Wet and wild
By By Peter Clarke and Mark LaPedus
12/05/2003 2:00 AM EST
URL: siliconstrategies.com
The race in immersion lithography has officially begun, as rivals ASM Holding NV and Nikon Corp. separately made major announcements over the last week.
As reported, Nikon said it will begin selling production immersion lithography tools by 2006. The Japanese equipment giant is set to have an alpha machine ready by the second half of 2004, allowing customers to engage in evaluations of immersion lithography at the Nikon facilities in Tokyo (see December 1 story).
Meanwhile, ASML officially rolled out its initial immersion tool and announced that foundry giant Taiwan Semiconductor Manufacturing Co. Ltd. ordered the first system here (see December 3 story). And not to be outdone, Canon Inc. of Japan is also working on the technology.
In immersion lithography, the space between the projection lens and the wafer is filled with a liquid. Immersion technology could offer better resolution enhancement and higher numerical apertures (NA) over conventional projection lithography. The technology could potentially extend 193-nm tools down to 45-nm and possibly below--thereby pushing out 157-nm and extreme ultraviolet (EUV) tools, according to analysts. Some believe that 157-nm scanners with immersion could process devices at 32-nm and below, according to analysts.
Production immersion tools are being currently targeted to process devices at linewidth geometries of below 65-nm, said Geoff Wild, chief executive of Nikon's U.S. subsidiary, Nikon Precision Inc., based in Belmont.
At present, the immersion lithography race among vendors is still too close to call. ASML and Nikon, along with Canon, are still separately in the R&D stages and have yet to develop a production-worthy immersion tool, according to analysts.
However, saying it will eventually take the leadership position in the market, Nikon claims it is neck-and-neck--or slightly ahead--in immersion over lithography-tool rival ASML right now. "We're ahead or level," Wild said. "We intend to be first in the market," he said in an interview with Silicon Strategies.
Based on its announced schedule, Nikon plans to develop an "engineering evaluation" model in the second half of 2004, with a "pre-production" system due in 2005 and a production tool in 2006.
Wild believes Nikon's stated timetable is a bit conservative. "I would not be surprised if we can do better than that," he said. "Our position is that there are no show stoppers in immersion."
The Nikon executive also believes that the technology faces some challenges, especially on the marketing side of the equation. For years, chip makers have used conventional optical lithography in production fabs and the shift towards wet or immersion is a radical jump.
One of the issues is that "a lot of companies are skeptical about immersion," he said. Several chip makers, including Intel, STMicroelectronics, have expressed doubts about immersion. Still others, such as TSMC, are moving full speed ahead with immersion tools.
Initially, Nikon will develop an engineering immersion tool, based on its NSR-S307E line of 193-nm scanners. The projection lens for this machine will have a NA of 0.85.
Then, in 2005, Nikon will ship a "pre-production" immersion model, with a projection lens NA of 0.92. The company will begin selling production systems with production NA of 1.0 in 2006.
Dutch treat
Meanwhile, Dutch lithography equipment maker ASML said Wednesday (December 3, 2003) that the Twinscan XT:1250 scanner has been successfully converted for use in immersion lithography and is available to be ordered from the company.
The announcement, made at the Semicon Japan exhibition, came after hints from Doug Dunn, president and chief executive officer, and a briefing given to financial analysts (see November 13 story).
The Twinscan XT:1250i makes use of 193-nm wavelength light and has a lens system with a numerical aperture of 0.85. It is described as a pre-production lithography scanner and marks a step-up from the Twinscan AT:1150i, ASML's original immersion prototype which has a relatively low numerical aperture of 0.75.
When discussed with financial analysts back in November ASML said that the 0.85 NA version of its Twinscan would likely ship to customers in the fourth quarter of 2004.
Immersion lithography at 193-nm wavelength puts a film of water between the lens system and the wafer. Because of closer match between the refractive indices of the lens system and water, as opposed to air, it is believed that an improved depth of focus and superior resolution to dry lithography systems can be achieved at the same wavelength.
ASML has adapted its established Twinscan scanner to immersion so that wafer measurement, including focus and overlay, is completed in the dry stage while the imaging process, using immersion fluid applied between the wafer and the lens, is completed in the other.
The company said that only slight lens modifications are required to convert a Twinscan machine to immersion.
"ASML marks its technology leadership with another industry first - the first ever pre-production immersion system. Our customers and the market have long debated the benefits of 157-nm versus immersion technologies. With the introduction of the XT:1250i, ASML has committed itself to be the only company that delivers both. Customers have their choice," said Dunn in a statement.
The XT:1250i is the immersion version of ASML's recently announced Twinscan XT:1250 (see October 21 story). Both systems operate at the 65-nm manufacturing process node with half-pitch resolution at 70-nm.
The XT:1250 is geared for advanced production, while the XT:1250i allows customers to test and qualify immersion processes, ASML said.
The pioneer
As expected foundry chipmaker Taiwan Semiconductor Manufacturing Company Ltd. (TSMC) was the first company to commit to immersion lithography.
ASML said Wednesday (December 3, 2003) at the Semicon Japan exhibition that it has received its first order for an immersion lithography system and it has come from TSMC.
TSMC was revealed to be pursuing an immersion lithography strategy when it was reported cancelling orders for multiple 157-nm wavelength lithography machines back in October.
The tool TSMC has ordered is ASML's Twinscan XT:1250i with delivery scheduled for the third quarter of 2004. No financial details of the sale were disclosed.
The 1250i is an adaption for ASML's previously announced Twinscan XT:1250 which operates using 193-nm wavelength light and has a lens system with a numerical aperture of 0.85.
Immersion lithography, replaces the air between the wafer and the lens with a denser fluid to improve depth of focus and extend the use of a given optical wavelengths to higher resolution. The market for immersion lithography tools could reach $230 million by 2005, ASML said.
"ASML is committed to delivering the right tool, to the right customer at the right time. We are pleased that TSMC selected ASML's Twinscan systems to enable their immersion technology program," said Dunn. "Many of the chip manufacturers with whom we work are interested in immersion as it provides an alternative solution to support their roadmaps and enriches their investments. ASML is pleased to have the technology and know-how to make immersion a commercial reality."
"Immersion technology will increase the process window of our most advanced applications. The XT:1250i allows TSMC to start using immersion technology in a manufacturing environment," said Burn Lin, senior director of TSMC's micropatterning technology division, in the same statement.
TSMC is set to use the XT:1250i to test and develop immersion technology as a volume manufacturing solution, ASML said. |
