It explaines different types of chemical vapor deposition techniques.

1. Presented by
SUBRAT KUMAR MAHARANA
M.E. IN MECHANICAL ENGINEERING
JADAVPUR UNIVERSITY,KOLKATA

2. CONTENTS
 What is CVD- Basic Mechanism
 Types of CVD
 Applications of CVD
 Advantages and Limitations
 Conclusion

3. What is CVD?
 CVD is a process in which a desired material is
deposited on a surface by the help of chemical reactions

4. Chemical reactions

5. TYPES OF CVD PROCESSES
 Pressure based: APCVD,LPCVD,UHVCVD
 Vapour characteristics: AACVD,DLICVD
 Types of substrate heating: Hot walled and
cold walled CVD
 Plasma assisted : MPCVD,PECVD,RPCVD
 Atomic Layer CVD: ALCVD
 Combustion CVD: CCVD
 Photo initiated CVD: PICVD

6. ATMOSPHERIC CVD (APCVD)
CVD at atmospheric pressure.
Very low operating cost as no need of
vaccum system.
Prone to oxidation-so less used
It is also used as a surface finishing
process for items such as tools and
turbine blades to improve lifetime and
performance

7. LOW PRESSURE CVD(LPCVD)
 It works at sub-atmospheric pressure(10-1000Pa)
where as the atmospheric pressure is 100000Pa.
 The lower pressure increases the precursor
diffusion through the gas and the mass transfer
rate of the gaseous reactants becomes higher than
the surface-reaction rate.
 Reduced pressures tend to reduce unwanted gas-
phase reactions and improve film uniformity
across the wafer.

8. HOTWALLED AND COLD WALLED CVD
 In hot walled CVD the chamber is heaated by an
external power source and the substrate is heated by
radiation from the heated chamber walls.
 In cold walled CVD the substrate is directly heated by
either by induction or by passing current though the
substrate itself.

9. Plasma enhanced CVD(PECVD)
 CVD uses plasma to enhance the chemical reaction
rate.
 Plasma can be used to decompose a molecule that will
not decompose at a reasonable elevated temperature.
 It can be used to decompose a thermally unstable
molecule but at a much lower temperature(100 -500 c)

10. Combustion CVD(CCVD)
 It is a flame based technique for material deposition.
 It is also called open flame pyrolysis.

11. Photoinitiation CVD(PICVD)
 This process uses UV light to stimulate chemical
reaction.

12. Laser CVD(LCVD)
 LCVD uses a focussed laser beam to heat the substrate.
 It also has the ability to locally heat a part of the
substrate thereby locally driving the CVD reaction at
the surface.
 It is used to deposit micro scale solid patterns.

13. APPLICATIONS
Coatings – Coatings for a variety of
applications such as wear resistance,
corrosion resistance, high temperature
protection.
Semiconductors and related devices –
Integrated circuits, sensors and
optoelectronic devices.
Fiber optics – for telecommunication.

14. Advantages
CVD films are generally quite
conformal, i.e., the ability of a film to
uniformly coat on a complex substrate.
High purity can be obtained.
Economical in production, since many
parts can be coated at the same time.

15. limitations
 Chemical and safety hazards caused by the use of
toxic,
 corrosive, flammable and/or explosive precursor.
Therefore extra steps have to be taken in the handling
of the precursors and in the treatment of the reactor
exhaust.
 High deposition temperatures (often greater than 600
°C) are often unsuitable for structures already
fabricated on substrates.
 Development of thermal stresses

16. THANK YOU