d) If you wanted to increase the growth rate of a transport-limited CVd process what processing variables would be most effective?(List them in decreasing order of efficacy, e.g. v o exp(x)first, etc 5 nts For the fixed length, in the transport-limited regime, in decreasing order of efficacy, we have Pg, yu,, and 5. Phosphorus-doped polysilicon is produced by CVd based on the following reactions Sih(g)e Si(s)+ 2H,(g) 2PH3(g)“2P(s)+3H2(g) Deposition occurs at 1000oC, Ns=5x 10cm", the Si deposition is reaction limited (cn=108cm3,k。=6×10°cm/s),△G=1.0eV. and the deposition of the P is transport limited(c=108cm 3, D=10-xT cm/s, and(pu/n)=0.01 cm.) a)What range of P concentration in the poly-silicon might you expect across a 30 cm diameter wafer? Explain the assumptions you must make to answer this question 10 points. The silicon deposition is reaction limited k=6×105ex 8617×10eV/K×1273K C=10cm Namn=5×102cm3 1.32x10 he phosphorus deposition is transport limited DCR pLu n D=10-3×(1273)2=0.45cm2/s 3×10 phosphorus5 d) If you wanted to increase the growth rate of a transport-limited CVD process, what processing variables would be most effective? (List them in decreasing order of efficacy, e.g. v µ exp(x) first, etc.) 5 points. For the fixed length, in the transport-limited regime, in decreasing order of efficacy, we have Pg, u• ,and T . 5. Phosphorus-doped polysilicon is produced by CVD based on the following reactions: SiH4 (g) ´ Si (s) + 2H2 (g) 2PH3 (g) ´ 2P (s) + 3H2 (g). Deposition occurs at 1000o C, NSi = 5 ¥ 1022 cm-3, the Si deposition is reaction limited (cg = 1018 cm-3, ko = 6 ¥ 105 (cm/s), DG = 1.0 eV), and the deposition of the P is transport limited (cg = 1018 cm-3, Dg = 10-5 ¥ T3/2 cm/s, and (ru/h) 0.5 = 0.01 cm-0.5). a) What range of P concentration in the poly-silicon might you expect across a 30 cm diameter wafer? Explain the assumptions you must make to answer this question. 10 points. The silicon deposition is reaction limited: vsilicon = kCg N k = 6 ¥105 exp -1eV 8.617 ¥10-5 eV /K ¥1273K Ê Ë Á ˆ ¯ ˜ = 66 cm /s Cg =1018 cm-3 Nsilicon = 5 ¥1022 cm-3 vsilicon =1.32 ¥10-3 cm /s The phosphorus deposition is transport limited: v phosphorus = DCg LNP rLm h D =10-5 ¥ (1273) 3 2 = 0.45cm 2 /s v phosphorus = 3¥10-6 L cm /s