Elementary Principles 129 - 5.34 3.74 SCMM n a mol min...

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Unformatted text preview: 5.34 3.74 SCMM n a ( mol / min) 0.220 DCS 0.780 N 2 O Vb ( m 3 / min) @900 C, 604 mtorr 60% DCS conversion n1 (mol DCS / min) n 2 (mol N 2 O / min) n b (mol / min) n 3 (mol N 2 / min) n 4 (mol HCl(g) / min) U | V | W SiH 2 Cl 2(g) + 2 N 2 O (g) SiO 2(s) + 2 N 2(g) + 2 HCl (g) a. na = 60% conversion: n1 = 1- 0.60 mol gFGH 0.220 mol DCS IJK b167 mol / ming = 14.7 mol DCS / min mol DCS DCS reacted: b0.60gb0.220gb167g = 22.04 mol DCS reacted / min min 3.74 m3 (STP) 103 mol =167 mol / min min 22.4 m3 (STP) b N 2 O balance: n 2 = 0.780 167 - N 2 balance: n 3 = b g mol N O min 2 22.04 mol DCS 2 mol N 2 O = 8618 mol N 2 O / min . mol DCS min 22.04 mol DCS 2 mol N 2 = 44.08 mol N 2 / min min mol DCS HCl balance: n 4 = 22.04 mol DCS 2 mol HCl = 44.08 mol HCl / min mol DCS min n B = n1 + n 2 + n 3 + n 4 = 189 mol / min VB = b. n B RT 189 mol 62.36 L torr 0.001 m3 1173 K = = 2.29 104 m3 / min P min mol K L 0.604 torr p DCS = x DCS P= p N2O n1 14.7 mol DCS/min P= 604 mtorr=47.0 mtorr nB 189 mol/min n 86.2 mol N 2 O/min = x N 2O P= 2 P= 604 mtorr=275.5 mtorr nB 189 mol/min r=3.16 10-8 p DCS p N 2O 0.65 = 3.16 10-8 ( 47.0 MW )( 275.5 )0.65 = 5.7 10-5 mol SiO 2 m2 s c. h(A)=r t SiO2 5 = 5.7 10-5 mol SiO 2 60 s 120 min 60.09 g/mol 1010 A min m2 s 2.25 106 g/m3 1 m (Table B.1) =1.1 10 A The films will be thicker closer to the entrance where the lower conversion yields higher pDCS and p N 2 O values, which in turn yields a higher deposition rate. 5-17 ...
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