Browse Prior Art Database

Contactless E-Beam Measurement of Junction Electrical Properties

IP.com Disclosure Number: IPCOM000049847D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 41K

Publishing Venue

IBM

Related People

Ho, PS: AUTHOR [+2]

Abstract

This article describes a measurement technique which accomplishes contactless measurement of junction electrical characteristics and parameters under normal operating conditions and junction measurement of both forward and reverse bias conditions.

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Contactless E-Beam Measurement of Junction Electrical Properties

This article describes a measurement technique which accomplishes contactless measurement of junction electrical characteristics and parameters under normal operating conditions and junction measurement of both forward and reverse bias conditions.

The figure shows a configuration in which an electron beam source and an electron energy analyzer are employed to measure the electrical properties of a junction formed by an overlayer on a substrate without physical contact to the overlayer. For purposes of discussion we consider the current-voltage (I-V) characteristic of a Schottky contact on n-Si. A primary electron beam of current I(p) is incident on the metal overlayer contact. Backscattered electrons (elastics) and secondary (as well as Auger) electrons (inelastics) are generated from the metal surface into vacuum with a total current I(p). The net current I=I(p)-I(s) flows through both the ohmic back contact and the junction depletion region, whose electrical properties are to be determined. If the metal contact thickness t is large compared to the inelastic electron scattering length (i.e., t>>50 angstroms for incident electron beams <30 kV), no hot electrons from the incident beam reach the junction, and only normal equilibrium currents flow through it; these are measured by the current meter I.

A commercially available electron energy analyzer with resolution <50-100 meV can be employed to measure the voltage level of the metal contact (*); changes in this level can be detected to approximately 10 meV or better. Thus, as I(p) is varied, the current I through the junction changes, and the analyzer can be used to measure the corresponding voltage level change across the junction.

For V(bias)=0 the net junction current I can be forward or reverse, depending on whether I(p) < I(p) or I(p) > I(s). As V(bias) is changed (end the voltage level measurement from the analyzer corrected accordingly), the change in electric field between t...