Presentation is loading. Please wait.

Presentation is loading. Please wait.

Semitool Confidential 1 Copper Damascene Plating 1/5/06 Brandon Brooks Process Development Engineer.

Similar presentations


Presentation on theme: "Semitool Confidential 1 Copper Damascene Plating 1/5/06 Brandon Brooks Process Development Engineer."— Presentation transcript:

1 Semitool Confidential 1 Copper Damascene Plating 1/5/06 Brandon Brooks Process Development Engineer

2 Semitool Confidential 2 Outline Why Cu Interconnects? Damascene Process Flow Parameters Affecting Cu Interconnects Backside Clean and Bevel Etch

3 Semitool Confidential 3 Damascene Plating?

4 Semitool Confidential 4 Why Cu Interconnects? AlCuW Melting Pt (°C) 6601,0833,410 Oxidation in AirRapid; Self-SealingSlow; Not Self-SealingInert Resistivity (m  -cm) Crystalline As Deposited * Self-Diffusion Coefficient (cm 2 s °C 2.1· · Coefficient of Thermal Expansion (Unit/°C) 24· · ·10 -6 * Alloy (Si, Cu)  Resistivity  Melting Point  Thermal Expansion  Electromigration Al  Resistivity  Melting Point  Thermal Expansion  Electromigration Cu Best! Interconnect Metal Properties

5 Semitool Confidential 5 Why Cu Interconnects? AlCuAg Etch Properties Cl & Br Plasmas F & Cl Plasmas Etch Rate (Å/min) 5, ,000 Cu has a very slow etch rate Cu halides are solid at normal temperatures Changing from Al to Cu interconnects requires new process flow Enter Damascene plating Interconnect Metal Properties

6 Semitool Confidential 6 Damascene Process Flow Typical Damascene Process Flow 1.Dielectric Deposition 2.Photoresist Deposition 3.UV Exposure 4.Develop Photoresist 5.Etch Dielectric 6.Remove Photoresist 7.Barrier Deposition 8.Seed Layer Deposition 9.Electrochemical Deposition (ECD) 10.Backside Clean and Bevel Etch 11.Anneal 12.Chemical Mechanical Polish (CMP) 13.Repeat Steps 1-10 for Every Metal Layer Today’s Main Topics

7 Semitool Confidential 7 Damascene Process Flow

8 Semitool Confidential 8 Copper Interconnect Parameters Key Factors Affecting Cu Interconnect Performance 1.Gap-Fill 2.CD Uniformity 3.Overburden 4.Anneal AMD’s 9 Cu Levels

9 Semitool Confidential 9 Copper Interconnect Parameters: Gap-Fill Key Parameters for Gap-Fill 1.Seed and Barrier Layers 1.Uniformity 2.Thickness 2.Plating Recipe 1.Hot Start (Initiation) 2.Fill Current Density 3.Waveform 3.Plating Chemistry 1.Inorganic 2.Organic 0.12  m, 8.3:1AR Trenches

10 Semitool Confidential 10 Copper Interconnect Parameters: Gap-Fill Physical Vapor Deposition (PVD) Effects Seed and Barrier Layers

11 Semitool Confidential 11 Edge ShadowingOptimized Seed Layer Copper Interconnect Parameters: Gap-Fill Seed and Barrier Layer Uniformity

12 Semitool Confidential Å Total Seed Thickness2000Å Total Seed Thickness 0.30micron, 4.8:1 AR Vias Copper Interconnect Parameters: Gap-Fill Seed and Barrier Layer Thickness

13 Semitool Confidential 13 Copper Interconnect Parameters: Gap-Fill Plating Recipe Hot Start  m Line Width Trenches 48 Coulombs ECD No Hot Start 2V Hot Start 2X Fill Rate on the 2V Hot Start

14 Semitool Confidential 14 Copper Interconnect Parameters: Gap-Fill Plating Recipe Current Density Current too Low Current too High The Effect of Current Density upon Gap Fill Bad Good 0.35μm, 4.3:1 AR Vias 0.18μm, 5.1:1 AR Trench Gap Fill Current Density LowHigh Optimum Fill for feature D Optimum Current

15 Semitool Confidential 15 Copper Interconnect Parameters: Gap-Fill Plating Recipe Waveform WaveformCu DiffusionAdditive AdsorptionBottom Up Fill Direct Current (DC)-+0 Pulse DC+-0 Pulse Reverse (PR)+-0 DC plating provides better additive adsorption Pulsed plating provides better Cu diffusion

16 Semitool Confidential 16 Copper Interconnect Parameters: Gap-Fill Plating Chemistry Inorganic Components 1.Copper Sulfate (CuSO 4 ) 2.Hydrochloric Acid (HCl) 3.Sulfuric Acid (H 2 SO 4 ) Organic Components 1.Suppressor (PEG) 2.Accelerator (SPS) 3.Leveler (Amine)

17 Semitool Confidential 17 Copper Interconnect Parameters: Gap-Fill Inorganic Plating Chemistry Copper Effect on Gap Fill High Copper Low Copper

18 Semitool Confidential 18 Inorganic Plating Chemistry Copper Interconnect Parameters: Gap-Fill Chloride Effect on Gap-Fill

19 Semitool Confidential 19 Copper Interconnect Parameters: Gap-Fill Inorganic Plating Chemistry pH 3 pH 2 Acid Effect on Gap Fill pH 2

20 Semitool Confidential 20 Accelerator –Catalytic effect –Requires very small amount of Cl - –Increased current for a given potential Suppressor –Suppresses deposition –Requires Cl - to adsorb onto copper surface –Decreases current for a given potential Leveler –Suppresses deposition at high current density areas –Very low concentration (diffusion limited) Copper Interconnect Parameters: Gap-Fill Organic Plating Chemistry Organic Effect on Gap Fill

21 Semitool Confidential 21 A C B A = VMS B = VMS + Suppressor C = VMS + Sup. & Accel. I V Cyclic Voltammetric Stripping Analysis (CVS) Copper Interconnect Parameters: Gap-Fill Organic Plating Chemistry Plating Region Stripping Region

22 Semitool Confidential 22 Copper Interconnect Parameters: Gap-Fill Organic Plating Chemistry

23 Semitool Confidential 23 Copper Interconnect Parameters: Gap-Fill Organic Plating Chemistry

24 Semitool Confidential 24 Organic Plating Chemistry Copper Interconnect Parameters: Gap-Fill

25 Semitool Confidential 25 Organic Plating Chemistry Copper Interconnect Parameters: Gap-Fill

26 Semitool Confidential 26 Organic Plating Chemistry Copper Interconnect Parameters: Gap-Fill

27 Semitool Confidential 27 Organic Plating Chemistry Copper Interconnect Parameters: Gap-Fill

28 Semitool Confidential 28 Organic Plating Chemistry Copper Interconnect Parameters: Gap-Fill

29 Semitool Confidential 29 Key Parameters for Current Density Uniformity 1.Chemistry 1.High Acid 2.Low Acid 2.CFD Reactor 1.Electric Field Control Intel: 8 Cu Levels Copper Interconnect Parameters: CD Uniformity

30 Semitool Confidential 30 Copper Interconnect Parameters: CD Uniformity + Cathode (Reduction) Current Path Anode (Oxidation) Cu 2+ +2e -  Cu 0 Cu 0  Cu 2+ +2e - e-e- e-e- e-e- e-e- Cu 2+ V0V0 Electrolyte Cu 2+ Generalized Electrochemical Schematic Electrolytic Copper Deposition Ammeter Surface Area Current Density = Current Surf. Area

31 Semitool Confidential 31 Copper Interconnect Parameters: CD Uniformity = Surface Area R elec  1/Bath Conductivity R cat  1/Seed Thickness R cat  Wafer Radius R elec R anode = 0 V + Electrolyte Cathode (Thin) Anode (Thick) R cat R elec = Area

32 Semitool Confidential 32 R elec R anode = 0 V + Electrolyte Cathode (Thin) Anode (Thick) R cat R elec Edge I Loop Center I Loop How To MakeSmall? âV âCurrent Density âThroughput âR cat áSeed Layer Thickness âWafer Radius áR elec âBath Conductivity Copper Interconnect Parameters: CD Uniformity

33 Semitool Confidential 33 Conductivity at Various Bath Conditions Conductivity (mS/cm) 175 g/l H 2 SO 4 17 g/l Cu 80 g/l H 2 SO 4 50 g/l Cu 10 g/l H 2 SO 4 50 g/l Cu “Low” Acid “High” Acid Copper Interconnect Parameters: CD Uniformity

34 Semitool Confidential 34 0sec 5sec 15sec 30sec 60sec 120sec Current Density Wafer Radius Plating Time (0,0) Copper Interconnect Parameters: CD Uniformity Terminal Effect

35 Semitool Confidential 35 Current too Low Current too High The Effect of Current Density upon Gap Fill Bad Good 0.35mm, 4.3:1 AR Vias 0.18mm, 5.1:1 AR Trench Gap Fill Current Density LowHigh Optimum Fill for feature D Optimum Current Copper Interconnect Parameters: CD Uniformity

36 Semitool Confidential 36 Are the center and edge receiving the same process? Copper Interconnect Parameters: CD Uniformity

37 Semitool Confidential 37 Cathode Anode 2 V1V1 + V2V2 + Anode 1 Advanced Reactor Design: Multiple Anodes Robust system that can handle multiple chemistries Built for the future with the ability to handle shrinking die size Cost effective ability to handle increasing wafer diameters Copper Interconnect Parameters: CD Uniformity V 1 and V 2 adjusted until Independent of R c and R elec

38 Semitool Confidential 38 Dielectric Electrolyte Virtual Anodes Physical Anodes Wafer Conventional ReactorCFD Reactor Electrolyte Copper Interconnect Parameters: CD Uniformity

39 Semitool Confidential 39 Concentric Annular Anodes Electrolyte Bubble Trap Rotating Wafer Dielectric Flow Inlet Overflow Virtual Anode Copper Interconnect Parameters: CD Uniformity

40 Semitool Confidential 40 Superposition of Electric Field Wafer Diameter (mm) Normalized Voltage at Cathode (V) Anode 1 Anode 2 Anode 3 Anode 4 Summed Field Copper Interconnect Parameters: CD Uniformity

41 Semitool Confidential nm Seed layer, 1  m deposition High Acid 511mS/cm Low Acid 70mS/cm Conventional SEMITOOL - CFD Current Density (mA/cm^2) 0sec 5sec 15sec 30sec 60sec 120sec 133% Current Density (mA/cm^2) 0sec 120sec 20% <5% <5% Wafer Radius (mm) Copper Interconnect Parameters: CD Uniformity

42 Semitool Confidential 42 Dynamic Compensation for Constant Current Density Deposition Time (sec) Anode Current (Amps) Anode 2 Anode 3 Anode 1 Anode 4 Copper Interconnect Parameters: CD Uniformity

43 Semitool Confidential 43 Key Parameters for Overburden A.Local Overburden (Overplating) – Fill Step 1.Chemistry 1.3-Component 2.2-Component 2.Waveform 1.Direct Current 2.Pulse Reverse B.Global Overburden – Cap Step 1.Chemistry 1.High Acid 2.Low Acid 2.CFD Reactor Copper Interconnect Parameters: Overburden

44 Semitool Confidential 44 Copper Interconnect Parameters: Local Overburden Direct Current POR 3-Component Organic Package Moderate Acid Electrolyte Pulse Reverse POR 2-Component Organic Package High Acid Electrolyte Step Up No Step Up

45 Semitool Confidential 45 Copper Interconnect Parameters: Local Overburden Insufficient Leveler Planar Deposition Optimized Organic Conditions Overplating Post-CMP Residual Cu No Post-CMP Residual Cu

46 Semitool Confidential 46 Copper Interconnect Parameters: Global Overburden Cu Thickness (Å) Wafer Diameter (mm)

47 Semitool Confidential 47 Copper Interconnect Parameters: Global Overburden Raider CFD Profile Before & After 30s CMP 4,000 8,000 12,000 16,000 Thickness (A) POR Profile Before & After 30s CMP 4,000 8,000 12,000 16,000 Wafer Diameter Thickness (A) Early Clearing! POR Profile before CMP Profile after 30s CMP Edge Residual! CFD Profile before CMP Uniform Post-CMP Profile

48 Semitool Confidential 48 Copper Interconnect Parameters: Global Overburden CMP Profile Matching

49 Semitool Confidential 49 Copper Interconnect Parameters: Anneal Key Parameters for Anneal 1.Temperature 2.Feature Size 3.Barrier Layer

50 Semitool Confidential 50 As Deposited Self Annealed Thermally Annealed Small Grains Large Grains Copper Interconnect Parameters: Anneal Effect of Temperature

51 Semitool Confidential 51 Copper Interconnect Parameters: Anneal 1.0  m Trenches 0.25  m Trenches Effect of Feature Size Furnace Anneal Self-Anneal

52 Semitool Confidential 52 Copper Interconnect Parameters: Anneal Ta Barrier Layer TiN x Barrier Layer Strong Surface Interaction Reduced Migration Weak Surface Interaction Increased Migration Large Voids Effect of Barrier Layer

53 Semitool Confidential 53 Copper Interconnect Parameters: Anneal Anneal Temp Line Resistance Ta TaN x TiN x Grain Growth Void Formation Optimum Optimum Anneal Condition

54 Semitool Confidential 54 Backside Clean and Bevel Etch Why Backside Clean and Bevel Etch? Cu is a highly mobile ion Backside contamination can have adverse effects across the fab Unstable films on the edge of the wafer can cause surface damage at CMP Objective 1.Remove bulk Cu on the edge of the wafer 1.Delamination 2.Flaking 3.Yield Problems 2.Remove atomic Cu on the back of the wafer 1.Common Photolithography 2.Common Metrology 3.Cu ion diffusion

55 Semitool Confidential 55 Backside Clean and Bevel Etch Capsule 1 Chamber Cut Away Edge Exclusion Hardware Capsule 1 Features 1.Hardware control of bevel etch (BE) 2.0-4mm BE edge exclusion (EE) range 3.No front side protection needed 4.BE & backside clean simultaneously 5.Clean N 2 purged microenvironment

56 Semitool Confidential 56 Backside Clean and Bevel Etch Capsule Dynamics Wafer Device Up Seal Chamber Rotation Back Side Inlet: -Dilute Piranha Solution -DI H 2 O -N 2 Front Side Inlet: -DI H 2 O -N 2

57 Semitool Confidential 57 Backside Clean and Bevel Etch Capsule Dynamics Seal Chamber Rotation Back Side Inlet: -Dilute Piranha Solution -DI H 2 O -N 2 Front Side Inlet: -DI H 2 O -N 2 Wafer Device Up

58 Semitool Confidential 58 Backside Clean and Bevel Etch A concentric 1.5mm EE BE clears the notch Precision Control of Chemical Wrap-Around Critical Bevel Etch Parameters 1.Concentricity 2.Complete Cu Clearing 3.Clearing the Notch

59 Semitool Confidential 59 Backside Clean and Bevel Etch Precision Control of Concentricity Concentricity Spec (a) ≤ 0.2mm

60 Semitool Confidential 60 Backside Clean and Bevel Etch E Beam Spot MagnWD10 µm 10.0kV x17.1 STI. Bevel Etch No Copper on Edge Exclusion Zone No undercut Target ECD 1.0µm 1 µm ECD Copper 1.5 mm Edge Exclusion Profilometer Reading 52º Tilt on SEM <10 µm Precision Control of Copper Removal

61 Semitool Confidential 61 Why Cu Interconnects? Resistivity Reliability Damascene Process Flow Photolithography to CMP Parameters Affecting Cu Interconnects Gap-Fill Current Density Uniformity Overburden Anneal Backside Clean and Bevel Etch Bulk Cu on the Edge Atomic Cu on the Backside Summary

62 Semitool Confidential 62 Acknowledgements John Klocke – Cu Damascene Group Leader Kevin Witt – Cu Damascene Business Development Leader Tom Ritzdorf – Director of ECD Technology Jake Cook – Marketing Communications All Semitool personnel that have contributed data to this presentation


Download ppt "Semitool Confidential 1 Copper Damascene Plating 1/5/06 Brandon Brooks Process Development Engineer."

Similar presentations


Ads by Google