Download - BYU Physics and Astronomy:-杨百翰大学物理与天文学.ppt
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1、5/26/2019,Joseph Choi, Dept. of Physics, Brigham Young University,1,-Honors Thesis Defense- In Situ Ellipsometry of Surfaces in an Ultrahigh Vacuum Thin Film Deposition Chamber,Joseph Choi Department of Physics and Astronomy, Brigham Young University June 19, 2001,5/26/2019,Joseph Choi, Dept. of Phy
2、sics, Brigham Young University,2,Definition of Terms,UHV (ultrahigh vacuum)- Base pressure 10-9 torr. (Atmospheric pressure is 7.6 x 102 torr) Ellipsometry- Optical measurement technique of reflection, transmission, optical constants, and thickness using polarization of light. In situ- Measurement i
3、nside the chamber without opening to the atmosphere. Evaporation- Deposition of material by thermally heating it using metallic boats with high resistance. Sputtering- Deposition by bombarding positive ions onto the material, and physically vaporizing it.,5/26/2019,Joseph Choi, Dept. of Physics, Bri
4、gham Young University,3,Research Goals,Building: Build a UHV (ultrahigh vacuum) chamber with in situ ellipsometry, sputtering, and evaporation capabilities. Measurement / Modeling: Measure and develop model for thin film oxidation.,5/26/2019,Joseph Choi, Dept. of Physics, Brigham Young University,4,
5、Motivation Study of Oxidation,Reflectance of a silicon film can vary from 70% to below 5% dependent on oxidation. Immediate oxidization when exposed to atmosphere.,(Model of a silicon film produced using IMD),5/26/2019,Joseph Choi, Dept. of Physics, Brigham Young University,5,Thesis Description,Desi
6、gn and building of vacuum chamber from stainless steel body made by Varian, Inc. Since April 2000. UHV, ellipsometry, deposition, procedures. Ruthenium thin film ( 290 ) sputtered in HV (high vacuum;10-8-10-6 torr). Real-time in situ ellipsometric measurements to analyze Ru thin film and its oxidati
7、on.,5/26/2019,Joseph Choi, Dept. of Physics, Brigham Young University,6,UHV Vacuum (10-9 torr),Benefit- Purity of film: - Comparison with HV (10-6 torr): Gas flux 1 cm2/sec. Achieving UHV: - Cleanliness: No oil; cleaning agents (hexane, methanol). - Bake out: 250 C to eliminate water, hydrogen, spee
8、d degassing. - Parts: Minimize o-rings, use metal-to-metal seals. - Material: Low outgas rates (Aluminum, stainless steel). - Machining: Inert gas welding or vacuum brazing.,5/26/2019,Joseph Choi, Dept. of Physics, Brigham Young University,7,Conflat flange- Copper seal,Thermocouple,Heating tape- Bak
9、e out,Cleaning agent- Methanol,Bake out power control- Variac + Transformer,5/26/2019,Joseph Choi, Dept. of Physics, Brigham Young University,8,Vacuum Pumps,Principle - Cold trap. - Large surface area. Sorption pumps - Atmosphere to roughing pressure (10-3 torr). Cryopump - To UHV pressure.,5/26/201
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