Polychromatic X-Ray Scattering Instrumentation for Real-Time Comparison of Semiconductor Substrate Surface Quality

This program addresses the need for rapid, non destructive, in line semiconduct surface quality analysis accomplished by comparisons with high yielding wafers thereb identifying substrates worthy of further processing investment. This instrumental development goal will be achieved by identifying X ray diffraction, specular and diffuse scattering patterns simultaneously resulting from polycrystalline grain size, epitaxial orientation and surface roughness at the nanoscale. Modified diffractomete hardware will identify scattered intensity vs. forward scattering solid angle simultaneously with arrays of closely spaced solid state detectors for fixed incident angle polychromatic illumination. Initial comparison of X ray diffraction and scattering patterns with both respective Bragg and Maxwell's equations and microscopi surface examination will result in parameters including average grain size, degree o! crystal misorientation and fractal surface roughness Hausdorff dimension for subsequr neural network analysis in real time. Preferred robust hardware components and neurc net architecture will be developed for silicon wafers and subsequently verified with gallium arsenide substrates. Experimental development will include modification of diffractometer goniometer, identification of low incident angle illumination with mon and polychromatic X rays, replacement of proportional counter detector with charge coupled devices or photodiode arrays located in both vertical and azimuthal angles an X ray target composition resulting in a defined and verified polychromatic spectrum.