To evaluate tear production in the common mynah ( Acridotheres tristis ) using the phenol red thread test (PRTT) and to make a comparison of measurements with the PRTT placed in the fornices of lower and upper eyelids, tear production of both eyes in 22 healthy adult captive mynah birds was evaluated. After positioning of threads in the fornices of upper and lower eyelids, the PRTT values of the birds were 17.5 ± 3.1 mm/15 s and 19.2 ± 2.5 mm/15 s, respectively. A significant difference was found between PRTT values for upper eyelids and lower eyelids (P = 0.01). This study provides novel data for normal reference ranges of PRTT values in healthy common mynah birds and shows that a difference is found depending on where the PRTT thread is placed.

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Increasing demand in technology requirements from IC manufacturers has necessitated that photolithography equipment suppliers design and build tools with many advanced capabilities. These additional features not only add to the complexity of the tools, but also increase the cost. Therefore, in order to keep lithography affordable, it is essential that equipment suppliers increase equipment productivity and extend tool lifetimes to support multiple process generations.As a further challenge, the requirements from different IC manufacturers can be quite dissimilar even for the same technology node (as defined according to the ITRS roadmap). For example, for upcoming process nodes logic manufacturers may require enhanced flexibility to enable imaging of smaller and more complicated features, coupled with tighter overlay performance. In contrast, memory manufacturers may put more emphasis on Critical Dimension Uniformity (CDU) control. Therefore, today's photolithography scanners must be equipped with the latest technologies to achieve better resolution and heightened overlay accuracy, while at the same time delivering continuous improvements to throughput.In order to extend the usable lifetime of the scanner on to nextgeneration technologies, the system platform must also accommodate further improvements and/or upgrades to achieve the demanding requirements of the future. In addition, the scanners must be flexible enough to integrate Complementary Technologies (CT) that are being developed in parallel to further enhance scanner performance.Litho scanner suppliers are actively addressing these issues and Nikon has developed the Sx20 platform to provide an extendible platform for dry and immersion scanner applications. Immersion scanners such as the NSR-S620D are currently being used in mass production, and support future upgrades to enable enhancements to accuracy and throughput for next-generation manufacturing.In this paper some of the key design concepts of an extendible scanner platform will be discussed. These include enhancing the accuracy and maximizing productivity of the manufacturing environment, which is vital in ensuring the affordability of lithography in the future. To show industry progress in these areas, current performance from leading edge scanners that include overlay, auto focus, and Optical Proximity Effect (OPE) matching data will be presented. In addition, it will be shown how these scanners deliver overlay accuracy sufficient for the 32 nm node and beyond, with focus uniformity less than 20nm (3σ), while utilizing a platform capable of throughput up to 200 wafers per hour.Further, to support future technology nodes, scanners also need to accommodate advanced imaging solutions such as free form illumination sources, Source Mask Optimization (SMO) and Double Pattern Techniques (DPT). Some of these technologies, as well as how they must be integrated with flexible and extendible scanner platforms in order to keep next-generation lithography affordable, will be discussed in this paper [1].

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Immersion lithography has gone through its first phase of introduction and acceptance as the main solution for critical layer lithography for 45nm node and beyond. In this phase, the industry has found that immersion technology has its own unique challenges associated with introducing water as a medium between the projection lens and wafer. Resist process qualification is once again under the spot light.Due to the rapid introduction of immersion technology resist suppliers did not have sufficient time to reformulate their standard ArF resist processes to be compatible with water while at the same time satisfying critical imaging, etching and other requirements. For this reason a barrier (topcoat) had to be introduced in order to prevent resist leaching as well as to produce a more desirable surface for water to glide over. Introducing a top-coat created challenges for all parties involved: scanner manufacturers resist vendors and the end users. Since each manufacturer has its own unique technology for introducing immersion water, top-coat/resist processes needed not only to meet the end users' performance criteria but also meet each scanner manufacturer's requirements. Therefore material screening process and process evaluation became an important factor in immersion technology processes. Defectivity became the primary criterion for the resist process.The responsibility of the scanner manufacturer is twofold: first, to produce a system compatible with many different resist processes while not introducing additional defects, and second, to give resist manufacturers clear and concise requirements for achieving performance. In this paper we show how we have met the industry's needs in this area. First, we discuss the importance of material screening, including requirements for hydrophobicity, leaching, and peeling. Second, we present defectivity and other experimental data from practical materials that fulfill all requirements. Cases will be shown wherein an immersion process using commercially available resist processes introduces no additional defects. Several of these now do not require a topcoat. We therefore show that the industry's needs have been met with both topcoat and topcoat-less processes.

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