LINX is a NWO-TTW perspective programme with the aim to apply various lensless imaging techniques, from ptychography to scatterometry, while using wavelengths in the EUV and Soft X-Ray regime. This programme is a collaboration with five largest Dutch universities and major (inter)national industry partners with a budget of ±4MEuro. The aim is to generate innovative metrology techniques relevant for the Dutch industry like ASML, TNO and Malvern PANalytical.

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Objective

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.

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Impact

Innovations in the semiconductor industry lead to smaller and more efficient integrated circuits. The production of the next-gen chips is not perfect, leading to defects in these chips. High resolution imaging, metrology and inspection tools are required in order to find these defects. LINX is taking the challenge to find methods with this problem in mind.

However, these methods are not just applicable for the semiconductor industry. 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.

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