Next-Gen Nanoimprint Stepper Improves Defectivity, Alignment
EV Group announced its latest UV-NIL stepper in conjunction with SEMICON West, but the tool is mainly targeted at the latest micro-optical applications rather than next-generation semiconductor devices.
Aaron Hand, Executive Editor, Electronic Media -- Semiconductor International, 7/13/2009
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The EVG770 Gen II NIL Stepper is designed to address growing customer demands for improved pattern fidelity, greater process reliability and increased accuracy. (Source: EV Group) |
EV Group (EVG, St. Florian, Austria) kicked off its SEMICON West week with the launch of a next-generation UV-nanoimprint lithography (UV-NIL) step-and-repeat system, the EVG770 Gen II NIL Stepper. Targeted in particular at micro-optical applications such as the fabrication of microlenses for CMOS image sensors, the latest upgrades include improved pattern fidelity, greater process reliability and increased accuracy.
Although EVG is launching its latest UV-NIL tool around one of the biggest semiconductor manufacturing events of the year, the company's executives are not pinning their hopes on nanoimprint capturing a place in mainstream semiconductor manufacturing. Although the company is involved in the NILCom consortium, for example, to evaluate various aspects of NIL for producing semiconductor devices (including dual-damascene processes and contact hole layers), mainstream semiconductors cannot really be a focus, according to Thomas Glinsner, head of product management at EVG.
Instead, EVG is targeting micro-optical applications at the moment, he said, where there are already commercial markets. "For the semiconductor industry, the biggest hurdle is defectivity, alignment, and we don't want to compete with extreme UV at the moment because it makes no sense from a business point of view," Glinsner said.
Nonetheless, the Gen II stepper improves on both defectivity and alignment, through optical sensors and a non-contact bearing system, for example. Like the original EVG770, the new system operates in a vacuum environment with a spun-on polymer layer, which eliminates defect issues caused by trapped air bubbles. In addition, the Gen II tool includes:
• Optical sensors that align the stamp and wafer into perfect parallelism for contact-free wedge compensation.
• Chuck movement via a non-contact bearing system to reduce particle contamination.
• High-precision alignment system with accuracy within ±500 nm, and <35 nm overlay alignment accuracy demonstrated on a test set-up system.
• Load-cell measurement of embossing/de-embossing force, improving imprint uniformity and process reliability due to active force control and allowing for real-time, in situ characterization of various commercially available resists and anti-sticking layers.
• Flexible equipment automation levels.
• De facto template form factor to shorten the fabrication turnaround time.
• Capability to support a host of commercially available resists with varying viscosities to improve process flexibility for micromolding and nanopatterning.
Despite nanoimprint's relatively low cost, the semiconductor industry has shown reservations with the technology when it comes to defectivity levels, as well as alignment. EVG's 35 nm overlay measurement is a best case based on the use of optional fine alignment capability. Semiconductor manufacturing at the 32 nm would require alignment accuracy of ~10 nm, Glinsner noted. For other applications, however, such as the micro-optical applications mentioned, the 500 nm alignment would be sufficient, he added.
The micro-optics arena is a key market driver for UV-NIL adoption, using master lenses to develop working stamps for full-wafer lens micromolding of CMOS image sensors for wafer-level cameras and other end products. Complementing its single-step nanoimprint processes, EVG's step-and-repeat approach enables manufacturers to create a master that can then be replicated across the substrate to subsequently produce a full-wafer lens micromold.
The EVG770 is available now. "We will have two installations at customer sites this year, and I think that's quite a good start for this next-generation tool," Glinsner said.
One system will be installed at the Fraunhofer Institute for Applied Optics and Precision Engineering (IOF, Jena, Germany). As announced in May, Fraunhofer IOF will use the UV-NIL stepper for microlens mastering and molding for a range of micro-optics applications, as well as for other nanoimprinting applications. This equipment will be installed soon, according to Glinsner. Although he could not detail the other installation, it will go into R&D, he said, for targeted features of <100 nm.
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Man would I love to be on the install team. I wonder what sort of footprint and enery requrements it has? And how much it differs from a Semi etcher?
Frank Gesualdo - 7/14/2009 11:49:57 AM CDT -
NGL masks are too defect-sensitive. And these are small volume hard-to-find defects.
guest reader - 7/13/2009 11:19:35 PM CDT
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