Jf. Horton et Je. Peterson, Rayleigh light scattering measurements of transient gas temperature in a rapid chemical vapor deposition reactor, J HEAT TRAN, 122(1), 2000, pp. 165-170
A laser-induced Rayleigh light scattering (RLS) system was used to measure
transient gas temperatures in a simulated rapid chemical vapor deposition (
RCVD) reactor. The test section geometry was an axisymmetric jet of carrier
gas directed down, impinging on a heated wafer surface. RLS was used to me
asure instantaneous gas temperature at several locations above the wafer as
it was heated from room temperature to 475 K. Gas flow rate and wafer temp
erature correspond to jet Reynolds number Re-i=60, wafer maximum Grashof nu
mber Gr(H)=4.4X10(6), and maximum mixed convection parameter Gr(H)/Re-i(2)
= 1200; all conditions typical of impinging jet reactors common in the nume
rical literature. Uncertainty of RLS transient temperature from a propagate
d error analysis was +/-2-4 K. Peak gas temperature fluctuations were large
(in the order of 25 to 75 degreesC). Both flow visualization and RLS measu
rements showed that the flow field was momentum dominated prior to heating
initiation, but became unstable by Gr(H)/Re-i(2)=5. It then consisted of bu
oyancy-induced plumes and recirculations. Up to the peak wafer temperature,
the flow field continued to be highly three-dimensional, unsteady, and dom
inated by buoyancy. RLS measurements are shown to provide information on ca
rrier gas instantaneous temperature and flow field stability, both critical
issues in RCVD processing.