Analytical Feasibility of Laser Induced Stress Wave Thermometry Applied to Silicon Wafers

A model correlating the group velocity of guided plate waves to temperature in anisotropic silicon substrate is presented. The model is developed through numerical solution and manipulation of the dispersion relations while elastic constants are treated as functions of temperature. Results demonstrate that adequate thermal resolution is provided by both the lowest order antisymmetric and symmetric dispersive Lamb wave modes to serve as an effective diagnostic in a non contact thermometry scheme in rapid thermal processing (RTP) of silicon wafers.