Rapid Silicon Dioxide Film Formation on Clean Silicon Surfaces

摘要

Future generations of silicon-based microelectronic circuits will require ever-smaller devices, new classes of devices, and demands for higher reliability, thereby requiring further refinements of silicon planar technology. An understanding of the kinetics of film formation and optical properties of ultrathin silicon dioxide films on a parent silicon substrate is necessary to measure and predict the behavior of such devices. A high-speed ellipsometer and growth chamber were constructed to measure the growth rate of SiO2 on hot silicon substrates from which the prior native oxide had been removed. Data gathered from temperatures between 800 deg C and 1000 deg C for three substrate orientations (100), (111), and (110) reveal the dependence of the refractive index of SiO2 as a function of oxide thickness. No orientation effects were found. Kinetic measurements reveal two new linear growth regions with activation energies of El = 0.603 eV and Ell = 0.794 eV, respectively. X-ray photoelectron spectroscopy provides chemical evidence of oxygen supersaturation and a coesite-like structure near the oxide-substrate interface. The results will provide baseline data necessary for radiation hardening assessments, data to aid the development of the next generation of ellipsometric thin film standards, and will permit process designers to develop thinner device oxides. The instrumentation developed for this work may have commercial applicability for process control feedback and in situ quality assurance.