Chapter 9, Problem 9.13P

In the production of many microelectronic devices, continuous chemical vapor deposition (CVD) processes are used to deposit thin and exceptionally uniform silicon dioxide films on silicon wafers. One CVD process involves the reaction between silane and oxygen at a very low pressure.

   $Si{H}_4\left(g\right)+O_2\left(g\right)\to Si{O}_2\left(s\right)+2H_2\left(g\right)$

The feed gas, which contains oxygen and silane in a ratio 8.00 mol O₂/mol SiH₄, enters the reactor at 298 K and 3.00 torr absolute. The reaction products emerge at 1375 K and 3.00 torr absolute. Essentially all of the silane in the feed is consumed.

Taking a basis of 1 m³of feed gas, calculate the moles of each component of the feed and product mixtures and the extent of reaction, $\xi$.

1. Calculate the standard heat of the silane oxidation reaction (kJ). Then, taking the feed and product species at 298 K (25°C) as references, prepare an inlet-outlet enthalpy table and calculate and fill in the component amounts (mol) and specific enthalpies (kJ/mol). (See Example 9.5-1.)
Data

   $\begin{array}{l}{\left(\Delta {\hat{H}}_f^{°}\right)}_{Si{H}_4\left(g\right)}=-61.9kJ/mol,{\left(\Delta {\hat{H}}_f^{°}\right)}_{Si{O}_2\left(s\right)}=-851kJ/mol\\ {\left(C_p\right)}_{Si{H}_4\left(g\right)}\left[kJ/\left(mol\cdot K\right)\right]=0.0118+12.2\times {10}^{-5}T-5.548\times {10}^{-8}{T}^2+6.84\times {10}^{-12}{T}^3\\ {\left(C_p\right)}_{Si{O}_2\left(s\right)}\left[kJ/\left(mol\cdot K\right)\right]=0.04548+3.646\times {10}^{-5}T-1.009\times {10}^3/T^2\end{array}$

The temperatures in the formulas for C_pare in kelvins.

1. Calculate the heat (kJ) that must be transferred to or from the reactor (state which it is). Then
determine the required heat transfer rate (kW) required for a reactor feed of 27.5 m ³/h.