Perspective: S – ALD

Spatial Atomic Layer Deposition

Image: Thin film semiconductor wafer (L); Cross-sectional scanning electron microscope image of an Al₂O₃ ALD film with a thickness of 300 nm on a silicon wafer with a trench structure (R)

Thin films and specialised coatings have been the enabling technology for many ground-breaking innovations in modern life, including OLED screens, solar cells and battery technology. To make these products more efficient, expand their lifetime, or miniaturise them further, it is important that the thin film that is incorporated in the product, or is covering the product, is of a consistent and high quality. The deposition of thin films also has to happen at a sufficiently high rate to enable economically viable production at a cost price which can facilitate wide-scale adoption. Current technology has to trade-off high production throughput with high quality and conformity of the film.

Solving this has the ability to unlock transformational applications in several next generation innovations such as:

1. Energy storage: Next generation solid state lithium batteries (with potentially 3x the lifespan, 3x the energy density and 1/6 the charge time of current cells)
2. Flexible electronics: Thin film coatings can coat flexible substrates such as flexible OLED displays, wearable electronics and bendable sensors that can be used in various applications such as foldable phones, wearables and car windscreens.
3. Solar power: Coatings for next generation solar cells such as perovskite solar cells that offer a step change in efficiency, cost and applications (a perovskite tandem cell offers a theoretical efficiency limit of 43% vs 29% for silicon cells)
4. Barrier coating in packaging: Barrier coatings such as ultra-thin moisture barrier coating in recyclable food and beverage packaging, eliminating plastics and widening the application of carton packaging.
5. Biomedical applications: Thin film biocompatible coatings on medical implants, devices, and diagnostic tools can enhance biocompatibility, reduce friction, and prevent bacterial adhesion, resulting in improved patient outcomes and device longevity.
6. Optical coatings: Thin film coatings can be used in anti-reflective coatings, optical filters, and mirrors for applications in optics, photonics, and solar panels.
7. Semiconductors: Thin, uniform coatings on packaging materials used in the semiconductor industry. These coatings can improve moisture resistance, thermal stability, and adhesion, enhancing the reliability and performance of semiconductor devices.