1. INTEGRATED CIRCUITS

2.  Introduction
 Brief history
 Scale of integration
 Types of IC’s
 Wafer fabrication process
 IC’s fabrication techniques
 Advantages
 Disadvantages
 Applications
 Conclusion
 References

4.  1940’S – Initial stage.
 1945’s – Bell labs established a group to
develop a semiconductor
replacement for vacuum tubes.
 1947’s – Transistor invented.
 1951’s – Junction transistors invented.
 1958’s – Integrated circuits invented.

5.  Small scale integration (SSI)
 Medium scale integration (MSI)
 Large scale integration (LSI)
 Very large scale integration (VLSI)
 Ultra large scale integration (ULSI)

6.  Wafer scale integration (WSI)
 System on a chip (SOC)
 3D IC’s

7.  Analog IC’s
 Digital IC’s
 Mixed signal IC’s

8. Silicon shaping:
 Removal of ends
 Surface grinding
 Grounding of flats
 Slicing of ingots
 Lapping
 Edge contouring
Chemical etching
Polishing
Chemical cleaning

9.  Silicon is a hard & brittle material.
 Industrial grade diamond is the most suitable
material for shaping & cutting silicon.

10.  Remove seeds and tang ends.
 Metallurgical grade silicon (MGS).
 Cutting is done using a circular saw.

11.  Rotating diamond
grinding tool.
 X-ray diffraction
techniques.

12.  Primary flats
 Secondary flats

13.  Inner diameter
sawing
 Diamond saw

14.  The wafer flatness produced at this step is
better than 2 micro meter.
 Mixture of AL2O3 & glycerin.

15.  Diamond tool.
 Prevents defects.
 Helps in smooth
deposition of
photoresist.

16.  Acid etching:
• acid bath
• etchant
 Alkali etching:
mixture of NaOH:H2O or KOH:H2O

17.  For smooth surface
 Batch wafer
process
 Single wafer
process
 Slurry

18.  Silicon wafers are cleaned chemically to
remove organic films, heavy metals
 Aqueous solution of NH4OH-H2O2, HCL-
H2O2.

19.  Diffusion and ion implantation
 Oxidation and film deposition
 Epitaxial growth
 Lithography
 Etching
 Photo resist
 Deposition

21.  Oxides are grown or deposited on the surface
of the wafer
 Film deposition:
 thermal oxides
 dielectric layers
 polycrystalline oxides
 metal films

22.  The growth of ultra pure layer of crystalline
silicon.
 Approx 3% of silicon wafer.
 Contaminate free for the subsequent
construction of transistor.

24.  Small size
 Low weight
 Easy replacement
 High speed
 High temperature tolerance

25.  Lack of flexibility
 High power requirements

26.  Automobiles
 Appliances
 computers

27.  Modern computing, communication,
manufacturing and transport system
including the internet, all depends on the
existence of integrated circuits.