| AVS 64th International Symposium & Exhibition | |
| Thin Films Division | Tuesday Sessions |
| Session TF-TuM |
| Session: | Advanced CVD and ALD Processing, ALD Manufacturing and Spatial-ALD |
| Presenter: | Paul Poodt, Holst Centre / TNO, Netherlands |
| Authors: | C. Frijters, Holst Centre / TNO, Netherlands F. van den Bruele, Holst Centre / TNO, Netherlands F. Grob, Holst Centre / TNO, Netherlands P. Poodt, Holst Centre / TNO, Netherlands |
| Correspondent: | Click to Email |
Atmospheric spatial ALD (sALD) is able to deliver high deposition rates while maintaining the advantages of conventional ALD, such as low defect density, high conformality and thickness uniformity. First industrial applications of Spatial ALD include passivation of c-Si solar cells and roll-to-roll manufacturing of flexible barrier foils. An emerging application for Spatial ALD are flat panel (OLED) displays. We have developed spatial ALD processes for making high mobility oxide semiconductors for the TFT backplane as well as thin-film encapsulation for the OLED front plane. As today’s displays are fabricated using glass panels in the order of several square meters, a remaining challenge is the development of large-area sALD deposition technology that is able to combine high throughput with uniform performance across large areas.
As an intermediate step between the lab and the display fab, we have installed a large area Spatial ALD sheet-to-sheet tool which can handle up to 400x325 mm2 sized substrates, able to deposit uniform films across a deposition width of 300 mm. The whole tool is operated under an atmospheric but inert N2 atmosphere. We will present the basic deposition performance of the tool, where large-area thickness non-uniformities of less than 1% have been achieved for alumina on glass. Furthermore, we will demonstrate excellent compositional uniformity for binary oxides.
One of intended applications is thin-film encapsulation of OLED devices. In order to test the encapsulation performance of the films deposited by the large area spatial ALD tool, we deposited single layer and double layer alumina films, in combination with printed organic planarization layers, on PET foils laminated on 325 mm x 325 mm glass panels. The encapsulation performance was tested under damp-heat conditions. The deposited encapsulation stacks show excellent results, with virtually no visible defect appearing after more than 1000 hrs. at 60 oC 90 %RH, corresponding to a potential device lifetime of at least 2.5 years. These results demonstrates the potential of spatial ALD for manufacturing large-area OLED devices.