Agenda. 1. Atomic Layer Deposition Technology

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1 Agenda 1. Atomic Layer Deposition Technology 2.

2 What is ALD? Atomic Layer Deposition is invented in 1977 by T. Suntola et al. - New Deposition Method for Electro-Luminescent Display (ZnS:Mn Thin Films) - US Patent No. 4,058,430 (1977) Atomic Layer Deposition is the Method where the Source Materials are alternately pulsed in the Reactor Chamber and on to the Substrate - Mono-layer Deposition of the Target Materials Atomic Layer Deposition (A.L.D.) is called by in Korea - A.L.E.(Atomic Layer Epitaxy), ALCVD(Atomic Layer C.V.D.), Cyclic CVD, Sequential CVD, etc. World s Best People, World s Best Products, World s Best Company. 2/49

ALD Mechanism Chemical Vapor Deposition is the Method where a Mixture of Gases flows over a Heated Substrate causing a Thin solid Film to Grow on the Substrate Continuous Growth by Mixture of Gas

3 ALD Mechanism Chemical Vapor Deposition is the Method where a Mixture of Gases flows over a Heated Substrate causing a Thin solid Film to Grow on the Substrate Continuous Growth by Mixture of Gas Flows Absorption Desorption Surface diffusion Surface reaction Co-exposure Co-exposure of of source source and and reactants reactants Absorption Absorption and and surface surface migration migration of of source source and and reactants reactants Chemical Chemical reaction reaction takes takes place place with with help help of of thermal thermal energy energy (or (or plasma plasma enhancement, enhancement, ) ) Desorption Desorption of of by-products by-products World s Best People, World s Best Products, World s Best Company. 3/49

4 ALD Mechanism Atomic Layer Deposition is the Method where the Source Materials are alternately pulsed in the Reactor Chamber and on to the Substrate - One Atomic Layer or Monolayer in One Reaction Cycle A Feeding A Purge B Feeding B Purge 1 Cycle A A Feeding Feeding Step Step : : Reactant Reactant A A Chemisorption Chemisorption A A Purge Purge Step Step : : Purge Purge out out Excess Excess Reactant Reactant A A & Side Side Product Product B B Feeding Feeding Step Step : : Reactant Reactant B B Chemisorption Chemisorption & Exchange Exchange Reaction Reaction B B Purge Purge Step Step : : Purge Purge out out Excess Excess Reactant Reactant B B & Side Side Product Product World s Best People, World s Best Products, World s Best Company. 4/49

5 ALD Mechanism Atomic Layer Deposition Flow Rate A Purge B Purge 1 Cycle 1 Cycle 1 Cycle 1 Cycle 1 Cycle 1 Cycle Time ALD is based on the Sequential Deposition of Individual Mono-layer by Alternate Gas Supply World s Best People, World s Best Products, World s Best Company. 5/49

6 ALD Mechanism Self-limiting Reaction is not Gas-Gas Interaction but Gas-surface Interactions Itself (ie. Ligand Exchange Dissociation, Association). Gas-surface Interface Reaction self-saturates when All Gas are converted to New Surface. New Surface cannot further react with the exposing Gas - Self-limiting reaction is the basic of ALD Process Ligand Exchange Dissociation Association World s Best People, World s Best Products, World s Best Company. 6/49

7 ALD Mechanism Surface Saturation defined by a. Ideal ALD : A monolayer after 1 Cycle may be a Full Monolayer + - b. Real ALD : A monolayer after 1 Cycle may be a Partial Monolayer(< Full Monolayer) due to Steric Hinderance of Ligand or/and Number of Bonding Sites + - World s Best People, World s Best Products, World s Best Company. 7/49

8 ALD Process Parameter ALD Process Temperature Deposition Rate Additive Gas (or Reactant Gas) Reaction Temperature Thermal Decomposition Temperature Desorption Condensation Limit Temperature Process Window for ALD Source Temperature (Vapor Pressure) Process Window For Layer by Layer & General CVD The Most Important Parameter to Control the Mechanism of an ALD Process is the Processing Temperature World s Best People, World s Best Products, World s Best Company. 8/49

9 ALD Process Parameter Source Flow Rate & Time Deposition Rate (/cycle) Source Flow Rate (sccm) - Source Flow Rate Half-reaction Saturation for Source Flow Rate > 120 sccm Saturation - Source Feeding Time Deposition Rate (/cycle) Half-reaction Saturation for Source Feeding Time > 1.3sec Saturation Source Feeding Time (sec.) ALD Reaction are carried out in an Effective Overdosing Condition for a Complete Saturation of the Surface Reaction World s Best People, World s Best Products, World s Best Company. 9/49

10 ALD Process Parameter Purge Flow Rate & Time Deposition Rate (/cycle) Purge Flow Rate Saturation Purge Flow Rate (sccm) No Mixture between Sources for Purge Flow Rate > 120 sccm - Purge Time Deposition Rate (/cycle) No Mixture between Sources for Purge Time > 1.3sec Saturation Purge Time (sec.) Parasitic CVD is suppressed by Sufficient Purge Flow Rate & Time between A Source and B Source World s Best People, World s Best Products, World s Best Company. 10/49

11 ALD Process Parameter ALD Process Guidelines Supply Reactants separately in Chamber for ALD Process Self-limiting Surface Reactions or Adsorption must be the Dominant Processes. Carry out Each Process Steps in Temperature Windows of ALD Processing Carry out in an Sufficient Source Flow Rate & Time Condition for a Complete Saturation of the Surface Reaction Suppress Parasitic CVD by Sufficient Purge Flow Rate & Time Avoid Usage of Unstable Molecular World s Best People, World s Best Products, World s Best Company. 11/49

ALD Characteristic Simple & Precise Thickness Control SiO 2 Film Thickness [ ] 200 160 120 80 40 Native Native Oxide: Oxide: 7.6 7.6 Dep. Dep. Rate: Rate: 1.60/cycle 1.

12 ALD Characteristic Simple & Precise Thickness Control SiO 2 Film Thickness [ ] Native Native Oxide: Oxide: Dep. Dep. Rate: Rate: 1.60/cycle 1.60/cycle Poly-Si Al 2 O 3 Si SiO 2 Deposition Cycle (source : IEDM 2000, D. Buchanan) - Deposition Thickness Linear with number Reaction Cycles (Total Thickness : Growth Rate Number of Cycle) - Precise Control in Very Thin Thickness of only 10 ~ 50 World s Best People, World s Best Products, World s Best Company. 12/49

13 ALD Characteristic Excellent Step Coverage Top of Cap. 30nm Deep Trench Capacitor Bottom of Cap. ULT ALD SiO 2 29nm Aspect Ratio : 60:1 ( Height : 8,000nm / Width : 165nm ) ULT ALD SiO 2 Film Thickness - Top of Cap. : 30nm - Middle of Cap. : 29nm - Bottom of Cap. : 29.5nm Step Coverage : > 98% ULT ALD SiO 2 ULT ALD SiO 2 performs extremely High Step Coverage in a deep Contact Hole 29.5nm compare to CVD SiO 2 World s Best People, World s Best Products, World s Best Company. 13/49

14 ALD Characteristic Excellent Uniformity & Extendibility Film Thickness () Thickness () W/W Uniformity : < 3% WTW Uniformity : < 2% BTB Uniformity : < 2% 6 4 Uniformity (%) Wafer Number Repeatable Process with Excellent Thickness Uniformity (WIW <3%, WTW <2%) World s Best People, World s Best Products, World s Best Company. 14/49

15 ALD Characteristic Low Process Temperature Arb. Dep. Rate ALD Region ALD + CVD Region CVD Region Arb. Temp. Unit ALD Process Temp. < ALD + CVD Process Temp. < CVD Process Temp. The Temperature of ALD Oxide Process is about 200 ~ 400 World s Best People, World s Best Products, World s Best Company. 15/49

ALD Characteristic Excellent Film Quality Cl Content [%] 10 8 6 4 2 Cl Contents Resistivity ALD TiN CVD TiN 800 600 400 200 Resistivity [ [.

16 ALD Characteristic Excellent Film Quality Cl Content [%] Cl Contents Resistivity ALD TiN CVD TiN Resistivity [ [.] Atomic Contents [%] C Cl O2 N Ti Si Wafer Temperature ()( Sputtering Time (s) ALD TiN has Low Resistivity due to Low Cl Concentration. The Ratio of Ti to N was 1:1 ( Stoichiometric TiN Film ) World s Best People, World s Best Products, World s Best Company. 16/49

ALD Characteristic Materials Engineering (

Properties at Interfaces and Bulk World s Best

17 ALD Characteristic Materials Engineering ( Nano-laminate and Stack ) (source : ALD 2001, Ofer Sneh) Improve Physical and Electronic Properties Independent Adjustment of Film Properties at Interfaces and Bulk World s Best People, World s Best Products, World s Best Company. 17/49

18 ALD Characteristic Excellent Particle Performance 100 Particle Size : > In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning Particle ( # ) 50 In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning In-Situ Cleaning Wafer Numbers Clean, Stable Process with Excellent Particle Performance ( <15 adders for 0.16um ) World s Best People, World s Best Products, World s Best Company. 18/49

19 ALD Characteristic Criteria ALD CVD PVD Thickness Range < 200 > 100 > 200 Uniformity Control Range 10 Range 50 Range Film Quality - Excellent Stoichiometry - Low Pinhole Count - Stress Control Possible - Excellent Stoichiometry - Low Pinhole Count - Stress Control Possible - Limited Stoichiometry - High Pinhole - Limited Stress Control Possible Conformality 100% Step Coverage in 60:1 AR 100% Step Coverage in 10:1 AR, but Step Coverage not assured 50% Step Coverage in 10:1 AR Cleanliness No Particles due to Gas Phase Reactions Particles due to Gas Phase Reaction Particles due to Sputtering Process Window < 1% Dependency on 10% Process Parameter Changes Strong Dependency on Process Parameter Changes Very Dependent on Vacuum Integrity Scalability Nearly Transparent from 200 ~ 300mm regarding Process Results Major Parameter Changes needed for same process Results from 200 ~ 300mm Major Throughput Hit when going to from 200 ~ 300mm Extendibility No Limits 90 ~ 65nm Technology 100nm Technology Throughput Very Poor Fair Good World s Best People, World s Best Products, World s Best Company. 19/49

20 ALD Characteristic ALD Characteristic Summary Simple & Precise Thickness Controllability Excellent Thickness Uniformity for 300mm Wafer Excellent Step Coverage in Conformal Structure with High A/R Low Thermal Budget due to Low Process Temperature Excellent Film Quality Material Engineering for Improving Physical & Electronic Properties Low Particle Generation Low Throughput due to Low Deposition Rate World s Best People, World s Best Products, World s Best Company. 20/49

21 ALD Apparatus Examples of CVD Type ALD Apparatus Shower Head 4 1. Reaction Chamber Susceptor & Heater 3. Substrate 4. Shower Head for Uniform Source Supply Advantage - Excellent Uniformity due to Uniform Source Flow Disadvantage - Low Material Utilization Efficiency due to Large Reaction Volume - Long Purge Time due to Low Conductance of S/H World s Best People, World s Best Products, World s Best Company. 21/49

22 ALD Precursor Major Requirement of ALD Precursor Volatility - Preferably Liquids and Gases - Approximate Vapor Pressure Requirement : 0.1 torr Aggressive and Complete Reactions - Short Cycle Time due to Fast Saturation - High Film Purity due to Complete Reaction - No Problems of Gas Phase Reactions No Self-Decomposition - Source Decomposition would destroy the Self-limiting Film Growth (Thickness Non-uniformity and Inaccuracy) - Source Decomposition may cause Contamination World s Best People, World s Best Products, World s Best Company. 22/49

23 ALD Precursor Major Requirement of ALD Precursor Requirements No Etching of the Film or Substrate Material - Etching would prevent the Film Growth No Dissolution into the Film Substrate Sufficient Purities Minor Requirement of ALD Precursor Requirements Unreactive Volatile By-products In Expensive Easy to Synthesize and Handle Non-toxic and Environmentally Friendly World s Best People, World s Best Products, World s Best Company. 23/49

ALD Precursor Examples of Metal Precursors Halides - Applicable Precursor in ALD Oxide, Sulfide, Nitride Films - Volatile and Reactive enough but most of them are Solids - Maximum Surface Coverage :

24 ALD Precursor Examples of Metal Precursors Halides - Applicable Precursor in ALD Oxide, Sulfide, Nitride Films - Volatile and Reactive enough but most of them are Solids - Maximum Surface Coverage : 1/3 ~ 1/2 (due to the size of the chloride anions and repulsion) Metal Non-Metal Film AlCl3 H2O, H2O2, O2 Al2O3 GaCl3 AsH3 GaAs SiCl4 H2O SiO2 TiCl4 NH3 TiN ZrCl4 H2O ZrO2 HfCl4 TaCl5 H2O H2O HfO2 Ta2O5 Halides World s Best People, World s Best Products, World s Best Company. 24/49

25 ALD Precursor Examples of Metal Precursors Organometallic - Alkyl, Alkoxide, -diketonato, Cyclopentadienyl, Carboxylato Compound etc. - Widely used in the CVD & MBE method. ( Especially - Semiconductor ) - Gas or Liquid so that Vapor Pressure is higher than that of Halides - In-film Impurities could be a Concern (C, H, N etc.) Metal Non-Metal Film Al(CH3)3 H2O, H2O2, O3 Al2O3 Ga(CH3)3 AsH3 GaAs In(CH3)3 AsH3 InAs Ta(OC2H5)5 H2O Ta2O5 La(thd)3 H2O, O3 La2O3 ZrCp2Cl2 O3 ZrO2 Zn(CH3COO)2 H2O ZnO2 Cyclopentadienyle World s Best People, World s Best Products, World s Best Company. 25/49

26 ALD Precursor Examples of Non-Metal Precursors Oxygen Source - Water(H2O) has been by far the mostly used precursor for oxygen source Water reacts fast with many metal halides & alkyls - The use of ozone makes the ALD oxide from the Alkyls & -diketonates faster (TMA + O3 Al2O3, La(thd)3 + O3 La2O3) Nitrogen Source - NH3 has been the by far the mostly used precursor for ALD Nitride - Three type of approaches have been take toward ALD nitride a. Epitaxial GaN from alkyls & NH3 for opto-electronics b. Polycrystalline AlN for dielectric & passivation layer c. Polycrystalline transition metal nitride (TiN, TaN, Ta3N5, MoN) from metal chloride for diffusion barrier & protective layer World s Best People, World s Best Products, World s Best Company. 26/49

27 ALD Application in Semiconductor Motivation for Device Down-Scaling Higher Speed Higher Device Density (& Functionality) Year of Production DRAM Half-pitch (nm) MPU Gate Length (nm) (Source : 2001 ITRS) Device Down Scaling Issues : Shorter Channel Length Shallow Junctions Thinner Gate Oxides Faster Interconnects (RC) World s Best People, World s Best Products, World s Best Company. 27/49

ALD Application in Semiconductor Semiconductor Processing Requirements Excellent Thickness Controllability Simple Process with Low Particle Generation Good Uniformity for 300mm Wafer Excellent Step

28 ALD Application in Semiconductor Semiconductor Processing Requirements Excellent Thickness Controllability Simple Process with Low Particle Generation Good Uniformity for 300mm Wafer Excellent Step Coverage Low Thermal Budget Capability to form the Layered Structure to Improve Physical & Electronic Properties Solution A.L.D Technology World s Best People, World s Best Products, World s Best Company. 28/49

29 ALD Application in Semiconductor ALD Application Cu Barrier W Nucleation Gate Dielectric Gate Spacer Cap. Dielectric Electrode Barrier World s Best People, World s Best Products, World s Best Company. 29/49

30 ALD Application Gate Dielectric Scaling of Gate Oxides Poly-Si Gate Leakage due to Tunnel Current Boron Penetration in p-mosfet - Threshold Voltage Shift Source Drain - Reliability Degradation of Gate Oxide Year of Production Gate Oxide HP EOT (nm) 1.3 ~ ~ ~ ~ ~ 1.3 HP LKG (A/) ~ ~ (source : 2001 ITRS) World s Best People, World s Best Products, World s Best Company. 30/49

31 ALD Application Gate Dielectric Why is ALD High-k for Gate Dielectric? Teq of the Gate Stack less than 1.0nm High Dielectric Constant (> ~10) Low Leakage Current (less than 1A/) Large Band Gap & Barrier Height High Thermal Stability, Interdiffusion Low Thermal Budget, Defect-free Process Ta2O5, TiO2, Al2O3, ZrO2, HfO2, BST HfO2, Al2O3, Laminate World s Best People, World s Best Products, World s Best Company. 31/49

32 ALD Application Gate Spacer Issue of High Thermal Budget in Sub-Micro Device SiO 2 Spacer Poly-Si SiN Spacer Source L Drain : Thermal Diffusion of Dopant : Gate Channel Length (L) (source : J.H. Yang, VLSI 2003) In Case of Conventional SiO 2 & SiN as Gate Spacer in Sub90nm Device, High Thermal Budget deteriorate Short Channel Characteristics ALD Process is Attractive Method for Low Thermal Budget World s Best People, World s Best Products, World s Best Company. 32/49

33 ALD Application Gate Spacer SiN Development Trend < 600 < 500 DCS + NH3 DCS + NH3 BTBAS + NH3 Atomic Layer Deposition SiO2 Development Trend < 400 SiH4 + N2O SiH4 + N2O Single CVD SiO2 Atomic Layer Deposition 0.25um 0.18um 0.13um > 0.09um Gate Length World s Best People, World s Best Products, World s Best Company. 33/49

34 ALD Application Capacitor Dielectric Requirements to the Future Capacitor Dielectric Excellent Step Coverage in Very High Aspect Ratio Structure High Dielectric Constant (>10) Easy & Accurate Thickness Control Large Band Gap & Barrier Height Low Leakage Current (less than 1A/) High Thermal Stability, Inter-diffusion SiO2 Si3N4 Al2O3 ZrO2 HfO2 Ta2O5 TiO2 SrTiO3 k ~10 ~22 ~25 ~25 ~80 ~200 Low Dielectric World s Best People, World s Best Products, World s Best Company. 34/49 Promising Low Band Gap

35 ALD Application Cu Barrier Cu Interconnect Lower Resistivity (1.7) Better EM Resistance IMD Cu Better Thermal Expansion Property But, Cu is Fast Diffuser and IMD Causes Deep-level Trapping Etch Stop IMD Cu Diffusion Barriers in <100nm should : Barrier Separate Inter metal dielectric & Cu Be Conductive Be Thin (<100) & Conformal (2.4 ~ 3.0) ALD ALD TaN TaNor or TiN TiNis is a Promising Promising Technique Technique World s Best People, World s Best Products, World s Best Company. 35/49

ALD Application in Semiconductor ALD Market Forecast $ Millions 2001-2008 CAGR est. 29.

36 ALD Application in Semiconductor ALD Market Forecast $ Millions CAGR est. 29.5% (source : 2001 VLSI) Annual Growth Rate for ALD between 2001 and 2008 will reach 29.5% World s Best People, World s Best Products, World s Best Company. 36/49

37 What is Solution for Throughput? ALD Advantage Simple & Precise Thickness Controllability Excellent Thickness Uniformity for 300mm Wafer Excellent Step Coverage in Conformal Structure with High A/R Low Thermal Budget due to Low Process Temperature Excellent Film Quality Low Particle Generation Low Throughput due to Low Deposition Rate What is is Solutions for for Throughput? World s Best People, World s Best Products, World s Best Company. 37/49

38 What is Solution for Throughput? ALD Solution to Increase Throughput Process Development Mixture of ALD & CVD Process New Precursor Development ( High Reactivity, High Dep. Rate, High Vapor Pressure etc. ) PEALD Process Development using Plasma Hardware Development Multi-Wafer ALD System Development World s Best People, World s Best Products, World s Best Company. 38/49

39 What is Solution for Throughput? Mixture of ALD & CVD Process ALD Temperature < ALD + CVD Temperature < CVD Temperature No Purge Between A source Feeding and B source Cycle Time Reduction, ALD & CVD Reaction 3.0 Flow Rate Arb. Dep. Rate ALD Region ALD + CVD Region Arb. Temp. Unit CVD Region Disadvantage : Smaller ALD Process Flexibility Time Degradation of Film Quality due to high impurity World s Best People, World s Best Products, World s Best Company. 39/49

than Pure ALD To increase Choice of Chemistry or Reactant Disadvantage : Damage of Chamber or Film

40 What is Solution for Throughput? PEALD Process using Plasma Cycle Time of PEALD lower than Pure ALD Deposition Rate of PEALD higher than Pure ALD To increase Choice of Chemistry or Reactant Disadvantage : Damage of Chamber or Film by Plasma (Source : 2002 ALD Conference, E. S. Choi) Problem of Step Coverage due to Plasma Life Time World s Best People, World s Best Products, World s Best Company. 40/49

41 What is Solution for Throughput? Multi-Wafer ALD System - Furnace Advantage - Throughput of Furnace Type ALD System higher than Single ALD System Disadvantage - Cross Contamination of Substrates in Batch Reactor & Batch to Batch - Difficult to prevent Back-side Dep. - Less Flexible than Single ALD System Process Capability : 25 ~ 100 wafers / 1 Batch for Process Control, Process Variation, and Maintenance World s Best People, World s Best Products, World s Best Company. 41/49

42 Summary ALD offers Several Advantages over Conventional Deposition Process! : Step Coverage, Uniformity, Film thickness Film Control & Film Quality ALD has a Number of Application in Sub 100nm Device! : High-k Dielectrics, Metal Electrodes, Barriers &. Spacers Major Issue for ALD is Throughput due to Low Deposition Rate! Equipment & Device Company are developing Solutions to improve Low Throughput! : Source Development, PEALD, Batch Type System ALD has a Bright Future in Semiconductor Processing!!! World s Best People, World s Best Products, World s Best Company. 42/49

43 Agenda 1. Atomic Layer Deposition Technology 2.

44 Value Chain IT World s Best People, World s Best Products, World s Best Company. 44/49

45 LSI Market Share (%) World s Best People, World s Best Products, World s Best Company. 45/49

46 World s Best People, World s Best Products, World s Best Company. 46/49

47 H D O D O N L 2006 R a n k C o m I n t e l S a m s u n g E l e c t r o n i c s T e x a s I n s t r u m e n t s I n f i n e o n T e c h n o l o g i e s S T M T o s h i b a y n i x S e m i c o n d u c t o r R e n e s a s A d v a n c e d M e v i c e s F r e e s c a l e S e m i c o n d u c t o r t h e r s T o t a l M p a n y i c r o e l e c t r o n i c s T e c h n o l o g y a r k e t <Semiconductor> i c r o Source: Gartner Dataquest (April 2007) 2006 R e v e n u e 30, , , , 533 9, 854 9, 783 8, 007 7, 900 7, 434 6, , , 690 Millions of U.S. Dollars 2006 M a r k e t S h a r e ( % ) R a n k <Semiconductor E q uip ment> C o m A p p l i e d M T o k y o A S M K L A -T e n c o r L a m R e s e a r c h A d v a n t e s t i k o n N o v e l l u s S y s t e m s C a n o n t h e r s T o t a l M p a n y a i n i p p o n S c r e e n E l e c t r o n a r k e t a t e r i a l s 2006 R e v e n u e 6, , , , , , , , , , M a r k e t S h a r e ( % ) Source: Gartner Dataquest (April 2007) Millions of U.S. Dollars World s Best People, World s Best Products, World s Best Company. 47/49

48 100.0% Thousands of U.S. Dollars 6,000,000 5,311,204 5,131, % 78.0% 82.3% 81.1% 60.0% 3,666,441 4,000, % 2,000, % 22.0% 17.7% 18.9% 0.0% World s Best People, World s Best Products, World s Best Company. 48/49

49 World s Best People, World s Best Products, World s Best Company. 49/49

CVD: General considerations.

CVD: General considerations. PVD: Move material from bulk to thin film form. Limited primarily to metals or simple materials. Limited by thermal stability/vapor pressure considerations. Typically requires