NUMERICAL ELLIPSOMETRY - REAL-TIME SOLUTIONS USING MAPPING ONTO THE COMPLEX INDEX PLANE

While in situ ellipsometry measurements can be made on growing films, real-time solutions for thickness and optical properties remain challe nging. Numerical techniques are necessary because for practical materi al systems, the equations are not generally invertible. In the absorbi ng film on a known substrate problem, the typical real number unknowns (film n(1), k(1), and d) outnumber the real parameters (psi and Delta ) obtained in a single measurement. Although it is known that two inte rsecting sets of n(1), k(1), and d values are established from two mea surements, in the past these sets have not been well understood. The w ork here is a thorough investigation of such curves and explores all t heoretically possible intersections for metals depositing onto an oxid e substrate. Mathematical and material considerations identify the sol ution intersection in a few milliseconds for real-time monitoring and control. (C) 1996 American Vacuum Society.