silicon IC fabrican technology

1. Silicon IC- Fabrication
Technology
Tribhuwan Kumar
B.Tech final year 7th Semester
Electronics& Communication
Govt. Engineering
college Bikaner
(Rajasthan)

2. Silicon IC- Fabrication
Technology
To realize Semiconductor DEVICES or an
INTEGRATED CIRCUIT an adequate set of
technological steps is required that allows the
realization of the same on top surface/plane of a
semiconductor wafer.

3. Basic Steps of Si I.C-Fabrication:
1.
2.
3.
4.
5.
Chemical Cleaning of Silicon Wafer
Oxidation
Photolithography
Oxide Etching
Diffusion
Above steps are performed more than once depending on
complexity of the I.C being fabricated. Subsequently, following
steps are performed to accomplish the I.C fabrication.
6. Thin Film Metal Deposition
7. Photolithography
8. Metal etching
9. Annealing
10.Testing

4. P-N Junction Diode
Circuit symbol
Schematic diagram
p-type
net acceptor
concentration NA
n-type
net donor
concentration ND
cross-sectional area AD
ID
+
VD
–

5. Practical P-N Junction Diode Structure
ID
+ ID
metal
SiO2
For simplicity, assume that
the doping profile changes
abruptly at the junction.
VD
SiO2
p-type Si
P-type
n-type Si
–
metal

6. Fabrication of Silicon P-N Junction Diode
1. Chemical cleaning of silicon wafer
2. Oxidation
3. Photolithography
4. Silicon oxide etching
5. Diffusion
6. Thin film Metal (Aluminium) Deposition
7. Photolithography
8. Metal Etching
9. Semiconductor-Metal contact formation

7. Process Flow Chart
for
Fabrication of P-N Junction
Si
n-Silicon
Chemically cleaned silicon wafer
SiO2
Silicon dioxide
Si
n-Silicon
Silicon-Oxide Interface
Silicon Wafer with a Grown Silicon dioxide layer
on top.

8. Silicon dioxide
Positive
Photo Resist Layer
n-Silicon
Spin Coat of Positive Photo Resist
Ultra Violet Rays
Glass plate
Emulsion
Silicon dioxide
Mask
U.V Exposed Region (Polymerized
Photo Resist)
n-Silicon
Photo Resist Polymerization on U.V Exposure

9. Silicon dioxide
Silicon dioxide
n-Silicon
Windows in Photo Resist After Development
Silicon dioxide
Silicon dioxide
n-Silicon
PR Coating on back of the wafer to protect oxide

10. Silicon dioxide
n-Silicon
Silicon Oxide ETCHING in BHF
Silicon dioxide
n-Silicon
After Photo Resist & Wax removal Removal

11. PRE DEPOSITION
Boron Atoms ambient
Silicon dioxide
Impurity Deposition (Boron/Phosphorous)
n-Silicon
Silicon dioxide
n-Silicon
Boro-silicate Glass and
BORON Atoms

12. After Etching in Glass Etchant:
Boron atoms
Silicon dioxide
n-Silicon

13. DRIVE - IN
Silicon dioxide
p
p
n-Silicon
Silicon dioxide
p
n-Silicon
p
Pre-deposited wafer heated at
High Temperature so impurity
Move into silicon.
Front coating photo
resist layer

14. Silicon dioxide
p
p
Back Oxide etching
BHF
p
Photo resist removal
n-Silicon
Silicon dioxide
p
n-Silicon
Dip in dil. HF to remove oxide if any on the front side and claen

15. Metal Contact Formation
Silicon dioxide
p
p
Aluminium Thin Film
Deposition
n-Silicon
Silicon dioxide
p
n-Silicon
Photo Resist
Aluminium
p

16. U. V Rays
Glass
Aluminium
Silicoon dioxide
p
Photoresist
p
P- Contact
n-Silicon
PHOTOLITHOGRAPHY FOR Metal Contacts
Silicon dioxide
p
p
n-Silicon
Development to remove U.V Exposed Photoresist

17. p
Silicon dioxide
p
n-Silicon
After Aluminium ETCHING
p
Silicon dioxide
p
n-Silicon
Metal Thin Film
Back Metal Contact Formation
p
One Diode Chip after separation
of diode

18. Diodes chips are
separated by scribing
using a diamond
point and packaged in a
suiatable package as
shown in the figure.

19. P-N Fabrication Training is Over