Semiconductor Processing and Characterization … Processing and Characterization Techniques:...
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Semiconductor Processing and Characterization Techniques: Diffusion Professor Benjamín Alemán Department of Physics University of Oregon (Gatan, 2003)
Transcript of Semiconductor Processing and Characterization … Processing and Characterization Techniques:...
Semiconductor Processing and Characterization Techniques:
Diffusion
Professor Benjamín AlemánDepartment of PhysicsUniversity of Oregon
(Gatan, 2003)
Planar Processing with Semiconductors (Silicon):Course Map
• Crystal growth (semiconductors)• Wafer doping (in situ)• Wafer characteristics• SiO2 growth*• Defects and impurities
• SiO2 growth*• Lithography• Masked diffusion doping• Vacuum Systems• Thin Films: CVD, MBE,
PVD, ALD• Implantation• Wet and Dry Etching• Integration
Impurity Doping
How do we make the n doped regions of FET?
Metal-Oxide-Semiconductor FET
Masked Impurity doping: controlled 3D localization of dopant
Diffusion
Implantation
p-type
acceptors
n-type
donors
Si Solid solubility (atoms/cm3)vs. Temperature
Diffusion coefficient in Si vs. 1/T
Constant-total-dopant diffusion profiles:Gaussian
𝐶 𝑥, 𝑡 =𝑆
𝜋𝐷𝑡exp −
𝑥2
4𝐷𝑡
Constant-surface-concentration diffusion profiles:Complementary error function (erfc)
𝐶 𝑥, 𝑡 = 𝐶𝑠 erfc(𝑥
2 𝐷𝑡)
Electron energy loss spectroscopy (EELS)
(Gatan, 2003)
(Suenaga, 2010)
(Gatan, 2003)
Concentration-dependent diffusion profilesbecome box-like with increasing 𝛾
Boron, Arsenic
Gold, platinum;avoided in CMOS
Dopants diffuse laterally an a mask edge
Dopant profiles change during SiO2 growth because dopants can diffuse into SiO2
SiO2 accepts
SiO2 rejects
