Question

Describe vertical flow based chemical vapour deposition reactors, indicating advantages and disadvantages.

Answer 1

• Vertical flow based chemical vapour deposition reactor technique used to deposit a thin film of material on solid substrate. It is used in wide application in industry from fabrications of microelectronics circuit to deposition of wear resistance coating on machine tool.
• By heating solid substrate leads to reaction in gas phase so that reactants are formed are reacts with surface of solid substrate.
• Increase the heat reactor entrance leads to recirculation of flow at entrance due to volumetric expansion of gas. This recirculation flow forces fresh incoming stream of gas towards the solid substrate.This effect on deposition rate.
• Vertical flow based chemical vapour deposition reactor are used for very uniform deposition.

Advantages :

• Good uniform deposition.
• High throughput.
• Ability to handle large diameter wafers.
• High capacity.

Disadvantages :

• Many gases are used toxic and corrosive so good safety required.
• Purity of chemical is required high.
• Cost is high.