Measurements of the Trigger Rate of Drift Velocity Chambers

Today’s particle physics is interested in exploring the origin and the components of matter and its basic interactions. There are plenty of physical theories that intend to describe these phenomena, e.g. the Standard Model (SM), the Higgs mechanism or the Minimal Supersymmetric Standard Model (MSSM). However their correctness has to be proven with the help of experiments. So far the SM is the only theory that has been verified (more about the SM can be read in section 1.1 on page 4). There are two types of experiments with which physicists are able to investigate these theories: Either high energetic particles from the outer space are observed (AUGER1) or accelerated particles are brought to collision. The latter option is performed at CERN2 situated in Geneva, Switzerland

The voxel onset time as an in situ method to evaluate focal position effects on two-photon-induced lithography

Two-photon-induced lithography is a versatile method to generate arbitrary three-dimensional microstructures. Although the lithographic result sensitively depends on the experimental conditions, there is a lack of in situ methods to measure process conditions prior to structuring. Current methods rely on determining the size of cross-linked structures, such as single-volume pixels (voxels), as a result of a set of parameters. This procedure is time consuming and possesses several inherent drawbacks, since results are not easily interpretable. Therefore, we established an in situ method, called the voxel onset time (VOT) method, which is easy to integrate in an existing two-photon lithographic setup and is based on determining the time that a voxel necessitates to form by measuring the transmitted laser intensity. In this study, we demonstrate how the VOT method can be used to determine the influence of the axial focal position on voxel formation for different experimental conditions. We find that the voxel onset time is strongly linked to the maximum intensity that is influenced by specimen-induced spherical aberration, especially for a high-numerical-aperture objective

Achromatic Talbot lithography with partially coherent extreme ultraviolet radiation: process window analysis

The main purpose of this work is the experimental determination of the process window for achromatic Talbot lithography with partially coherent extreme ultraviolet (EUV) radiation. This work has been performed using the EUV laboratory exposure tool. It consists of a discharge produced plasma source with a direct beam path to a phase-shifting transmission mask, avoiding losses due to additional optical components, the photoresist-coated wafer, and a positioning system for each component. Both the source and the mask are optimized for 11-nm wavelength. The process window has been identified by a systematic analysis of several exposure series. The optimization of exposure parameters resulted in 50-nm half-pitch of the wafer features using a transmission mask with a rectangular dot array of 70-nm half-pitch. The depth of field is found to be 20  μm, and it can be extended by spatial filtering. The exposure dose and mask–wafer distance are varied around their optimal values to estimate the process window, using defectivity of the pattern as a control parameter

Enabling laboratory EUV research with a compact exposure tool

In this work we present the capabilities of the designed and realized extreme ultraviolet laboratory exposure tool (EUVLET) which has been developed at the RWTH-Aachen, Chair for the Technology of Optical Systems (TOS), in cooperation with the Fraunhofer Institute for Laser Technology (ILT) and Bruker ASC GmbH. Main purpose of this laboratory setup is the direct application in research facilities and companies with small batch production, where the fabrication of high resolution periodic arrays over large areas is required. The setup can also be utilized for resist characterization and evaluation of its pre- and post-exposure processing. The tool utilizes a partially coherent discharge produced plasma (DPP) source and minimizes the number of other critical components to a transmission grating, the photoresist coated wafer and the positioning system for wafer and grating and utilizes the Talbot lithography approach. To identify the limits of this approach first each component is analyzed and optimized separately and relations between these components are identified. The EUV source has been optimized to achieve the best values for spatial and temporal coherence. Phase-shifting and amplitude transmission gratings have been fabricated and exposed. Several commercially available electron beam resists and one EUV resist have been characterized by open frame exposures to determine their contrast under EUV radiation. Cold development procedure has been performed to further increase the resist contrast. By analyzing the exposure results it can be demonstrated that only a 1:1 copy of the mask structure can be fully resolved by the utilization of amplitude masks. The utilized phase-shift masks offer higher 1st order diffraction efficiency and allow a demagnification of the mask structure in the achromatic Talbot plane

Analysis of distinct scattering of extreme ultraviolet phase and amplitude multilayer defects with an actinic dark-field microscope

The authors report on experimental and simulative scattering analyses of phase and amplitude defects found in extreme ultraviolet multilayer mirrors, such as mask blanks for EUV lithography. The goal of the analyses is to develop a novel mask blank inspection procedure using one single inspection tool that allows to determine whether a defect is a surface type (amplitude) defect, or a buried type (phase) defect. The experiments were carried out with an actinic dark-field reflection microscope. Programmed defects of both types were fabricated, using different nanostructuring techniques. Analytical and rigorous scattering simulations were carried out to predict and support the experimental results