| AVS 60th International Symposium and Exhibition | |
| Thin Film | Tuesday Sessions |
| Session TF-TuA |
| Session: | High Throughput ALD |
| Presenter: | S.F. Nelson, Eastman Kodak Company |
| Authors: | S.F. Nelson, Eastman Kodak Company C.R. Ellinger, Eastman Kodak Company L.W. Tutt, Eastman Kodak Company |
| Correspondent: | Click to Email |
In this talk we describe our approach to thin-film electronics using spatial atomic layer deposition (SALD). ALD has long been known for producing dense conformal films of conductors, insulators, and semiconducting layers from a limited set of precursors. However, in the more common vacuum- and chamber-based ALD processes, the deposition speed has generally been limited. In contrast, the SALD deposition process can be relatively fast. The coating takes place at atmospheric pressure in a localized region of a coating head, with no enclosure except that produced by gas isolation curtains, and thus without any pumping cycles.
Focusing on the field of metal oxide semiconductor thin-film transistors (TFTs), we have demonstrated that SALD produces high quality planar thin film transistors. TFTs with aluminum oxide for the insulator and zinc oxide (ZnO) for the semiconductor have high on/off ratios, and good uniformity of the deposited layers for deposition temperatures at and below 200°C. We show that the regime of fast ALD cycles accessible by SALD produces particularly good performance.
Patterning and alignment of transistors on flexible substrates can present a challenge, especially for short channel lengths. We have investigated novel vertical device architectures enabled by the conformal nature of SALD deposition that unite high performance with generous alignment and resolution requirements. With self-aligned sub-micron channel lengths, these devices demonstrate remarkable current-carrying capability at low voltage.
Finally, we will present a “patterned-by-printing" technique for SALD-grown transistors. By printing an inhibitor ink on the surface, the growth of aluminum-doped ZnO (conductor), aluminum oxide (insulator), and ZnO (semiconductor) can be limited to selected areas of the substrate. The process produces TFTs with the same excellent performance as lithographically patterned TFTs, with high yield, and rapid throughput.
In summary, we will present a range of opportunities in the area of thin-film and “printed” electronics that are enabled by spatial ALD.