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Rader, Daniel J.

Publications and source records attributed to Rader, Daniel J..

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Methods and apparatus for use with extreme ultraviolet light having contamination protection

An apparatus for use with extreme ultraviolet (EUV) light comprising A) a duct having a first end opening, a second end opening and an intermediate opening intermediate the first end opening the second end opening, B) an optical component disposed to receive EUV light from the second end opening or to send light through the second end opening, and C) a source of low pressure gas at a first pressure to flow through the duct, the gas having a high transmission of EUV light, fluidly coupled to the intermediate opening. In addition to or rather than gas flow the apparatus may have A) a low pressure gas with a heat control unit thermally coupled to at least one of the duct and the optical component and/or B) a voltage device to generate voltage between a first portion and a second portion of the duet with a grounded insulative portion therebetween.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Particle control near reticle and optics using showerhead

A method and an apparatus to protect a reticle against particles and chemicals in an actinic EUV reticle inspection tool are presented. The method and apparatus utilizes a pair of porous metal diffusers in the form of showerheads to provide a continual flow of clean gas. The main showerhead bathes the reticle surface to be inspected in smoothly flowing, low pressure gas, isolating it from particles coming from surrounding volumes. The secondary showerhead faces away from the reticle and toward the EUV illumination and projection optics, supplying them with purge gas while at the same time creating a buffer zone that is kept free of any particle contamination originating from those optics.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Upscaling ab-initio chemistry models to non-equilibrium flow simulations

Thermochemical nonequilibrium is generated by hypersonic cruise vehicles, high speed combustion and detonations. Nonequilibrium interactions affect reaction rates and energy transfer that are critical for many engineering applications. Ab-initio potential energy surfaces can be used in quasi-classical trajectory (QCT) calculations to calculate state-specific dissociation rates and cross sections, as well as state-to-state energy exchange rates and cross sections. These rates and cross sections are needed for simulating such nonequilibrium flows. However, there are two main challenges in extending QCT calculations to modeling all chemical processes found in typical engineering flowfields. First, ab-initio surfaces for many collision partners are not available and when available their fidelity is not quantified. Second, state-to-state cross section datasets are typically on the order of 1000 4, , and are too large to be efficiently implemented in engineering simulations. This work focuses on O 2 +O interactions because of prevalence of oxygen in many engineering application; however, all of the models developed here may be applied to other diatom-atom interactions and can be extended to other diatom-diatom combinations. It is shown in this work that at temperatures between 2,500 and 20,000K, state-specific cross sections are not highly sensitive to potentials and a Morse additive pairwise (MAP) potential is proposed for modeling collisions for which ab-initio potentials are not available. Next, this work suggests an approach to model state-to-state cross sections based on maximum entropy considerations. The calculated cross sections are fit to a new model with just 8 parameters, which can be easily scaled up to flow simulations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Protection of extreme ultraviolet lithography masks. II. Showerhead flow mitigation of nanoscale particulate contamination [Protection of EUV lithography masks II: Showerhead flow mitigation of nanoscale particulate contamination]

An analysis is presented of a method to protect the reticle (mask) in an extreme ultraviolet (EUV) mask inspection tool using a showerhead plenum to provide a continuous flow of clean gas over the surface of a reticle. The reticle is suspended in an inverted fashion (face down) within a stage/holder that moves back and forth over the showerhead plenum as the reticle is inspected. It is essential that no particles of 10-nm diameter or larger be deposited on the reticle during inspection. Particles can originate from multiple sources in the system, and mask protection from each source is explicitly analyzed. The showerhead plate has an internal plenum with a solid conical wall isolating the aperture. The upper and lower surfaces of the plate are thin flat sheets of porous-metal material. These porous sheets form the top and bottom showerheads that supply the region between the showerhead plate and the reticle and the region between the conical aperture and the Optics Zone box with continuous flows of clean gas. The model studies show that the top showerhead provides robust reticle protection from particles of 10-nm diameter or larger originating from the Reticle Zone and from plenum surfaces contaminated by exposure to the Reticle Zone. Protection is achieved with negligible effect on EUV transmission. Furthermore, the bottom showerhead efficiently protects the reticle from nanoscale particles originating from the Optics Zone.

36 MATERIALS SCIENCE↗