We have measured the transparencies of a number of candidate resist materials for 157 nm, with an emphasis on determining which chemical platforms would allow resists to be used at maximum thicknesses while meeting requirements for optical density. Although ideal imaging is usually obtained at an optical density between 0.1 and 0.3 and values in excess of 0.5 can often result in nonvertical wall profiles, we chose to arbitrarily choose 0.4 as the maximum tolerable optical density. Using this analysis, our findings show that all existing commercially available resists would need to be Ͻ60 nm thick, whereas specialized hydrocarbon resists could be made ϳ100 nm thick, and new resists based on hydrofluorocarbons, siloxanes, and/or silsesquioxanes could be engineered to be used in thicknesses approaching 200 nm. We also assess the tradeoff between these thicknesses and what current information exists regarding defects as a function of resist thickness.
Lithography at 157 nm is rapidly emerging as the industry-preferred technology for the post-193 nm era. Its target application is for the 100 to 70 nm generations, and it is therefore widely viewed as a “bridge” technology before the next-generation lithographies are ready for insertion into manufacturing. Its attractiveness stems from the overlap in many areas with current practice and shared infrastructure developed for longer wavelengths. This article will review the present status of 157 nm lithography, emphasizing the technological challenges in the various subsystems: lasers, optical materials and coatings, photomask materials, photoresists, and projection tool development. Viewed as a whole, recent developments in these diverse areas are cause for cautious optimism that indeed 157 nm lithography will be ready in time, without encountering unforeseen obstacles.
Photodeposition of organic films on transparent substrates irradiated in the presence of trace levels (ppb to ppm) of hydrocarbons has been experimentally investigated and a model is presented that describes the film growth behavior. The efficacy of a given organic precursor at forming a deposit is proportional to the product of its surface coverage (as governed by its partial pressure relative to its saturation partial pressure) and by its photon absorption cross section. These measurements are important in predicting the transmission characteristics of lithographic optics operating at 1 57-, 193-, and 248-nm wavelength. For example, a lens element irradiated continuously for one year (1 kHz, 0.1 mJ/cm2 per pulse) in the presence of 1 part per billion of t-butyl benzene would exhibit a transmission of 87% at 193 nm. The effects of oxygencontaining ambients are also documented, and methods for elimination andlor prevention of organic contamination are suggested.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.