Nebulous hotspot and algorithm variability in computation lithography

Computation lithography relies on algorithms. However, these algorithms exhibit variability that can be as much as 5% (one standard deviation) of the critical dimension for the 65-nm technology. Using hotspot analysis and fixing as an example, we argue that such variability can be addressed on the algorithm level via controlling and eliminating its root causes, and on the application level by setting specifications that are commensurate with both the limitations of the algorithms and the goals of the application. © 2010 Society of Photo-Optical Instrumentation Engineers.published_or_final_versio

Regularization of inverse photomask synthesis to enhance manufacturability

Mask manufacturability has been considered as a major issue in the adoption of inverse lithography (IL) in practice. With smaller technology nodes, IL distorts the mask pattern more aggressively. The distorted mask often contains curvilinear contour and irregular shapes, which cast a heavy computation burden on segmentation and data preparation. Total variation (TV) has been used for regularization in previous work, but it is not very effective in regulating the mask shape to be rectangular. In this paper, we apply TV regularization not only on the mask image but also on the mask edges, which forces the curves of edges to be more vertical or horizontal, because they give smaller TV values. Except for rectilinearity, a group of geometrical specifications of the mask pattern set by mask manufacture rule control (MRC) is also important for mask manufacturability. To prevent these characteristics from appearing, we also propose an intervention scheme into the optimization framework. © 2009 Copyright SPIE - The International Society for Optical Engineering.published_or_final_versionThe SPIE Lithography Asia 2009, Taipei, Taiwan, 18 November 2009. in Proceedings of SPIE, 2009, v. 7520, p. 1-11, article no. 75200

Alternating phase-shifting mask design for low aberration sensitivity

Theories are developed to optimize the mask structure of alternating phase-shifting masks (PSMs) to minimize the average image placement error towards aberration under coherent imaging. The constraint of the optimization is a given mean value of RMS aberration, which corresponds to infinitely many sets of random Zernike coefficients. To begin the analysis, the image placement error is expressed as a function of the mask spectrum and the wave aberration. Monte Carlo analysis on the Zernike coefficients is then performed, which assures us that a global minimum of average image placement error is likely to occur at low phase widths. This result is confirmed by analytically considering the expected value of the square of the image placement error. By Golden Section Search, the optimal phase width is found to be 0.3707(λ/NA) at 0.07λ RMS aberration. This methodology of finding the optimal phase width is applicable to the design of all alternating PSMs.published_or_final_versio

Standard cell layout with regular contact placement

The practicability and methodology of applying regularly placed contacts on layout design of standard cells are studied. The regular placement enables more effective use of resolution enhancement technologies, which in turn allows for a reduction of critical dimensions. Although placing contacts on a grid adds restrictions during cell layout, overall circuit area can be made smaller by a careful selection of the grid pitch, allowing slight contact offset, applying double exposure, and shrinking the minimum size and pitch. The contact level of 250 nm standard cells was shrunk by 10%, resulting in an area change ranging from -20% to +25% with an average decrease of 5% for the 84 cells studied. The areas of two circuits, a finite-impulse-response (FIR) filter and an add-compare-select (ACS) unit in the Viterbi decoder, decrease by 4% and 2%, respectively.published_or_final_versio

Performance optimization for gridded-layout standard cells

The grid placement of contacts and gates enables more effective use of resolution enhancement techniques, which in turn allow a reduction of critical dimensions. Although the regular placement adds restrictions during cell layout, the overall circuit area can be made smaller and the extra manufacturing cost can be kept to the lowest by a careful selection of the grid pitch, using template-trim lithography method, allowing random contact placement in the vertical direction, and using rectangular rather than square contacts. The purpose of this work is to optimize the gridded-layout-based process. The trade-off between the layout area and manufacturing cost, and the determination of the minimum grid pitch are discussed in this paper. We demonstrate that it is a 1-D scaling instead of the conventional 2-D scaling for standard cells and the narrow MOSFETs inside after the application of the gridded layout on the contact and gate levels. The corresponding effects on circuit performances, including the leakage current, are also explored.published_or_final_versio

Standard cell design with resolution-enhancement-technique-driven regularly placed contacts and gates

The practicability and methodology of applying resolution-enhancement- technique-driven regularly placed contacts and gates on standard cell layout design are studied. The regular placement enables more effective use of resolution enhancement techniques (RETs), which in turn enables a reduction of critical dimensions. Although regular placement of contacts and gates adds restrictions during cell layout, the over-all circuit area can be made smaller and the number of extra masks and exposures can be kept to the lowest by careful selection of the grid pitch, using template-trim chromeless phase-shifting lithography approaches, enabling unrestricted contact placement in one direction, and using rectangular rather than square contacts. Four different fabrication-friendly layouts are compared. The average area change of 64 standard cells in a 130-nm library range from -4.2 to -15.8% with the four fabricationfriendly layout approaches. The area change of five test circuits using the four approaches range from -16.2 to +2.6%. Dynamic power consumption and intrinsic delay also improve with the decrease in circuits area, which is verified with the examination results. © 2005 Society of Pnoto-Optical Instrumentation Engineers.published_or_final_versio

E-Macsc: A Novel Dynamic Cache Tuning Technique to Maintain the hit ratio prescribes by the user in internet applications

Department of ComputingRefereed conference pape

Prioritization of responsive maintenance tasks via machine learning-based inference

Maintenance task prioritization is essential for allocating resources. It is estimated that almost 1/3 of the maintenance cost is wasted to unnecessary activities. Task prioritization is based on risk assessment that takes into account the probability of failure and the criticality of an asset. The criticality analysis is defined by the asset owner based on several parameters, among them safety, downtime cost, productivity, whilst the probability of failure is determined based on deterioration models, regular manual inspections, or installed sensors. Currently, the latter is an extremely complicated and labour intensive procedure, when multiple and different types of assets need to be managed. This paper proposes an innovative method that exploits the advances in mobile communications, social networking, Internet of Things and machine learning to address this shortcoming. This approach brings building elements and assets online using asset tags with an online ‘asset profile’ linked to it. Users of assets are able to scan these tags using a mobile phone app to not only see the information about those assets, but also enter ‘comments’ describing issues and problems on the profiles. These comments are processed through machine learning-based inference methods to estimate the probability that a failure has occurred. This paper validates the proposed method using historical data collected from the Estate Management, of the University of CambridgeInnovate U

Diagnosis of acute surgical abdomen – The best diagnostic tool to reach a final diagnosiscin

AbstractObjectiveTo evaluate the best diagnostic tool (clinical, radiological, laboratory, or endoscopy) used to reach a final diagnosis of four most common presentations of acute abdomen to the surgical unit in the Limerick University Hospital, Limerick, Ireland.MethodsData was analyzed retrospectively of prospective collected data of all patients who had been admitted at a single academic institution from July 2011 till September 2011. Radiology, operating theatre and histopathology, haematology and endoscopy databases were searched from the Hospital Inpatient Enquiry (HIPE) department for patients who had presented with acute abdominal pain. Patients' charts were searched manually and final diagnosis of each patient was recorded.ResultsOut of 30 confirmed final diagnosis of appendicitis or appendicular mass, 9/30 (30.0%) were diagnosed with radiological (either on ultrasonography or CT scan). The remaining 21 cases (70.0%) were diagnosed clinically. Majority cases of diverticulitis 16/22 (72.7%) was diagnosed radiologically compared to only 6/22 (27.3%) of those confirmed by endoscopy. All diagnosis of gallstone-related diseases (cholecytitis, biliary colic, or cholelithiasis and/or choledocholithiasis) and bowel obstruction were confirmed by radiological investigation.ConclusionsAppendicitis can be accurately diagnosed clinically based on history and clinical examination alone. Diagnosis of diverticular disease, gallstone disease, and bowel obstruction further requires radiology intervention to confirm the provisional diagnosis

Attitudes towards advertising in dentistry in Hong Kong

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