- 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.
|
