Embedded Mechanical Stress Sensors for Advanced Process Control

For state of the art microelectronic technologies, reliability is a major challenge. Mechanical stress induced by the process steps is often at the origin of yield losses. Degradations of electronic devices are usually correlated to the presence of defects such as dislocations, cracks or delaminations. Usual methods for mechanical stress measurement generally require off-line measurements and are not compatible with fast correction of process parameters. We propose here embedded stress microsensors to allow fast monitoring of mechanical stress and enable real time correction of the process parameters. The test vehicle presented here is dedicated to polysilicon stress monitoring. Its feasibility, sensitivity and relevance in an advanced process control objective are particularly investigated.