclosure Number: IPCOM000096572D
Original Publication Date: 1963-Jul-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 31K

IBM

Hora, H: AUTHOR

## Abstract

This device measures the thickness and the resistance of semiconductor layer 6. These are supported on a semiconductor substrate 7 of a different conductivity type.

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Measuring Thickness and Resistance of Semiconductor Layers

This device measures the thickness and the resistance of semiconductor layer 6. These are supported on a semiconductor substrate 7 of a different conductivity type.

The device essentially comprises five aligned measuring probes. These are placed upon layer 6 to be measured. Probes 1, 2, 3 and 4 are spaced by a constant distance s1. The fifth measuring probe 5 has a different distance, e. g., s2, from measuring probe 3. By directing a constant current through two outer measuring probes, it is possible to measure the potential difference occurring between two intermediate measuring probes. The quotient of current divided by voltage is a measure for the thickness and the resistivity of layer 6.

The operation is as follows. In a first measuring step, a current is applied, e.
g., through measuring probes 1 and 4 and the voltage between probes 2 and 3 is measured. In a second measuring step, a current is applied, e. g., through measuring probes 1 and 5 and the voltage between probes 2 and 3 is measured. The two measuring steps result in two equations for the two unknown quantities. The thickness and the resistivity of layer 6 may thus be determined. The mathematical procedure for solving the two equations depends on whether substrate 7 has a substantially higher resistivity than that of layer 6 or may be electrically insulated by an additional applied voltage, which would be the simplest case. The procedure als...