ASTM F1391-93(2000)

This standard was transferred to SEMI (www.semi.org) May 2003

1.1 This referee test method covers the determination of substitutional carbon concentration in single crystal silicon. Because carbon may also reside in interstitial lattice positions, when in concentrations near the solid solubility limit, the results of this test method may not be a measure of the total carbon concentration.

1.2 The useful range of carbon concentration measurable by this test method is from the maximum amount of substitutional carbon soluble in silicon down to about 0.1 parts per million atomic (ppma), that is, 5 X 10 15 cm -3 for measurements at room temperature, and down to about 0.01 ppma, that is, 0.5 X 10 15 cm -3 at cryogenic temperatures (below 80 K).

1.3 This test method utilizes the relationship between carbon concentration and the absorption coefficient of the infrared absorption band associated with substitutional carbon in silicon. At room temperatures (about 300 K), the absorption band peak is at 605 cm -1 or 16.53 [mu]m. At cryogenic temperatures (below 80 K), the absorption band peak is at 607.5 cm -1 or 16.46 [mu]m.

1.4 This test method is applicable to slices of silicon with resistivity higher than 3 [omega]-cm for -type and higher than 1 [omega]-cm for -type. Slices can be any crystallographic orientation and should be polished on both surfaces.

1.5 This test method is intended to be used with infrared spectrophotometers that are equipped to operate in the region from 2000 to 500 cm -1 (5 to 20 [mu]m).

1.6 This test method provides procedure and calculation sections for the cases where thickness values of test and reference specimens are both closely matched and not closely matched.

1.7 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.