Dynamics of moisture interactions with wafer and reactor surfaces during semiconductor processing
AuthorShero, Eric James, 1969-
Engineering, Electronics and Electrical.
Engineering, Materials Science.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractThe outgassing properties of materials utilized in semiconductor manufacturing are of critical importance to understanding homogeneous contamination problems. This dissertation focuses on the interaction of moisture and the oxide surfaces of the silicon wafer and electropolished stainless steel. These are the two most relevant surfaces to the semiconductor industry. EPSS is prevalent in both high purity gas distributions systems and tools, and the silicon wafer is not only involved in every process step, it is the substrate upon which integrated circuits are based. The outgassing of moisture from these surfaces was investigated using both API and EI mass spectrometers. Data was collected at near atmospheric pressures, in inert gas flow systems in both high (>10 ppm) and low (300 ppb) concentration ranges. While EPSS outgassing data was previously available, the outgassing of the oxide film on the Si <100> wafer surface was obtained for the first time under these conditions. Deuterated water studies showed the moisture does dissociatively adsorb on the wafer surface to some extent. A review of previous adsorption/desorption models for moisture on EPSS was presented. Although many kinetic models have been proposed, most are based on empiricism, and therefore lack physical meaning. As a result, many of the models are limited to specific concentration ranges and often give unrealistic surface concentrations outside these bounds. These models were discussed, because many of the principle elements of them could be extended to the outgassing of the silicon wafer surface. In order to correct some of the deficiencies in the modeling of the outgassing of metal/metalloid oxide surfaces, a multilayer adsorption/desorption model was developed. The attempt was to avoid the empiricism of previous models by integrating known chemical and physical interactions for moisture on these oxides into the approach. Furthermore, the multilayer model utilizes a range of energetics that are thought to occur between moisture and these surfaces. The model utilizes an activation energy that varies with the number of intermolecular interactions a water molecule experiences. The kinetic model is consistent with the BET multimolecular model at equilibrium.
Degree ProgramGraduate College
Chemical and Environmental Engineering