Durability of Mechanical Damage Gettering Effect in Si Wafers

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Abstract
This paper reports an investigation of the durability of the mechanical damage gettering effect in Si wafers through a 3-step thermal treatment consisting of an 8-hour annealing step between two oxidation steps. The gettering durability in Si wafers with scribe damage on the back surface and with straight dislocations introduced in the neutral plane was examined in relation to the macroscopic strain field, which appears as wafer warpage, and the microscopic strain field, which is present in the vicinity of damage, even after the macroscopic strain was reduced by thermal treatment. When the scribe damage was deep, good durability was obtained, and there was no difference between the gettering effects during the first and second oxidation steps. The macroscopic strain gradient had little effect in promoting gettering. The extent of the gettered range was found to be dominated mainly by microscopic strain and to depend upon the morphology of dislocations.