Tokyo, Japan-- Tokyo Electron Limited (TEL; Head Office: Minato-ku, Tokyo; President & CEO: Kiyoshi Sato) today announced its agreement with Nikon Corporation (Head Office: Chiyoda-ku, Tokyo; President: Teruo Shimamura) to engage in joint development of liquid immersion exposure technology as it relates to exposure systems.

As semiconductor devices continue to increase in speed and integration, manufacturers of semiconductor production equipment are accelerating their development efforts. In the field of lithography, development of the next generation of exposure systems is underway. Proposals are also being made for lithography processes that use ArF exposure systems, the current leading-edge technology, to develop optical systems, resist materials, etc. to support even further miniaturization.

Since 2001, the two companies have been sharing their evaluation systems for joint activities to improve process performance. This new agreement marks a more advanced stage in this working arrangement.

Under the agreement announced today, TEL, with its large market share for resist coater/developer and advanced element technologies, and Nikon, with its leading-edge exposure technologies, will share their expertise in developing liquid immersion exposure technology, so as to complete the development of element technologies in a short time, with the goal of further extending the useful lifespan of ArF exposure systems.

The companies will verify these element technologies by the end of 2003, and aim to enter mass production as soon as possible, in order to meet the demand in the semiconductor industry for liquid immersion exposure technology as a manufacturer of semiconductor production equipment. The companies will also draw on the cooperation of various resist material suppliers, as resist is a key element of the lithography process, and thus promote the use of liquid immersion technology in practical application.

Liquid Immersion Exposure Technology

Normally, stepper resolution, R, is determined by the formula R = k x λ/NA, where k is the process coefficient, λ the wavelength of the light source, and NA the numerical aperture, indicating the brightness of the projection lens. The shorter the wavelength of the light source, and the larger the projection lens NA, the higher the resulting resolution. NA is given by the formula NA = n x sin θ, where n is the refractive index of the medium through which the exposure light passes, and θ the maximum incidence angle formed by the exposure light. Because normal exposure occurs in the air, n = 1. By contrast, liquid immersion exposure technology uses a liquid with a refractive index of n > 1 to expand the value of n in the definition of NA used in projection optics: NA = n x sin θ. With the same value for the exposure light's angle of incidence θ, the minimum resolution dimension can be improved, or reduced, to 1/n, helping increase the optical NA by a factor of n.

Meanwhile, using the same value of NA as before makes it possible to reduce the value of θ, with the result that the depth of focus can be improved, or enlarged, by factor n. Exposure using ArF laser light sources fills the space between the projection lens and wafer with purified water with a refractive index of 1.44. This method has traditionally been used with microscopes. In recent years, serious studies have commenced with regard to applying this method to liquid immersion exposure systems.

Note: This joint development is also being announced today by Nikon Corporation.

About Nikon

Nikon, established in 1917, is the first comprehensive and integrated optical and precision manufacturer in Japan. With a core of opto-electronics and precision technologies, a wide variety of products such as steppers, single-lens-reflex cameras, digital cameras, binoculars, microscopes, inspection instruments, measuring instruments as well as ophthalmic lenses are provided worldwide. It owns five production facilities in Japan and other domestic and overseas group production companies. Global sales, marketing and servicing activity under the Nikon brand are covered by its subsidiaries worldwide.