Transport

Mass Transport

Introduction to Transport
Convection and Diffusion
Diffusion: Physics and Math
Diffusion Length
Convection and Reynolds Number
Plug Flow, Plug Reactor Model
Poiseuille and Couette Flow
Boundary Layer Flows
Pressure and Knudsen Number

Heat Transport

Introduction to Heat Transport
Heat Transfer Mechanisms
Heat Conduction and Diffusion
Heat Conduction and Plug Flow
Natural Convection
Radiative Heat Transport
Temperature Measurement

What is Heat (Energy) Transport? Why Do We Care?

• Most CVD processes operate at some temperature other than that of the ambient. Sometimes only the sample is heated ("cold-wall reactors"); in other cases the whole process chamber (often a quartz or glass furnace tube) is heated to the process chamber ("hot-wall reactors"). Some processes operate at reduced temperatures (e.g. deposition of parylene from dimer precursors).
• Changes in temperature require transport of heat (thermal energy) from a heating element to the sample. To control and monitor the temperature of the sample, we need to understand the mechanisms by which heat is transported to the sample and the methods by which temperature may be measured.
• The temperature of the gas stream will be affected by its surroundings (including heated walls or substrates), and this temperature is in turn likely to affect the rates of chemical reactions in the gas phase, as well as possibly changing the nature of the fluid flow (natural convection). We need to understand how heat is transported in the gas in order to analyze the effects of local temperature on process behavior.

Return to Tutorial Table of Contents
Book version of the CVD Tutorial