Eric Dickey, William A Barrow, Bryan Danforth, Lotus Applied Technology, Hillsboro, Oregon
Atomic Layer Deposition (ALD) is now a well-established process broadly used in the manufacture of leading-edge semiconductor chips. ALD is required for this application due to its high level of precision and ability for conformal deposition of pinhole-free coatings on complex surfaces. These same coating attributes are highly desirable in other applications, such as thin film encapsulation, on the large area substrates used in the display and photovoltaic industries. But to date, scaling of ALD processes to such large substrates, with sufficient throughput and at the low cost required for these applications, has been elusive. In this work, a novel Spatial Plasma Enabled ALD (S-PEALD) process is demonstrated that offers the economic scalability of ALD to these large area substrates. The use of a simple DC plasma source, enabled by the use of spatial processing, allows plasma generation over the multi-meter distances required for these substrate sizes. Meanwhile, a novel method for spatial precursor separation provides the means to utilize a simple, compact, and rapidly moving coating head for executing the ALD cycle. In combination with a mixed oxide barrier material, a process is demonstrated that provides a path to the in-line deposition of OLED-quality barrier coatings on multi-meter substrates, with a takt time of less than one minute.