Apparatus and method for detecting spot defects in integrated circuits

Abstract

Spot defects are detected utilizing an apparatus which comprises a meander structure formed in a high resistivity material on a substrate. The meandor includes intermediate segments, the ends of which are interconnected by folded segments such that an electrical circuit having electrical resistance R is formed between the ends of the meander. A strip of high electrical conductivity material is formed in substantial alignment with and is electrically insulated from a corresponding one of each of the intermediate segments. Each end of each strip is electrically connected to a corresponding end of a corresponding intermediate segment. Defects are identified by measuring the resistance R, between the ends of the meander. This measured value is then compared to the calculated value of R. If the value of the measured resistance is substantially smaller than the calculated value, a flaw due to a spot of additional high conductivity material, is considered to be present. If the measured resistance is substantially greater than the calculated resistance, a flaw due to a spot of missing high conductivity material is determined to exist. The size of the defects, either additional or missing material, can be determined by additionally measuring the resistance of a path comprising two intermediate segments and a foled segment connected therebetween, then calculating the defect size using predetermined formulae.