With conventional optical technologies, the diffraction limit makes it impossible to achieve beam diameters smaller than half the wavelength of the light source. But, using near-field light — light generated around the irradiated material — enables the formation of extremely small beam spots that are unaffected by the diffraction limit.

Canon has developed a metal film with through-pores and grooves of 100 nm or smaller and is conducting research on lithography technologies to use this film as a photomask. Producing near-field light on the mask surface and using this light for exposure makes it possible to create resist patterns of 1/10 or less the width of the wavelength of the light source.

Canon is working to develop this near-field mask exposure technology with the aim of applying it to next-generation lithography tools capable of micropatterning on the order of several tens of nm without the need to use large-scale equipment. Development of near-field optical technologies also holds the promise of applications for optical-recording and micro-optical devices.

Conventional optical technologies employ propagating light to see images and process objects. Even if such light is focused using lenses, its diffraction limit makes it impossible to create a beam with a diameter smaller than the light's wavelength.

An alternative to propagating light is near-field light. When an object is illuminated, near-field light is created within a range of approximately 100 nm around its periphery. However, this near-field light is generally mixed up with the penetrating and diffusing rays of the propagating light. More effort is needed to effectively isolate and utilize the near-field light.

Propagating Light and Near-Field Light

Propagating Light

Near-Field Light

Propagating light has the property of traveling long distances. Near-field light is light that escapes from localized areas like "droplets" and this leaking light can be observed by opening a tiny hole smaller than the wavelength of light in a metallic film.