Thin Films area of wafer fabrication Wafer fabrication(front-end) Wafer start Thin Films Polish Completed wafer Diffusion Photo Etch Test/Sort Implant Used with permission from Advanced Micro Devices ducn复旦大学张荣君
rjzhang@fudan.edu.cn 复旦大学 张荣君 Thin Films Area of Wafer Fabrication Test/Sort Thin Films Implant Diffusion Etch Polish Completed wafer Photo Wafer fabrication (front-end) Unpatterned wafer Wafer start Used with permission from Advanced Micro Devices
Thin Film deposition Layering: Different Methods Growth Thermal Oxidation(SiO,) Spin on Films Spin on Dopants (soD), spin on Glass(SoG) Deposition Chemical Vapor Deposition(CVD APCVD(atmospheric pressure LPCVD (low pressure) PECVD(plasma enhanced) Epitaxial Growth(single-crystal films) Physical Vapor Deposition(PVD) Sputter Evaporation · Electroplating zhang(@fudan.edu.cn复旦大学张荣君
rjzhang@fudan.edu.cn 复旦大学 张荣君 Thin Film Deposition • Layering: Different Methods – Growth • Thermal Oxidation (SiO2) – Spin on Films • Spin on Dopants (SOD), Spin on Glass (SOG) – Deposition • Chemical Vapor Deposition (CVD) – APCVD (atmospheric pressure) – LPCVD (low pressure) – PECVD (plasma enhanced) – Epitaxial Growth (single-crystal films) • Physical Vapor Deposition (PVD) – Sputter – Evaporation • Electroplating
Thin Film Deposition Thin Film Properties: The properties that your process requires will determine which method of deposition must be used Thickness: microns, angstroms Uniformity: variation in thickness Composition (ie. What's in it? Weight · Refractive index Reflectivity Defects :##/cm2 · Particles Hillocks Film Stress: dynes/cm Conformality (or step coverage, or gap fill): determined by SEM cross section zhang@fudan.edu.cn复旦大学张荣君
rjzhang@fudan.edu.cn 复旦大学 张荣君 Thin Film Deposition • Thin Film Properties: The properties that your process requires will determine which method of deposition must be used. – Thickness: microns, angstroms – Uniformity: % variation in thickness – Composition (ie. What’s in it?) • Weight % • Refractive index • Reflectivity – Defects: #/cm2 • Particles • Hillocks – Film Stress: dynes/cm2 – Conformality (or step coverage, or gap fill): determined by SEM cross section
Thin Film Deposition Chemical Vapor Deposition( CVD: Deposition of a solid film on the wafer surface by reaction of chemical gasses Reaction should take place at the wafer's surface otherwise, airborne particles will develop Advantages of CVD: low temperature film deposition(compatible with metal layers) much higher deposition rate than thermal oxides VERY conformal films are possible A fundamental limitation of cvd Because it is a chemical process, suitable source gasses must be obtained to deposit a film using CVD Films usually deposited via CVD silicon dioxide, silicon nitride, tungsten (55) polysilicon zhang@fudan.edu.cn复旦大学张荣君
rjzhang@fudan.edu.cn 复旦大学 张荣君 Thin Film Deposition • Chemical Vapor Deposition (CVD): – Deposition of a solid film on the wafer surface by reaction of chemical gasses. • Reaction should take place at the wafer’s surface, otherwise, airborne particles will develop • Advantages of CVD: – low temperature film deposition (compatible with metal layers) – much higher deposition rate than thermal oxides – VERY conformal films are possible • A fundamental limitation of CVD: – Because it is a chemical process, suitable source gasses must be obtained to deposit a film using CVD. • Films usually deposited via CVD: – silicon dioxide, silicon nitride, tungsten（钨）, polysilicon
Thin Film Deposition A CVD system includes the following a heated chamber(MUCH lower temperature, 350-500C, than oxidation or diffusion. This allows post-metal processing. Vacuum or exhaust (to remove byproduct gasses) Gas delivery system RF power(only for PECVD) zhang@fudan.edu.cn复旦大学张荣君
rjzhang@fudan.edu.cn 复旦大学 张荣君 Thin Film Deposition • A CVD system includes the following: – A heated chamber (MUCH lower temperature, 350-500C, than oxidation or diffusion. This allows post-metal processing.) – Vacuum or exhaust (to remove byproduct gasses) – Gas delivery system – RF power (only for PECVD)