Screening of metal film defects by current noise measurements

Abstract

Current noise measurements at high current densities have been applied to the detection of constrictions in thin-film metallization. Potentially open metal films due to scratches, notching, improper step coverage, etc., are easily detected. The noise level, in the absence of such defects, appears to be an indicator of potential electromigration failure. For Al films, the minimum current density to obtain sensitivity is 2 × 106 A/cm2. For more refractory metals the minimum is higher (e.g., Mo, 1 × 107 A/cm2).