Substrates and Epitaxy in III-V Manufacturing Rober obert Y t Yank anka 20 2010 CS 0 CS MANTECH W MANTECH Workshop shop
Ov Over ervie view • Substrat Substrate Manuf Manufacturing Ov cturing Over ervie view • Metal-Organic Chemical V Metal-Organic Chemical Vapor Deposition (MOCVD) por Deposition (MOCVD) Basics Basics • Molecular Beam Epitaxy (MBE) Molecular Beam Epitaxy (MBE) Basics Basics • Epiw Epiwaf afer Charact er Characterization rization • RFMD Epiw RFMD Epiwaf afer Pr er Production Ov oduction Over ervie view 2010 CS MANTECH Workshop Session 2 2
Substrate Manufacturing Overview 2010 CS MANTECH Workshop Session 2 3
Pr Process Flo ocess Flow w of of GaAs GaAs Substrat Substrate Pr e Production oduction Single Crystal Growth Cylindrical Grinding Slicing Edge Rounding Laser Marking Polishing Characterization & Inspection 2010 CS MANTECH Workshop Session 2 4
Substrat Substrates – es – Boule Gro oule Growth wth Techniques niques Growing SolidLiquid As Seed Cooling Solid As Seed Melting Point low Temperature Profile Czochralski (Cz) Gr Czochralski (Cz) Growth wth Horiz Horizontal Bridgman (HB) Gr ontal Bridgman (HB) Growth th 2010 CS MANTECH Workshop Session 2 5
Substrat Substrates – es – LEC vs. V EC vs. Vertical Boat ical Boat Furnace M Fu Moves Boule Moves Boule Mo Liquid Encapsulat Liq id Encapsulated ed Ver ertical Boat ical Boat Czochralski (LEC) Czochralski (LEC) 2010 CS MANTECH Workshop Session 2 6
Substrate – Substrat e – VB VB vs. vs. VGF GF Shorter Ingo Shor Ingot Longer Ingo Longer Ingot Ver ertical Boat ical Boat vs. vs. Ver ertical ical Gradient Gradient Freeze reeze 2010 CS MANTECH Workshop Session 2 7
Substrat Substrates – es – Grinding Grinding and and Slicing Slicing Wire Saw As sliced Wafers 2010 CS MANTECH Workshop Session 2 8
Substrates – Edge Beveling and Polishing Edge Be Edge Beveling ling La Laser Ma r Marki rking ng Double-Side P Double-Side Polishing lishing 2010 CS MANTECH Workshop Session 2 9
Substrat Substrates – es – Inspection and Inspection and Charact Characterization rization Sur Surface Inspection ace Inspection Substr Substrat ate Flatness e Flatness 2010 CS MANTECH Workshop Session 2 10
Substrat Substrates – es – Inspection and Inspection and Charact Characterization rization • Etch Pit Etch Pit Decoration (K Decoration (KOH) OH) – Chemical e Chemical etch used t tch used to det determine dislocation density rmine dislocation density • Electrical Charact Electrical Characterization rization – Hall and Hall and non-contact resistivit non-contact resistivity measur y measurements are ements are performed on the seed and per ormed on the seed and tail t tail to de determine the ermine the electrical characteristics of electrical charact eristics of the boule the boule 2010 CS MANTECH Workshop Session 2 11
MOCVD Basics 2010 CS MANTECH Workshop Session 2 12
Epitaxial Cr Epitaxial Crystal ystal Gr Growth wth • Epitaxy Epitaxy – is is deriv derived fr ed from the Greek w om the Greek word meaning “or d meaning “ordered upon” dered upon” – Epitaxy is Epitaxy is the gr the growth of wth of thin thin single cr single crys ystals tals of one mat of one material erial on on the the cr crystal f ystal face ce of of the same the same (homoepitaxy) or (homoepitaxy) or ano another (he ther (heter eroepitaxy) oepitaxy) material, such that the tw mat erial, such that the two mat o materials ha erials have a e a def defined, relativ ined, relative e structural orientation structural orientation • Two main R o main Rules of les of epitaxy epitaxy – Matc Matching of hing of Symme Symmetr try be y betw tween the subs een the substrat trate and e and the epila the epilayer er – Misf Misfit be it betw tween lattice cons een lattice constants of subs tants of substrat trate and e and epila epilayer should be er should be minimal minimal • Exam Examples of ples of Epitaxy:- Epitaxy:- – GaAs GaAs on on GaAs GaAs (Homoepitaxy) (misf (Homoepitaxy) (misfit v it value = lue = 0) 0) – AlGaAs on GaAs AlGaAs on GaAs (He (Heter eroepitaxy) oepitaxy) (misf (misfit it value > 0) lue > 0) – InGaAs InGaAs on on GaAs GaAs (He (Heter eroepitaxy) (misf oepitaxy) (misfit v it value >> lue >> 0) 0) 2010 CS MANTECH Workshop Session 2 13
Metal Organic Chemical V Metal Organic Chemical Vapor apor Deposition Deposition • First document First documented in 1 ed in 1963 b 963 by Har y Harold Manase ld Manasevit f vit for silicon r silicon on sapphire at R on sapphire at Rockw ckwell Corporation ell Corporation • Manase Manasevit gre vit grew GaAs on sapphire in 1 GaAs on sapphire in 1968 968 • Gr Growth in th involv lves the transpor es the transport of t of me metal-organic and tal-organic and hydride dride precursors t precursors to heat heated substrat ed substrates where the es where they p pyrolize, lea lize, leaving ing the gr the growth species on the substrat th species on the substrate sur e surface ace • Also ref Also referr erred t ed to as (LP-, AP-) OMCVD, MO as (LP-, AP-) OMCVD, MOVPE, OMVPE VPE, OMVPE 2010 CS MANTECH Workshop Session 2 14
Metal Organic Chemical V Metal Organic Chemical Vapor apor Deposition Deposition • MOCVD is capable of MOCVD is capable of high gr high growth th rat rates, making es, making it the most it the most widely used t widely used techniq echnique f ue for the manuf r the manufacture of cture of optical optical devices such as LED’s de vices such as LED’s • At lo t lower gr er growth rat th rates, MOCVD can es, MOCVD can pr produce abrupt oduce abrupt int inter erfaces, allo ces, allowing it’s application t wing it’s application to RF RF de devices such as vices such as HBT’s and FET’s HBT’s and FET’s 2010 CS MANTECH Workshop Session 2 15
Metal Organic Chemical V Metal Organic Chemical Vapor apor Deposition Deposition • Sour Source mat ce materials f rials for MOCVD are e r MOCVD are extremely hazar tremely hazardous, dous, req requiring rigor uiring rigorous monit us monitoring and oring and handling pr handling procedures ocedures – Me Metal-organics are tal-organics are toxic and xic and pyr yrophoric phoric – Hydrides are Hydrides are highly t highly toxic xic – Hydr Hydrogen ogen carrier gas is e carrier gas is explosiv xplosive • Maint Maintenance cy enance cycles driv cles driven b en by coating of coating of reaction chamber reaction chamber – Req equires relativ uires relatively freq ely frequent cleaning uent cleaning to remo remove mat material fr erial from om system com syst em components and onents and reduce reduce par particulat ticulates in es in the chamber the chamber – Syst System em do downtime wntime is is on on the or the order of hour der of hours 2010 CS MANTECH Workshop Session 2 16
MOCVD – Syst MOCVD – ystem Block Diagram m Block Diagram 2010 CS MANTECH Workshop Session 2 17
MOCVD – MOCVD – Syst ystem Pho m Photograph ograph 2010 CS MANTECH Workshop Session 2 18
MOCVD – Syst MOCVD – ystem Schematic m Schematic 2010 CS MANTECH Workshop Session 2 19
MOCVD – MOCVD – Flo low w Contr Control ol • Mass Flo Mass Flow Contr Controller (MFC) ller (MFC) – A A por portion of the gas tion of the gas flo flow passes thr passes through a ugh a tube incorporating tw tube incorporating two o temperature sensor erature sensors – A A tem emperature dif erature difference results that is erence results that is pr propor oportional t tional to the mass the mass flo flow thr through the contr ugh the controller ller 2010 CS MANTECH Workshop Session 2 20
MOCVD – MOCVD – Sour ources es MO Bubbler MO Bubbler Carrier gas (H 2 ) flowing through the bubbler picks up MO vapor from the liquid Typical MOCVD Sour pical MOCVD Sources ces Group III: Tri-methyl gallium, Tri-methyl aluminum, Tri-methyl indium Group V: Arsine, Phosphine, Ammonia, Tertiary-butyl arsine (TBAs), Tertiary-butyl phosphine (TBP) Dopants: Carbon-tetrabromide, Disilane, Di-methyl zinc 2010 CS MANTECH Workshop Session 2 21
MOCVD - Growth MOCVD - wth Dynamics Dynamics CH 3 radical AsH 3 H 2 TMGa V J Diffusion δ 0 • Sour Source molecules mix ce molecules mixed int d into a a carr carrie ier gas (h gas (hydr ydrogen gen) with ) with mid-str mid-stream v velocity elocity V V • Frictio iction reduce reduces gas v s gas velocity t locity to near zer near zero at sur at surfaces aces • Sour Sources must dif ces must diffuse thr use through the near st ugh the near stagnant bo nant boundar undary l layer a er above s e subs bstrat ate e • Precursor decom Precursor decomposition osition • Sur Surface adsor ace adsorption & tion & dif diffusion usion incor incorporation oration and and gr growth th • Gr Growth wth rat rate depen depends upon s upon pressure, flo pressure, flow rat w rate and t and temperatu erature 2010 CS MANTECH Workshop Session 2 22
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