Topical Areas of Research
Physics of Confined Structures
Optical measurements provide an excellent means of characterizing quantum confinement and its impact on the optical response of 1D, 2D, and 3D confined structures. Low temperature photoluminescence provides an excellent means of measuring the exciton binding energy, observing electron – hole liquids, and characterizing carrier lifetime.
All areas of silicon semiconductor characterization and metrology are challenged by the research, development, and manufacturing needs associated with new materials and processes. One focus area is in the characterization and in-line metrology of high k / metal gate film stacks. By combining materials characterization methods including X-Ray Photoelectron Spectroscopy (lab and synchrotron based), Ion Backscattering, X-Ray Diffraction and X-Ray Reflectivity with in line methods such as ellipsometry, we have advanced optical models for the high k dielectrics and the thin metal gate films. Correlation with C-V is always a priority.
We also work in the area of on chip interconnect films and in 3D Through Silicon Via (TSV) metrology. Again, we use the approach of understanding the materials properties through a combined characterization and then develop the appropriate in-line measurement methods. Scanning Acoustic Microscopy provides useful views of the interface between bonded wafers. IR microscopy is well suited to measuring overlay registration. X-Ray microscopy is an excellent means of characterizing voids in the copper TSV structures.
The band gap, dielectric function, and conversion efficiency of photovoltaic materials is a function of the elemental composition, grain structure, and process conditions. Ellipsometry not only measures film thickness, it can fingerprint changes in elemental composition and characterize changes in band gap. Time resolved photoluminescence characterized carrier lifetime which has been correlated to solar conversion efficiency.