Ultra-low stress SiO₂ coatings by ion beam sputtering deposition

Abstract

High mechanical stress can affect the performance of multilayer thin film optical coatings, causing wavefront aberrations. This is particularly important if the multilayer stack is deposited onto thin substrates, such as those used in adaptive optics. Stress in thin film coatings is dependent on the deposition process, and ion beam sputtering (IBS) thin films are known to have high compressive stress. In the present work, we show that stress in IBS S i O 2 thin films can be reduced from 490 MPa to 48 MPa using high-energy O 2 assist ion bombardment during deposition while maintaining high optical quality. A comparison of the reduction of stress in S i O 2 deposited from oxide and metal targets is provided.

Ion-Beam Sputtering of NiOx Hole Transporting Layers for p–i–n Halide Perovskite Solar Cells

“…IBS can produce films with high uniformity and reduced surface roughness. 19 This is because the ion beam can more effectively sputter the target material, resulting in fewer defects and impurities in the deposited film. So far, such a technique has not been considered for HP PVs.…”

“…This results in improved film quality and a lower risk of substrate damage, especially for temperature-sensitive substrates. IBS can produce films with high uniformity and reduced surface roughness . This is because the ion beam can more effectively sputter the target material, resulting in fewer defects and impurities in the deposited film.…”

Determination of stress in thin films using micro-machined buckled membranes

“…18 Concerning silica, films with low stress (ranging from À490 to À48 MPa) and high optical quality were obtained by IBS using high-energy O 2 ion bombardment during deposition. 19 In 2005, the stress level of IBS silica and tantala thin layers in the HR coatings of the LIGO interferometer was determined by Netterfield et al before and after a postdeposition thermal treatment (annealing hereafter) was applied. 20 They showed that a tantala film can readily go from a compressive state to a tensile state after only moderate annealing, whereas the compressive silica films stress is slightly relaxed and remains compressive.…”