Thin films manufacturing: going beyond the state of the art by plasma technology

Transcription

1 Thin films manufacturing: going beyond the state of the art by plasma technology Yves Creyghton, Andrea Illiberi and Fred Roozeboom Solliance/TNO, Eindhoven

2 2 Outline New challenges in thin film manufacturing Concept of plasma enhanced spatial ALD Plasma technology Application examples Summary of conclusions

3 New challenges in thin film manufacturing 3

4 New challenges in thin film manufacturing 4 Emerging applications have strict requirements on: Precise growth and thickness control High conformality / step coverage Good uniformity on large substrates Low substrate temperatures H. Knoops et al., in Handbook of crystal growth: thin films and epitaxy (2 nd ed.) (pp ), Elsevier

5 New challenges in thin film manufacturing 5 How to combine nano-scale engineering with up-scalability? Nano-scale engineering Interfaces Defects Nano-structure Conformality (3D) Up-scalability High throughput R2R or S2S Low cost Large area uniformity Low temperature Courtesy: CPI (UK)

6 Atomic layer deposition 6 Key features: Reactants (precursors) are pulsed into the reactor alternately and cycle-wise (A B A B..) Precursors react through self-limiting surface reactions A (sub-)monolayer of material deposited per cycle Deposition rate mm/day Courtesy: S. Elliot (Tyndall Institute)

7 ALD examples of nanometer dimension control 7 Defects (dust particles) encapsulation Area selective deposition Courtesy: W. Kessels (TU/Eindhoven) A.J. Clark (Univ. Maryland)

8 Plasma radical enhanced ALD H 2 O, O 2, H 2, NH 3 Key benefits: Reduced temperatures deposition on plastic foils Improved material properties : lower impurity, higher density Wider choice of chemical coating precursors: Highly stable precursors Metal and metal nitride depositions 8 O, OH, HO 2, N, H, NH Potential drawbacks: Reduced step coverage Surface damage by plasma ions and radiation Profijt et al., JVST-A Vol.29 (2011)

9 Spatial ALD hours become minutes 9 Spatial ALD deposition rates >1 nm/s Example: low temperature deposition of AlOx using TMA+H2O Slow water desorption very long N 2 purge times needed Problem solved by TMA + plasma in O 2 /N 2

10 Roll-2-roll spatial ALD 10

11 11 Commercial availability of plasma ALD ALD system Thermal Plasma-Enhanced Vacuum Spatial Available Available Atmospheric pressure Timesequenced Timesequenced Spatial NOT AVAILABLE NOT AVAILABLE

12 12 Proposed solution: Dielectric Barrier Discharge Plasma Requirements: Homogeneous and stable Direct and remote plasma sources are exchangeable Source materials chemically and dimensionally stable up to 350º C Industrial (economic) gases (N 2, fractions of O 2, H 2 O, H 2, NH 3, N 2 O) Low gas consumption, up-scalable from mm

13 Proof of principle ALD reactor 13

14 Know how for homogeneous, stable and cold plasma 14

15 Thin film metal oxide applications 15 Flexible CIGS module Flexible displays Courtesy: INM Leibniz Institute for New Materials

16 High-resolution large area displays From a-si:h to IGZO 16

17 thickness (nm) S-ALD of IGZO, growth 10 Thermal ALD InO x InZnO cycles No growth or nucleation delay Limited control of stoichiometry Plasma ALD ZnO Plasma ALD Main benefits: Lower substrate temperature Larger choice of precursors/materials Higher growth rates Improved materials properties DBD plasma source easy to upscale 17 InOx Challenges: Damage of the substrate Non-optimal conformality p Zn / p In H. Profijt et al., J. Vac. Sci. Technol. A (2011)

18 thickness (nm) Is remote plasma ALD sufficiently reactive (for IZO)? um distance 1 mm distance 2 mm distance exposure time (ms) N 22 flow (sccm) (slm)

19 Plasma technology roadmap Device demonstrators 19 Process research R2R Upscaling S2S Area selective deposition

20 20 Summary of conclusions Spatial Plasma ALD technology meets requirements: Effectiveness of remote plasma, no substrate damage Homogeneity and stability Contamination and recombination control Manufacturing scalability Application research program opens unique options for: Low temperature fast ALD on plastic foils New materials, control of layer composition Know-how transfer of plasma and chemical process technology Industry partner participation