ASML, Canon, Nikon take dip into immersion litho

ASML, Canon, Nikon take dip into immersion litho
SANTA CLARA, Calif. — During the SPIE Microlithography conference here today (February 27, 2003), ASML Holding NV, Canon Inc., and Nikon Corp. separately disclosed they are taking the first steps in what could be the next "breakthrough" in chip production: immersion lithography.

One of the big announcements was made by the Rochester Institute of Technology (RIT), which disclosed that it has received funding from ASML, International Sematech, and the Semiconductor Research Corp. (SRC) to develop technologies based on immersion lithography. RIT also disclosed it has developed two internally-developed, immersion scanners, capable of printing 70-nm (half-pitch) images.

Japan's Nikon also stunned the audience at SPIE, by announcing that there are "no showstoppers" to prevent the development of 193-nm tools based on immersion techniques. The company also claimed to have printed 65-nm lines based on the technology.

And not to be outdone, Canon has quietly formed an internal "task force" to investigate the feasibility of the technology. Like ASML and Nikon, Canon is also working with Sematech on the technology.

Imersion lithography could be a major breakthrough in chip production "if it is feasible," declared Phil Ware, senior fellow of lithography strategy of Canon, in an interview with SBN.

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.

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 over conventional projection lithography.

Chip-making consortium Sematech recently held a workshop on immersion lithography technology and undertook to perform a feasibility study on six-month time-frame.

Sematech will report its findings in mid-2003, although some are already dismissing the technology. "The technology is more than not ready," said Peter Silverman, Intel Fellow and director of Intel Corp.'s lithography capital equipment operations, in a recent interview.

Still others believe the technology is viable, but there are some major challenges as well. "We think immersion offers some significant challenges," said Bruce Smith, associate dean in the college of engineering and Intel Professor at RIT.

"Bubbles are a big problem," he said in a presentation during a large audience at SPIE. Smith was referring to one of the top showstoppers in immersion. Simple water bubbles could potentially form on the lithography lens, which could disrupt the exposure process in chip production, he said.

In an interview after the event, Smith said RIT has received an undisclosed amount of funding from ASML, Sematech, and SRC. Asked if Intel was funding the project, Smith said that Intel is involved by way of its relationship with SRC.

With the funding, RIT has devised two internally-developed, 193-nm scanners, equipped with a laser source and an immersion-oriented lens. The first R&D tool is a 193-nm unit, with a numerical aperture of 1.30. The second is a small-field tool with a NA of 0.6.

"We're doing experimental lithography," he told SBN. "The limitation of our tool is 70-nm half-pitch lines."

Meanwhile, Nikon has been able to demonstrate 65-nm lines on a 193-nm exposure tool, based on immersion techniques, said Soichi Owa, manager of 157-nm and immersion development at Nikon of Tokyo, in a presentation at SPIE.

Owa also declared that there are "no showstoppers" with the technology, although Nikon is still in the R&D stage with immersion. "We are doing a feasibility study," he told SBN after the event. "We are mainly researching 193-nm tools for the 65-nm node."

Owa also said that 157-nm tools with immersion could be extended down to 40-nm. The developments have prompted Nikon to move into the second stage of its feasibility study with the technology, he said.

Asked when the first commercial tools based on immersion would likely appear in the market, the Nikon researcher said it would take at least "more than two years."