IMEC-ASML Present 193 nm Results
Staff -- Semiconductor International, 4/1/1999
Early results on 193 nm
lithography processing were presented by the Inter-University Microelectronics
Centre (IMEC, Leuven, Belgium) and ASM Lithography (ASML, Veldhoven, The
Netherlands) at the Annual Research Review Meeting at IMEC. The results
demonstrated that ASML's 193 nm ArF laser step and scan system has imaging
capabilities for 100 nm research and development. It has been shown to be
compatible with pilot line production of integrated circuits using 130 nm device
design rule generations and beyond. This system will become operational in the
first half of the year in a special 193 nm lithography facility, which is
adjacent to the IMEC pilot line where manufacturers will be able to gain
experience. Most of the work is being done at ASML, while process development
and optimization work goes on at IMEC.
Luc Van den Hove, vice president of the Si Process Technology Division at IMEC, said 193 nm lithography needs tremendous R&D efforts. The time taken for 248 nm lithography to be used in production took far longer than anticipated, ~20 years. The acceleration of the SIA roadmap, under pressure from the microtechnology companies, means that 0.13 µm (130 nm) lithography will be needed well before the year 2003, leaving less than four years to production. The number of scanners is very limited, partly due to the restricted supply of calcium fluoride optics of the required quality. ASML is producing lenses in calcium fluoride for wafers of up to 200 mm diameter, and lenses for 300 mm wafers are under development.
IMEC has built up a worldwide consortium of companies that will convey the technology to their own fabs. In 1998, the program attracted a number of industry partners. In addition, mask shops, equipment suppliers and resist manufacturers have joined the project.
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Fig. 1. These 130 nm lines were fabricated without any enhancement technique using a numerical aperture of 0.63. |
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| Fig. 2. This single isolated line structure is 90 nm wide. |
- A 193 nm resist evaluation program, in which wet and dry developed resists from all of the major resist vendors, will be continuously evaluated and bench-marked.
- Detailed exposure tool assessment will be made in pilot line production. Imaging quality, reliability, up-time and cost of ownership will be studied. Special attention will be given to the lifetime and stability of optical elements.
- Enhancement techniques, including phase shift masks, off-axis illumination and optical proximity correction, will be studied to determine the ultimate resolution and process latitude extension obtainable using the 193 nm wavelength.
- Lithography process development will initially concentrate on the 130 nm technology node, with a later extension to the 100 nm node.
Structures fabricated very recently without use of enhancement techniques show a resolution down to 120 nm using binary masks and 80 nm isolated lines using alternating phase shift masks. High aspect ratio 130 nm lines (Fig. 1) were produced with a 500 nm depth of focus and full field dynamic distortions below 20 nm. Enhancement methods have been used to produce a 90 nm isolated line on a silicon substrate (Fig. 2). These are believed to be the best results obtained on a full field scanner. Van den Hove said 193 nm lithography will be used down to at least 100 nm, because no competitive technology is likely to be ready in time to meet demand.
