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Measurement of Diffusion, Epitaxial, Profiles and Junction Depths

IP.com Disclosure Number: IPCOM000092049D
Original Publication Date: 1968-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Gardner, EE: AUTHOR [+2]

Abstract

The measurement of the diffusion profile and junction depth of an impurity in a semiconductor wafer can be measured by utilization of photovoltaic effects. A small spot of light, for example, 2 microns in diameter, is incident at 90 degrees on a shallow angle bevel on a diffused epitaxial layer of a semiconductor device. The bevel ratio is, for example, at a 100 to 1 ratio. The photovoltage induced by the light can be measured and is a function of the position of the spot along the bevel relative to the junction, the diffusion length, the concentration of impurities and the condition of the surface if the wavelength is short enough so that it does not penetrate far into the material.

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Measurement of Diffusion, Epitaxial, Profiles and Junction Depths

The measurement of the diffusion profile and junction depth of an impurity in a semiconductor wafer can be measured by utilization of photovoltaic effects. A small spot of light, for example, 2 microns in diameter, is incident at 90 degrees on a shallow angle bevel on a diffused epitaxial layer of a semiconductor device. The bevel ratio is, for example, at a 100 to 1 ratio. The photovoltage induced by the light can be measured and is a function of the position of the spot along the bevel relative to the junction, the diffusion length, the concentration of impurities and the condition of the surface if the wavelength is short enough so that it does not penetrate far into the material. If the light spot is scanned along the bevel and a plot is made of the photovoltage as a function of light spot position, the location of the junction is ascertained by an appreciable voltage difference at the junction. The shape of this plot is a measure of the impurity profile. The position of the surface intersection with the bevel can be determined by placing a sensor at the reflectance angle of the incident light with the surface, thus allowing detection when scanning is completed along the bevel.

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