Multiple attenuation during data processing does not guarantee a multiple-free final section. Multiple identification plays an important role in seismic interpretation. A target-oriented method for predicting 3D multiples on stacked or migrated cubes in the time domain is presented. The method does not require detailed knowledge of the subsurface geological model or access to prestack data and is valid for both surface-related and interbed multiples. The computational procedure is based on kinematic properties of the data and uses Fermat's principle to define the multiples. Since no prestack data are required, the method can calculate 3D multiples even when only multi-2D survey data are available. The accuracy and possible use of the method are demonstrated on synthetic and real data examples.
With the growing adoption of EUV lithography in both Logic and DRAM, the stochastics associated with EUV lithography has highlighted the need for accurate line roughness metrology. One of the approaches suggested to reduce stochastic effects is to transition to MOR (Metal Oxide Resist) from the traditional CAR resists. The CDSEM is the primary workhorse used today to measure line roughness in an inline environment. However, it is known that roughness reported by CD-SEM is dependent on the image acquisition conditions and the metrology algorithm settings. On the other hand, SEM metrology for EUV now requires low landing energies to minimize resist damage and increase contrast on thin high NA EUV resists [3]. However, this combination of low-dose scanning and low landing energies significantly lowers the contrast of the SEM image leading to higher reported roughness values using traditional roughness metrology algorithms. To understand and reduce the dependence of roughness on SEM image noise, we acquired images with different imaging conditions on a post-etch wafer and thin-resist EUV wafers with different stacks. The focus of this study is to demonstrate a novel roughness metrology algorithm that reduces the sensitivity of image SNR to roughness compared to traditional metrology methods. In this paper, we provide comprehensive guidelines for measuring unbiased roughness on thin EUV resist wafers in terms of roughness metrology and scanning conditions. We hope this work can provide the basis for understanding the roughness transfer from litho to etch and better characterize EUV lithography.
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