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Due to the perfection of the nanofabrication in nanotechnology and nanoscience, ice lithography (IL) by patterning ice thin-films with a focused electron beam, as a significant derivative technology of electron beam lithography (EBL), is attracting growing attention, evoked by its advantages over traditional EBL with respects of

X-ray microscope as an important nanoprobing tool plays a prevailing role in nano-inspections of materials. Despite the fast advances of high resolution focusing/imaging reported, the efficiency of existing high-resolution zone plates is mostly around 5% in soft x-ray and rapidly goes down to 1%–2% when the resolution approaches 10 nm. It is well known that the rectangular zone shape, beamstop, limited height/width ratios, material absorption of light and structural defects are likely responsible for the limited efficiency. Although zone plates with Kinoform profile are supposed to be efficient, progress for achieving both high resolution (5%) have hardly been addressed in soft x-ray. In this work, we propose a compound Kinoform/Fresnel zone plate (CKZP) by combing a dielectric Kinoform zone plate with a 15 nm resolution zone plate. Greyscale electron beam lithography was applied to form the 3D Kinoform zone plate and atomic layer deposition was carried out to form the binary zone plate. Optical characterizations demonstrated 15 nm resolution focusing/imaging with over 7.8% efficiency in soft x-ray. The origin of the efficiency improvement behind the proposed compound lens is theoretically analyzed and discussed.

X-ray microscope as an important nanoprobing tool is expected to play a powerful role in nano-inspections of materials. Despite the fast advances of high resolution focusing/imaging reported, the diffraction efficiency of existing binary zone plates as the lenses in the microscope is mostly around 5% in practice and rapidly goes down to 1-2% when the resolution approaches 10 nm, failing its applications in advanced scientific research. Zone plates with Kinoform profile are supposed to be high efficient, little progress for achieving both high resolution and high efficiency has been reported. The conflict between the resolution and the efficiency in X ray optics has become a long-lasting bottleneck in the further development of X-ray microscope. Based on our earlier success in developing high efficiency Kinoform zone plates by greyscale electron beam lithography, we proposed, in this work, a new zone plate structure by combing a dielectric Kinoform zone plate with an atomic layer deposited HfO2 zone plate to achieve high resolution focusing/imaging with high efficiency. Beam propagation method was applied in designing and optimizing Kinoform shapes of the zones, greyscale and/or binary electron beam lithography was carried out for generating both 3D Kinoform as well as rectangular zones with aspect ratio of 23/1 in dielectric resist, and finally high-quality atomic layer deposition of HfO2 was conducted to form the 15-nm wide outermost zone. Optical characterizations by an in-house developed soft X ray microscope demonstrated 15-nm resolution focusing/imaging with over 7% efficiency, which is the highest with such a resolution as far as our awareness. The origin of such an improvement behind the proposed novel lenses is interpreted by our BMP calculation results and the comparisons with existing performances by other reports in literature was discussed.

Despite self-supporting ultrathin Si membranes are already being widely applied, its thickness control in micron scale still remains a big challenge for delicate systems such as micro-opto-electro-mechanical systems and silicon-based X-ray diffractive optics. Instead of using the conventional wet etch rate of Si to monitor the membrane thickness, this work has developed a reliable approach to control the membrane thickness in the precision of micrometer order by using an optical detection hole with high precision depth, which decides the membrane thickness in the Si thinning process. The wet etch rate is first optimized to ensure the fundamental condition for such a thickness control. Furthermore, the membrane surface roughness is greatly reduced by optimizing the additive ethanol concentration in the KOH etchant, based on the investigation results for the origin of the membrane surface roughness. Using the proposed etching and thickness-monitoring method, self-supporting micron thick Si (100) membranes with the surface roughness of

For high quality imaging of materials in nanoscale by hard X-ray optics, high resolution lenses with high focusing/imaging efficiency are needed. Refraction based conventional Kinoform lenses with 1D linear configuration in Si has been attempted for decades, but there has still been no sign of success due to the enormous difficulty in fabrication. This paper proposes a novel configuration of golden Kinoform lenses with round shape on a plate, in which each zone maintains the typical 3D parabolic profile as seen in the traditional 1D counterpart. The major focus in this work is on the generation of the 3D profile in e-beam resist through greyscale electron beam lithography (EBL) as the template for the golden Kinoform lens. Systematic study of the greyscale lithography conditions, including the comparisons of resists, developers and charge distributions, has been conducted by using Monte Carlo simulation as well as e-beam lithography. Initial results have been achieved for replicating the desired 3D profile of the golden Kinoform lens in the resist. Using the generated profile in resist as templates, the golden Kinoform lens with 200 μm diameter and 3.5 μm height has been successfully fabricated, for the first time, which will hopefully replace the existing Fresnel zone plates for hard X-ray imaging with high resolution and high efficiency.