We have developed an organic-inorganic hybrid resist platform featuring versatile ex-situ control of its performance by incorporating inorganic elements using vapor-phase infiltration (VPI) into standard organic resists. With poly(methyl methacrylate) (PMMA)-AlOx hybrid as a model composition we unveiled controllability of the critical exposure dose, contrast (as high as ~30), and etch resistance; estimated Si etch selectivity over ~300, demonstrating high aspect ratio ~17 with ~30 nm resolution Si fin-structures. Building upon the demonstration of PMMA-AlOx hybrid resist, we expanded our material portfolio to a high sensitivity resist and other inorganic moieties. We present preliminary results obtained from the extreme ultraviolet (EUV) lithography dose tests conducted on corresponding infiltrated hybrids and optimization of infiltration with the help of transmission electron microscopy (TEM).
We demonstrate a simple ex-situ inorganic infiltration route for transforming standard organic resists into high-performance positive tone hybrid resist platform. A model thin film PMMA-AlOx hybrid resist system has been synthesized by hybridization of PMMA with AlOx and investigated for electron beam lithography. The approach possesses full controllability of the resist performance in terms of critical does, patterning contrast reaching up to 30 and etch resistance for plasma-based pattern transfer processes. The high selectivity Si etching capability demonstrated using a low-temperature cryo-Si etch process, based on the controlled infiltration outperforms commercial resists and typical hard mask material thermal SiO2, with estimated achievable selectivity in excess of ~300. Si nanostructures down to ~30 nm with aspect ratio up to ~17 are also transferred into the Si substrate. Easy implementation and adaptability for different inorganic infiltrations, this platform is well capable of potentially delivering the resist performance and throughput necessary for EUV lithography.
Hard X-ray microscopy is a powerful scientific tool capable of providing sub-10 nm spatial resolution imaging of material’s chemical composition and internal structure. Multilayer Laue Lenses (MLLs) have been developed and used for hard x-ray nanofocusing. MLLs are one dimensional X-ray diffractive optics fabricated through multilayer deposition and sectioning. An orthogonal alignment of two MLLs yields a point focus; 10 milli-degree orthogonality and sub-10 µm positioning accuracy along the beam direction is required to avoid astigmatism and achieve 10 nm focal spot size at 12 keV photon energy. Up-to-date, developed x-ray microscopy systems were equipped with eight degrees of nano-scale motion to perform full alignment of individual MLL optics. Bonding of two individual lenses together in pre-determined configuration significantly simplifies alignment process and makes them compatible with a more conventional Zone Plate – based microscopes. In this work, we give an overview of the existing bonding effort and present our approach to fabricate a monolithic 2D MLL optic.
The external cavity tunable mid-infrared emitters based on Littrow configuration and utilizing three stages type-I quantum well cascade diode laser gain elements were designed and fabricated. The free-standing coated 7.5-μm-wide ridge waveguide lasers generated more than 30 mW of continuous wave power near 3.25 μm at 20°C when mounted epi-side-up on copper blocks. The external cavity lasers (ECLs) utilized 2-mm-long gain chips with straight ridge design and anti-/neutral-reflection coated facets. The ECLs demonstrated narrow spectrum tunable operation with several milliwatts of output power in spectral region from 3.05 to 3.25 μm corresponding to ∼25 meV of tuning range.
Proc. SPIE. 10132, Medical Imaging 2017: Physics of Medical Imaging
KEYWORDS: Semiconductors, Photon counting, Sensors, Signal attenuation, Electrodes, Luminescence, Crystals, X-rays, Monte Carlo methods, Detector development, X-ray imaging, Selenium, Signal detection, Prototyping, Breast imaging
Photon counting detectors (PCD) with energy discrimination capabilities have the potential for improved detector performance over conventional energy integrating detectors. Additionally, PCDs are capable of advanced imaging techniques such as material decomposition with a single exposure, which may have significant impact in breast imaging applications. Our goal is to develop a large area amorphous Selenium (a-Se) photon counting detector. By using our novel direct conversion field-Shaping multi-Well Avalanche Detector (SWAD) structure, the inherent limitations of low charge conversion gain and low carrier mobility of a-Se can be overcome. In this work we developed a spatio-temporal charge transport model to investigate the effects of charge sharing, energy loss and pulse pileup for SWAD. Using a monoenergetic 20 keV source we found that 32% of primary interactions have K-fluorescence emissions that escape the target pixel, 62.5% of which are reabsorbed in neighboring pixels, while 37.5% escape the detector entirely for a 100 μm × 100 μm pixel size. Simulated pulse height spectra for an input count rate of 50,000 counts/s/pixel with a 2 μs dead time was also generated, showing a photopeak FWHM = 2.6 keV with ~10% pulse pileup. Additionally we present the first time-of-flight (TOF) measurements from prototype SWAD samples, showing successful unipolar time differential (UTD) charge sensing. Our simulation and initial experimental results show that SWAD has potential towards making a large area a-Se based PCD for breast imaging applications.
Self-organizing block copolymer thin films hold promise as a photolithography enhancement material for the 22-nm microelectronics technology generation and beyond, primarily because of their ability to form highly uniform patterns at the relevant nm scale dimensions. Importantly, the materials are chemically similar to photoresist and can be implemented in synergy with photolithography. Beyond the challenges of achieving sufficient control of self-assembled pattern defects and feature roughness, block copolymer-based patterning requires creation of robust processes for transferring the polymer patterns into underlying electronic materials. Here, we describe research efforts in hardening block copolymer resist patterns using inorganic materials and high aspect ratio plasma etch transfer of self-assembled patterns to silicon using fluorine-based etch chemistries.
Self-organizing block copolymer thin films hold promise as a photolithography enhancement material for the 22-nm
microelectronics technology generation and beyond, primarily because of their ability to form highly uniform patterns at
the relevant nanometer-scale dimensions. Importantly, the materials are chemically similar to photoresists and can be
implemented in synergy with photolithography. Beyond the challenges of achieving sufficient control of self-assembled
pattern defectivity and feature roughness, block copolymer-based patterning requires creation of robust processes for
transferring the polymer patterns into underlying electronic materials. Here, we describe research efforts in hardening
block copolymer resist patterns using inorganic materials and high aspect ratio plasma etch transfer of self-assembled
patterns to silicon using fluorine-based etch chemistries.
Fresnel zone plates are important x-ray diffractive optics which offer a focusing resolution approaching the theoretical limit. In hard x-ray region, the refractive indices of all the materials are close to unity, which requests thick zone plate to achieve a reasonable efficiency. It makes high-resolution zone plate extremely difficult to fabricate due to its high aspect ratio. We report a LIGA-like fabrication process employing e-beam resist HSQ as the plating mold material, which is relative simply compared with traditional processes. 1-μm-thick gold zone plates with 80-nm-wide outermost zone have been fabricated with this process.