Fabrication of focused two-dimensional grids (original) (raw)
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Development of a freestanding copper antiscatter grid using deep X-ray lithography
Microsystem Technologies, 2003
A prototype freestanding copper antiscatter grid with parallel lamellar walls has been fabricated using deep X-ray lithography and electroforming. The freestanding copper grid has square shaped lamellar walls that are 25 lm thick and 1 mm tall with a 550 lm period. For mammography applications, the lamellar walls have to be aligned to a point X-ray source of the X-ray system. To achieve this goal, we investigated a dynamic doubleexposure technique. Our progress in using stacked exposures and use of the photoresist SU-8, both to reduce fabrication cost, is also presented.
Medical physics, 2016
Radiation scattered from the breast in digital breast tomosynthesis (DBT) causes image degradation, including loss of contrast between cancerous and background tissue. Unlike in 2-dimensional (2D) mammography, an antiscatter grid cannot readily be used in DBT because changing alignment between the tube and detector during the scan would result in unacceptable loss of primary radiation. However, in the dual modality breast tomosynthesis (DMT) scanner, which combines DBT and molecular breast tomosynthesis, the tube and detector rotate around a common axis, thereby maintaining a fixed tube-detector alignment. This C-arm geometry raises the possibility of using a 2D (cellular) focused antiscatter grid. The purpose of this study is to assess change in image quality when using an antiscatter grid in the DBT portion of a DMT scan under conditions of fixed radiation dose. Two 2D focused prototype grids with 80 cm focal length were tested, one stack-laminated from copper (Cu) and one cast fr...
Enhancement of X-ray Image's Resolution by using fabricated Anti Backscattered Radiation Grids
— This study aims to develop a method for enhancing x-ray image's resolution in radiology department, some fabricated grids with significant capability in reducing backscattered radiation are used to assessment its effectiveness in improving radiographic image resolution. The fabricated anti backscattered grids are designed from different materials with different geometric shapes. Image resolution test tool is exposed to produce x-ray images at different exposure parameters (kVp, mAs). The results of resolution indexes (LP/mm) illustrated remarkable effect of anti backscattered grids in improvement of x-ray image resolution up to 32%, with the use of crossed iron steel grid. Therefore, the effectiveness of fabricated grids in enhancing image resolution is dependent on the grid's material and design, as well as the radiation exposure parameters.
Design, Characterization, and Packaging for MEMS and Microelectronics, 1999
New developments for X-ray nanomachining include pattern transfer onto non-planar surfaces coated with electrodeposited resists using synchrotron radiation X-rays through extremely high-resolution masks made by chemically assisted focused ion beam lithography.
X-ray lathe: An X-ray lithographic exposure tool for nonplanar objects
Journal of microelectromechanical systems, 1996
An X-ray lithography lathe has been developed that can pattern cylindrical, ellipsoidal, and other nonplanar objects. This lathe is capable of patterning on a micron scale a wide variety of shapes including shapes impossible to achieve with a conventional lathe. A cylindrical core covered with a suitable resist is rotated while being exposed with a collimated X-ray source through a mask. The mask absorbs X rays up to a particular radius from the center of the core and the resist beyond that radius is removed in a developer. Several cylindrical cores were coated with poly(methylmethacry1ate) (PMMA) 5 to 125 pm thick and patterned with x-rays down to a 250-pm horizontal scale (along the lathe axis). The exposure time for a cylindrical PMMA layer is-three-four times longer than a planar layer with the same thickness. The capabilities of this technology, lathe apparatus, dose calculations, and initial exposure results are described in this paper. [176]
Proceedings of The IEEE, 1993
The fundamentals of X-ray lithography are reviewed. Issues associated with resolution, wafer throughput, and process latitude are discussed. X-ray lithography is compared with other lithographic technologies; future advancements, such as X-ray projection lithography, are described. It is shown that the major barrier to the near-term success of X-ray lithography is the requirement for a defect-fvee one-to-one mask which satisfies the stringent image-placement needs of submicrometer patterning.
Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena, 2002
A process aimed at fabricating proximity x-ray lithography masks is presented. In this technique, the Ta absorber layer is deposited and patterned on the back side of the membrane and nonspin-coated electron sensitive layers were used in order to achieve high resolution patterning of this absorber. The advantages gained by this approach include a reduction of the membrane temperature during the plasma etching step of the absorber patterns without using any cooling gas. This temperature reduction results from the direct contact of the membrane with a cooling plate. This approach also allows increased protection of the absorber patterns from contamination during exposure of the mask. A third advantage is that the smooth surface of the mask exposed to the wafer in the x-ray lithography stepper may also make it possible to reduce the gap between wafer and mask, thus achieving increased resolution with the x-ray lithography process.