Actinic defect counting statistics over 1-cm2 area of EUVL mask blank
As a continuation of comparison experiments between EUV inspection and visible inspection of defects on EUVL mask blanks, we report on the result of an experiment where the EUV defect inspection tool is used to perform at-wavelength defect counting over 1 cm2 of EUVL mask blank. Initial EUV inspection found five defects over the scanned area and the subsequent optical scattering inspection was able to detect all of the five defects. Therefore, if there are any defects that are only detectable by EUV inspection, the density is lower than the order of unity per cm2. An upgrade path to substantially increase the overall throughput of the EUV inspection system is also identified in the manuscript.
Cross-correlation between actinic and visible defect inspection tool for extreme ultraviolet lithography
We present recent experimental results from an actinic (operates at the EUV wavelength) defect inspection system for extreme ultraviolet lithography mask blanks. A method to cross-register and cross-correlate between the actinic inspection system and a commercial visible-light scattering defect inspection system is demonstrated. Thus, random, real defects detected using the visible-light scattering inspection tool can be found and studied by our actinic inspection tool. Several defects with sub-100 nm size (as classified by the visible scattering tool) are found with the actinic inspection tool with a good signal to noise ratio. This result demonstrates the capability of the actinic inspection tool for independent defect counting experiments at a sub-100 nm defect sensitivity level.
Arc flash hazard assessment in the mining industry
When it comes to electrical safety in the workplace, arc flash has become the most prominent topic over the past decade. The Occupational Safety and Health Administration (OSHA, including state chapters) is the only government body that recognizes NFPA-70E, Standard for Electrical Safety in the Workplace. However, OSHA does not have jurisdiction in mining operations. Electrical safety for the metal and nonmetal surface mining industry is covered by the Code of Federal Regulations (CFR) Title 30, Part 56, Subpart K (Electricity). The Mine Safety and Health Administration (MSHA) is responsible for enforcing electrical safety in mining operations. CFR Title 30 does not reference personal protective equipment (PPE) to protect electrical workers against arc flash hazards. This paper provides maintenance and safety personnel in surface Metal/Nonmetal mining operations with a step by step guide to implementing an electrical safety program that meets the requirements of MSHA, CFR Title 30 and NFPA-70E.