handout 5 - 1 Handout 5 EEL 5225, Fall 2009, H. Xie...

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Unformatted text preview: 1 Handout 5 EEL 5225, Fall 2009, H. Xie Fabrication Technology, Part I b Senturia, Ch. 3, pp. 38-42, Ch. 4, pp. 79-91 f h Agenda B Impurity Doping B Heat Treatment B Example process flows 2 Handout 5 EEL 5225, Fall 2009, H. Xie Impurity Doping s Overview s Ion Implantation s Example Impurity Doping 3 Handout 5 EEL 5225, Fall 2009, H. Xie Impurity Doping – Overview s Typical Process s Predeposition s Introduction of impurities via ion implantation s Drive-in (optional) s Redistribution of impurities via heat treatment s Applications s Doping of p- and n- semiconductors s **Ion implant used almost exclusively compared to solid- gas-source diffusion s Precise dose/depth control &-type impurity &-type impurity &-type impurity P-type impurity diffusion 4 Handout 5 EEL 5225, Fall 2009, H. Xie Ion Implantation s Kinetic bombardment of impurities into semiconductor. +n A Ion current, I +n Projected range, R P Energy, E (keV) ∫ = T o dt nqA I Q Ref: S. A. Campbell, Science and Eng. of Micro. Fab. , 2001. Typical Implanter 5 Handout 5 EEL 5225, Fall 2009, H. Xie s The total implant is the superposition of many of these individual stopping events Ion Implantation Distribution Ref: A. Doolittle Notes, Georgia Tech. p R p R Δ ⊥ Δ R Wafer Surface Projected Range Vertical Straggle Lateral Straggle 6 Handout 5 EEL 5225, Fall 2009, H. Xie Ion Implantation Distribution s Key parameters s Dose, Q (#/cm 2 ), sets: s Doping concentration levels s Ion energy, E (keV), sets: s Projected range , R P , the average distance ion travels into wafer surface s Straggle, the variation in projected range, both normal ( Δ R P ) and transverse ( ) s Model for impurity distribution & p : peak concentration (#/cm 3 ) Gaussian distribution: μ = R p , σ = Δ R p Δ − − = 2 2 ) ( 2 ) ( exp ) ( p p P R R x & x & ∫ ∞ Δ = ≡ 2 ) ( p P R & π dx x & Q ⊥ Δ R s Key parameters s Dose, Q (#/cm 2 ), sets: s Doping concentration levels s Ion energy, E (keV), sets: s Projected range , R P , the average distance ion travels into wafer surface s Straggle, the variation in projected range, both normal ( Δ R P ) and transverse ( ) s Model for impurity distribution 7 Handout 5 EEL 5225, Fall 2009, H. Xie Ion Implantation Depth s Projected range ( R p ) and straggle (sigma) (∆ R p ) for Si Ref. Campbell, p. 108. Note: 1000 Å = 100 nm = 0.1 μm 8 Handout 5 EEL 5225, Fall 2009, H. Xie Junction Formation s Junction depth, x j s Defined as depth into silicon surface where impurity concentration ( N A or N D ) equals background concentration ( N B ) For Implant: B p p j P j & R R x & x & =...
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This note was uploaded on 09/17/2009 for the course EEL 5225 taught by Professor Arnold during the Fall '08 term at University of Florida.

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handout 5 - 1 Handout 5 EEL 5225, Fall 2009, H. Xie...

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