Transcript CMOS Fabrication - University of California, Irvine

By: Joaquin Gabriels
November 24th, 2008
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Overview of CMOS
CMOS Fabrication Process Overview
CMOS Fabrication Process
Problems with Current CMOS Fabrication
Future Changes in CMOS Fabrication
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http://en.wikipedia.org/wiki/CMOS
Complementary metal–oxide–semiconductor (CMOS)
Has many different uses:
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Integrated Circuits
Data converters
Integrated transceivers
Image sensors
Logic circuits
NAND Circuit
http://lsmwww.epfl.ch/Education/former/20022003/VLSIDesign/ch02/ch02.html
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4.
Create a pattern.
Oxidize small layer,
about 1µm thick.
Place photoresist on
top of SiO2
Place mask(pattern)
above photoresist and
expose it to UV light.
1.
2.
Etch away SiO2
using HF acid or
plasma.
Remove remaining
photoresist with
acids.
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To create a n well:
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Diffusion
 Heat wafer in Arsenic gas chamber until diffusion occurs.
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Ion Implantation
 Arsenic or phosphorous are implanted in window.
SiO2
n well
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A thin layer of oxide
is deposited.
A thin layer of
polysilicon is
deposited using
Chemical Vapor
Deposition (CVD) .
n well
p substrate
http://en.wikipedia.org/wiki/Chemical_vapor_deposition
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p+
Remove oxide layer
using acid.
Dope open area
using Ion
implantation or
diffusion.
n+
n+
p+
p+
n well
p substrate
n+
Metal
Thick field oxide
p+
n+
n+
p+
p+
n well
p substrate
n+
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Optical lithography is limited by the light
frequency.
Material limitations
Yield limitations
Space limitations
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Material changes like using high-k materials.
Design changes
SOI(Silicon On Insulator)
 Double Gate (Finfet)
 Twin-Tub Process
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http://www.fujitsu.com/downloads/MAG/vol39-1/paper02.pdf
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CMOS Digital Integrated Circuit Design - Analysis and Design by S.M.
Kang and Y. Leblebici
http://www.fujitsu.com/downloads/MAG/vol39-1/paper02.pdf
“Introduction to VLSI Circuits and Systems,” John Wiley and Sons, 2002
http://lsmwww.epfl.ch/Education/former/20022003/VLSIDesign/ch02/ch02.html
http://en.wikipedia.org/wiki/Chemical_vapor_deposition
users.ece.utexas.edu/~adnan/vlsi-05/lec0Fab.ppt
http://en.wikipedia.org/wiki/CMOS
www.usna.edu/EE/ee452/LectureNotes/02_CMOS_Process_Steps/08_Simple_CMOS_Fab.ppt
http://en.wikipedia.org/wiki/Silicon_on_insulator
access.ee.ntu.edu.tw/course/VLSI_design_90second/data/Chapter%203%20Part
2%2003-20-2002.doc