JULY Challenges in Cleaning Tungsten and Cobalt for Advanced Node Post CMP and Post Etch Residue Removal Applications

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1 JULY Challenges in Cleaning Tungsten and Cobalt for Advanced Node Post CMP and Post Etch Residue Removal Applications Michael hite. aniela hite, Thomas Parson, Elizabeth Thomas, Shining Jeng, Ruben Lieten, Volley ang, Sean Kim, isma Hsu and Steve Lippy

2 AGENA 01 Cleaning requirements for Co and at the advanced Node 02 Co cleaning mechanisms 03 Controlling corrosion on Co 04 Cobalt defectivity improvements 05 Cobalt wet etch & cleaning 06 Cleaning mechanisms 07 Cleaning Si 3 N 4 after polishing 08 wet etch & cleaning 09 Conclusions 2

3 CLEANING CHALLENGES FR ULK CALT AN TUNGSTEN Post CMP ulk Co Cleaners Post CMP Cleaners Post Etch Residue Remover Replace more traditional copper cleaners with rationally designed Co cleaners Low/No Cobalt corrosion Low/no galvanic corrosion Low/no dendritic Cox growth Low/no Co pitting Low/no organic residues Low/no silica particles or clusters No increased roughness Green chemistry (TMAH free) Market increasing challenged by recess High ph commodities (SC1, dil NH 3 ) Traditional low ph cleaners Low etch rates (<2 Ǻ/min) Low/no rganic Residue Nitride cleaning is particularly problematic Low no silica particles or clusters No increased roughness Green chemistry.(tmah free) Post Etch Residue Remover.- Cu,, Co Multi Function Cleaner - Clean + Etch etc PERR for advanced FEL application (Ge and SiGe) Green chemistry (TMAH free) 3

4 THE RATINAL ESIGN F A PST CMP CLEANER PLANARCLEAN AG CPPER CLEANING PlanarClean AG Advanced Generation Copper Cleaning Mechanism Cleaning additive disperses silica and organic residue and prevents reprecipitation Si 2 Etchant for controlled, uniform Cu x dissolution to undercut particles rganic additive attacks and removes Coorganic residue Corrosion inhibitor package controls galvanic corrosion High ph leads to charge repulsion between negatively charged silica and negative cobalt oxide surface Si H Q Si 2 2 Si 2 H Co n+ Co Co/Co 2 3 Co(0) 4

5 H PLANARCLEAN AG PREVENTS SILICA AGGREGATIN Particle adhesion mechanisms Physisorption (van der aals attraction increases with PS) Si + Si SiH + H - Si - + H 2 Electrostatic attraction or repulsion (zeta potential) IEP = 4 Chemisorption (chemical reaction particle-surface) Capillary condensation H Si 2 H H H H H H Si 2 H H H H H H H H Si 2 H H H H H H Post-CMP H Co H Si 2 H H H H AG-3XXX H Si 2 H H Post-CMP Co H Si 2 H H Zeta Potential z = 4pg(n/E)/e ispersed particles Highly negatively charged No particles agglomeration 5

6 SME CHALLENGES ASSCIATE ITH C CLEANER EVELPMENT H - H 2 H 2 Co Pourbaix iagram Mt n+ X n- Co + Co 2 3 Co H 2 2 H - H 2 H 2 H - Co 2+ H 2 H 2 K sp = 1.6 x Ideal ph range for Silica slurry removal to prevent hydroxide precipitation 6 H H H H H H H H H Co + Co 2 3 Co Surface passivation Co passivation by both cobalt oxide/hydroxide and/or corrosion inhibitor Can result in Co x (H) y growth without the proper complexing agent H 2 Co 2+ H 2 H 2 6 L L L L [] 3 H - Co 2+ L L L K sp = soluble H - H - Co 3+ H - H 2 K sp = 1.6 x H 2 H 2

7 SME CHALLENGES ASSCIATE ITH C CLEANER EVELPMENT AFM ell-passivated Co surface AFM, SEM no Cox surface precipitates, low surface roughness (R a = 5 nm) Uniform, smooth etching (no pitting) Poorly passivated surface or insufficuent complexation endritic Cox growth SEM 7

8 PTENTIYNAMIC REUCTIN F C XIE LAYERS CAN MEASURE THE RELATIVE CNCENTRATINS F C(II) AN C(III) XIE/HYRXIES 0 Co tsmc CV Co in ph 11.5 KH Q = Coul Thickness = 43.94Å I (A) Co Q = Coul Thickness = 41.95Å E (V vs. Ag/AgCl) 8

9 XPS FITTING SHS CALT(II) AN CALT(III) CAN TH E PRESENT 9

10 NYQUIST PLTS SH INFLUENCE F PRPER INHIITR SELECTIN AN CNCENTRATIN N CALT PASSIVATIN High Inhibitor 2 High Inhibitor 1 Higher impedance storage and loss components higher film integrity Low Inhibitor 2 No Inhibitor hen -> 0 Z = R ( 1/ 2 C dl 1/ 2 Rct 2 2 1) C ( R 2 dl ct 1/ 2 ) 2 Cdl ( R Z = 1/ 2 ( C ct dl 1/ ) Cdl / 2 1) C ( R ) dl ct 1/ 2 2 a 10 Ref: 1. ang, et al. SPIE eijing 2016 Conf. Proc. 2. ard, A. J. Faulkner, L. R. Electrochemical Methods: Fundamentals and Applications; iley and Sons 2001

11 AG- C FRMULATINS SH UP T A 2X IMPRVEMENT IN EFECTIVITY VER CMPETITR Silica particle 2.5x Silica cluster rganic residue Judicious selection of cleaning additives leads to lower defectivity 11

12 TITANKLEAN MECHANISM FR REMVING RY ETCH RESIUES HILE PRTECTING CALT ESL 1 ESL 2 Low -ĸ rganic/inorganic residues Co et Cleaning Low -ĸ Co Etchant Co/ESL Co/ESL protection M complex Etchant Metal inhibitor Co/ESL M complex X ESL/inorganic residues removal Etchant Chelating agent TK 162 M 3+ M 2+ residues low-ĸ Residues from dry process TitanKlean xidization egradation Swelling & dissolution Residues removal Etchant Solvent Mukherjee, T. Thesis N. Texas U.,

13 PLANARCLEAN AG- CLEAN MECHANISM FR ALUMINA R SURFACE TREATE SILICA (ST-Si 2 )-ased CMP Slurries Polishing produces many particles (slurry, metal, and organics) Component A Insures negative charges on surface and organic particles. rganic Particle Al 2 3 Metal Particle Al 2 3 rganic particle Metal Particle rganic particle PC AG- formulations: Metal Particle ST(+)-Si 2 rganic Particle ST(+)-Si 2 Metal Particle Comp & modifies particles surface and creates negative surface charges Al 2 3 Al 2 3 ST(+)-Si 2 ST(+)-Si 2 Al 2 3 ST(+)-Si 2 rganic particle Metal Particle Removed by I Rinse Inhibits corrosion Controls the etch rate Particle and surface modification ielectric compatibility Non-TMAH additives for organic residue removal 13

14 HIGHER TUNGSTEN ETCH RATES ITH INCREASING ph UE T ISSLUTIN AS PLYXTUNGSTATE KEGGIN INS SC1: 1:50 > 6 A/min il NH 3 (1:2850) 3 Negative at all phs of interest Liu, et al. J. Mater. Chem A, Issue 6, 2014 "Hetero and lacunary polyoxovanadate chemistry: Synthesis, reactivity and structural aspects". Coord. Chem. Rev. 255:

15 MECHANISMS FR IMPRVING RGANIC RESIUE REMVAL FRM SI 3 N 4 STUIE Y CNTACT ANGLE AN FTIR AG- Cleaner Electrostatic Repulsion during CMP Contact Angle Si 3 N 4 surface typically Highly contaminated by cationic dishing and erosion control agents Cleaning additive removes cationic Contamination form dielectric surface and disperses dirty dirty FTIR Si 3 N 4 Control clean clean clean, hydrophilic

16 PLANARCLEAN AG- FRMULATINS EXHIIT LER EFECTS AN RGANIC RESIUES VER TRAITINAL CLEANS Si N # ER defects Review pareto (>= efect 60 nm Pareto defects) 3 4 # defects pareto ( 65 nm defects) 9618 defects 9618 defects- SC1 or dil Slurry NHball 3 Silica No cleaning rganic on Si 3 N 4 # defects pareto 150 (>= 60 nm defects) defects Slurry ball cluster Slurry ball clusterslurry ball Silica 200 rganic SC #A 210 # 0-10 AG 100 #1 SC-1 SC1 AG-#2 210 AG 210 #3 #A AG 210 #4 # Si 2 ER Review efect Pareto # defects pareto pareto (>= 65 ( nm 65 nm defects) defects) 250 slurry ball slurry cluster oxide organic-silica organic AG-#1 100 SC-1 SC1 AG-#2 210 AG-#3 210 #A AG-#4 210 # 210 P3 buff 16 PC AG- Series show improved performance over SC-1 on all substrates ER Review efect Pareto # defects pareto (>= 100 nm defects) # defects # defects pareto pareto (>= ( nm nm defects) defects) Slurry ball Slurry ball Slurry cluster Slurry cluster xide xide rganic rganic AG-#1 100 AG-# AG-#3 #A 210 AG-#4 # 210 P3 uff #A 210 # 210 P3 uff

17 EFECTIVITY CRRELATE T CHARGE REPULSIN ETEEN SILICA PARTICLES q 1 q 2 r Coulomb s Law F = kq 1 q 2 /r 2 Additive increases negative charge on particle surface 1. hite, M. L. et al, Materials Research Society Symposium Proceedings Volume 991Issue Advances and Challenges in Chemical Mechanical Planarization Pages Journal Hegde, Sharath; abu, S. V. Electrochemical and Solid-State Letters (2004), 7(12), G316-G3183. hite, M. L. et al. Mat. Sc. For E04-07 (2010).

18 (A/min) TITANKLEAN PERR AN SELECTIVE ETCH APPLICATINS Application: vs. TiN selective etching /TiN Etch controllable etchant TiN ER(A/min) ER(A/min) /TiN etching TiN Si substrate Gate oxide uried ordline Formation x 8x 12x Challenge and Requirements: Control selectivity of TiN/; compatible with various dielectric materials Etch rate controlled through selective Inhibitors * * * etter Inhibitors 18

19 CNCLUSINS Proper selection of Cobalt inhibitors and complexers can virtually eliminate cobalt corrosion Certain cobalt cleaning additives improve defectivity on cobalt Additives have been found that remove and disperse organic residue from silicon nitride after CMP Tungsten etch rate and corrosion can be controlled through the proper selection of inhibitors 19

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