1. Fabrication Laboratory
Spring 2012

2. References
Handout
J.D. Plummer, M.D. Deal, and P.B. Griffin, Silicon VLSI Technology: Fundamentals, Practice and Modeling, Prentice-Hall, 1st Ed., 2001.
H. Xiao, Introduction to Semiconductor Manufacturing Technology, Prentice Hall, 1st Ed., 2001.
S.K. Ghandhi, VLSI Fabrication Principles: Silicon and Gallium Arsenide, John Wiley & Sons, 2nd Ed., 1994.
P. van Zant, Microchip Fabrication, McGraw-Hill, 4th Ed., 2000.
S.M. Sze, VLSI Fabrication, McGraw-Hill, 2nd Ed., 1988.
Y. Tsividis, Operation and Modeling of The MOS Transistor, Oxford University Press, 2nd Ed., 1999.

3. Grading
40% final exam
40% experimental expertise
20% project

4. Introduction to Device Fabrication
Farshid Karbassian

5. Outline Historical Overview Wafer Manufacturing Cleanroom Technology
Fabrication Process
Thermal Oxidation
Deposition
Photolithography
Etching

6. 6

7. Historical Overview
First Transistor
Bell Laboratory-1947

8. Nobel Prize in Physics (1956)
Historical Overview
Nobel Prize in Physics (1956)
“for their research on semiconductors and their discovery of the transistor effect”

9. Invention of Integrated Circuits
Historical Overview
Invention of Integrated Circuits
Texas Instruments-1958
Fairchild-1959

10. Nobel Prize in Physics (2000)
Historical Overview
Nobel Prize in Physics (2000)
“For basic work on information and communication technology”
“for developing semiconductor heterostructures used in
high-speed and optoelectronics”
“for his part in the invention of
the integrated circuit”

11. Today's Integrated Circuits
Historical Overview
Today's Integrated Circuits

12. Moore’s Law The number of transistors on a chip
Historical Overview
Moore’s Law
The number of transistors on a chip
doubles roughly every two years.

13. Historical Overview
Scaling

14. New Structures Tri-gate Transistor FinFET CNTFET Historical Overview
V. Iyengar, et al. IEEE Trans. Electron Devices (2007)
Tri-gate Transistor
FinFET
CNTFET
A. Javey, et al. Nature (2003)
H. Sellier, et al. Phys. Rev. Lett (2006)

15. Wafer Manufacturing

16. Why Silicon? About 25.7% of the earth’s crust is silicon.
Wafer Manufacturing
Why Silicon?
About 25.7% of the earth’s crust is silicon.
Si raw material can be found anywhere in large quantities.
Crystallization of Si is much cheaper than any other semiconductor material.
SiO2

17. Wafer Manufacturing
Crystal Pulling
Czochralski Crystal Growth

18. Wafer Manufacturing
Slicing

19. Lapping, Etching and Polishing
Wafer Manufacturing
Lapping, Etching and Polishing
To remove damages caused by slicing several steps are performed so that wafers with one mirror finish will obtain.

20. Cleanrooms,Wafer cleaning & Gettering
Modern IC factories employ a three tiered approach to control unwanted impurities:
Clean factories
Wafer cleaning
Gettering

21. Cleanrooms Fab process is done in an environment called cleanroom.
A cleanroom is
identified by a class
number which shows
how clean it is.

22. RCA cleaning RCA I NH4OH:H2O2:H2O 1:1:5 – 1:2:7 (70-80OC) DI water
RCA II
HCl:H2O2:H2O 1:1:6 – 1:2:8 (70-80OC)

23. Thermal Oxidation
At high temperature O2 molecules diffuse across an existing oxide layer to reach the Si/SiO2 interface.
Oxidation is also used for device isolation.

24. Deposition
Deposition is a necessary step in the fabrication technology.
p-type Si substrate
SiO2
gate material (polysilicon)

25. Patterning
p-type Si substrate
SiO2
polysilicon
metal
photoresist

26. Photolithography 1) Vapor prime 2) Spin coat 3) Soft bake 4) Alignment
UV Light
HMDS
Resist 
Mask 
1) Vapor prime
2) Spin coat
3) Soft bake
4) Alignment
and Exposure
6) Develop
8) Develop inspect
5) Post-exposure
bake
7) Hard bake

27. Diffusion

28. Finished chips

29. Dicing Samples are ready to dice now. After dicing, gold wires
are bonded to the chips,
and then they are
packed.

30. Bonding

31. Bonding

32. Packaging
Types of packages:

33. Simulation
Process Simulation
Device Simulation

34. 34

35. Any questions?