Local Line Density Research Articles

Slope error correction on X-ray reflection gratings by a variation of the local line density.

The patterning of x-ray grating surfaces by electron-beam lithography offers large flexibility to realize complex optical functionalities. Here, we report on a proof-of-principle experiment to demonstrate the correction of slope errors of the substrates by modulating the local density of the grating lines. A surface error map of a test substrate was determined by optical metrology and served as the basis for an aligned exposure of a corrected grating pattern made by electron-beam lithography. The correction is done by a variation of the local line density in order to compensate for the local surface error. Measurements with synchrotron radiation and simulations in the soft X-ray range confirm that the effects of slope errors were strongly reduced over an extended wavelength range.

Post Si(C)N hillock nucleation and growth in IC copper lines controlled by diffusional creep

Post Si(C)N hillocks are characterized on Cu interconnects networks. Each network is compounded by standard damascene process electroplated Cu lines with given width and local line density. AFM results show that total volume per area of post Si(C)N hillocks both on narrow and large lines increases linearly with local Cu line density. Two trends of hillocks nucleation and growth are highlighted depending on line width. For line widths inferior to 4 μm, hillocks are located at the line edge. As line density increases, the number of hillocks remains constant but their mean volume proportionally increases. For wider lines, hillocks preferentially nucleate at the center of the line. The number of hillocks proportionally increases as line density increases, but hillock mean volume remains constant. Post Si(C)N hillocks density is found to be proportional to post CMP Cu grain surface boundary density before capping. It is proposed that hillocks growth could be controlled by Cu/Ta interface diffusion on narrowest lines and by grain boundary diffusion on wider ones.

Illustrative Parallel Coordinates

AbstractIllustrative parallel coordinates (IPC) is a suite of artistic rendering techniques for augmenting and improving parallel coordinate (PC) visualizations. IPC techniques can be used to convey a large amount of information about a multidimensional dataset in a small area of the screen through the following approaches: (a) edge‐bundling through splines; (b) visualization of “branched ” clusters to reveal the distribution of the data; (c) opacity‐based hints to show cluster density; (d) opacity and shading effects to illustrate local line density on the parallel axes; and (e) silhouettes, shadows and halos to help the eye distinguish between overlapping clusters. Thus, the primary goal of this work is to convey as much information as possible in a manner that is aesthetically pleasing and easy to understand for non‐experts.

Development of illusory-contour perception in infants.

We investigated whether infants from 8-22 weeks of age were sensitive to the illusory contour created by aligned line terminators. Previous reports of illusory-contour detection in infants under 4 months old could be due to infants' preference for the presence of terminators rather than their configuration. We generated preferential-looking stimuli containing sinusoidal lines whose oscillating, abutting terminators give a strong illusory contour in adult perception. Our experiments demonstrated a preference in infants 8 weeks old and above for an oscillating illusory contour compared with a stimulus containing equal terminator density and movement. Control experiments excluded local line density, or attention to alignment in general, as the basis for this result. In the youngest age group (8-10 weeks) stimulus velocity appears to be critical in determining the visibility of illusory contours, which is consistent with other data on motion processing at this age. We conclude that, by 2 months of age, the infant's visual system contains the nonlinear mechanisms necessary to extract an illusory contour from aligned terminators.

A nonlinear normalization method for handprinted kanji character recognition—line density equalization

A nonlinear normalization method, the “line density equalization”, is proposed, where a resampling is done so as to equate the product of a local line density and a (variable) sampling pitch. Consequently, the line density in the space is homogenized, the efficiency of utilization of the space is increased, and a stable normalization is obtained for partially irregular shape variations. The method was applied to handprinted Kanji character recognition, and its effectiveness has been demonstrated.

Production of Beams with High Line-Density by Azimuthal Combination of Bunches in a Synchrotron

Simultaneous acceleration of several beams in the same machine by several RF fields of slightly different frequencies was already considered a long time ago1,2). As they rotate at different frequencies, the bunches will periodically coincide in azimuth, thus producing beams of high local line density. Bunches rotating at different frequencies can be produced either outside the machine (e. g. in the injector) or even inside by appropriate modulation of the RF cavities. These techniques will be used in the p-p- project at CERN. A high line-density proton beam, necessary for antiproton production, is obtained in the CPS by azimuthal combination, either at the injection or at the ejection level. On the other hand, the antiproton bunches in the SPS must be azimuthally combined before storage in order to achieve the design luminosity. Computer simulation and RF manipulations of these procedures, as well as experimental results already obtained at the CPS, are presented.