Chemical vapour deposition (CVD)

1. Course code CME397 Course name Surface Engineering
Year/sem 3/6 Unit no 4
Course Instructor: M.Karthikeyan AP/Mech
Chemical vapour deposition (CVD)
 It is a surface coating technique.
 It is also used to synthesize/produce nanomaterials.
Nanomaterials can be synthesized in two ways
 Top-down approach
 Bottom-up approach
CVD comes under the category of bottom-up approach
Preparation of substrate
1. Initially the substrate should be cleaned with emery sheet to remove
any dust or foreign particles.
2. Then the substrate is cleaned using ultrasonication.
3. Finally, the substrate was cleaned with acetone and dried in air.
Procedure for CVD process
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2. 1. Initially the substrate is loaded in the boat.
2. Then the boat is placed inside the quartz tube.
3. Now vacuum is crested to avoid the deposition of impurities.
4. Next argon gas is supplied to heat the substrate, just below the melting
point.
5. If once the temperature is reached, argon gas supply is switched off and
the source gas (example: methane CH4 is used to deposit graphene) is
allowed to pass for the required period.
6. After the deposition period, source gas supply is turned off and the
argon gas is allowed to pass for the purpose of cooling.
7. After the cooling process, the substrate can be unloaded from the quartz
tube and it can be used for further application.