Topic
Moiré pattern
About: Moiré pattern is a research topic. Over the lifetime, 1917 publications have been published within this topic receiving 27176 citations. The topic is also known as: moiré fringes & moire pattern.
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TL;DR: In this article, a four-channel focusing and leveling scheme based on dual grating marks is proposed and demonstrated, and the relationship between the tilted amount of wafer, the vertical defocusing amount, and phase distributions of moire fringes is deduced.
Abstract: Focusing and leveling are two imperative processes to adjust the wafer onto the ideal focal plane of projection lithography tools. Based on moire fringes formed by particularly designed dual-grating marks, the four-channel focusing and leveling scheme is proposed and demonstrated. These relationships between the tilted amount of wafer, the vertical defocusing amount, and the phase distributions of moire fringes are deduced. A single-channel experimental setup is constructed to verify the performances of proposed method. Results indicate that the tilted amount and the vertical defocusing amount can be precisely detected with accuracy at 10(-4) rad and several nanometers level, respectively, and therefore meet the demand of the high-demanding focusing and leveling processes.
6 citations
TL;DR: The proposed formulation removes the phase errors that are due to non-sinusoidal functions in any phase measurement systems that use phase-shifting techniques by taking in to account other harmonics of the grating function.
6 citations
TL;DR: In this paper, a new approach to obtaining the state of strain through moire fringes is presented, which utilizes the strain-rosette concept commonly used in strain gage techniques.
Abstract: In this paper a new approach to obtaining the state of strain through moire fringes is presented. It utilizes the strain-rosette concept commonly used in strain gage techniques. The advantage of this method over the conventional method is also described.
6 citations
Patent•
05 Feb 1977
6 citations
TL;DR: In this article, a multichannel imaging position-sensitive detector has been developed and characterized, with the novel feature of simultaneous measurement of strain and tilt at a large array of points, using principles of diffraction to directly measure strain at the desired points.
Abstract: A multipoint diffraction strain and tilt sensor using a multichannel imaging position-sensitive detector has been developed and characterized, with the novel feature of simultaneous measurement of strain and tilt at a large array of points. Unlike conventional interferometry based systems, this new whole-field measurement system uses principles of diffraction to directly measure strain at the desired points. The system utilizes a moire interferometer for the generation of two coherent and symmetric beams, which illuminate a high-frequency diffraction grating, bonded on the surface of the sample under test. The core of the system is a charge coupled device camera fitted with an array of microlenses, which samples the diffracted beam into an array of beamlets. The camera with lens array, which is being used as array-type multichannel position-sensitive detectors, senses the shift of the individual microspots. The deviation is then processed and the normal and shear strains are calculated at that spot along ...
6 citations