МММ / 01_Layer_Deposition_Thermal_Oxidation_and_CVD

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Growth Kinetics

Governed primarily by the steps

1.Mass Transfer

2.Surface Reaction

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Solution

 Two limiting cases:

Growth rates in both regimes is linear with time.

•Reaction always occurs at the growing surface

•The diffusion is through a gas region of constant thickness not a growing solid region as in oxidation.

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Atmospheric Pressure CVD

APCVD for epitaxial Si deposition

SiCl4 2H2 Si 4HCl

A ‘Cold Wall’ Reactor

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OUTLINE

Thermal Oxidation and Model

Factors Affecting Kinetics

Future Trends: Oxidation

CVD and Model

Factors Affecting Kinetics

o Future Trends: CVD

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Factors Affecting Growth

Boundary Layer Effects

Depletion Effects

Unintentional Doping

Pressure

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Boundary Layer Effects

Continuous gas flow

Diffusion of reactants

Boundary layer

Deposited film

Silicon substrate

A Detailed Picture of Deposition Process

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Velocity Profile

Gas flow Gas flow

Boundary layer

Boundary layer

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Solution: Reactor Geometry

Effect important in Transfer limited regime

Susceptor is slightly tilted to minimize effect.