With the breakthrough of EUV lithography, the spatial scale in semiconductor manufacturing has decreased to well below the resolution limits of traditional optical metrology tools. This is why XUV light sources become more and more relevant for novel at-resolution metrology concepts, including lithography mask inspection, device metrology, and various applications in lithography research. ASML studies Soft x-ray (SXR) scatterometry using 10-20 nm wavelength light as a promising next-generation metrology technique for 3D profile metrology and overlay (OVL) applications. This wavelength regime offers unique benefits: (1) Short wavelengths allow for high-resolution measurements at device pitches; (2) Primarily single scattering yields low correlation between parameters and aids physical interpretation of signals; (3) SXR provides 3D capability, with stack heights up to 400 nm supported and high depth resolution due to the broadband source and sensor. We experimentally demonstrated feasibility of SXR scatterometry for various important metrology use cases. Further development of SXR into a mature metrology platform relies on improvements in XUV source technology. We will outline the corresponding research directions ASML is exploring for further XUV source development.