Large Area Sputter Deposition for Metal Oxide TFT Applications using Rotary Cathode Technology

Transcription

1 Large Area Sputter Deposition for Metal Oxide TFT Applications using Rotary Cathode Technology Marcus Bender R&D PVD Display Applied Materials FPD International China, Beijing September 11 th, 2013

2 Trends in Display Technology Ultra Large Displays Uniform and Stable, High Mobility TFT with simple Structure and low Manufacturing Costs! Slim Bezel Design High Refresh Rate (3D) Ultra High Resolution OLED TV Low Power Consumption New Requirements for Backplane Performance 2

3 Rotary Target Technology Excellent Cooling, Low Surface Temperature, Enabling high DR Racetracks Tmax ~ 80 C High Material Utilization TU ~ 80% Rotary Target AKT PiVot TM No Nodule Formation No Redeposition Zones New 80% 3

4 Uniform IGZO: Ion Bombardment Control µpcd Mura free IGZO

5 Excursion: Oxygen Ion Bombardment Reactive Sputtering Oxygen creates energetic and highly directional ion bombardment locally changing layer properties during growth TOF: Dominant Species O - Ions 1m between Detector and Source Bombardment Directions O - Ions always leaving the target surface perpendicular Planar: No control of directions, changing with target lifetime Rotary: Geometry constant, no change over lifetime O - Ion Trajectories: Planar vs. Rotary Tominaga, Thin Solid Films 1999 De Gryse, Thin Solid Films

6 PiVot: Ion Bombardment Control Two Concepts for unique Magnet Motion in PiVot: Perfect wobbling (PW) Magnet movement sweeps plasma across substrate Split sputter mode (SSM) Superposition of two sinusoidal profiles Widely spread Bombardment exposure across substrate Minimize Bombardment Impact (large angle, reduced energy) 6

7 µpcd: Correlations with IGZO TFT Reported direct correlation between µpcd measurement and TFT performance (by Kobelco) TFT μ-pcr (peak reflectivity signal) proportional to the carrier density and carrier mobility μ-pcd lifetime is characteristic to the recombination process of carriers, depending on quality of the IGZO µpcr correlation with TFT stability expected Kobelco, APL

8 Uniform IGZO: Tuning µpcr profiles Two routes towards more uniform reflectivity profiles Ion Bombardment Control Energetic oxygen ion bombardment locally increasing microwave reflectivity Magnet movement improving as depo non-uniformities PiVot can eliminate target imprints IGZO Post Annealing As depo non uniformities in µpcr can be reduced by annealing µpcr 4.8% after annealing 4.7% THK uniformity 8

9 Uniform IGZO: Gen8.5 horizontal µpcd scans Local Unif. 16% No Magnet Movement Local Unif. 12% Unif. 40% Unif. 20% Optimized Magnet Unif. < 5% Movement Unif. 10% Local Unif. << 5% Local Unif. << 5% Both, lifetime and amplitude homogeneity significantly improving by applying and optimizing magnet movement 9

10 Mura Free IGZO from PiVot Two kinds of mura known from PVD IGZO deposition Target Pitch Mura Reported Minimized Vth differences Vth difference with between correlationand to target in front positions of target for competitor system Bond Gap / Target Tile Mura No increase in peak reflectivity in front of bond gap area Data shows no target tile mura for IGZO rotary targets 2x IGZO rotary target at 60% Utilization 4 TFTs for each position Bond gap Bond gap Mura free IGZO Backplane Arai, Sony Corporation, SID

11 Stable IGZO TFT: PVD Al 2 O 3 performance

12 PVD Al 2 O 3 : Advanced Barrier Layer Significant Stability Improvement of IGZO TFT reported Arai, Sony Corporation, SID 2010 Challenges: Low deposition rate, slow etch 12

13 PVD Al 2 O 3 Performance Gen8.5 Thickness Thickness uniformity Breakdown voltage Density Deposition rate Refractive 550 nm Uniformity refractive index WER (DHF) Status Å ±9.0% (Gen 8.5, wobbling) ~ 2-3 MV/cm g/cm³ Å/min ~ ± 1 % (Gen 8.5, wobbling) 40~140 Å/min (depends on po2) t unif = +/- 9.0% n 550nm = +/- 1.1% 13

14 Conclusion IGZO TFT emerging as a-si replacement for high resolution mobile applications and large scale high definition LCD and OLED TVs Rotary target technology combined with unique magnet movement enable uniform PVD IGZO deposition TFT performance uniformity, especially V on, suitable for LCD and OLED applications Fully reactive Al 2 O 3 process with metal-like uniformity achieved with rotary target array 14

15 Acknowledgements Special Thanks to: Evelyn Scheer Andreas Klöppel Jian Liu Hyun Chan Park Rodney Lim Dong Kil Yim Harvey You Hao-Chien Hsu and everybody contributing to AMAT Metal Oxide progress around the globe 15

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