Method for chemical surface passivation for in-situ bulk lifetim

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427299, H01L 21302

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active

055808280

ABSTRACT:
Minority carrier bulk lifetime maps are accomplished using in-situ .mu.-PCD measurement techniques on a non-oxidized Si specimen of either polarity. Surface passivation of the specimen is accomplished chemically, preferably using a solution of iodine in ethanol with a concentration in the range of about 0.02 mol.multidot.dm.sup.-3 to about 0.2 mol.multidot.dm.sup.-3. For n-type specimens, a solution of concentrated alkaline such as ammonia, sodium- and potassium-hydroxide is especially effective. For either type specimens, a solution of HF at about 40% m/m is also effective. Surface passivation according to the present invention reduces surface recombination velocities to 10 cm/second or less. The specimen to be measured is placed in a container of passivation solution such that the specimen surfaces are covered with a solution film of about 1 mm or less. The container preferably is transparent to microwave and laser optical energy, and passivation and measurement can occur simultaneously. A method and apparatus are disclosed.

REFERENCES:
patent: 3684592 (1972-08-01), Chang et al.
patent: 4973563 (1990-11-01), Prigge et al.
Article entitled "Unusually Low Surface-Recombination Velocity on Silicon and Germanium Surfaces" by Yablonovitch, D. L. Allara, C. C. Chang, T. Gmitter, T. B. Bright, pub. in Jul. 14, 1986 issue of Physical Review Letters, Vo. 57, No. 2.
Article entitled "The Passivation of Electrically Active Sites on the Surface of Crystalline Silicon by Fluorination", by B. R. Weinberger, H. W. Deckman, E. Yablonovitch, Gmitter, W. Kobasz, S. Garoff, pub. J.Vac.Sci.Technol, A3(3), May/Jun. 1985.
Article entitled "A Chemical/Microwave Technique for the Measurement of Bulk Minority Carrier Lifetime in Silicon Wafers", by Keung L. Luke and Li-Jem Cheng. J. Electrochem. Soc. Solid State Sci And Tech, Apr. 1988, pp. 957-961.

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