EFFECTS OF LINEWIDTH, MICROSTRUCTURE, AND GRAIN-GROWTH ON VOIDING IN PASSIVATED COPPER LINES

Tantalum encapsulated copper lines, 0.5-2.0 μm wide, were passivated and heat treated to determine the effect of stress state, microstructure, and grain growth on stress-induced voiding. Void frequency and location were studied as a function of linewidth and heat treatment. Higher stress, narrow lines voided less than lower stress, wider lines. Voiding was also strongly dependent upon thermal treatment before and after passivation. These results are explained by defining preferred sites for void formation and by considering the release of free volume during grain growth in passivated lines.© 1995 American Institute of Physics.