13 Implant 10

13 Implant 10 - Implantation is a key process in VLSI and...

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Unformatted text preview: Implantation is a key process in VLSI and ULSI fabrication dopants are introduced into the silicon using a particle accelerator. purity, quantity and distribution of dopants species are more highly controlled than in thermal diffusion. dopant activation and damage effects require post- implant anneal Implant This lecture covers how dopants are implanted Ion energy eV Ion flux ions.cm-2 .s-1 Physical interactions Damage/ejection Chemical reactions? Etch products By-products? From ions Major parameters Physics and Chemistry is somewhat common in: Ion implantation (this lecture) Dry etch (next lecture) Sputtering (lecture 15) Do these apply for all ion-related processes? Ion implant basics Ion energy High Ion density Low Physical reactions Large Chemical reactions Small By-products Sputter + Wafer Implantation involves a source of high energy ions which strike the wafer and go deep! Technology drivers Implantation is ESSENTIAL for shallow junctions (< 0.5 m) and/or light doses (e.g. V t adjust) Its controllability and uniformity has led to it being used for ALL doping steps Typical processes use 8 - 12 implants Why is control important? Well doping sets depletion layer w Threshold voltage control Shallow contacts Distribution and dose (concentration) control are vital for control of L eff and V t Energy loss mechanisms dE dx S E S E n e = + ( ) ( ) S k E e e = ( ) . 0 5 Two components of energy loss as the ion penetrates the substrate - given by the LSS model (named after its developers) E loss per unit length of ion track Nuclear loss Electronic loss Schematic - loss mechanisms 10 100 1000 keV Loss (keV/ m) B n P n As n S e (E) 1000 100 10 Nuclear loss Electronic loss E S n Nuclear loss at low E - screening 0 0.2 0.4 0.6 Implant nomenclature Mean is called Range (R p ) Gaussian profile Standard deviation is called...
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This note was uploaded on 05/11/2010 for the course EEE EEE-530 taught by Professor Kozicki during the Spring '10 term at ASU.

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13 Implant 10 - Implantation is a key process in VLSI and...

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