KEYWORDS: Scanning electron microscopy, 3D image processing, 3D metrology, Design rules, Critical dimension metrology, Monte Carlo methods, Metrology, Manufacturing
As the manufacturing process is more integrated, in the field of metrology, there is an increasing demand for method to monitor local dispersion of measurement value that can trace randomly generated week points in the chip. Since it is difficult to obtain local dispersion with an optical method where the relatively large spot compared to the size of the target structure, many attempts have been made to use other method such as scanning electron microscopy (SEM). It is clear that SEM is suitable for obtaining local dispersion thanks to its high resolution, but it is difficult to obtain thickness information because only contrast data is included in the image. From these demands, a method using gray level (GL) index of the SEM image to estimate the depth of the target pattern has been proposed. However, because it is an index that simply correlates the GL value to the depth without considering pattern geometry, it follows different trends depending on the design rule and dispersion of the critical dimension (CD) and depth. In order to overcome this inhomogeneity of the GL index, in this study, we propose 3D GL index considering the field of view (FOV) of secondary electron (SE) emission according to the 3D geometry of the pattern. We apply effective FOV derived from SE emission function estimated by Lambertian distribution and CD and depth of the pattern to conventional GL index. As a result of applying it to the polysilicon hole pattern and comparing it with the vertical-SEM depth measurement, unlike the existing index, 3D GL index shows a clear linear trend with high correlation R2 of 0.781 regardless of design rule and dimension variation. In that it can more accurately and robustly respond to process variation, the proposed 3D GL index can increase the utilization of the depth monitoring method using SEM image.
In this study, a large area optically transparent frequency selecive surface absorber (OTFA) for dual-band millimeter-wave/IR stealth was designed and fabricated. ITO coated PET films were processed by wet etching and laminating with OCA in commercial display production process, 40cm*40cm size OTFA was fabricated. It achieved absorptivity over 95% at 35 GHz and 94 GHz. Also, transmission more than 65% in visible band. ITO pattern at the surface shows average emissivity less than 25%. The study's results suggest that the proposed absorber has significant potential in stealth technology for its large-scale production possibilities, with multispectral stealth performance.
Indirect digital X-ray scintillator has been widely used in various medical radiographic and diagnostic applications. To get a clear detection image for precise diagnosis with minimizing the X-ray radiation exposure to the patients, high performance X-ray scintillator is required. The double layer scintillator with having diffuse reflection layer is growing interest composed of highly-scattering scintillator particles are on top of the scintillator. However, since few researches has been studied for the scintillator, the analytic model for expecting and analyzing the scintillator performance is required. Here, we propose the analytic model for expecting the energy efficiency of the granular X-ray double layer scintillator, which is well matched with Monte-Carlo simulation in accuracy of 98%. And furthermore, we suggest the design strategy for achieving high energy efficiency with the satisfaction of sufficient spatial resolution and the design parameters, such as particle size and the thickness of the each layer, are determined. Compared with the Monte Carlo calculation time, our analytical calculation took time only half second, which was 40,000 times faster. Our simple, efficient analytic model has an impact that expectation of energy efficiency in X-ray double layer scintillator can be fulfilled easily without losing accuracy. Furthermore, various cases of design parameters can be tested in advance with the model before manufacturing and designing the X-ray scintillator devices.
Powder-based flat panel X-ray scintillator screen has been widely used in many medical fields for diagnosis and measurement. For the proper application in medical field, high dose usage and high image quality are required.
In this study, double-layer scintillator design is suggested for improving total efficiency with using theoretical x-ray absorption model and Mie-scattering-based Monte-Carlo (LightTools) analysis. Optimized scintillator layer design would be proposed with respect to the medical fields’ sufficient resolution-functionality.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.