Atomic layer deposited corrosion barrier solutions have been of high interest lately in the semiconductor industry. The main driver for this has been the need to protect plasma etching tools used in several manufacturing steps from self-damage and contamination. Traditionally, thick ceramic coatings applied with spray coating have been used but these techniques suffer from low conformality, which makes it unable to protect parts with complex geometries like showerheads. [1]

The most sought-after materials, like Y₂O₃ and YF₃ are very etch resistant [2], but are difficult to scale to large ALD tools, while retaining good conformality and repeatability [3]. YF₃ especially has been problematic from a tool maintenance and health & safety perspective as available processes involves HF as a reaction by-product.

We present process development and scale up results from a new precursor (Y-Beta’, Air Liquide), which can produce pure YF₃ films using O₃ as co-reactant. The process is scaled up to Picosun P-1000 class tool with maximum usable chamber volume 0.2 m³, which can be used to deposit several full-sized showerheads. The process can reach a GPC of >1 Å and cycle time 20 s. At temperatures below 300°C, Chip-2-Chip uniformity of <10 % over the whole volume of the chamber is achieved. The process is compatible with macroscopic high aspect ratio structures, boasting a CEAR50 (coated equivalent aspect ratio [5]) value of 146. The compositional purity of the resulting films was determined with ToF-ERDA along with structural characterization by XRD.

The general ALD process portfolio has been wanting for a simple, convenient, and robust alternative for YF₃ deposition in addition of the two existing ones [4,6]. This new precursor answers directly to this need by allowing the YF₃ to be deposited in industrial scale without HF.

[1] Shih (2012), ISBN: 978-953-51-0467-4

[2] Kim et al. (2011), doi:10.1111/j.1551-2916.2011.04589.x

[3] Abdulagatov et al. (2019), doi:10.1134/S1063739719010025

[4] Wallas et al. (2018), AVS 65th International Symposium & Exhibition

[5] Cremers et al. (2019) doi.org/10.1063/1.5060967

[6] Pilvi et al. (2008), doi:10.1002/cvde.200806721