6.152J3.155J CRYSTAL GROWTH reviewed 6.12J/3.155J Microelectronic processing COnfined CZ Meniscus controlled Zone freezing horizontal 00● Larger radi variations than CZ vertical 团B2O3 N。v.26,2003 ntroduction of dopants via melt 6.12J/3.155J Microelectronic processing Different dopants have different solubilities in solid Define segregation coefficient, k, as ratio of dopant concentrations solid/melt: k-Cs k=0.00203080250350.023 k< 1 implies only a small fraction of dopant moves into solid concentration builds up in melt as S/L interface advances This in tum drives up amount transferred to solid as a function of position in crystal (let x- fraction solidified) Nov.26,20036.152J/3.155J 13 25 Nov.26 , 2003 6.12J / 3.155J Microelectronic processing CRYSTAL GROWTH reviewed 1 Confined Normal freezing (Bridgman) Crystal horizontal vertical Crystal B2O3 Si 2 CZ Meniscus controlled LEC Pull from solution Crystal Crystal Floating zone feed rod highest￾purity crystal; Larger radial variations than CZ 3 Zone melting poly poly Largest crystals: 300 mm diameter 26 Nov.26 , 2003 6.12J / 3.155J Microelectronic processing Introduction of dopants via melt Different dopants have different solubilities in solid Define segregation coefficient, k, as ratio of dopant concentrations solid/melt: k = Cs Cl k = 0.002 0.3 0.8 0.25 0.35 0.023 Al As B O P Sb k < 1 implies only a small fraction of dopant moves into solid; concentration builds up in melt as S/L interface advances… This in turn drives up amount transferred to solid… We can calculate the dopant/impurity concentration as a function of position in crystal (let x = fraction solidified)…