Date of Award
Doctor of Philosophy in Applied Physics - (Ph.D.)
Federated Physics Department
N. M. Ravindra
John Charles Hensel
Bhushan L. Sopori
Earl David Shaw
John Francis Federici
The objective of this dissertation is to investigate the major issues concerning applications of pyrometry for applications in rapid thermal processing (RTP) of silicon related materials. The research highlights of this work are:
Establishment of spectral ernissometry as a novel, reliable and reproducible technique for:
Determination of wavelength and temperature dependent reflectivity, transmissivity, emissivity and temperature, simultaneously, of silicon related materials and structures. The emissometer operates in the wavelength range of 1-20mm and temperature range of 300-1200K. The analysis of the influence of morphological effects on the radiative properties by measurement of (a) front-smooth incidence versus backside-rough incidence of singleside polished silicon wafers and (b) single versus double-side polished wafers. This is the first time in the literature that such a study is devoted to detect differences in the optical properties of the same sample. Attempts have been made to verify the VandenabeeleMaex one-parameter model against the experimentally obtained optical properties for rough surfaces. The model has been proven to be inaccurate and inadequate for simulating the measured properties.
Establishment of methodologies and schemes for deconvolution of the measured optical properties to yield the fundamental constants such as absorption coefficient a. Effects of wavelength, temperature, the total available free carriers both by doping and thermal generation and doping types have been considered in the deconvolution process. Comparisons have been sought with the available knowledge of cc in the literature by the extensive use of the Multi-Rad model. This is a state of the art model that has been developed by MIT/SEMATECH.
The first detailed investigation of the radiative properties of SIM0X has been performed.
The first detailed experimental measurements of the radiative properties Of Si3N4 have been performed. The real part of the dielectric constant or refractive index has been deconvoluted from the measured properties in the near-rnid IR.
A thorough testing of the models and simulation tools available to the industry has been made. The models have been utilized extensively in investigating the optical properties, and the effects of surface morphology. The models utilized in performing the simulations of the optical properties of ideally double-side polishes wafers agree in their basic mathematical approaches, i.e. the Abele's matrix theory and differ in the degree of complexity and number of parameters involved. The models utilized to achieve the surface effects task fall under two categories: simple approach that utilizes an extension of the equations that treat the parallel plane properties by relating the roughness effect linearly with the ideally polished plane surfaces, and the other proposed by NREL that utilizes a complex solid-state approach for the optical parameters and a statistical (e.g. MonteCarlo) technique that tends to average the behavior of a photon incident on the textured surface over all the possible angles and wavelengths.
Various approaches using wafer emissivity independent tools for non-contact temperature measurements are discussed with emphasis on the advantages and limitations of the technique.
Abedrabbo, Sufian, "Emissivity measurements and modeling of silicon related materials and structures" (1998). Dissertations. 936.