REAL-TIME OPTICAL DIAGNOSTICS FOR EPITAXIAL-GROWTH

Various optical diagnostics are being developed to meet new challenges in epitaxial growth. Layer thicknesses and compositions, the primary parameters needed for growth control, can be obtained with bulk-oriented probes such as reflectometry and ellipsometry. New derivative algorithms for determining near-surface dielectric properties and compositions from kinetic ellipsometric and complex-reflectometric data have made possible closed-loop feedback control of alloy structures, including compositionally graded structures. New information about the kinetics and chemistry of growth is being obtained by surface-oriented probes such as laser light scattering (LLS), surface photoabsorption (SPA), and reflectance-difference (-anisotropy) spectroscopy (RDS/RAS). Examples are provided, and likely directions of further progress discussed.