FROM SILICA TO SILICON WAFER The Silicon Single

FROM SILICA TO SILICON WAFER The Silicon Single Crystal and Wafers Manufacturing Version 2. 3 En Silicon V 2. 3 En

VPS This presentation was prepared for the needs of the company ON Semiconductor with the aim to approximate the production principles of single crystal silicon ingots and silicon wafers. The manufacturing process details, pictures and video clips come from the company TEROSIL, a. s. based in Roznov pod Radhostem, Czech Republic, we appreciate their friendly help in compiling the presentation. In our effort to continuously improve our products we thank you in advance for your comments, which will help us in the preparing of further versions. Piestany, August 2001 VPS s. r. o. , P. O. Box B-11, Partizanska 31, 921 01 Piestany 1, Slovak Republic tel. , fax. : +421 33 7730151, email: vps@vps. sk Silicon V 2. 3 En 2

Controlling the Presentation Mouse Control Video A click of the left mouse button, unless the cursor is on a control button or on a video, moves the presentation one step forward. If there is a video on the slide, it is in the brown frame, similarly to the picture below. By locating the cursor on the video, the shape of the cursor will change to character. Clicking on the left mouse button will start the video. Clicking the left mouse on the running video will stop it. Keyboard Control The N key has the same function as the left mouse button (independent of the cursor position). The P key has the opposite function, it means one step backward. Press Esc to finish the presentation. Control Buttons on the Picture By locating the cursor on a button, the shape of the cursor will be changed into character. Clicking the left mouse will stimulate its function then. transition to the slide Contents return to the last displayed slide next slide end of presentation Silicon V 2. 3 En If you do notice an animation action press the P key (Previous) and then start the animation with the N key (Next). 3

Contents Introduction What is Inside an Electronic Device? Silicon - the Structure Silicon - Inside the Single Crystalline Defects Doping Silicon Wafer Silicon Obtaining Polycrystalline Silicon Wafer Manufacturing Wafer Edge Grinding Double-Sided Lapping Stress Relief Etching Machine Backside Treatment CVD Equipment Polishing Machine Chemical Cleaning Inspection Scrubbing Final Inspection Czochralski Crystal Growth Czochralski Puller Crystal-Melt Interface Oxygen and Carbon in Silicon Crystal Segregation Coefficient Single Crystal Ingot Epitaxy Epitaxial Reactor Epitaxial Layer Characteristics Ingot Shaping and Testing Cropped Ingot Appendix Clean Rooms Some Special Units Clicking on this box will navigate you to the Controlling the Presentation slide Silicon V 2. 3 En 4

Introduction The company TEROSIL, a. s. , located in Roznov pod Radhostem, Czech Republic, is producer of silicon single crystals, wafers and epitaxial layers for microelectronic device fabrication. TEROSIL, a. s. is a non wholly owned subsidiary of ON Semiconductor, global supplier of high-performance broadband power management integrated circuits and standard semiconductors. Silicon V 2. 3 En 5

What is Inside an Electronic Device? The If This webasic small remove material piece the of black of matter a material chip is is called a from semiconductor chip. the After package, ansilicon. we can see the enlargement weleads can see leading its structure. up to a small piece of matter inside which the whole function of an electronic device proceeds. Silicon V 2. 3 En 6

Silicon does is available not occur in great naturally abundance in its elemental on the Earth. state. The It occurs Earth in is made up offorms, compound approximately the principal 40%ones iron (Fe), being 28% silicates oxygen and(O quartz. 2) and 14, 5% silicon. Quartz (Si. O 2) is Inthe theprimary Earth´s source crust, silicon of silicon is even in thethe semiconductor second most abundant element - the crust contains 28% of silicon. industry. Melting point 1 413°C Boiling point 2 355°C Density 2 332 kg/m 3 Hardness 7 on Mohs´s scale Energy bandgap Eg = 1, 12 e. V Atomic density 5. 1022 atom/cm 3 Silicon V 2. 3 En 7

Silicon - the Structure 3 nm a = 0, 54 It is Silicon If Each wenecessary move silicon is a chemical crystallographic aatom copy to add has of element this that four structure silicon neighbors, fromis has the by diamond 1/4 which group of the it. IV in thelattice. type main forms appropriate diagonal, Periodic a bond It properties with. istable. both based thefor on original semiconductor a faceand centered the shifted chips cubic structure atoms only when form -a the acube diamond atoms withinatoms type the whole lattice. in itsvolume verticesofand the in theare chip wall arranged centers. exactly according to this structure. Such and arrangement is called single crystal. A view of a fictitious observer inside the silicon single crystal looks like the following picture. 28, 0885 14 Si 2, 33 g/cm 3 Silicon V 2. 3 En 8

Silicon - Inside the Single Crystal Silicon V 2. 3 En 9

Crystalline Defects In screw Any An A fact, atom additional edge imperfection variety dislocation missing dislocation atom of defects from in occupying the can appears the crystalline be does regular described as aexist. site if crystal an structure inbetween Defect extra as atomic site plane visualization isgives considered regular layers has rise been partly sites tocan aainserted defect. vacancy. isbe cut called with A defect an into scissors achieved intersticial. thecan crystal. and byinfluence selective shifted each the etching electrical other. of silicon and mechanical surface. The properties crystalline of a crystal. To defects could demonstrate then appear various like demonstrated kinds of crystalline on thedefects microphotograph. a simplified crystalline structure is used (not silicon). Silicon V 2. 3 En Vacancy Edge dislocation Interstitial Screw dislocation 10

The range Presence Physically, Only a very of of boron small some dopant presence amount chemical concentration ofcauses elements a dopant used a different is - dopants sufficient in themechanism semiconductor infor silicon, doping can of silicon. electric 14 to 20 3. Silicon substantially current The industry unittransfer is of 10 a influence dopant in 10 silicon concentration the of than dopant silicon phosphorus atoms/cm electric is the number conductivity. or arsenic. of dopant lattice Silicon Boron, itself atoms doped 22 atoms/cm 3 usually 3. forwith phosphorus, with per contains unit boron volume 5. 10 is arsenic called of silicon, the and P-type antimony. silicon given arewhile especially in #atoms/cm siliconused doped this purpose. phosphorus, arsenic or antimony is called the N-type one. B Boron IV. A 30. 97376 V. A 15 28. 0855 14 Phosphorus 74, 9216 Si Silicon P 33 As Arsenic 121. 75 51 Sb (Negative) 5 III. A Conductivity type N 10, 81 (Positive) Conductivity type P Doping Antimony Silicon V 2. 3 En 11

Silicon Wafer Secondary Flat P <100> Primary Flat <111> Silicon V 2. 3 En A chip For The that silicon crystallographic conductivity wafers next isreason, very slides wafer aresmall, fabricated will many (P is provide round-shaped. or just orientation, N) chips atype by few deeper are cutting and square processed in arespect The details from silicon millimeters. diameters aof to wafer athe It would together of crystallographic monocrystalline silicon 100, be wafer 125, indifficult, one 150 surface, manufacturing slice orientation silicon mm if not of or iscylinder semiconductor even important more are process. impossible, are encoded pulled commonly for the from - silicon in to wafer aproduce molten used. each wafer. A properties. relative silicon 100 chip mm At inposition special the individually. wafer In end practice, of equipment. isofprimary about thethe process half orientations andofsecondary millimeter the wafer according is flat thick. cut onup to into pictures Already the each individual wafer. the wafer are The chips. used top material side andofthey issilicon doped are wafer classified and itisishighly Pasor Ntype then. <111> polished. or <100> 12

Silicon Obtaining Quartz Although At Metallurgical the very highly first grade step pure, silicon the thisquartz silicon is notsand pure doesisenough not transformed formfor the into thecrystal semiconductor single silicon. lattice. technology. This silicon, It is known Thus known as it is a aspolycrystalline converted metallurgical to grade silicon, trichlorsilane silicon or polysilicon. (Si. HCl is obtained by chemical can be cleaned reactionbyof 3), which quartz distillation, The polycrystalline with and carbon then(C). electronic this trichlorsilane grade silicon, is reacted the next with hydrogen slide will show (H how it looks produce like, highly is thepurified raw material 2) to electronic for single crystal grade silicon. production. Si. O 2 + 2 C Si + 2 CO Metallurgical grade silicon Si + 3 HCl Si. HCl 3 + H 2 Trichlorosilane cleaning Si. HCl 3 + H 2 Silicon V 2. 3 En Si + 3 HCl Electronic grade silicon 13

Polycristalline Silicon V 2. 3 En 14

Chapter 1 Overview Introduction What is Inside an Electronic Device? Silicon - the Structure Silicon - Inside the Single Crystalline Defects Doping Silicon Wafer Silicon Obtaining Polycrystalline Silicon Czochralski Crystal Growth Czochralski Puller Crystal-Melt Interface Oxygen and Carbon in Silicon Crystal Segregation Coefficient Single Crystal Ingot Shaping and Testing Cropped Ingot Silicon V 2. 3 En Wafer Manufacturing Wafer Edge Grinding Double-Sided Lapping Stress Relief Etching Machine Backside Treatment CVD Equipment Polishing Machine Chemical Cleaning Inspection Scrubbing Final Inspection Epitaxy Epitaxial Reactor Epitaxial Layer Characteristics Appendix Clean Rooms Some Special Units 15

Czochralski Crystal Growth Onthe Reachnig The Both In 1918, this the goal crystallographic pull crystal polysilicon the final initial enclosed rate Czochralski growing isthe phase, is to phase, isprogressively desired transform then charge video, crystal the decreased orientation described diameter pull is pull there raw and melted speed rate grown materials the are aand of isin crucible is "shoulder" the process high the and the increased the particular seed into quartz pulled to diameter rotate maintain inawill is which silicon out tobe asof ofa single adapted crucible. a formed the indicated reduce phases small crystal melt. crystal. the on diameter ofby The by athe is crystal growing single arrows. increased crystal is critical The growing pulled for diameter. quartz crystal. the seed The process from crystal to growing melt crucible ingot the isa. Itthen When parameters melt. desired has is shape. growth consumed, crystal. dipped is tothe Since loaded be size. crystal process. chosen This into then that This with the must body this in the method polysilicon accordance silicon procedure second be therefore is removed controlled melt. part has the is (see from to The been of called crucible are the photo) the seed the significally final initial necking melt temperatures, lifts isand silicon growth rotated atoquick the and keep refined wafer dopant. is and its temperature melt called purpose the orientation and simultaneously level A pull crowning. remain seed rate, at is to the the most popular crystal required. pulled-up eliminate rotation same change height. isis rates also dislocations from induced. method and loaded thelow melt. A in thin to from pressure the A produce "tail" crystal the puller. on crystal. argon high grows the crystal ambient. quality at theend single crystals. the interface reduces following impactthe of thermal crystallographic shock onstructure the rest of the crystal. seed. Quartz crucible Seed chuck rotation Seed Shoulder chuck Seed Neck Crown Graphite crucible (susceptor) Body Tail Melt Graphite heater Crucible shaft Crucible rotation Silicon V 2. 3 En 16

Czochralski Puller Argon inlet A graphite Finally, The An isolation quartz lift whole Czochralski (seed theheating system crucible last valve chuck part puller allows is element is of and placed the supported the schematical cable) access component heat isinplaced vacuum holds zone to by upper drawing ais around the graphite containing a chamber thermal seed chamber can the crucible and be the with shield siliconkeeping which graphite eliminating growing water-cooled while compared serves melt. crystal crucible with the The jacket. simultaneously the heat real during crucible - controled susceptor. equipment losses. Monitoring thematerial process ambient aspicture system the must enabling heat innext. lower be (pyrometer susceptor. chosen the vacuum such and that itcrucibles Both controlled camera) chamber. reacts and pullvery computer rate areslowly placed and control rotation. with on a the graphite melt. growth The shaft process. only enabling material the rotation thatand canlifting. be used is quartz. Quartz crucible Isolation valve Seed chuck rotation Cable Seed chuck Camera (diameter control) Graphite crucible Visor Graphite heater Thermal shield Optical pyrometer Crucible shaft Water cooled jacket To vacuum pump Electric current lead-in Silicon V 2. 3 En Crucible rotation 17

Crystal-Melt Interface Melt A The During good fundamental area crystallization flows crystal control between are growth, also of process the takes the generated temperature the melt place behind melt and by at flow crystal the atpattern the rotation crystal-melt growth has interface to inof of the beathe between maintained interface. crucible crystal involves and plays the The the atcrystal the an shape crucible the important silicon transformation and of the and the freezing interface role by melt pulling ofis point. crystal-melt of crucial. directly aofliquid This the. Ais crystal. into good thea solid. To control coldest influences interface During crystal of region grow shape theheat growth, crystalline a inand crystal, the flow dopant melt, athroughout the combination perfection otherwise variation. atoms the ofand solidification of the The interface crystal the liquid and is must the will impurity spontaneous crucible occur critical organize rotation distribution incondition other melt themselves isparts flow used throughout fororiginates as that. to well. generate as they the Heat from become section. the inputs temperature desired part The and of the solid. outputs concave differences melt flowmust shape -This right in be the underlines helps bottom monitored meltto-picture. left remove the and bottom importance be dislocations regulated picture. of good to and is controlproper insure maintained of the during process crystal thegrowth. at crystal the interface body growth. between the melt and the crystal. Crystal cross section (black) Crystal - melt interface Melt Heat flow Crystal rotation Melt flow Convex crystal-melt interface Heat input Heat output no rotation Silicon V 2. 3 En Melt flow Concave crystal-melt interface Crucible rotation 18

Oxygen and Carbon in Silicon Crystal Traces of Oxygen Carbon impurities isother the most impurities originate common are from impurity also the present polysilicon in the crystal. charge crystal. Its and main the from Their source concentration reaction is thebetween crucible is lowerthe material than graphite that- quartz ofheating carbon (Si. O element and they 2). This surface and accumulate silicon is inmonoxide in contact the melt with evaporated residue the silicon leftfrom inmelt. thecrucible. The melt. reaction Carbon between has muchthe lower silicon concentration melt and the than crucible oxygen produces in the crystal. silicon monoxide (Si. O). Most of the silicon monoxide evaporates from the melt surface but a small quantity stays in the melt. Si. O + 2 C CO, CO 2 Si. O Si. C + CO CO, CO 2 Si. O Quartz crucible Graphite heater Graphite crucible Silicon V 2. 3 En 19

Segregation Coefficient Element dopants metals The One In For Most the example, dopant of ofcrystal the elements key concentration growth phosphorus operations have process, segregation has in in the crystal there a segregation crystal are coefficient pulling will twois be phases coefficient less the introduction lowest thanatunity. the of the at 0, 35. interface Due oftop a. That specific to end this, -is, the and near only amount solid thethe ahighest crystal part interface, of of dopant and at the into liquid the dopant bottom the end concentration is crystal. melt. integrated of the Between The ingot. dopant into in the An crystal is example two crystal. added phases, will The to ofbe the arest 0, 35 is polysilicon redistribution times rejected dopant the concentration back concentration charge of into thethe ordopant melt profile melt. of in phosphorus takes Itthe along results crucible. place. crystal in in dopant This the is is measured melt. accumulation illustrated Therefore, on in term the in graph oforder melt a segregation below. as to achieve crystal Heavy coefficient growth a metals given as a ratio dopant proceeds. have very level of low Inconcentrations in turn, segregation thebecause crystal, the coefficients the of the dopant concentration dopant which in the two phases. concentration increases results in further in the in melt, the material melt the has purification. dopant to be concentration appropriately increases in the higher. crystal as well. Segregation Coefficient 0, 000008 0, 000025 0, 00003 0, 0004 0, 0007 0, 023 0, 07 0, 35 0, 8 1, 25 Fe Au Ni Cu N Sb C As P B O Segregation Coefficient: k = CLIQUID Resistivity [m cm] Concentration [1019 cm-3] concentration resistivity CSOLID = 3, 5 x 1018 cm-3 CLIQUID = 1, 0 x 1019 cm-3 C(p) = C 0(1 -p)k-1 p - normalized length (p = 1 for Lmax) k - segregation coefficient Silicon V 2. 3 En 20

Single Crystal Ingot Diameter: Dopant Boron: Phosphorus: Arsenic: Antimony: 100, 125, 150 mm Resistivity 0, 005 - 25 . cm 0, 0015 - 15 . cm 0, 003 - 0, 1 . cm 0, 015 - 0, 025 . cm for more specification: www. terosil. com Silicon V 2. 3 En 21

Chapter 2 Overview Introduction What is Inside an Electronic Device? Silicon - the Structure Silicon - Inside the Single Crystalline Defects Doping Silicon Wafer Silicon Obtaining Polycrystalline Silicon Czochralski Crystal Growth Czochralski Puller Crystal-Melt Interface Oxygen and Carbon in Silicon Crystal Segregation Coefficient Single Crystal Ingot Shaping and Testing Cropped Ingot Silicon V 2. 3 En Wafer Manufacturing Wafer Edge Grinding Double-Sided Lapping Stress Relief Etching Machine Backside Treatment CVD Equipment Polishing Machine Chemical Cleaning Inspection Scrubbing Final Inspection Epitaxy Epitaxial Reactor Epitaxial Layer Characteristics Appendix Clean Rooms Some Special Units 22

Ingot Shaping and Testing During The Crystallographic pulled crystal photograph the cropping ingot section of is orientation cut finished isofplaced into the crystal, individual silicon ofinthe thecylinder a single grinding few sections. thin crystal axis machine slices This iscylinder given are operation and removed by with theflat isseed for is called testing. machine orientation. on the cropping. next Usually grinds To identify slide. down resistivity Each the section a radial crystal profiles, iscrystallographic examided until oxygen the target and for defects. carbon orientation diameter Also, ofofthe the ends ofathe concentration cylinder crystal isflat reached. ingot isand ground are crystallographic removed. into it. Knowing defects the orientation, are tested. the Theposition set of slices of the flat allows is accurately to verify the determined variation of bymeasured X-ray diffraction. parameters. X-ray source Detector Silicon V 2. 3 En 23

Cropped Ingot Silicon V 2. 3 En 24

Chapter 3 Overview Introduction What is Inside an Electronic Device? Silicon - the Structure Silicon - Inside the Single Crystalline Defects Doping Silicon Wafer Silicon Obtaining Polycrystalline Silicon Czochralski Crystal Growth Czochralski Puller Crystal-Melt Interface Oxygen and Carbon in Silicon Crystal Segregation Coefficient Single Crystal Ingot Shaping and Testing Cropped Ingot Silicon V 2. 3 En Wafer Manufacturing Wafer Edge Grinding Double-Sided Lapping Stress Relief Etching Machine Backside Treatment CVD Equipment Polishing Machine Chemical Cleaning Inspection Scrubbing Final Inspection Epitaxy Epitaxial Reactor Epitaxial Layer Characteristics Appendix Clean Rooms Some Special Units 25

Wafer Manufacturing The damage When first saw cutting step is made comes in wafers the of production afrom thinthe astainless crystal, fact of silicon that itsteel issawing desired wafers withprocess afrom tohole a crystal in make is really the center. a flat aingot form cut. Aisof at nickel sawing. grinding. a specific matrix A The graphite angle with damage imbedded with beam respect exists is diamond attached to the crystal particles crystal wherever orientation isthe plated with blade an around and comes adhesive to waste the in inner contact toashold little edge with the material ofwafer thecrystal. blade. as after the saw This possible Therefore, diamond-nickel blade with theahas damaged minimum cutmatrix through material of provides damage thehas ingot. of ato surface the bewafers. removed which is used For in the that subsequent to the cut blade the silicon is steps. cooled ingot. Onand the rinsed enclosed by water video, with there surfactant. is a shot of sawing process. VIDEO 352 x 288 Water Stainless steel core Silicon Nickel matrix with imbedded diamond Damage particles Silicon V 2. 3 En 26

Wafer Edge Grinding Aftergrinding The wafer sawing, is placed wheel the wafers is ona vacuum disc havewith anchuck groove edgeand with of sharp corners. slowly desired turned "bulletas nose" The theedge grinding shape is ground ofwheel, wafertowhich edge. form a is There bullet rotating are embedded shaped at highedge. diamond speed, This isparticles forced increases against in edge the groove. the strength wafer edge. and make the edges less prone to chipping in later processing. High speed Low speed Silicon V 2. 3 En 27

Double-Sided Lapping Theabrasive During An next silicon lapping, step wafers slurry inwafers wafer in (aluminium carriers production are placed and oxide the is in called Al abottom O 3 and 2 carrier lapping. are suspended lapping driven plate Purpose between inare water visible of two this withcast step on surfactant) the iron is double tomade make is fed sided lapping wafer to the surface plates. wafers planetary The smooth, lapper carrier asflat video. they isand thinner are To parallel. see moved than thethe between wafersthe allowingplates. lapping movement both thesides upper This of removes lapping the wafer plate thetosilicon be is lifted lapped and for simultaneously. leaves demonstration. behind a. At more the end uniform of the surface. video there Wafers is are complete the very flat because machinethe during lapping the plates lappingare process. extremely flat. Lapping plate Slurry Carrier VIDEO 352 x 288 Wafer Gearing Lapping plate Silicon V 2. 3 En 28

Stress Relief Etching In both Since One Another The figure method lapping forms form below of of allows etching, shows only the used aalkaline to relative wafers remove on silicon and is the acid, bulk use of an wafers comparison there thealkaline are saw is acid advantages damage ofhydroxide, etching. the etch and Arates always common such disadvantages ofas a leaves potassium typical mixture a acid thin to uniform hydroxide used and choosing afor typical layer acid a(KOH). specific alkaline etching of damage, Inform. this is etch. HNO method, The some It 3 can table and other be the HF. on seen wafers the method are Sometimes, that bottom dipped theleft acid must side inadditional etch be KOH shows used continues andto chemicals awater comparison. remove tomixture etch the are silicon added for damage about to wafer The thepicture at mixture 2 minutes. afrom high of lapping. to arate chemical make The formixture This the as etching long reaction damage isas usually equipment the more needs two at to bekept elevated controllable. are and chemical removed in temperature contact. Inbath while anyiscase, Therefore causing on of the about thenext as acid the 100°C. little slide. acid etching Then etch additional the process must wafers be is controlled damage aare vigorous dipped very as process possible. into closely a DIwhich water to Typically, endneeds bath up to the chemical stop tight with an control anyacceptable remaining as etching it has wafer. reaction. is noused. self limiting properties. Alkaline K 2 Si. O 3 + 2 H 2 Si + H 2 O + 2 KOH Acid Etching 3 Si + 4 HNO 3 + 18 HF 3 H 2 Si. F 6 + 4 NO + 8 H 2 O Si + 4 HNO 3 + 6 HF H 2 Si. F 6 + 4 NO 2 + 4 H 2 O Acid Gives a surface that contains etch pits Gives a smooth surface Constant etch rates over life of bath Etch rate varies Self limiting, easy to control No self limiting, hard to control accurately Does not release EHS hazard Releases gases that must be scrubbed Silicon V 2. 3 En Alkaline Etching Acid ring nufactu fer Ma see Wa Alkaline 29

Etching Machine Silicon V 2. 3 En 30

Backside Treatment A batch For Silicon Polysilicon wafers dioxide of silicon that on the can are wafers backside be highly used indoped carrier prevents as a backseal. and prepared out are going The diffusing for deposition layer to go as is through well deposited is on as getters the a high on bottom the temperature heavy wafer picture. metals by You process, chemical from can see the abulk avapor chemical layer of deposition. the is deposited wafer. vapor deposition Normally The on oxide the back a acts silane side 4 of strictly (Si. H equipment ) source as theawafer on sealant. is the used tonext prevent for slide. polysilicon the dopant from out diffusing. deposition. Oxide Deposition Si. H 4 + O 2 420°C Polysilicon Deposition Si. H 4 620°C Silicon V 2. 3 En Si. O 2 + 2 H 2 Si + 2 H 2 31

CVD Equipment Silicon V 2. 3 En 32

Polishing The One A polishing purpose video of theshows polishing pad of wafer isthe mounted techniques wafers polishing on unloading the isistothe bottom produce template right plate. after a very The smooth, mounting soft polishing. insertflat, method. A is polishing necessary damage Thefree equipment wafers to hold silicon are theis surface. situated wafers shown. The in on inplace athe round polishing template when next slide. the attached step wafers is, are unlike onmounted a carrier lapping, to and atheset polishing on a soft chemical/mechanical polyurethane equipment with insert the surface inprocess. the template. facing Thisdown. difference The insert The bottom is has thea reason porous plate and polishing structure. carriersproduces When are rotating theawafer much around issmoother pressed their own against final axis. surface the water than soaked lapping. insert, it is held against it. Slurry for Silicon Polishing The polishing slurry consists of silica (silicon dioxide, Si. O 2) particles in aqueous suspension with an organic alkali and a surfactant. Wafer Carrier Slurry Insert Template Polishing pad Bottom plate Silicon V 2. 3 En 33

Polishing Machine Silicon V 2. 3 En 34

Chemical Cleaning At the After The most chemical the previous this time wafers cleaning, commonly of chemical cleaning steps have the method some used been wafer operation cleaning, method metals of polished, surface cleaning the ismay tocomplemented wafers is remove they still the freehave remain wafers of have aa large after thin particles on by contaminants, megasonic the native polishing number wafer is oxide the surface. of cleaning. is however SC 1 contaminants a layer wet (Standard The on cleaning small Megasonic top cleaning and amount on Clean consisting the agent waves 1) surface. contaminants ofsolution. particles for of are the In general, several are This metal acoustic may mostly mixture be contaminants chemical still these waves on present. istop contaminants the ofsteps. of very hot is thea. NH high The oxide mixture frequency first are or and of one embedded particles, HCl H 2 is O(about and a in hot organic water. H within O 2 init. 4 OH 2 21 residuals mixture Ammonium water. MHz). The role video The This ofofand sulfuric on waves the mixture hydroxide right metallic subsequent exert acid shows is known ions. under-etches and forces a hydrogen step, cleaning The ason. SC 2 chemical diluted particles line (Standard peroxide hydrofluoric and cleaning onawafer shot is designed called acid, attached Clean surface into the is 2). Piranha. to and megasonic to The etch the to help mixture remove out surface It to decomposes the cleaning detach oxidizes native them. andthem. eliminates bath. oxide virtually and reacts attractive any polishing with organics on theresiduals. slurry forces. metals wafer on Hydrogen thesurface silicon peroxide into carbon surface is and oxidizing dioxide removes agent and them. water. to grow thin clean oxide layer on the wafer surface, which makes it hydrophilic and prevents particles re -deposition. Particle Metallic ion Organic residual Native Si. O 2 VIDEO 352 x 288 H 2 SO 4 + H 2 O 2 (130°C) H 2 O + HF H 2 O + NH 4 OH + H 2 O 2 (70°C) H 2 O + HCl + H 2 O 2 (70°C) Silicon V 2. 3 En 35

Inspection After A The measurement total video the wafers indicator shows of thehave ofashape reading the non-contact been consistency deformation (TIR) polished automatic is aofmeasurement and of a wafer a cleaned, wafer is they isare warp. thickness that inspection Warp only ready isline. concerned is total the to thickness be measure inspected. with variation the of maximum front During side (TTV). the difference of It a is inspection between the wafer. difference The the process, way highest between this the measurement and the resistivity lowest maximum location and is made and geometrical of is theby parameters centerline minimum reference thickness to ofare aa plane wafer measured ofthat with a wafer. is respect by parallel non-contact totoreference the vacuum methods. plane chuck defined that the by wafer three is pedestals mounted on. near The the. TIR wafer is the edge. difference between the height of the highest peak and the deepest valley on the front of the wafer. VIDEO 352 x 288 Wafer centerline Tmax Dmax hmax Tminh Dmin Wafer min Reference plane Vacuum chuck Warp TTV TIR==(D T hmax T hmin max -- D min) / 2 Silicon V 2. 3 En 36

Scrubbing Wafer The During wafers scrubbing the scrubbing are cleaned with aqueous theto. PVA remove brush ammonium particles is very and metal contamination hydroxide effective for (NH particle removal. but after across After inspection the DIwafer water may surface rinse have 4 OH) flows anremove to and increased drying the wafers number particles. are of prepared Simultaneously particlesfor onfinal the inspection surface again. brushing and packaging. The is scrubbing made by polyvinil has to be alcohol used for (PVA) finalfibers mechanical/chemical which Both the do scrubbing not scratchand the cleaning. the wafer subsequent when brought final into direct contact inspection arewith realized the wafer in clean surface. rooms of class 10. The video on right shows a scrubbing operation. Silicon V 2. 3 En VIDEO 352 x 288 37

Final Inspection Wafer Diameter: TTV: TIR: WARP: 100, 125, 150 mm < 5 µm < 4 µm < 30 µm (typical for 100 mm wafers) Particles >0, 5 µm Metal Contamination: <5 3 x 1010 atoms/cm 2 for more specification: www. terosil. com Silicon V 2. 3 En 38

Chapter 4 Overview Introduction What is Inside an Electronic Device? Silicon - the Structure Silicon - Inside the Single Crystalline Defects Doping Silicon Wafer Silicon Obtaining Polycrystalline Silicon Czochralski Crystal Growth Czochralski Puller Crystal-Melt Interface Oxygen and Carbon in Silicon Crystal Segregation Coefficient Single Crystal Ingot Shaping and Testing Cropped Ingot Silicon V 2. 3 En Wafer Manufacturing Wafer Edge Grinding Double-Sided Lapping Stress Relief Etching Machine Backside Treatment CVD Equipment Polishing Machine Chemical Cleaning Inspection Scrubbing Final Inspection Epitaxy Epitaxial Reactor Epitaxial Layer Characteristics Appendix Clean Rooms Some Special Units 39

Epitaxy For Epitaxy The After If there particular process result theare issurface the ofany proceeds the applications growth phosphine process etching ofatthe is is high there (PH finished, from silicon temperature a molecules a layer few the need toon trichlorosilane tens toabout the present, form silicon 1200 a 3)is layer wafer °C. (Si. HCl the micrometers phosphorus Hydrogen of surface. vapors resistivity thick flows The are atoms epitaxial layer past introduced. material dope has thelayer. the incandescent theon Si. HCl growing same top 3 of crystallographic reacts lower epitaxial silicon withlayer. 3)high resistivity properties wafers. present Boron On thecompounds enclosed When hydrogen material. as the hydrogen video, substrate, atcan The a high be there epitaxial chloride used temperature. but areitfor growth is the can doping added, shots have is. The used as itof astarts different result well. thefor this of purpose. dopant reacting this wafers reaction loading concentration with are silicon onfree a and susceptor silicon or even it etches atoms different andthe that their wafer dopant. settle unloading. surface on the away. silicon You can Itwafer isalso important surface see theto following control remove board its allcrystal the of contaminants anlattice epitaxial or surface defects of the silicon structure. reactor. H H Cl Cl Si H H H Cl H P H H Silicon V 2. 3 En H Cl H H Cl Cl Si H Cl Si Si Si P Si Si H VIDEO 320 x 240 H Cl Si H H Cl 40

Epitaxial Reactor N 2 HCl Si. HCl 3 PH 3 At this extremely Epitaxial During the reactor process, is high an the temperature, equipment chamber with forthe the process growth wafersofis the epitaxial flushed proceeds with in the nitrogen layer. way Silicon described and hydrogen. wafers onare the. Inloaded slide the Epitaxy. on a graphite hydrogen The susceptor block environment -with susceptor. wafers the is susceptor The cooled susceptor down with wafers is then placed and is insidenitrogen warmed after a quartz up byflushing the glass induction bell-shaped it is taken heating out chamber. from at thethe. Around the chamber, ofthere temperature chamber. about is 1200°C. an induction heating coil. B 2 H 6 gas exhaust Silicon V 2. 3 En 41

Epitaxial Layer Characteristics Wafer Diameter: Epi Layer Thickness: Epi Layer Resistivity: 100, 150 mm 3 - 50 µm 3 - 50 cm for more specification: www. terosil. com Silicon V 2. 3 En 42

Chapter 5 Overview Introduction What is Inside an Electronic Device? Silicon - the Structure Silicon - Inside the Single Crystalline Defects Doping Silicon Wafer Silicon Obtaining Polycrystalline Silicon Czochralski Crystal Growth Czochralski Puller Crystal-Melt Interface Oxygen and Carbon in Silicon Crystal Segregation Coefficient Single Crystal Ingot Shaping and Testing Cropped Ingot Silicon V 2. 3 En Wafer Manufacturing Wafer Edge Grinding Double-Sided Lapping Stress Relief Etching Machine Backside Treatment CVD Equipment Polishing Machine Chemical Cleaning Inspection Scrubbing Final Inspection Epitaxy Epitaxial Reactor Epitaxial Layer Characteristics Appendix Clean Rooms Some Special Units 43