Mitigating residual stress in Cu metallization

Abstract

The application of a cryogenic thermal excursion to passivated copper films has been demonstrated to dramatically reduce the magnitude of residual stress and to induce compressive, in-plane stress at room temperature. In-situ x-ray diffraction measurements reveal the evolution of in-plane stress within SiC xNyHz and TaN capped Cu films, which undergo significant plastic behavior on cooling and as the film approaches room temperature during heating. The resulting compressive stress represents a more favorable condition to mitigate voiding within the metallization. In-situ and ex-situ measurements of SiCxNyHz capped Cu films reveal that the final stress state is independent of cooling rate. © 2012 American Institute of Physics.