CMP Technological Paradigm Shift To Surface Cleaning. Hong Jin Kim Advanced Module Engineering, GLOBALFOUNDRIES

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1 CMP Technological Paradigm Shift To Surface Cleaning Hong Jin Kim Advanced Module Engineering, GLOBALFOUNDRIES

2 Presentation Focus On.. CMP-induced Defects: -. CMP Process -. Role and Effect of CMP in-situ Cleaning -. Brush Cleaning -. Examples of CMP-induced Defects and Their Removal Cleaning Perspective of CMP Process 2

3 CMP: Planarization Technology Planarization & Polishing Material Removal & Separation 3

4 CMP Equipment: Polisher and Cleaner Polisher Cleaner Megasonic Brush Scrubber Non-Contact Cleaning (ex. fluid jet) Polishing and cleaning are in-situ process: polishing cleaning at the same equipment 4

Historical CMP Technology Development 1927,

Raytheon, first practice CMP for planarization

for STI for STI 1986, CMP developed in IBM,

1989, oxide/al/w CMP implemented 1991, IC pad

d for CMP 1997, 1 st CMP textbook 2000, 300mm

what to my wafer, Korea CMP User Group Meeting

Rhoades, Chemical Mechanical Planarization:

5 Historical CMP Technology Development 1927, Preston published glass polishing theory 1972, Raytheon, first practice CMP for planarization 1983, IBM first planarized Pbsilicate glass for STI 1983, IBM first planarized Pbsilicate glass for STI 1986, CMP developed in IBM, called FRED 1987, CMP development begin at IBM 1989, oxide/al/w CMP implemented 1991, IC pad born 1995, 1 st ph.d for CMP 1997, 1 st CMP textbook 2000, 300mm CMP setup in industry for manufacturing , CMP developed explosively in materials, consumables, tools and functions 2017, Core process in the semiconductor manufacturing Michael Fury, You want to do what to my wafer, Korea CMP User Group Meeting 2014 Gautam Banerjee and Robert L. Rhoades, Chemical Mechanical Planarization: Historical Review and Future Trend, ECS Transactions, 2008 Images from google 5

Gargini, SPCC2016 Practical scaling may end at 10nm?

6 ITRS Roadmap Transistor Scaling: 1.Geometrical Scaling ( ~ 2003) 2.Equivalent Scaling ( ~ 2021) 3.Power Scaling ( ~ 203x) P. Gargini, SPCC2016 Practical scaling may end at 10nm? Or 7nm will be an end of scaling? Image from google 6

7 Yield Impact by CMP Yield Detractor Pareto CMP-induced defects CMP-induced Defects Impact on yield detracting becomes higher and higher at 14/sub 14nm logic device

8 Cleaning Technology Development Cleaning Technology Development Brush cleaning Cryogenic cleaning Megasonic cleaning 2-fluid Jet Advanced Nozzle Gigasonic Wave Advanced Mechanical Cleaning Electroscrubber Double Feature Post Polishing In-Situ Cleaner < 2000 Brush cleaning is method for post CMP in-situ cleaning Hyo San Lee, Next Generation Particle Cleaning, Semicon Korea, Brush cleaning is still main method for post CMP in-situ cleaning 8

9 Post CMP in-situ Cleaning CMP: is known as the most defect generated process in semiconductor fabrication However, CMP is also highly favorable process condition for cleaning aspect cf. Challenges of wet cleaning (ex-situe): pattern damage, strong adhesion of small particle (at dry surface state) to wafer surface CMP (pros and cons as cleaning perspectives): In-situ process Flat surface: no pattern damage strong physical cleaning acceptable Single wafer process Wet process: weak adhesion between particle and wafer surface Sufficient material undercut No standard method to estimate particle removal efficiency Variation in incoming wafer surface and defect level is very high Limited cleaning chemical available for manufacturing (HF, SC-1, NH4OH )

10 Strategy for Post CMP In-situ Cleaning Wet Cleaning Strategy for the Next Generation Hyosan Lee, Next Generation Particle Cleaning, Semicon Korea 2015 Cleaner Clean chemical Dryer Brush, Brush..

11 Particle Removal vs Contamination Brush Contact Particle removal: drag force > adhesion force f (brush RPM, brush gap ): higher brush RPM high particle removal Wafer contaminated by brush cleaning more contact, more particle Ref.) Ahmed A. Busnaina, IEEE TRANSACTIONS ON SEMICONDUCTOR MANUFACTURING, VOL. 15, NO. 4, NOVEMBER 2002, pp Ref.) H-J Kim et.al., MICROELECTRONIC ENGINEERING 136, 2015, PP

12 Brush Cleaning and Defect Signature Defect Signature by Brush Cleaning Brush Gap Brush RPM Chem. Flow Physical Force Contact Behavior Friction Torque Porosity Post Brush Clean Defect??? Brush Cleaning is NOT ONLY clean the wafer BUT ALSO contaminate wafer PRE vs C.C. 12

13 Effect of Brush Recipe on Cross Contamination Low RPM longer contact duration high cross contamination Optimum RPM high PRE & optimum duration lowest cross contamination High RPM high contact frequency increase cross contamination Negative brush gap high down force increase contact area high cross contamination At 0 gap nodule non-uniformity high cross contamination/ low PRE 13

14 Effect of Brush Lifetime

Effect of Cleaning Chemistry Cleaner chemistry sensitively influence post CMP defects, HOWEVER, there are limitation to utilize non-conventional cleaner

15 Effect of Cleaning Chemistry Cleaner chemistry sensitively influence post CMP defects, HOWEVER, there are limitation to utilize non-conventional cleaner chemistry in post CMP in-situ cleaner 1)post polish exposed materials damage, 2)CMP in-situ cleaner design (not good for strong chemical), 3)brush/roller damage

Sigma, normalized Brush Cleaning Optimization Impact on defectivity

60% improved Optimized brush cleaner 1.00 0.

is sensitively influenced by brush cleaner module.

chemical has etch rate) Knobs for optimize Chemistry Spray bar

16 Sigma, normalized Brush Cleaning Optimization Impact on defectivity Non-optimized brush cleaner Impact on uniformity WIW STD: more than 60% improved Optimized brush cleaner Non-optimized brush cleaner Optimized brush cleaner Defectivity is sensitively influenced by brush cleaner module. There is challenge to improve uniformity as well (if cleaning chemical has etch rate) Knobs for optimize Chemistry Spray bar position Chemical flow rate and flow stability Roller rotational torque Brush gap calibration Brush wobble Brush pre-treatment 16

17 W Corrosion Effect of Brush Cleaning Defect (Line Void) Map Brush Lifetime Dependency 17

18 Ring Scratch Effect of Brush Cleaning Defect (Scratch) Map Mechanism for Ring Scratch Ping Hsu, Solid State Phenomena, 219 (2015), pp Particle Agglomeration Mechanism: Surface charge difference at different chemical environment particle agglomeration trapped in the brush scratch formation during brush cleaning

19 Effect of Slurry Incoming Wafer Effect Polishing with Slurry A - Cleaner Polishing with Slurry B Cleaner CMP cleaner performance is sensitively influenced by slurry

20 Effect of Cleaner Contamination Tool Type Megasonic BB1 BB2 Dryer A B 1 st cleaner loaded defects more than following cleaner. Contamination depends on tool.

21 Clean Chemistry and Etch Rate Effect 1Å etch amount delta impact post CMP defects? CMP in-situ cleaning is very sensitive to clean chemistry and its properties.

22 Clean Chemical Decoration Effect CMP-induced microscratch enlarged by HF etch Polished Not polished CMP in-situ clean (HF case) process

23 Defects induced by Dryer Case I: random water mark Case II: incomplete dry Dryer has no monitoring function Incomplete dry caused water mark defects Controlling end point at drying is necessary

24 Effect of Cleaner Module Design: Blanket Wafer Case I Case II Case I Case II Cleaner Module Configuration Case I: Brush Clean Brush Clean Spin Rinse Dry Case II: Brush Clean* & Non-Brush Clean Combination Spin Rinse Dry*

25 Effect of Cleaner Module Design: Pattern Wafer Case I Case II

26 Effect of Defect Inspection Criteria BIN Size - 120nm BIN Size - 65nm Defect performance is different depending on inspected defect size Tool A and Tool B comparable?

27 RMG-MOL Process in Advanced Node Device FEOL BEOL

Challenges in Advanced Node Device I W Clean Chemistry

Capping layer HK Post Metal Gate CMP: 1)Gate Metal, 2)Barrier

28 Challenges in Advanced Node Device I W Clean Chemistry Requirements: 1. No damage on various metals 2. No W corrosion 3. Minimal material loss (etching) ILD oxide Barrier WF metal Capping layer HK Post Metal Gate CMP: 1)Gate Metal, 2)Barrier Metal, 3)WF Metal, 4)Capping Metal, 5)High-k Dielectric, 6)ILD Oxide Various materials exposed to polishing slurry/clean chemical

29 Challenges in Advanced Node Device II Critical Defect Size: Contact to RMG

30 Chemical Mechanical Cleaning Effect of chemical buffing polishing on defects CMP CMC Buff CMP with cleaning chemical: Chemical Reaction + Physical Force to Wet Wafer Surface Effective cleaning process. No (Min.) material removal required (not matured process in industry yet)

Challenges and Opportunities Brush Cleaning Early brush defect Minimize cross contamination New design of brush and brush nodule Pre-broken

performance of particle removal associated with brush cleaning No material damage with multi materials exposure Low cost, eco-friendly

31 Challenges and Opportunities Brush Cleaning Early brush defect Minimize cross contamination New design of brush and brush nodule Pre-broken brush Optimized brush properties, ex) porosity, pore size, softness Clean Chemical Almost same chemicals used for more than 15 years High performance of particle removal associated with brush cleaning No material damage with multi materials exposure Low cost, eco-friendly chemical (in particular, for Cu CMP) Cleaner Module Non-contact type cleaner module New design on cleaner module for advanced cleaning Monitoring for dryer

32 Is CMP planarization technology or cleaning technology?

33 Summary Paradigm need to be shifted. Planarization /Polishing Cleaning CMP concept now encompasses cleaning in addition to traditional planarization concept. And role of cleaning becomes much more critical than previous device. CMP CMPC: Chemical Mechanical Polishing and Cleaning

CMP Technological Paradigm Shift To Surface Cleaning. Hong Jin Kim Advanced Module Engineering, GLOBALFOUNDRIES

CMP Technological Paradigm Shift To Surface Cleaning Hong Jin Kim Advanced Module Engineering, GLOBALFOUNDRIES Presentation Focus On.. CMP-induced Defects: -. CMP Process -. Role and Effect of CMP in-situ