Week-8-implant-I

Week-8-implant-I - EE- 504L :Solid State Processing &...

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EE- 504L :Solid State Processing & Integrated Circuits Dr. Kian Kaviani sieh Ming Electrical Engineering Hsieh Ming Electrical Engineering Dept. University of Southern California Viterbi School of Engineering 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 1
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n Implantation Ion Implantation n Implantation process in which energetic Ion Implantation : A process in which energetic, charged atoms (or molecules) are directly introduced into a substrate 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 2
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Advantages of Ion Implantation vs. iffusion Diffusion 1. Ion implantation is a much more accurate process than diffusion processes. The ion distribution with 5 order of magnitude (E11 – E16 /cm2) vs. only two – three order of magnitude (E13 – E16 / cm2) control with diffusion. 2. Ability to doped with a very low dose (E11 /cm2) which is not possible in diffusion process. 3. Ability to achieve very shallow junctions (< 500 A) which is not possible with diffusion process. 4. Ability to dope very high dose of ions deep inside the semiconductor. 5. Room temperature operation of ion implant allows use of photoresist as the ion masking material which will add to the flexibility of the process. 6. The damages induced in the crystal can be cured with the use of post – implant annealing. 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 3
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purity Profiles of Ion Implantation Impurity Profiles of Ion Implantation (x) = N xp[ 2/2 p N(x) = N 0 exp[- ( x – R p )^2 / 2 Rp ^ 2 ] Where:x : depth into the implanted layer Rp : Projected Ion Range, Statistical average enetration of ions inside the crystal penetration of ions inside the crystal. Rp : Projected Straggle N0 : Maximum or Peak Ion Concentration, which is a function of energy (E) and dose of ions 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 4
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purity Profiles of Ion Implantation Impurity Profiles of Ion Implantation 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 5
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purity Profiles of Ion Implantation Impurity Profiles of Ion Implantation 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 6
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Impurity Profiles of Ion Implantation R : Projected Lateral Straggle, The extent of lateral penetration of ions under the edges of the implant mask. R 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 7
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rojected Range (Rp) for As, P & B Projected Range (Rp) for As, P & B 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 8
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Projected Straggles ( Rp & R ) for As, P & B 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 9
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Relationship between the Ion Dose & Energy with peak Ion Concentration = Dose / ( 2 p ) N 0 Dose / ( π ∆ Rp ) Dose : ions/cm2 (Given) Rp : cm (Function of Ion Energy) N 0 : cm3 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 10
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Relationship between the Ion dose, implant beam current and implantation time = q. dose.(Implanted Area)/ time I q. dose.(Implanted Area)/ time I = q .Q.A / t here: Where: I : Ion Implant Current (A) : Electronic Charge (1 6E23) q : Electronic Charge (1.6E23) Q : Ion Dose (Ions / cm2) A : Wafer Area (Cm2) t : Time it takes to implant one wafer with the area A , cm2 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 11
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unction Depth Junction Depth X j = R p + R p 2ln(N 0 /N B ) Where: N 0 : Peak Ion Concentration Substrate Doping Concentration N B : Substrate Doping Concentration 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 12
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ultiple Implantation Multiple Implantation 1/3/2011 Dr. Kian Kaviani - Spring 2011 - EE-504L 13
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This note was uploaded on 02/23/2011 for the course EE 474 taught by Professor Lingo during the Spring '11 term at USC.

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Week-8-implant-I - EE- 504L :Solid State Processing &...

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