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Gregory Denbeaux

Bio: Gregory Denbeaux is an academic researcher from State University of New York Polytechnic Institute. The author has contributed to research in topics: Extreme ultraviolet lithography & Extreme ultraviolet. The author has an hindex of 9, co-authored 47 publications receiving 377 citations. Previous affiliations of Gregory Denbeaux include University at Albany, SUNY & State University of New York System.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a diffractive Fresnel zone plate lens was used for short wavelength x-ray radiation microscopy at the Advanced Light Source Synchrotron in Berkeley, California.
Abstract: Short wavelength x-ray radiation microscopy is well suited for a number of material and life science studies. The x-ray microscope (XM1) at the Advanced Light Source Synchrotron in Berkeley, California uses two diffractive Fresnel zone plate lenses. The first is a large condenser lens, which collects soft x-ray radiation from a bending magnet, focuses it, and serves as a linear monochromator. The second is the objective zone plate lens, which magnifies the image of the specimen onto a high-efficiency charge coupled device detector. The objective lens determines the numerical aperture and ultimate resolution. New objective lens zone plates with a minimum linewidth of 25 nm and excellent linewidth control have been fabricated using Berkeley Lab’s 100 keV Nanowriter electron beam lithography tool, a calixarene high-resolution negative resist, and gold electroplating. Although the condenser zone plate is less critical to the resolution of the instrument, its efficiency determines the flux on the sample and ul...

129 citations

Journal ArticleDOI
TL;DR: In this article, the three-dimensional magnetic structure and reversal mechanism of patterned Co/Pt multilayers were imaged using complementary Lorentz transmission electron microscopy (LTEM) and magnetic transmission x-ray microscopy(M-TXM) (perpendicular magnetization).
Abstract: The three-dimensional magnetic structure and reversal mechanism of patterned Co/Pt multilayers, were imaged using complementary Lorentz transmission electron microscopy (LTEM) (in-plane component) and magnetic transmission x-ray microscopy (M-TXM) (perpendicular magnetization). The Co/Pt films with perpendicular anisotropy were patterned by ion irradiation through a stencil mask to produce in-plane magnetization in the irradiated regions. The boundaries of the patterns, defined by the transition from out-of-plane to in-plane magnetization, were found to be determined by the stencil mask, whilst the scale of the magnetic reversal by the physical microstructure. The nucleation fields were substantially reduced to 50 Oe for the in-plane regions and 1 kOe for the perpendicular regions, comparing to 4.5 kOe for the as-grown film. The perpendicular reversals were found to always originate at the pattern boundaries.

33 citations

Proceedings ArticleDOI
TL;DR: In this paper, the International EUV Initiative (IEUVI) and SEMATECH have begun a resist outgassing benchmarking experiment to compare different outgashing methodologies.
Abstract: Optics contamination is a concern for extreme ultraviolet (EUV) lithography. To protect EUV optics, all materials used in EUV vacuum exposure chambers must be screened prior to use. Photoresists are a concern since a freshly coated wafer will be introduced into the chamber approximately every minute in a high volume production tool. SEMATECH and the International EUV Initiative (IEUVI) have begun a resist outgassing benchmarking experiment to compare different outgassing methodologies. Samples of the same batch of resist were sent to eight researchers. The results show a large variation of four orders of magnitude in the amount of measured outgassing products. The next steps are to correlate outgassing measurements to witness plate experiments.

32 citations

Proceedings ArticleDOI
TL;DR: In this paper, an electron exposure chamber was built to probe the behavior of electrons within photoresists and ellipsometry was used to identify the dependence of electron penetration depth and number of reactions on dose and energy.
Abstract: EUV photons expose photoresists by complex interactions starting with photoionization that create primary electrons (~80 eV), followed by ionization steps that create secondary electrons (10-60 eV). Ultimately, these lower energy electrons interact with specific molecules in the resist that cause the chemical reactions which are responsible for changes in solubility. The mechanisms by which these electrons interact with resist components are key to optimizing the performance of EUV resists. An electron exposure chamber was built to probe the behavior of electrons within photoresists. Upon exposure and development of a photoresist to an electron gun, ellipsometry was used to identify the dependence of electron penetration depth and number of reactions on dose and energy. Additionally, our group has updated a robust software that uses first-principles based Monte Carlo model called “LESiS”, to track secondary electron production, penetration depth, and reaction mechanisms within materials-defined environments. LESiS was used to model the thickness loss experiments to validate its performance with respect to simulated electron penetration depths to inform future modeling work.

22 citations

Proceedings ArticleDOI
TL;DR: In this paper, X-ray reflectometry is used to measure the absorbance and film quantum yields (FQY) of EUV photoresist resistors, which leads to the determination of absorbance.
Abstract: Base titration methods are used to determine C-parameters for three industrial EUV photoresist platforms (EUV- 2D, MET-2D, XP5496) and twenty academic EUV photoresist platforms. X-ray reflectometry is used to measure the density of these resists, and leads to the determination of absorbance and film quantum yields (FQY). Ultrahigh levels of PAG show divergent mechanisms for production of photoacids beyond PAG concentrations of 0.35 moles/liter. The FQY of sulfonium PAGs level off, whereas resists prepared with iodonium PAG show FQYs that increase beyond PAG concentrations of 0.35 moles/liter, reaching record highs of 8-13 acids generated/EUV photons absorbed.

19 citations


Cited by
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Journal ArticleDOI
30 Jun 2005-Nature
TL;DR: The achievement of sub-15-nm spatial resolution with a soft X-ray microscope—and a clear path to below 10 nm—using an overlay technique for zone plate fabrication is reported.
Abstract: The study of nanostructures is creating a need for microscopes that can see beyond the limits of conventional visible light and ultraviolet microscopes. X-ray imaging is a promising option. A new microscope described this week achieves unprecedented resolution, and has the ability to see through containing material. It features a specially made two-component zone plate — a lens with concentric zones rather like the rings in the Fresnel lenses familiar in overhead projectors and elsewhere — that makes use of diffraction to project an image into a CCD camera sensitive to soft X-rays. Spatial resolution of better than 15 nm is possible. Analytical tools that have spatial resolution at the nanometre scale are indispensable for the life and physical sciences. It is desirable that these tools also permit elemental and chemical identification on a scale of 10 nm or less, with large penetration depths. A variety of techniques1,2,3,4,5,6,7 in X-ray imaging are currently being developed that may provide these combined capabilities. Here we report the achievement of sub-15-nm spatial resolution with a soft X-ray microscope—and a clear path to below 10 nm—using an overlay technique for zone plate fabrication. The microscope covers a spectral range from a photon energy of 250 eV (∼5 nm wavelength) to 1.8 keV (∼0.7 nm), so that primary K and L atomic resonances of elements such as C, N, O, Al, Ti, Fe, Co and Ni can be probed. This X-ray microscopy technique is therefore suitable for a wide range of studies: biological imaging in the water window8,9; studies of wet environmental samples10,11; studies of magnetic nanostructures with both elemental and spin-orbit sensitivity12,13,14; studies that require viewing through thin windows, coatings or substrates (such as buried electronic devices in a silicon chip15); and three-dimensional imaging of cryogenically fixed biological cells9,16.

842 citations

Journal ArticleDOI
Bruce D. Terris1, T. Thomson1
TL;DR: Nanofabrication of magnetic storage media, where servo marks, discrete tracks or individual islands are defined, offers the prospect for improved performance and increased areal density as discussed by the authors.
Abstract: Nanofabrication of magnetic storage media, where servo marks, discrete tracks or individual islands are defined, offer the prospect for improved performance and increased areal density. However, this increase in performance will require that new and additional processes be introduced into disk manufacturing. We review here the fundamental patterning and fabrication processes that have been proposed, along with their respective strengths and weaknesses and the potential advantages they may offer for magnetic recording. The increase in data density afforded by nanofabrication may have added significance as more conventional approaches to ever increasing density will encounter physical limitations set by the thermal stability of the recorded bits.

824 citations

Journal ArticleDOI
TL;DR: Two new soft X-ray scanning transmission microscopes located at the Advanced Light Source (ALS) have been designed, built and commissioned and interferometer control implemented in both microscopes allows the precise measurement of the transverse position of the zone plate relative to the sample.
Abstract: Two new soft X-ray scanning transmission microscopes located at the Advanced Light Source (ALS) have been designed, built and commissioned. Interferometer control implemented in both microscopes allows the precise measurement of the transverse position of the zone plate relative to the sample. Long-term positional stability and compensation for transverse displacement during translations of the zone plate have been achieved. The interferometer also provides low-distortion orthogonal x, y imaging. Two different control systems have been developed: a digital control system using standard VXI components at beamline 7.0, and a custom feedback system based on PC AT boards at beamline 5.3.2. Both microscopes are diffraction limited with the resolution set by the quality of the zone plates. Periodic features with 30 nm half period can be resolved with a zone plate that has a 40 nm outermost zone width. One microscope is operating at an undulator beamline (7.0), while the other is operating at a novel dedicated bending-magnet beamline (5.3.2), which is designed specifically to illuminate the microscope. The undulator beamline provides count rates of the order of tens of MHz at high-energy resolution with photon energies of up to about 1000 eV. Although the brightness of a bending-magnet source is about four orders of magnitude smaller than that of an undulator source, photon statistics limited operation with intensities in excess of 3 MHz has been achieved at high energy resolution and high spatial resolution. The design and performance of these microscopes are described.

636 citations

Journal ArticleDOI
TL;DR: In this article, a review of ion-induced modifications of magnetic anisotropies and exchange coupling is presented, which is limited to radiation-induced structural changes giving rise to a modification of magnetic parameters.
Abstract: Owing to their reduced dimensions, the magnetic properties of ultrathin magnetic films and multilayers, e.g. magnetic anisotropies and exchange coupling, often depend strongly on the surface and interface structure. In addition, chemical composition, crystallinity, grain sizes and their distribution govern the magnetic behaviour. All these structural properties can be modified by light-ion irradiation in an energy range of 5–150 keV due to the energy loss of the ions in the solid along their trajectory. Consequently the magnetic properties can be tailored by ion irradiation. Similar effects can also be observed using Ga+ ion irradiation, which is the common ion source in focused ion beam lithography.Examples of ion-induced modifications of magnetic anisotropies and exchange coupling are presented. This review is limited to radiation-induced structural changes giving rise to a modification of magnetic parameters. Ion implantation is discussed only in special cases.Due to the local nature of the interaction, magnetic patterning without affecting the surface topography becomes feasible, which may be of interest in applications. The main patterning technique is homogeneous ion irradiation through masks. Focused ion beam and ion projection lithography are usually only relevant for larger ion masses. The creation of magnetic feature sizes below 50 nm is shown. In contrast to topographic nanostructures the surrounding area of these nanostructures can be left ferromagnetic, leading to new phenomena at their mutual interface.Most of the material systems discussed here are important for technological applications. The main areas are magnetic data storage applications, such as hard magnetic media with a large perpendicular magnetic anisotropy or patterned media with an improved signal to noise ratio and magnetic sensor elements. It will be shown that light-ion irradiation has many advantages in the design of new material properties and in the fabrication technology of actual devices.

284 citations

Journal ArticleDOI
TL;DR: Testing of the zone plate with the full-field transmission x-ray microscope, XM-1, in Berkeley, showed that the lens clearly resolved 12 nm lines and spaces, a significant step towards 10 nm resolution and beyond.
Abstract: To extend soft x-ray microscopy to a resolution of order 10 nm or better, we developed a new nanofabrication process for Fresnel zone plate lenses. The new process, based on the double patterning technique, has enabled us to fabricate high quality gold zone plates with 12 nm outer zones. Testing of the zone plate with the full-field transmission x-ray microscope, XM-1, in Berkeley, showed that the lens clearly resolved 12 nm lines and spaces. This result represents a significant step towards 10 nm resolution and beyond.

273 citations