In-Situ Analysis of Deformation and Mechanical Stress of Packaged Silicon Dies With an Array of Hall Plates

A technique is presented that allows to simultaneously measure stress and deformation of packaged silicon dies. Required is a test chip with an array of Hall plates assembled in a package made of nonmagnetic materials. Exploiting the highly anisotropic magnetic sensitivity of the integrated Hall plates in an external magnetic field, makes it possible to measure the deformation. Moreover, the piezoresistive and piezo-Hall effect allow for measurements of several stress components without extra sensor elements. An optical measurement verifies the new technique, and a standard plastic package is exemplarily analyzed at different temperatures, under the influence of an external force, and at moisture load. The combined knowledge of stress and deformation allows for deeper insight into the mechanical impact of packaging on integrated circuits.