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Lithography vendors unveil next-gen scanners

Posted: 13 Jul 2006 ?? ?Print Version ?Bookmark and Share

Keywords:lithography? immersion scanner? 45nm? Semicon West? Nikon?

The bell has sounded for leading-edge lithography vendors, which are coming to market with next-generation immersion scanners for the 45nm node and beyond. Many will enter the arena at this week's Semicon West trade show in San Francisco, California.

Enabling the next wave of chip designs, Japan's Nikon Inc. recently unveiled a 193nm immersion lithography scanner that is equipped with a hyper-numerical-aperture (NA) projection lens, rated at 1.3.

Rival ASML Holding NV is expected to unwrap details of a yet-to-be-announced 193nm immersion lithography system dubbed the XT:1900i, sources said. Not to be outdone, Japan's Canon Inc. is expected to disclose the details of its initial immersion lithography system, sources added.

The "big three" lithography suppliersASML, Canon and Nikonseparately claim the technical leadership position in the immersion lithography market, although the race is still in the early stages and too close to call, according to analysts.

In immersion lithography, the space between the projection lens and the wafer is filled with water. Immersion technology is expected to offer a better depth of focus over conventional, "dry" lithography scanners. The technology could potentially extend 193nm tools down to 32nm, according to analysts.

While immersion lithography is slowly making its way into production fabs, there is a growing concern about the cost-of-ownership issues associated with the newfangled systems.

In the mid-1980s, chipmakers were stunned when a lithography tool broke the $1 million price tag barrier. By contrast, current 193nm immersion lithography machines cost up to $28 million per unit. Sources believe the next-generation, hyper-NA systems will approach $40 million each.

Cost concerns
"Lithography is a concern for sure," Ajit Manocha, executive vice president, general manager and chief manufacturing officer for Philips Semiconductors, said in a recent interview. "The cost of these new tools is really a big concern."

One problem is that leading-edge chipmakers are stuck with immersion lithography at the 45nm "half pitch" node and perhaps beyond. The 193nm dry lithography tools currently in use are being extended down to the 65nm half-pitch node, but those workhorse tools are expected to run out of gas, according to analysts.

"People are committed to immersion," said Bernie Wood, director of marketing for Nikon's U.S. sales arm, Nikon Precision Inc. "I can say that major memory and logic vendors will all use immersion."

The initial drivers for immersion lithography are the NAND-based flash memory suppliers, namely Samsung Electronics Co. Ltd and Toshiba Corp. For example, seeking to scale its NAND flash devices, Toshiba plans to use its first immersion lithography tools in production at the 55nm node, which is expected to be deployed in early 2007, analysts said.

In contrast, Intel Corp. has publicly announced plans to use dry 193nm lithography tools at the 45nm node for microprocessor production. Intel's gate lengths are less aggressive than those of the NAND flash suppliers, a fact that enables the microprocessor giant to extend the dry 193nm scanners for at least another generation, analysts said.

Some believe Intel will deploy immersion lithography at the 32nm node. The company is evaluating machines from ASML, Canon and Nikon, but Nikon is said to have a slight edge. For the production of microprocessors, Nikon is Intel's main supplier of lithography tools, sources said.

Seeking to maintain its position at Intel and other accounts, Nikon recently rolled out the NSR-S610C scanner. The 193nm, 1.3NA immersion tool targets mass production of 45nm half-pitch-memory devices and 32nm logic chips.

The product represents a radical step for Nikon. Its previous-generation, NSR-S609C immersion tool had a hyper NA of 1.07 and was based on a refractive lens. The new immersion scanner features a catadioptric lens and Nikon's fourth-generation polarization technology, dubbed Polano.

Like the S609C, the S610C is based on Nikon's Local Fill Technology and its Tandem Stage design. The company said its proprietary Local Fill Technology eliminates scanner-induced immersion defects.

Nikon's Tandem Stage design utilizes two stages with different functions. That enables the system to achieve throughputs of 130 wafers or more per hour, according to Nikon. Alignment accuracy has been reduced to 6.5nm or less.

Systems will start shipping by the end of 2006. Nikon said that it has "commitments" for 20 S610C machines from customers throughout 2007. It also claims to have 15 orders for its previous-generation, S609C tool.

For 45nm production, Nikon says it has at least a "six-month" lead over ASML. "We shipped the first 0.85NA lens, the first 0.92NA lens and the first hyper-NA system, and now we'll ship the first 1.3NA system," said Geoff Wild, chief executive of Nikon Precision.

ASML disputed those claims. "Nikon is playing catch-up," said Peter Jenkins, vice president of marketing for ASML. "The [S610C] machine has not been shipped. It's a paper tiger."

ASML has already shipped a 193nm immersion scanner for 45nm chip production-far ahead of Nikon, Jenkins pointed out. In April, ASML shipped its previously announced XT:1700Fi, a dual-stage immersion lithography tool designed for volume 300mm wafer production at 50nm resolutions and below. The XT:1700Fi is based on a 1.2NA catadioptric lens.

Officials from Nikon claim that the ASML tool is slightly late to market. Nikon asserts that ASML has experienced some problems with the nozzle unit within the machine.

ASML disputed those assertions as well. "The [XT:1700Fi] is starting to ship into the market for production," Jenkins said. "That will ramp up into next year."

Industry sources predict that ASML will ship 20 to 25 immersion scanners in 2006. They believe the company will deliver 40 to 50 tools in 2007.

In other recent lithography developments, Cymer Inc. has unveiled what it claims is the world's first argon fluoride laser light source for 45nm "production" immersion lithography tools.

Cymer's XLR 500i is based on the company's Ring Technology. The approach enables an improvement in energy stability performance and a greater than 20 percent reduction in cost of ownership, as compared with previous-generation 193nm products, according to Cymer.

An improvement on Cymer's dual-chamber platform, the XLR 500i architecture replaces the conventional power amplifier stage with a recirculating ring technology. Further, the improved dose performance can also reduce the number of laser pulses consumed during the wafer exposure process, the company stated.

- Mark LaPedus
EE Times

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