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Contactless Junction Depth Measurement

IP.com Disclosure Number: IPCOM000073396D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Dupnock, A: AUTHOR [+3]

Abstract

Optical measurement of junction depth is provided for devices in the range of 0.5 microns to 5.5 microns, the normal range of diffusion. Infrared light is directed to a semiconductor member 10 at a fixed angle. A graph 1 is plotted of T(%) percentage transmittance relative to wavelength, where transmittance is defined as the infrared intensity through the wafer I(T) divided by the infrared intensity directed to the wafer I(O). The percentage reflectivity of the incident infrared light R is plotted as a function of wavelength as graph 2 to find that wavelength lambda (min.) which provides the minimum reflectance from the wafer. The minimum reflectivity wavelength is entered on the T(%) transmission curve 1 to find that value of transmittance for the minimum wavelength. A calibration curve 3 of T Min. vs.

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Contactless Junction Depth Measurement

Optical measurement of junction depth is provided for devices in the range of
0.5 microns to 5.5 microns, the normal range of diffusion. Infrared light is directed to a semiconductor member 10 at a fixed angle. A graph 1 is plotted of T(%) percentage transmittance relative to wavelength, where transmittance is defined as the infrared intensity through the wafer I(T) divided by the infrared intensity directed to the wafer I(O). The percentage reflectivity of the incident infrared light R is plotted as a function of wavelength as graph 2 to find that wavelength lambda (min.) which provides the minimum reflectance from the wafer. The minimum reflectivity wavelength is entered on the T(%) transmission curve 1 to find that value of transmittance for the minimum wavelength. A calibration curve 3 of T Min. vs. X(j1) junction depth is prepared and the transmittance T for the minimum wavelength is used to enter the curve to find the junction depth. The calibration curve is different for each impurity but is independent of the profile of the junction to within experimental error.

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