ELECTRONIC MATERIALS PROCESSING
ELECTRONIC MATERIALS PROCESSING CHE 571
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This 17 page Class Notes was uploaded by Myrna Kunze on Monday October 19, 2015. The Class Notes belongs to CHE 571 at Oregon State University taught by G. Herman in Fall. Since its upload, it has received 28 views. For similar materials see /class/224474/che-571-oregon-state-university in Chemical Engineering at Oregon State University.
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Date Created: 10/19/15
Silicon Chapters 2 3 Wolf and Tauber Crystal Structure Defects From sand to electronic grade silicon Single crystal growth Czochralski growth Floatzone From ingot to wafer Prof Milo Koretsky Chemical Engineering Dept Why Silicon Abundant and cheap lts oxide SiO2 can be grown defect free is easy to grow and has desirable properties Its large band gap allows it to operate at a wide temperature range Prof Milo Koretsky Chemical Engineering Dept Important Characteristics of Silicon Wafers extremely pure 999999999 9 nines oxygen and carbon are carefully controlled some oxygen is beneficial helps to getter MlC s very flat 775g 10u over 300 mm precise diameter 300 mm 02 mm precise resistivity and doping crystalline orientation lt111gt or lt100gt important for doping and for die separation very low crystalline defects very low numbers of surface particles single digits l W Prof Milo Koretsky Chemical Engineering Dept Prof Milo Koretsky Chemical Engineering Dept Crystal Structure trill Prof Milo Koretsky Chemical Engineering Dept Si Crystal Structure Diamond crystal stru ctu re IIKEIIK GI I39ESIUI VJKEIIBIII IIESIUIIKBSIIIII ezmnussy guurwsanr a n u I s n I u a n u u n u I 7 z m n u s s 1 u nanInwnxnr v v J i r I l a k I I I I O H i i a O H i i n i i i I I I I O H El 1 u I 1 a u s I I rimunaiu39 39UDIEHEIIEIIWIIilunliu 4n uuultnnluauun Iauunuuu u r u n n I I G u u l l AI KI D I I n I i I D I I I i l I I I I I I D I I n I I U I In I aliisliiilsllnlill1 linnxiznig w n w a E Alia 49 a a n n t a y anunugar 39 llllllllllllllllmIIIIIIHIIII A I quotI I v quot Igunlut39lnnns39l nlutiq In I rs quot I fr x nun m I x I u u u I a I e a c In m I x I u u w wingingc m I x I d rt A l l m I u i 5 n I uil un t I m I u i 5 n In i W l t l m I u i 5 M 7 I xquot m l n i iili li a i n u m l n i 5 a i A a a v t IE m l n i iili II I I I l I I I l I I l I H l I I I l I l I I l I h I I It I I I l I 139 39Il I I m I I I I u I u III I I u I I m A I m I I I I u r I I I I u I IIIIIV I m I I I I qr l fr l l I K I M v I i n l I I I U u I I I K I m I I I n l I I Iu A I x I I n I I I I U a Ill 3 a I a I iii IHIEIII I l i llhl l I I U n l W I I I I l I 3 I I I I a I I I I l I I H O n s A I n l x 5 I i I I H O I n s h I n l x 5h 7 a a 4 IHII EEIIIEEIA Il I IIllll lHIl39h 39 2 i h i y a 55 3955 391 Face centered II v I 39I I39ll I I I II I I I 543 A 39 555 39 9 ri39 quot quot 3935quot 51555 E 39 3933 quot 39quot 39 SEES I I 39 4 l I I I cubic FCC lattice 6 n39cc 39 v 54539 39 393quot 39 39 a I w Relaw 39 u39 l I n39 l39 I l li t u I WI 39I39IIII I IIIII I N I w 39I39I39 39u39n39 quot I39 II IVF I ll t 39 r t 2 t b 39 3quotE f 355 39quot395quot355E 55 5 quot a O m as I S g 45 5 bg gg a IE5 separated by 14 e39 t at IIIEl ll 5 I I I I I ll iII li ll I 39 II I I 39tttgiatggh 5 Riggs 5 a V body dlagonal quota255Eltr2539 39E 5593 Z quot gait segregate tatg t tgt wwmwm w mw tEE39HEE E39EEEE39 estates rquot 22 3 1 339 5 X 10 atomSCm Slllccrn Prof Milo Koretsky Chemical Engineering Dept Crystal Planes 100 Top View Plane 0 unit cell X 100 Planes defined by Miller indices Their normal direction reciprocals of intercepts of plane with the x y and z axes Seen Prof Milo Koretsky Chemical Engineering Dept Crystal Planes 111 Z Plane of unit cell x Silcen Prof Milo Koretsky Chemical Engineering Dept 100 vs 111 2 See handout Prof Milo Koretsky Chemical Engineering Dept Properties of Si Phase Property Symbol Value Solid bandgap Eg 112 eV intrinsic 27 C 145 X 1010 om 3 carrier 00110 100 C 135 x 1012cm393 Molecular MW 28 gmole Weight 0028 kgmole density p 233 gom3 heat CF 292 J mole391 K391 oapao1ty thermal K 221 s1 m1 K1 oonduot1V1ty emmisivity 8 046 a Prof Milo Koretsky Chemical Engineering Dept Properties of Si Phase Property Symbol Value Solid Liquid m Melting point T m 1685 K Change heat of fusion Ahfus L in 502 X 103 text J mole Li uid density p 242 gcm3 heat capacity CF 272 J molequot1 Kquot1 thermal K 64 J squot1 mquot1 Kquot1 conductivity Prof Milo Koretsky Chemical Engineering Dept Point Defects It is defects that largely determine the lifetime of carriers electrons and linl 0000509398 k 00000000 0 o o oxo o o o x o oxo o o o o o oooooxoco oco looooo cocoooo 0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 Vacancy Interstltlal Prof Milo Koretsky Chemical Engineering Dept 1D Defects St lii 11g Fa ult I Di l ti Precipitate Chemic39 i b ih rih bept HCZ Process flow SiHCl Metallurgrcal 3 Sand I Arc Furnace gt FIUICZIZBd 136d I S parator Carbon 2000 0C Grade SI 300 C V lSiHCl3 lt Electronic 0 CVD 50 C 1 Grade Si 9 if 1 39 11101 j 5102 a Si 02 MW 911 Raw Si Mined from Sand Prof Milo Koretsky Chemical Engineering Dept Frm Sand to EGS HCZ S 39HCZ Sand Arc Furnace Fluidized Bed 1 3 gt Separator Carb39 2000 0C 300 0C lSiHCl3 Electronic 0 CVD 950 C Grade Si 1 Reduction of quartzite to metallurgical grade Si MGS at 2000 CC in an arc furnace 510209 2Cs a Sil 2C0g Ah z 750 k Jl molj Sources of C include wood chips coal and coke MGS formed is about 98 pure Fe 1 Al 05 Cr 005 Mn 002 V 002 Mg 001 Ni 001 Ti 001 Prof Milo Koretsky Chemical Engineering Dept From Sand to EGS Sulbrnerged Electrode QuartziteCoalCoke Wood Chips Furnace Sclhematic of submerged electrode arc furnace 51025 2CS a Sil 2C0g Prof Milo Koretsky Chemical Engineering Dept From Sand to EGS Sand I Arc Furnace Matallurgicagt Fluidized Bed S t Carbon 2000 0c Grade Si 300 0c Spam or ism Electronic 0 CVD 950 C Grade Si 2 Powdered MGS is converted to trichlorosilane at 300 C in a fluidized bed reactor Sis 3ch g a SiHCZ3g H2g Ahr z 250 El molj Must be kept below 325 C to avoid by products Boron BCI3 and phosphorous PCls the major impurit39es a a Silicon Prof Milo Koretsky Chemical Engineering Dept From Sand to EGS Metallurgical Sandgt Arc Furnace gt Flu1d1zed Bed 4 CVD 950 0C Grade Si Carbon 2000 0C Grade Si 300 OC 3 Use Distillation to separate the product mixture 68 steps are used Prof Milo Koretsky Chemical Engineering Dept From Sand to EGS HCI l Metallurgical Sand I Arc Furnace gt Flu1d1zed Bed SiHCI3 ilni i r r39jr Slit i i ii I a silicon raid gt Carbon 2000 0c Grade Si 300 0c Separator ner s Electronic 0 739 i 39 CVD 950 C F i Grade 81 i F i iTE iiiillL i i I wait 4 Chemical Vapor Deposition CVD of polycrystalline electronic grade Si EGS at 950 1100 00 Siemens Process FIGURE 41 Siemens Reactor for SB Silicon a Ahr z EGS is the purest material routinely available on a Prof Milo Koretsky Chemical Engineering Dept Czochralski Cz Growth CZ growth Movie 300 mm Si ingot 939 i 1 i gt Lr i ll quot L39V39ft 139 J y r i if l I I I I quot a I Melterr Emaile 0 391 Prof Milo KoreterOUl tesy Of Kayex Corp 1 Chemical Engineering Dept 1O Modeling of CZ Growth Processes Inputs Geometry Properties Governing Equations Mass Momentum Energy Charge Outputs Growth velocity Initial Conditions eg pull rate rotation rate melt temperature Concentrations Diameter 1 Maximum growth velocity of the Si Boule Energy 2 Impurity concentrations along the Boule Mass Prof Milo Koretsky Chemical Engineering Dept Modes of Heat Transfer Prof Milo Koretsky Chemical Engineering Dept 11 9 in out generated accumulation A 1D control volume I Q5 2 L I Qlf I V8 I T I Tm I I I I I 0 Z Prof Milo Koretsky Chemical Engineering Dept in out generated VP A cond ctio I radlatlon AZ R W area 2 J39L RAZ I accumulation Z conduction Prof Milo Koretsky Chemical Engineering Dept 12 SolidLiquid Phase Diagram Liquid Eutectic Solid b pox and liquid Solid b 39 Solid a and b Solid a and liquid Prof Milo Koretsky Chemical Engineering Dept Solid a T Segregation Coefficient k0 T Liquid Eutectic po39 t Solid b R and liquid SOid a a and liquid Prof Milo Koretsky Chemical Engineering Dept Liquidus 8rd db k0 ClS Z Ci C 13 Values of k0 Element k0 Values for common B O 8 dopants and impurities 1 Ga 8 x 103 ko Ci As 03 Elements tend to segregate Sb 039023 to the liquid except 0 O 14 Al 2 x 10393 Pulled crystals contain C 006 dopants 1018 cm393 oxygen and C 1016 cm393 Prof Milo Koretsky Chemical Engineering Dept Impurity Distribution Model Prof Milo Koretsky Chemical Engineering Dept Effective distribution coefficient ke iiquid miid hulk mtquot v ll ll M in hiti im kitCi 13 16 3 18 D 152 139 a h m 2 090 k ldC ldC kl 0 O V dz D dZZ e 14ka k0 1 k0exp Vlc3Dl Silicon Prof Milo Koretsky Chemical Engineering Dept S k0 Z Ci P lysilic n Ing t 39 Emil Single Crystal Eli Silicon Prof Milo Koretsky Chemical Engineering Dept 15 Comparision 39 CZ Growth More prevalent Cheaper Larger wafer sizes 300 mm Reusable materials Can handle thermal stresses better Float Zone Higher purity Specialized applications Prof Milo Koretsky Chemical Engineering Dept Sinai From Boule to wafer Process Movies Crystal Growth I War Lapping and Edge Grind I J1 n o A ll Shaping I Cleaning I Etching I 3 J1 Jl Wafer Slicing I Inspection I Polishing I Prof Milo Koretsky Chemical Engineering Dept Packaging I Silcon Hong Xiao 16 From Boule to wafer After Lapping After Etch Aft er CMP Q A tom 2 a v 3 IVER5 H39Emef qE After Wafer Sawing L V 76 um m 914 pm Process Movies 1quot 439 76 um Prva Ev w T After Edge Rounding 1 I 914 pm i39 39 I i 39Flli I l I h quot T s 125 Mm 814 111171 125 um I 3750 pm 139 Virtually Defect F me I 725 pm Prof Milo Koretsky Chemical Engineering Dept Hong Xiao Wafer Dimensions Diameter Thickness Area Weight Weight25 mm Mm omz grams Wafers lbs 150 675 i 20 17671 28 15 200 725 i 20 31416 5308 3 300 775 i 20 70686 12764 7 400 825 i 20 125664 24156 13 Si ingot cut amp polished to wafer Prof Milo Koretsky Chemical Engineering Dept 17
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