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Determining Ion Implantation Profile

IP.com Disclosure Number: IPCOM000090841D
Original Publication Date: 1969-Jul-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Crowder, BL: AUTHOR

Abstract

In order to obtain a measure of the profile of electrically active species produced by ion implantation of impurities in a semiconductor, a test wafer is first prepared. The total concentration of the ion implanted species is varied in one direction ever the surface of the test wafer. The impurity or ion implanted species is of opposite conductivity type to the test wafer. The variation in total concentration is achieved, as in A, using a mechanical shutter which is moved to intercept the uniform ion beam so that different positions of the wafer are exposed for different times. After the wafer is thus prepared, standard junction delineation techniques are employed to determine the impurity profile. One such profile is shown in B with the impurity dosage normalized at the inflection point for junction appearance.

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Determining Ion Implantation Profile

In order to obtain a measure of the profile of electrically active species produced by ion implantation of impurities in a semiconductor, a test wafer is first prepared. The total concentration of the ion implanted species is varied in one direction ever the surface of the test wafer. The impurity or ion implanted species is of opposite conductivity type to the test wafer.

The variation in total concentration is achieved, as in A, using a mechanical shutter which is moved to intercept the uniform ion beam so that different positions of the wafer are exposed for different times. After the wafer is thus prepared, standard junction delineation techniques are employed to determine the impurity profile. One such profile is shown in B with the impurity dosage normalized at the inflection point for junction appearance. It is at this point or depth that the implanted concentration is greatest. At lower dosages, no PN junction is observed and at higher dosages the impurity spreading is observed. The contrast at the inflection point is not observed as sharply as shown in B, but the existence of nearby regions of sharp contrast allows determination of its range directly.

Variation in profile shape with total dosage can be determined using a number of test wafers with different background doping.

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