  The kSA Multi-beam Optical Sensor (MOS) is a thin film stress, wafer curvature, and thickness measurement tool with integrated real-time feedback for process control. This system is highly sensitive, in-situ or ex-situ, laser based, and extremely robust. kSA MOS measures thin film stress by monitoring substrate curvature with an array of parallel laser beams and a CCD area detector. Optimized optics and detection system combined with proven fitting algorithms result in typical radius of curvature detection of 4 to 10 kilometers, depending on system geometry. Since the technique is optically based, it is compatible with CVD, sputtering, and MBE environments provided that optical access is available to the substrate.
The kSA MOS system was developed jointly by k-Space Associates and Sandia National Laboratory to directly measure thin film stress, curvature, and thickness in real-time during fabrication. Understanding and controlling stress in thin films is critical for achieving desired optical, electronic, and mechanical properties. Many high performance devices rely on "built-in" stress within the individual layers for tailoring specific characteristics. Controlling the degree of stress poses a significant challenge. Unwanted changes in stress can be introduced at any stage of the fabrication process and may lead to degradation in device performance, failure of interconnects and delamination of films. The kSA MOS, Multi-beam Optical Sensor, is ideally suited for real-time feedback to process control systems in the production or research environment to make thin film stress and substrate curvature work for you, not against you. |
