By: Joaquin GabrielsNovember 24th, 2008

Overview of CMOS CMOS Fabrication Process Overview CMOS Fabrication Process Problems with Current CMOS Fabrication Future Changes in CMOS Fabrication

Complementary metal–oxide–semiconductor (CMOS) Has many different uses:

Integrated Circuits Data converters Integrated transceivers Image sensors Logic circuits

http://en.wikipedia.org/wiki/CMOS

NAND Circuit

http://lsmwww.epfl.ch/Education/former/2002-2003/VLSIDesign/ch02/ch02.html

1. Create a pattern.2. Oxidize small layer,

about 1µm thick.3. Place photoresist on

top of SiO2

4. Place mask(pattern) above photoresist and expose it to UV light.

1. Etch away SiO2 using HF acid or plasma.

2. Remove remaining photoresist with acids.

To create a n well: Diffusion

Heat wafer in Arsenic gas chamber until diffusion occurs. Ion Implantation

Arsenic or phosphorous are implanted in window.

n well

SiO2

A thin layer of oxide is deposited.

A thin layer of polysilicon is deposited using Chemical Vapor Deposition (CVD) .

p substraten well

http://en.wikipedia.org/wiki/Chemical_vapor_deposition

Remove oxide layer using acid.

Dope open area using Ion implantation or diffusion.

p substraten well

n+n+ n+p+p+p+

p substrate

Metal

Thick field oxide

n well

n+n+ n+p+p+p+

Optical lithography is limited by the light frequency.

Material limitations Yield limitations Space limitations

Material changes like using high-k materials.

Design changes SOI(Silicon On Insulator) Double Gate (Finfet) Twin-Tub Process

http://www.fujitsu.com/downloads/MAG/vol39-1/paper02.pdf

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/2002-2003/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%20Part2%2003-20-2002.doc