Photomask specifications for advanced KrF and ArF lithography tools require improvements in both glass substrate quality and coating development. CD control and uniformity will be driven by transmission, index and birefringence uniformity of the substrate. Coating development will facilitate the use of advanced resolution enhancement techniques. Progress in the development of Corning’s HPFS blanks for advanced lithography applications is reviewed. A variety of new masking materials are being developed to complement HPFS including specialized absorber coatings with low reflectivity and phase shift coatings to enable attenuated phase-shift photomasks. The optical properties of these materials will be described.
We describe solid state gas microsensor array technology for real-time, low-cost environmental and industrial monitoring. The four-element, surface-micromachined arrays are designed in CMOS technology and consist of multiple platforms called 'microhotplates.' Each microhotplate can be individually addressed, and includes functionality for rapid control and measurement of sensor temperature and gas-induced changes in a sensing film's electrical properties. The array elements can be tuned for specific analytes, by choice of sensing material and the temperature-programs applied, in order to better meet the needs of a particular application. Tin oxide was used as the base sensing material for microhotplates used in these studies. Tin oxide is grown selectively on each individual element within the arrays using a chemical vapor deposition process involving thermal decomposition of tetramethyltin in an argon and oxygen ambient. Catalytic additives, such as Pt, Pd and Cu are surface-dispersed to make the films more selective and sensitive. Detection capabilities for the low power microhotplate sensing technology are being established for target analytes in ambients that are relevant to process control, environmental measurements, and vapor-related remediation studies. We describe the use of these micromachined arrays to detect approximately ppm levels of methanol, benzene and hydrogen in ambient air and to produce analyte-specific signatures using temperature programs, T(t).
In this work, micromachining and planar processing have been used to produce gas sensing devices with lower power consumption at lower cost. The small size brings new advantages for chemical selectivity as well: multi-element arrays whose time-varying signals can be interpreted using pattern recognition methods. The device platform is a `microhotplate,' consisting of a built-in heater, thermometer, and electrodes to probe the sensing films. Microhotplates are fabricated using CMOS-compatible technologies, enabling on-chip circuitry for multiplexing and signal amplification.
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