Influence of base and photoacid generator on deprotection blur in extreme ultraviolet photoresists and some thoughts on shot noise

A contact-hole deprotection blur metric has been used to monitor the deprotection blur of an experimental open platform resist (EH27) as the wt % of base and photoacid generator (PAG) were varied. A six times increase in base wt % is shown to reduce the size of successfully patterned 1:1 line-space features from 52 to 39 nm without changing deprotection blur. Corresponding isolated line edge roughness is reduced from 6.9 to 4.1 nm. A two times increase in PAG wt % is shown to improve 1:1 line-space patterning from 47 to 40 nm without changing deprotection blur or isolated line edge roughness. A discussion of improved patterning performance as related to shot noise and deprotection blur concludes with a speculation that the spatial distribution of PAG molecules has been playing some role, perhaps a dominant one, in determining the uniformity of photogenerated acids in the resists that have been studied. © 2008 American Vacuum Society

Achieving diffraction-limited performance on the Berkeley MET5

The Berkeley MET5, funded by EUREKA, is a 0.5-NA EUV projection lithography tool located at the Advanced Light Source at Berkeley National Lab. Wavefront measurements of the MET5 optic have been performed using a custom in-situ lateral shearing interferometer suitable for high-NA interferometry. In this paper, we report on the most recent characterization of the MET5 optic demonstrating an RMS wavefront 0.31 nm, and discuss the specialized mask patterns, gratings, and illumination geometries that were employed to accommodate the many challenges associated with high-NA EUV interferometry

Poids des nouveau-nés et stratégies reproductrices des vipères européennes

The reproductive strategies of six species and two subspecies of European vipers are compared. Eighty eight clutches were examined. The reproductive effort, defined as the ratio of total litter weight over body weight of the female just after parturition, varies widely among individuals. This individual variation is in part due to the variable amount of fat accumulated by pregnant females during vitellogenesis, and therefore is associated with their nutrition during the gestation period. However, a genetic polymorphism cannot be ruled out in certain populations. The average reproductive effort of the varions species studied is 0.476 ; it does not significantly differ between the species concerned. Among the taxa studied, the average female body weight, just after parturition, ranges from 12.1 to 139.0 g, whereas that of the neonates ranges from 2.74 to 7.4 g, and their number from 2.0 to 8.9 per litter. Therefore the variation in neonatal body weight is smaller than that of the number of newborn per litter. Broadly speaking, small viper species bear fewer offsprings than larger ones, but these offspring are proportionately bigger. The distribution of the reproductive effort not only varies with the body size of the individual adult female ; it also depends on the species concerned, more particularly on the feeding habits and feeding opportunities of the newborn. Those which feed on invertebrates and, to a lesser extent, on small lizards, can afford to be small and numerous. This is not the case for the species whose young feed mostly on small mammals. Within a given taxon, the size of a litter generally increses with the body weight of the mother, whereas there is no correlation between the individual body weight of the newborn and that of their mother. The mortality rate of the young vipers during their first ten months of life varies greatly within the species concerned, at least in captivity. However, within a given species, the larger the newborn, the lower the mortality rate. In conclusion, the individual body weight of the newborn, and the variability of the reproductive effort among the various species of European vipers studied, depend on a number of different factors : female body size, feeding habits of the newborn, availability of prey, and mortality rates of the young in the postnatal period. The values observed under natural conditions obviously result from a compromise between different and often conflicting selective pressure

Overview and status of the 0.5NA EUV microfield exposure tool at Berkeley Lab

A 0.5-NA extreme ultraviolet micro-field exposure tool has been installed and commissioned at beamline 12.0.1.4 of the Advanced Light Source synchrotron facility at Lawrence Berkeley National Laboratory. Commissioning has demonstrated a patterning resolution of 13 nm half-pitch with annular 0.35-0.55 illumination; a patterning resolution of 8 nm half-pitch with annular 0.1-0.2 illumination; critical dimension (CD) uniformity of 0.7 nm 1σ on 16 nm nominal CD across 80% of the 200 um x 30 um aberration corrected field of view; aerial image vibration relative to the wafer of 0.75 nn RMS and focus control and focus stepping better than 15 nm

Carbon contamination topography analysis of EUV masks

The impact of carbon contamination on extreme ultraviolet (EUV) masks is significant due to throughput loss and potential effects on imaging performance. Current carbon contamination research primarily focuses on the lifetime of the multilayer surfaces, determined by reflectivity loss and reduced throughput in EUV exposure tools. However, contamination on patterned EUV masks can cause additional effects on absorbing features and the printed images, as well as impacting the efficiency of cleaning process. In this work, several different techniques were used to determine possible contamination topography. Lithographic simulations were also performed and the results compared with the experimental data

First lithographic results from the extreme ultraviolet Engineering Test Stand

The extreme ultraviolet ͑EUV͒ Engineering Test Stand ͑ETS͒ is a step-and-scan lithography tool that operates at a wavelength of 13.4 nm. It has been developed to demonstrate full-field EUV imaging and acquire system learning for equipment manufacturers to develop commercial tools. The initial integration of the tool is being carried out using a developmental set of projection optics, while a second, higher-quality, projection optics is being assembled and characterized in a parallel effort. We present here the first lithographic results from the ETS, which include both static and scanned resist images of 100 nm dense and isolated features throughout the ring field of the projection optics. Accurate lithographic models have been developed and compared with the experimental results

Première observations sur le comportement de chasse et de capture chez les vipères et les couleuvres

Chez Vipera, toute proie (vivante ou morte) agitée devant le Serpent est observée et suivie à vue ; ce n’est que très près que les sens chimiques entrent en jeu grâce aux mouvements de langue. C’est de ces derniers sens que dépend l’acceptation ou le refus définitif de la proie. La signification des proies chez les Vipères ne dépend que de leur motivation interne. Les proies ne laissent de pistes odorantes que par contact avec le sol ou différents objets naturels (pierres, souches, végétation, etc...). Lorsque les traces laissées par les proies s’entrecroisent, les Vipères ne peuvent pas discerner le sens des pistes odorantes et elles ne retrouvent leurs proies qu’après de nombreux essais et erreurs. La vue intervient d’abord dans la poursuite des proies vivantes non encore mordues et joue le rôle principal ; après morsure, le rôle des sens chimiques devient prédominant. La poursuite à l’aide de la langue semble liée à l’état de la proie. Une proie morte (envenimée ou non) peut être uniquement suivie à l’aide de la langue par sa trace, tandis qu’une proie vivante (bien que plus attractive) ne peut être suivie par sa trace qu’après morsure. Chez les Vipères, deux phénomènes bien distincts entrent en jeu avant la déglutition : 1° une reconnaissance olfactive, gustative et tactile à l’aide de la langue dont dépend l’acceptation définitive de la proie, et 2° une reconnaissance visuelle de la tête de la proie, point de départ de la déglutition. Dans les conditions naturelles, c’est-à-dire lorsque les proies sont vivantes, le comportement de chasse des Vipères dépend de deux phénomènes bien distincts : 1° avant la morsure, une poursuite où les mouvements de langue sont rares ou nuis et dans laquelle la vue joue le plus grand rôle. Cette poursuite est rapide et la tête de la Vipère, portée haute au-dessus du sol, reste toujours très près de la proie. Les deux parcours, celui de la Souris et de la Vipère sont plus ou moins superposables. Il faut rappeler que la Vipère voit mieux les mouvements de la proie que la proie elle-même ; 2° après une première morsure le rôle de la langue devient prépondérant. La poursuite est lente et s’effectue avec de nombreux mouvements intermittents de la langue. Le trajet parcouru par la Vipère est toujours sinueux, mais s’écarte peu de part et d’autre de la trace laissée par la Souris. Chez Natrix natrix et Natrix viperinus la prédation peut être divisée en deux parties : 1° un comportement de chasse sur le sol où la vue joue le plus grand rôle, sinon l’unique, et 2° un comportement de chasse dans l’eau où la vue et la langue interviennent simultanément. Un leurre en caoutchouc mousse figurant une Rainette (Hyla arborea) agité sur l’eau devant Natrix viperinus détermine le même comportement qu’une proie naturelle chez cette Couleuvre.Naulleau G. Première observations sur le comportement de chasse et de capture chez les vipères et les couleuvres. In: La Terre et La Vie, Revue d'Histoire naturelle, tome 18, n°1, 1964. pp. 54-76

CYCLE D'ACTIVITE DE VIPERA ASPIS (L.)ET CHOIXENTRE DES CONDITIONS CLIMATIQUESNATURELLES ET ARTIFICIELLES

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