To explore the potential of achieving low-stress and high-reflectance Mo/Si multilayers deposited by conventional magnetron sputtering with bias assistance, we investigated the effects of varying Ar gas pressure, substrate bias voltage, and a bias-assisted Si ratio on the stress and extreme ultraviolet (EUV) reflectance of Mo/Si multilayers. To reduce the damage of ion bombardments on an Si-on-Mo interface, only the final part of the Si layer was deposited with bias assistance. Bias voltage has strong influence on the stress. The compressive stress of Mo/Si multilayers can be reduced remarkably by increasing bias voltage due to the increase of Mo-on-Si interdiffusion and postponement of Mo crystallization transition. Properly choosing gas pressure and a bias-assisted Si ratio is critical to obtain high EUV reflectance. Appropriately decreasing gas pressure can reduce the interface roughness without increasing interdiffusion. Too much bias assistance can seriously reduce the optical contrast between Mo and Si layers and lead to a remarkable decrease of EUV reflectance. Thus, by appropriately choosing gas pressure, bias voltage, and a bias-assisted Si ratio, the stress values of Mo/Si multilayers can be reduced to the order of $-100\mathrm{MPa}$ with an EUV reflectance loss of about 1%.

An inversion method based on a genetic algorithm has been developed to control the lateral thickness gradients of a Mo–Si multilayer deposited on curved substrates by planar magnetron sputtering. At first, the sputtering distribution of the target is inversed from coating thickness profiles of flat substrates at different heights. Then, the speed profiles of substrates sweeping across the target are optimized according to the desired coating thickness profiles of the primary and secondary mirrors in a two-bounce projection system. The measured coating thickness profiles show that the non-compensable added figure error is below 0.1 nm rms, and the wavelength uniformity across each mirror surface is within $\pm 0.2\%$ P-V. The inversion method introduced here exhibits its convenience in obtaining the sputtering distribution of the target and efficiency in coating iterations during process development.

We present a dual-layer hafnium dioxide (HfO₂) grating capable of full-color modulation in the visible spectrum by leveraging the magnetic dipole resonance induced by the lower-layer HfO₂ grating, while the upper-layer HfO₂ grating serves as a refractive index matching layer to effectively suppress high-order Mie resonances at shorter wavelengths. The HfO₂/HfO₂ grating exhibits a significantly larger distribution area in the CIE 1931 chromaticity diagram compared to the HfO₂ grating. Furthermore, the structural color saturation closely approximates that of monochromatic light. Under varying background refractive index environments, this structure consistently exhibits high-quality structural color. However, the hue of the structural color undergoes alterations. When the polarization angle is below 20°, the saturation of the acquired structural color remains remarkably consistent. However, exceeding 20° results in a significant degradation in the quality of the structural color. This study demonstrates the promising potential for diverse applications, encompassing fields such as imaging and displays.