LINX is developing lensless imaging with soft X-rays (SXR) hereby targeting a major technology development that is crucial for two exponents of the high-tech industry in the Netherlands: 3D-imaging of nanostructures in the semiconductor industry, where wafer metrology for lithography is one of the key enabling technologies; and advanced X-ray instrumentation for analysis of surfaces and materials.
These two industries are well represented in the Netherlands by ASML, which is the market leader in the area of lithography, and by Malvern/PANalytical, being a leading supplier in advanced X-ray instrumentation.
3D Metrology in Semiconductor Industry
The ambition of LINX is to image 3D nanostructures in ICs with a lateral resolution (in the wafer plane) of ultimately 1 nm, and with a perpendicular resolution of around 10 nm, for a depth of the structure of a few 100 nm at maximum. SXR lensless imaging is a unique technology that can offer the required resolution performance using coherent diffractive imaging (CDI) and ptychography. Coherent SXR sources with high brightness are suitable candidates for this purpose. HHG technology with sufficient flux for imaging has been demonstrated down to 10 nm wavelength, but a further reduction of the wavelength to the required lateral resolution of 1 nm, while achieving sufficient brightness, is currently not considered feasible. Therefore, LINX aims at extending ptychography to superresolution imaging (10x Abbe Limit), using a priori knowledge. For nanostructures in ICs, the prior knowledge is present since all structures are generated through lithographic imaging from a patterned mask. The use of prior knowledge of a sample is reminiscent of a similar approach in scatterometry as used in metrology of periodic structures.
X-Ray Analysis of Surfaces and Materials
The synergy between the developments in lensless imaging using coherent X-ray radiation and the current application portfolio of Malvern/PANalytical resides in the area of analysis of nanostructured materials, like catalists, solar cells and proteins. Malvern/PANalytical offers solutions for, amongst others, X-ray diffraction (XRD), including GI-SAXS (grazing-incidence small-angle X-ray scattering), and X-ray fluorescence (XRF). Some potential applications highly depend on coherent X-ray sources using techniques like ptychography or even ptycho-tomography. In this application area, the key-research questions are two-fold: (1) the applicability of lab-based table-top SXR sources in X-ray instrumentation for material analysis, and (2) the complimentarity of ptychography based approaches for the application space that is currently covered by (GI)SAXS.