CMPUG 2002 Nitrogen-Based Slurry Development for Copper/Low-k (SiLK TM ) Integration June 5, 2002 Lily Yao, Bob Small,Ph.D, KZ Kadowaki, Srini Raghavan, University of Arizona EKC == CMP It doesn t get any planar than that. sm E N A B L I N G T E C H N O L O G Y C O M M I T T E D T O Q U A L I T Y 2002 EKC Technology, Inc.
AGENDA Introduction * Current Cu/SiLK Integration * Cu/SiLK CMP Process * Nitrogen-based slurry Experimental Set-up * Polisher, Pads, Measurement Equipment, Wafers and Slurries Results Conclusion *Step 2 Hydroxylamine/Silica-Based Slurry for Cu/SiLK (porous and regular) Applications a. High Selectivity b. Low/Non Selectivity * Copper and SiLK Surface RmS, FTIR After CMP
Copper/SiLK Integration Scheme Cu TaN SiC SiC SiO 2 SiLK SiO 2 Si Structure with a cap layer The final stop layer is at ILD layer With Cap layer: Stop at SiO 2 Without Cap layer: Stop at Low-k layer
Copper/SiLK Integration CMP Process Cu TaN SiO 2 SiC SiLK SiC SiO 2 Si Step 1 Step 2 Phase-I Phase-II Selectivity Non/Low Cu:TaN = >20:1 Selectivity Stop at barrier layer Single Step Stop at SiO 2 /SiLK layer Single - Phase
Nitrogen-Based Slurry Development for Copper CMP Hydroxylamine Reduction Potentials & Reaction Paths OXIDATION REDUCTION BASIC 0.15 0.73 0.1 0.01 NO2 0.94-3.04 NH2OH N2H4 NH 3 NO 3 N2O N2 0.94 HNO 3 1.77-1.87 NH 3OH + N2H5 + NH 4 + ACIDIC 1.297 1.41 1.275 Reference: Dr. Srini Raghavan Copper Removal in Hydroxylamine Based Slurries 7th International Symposium
Current EKC Cu Slurries Hydroxylamine-Based Slurry Development for Copper CMP Oxidizer Abrasive Application Cu Phase-I Hydroxylamine Based Al 2 O 3 Removal Cu layer Cu Phase-II Hydroxylamine Based Colloidal Silica (Supply A) Removal TaN with a high selectivity Hydroxylamine Based Colloidal Silica (Supply A & B) Removal Cu, TaN, TEOS at a same speed (non selectivity) Single Phase Hydroxylamine Based Al 2 O 3 Removal Cu, barrier and stop at ILD layer
Experimental Set-up * Polisher: IPEC 472; Nitrogen-Based Slurry Development for Copper/Low-k (SiLK TM ) Integration *Polishing Pads: Rodel IC1000 k-groove/suba IV or Politex Embossed polishing pads * Measurement Equipment: Cu and TaN Thickness: CDE ResMap 176 TEOS Thickness: KLA-Tencor 650 SiLK Thickness: KLA-Tencor 650 and Gaertner Ellipsometry SiLK surface chemical change: BioRad FT-IR spectrometer (FTS175C) Cu Surface roughness: Digital Instrument AFP200 *Slurries: EKC Cu Phase-I and Phase-II oxidizers, EKC Cu Alumina and Silica Abrasives * Blanket Wafers: 200mm EP copper, TaN, TEOS and SiLK: V9-LC (porous), V9-HC (porous) SiLK-I (regular) SiLK*I (Ensemble).
SiLK Blanket Wafer Types Porous SiLK (V9-LC & V9-HC) Regular SiLK (SiLK-I) Regular SiLK Ensemble ES film Regular SiLK (SiLK*I) SiLK+Ensemble Integrated Stack
Alumina Based Slurry for SiLK Film Sheet Film Removal Rate IPEC 472 Polisher / IC1000 k- grv/suba IV Pad 5000 Process (soft landing) Slurry mixing (v/v/v): 4000 2 psi polishing pressure 50% Cu Oxidizer, Film MRR, A/min 3000 2000 70 rpm platen speed 25% DIW 75 rpm carrier speed 25% Al 2 O 3 (5% solids) 200 ml/min slurry flow 1000 0 Cu, 5 psi Cu, 2psi TaN Blanket Wafers TEOS SiLK*I(ES) RESULTS 1) SiLK film RR was 60% lower than the TEOS. TEOS RR = 195Å/min, SiLK RR = 50 Å/min 2) Both Cu and SiLK Rms reduced after CMP. Pre-CMP: Cu>>30Å, SiLK=6.5 Å. Post CMP Cu = 7.3 Å, SiLK = 5.6 Å
Silica Based Slurry for High Selectivity Application Mean Removal Rate vs. Cu-II Formulation RESULTS Sheet Film MRR, A/min 1500 1200 900 600 300 1) Selectivity of Cu:TaN:SiLK = 1: 3-11: <1 2) TaN removal rate is related to Cu-II oxidizer concentration as expected. 3) Reducing either oxidizer or abrasive will reduce SiLK removal rate. 4) Post CMP Rms of Cu and SiLK was 5-10 Å. Cu 0 A B C D Cu-II Nitrogen-Silica Based Slurry Formulation TaN TEOS SiLK*I (ES) Formu Slurry Formulation Oxidizer Silica Solids Post CMP Rms (A) Abrasive Type Cu SiLK A 50% 5% 7 5 IPEC 472 Polisher / Politex Embossed Pad Process: 3 psi polishing pressure, 50-70 rpm platen speed B 20% 5% Abra-I 10 7 C 50% 1% 9 6 D 50% 5% Abra-II 7 5 55-75 rpm carrier speed, 200 ml/min slurry flow no conditioning in between
Silica Based Slurry for High Selectivity Application High Selectivity Slurry for SiLK Film High Selectivity Slurry for SiLK Film 600 600 Sheet Film MRR, A/min 500 400 300 200 100 0 Slurry Type A Slurry System Cu TaN TEOS Porous-LC Porous-HC SiLK-I SiLK*-I SiCN Sheet Film MRR, A/min 500 400 300 200 100 0 Slurry T ype E Slurry System Cu TaN TEOS Porous-LC Porous-HC SiLK-I SiLK*-I SiCN Target: Lower SiLK Film MRR * Original high selectivity slurry (Type A, Cu:TaN:Oxide = 1: 5: 1) shows a higher porous SiLK MRR * Slurry Type E reduced porous SiLK MRR efficiently. Process Set up: IPEC 472 Polisher / Politex Embossed Pad Process: 2 psi polishing pressure, 70 rpm platen speed,75 rpm carrier speed, 200 ml/min slurry flow.
Silica Based Slurry for Low/Non Selectivity Non Selectivity Slurry for SiLK Film RESULTS Sheet Film Removal Rate, A/min 600 500 400 300 200 100 Cu TaN TEOS Porous-LC Porous-HC SiLK-I Low/Non Selectivity slurry (Type C and D) showed similar TaN MRR to Cu and Oxide. They also showed a good control for SiLK porous film as well as regular SiLK film. SiCN MRR is similar to oxide 0 Slurry Type F Slurry System Slurry Type G SiLK*-I SiCN Process Set up: IPEC 472 Polisher / Politex Embossed Pad Process: 2 psi polishing pressure, 70 rpm platen speed 75 rpm carrier speed, 200 ml/min slurry flow
SiLK*I (Ensemble) Film MRR vs. Polishing Pressure SiLK*I (ES) Film MRR, A/min 4000 3000 2000 1000 0 SiLK*I (ES) Film MRR vs. Polishing Pressure 1 2 3 4 5 Down Force, PSI Polishing Removal SiLK*I (ES) Pressure Rate Rem NU (PSI) (A/min) % 1 15 n/a 2 40 n/a 3 174 4 1367 15.8 5 3576 6.5 Other Parameters IPEC472 polisher Politex reg pad 90 rpm pp 95 rpm cs 200 ml/min sf Slurry Type F RESULTS SiLK*I (ES) film has a lower removal rate with lower polishing pressure.
SiLK Surface FTIR Before and After CMP 1.4 Porous (V9-LC) SiLK Film FTIR Pre vs. Post CMP Conclusion Adsobence (Stacked) 1.2 1 0.8 0.6 1) SiLK Porous and SiLK (ES) Film have no changes on FTIR before and after CMP 2) SiCN Film has no changes on FTIR before and after CMP 0.4 SiLK (ES) Film FTIR Pre vs. Post CMP V9-LC-Pre 1.4 0.2 3998 1.2 3612 3227 2841 2455 2069 1683 1297 Wavenumber (cm-1) SiCN Film FTIR Pre vs. Post CMP 911 525 Type A Type B Type C Type D Adsorbence (stacked) 1.2 1 0.8 0.6 1 0.4 Adsorbence (Stacked) 0.8 0.6 0.2 3998 3612 3227 2841 2455 2069 1683 Wavenumber (cm-1) 1297 911 525 SiLK*-I-Pre Type A Type B Type C Type D 0.4 0.2 3998 3612 3227 2841 2455 2069 Wavenumber (cm-1) 1683 1297 911 525 SiCN-pre Type B Type D
Copper and SiLK Surface After CMP Cu and SiLK Surface Finishing 15 12 RmS (Angstroms) 9 6 3 0 Pre A E F G Slurry System SiLK*I (ES) Cu 1) SiLK RmS was similar before and after CMP 2) Cu prerms was >30 A..
Conclusion: Nitrogen-Based Slurry Development for Copper/Low-k (SiLK TM ) Integration * Hydroxylamine-based slurry is compatible for Cu/SiLK (both porous and regular) CMP process. * With silica abrasive, the slurry can be designed for either a high selectivity or non-selectivity of Cu/TaN/Oxide and efficiently stop at SiLK layer. * No delaminating of SiLK films. * SiLK surface RmS and chemical composition were the same as pre-cmp. * Film removal non-uniformity and wafer profile are within the spec. * The new nitrogen-based slurries have the potential to reduce the COO.
Acknowledgements We would like to thank: Dow Chemical Ketan Itchhaporia, Michael Simmonds Don Frye EKC Technology Don Frey Philippe Chelle Mel Carter