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A “hybrid” post Cu CMP cleaning process that combines acidic and basic clean in sequence is developed and implemented. The new process demonstrates the strengths of both acidic and basic cleans and achieves a more than 60% reduction in CMP defects, such as polish residues, foreign materials, slurry abrasives, scratches, and hollow metal, relative to an all-basic clean process. It also eliminates the circular ring defects that occur intermittently during roller brush cleans. TXRF scans confirm the reduction of AlOx defects when using the hybrid clean process. XPS spectra show similar Cu surface oxidation states between the basic and hybrid clean processes. As revealed by XRD analysis, surface Cu oxide is dissolved into aqueous solution by the acidic clean chemical. The formation mechanism of circular ring defects and the key to their elimination is discussed. [ABSTRACT FROM AUTHOR]

A test structure specifically designed to allow inline detection of missing spacer is introduced. Missing spacer is too small to be physically detected with any current inspection tool and therefore its existence must be flagged using voltage contrast for detection with an e-beam inspection system. The structure and methodology used to address this defect during the ramp of a recent technology is described. Key benefits include a dramatically faster learning cycle and much better signal-to-noise ratio for split experiment evaluation. Missing spacer is one example of a growing class of nonvisual defects which will greatly impact future semi-conductor technologies. General principles for designing test structures to detect these defect types are discussed. [ABSTRACT FROM AUTHOR]