Challenges of Large Particle Size Analysis in CMP Slurries, and Opportunities for Improved Reliability

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1 Challenges of Large Particle Size Analysis in CMP Slurries, and Opportunities for Improved Reliability Budge Johl 29 th European CMP Users Symposium Spring 2013, Zurich, Switzerland

Outline Background and Importance of Large Particle Counts (LPC s) Challenges of Large Particle Size Analysis Improper slurry handling can compromise slurry health Data can be misleading if many of

2 Outline Background and Importance of Large Particle Counts (LPC s) Challenges of Large Particle Size Analysis Improper slurry handling can compromise slurry health Data can be misleading if many of the handling and sampling details are overlooked Tool challenges Opportunities for Improved Reliability Newer technologies: improve LPC resolution with 0.2µ node capabilities Improved operator training 2

Terminology of Particles Observed with SEM, ESEM & Light Microscope Particle: single solid sphere or other geometry Aggregate: multiple particles chemically attached to each other (chain) Agglomerate

3 Terminology of Particles Observed with SEM, ESEM & Light Microscope Particle: single solid sphere or other geometry Aggregate: multiple particles chemically attached to each other (chain) Agglomerate : particles and aggregates come together into closepacked clumps Micro gels: aggregates link together and form three dimensional network with water trapped within (Filter Plugging Problems) Particles Aggregate Agglomerate Microgel Ref.: R. Iler, Chapter One, The Chemistry of Silica, John Wiley & Sons,

Filtration Incoming Drums Source Drum Filtration Option Mix Tank

4 Typicial slurry fluid path Polishers Global Loop Recirculation POU Filters Global Loop H Wet N 2 Wet N 2 Wet N 2 Global Loop Filtration Incoming Drums Source Drum Filtration Option Mix Tank Post Mix Filtration Option SDS Day Tank Graphics Courtesy of BOC Edwards 4

5 Importance of Large Particle Size Analysis 5

Importance of Large Particle Size Analysis LPC s can play a major role in slurry troubleshooting, filtration and manufacturing optimization and wafer defect reduction LPC s can play an integral part

6 Importance of Large Particle Size Analysis LPC s can play a major role in slurry troubleshooting, filtration and manufacturing optimization and wafer defect reduction LPC s can play an integral part in evaluation of various slurry distribution components Pumps, valves, slurry distribution systems, in-line analytical tools, and slurry piping designs are only a few of the examples of where particle analyzers can be beneficial 6

7 LPC s: Slurry Distribution System Evaluations Diaphragm Pump Technology Vacuum Pressure Technology Magnetic Levitation (MagLev) Technology 7

8 LPC s: Pump Evaluations LPC s instrumental in Slurry Pump Evaluations Vacuum-Pressure Technology Diaphragm Pump Technology Bellows Pump Technology 8

9 LPC s: New Valve Technology Evaluations OLD TECHNOLOGY Tongue & Groove caused Areas for Slurry to Cake Up and Cause Premature Failure and Leak by NEW! TECHNOLOGY Enhanced Flow Characteristics No Areas for Entrapment or Agglomeration Slide Courtesy of Parker Hannifin Corp. 9

10 LPC s: New Valve Technology Evaluations Parker Old Valve vs. New ValveTechnology Levitronix Pump Recirculated Oxide Slurry Cumulative Counts > Diameter Old Valve Delta (24 Hour) New Valve Delta (24 Hour) Micron Size (µ) 10

11 Cumulative Counts > Diameter LPC s: Pump based Slurry Day-Tank Evaluations 1000 Particle Size Response of Oxide Slurry Control Vs. Maglev Tank Control MagLev Day Tank 100 ` Particle Size (µ) 11

12 LPC s: System Optimization (Humidification) Lack of humidified nitrogen blankets Control + Humidified N 2 - Humidified N 2 Field Example: Fab unaware that system was off. 12

13 Cumulative Counts > Diameter Normalized Values Correlating LPC s to Defectivity and RR Large Particle Counters Play a Critical Role in Evaluating Slurry Distribution Technologies Large Particle Size Response of Oxide Slurry (MagLev Pump) T0hrs T336hrs (1700 TO) Particle Diameter (microns) Defectivity and RR Response Oxide Slurry STANDARD (Time 0) MagLev (Time 336 Hour) = 1,700 Turnovers Defect Counts RR Wafer Results 13

Normalized Defect Data Cumulative Number (# Part > Diameter) LPC s: Filter Screening 2500 2000 1500 No Filter Company X 1 µm Company X 0.5 µm CUNO 0.5 µm 1000 500 0 0.6 1.0 1.8 3.0 5.2 9.

14 Normalized Defect Data Cumulative Number (# Part > Diameter) LPC s: Filter Screening No Filter Company X 1 µm Company X 0.5 µm CUNO 0.5 µm Particle Diameter (microns) µm Avg Defects No Filter 1 µm Filter X 0.5 µm Filter X 0.5 µm Filter CUNO Note: Similar Removal Rates Observed 14

LPC s: Critical Role in Filter Ratings Filter Ratings Beta Ratio β = Nu / Nd where Nu is the number of particles / ml from the unfiltered upstream Nd is the number of particles / ml from the filtered

15 LPC s: Critical Role in Filter Ratings Filter Ratings Beta Ratio β = Nu / Nd where Nu is the number of particles / ml from the unfiltered upstream Nd is the number of particles / ml from the filtered downstream LRV (Log Reduction Value) LRV = Log ([Feed] / [Filtrate] in particles/ml Percent Retention or Retention Efficiency % Retention = (1 (Filtrate/Feed)*100 or if know beta ratio is same as (1 1/β)*100 Efficiency can be derived from a known Beta ratio Ex = (βx 1) / βx * 100 where Ex is the efficiency for a given particle size Note: All these methods rely on large particle analysis 15

Percent Retention Retention LPC s: Critical for Creating Retention Curves Filter ratings are not all created equal Filter Retention Curves are Very Useful to Determine Effective Micron Size of the

16 Percent Retention Retention LPC s: Critical for Creating Retention Curves Filter ratings are not all created equal Filter Retention Curves are Very Useful to Determine Effective Micron Size of the Filter at various % Retentions These retention curves play an integral role in proper filter selection Retention Efficiency Curves for Planargard CMP Filters PureFlo CMP Capsule Filter Retention 100 CMP1 CMP % 90% 1 um 3 um 5 um 10 um CMP5 80% 60 CMP7 CM11 70% 40 CMP9 60% 20 CM13 50% CM Particle Size (microns) 40% Particle Size (um) (Retention Curves Courtesy of Entegris) 16

17 Challenges of Large Particle Size Analysis 17

Challenges of Large Particle Size Analysis The challenges are many: below are some of the main challenges faced Improper slurry handling can skew particle counting results Data can be misleading if

18 Challenges of Large Particle Size Analysis The challenges are many: below are some of the main challenges faced Improper slurry handling can skew particle counting results Data can be misleading if many of the handling and sampling details are overlooked Sample Bottles (are they clean?) Triple rinse with filtered DI water Sample collection threads of sample bottle clean and dry Sample bottles received in shipment Leaks & temperature control 18

19 Contributing factors that can alter LPC results: Unclean dip-tubes Dry slurry build up on slurry mix tank & day-tank walls Slurry distribution systems in need of a scheduled PM cleaning Dry slurry build up on prop mixers Settling ph shock during dilution Shearing (i.e. certain valves, pumps, piping design) 19

20 Contributing factors that can alter LPC results: Improper Mixing Large # of Turnovers Handling issues (i.e. lack of humidified nitrogen blankets), which may lead to increased LPC s and gels Dirty Sample Bottles (Garbage in Garbage Out) Dried Slurry on Sample bottle Caps and Threads as shown to increase LPC s 20

21 Some Possible Sources of LPC s Dried Slurry on Sample bottle Caps and Threads 21

22 Some Possible Sources of LPC s Dried Slurry on table top from removing sample bottle cap These dry particles also fall back into sample bottle during cap removal & skew LPC results 22

23 Some Possible Sources of LPC s Slurry on bottle threads when placed on cap 23

24 Possible Sources of Large Particle Issues Settling Improper mixing 24

25 Tools Challenged by Different Type of Particles Foreign particles (e.g. drum stirrers not properly adjusted can scrape the side of the drums and introduce large plastic particles) 25

26 Possible Sources of Large Particle Issues Dirty tote dip tube introduction to new tote Another source of large particle introduction 26

27 Possible Sources of Large Particle Issues How is the slurry being handled? Field Example: Handling Conditions Drum was left open to atmosphere A lot of dry slurry particles all over the top of the drum and the manual pump 27

28 Filter Housing Cleanliness Another source of large particles that may be introduced during filter change out 28

29 We Need to Bridge the Gap in Improving Reliability of CMP Slurry Large Particle Size Analysis 29

injection or pipette volume) Proper dosage being used Too low of a dosage and data is not repeatable Too high of a dosage tool

30 Improving Reliability Trained Operators Good technique for repeatable results (e.g. injection or pipette volume) Proper dosage being used Too low of a dosage and data is not repeatable Too high of a dosage tool counts multiple particles together as a larger particle and again skews results Know when tool has issues Dirty laser / fluid path Other components dirty from perhaps a previous run and carry over particles skewing results Condition of pneumatic valves and O rings on some models that are upstream to laser 30

Improving Reliability Tool capabilities or marketing hype In house evaluations to verify tool resolution & repeatability Use the correct tool for the job Calibration of tool from manufacturer Use of

31 Improving Reliability Tool capabilities or marketing hype In house evaluations to verify tool resolution & repeatability Use the correct tool for the job Calibration of tool from manufacturer Use of particle and count stds Baseline to help flag tool issues Track voltage readings of sensor on some makes Proper PM s including chemical flush cleaning of various components when necessary Know your laser capabilities (µ Range) 31

Common Large Particle Tool Detector Large Particle

troubleshooting and evaluations than analyzers that

Generation Large Particle Counters with Lower

32 Common Large Particle Tool Detector Large Particle Analysis has shown to be more beneficial in slurry troubleshooting and evaluations than analyzers that only give mean results µ Large Particle Counters Next Generation Large Particle Counters with Lower Detection Limits (0.2µ) (Animation Courtesy of Particle Sizing Systems ) 32

33 Tool Detection Limits Blue - Filter A Red - Filter B Black - Filter C 0.5µ Technology Shows Filters A, B & C Equivalent Blue - Filter A Red - Filter B Black - Filter C 0.2µ Technology Shows Filter A exhibited best LPC retention (Slide Data Courtesy of Brian Albert of DOW) 33

34 Improving Reliability of Results There are many particle counters available on the market today and will all generate data regardless of handling and operator technique However, it is important to pay attention to the many slurry handling and tool protocols in order to generate the best quality data Some counters are not as user-friendly and there is a lot of art involved in getting good repeatable data. Data can vary greatly from operator to operator Critical to have good training programs covering techniques and procedures Many tools lack good standard operating procedures (SOP s) and therefore on many occasions need to be developed in house 34

35 Improving Reliability of Results Some tools are prone to cavitations and degassing liquids more than others and may skew results and decrease repeatability Challenge when comparing data from tool to tool LPC does not always correlate with wafer defects Particle morphology and hardness are factors these tools miss However, with that said, Large Particle Analysis is still one of the best analytical methods of choice: To aid in slurry trouble-shooting Slurry filter optimization and recommendations Equipment and component evaluations 35

36 Improving Reliability of Results New improvements in laser technology and tool design is a continued challenge However, improvements have made it possible for 0.2µ technology allowing a more thorough analysis in an area where we have been blind in the past 36

37 References [1] Johl, B., Benefits and Limitations of Slurry Particle Analysis and the Need for Next generation Capabilities, Rohm and Haas Electronic Materials. Venue: CMP Symposium, Santa Clara, CA, 2009 [2] Johl, B.*, H. Porter* and Adrian Quantik**. Klebosol Slurry Compatible with New MagLev Day-Tank Technology, Rohm and Haas Electronic Materials* and Levitornix, LLC**Venue: 25 st International VMIC Conference, Fremont, CA, USA, October 2008 [3] Johl, B., Importance of Optimized Slurry Filtration for Reducing Wafer Defects, Rohm and Haas Electronic Materials. Venue: CMP Users Conference, Santa Clara, CA, 2006 [4] B. Johl, H. Porter, Investigation of Valve Effects on Wafer Defectivity using an Oxide Slurry, Venue: Levitronix CMP Users Conference, Santa Clara, CA, February 2006 [5] Johl, B., Slurry Handling, Troubleshooting and Filtration, Venue: Levitronix CMP Users Conference, Santa Clara, CA, February 2005 [6] B. Johl, M. Litchy, R. Schoeb, Effect of a Maglev Centrifugal Pump on Slurry Health and Defect Rates, Venue: PacRim Int. Conference, Korea, 2005 [7] Johl, B.*, and M. Tseng**. Impact of Point-of-Use Filtration on ILD CMP Process, Rohm and Haas Electronic Materials* and CUNO Inc.**Venue: 21 st International VMIC Conference, Waikoloa Beach, Hawaii, 2004 [8] Johl, B. and N. Bishop. Dynamic Pot-Life and Handling Evaluation of Celexis for STI, Rohm and Haas Electronic Materials and Trebor Pump. Venue: 21 st International VMIC Conference, Waikoloa Beach, Hawaii, 2004 [9] B. Johl, R. Singh, Optimum Process Performance Through Better CMP Slurry Management, Solid State Technology, August 2003 [10] B. Johl, et al., Dynamic Pot-Life and Handling Evaluation of EPL2362 First Step Copper Slurry, Proc. 8th Int. CMP Conference, Marina Del Ray, CA, February 2003 [11] R. Singh, B. Johl, Characterization of a Silica Based STI CMP Slurry in a Vacuum-Pressure Dispense Slurry Delivery System and Pump Loop, Proc. VMIC Conference, 2001 [12] Adrian, K. and B. Johl. Evaluating Millipore Planargard Filters with Rodel CUS3115 Copper Slurry in BOC Edwards P4400, Venue: CMP Users Group Annual Symposium, San Jose, CA, 1999 [13] J. Bare, B. Johl, T. Lemke, Comparison of Vacuum-Pressure vs. Pump Dispense Engines for CMP Slurry Distribution, Semi Workshop, July 1998 and Semiconductor International, January 1999 [14] J.P. Bare, B. Johl, Comparison of Humidified vs. Non-humidified Vacuum Pressure CMP Slurry Distribution Systems, Proc. VMIC Conference, 1998 [15] J.P. Bare, B. Johl, Accelerated Aging and Handling Evaluation of Rodel ILD1300 Oxide CMP Slurry, Proc. AVS N. Calif. CMPUG Annual Symposium,

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Benefits and Limitations of Slurry Particle Analysis and the Need for Next Generation Capabilities. Budge Johl

Benefits and Limitations of Slurry Particle Analysis and the Need for Next Generation Capabilities Budge Johl 2009 5 th Annual Levitronix CMPUG Symposium Particle Analyzers Particle size analysis can play