Fundamentals Of Post-CMP Cleaning Of Dielectric Surface .
20TH SURFACE PREPARATION AND CLEANING CONFERENCE (SPCC) ‒ 2018Fundamentals of Post-CMP Cleaningof Dielectric Surface Contaminatedwith Ceria (Nano-to-Micro) ParticlesAtanu Das, Daniela White,Wonlae Kim, Michael WhiteR&D Surface Preparation and IntegrationDanbury, CTT 1 203 207 9397Email: atanu.das@entegris.com
AGENDA01Fundamentals of Ceria-Silica CMP Process02Reactivity Between Ceria and SiO2 and Si3N403Commodity Cleaner vs. Formulated Cleaners04Formulation Design Concept and Components05Ceria Cleaning Mechanism –Spectroscopic Evidences06Positive vs. Negatively Modified Ceria Cleaners07Entegris Recommendations08Conclusions
POLISHING OF SiO2 FILMS BY CeO2 PARTICLES – PROPOSED MECHANISMCeria – CMP process Key steps and factors determinesilica removal:padCeO2 particle Si–O–Ce bond formationCeO2 particle Particle size distributionCe Ce CeO- OOO- O-OO-lump of SiO2 Hydrodynamic forces actingat the interfaceO- O- Pad propertiesSiSiSiSiSiSiSiSiO2 film (bulk)SiSi Fluid RheologyDispersionof SiO2SiO2 film (bulk) CMP doesn’t always removeSi – O – Ce from surfaceOverall reactionRRSi―OH BaseSi―O‒ HOCeR'RSi―O‒ BaseH RSi―ORef: T. Hoshino et al. / Journal of Non-Crystalline Solids 283 (2001) 129-136 Challenges:Ce An effective post-CMP formulationneeded to clean the surfaceR' OH‒
REACTIVITY BETWEEN CERIA AND SILICON NITRIDE (WHY MODIFY CeO2?)CeO2–Si3N4 surface interactions (3 key steps)Step 1: Silicon nitride hydrolysisRRRR subsurface neighboring atomR‘ surface atom covalently bondedto nitrogen (silicon or hydrogen)ROH2RRR'R'R'R'RH2ORRR'R'R'R'RR'R'Step 2: Reaction of the surface silanols/oxoanionsStep 3: Removal of the surface oxide layer with ceria particleAppropriate organic base can influence silicon nitride hydrolysisR'R'RRR'Base RBaseBaseRR'R Organic base can create a new acid-base equilibrium Deprotonate the surface amide Site-block water from silicon metalRR'R'T. P. Johns et al. Electrochemical and Solid-State Letters, 8 q8r G218-G221 (2005)CeO2 is modified with appropriateorganic base to tune the Si3N4 removal
WHY FORMULATED CERIA CLEANERS VS. COMMODITY?1. EHS/Safety concerns with traditional cleans(hot SPM, dHF, SC-1, TMAH dHF)2. One-step clean process requirement forthroughput improvement3. Need for improved particle removal4. Need for improved metal removal5. No damage to dielectric substratesPositive CeriaProcessCMP/PETEOS/Ceria ParticlesProcessCMP/PETEOS/Ceria ParticlesCommodityCleanersDefectsParticlesNegative CeriaSC-1 (1:1:5)(dHF SC-1 SPM)CeO2CeO21. Many different ceria particles and chemistries areon the market2. Cleaning challenges vary greatly depending onslurry type no universal cleaner so far3. Best approach is for slurry supplier to collaboratedirectly with cleaning supplier and customer todevelop the best BKMPlanarCleanAG Ce-XXXXPlanarClean AG Ce-XXXX-1PlanarClean AG Ce-XXXX-2
INTERACTIONS OF ORGANIC MOLECULES WITH CERIA SURFACE AND SURFACE CHARGE VS. pHSurface-modified ceria in CMP slurriesVarious CeO2 Particles TestedLow pHz 0 mV-High pHz 0 mVSurface modified CeO2 particles in the CMP slurries: positive or negative surface charge;Particle size: 15 – 200 nm;Need to understand CeO2 surface chemistry and types of interactions with the dielectric surfaces;Six different types of CeO2 particles tested – can we design an universal cleaner?
DIFFERENT CLEANING FORMULATIONS FOR DIFFERENT CERIA SURFACE CHEMISTRIES?Particles B, C, DParticles E, F More acidic surface, partially hydroxylatedSmall amount of surface water H-bondedSurface exposed –OH for -Si-O- condensationStronger Ce-O-Si bonds, difficult to break/clean More basic surface, more hydroxylatedOuter-sphere shell of H-bonded waterReduced surface reactivityWeaker Ce-O-Si bonds, easier to breakBased on the FTIR-ATR, UV-VIS and titration experiments data
HOW DOES THE COMMODITY CLEANER WORK? AN EXAMPLEReduction of Ce(IV)Commodity cleaners as controls:SC-1 – H2O:H2O2:NH3 (1:1:5)SPM – H2SO4:H2O2 (1:4), T 100 CProduces more Ce(III)Drawback: H2O2 can attack to the dielectric Basic – H2O2 dissolve more oxide SPM – additional step needed forleftover sulfurCe(IV)Ce(III)ComplexingagentSoluble Ce-ionOxidation of Ce(IV)Overall reaction2 H2O2 2H O22H Complexant (C)CProduces more Ce(IV)Wei-Tsu T. et al. Journal of Solid state Science and Technology, 6 (10) P7118soluble
SURFACE INTERACTIONS AND KEY BOND-BREAKING STEPSCeO2-SiO2 Surface InteractionsCe-O-Si Bond-Breaking iSiCeO2O‒O‒O‒SiSiSiCeO2OO‒SiSiChemical bondCe – O – Si1. Nucleophilic attack of OH- to rmulation design concepts:SiSiSi SiO21. High pH hydrolysis of -Ce-O-Si- bonds byHO- nucleophilic attack to Ce-center -Si-OHHO‒3. Breaking of (CeO2)–SiO2 bond2. Additives needed to stabilize –Ce-OHspecies and prevent redepositionH O‒H O‒H O‒H O‒H O‒H O‒H O‒H O‒SiSiSiSiSiSiSiSiCleaning formulation (low or high pH) can be designedbased on types of ceria and its interaction to the surface92. Partial etch of the surfaceCeO2HO‒-Ce-OHCeO22Three possible options:3. High pH partial etch/dissolution of thesurface –Si-O-Ce- groups redispositionprevention.4. Low pH: Bond-breaking additives,followed by CeO2 complexation, andparticles stabilization and dispersion
INTERACTIONS OF CE(IV) AND CE(III) SALTS WITH CEXXXX-01: MONITORED BY CV EXPERIMENTCe(IV) CeXXXX-01Ce(III) CeXXXX-01CeXXXX-01Ce(III)-saltCe(IV)-salt Ce(IV)/Ce(III) redox couple can’t be detectedin the solvent potential range CeXXXX-01 redox wave remains unchangedafter the treatment with Ce(III) or Ce(IV) salts Redox property of CeXXXX-01 componentremains active for Si – O – Ce bond breaking
SPECTROSCOPIC EVIDENCE OF ACTION OF BOND-BREAKING COMPONENTTreated CeO2 AG CeXXXX-1No complexformationC1C1CeO2C1C1FiltrateRed: AG CeXXXX-1Blue: AG CeXXXX-1 without activebond-breaking componentBlack: AG CeXXXX-1 (untreated)Samples were collected after the PCMP processWithout the active bond-breaking component, no complex formationwas observed, indicating component helps to keep the ceria soluble11
LOW PH FORMULATION DEVELOPMENTCeO2 (powder) Formulation PurposeCe Ion Dissolution Ceria particle dissolution comparison Test conditionspH 2.2 CeO2 powder (from Aldrich) Chemistry: CeXXXX-01, CeXXXX-02pH 13.1 Chemistry dilution (100:1) ProcedureCeXXXX-01CeXXXX-02 Add CeO2 in chemistryStir for 15 minFilter the powderICP MS analysis for Ce ionCeXXX-01 and CeXXX-02 can dissolve certain amount of Ceria powderCeXXX-01 shows better Ceria powder dissolving than CeXXX-02
LOW PH FORMULATION FOR NEGATIVE CERIACeO2CeO2CeO2Additive changesthe surface chargesCeO2CeO2CeO2OOOOOOSiSiSiSiSiSiStrong ionic attraction leads to poor cleaningRight additive changes the surface charges.As a result, strong repulsion leads to better cleaning.
CLEANING PERFORMANCES WITH AND WITHOUT ADDITIVES300000Total Area of ive500000Ce-XXXX-01CIP ACe-XXXX-03CIP BReferenceCleaning additive has strong effect in changing the surface property of CeO2 particlesChoosing the right additive is one of the key steps to design efficient formulation
CLEANING OF POSITIVE-CeO2 ON PETEOSPETEOSTotal Area of Ceria60000 No H2O2 or HF was used in the formulation50000 Compare to commodity cleaner (H2O2 NH4OH),CeXXXX-4 sows 150 improvement4000030000 No CeO2 agglomeration indicates soluble Ceriaformation or better dispersion after PCMP process20000100000uncleaneduncleanedAG Ce1101CeXXXX-4SC-1 (1:1:5)SPM SC-1 (1:1:5)AG CeXXXX-4SC-1SPM SC-1
TREATMENT OF POSITIVE-CeO2 WITH CLEANER SOLUTIONTreated-CeO2 CleanerStir 5 minMeasure particle size190185180Diameter (nm)175170165160155150145No particle agglomeration was observedSample 6 show highest reduction of size; indicates higher degree of surface interaction with the cleaner
CONTACT ANGLE EXPERIMENT TO MONITOR ORGANIC RESIDUE REMOVAL EFFICIENCYSiSiSiSiSiWater contact SiSiSiLess hydrophobicWater Contact Angle Variation on Contaminated vs.Clean PETEOS, Polysilicon and Si3N4 Substrates60DI iconSi3N4Contact angles are reduced after cleaning with CeXXXX-06 and 07Surfaces become more hydrophilic, indicates less organic residue leftover after the cleaning
CONCLUSIONS Understanding the nature of Ceria surface and interaction with the Silica surface are the key to designing theproper cleaner Spectroscopic evidence suggests that the right bond-breaking component is essential to remove Ceria from surface Different bond-breaking reagent are necessary for each type of Ceria at different pHs Several low-pH and high-pH high-performance Ceria cleaning formulation, AG-CeXXXX were developed at Entegris,based on in-depth mechanistic understanding on Silica-Ceria surface interactions So far there is no universal ceria cleaner
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01 Fundamentals of Ceria-Silica CMP Process . Soluble Ce-ion Produces more Ce(III) Produces more Ce(IV) Drawback: H 2 O 2 can attack to the dielectric Basic –H 2 O . Understanding the nature of Ceria surface and interaction with the Silica surface are the key to designing the
CMP CLUB PAY BACK PROGRAM: Again this year, the CMP will have its Club Pay Back Program, where 5.00 per competitor will be awarded to any CMP Affiliated Club that has 5 or more of their members attending and participating in the Western CMP Games & CMP HP Rifle matches. The club members will need to present his or her club ID card at the event.
New Developments in Post-CMP Cleaning Technology - Singh et al. ERC TeleSeminar, University of Arizona, February 10, 2011 4 ENTEGRIS PROPRIETARY AND CONFIDENTIAL PCMP Cleaning Challenges for Advanced Applications CMP intensity (i.e., number of wafer starts) as well as complexity (e.g., 15 CMP
History of CMP Rules. The first CMP Competition Rules were revisions of Army Regulation 920-30 that governed the National Trophy Matches prior to the creation of the new CMP in 1996. This is the 23rd Edition of the CMP Highpower Rifle Competition Rules. Substantive rule changes from
basis. Unlike other cards and coupons, CMP coupons are issued by the CMP and not by DPA. A CMP coupon contains the recipient’s name, ID number, and the names of the primary provider and pharmacy that have been selected for the recipient. If a replacement CMP card/coupon is nee
PGW MU MV MW NGU NGV NGW RS (15V) Motor (7.5V) ) CMP Vref Filter FG FG CMP ) 0.5V CMP ) LVSD ALL OFF PWM 1.23V Lap GH HUN HWN HVN CMP ) C2 - Noise F
Oct 17, 2011 · Temperature: 10 C to 70 C Platen/Carrier rpm: 20 to 80 Slurry flow rate: 100 to 200 mL/min Typical removal rates: Oxide CMP 2800Å/min Metal CMP 3500Å/min -CMP is a process of smoothing surfaces with the combination of chemical and mechanical forces. Figure 6. Basic design of CMP [5].
The following topics in the Introduction to Green Cleaning and Green Cleaning Programs training manual were covered: § New York State Green Cleaning Product Mandates and products currently covered under the mandates; § Reasons for creating the green cleaning mandates; § A description of green cleaning;
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