Deep UV (DUV) lithography is being applied to pattern increasingly finer geometries, leading to solutions like double- and multiple-patterning. Such process complexities lead to higher costs due to the increasing number of steps required to produce the desired results. One of the consequences is that the lithography equipment needs to provide higher operating efficiencies to minimize the cost increases, especially for producers of memory devices that experience a rapid decline in sales prices of these products over time. In addition to having introduced higher power 193nm light sources to enable higher throughput, we previously described technologies that also enable: higher tool availability via advanced discharge chamber gas management algorithms; improved process monitoring via enhanced on-board beam metrology; and increased depth of focus (DOF) via light source bandwidth modulation. In this paper we will report on the field performance of these technologies with data that supports the desired improvements in on-wafer performance and operational efficiencies.
High performance lithography is increasingly demanding light sources to deliver laser light over a much larger range of
stabilized bandwidths. The applications range from improved optical proximity correction (OPC) to the high-speed
printing of vias and contact holes, through a process called focus drilling. Several advances in light source technology
must integrate to provide the improved bandwidth performance required by the industry.
This paper will outline three of the core technologies developed by Cymer and integrated into its most advanced XLATM
and XLRTM series light sources to meet this need. Novel improvements in line narrowing offer the actuation necessary
to tune the bandwidth over the large range. Advanced bandwidth metrology yields accurate measurements of the
bandwidth over the wide range. And new controls and feedback algorithms provide the integration to stabilize the
bandwidth to the desired target. The result provides laser light bandwidths that can be tuned to and accurately stabilized
at any spectral E95 target from 0.3 pm to 1.6 pm, while maintaining all other laser performance parameters. The feature
is called focus drilling. Focus drilling extends the utility of Cymer XLA and XLR lasers by adding more flexibility to
the light source, allowing the end-user chipmaker to select the exact properties of the laser light necessary for a wider
range of process steps.
The article will discuss the above technologies and emphasize their important aspects. It will also highlight some of the
key performance aspects using data from Cymer's testing. Some of the design features and trade-offs will be provided,
and a few of the relevant metrics will be presented and justified. Finally, potential future improvements to the
technology will be presented.
Double patterning lithography places significant demands not only on the optical performance of the light source
(higher power, improved parametric stability), but also on high uptime in order to meet the higher throughput
requirements of the litho cell. In this paper, we will describe the challenges faced in delivering improved
performance while achieving better reliability and resultant uptime as embodied in the XLR 600ix light source from
Cymer, announced one year ago. Data from extended life testing at 90W operation will be shown to illustrate these
improvements.
The ability to extend deep ultraviolet (DUV) lithography into the 32 and sub-32nm domain has more recently relied
on improvements in source-mask optimization (SMO), double patterning (DP) and complex, pixellated illumination
patterns. Yet these techniques require a commensurate improvement in the light source that powers the latest
generation scanners in order to enable high performance at high throughput. This paper will show detailed
performance results of the latest-generation light source from Cymer that incorporates flexible power with dramatic
improvements in dose, wavelength and bandwidth stability.
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