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Measuring the Thickness of SiO(2) and Si(3)N(4) Layers Deposited on Si Substrates

IP.com Disclosure Number: IPCOM000088465D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Hoffmeister, WW: AUTHOR [+2]

Abstract

When X-raying Si substrates, the fluorescence intensity of the SiK line is largely independent of the quality of the substrate surface. This effect allows the measurement of the thickness of insulating films covering the substrate.

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Measuring the Thickness of SiO(2) and Si(3)N(4) Layers Deposited on Si Substrates

When X-raying Si substrates, the fluorescence intensity of the SiK line is largely independent of the quality of the substrate surface. This effect allows the measurement of the thickness of insulating films covering the substrate.

The reduction of the SiK line intensity by thin SiO(2) and Si(3)N(4) layers of the order of 800 - 4000 Angstrom deposited on such substrates can be detected with high precision. It has been found that for a given layer this reduction is a single value function of its thickness. Thus, the thickness of an SiO(2) or Si(3)N(4) layer deposited on an Si wafer is determined by irradiating the probe by an X-ray source with a chromium anode, using an excitation voltage of 20 kv and a tube current of 6 ma. Measuring can be effected, for example, by counting the photons leaving the layer by means of an X-ray spectrometer and an analyzer crystal of pentaerythrite during a time interval of 4 seconds.

The thickness of an SiO(2) layer is a function of the SiK photons detected during a 4-second interval, as shown below. 0 Angstrom 43 634 810 Angstrom 43 043 820 Angstrom 42 876 980 Angstrom 42 795 1430 Angstrom 42 467 1720 Angstrom 42 326 1870 Angstrom 42 158 1960 Angstrom 42 118.

To avoid errors as a result of X-ray reflexes, the probe is rotated during the measurements.

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