1. Spatial ALD
Ismo Heikkinen

2. From Temporal to Spatial ALD
ALD has unique advantages: precise film thickness control, highly conformal coatings, low T processing…
…but batch ALD is slow
Solution: separate the precursors in space rather than in time
Poodt, P et al. Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition. J. Vac. Sci. Tech. A, 2012, 30,
Muños-Rojas D.; et al. Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics. Mater. Horiz. 2014, 1, 314.

3. How does Spatial ALD work?
In SALD the sample is moved under precursor and purge zones to reproduce the ALD cycle
Cycle time notably reduced, film quality maintained
5-10 times faster than temporal ALD
Poodt, P et al. Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition. J. Vac. Sci. Tech. A, 2012, 30,
Muños-Rojas D.; et al. Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics. Mater. Horiz. 2014, 1, 314.

4. Spatial ALD systems
Poodt, P et al. Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition. J. Vac. Sci. Tech. A, 2012, 30,
Maydannik P.S. et al. Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications. J. Vac. Sci. Tech. A, 2014, 32,

5. SALD in practice Photovoltaics: Encapsulation and moisture barriers:
Passivation of c-Si solar cells with Al2O3
Buffer layers for CIGS solar cells
Antireflection coatings
Encapsulation and moisture barriers:
Flexible electronics
OLEDs
Packaging
…and emerging applications
Illiberi A. et al. Spatial Atmospheric Atomic Layer Deposition of AlxZn1-xO. ACS Appl. Mater. Interfaces 2013, 5,
Choi H. et al. Fast spatial atomic layer deposition of Al2O3 at low temperature (<100 °C) as a gas permeation barrier for flexible organic light-emitting diode displays. J. Vac. Sci. Tech. A, 2016, 34, 01A121.
Illiberi A. et al. Spatial Atmospheric ALD of functional layers for CIGS Solar Cells. ECS Transactions, 2015, 69 (7),

6. Why go Spatial? Conclusions
Advantages
High throughput in nm/s for high-quality films
Efficient precursor utilization (growth only on the substrate)
Disadvantages
Limited to 2-dimensional substrates (glass, Si wafers, plastic and metal sheets…)
Not so many processes available as with temporal ALD

7. Questions are welcome!

8. Information slides - Basics of Spatial ALD
Temporal ALD is financially viable in large batches, but:
Sensitive samples (such as OLEDs) might be damaged by long preheat times
A big amount of expensive samples in one big batch is a huge risk
Spatial ALD reduces these risks and increases the throughput in nm/min
Materials deposited with Spatial ALD: Al2O3, TiO2, ZnO, ZnS, Al:ZnO, ZnOxSy…
Poodt, P et al. Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition. J. Vac. Sci. Tech. A, 2012, 30,
Muños-Rojas D.; et al. Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics. Mater. Horiz. 2014, 1, 314.

9. Basics of Spatial ALD Spatial ALD devices are based on:
Spatially separated precursor zones
Moving substrate and/or a moving gas distribution head
Inert gas barrier between half-reaction zones to prevent the mixing of precursors
No need for purging a reactor chamber -> much faster ALD cycles than in temporal ALD
From tens of seconds to less than one second
SALD 5-10 times faster than temporal ALD
Limitation to 2D materials is a big downside
Muños-Rojas D.; et al. Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics. Mater. Horiz. 2014, 1, 314.
Choi H. et al. Fast spatial atomic layer deposition of Al2O3 at low temperature (<100 °C) as a gas permeation barrier for flexible organic light-emitting diode displays. J. Vac. Sci. Tech. A, 2016, 34, 01A121.

10. How does Spatial ALD work?
Poodt, P et al. Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition. J. Vac. Sci. Tech. A, 2012, 30,

11. Different approaches to SALD
Rotary SALD
Sample is e.g. a Si wafer which rotates and is sequentially exposed to precursors
Produces a ring-shaped thin film coating
View from top of the reactor ->
Poodt, P et al. Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition. J. Vac. Sci. Tech. A, 2012, 30,

12. Different approaches to SALD
Roll-to-roll SALD
Flexible substrate is transported through the coating area
Can have a rotating gas injection system which makes the ALD cycle faster
Applications in encapsulating flexible electronics and functionalizing textiles
Maydannik P.S. et al. Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications. J. Vac. Sci. Tech. A, 2014, 32,

13. Different approaches to SALD
Close proximity SALD
Distance between the gas injector and the substrate in the order of 100 μm
Possibility to accurately coat small areas
and detailed structures
Muños-Rojas D.; et al. Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics. Mater. Horiz. 2014, 1, 314.
Muñoz-Rojas D. et al. High-speed atmospheric atomic layer deposition of ultrathin amorphous TiO2 blocking layers at100 ° C for inverted bulk heterojunction solar cells. Prog. Photovolt. Res. Appl. 2013, 21,

14. Different approaches to SALD
SALD for wafers, sheets and glass substrates
From one to few mm between the sample and the gas injector
Large substrate size is possible, e.g x 500 mm2
Choi H. et al. Fast spatial atomic layer deposition of Al2O3 at low temperature (<100 °C) as a gas permeation barrier for flexible organic light-emitting diode displays. J. Vac. Sci. Tech. A, 2016, 34, 01A121.
Beneq Oy, Espoo, Finland. Size matters (and speed too), HIGH-THROUGHPUT THIN FILM COATING WITH LARGE-AREA SPATIAL ALD EQUIPMENT. Blog post, Available: Cited

15. References
Muños-Rojas D.; et al. Spatial atmospheric atomic layer deposition: a new laboratory and industrial tool for low-cost photovoltaics. Mater. Horiz. 2014, 1, 314.
Poodt, P et al. Spatial atomic layer deposition: A route towards further industrialization of atomic layer deposition. J. Vac. Sci. Tech. A, 2012, 30,
Illiberi A. et al. Spatial Atmospheric Atomic Layer Deposition of AlxZn1-xO. ACS Appl. Mater. Interfaces 2013, 5,
Choi H. et al. Fast spatial atomic layer deposition of Al2O3 at low temperature (<100 °C) as a gas permeation barrier for flexible organic light-emitting diode displays. J. Vac. Sci. Tech. A, 2016, 34, 01A121.
Maydannik P.S. et al. Roll-to-roll atomic layer deposition process for flexible electronics encapsulation applications. J. Vac. Sci. Tech. A, 2014, 32,
Illiberi A. et al. Spatial Atmospheric ALD of functional layers for CIGS Solar Cells. ECS Transactions, 2015, 69 (7),

16. References
Muñoz-Rojas D. et al. High-speed atmospheric atomic layer deposition of ultrathin amorphous TiO2 blocking layers at 100 ° C for inverted bulk heterojunction solar cells. Prog. Photovolt. Res. Appl. 2013, 21,
Beneq Oy, Espoo, Finland. Size matters (and speed too), HIGH-THROUGHPUT THIN FILM COATING WITH LARGE-AREA SPATIAL ALD EQUIPMENT. Blog post, Available: Cited