A desktop extreme ultraviolet microscope based on a compact laser-plasma light source

Abstract

research, such as mask inspection [6,7]-reaching 22-nm half pitch resolution or lithography [8], as well as free electron lasers [9] for coherent diffraction imaging (CDI) schemes [10]. These facilities, although state of the art and dedicated to cutting-edge science experiments, are not "user friendly," with limited user access and require high maintenance costs, because of their scale and complexity. Another approach is to use tabletop high-order harmonic (HHG) sources [11] for sub-100-nm spatial resolution imaging [12]; however, typical 10 −6 -10 −5 HHG conversion efficiency is very low and often does not allow for a proper reconstruction [13], the system is very complicated, and typical CDI requires time-consuming numerical data processing. Ptychographic schemes, although providing very high spatial resolution, are serial in nature, extensively time-consuming and computationally demanding.To partially overcome these limitations, other compact EUV sources, such as discharge [14], Z-pinch [15] or laserproduced plasma sources [16], coupled to zone plates or Schwarzschild mirrors, were used. The first one is compact and shows very good spatial resolution, but requires often (~30 k pulses) capillary replacements, the second one demonstrates quite low performance in terms of spatial resolution and field of view exploiting inadequate mode of imaging for lithographic mask inspection, while the last one requires debris mitigation schemes.The use of compact, short-wavelength sources often does not allow for high signal-to-noise ratio image acquisition. An example of that are recent developments in soft X-ray (SXR) microscopy in so-called water window, such as a compact soft X-ray microscope based on a single nitrogen gas jet, capable of resolving features ~100 nm later improved to ~50 nm in size providing high spatial resolution; however, the exposure time for Siemens star test pattern was equal to 1-2 h, limiting the usability of Abstract A compact, desktop size microscope, based on laser-plasma source and equipped with reflective condenser and diffractive Fresnel zone plate objective, operating in the extreme ultraviolet (EUV) region at the wavelength of 13.8 nm, was developed. The microscope is capable of capturing magnified images of objects with 95-nm full-pitch spatial resolution (48 nm 25-75% KE) and exposure time as low as a few seconds, combining reasonable acquisition conditions with stand-alone desktop footprint. Such EUV microscope can be regarded as a complementary imaging tool to already existing, well-established ones. Details about the microscope, characterization, resolution estimation and real sample images are presented and discussed.

Nanoimaging Using Soft X-Ray and EUV Sources Based on Double Stream Gas Puff Targets

“…A geometrical magnification of the objective was 410×. Such system, in this configuration, achieves a half-pitch spatial resolution of 48 nm [21]. More details about this system can be found in [22].…”

Nanoimaging using soft X-ray and EUV laser-plasma sources

“…The geometrical magnification of the objective was 410x, however, it can be easily changed by adjusting the FZP-CCD distance. Such system, in this configuration, is capable to achieve a half-pitch spatial resolution of 48 nm [26]. More details about this system can be found in [27].…”

Bioimaging Using Full Field and Contact EUV and SXR Microscopes with Nanometer Spatial Resolution

“…The geometrical magnification of the objective was 410×, however, it can be easily changed by adjusting the FZP-CCD distance. Such a system, in this configuration, is capable to achieve a half-pitch spatial resolution of 48 nm [38]. More details about this system can be found in [39].…”