[en] Soft X-ray microscopy provides element specific magnetic imaging with a spatial resolution down to 15nm. At XM-1, the full-field soft X-ray microscope at the Advanced Light Source in Berkeley, a stroboscopic pump and probe setup has been developed to study fast magnetization dynamics in ferromagnetic elements with a time resolution of 70ps which is set by the width of the X-ray pulses from the synchrotron. Results obtained with a 2 (micro)m x 4 (micro)m x 45nm rectangular permalloy sample exhibiting a seven domain Landau pattern reveal dynamics up to several nsec after the exciting magnetic field pulse. Domain wall motion, a gyrotropic vortex motion, and a coupling between vortices in the rectangular geometry are observed

[en] Full-field magnetic soft X-ray transmission microscopy is a powerful tool to study with elemental sensitivity at a lateral resolution down to 15nm micromagnetic structures and microscopic magnetization reversal phenomena in ferromagnetic systems such as thin films, magnetic multilayers, micropatterned elements and arrays. Fast spin dynamics in such systems can be addressed with a temporal resolution below 100ps by a stroboscopic pump-and-probe scheme. The current status of the imaging soft X-ray microscopy beamline XM-1 at the Advanced Light Source is reported. and future perspectives with respect to improved spatial and temporal resolution are described

[en] In e-beam lithography, fabrication of sub-20 nm dense structures is challenging. While there is a constant effort to develop higher resolution resist processes, the progress of increasing pattern density is slow. For zone plates, consisting of dense lines and spaces, the outermost zone width has been limited to slightly less than 20 nm due to effects such as low aerial image contrast, forward scattering, intrinsic resist resolution, and development issues. To circumvent these effects, we have successfully developed a new double patterning HSQ process, and as a result, we have fabricated zone plates of 10 and 12 nm using the process. We previously developed a double patterning process in which a dense zone plate pattern is sub-divided into two semi-isolated, complementary zone set patterns. These patterns are fabricated separately and then overlaid with high accuracy to yield the desired pattern. The key to success with this process is the accuracy of the overlay. For diffraction-limited zone plates, accuracy better than one-third of the smallest zone width is needed. In our previous work, the zone set patterns were formed using PMMA and gold electroplating, which were overlaid and aligned to the zero-level mark layer with sub-pixel accuracy using our internally developed algorithm. The complete zone plate fabrication was conducted in-house. With this process, we successfully fabricated zone plates of 15 nm outermost zone. Using this zone plate, we were able to achieve sub-15 nm resolution at 1.52 nm wavelength, the highest resolution ever demonstrated in optical microscopy at that time. We attempted to extend the process to fabricating 12 nm and smaller zones. However, the modest PMMA contrast, combined with a relatively large electron beam size compared to the target feature sized limited the process latitude. To overcome this problem, we developed a new overlay process based on high resolution negative tone resist of hydrogen silsesquioxane (HSQ). With the development in TMAH at 45 C, we can reliably achieve zone width as small as 8 nm with negligible line edge roughness in the semi-dense zone set. Such narrow zones in HSQ, however, detach easily from the gold plating base substrate needed for the electroplating step. We developed a process to condition the gold substrate with (3-mercaptopropyl) trimethoxysilane, or 3-MTP, which can form a homogeneous hydroxylation surface on gold surface and bond with hydroxyl in HSQ. Fig 2 shows the basic process steps of the double patterning HSQ process. Unlike the PMMA process, both zone sets are formed in HSQ and overlaid, and the complete zone plate pattern is converted to gold using electroplating in the final step. Using the new process, we successfully realized zone plates of 10 nm and 12 nm outermost zones. Fig. 3 shows the SEM micrographs of the zone plates outer regions. The zone plates are 30 nm thick in gold. To the best of our knowledge, these zone plates have the smallest zonal features ever fabricated using e-beam lithography. The complete zone plate fabrication was conducted in-house, using our vector scan electron beam lithography tool, the Nanowriter, which has a measured beam diameter of 6.5 nm (FWHM) at 100 keV. An internally developed, sub-pixel alignment algorithm, based on auto/cross-correlation methods, was used for the overlay. A 12 nm zone plate was tested with a full-field transmission x-ray microscope at the LBNL's Advanced Light Source. Fig. 4 shows an x-ray image of a 40 nm thick gold radial spoke pattern taken with the zone plate at 1.75 nm wavelength (707eV, FeL3 edge), along with the scanning transmission electron micrograph of same object. Numerous small features in the object can be seen in the x-ray image. Data analysis indicates that a near diffraction limited performance was achieved using the zone plate. In our presentation, we will discuss the details and subtleties of the overlay fabrication as well as the zone plate image results.

No abstract available

[en] The soft x-ray, full-field microscope XM-1 at Lawrence Berkeley National Laboratory's (LBNL) Advanced Light Source has already demonstrated its capability to resolve 25-nm features. This was accomplished using a micro zone plate (MZP) with an outer zone width of 25 nm. Limited by the aspect ratio of the resist used in the fabrication, the gold-plating thickness of that zone plate is around 40 nm. However, some applications, in particular, biological imaging, prefer improved efficiency, which can be achieved by high-aspect-ratio zone plates. We accomplish this by using a bilayer-resist process in the zone plate fabrication. As our first attempt, a 40-nm-outer-zone-width MZP with a nickel-plating thickness of 150 nm (aspect ratio of 4:1) was successfully fabricated. Relative to the 25-nm MZP, this zone plate is ten times more efficient. Using this high-efficiency MZP, a line test pattern with half period of 30 nm is resolved by the microscope at photon energy of 500 eV. Furthermore, with a new multilayer mirror, the XM-1 can now perform imaging up to 1.8 keV. An image of a line test pattern with half period of 40 nm has a measured modulation of 90%. The image was taken at 1.77 keV with the high-efficiency MZP with an outer zone width of 35 nm and a nickel-plating thickness of 180 nm (aspect ratio of 5:1). XM-1 provides a gateway to high-resolution imaging at high energy. To measure frequency response of the XM-1, a partially annealed gold ''island'' pattern was chosen as a test object. After comparison with the SEM image of the pattern, the microscope has the measured cutoff of 19 nm, close to the theoretical one of 17 nm. The normalized frequency response, which is the ratio of the power density of the soft x-ray image to that of the SEM image, is shown in this paper

[en] Soft x-ray zone plate microscopy provides a unique combination of capabilities that complement those of electron and scanning probe microscopies. Tremendous efforts are taken worldwide to achieve sub-10 nm resolution, which will permit extension of x-ray microscopy to a broader range of nanosciences and nanotechnologies. In this paper, the overlay nanofabrication technique is described, which permits zone width of 15 nm and below to be fabricated. The fabrication results of 12 nm zone plates, and the stacking of identical zone patterns for higher aspect ratio, are discussed

[en] Typically the performance of Photoemission Electron Microscopes (PEEM) is reported as one number, representative of a microscope's ultimate performance under an ideal set of conditions. Often a simple Rayleigh criterion is used which defines the spatial resolution approximately as the minimum distance of two still distinguishable features. However, the ability of an instrument to provide meaningful spectroscopic and microscopic information depends on the contrast loss of a pattern over a much wider range of spatial frequencies. For example, the chemical signature of one area on the sample can be contaminated from an adjacent area although both areas are still easily distinguishable in a microscopic image. We report here on a more comprehensive measurement of the PEEM-II instrument at beamline 7.3.1.1 at the Advanced Light Source (ALS) that examines the response of the instrument to a wide range of experimental conditions