Reticle pattern generator writes 90-nm features; Midspan spectral inverter rebuilds signal

May 1st, 2003
Th 124815

Reticle pattern generator writes 90-nm features

An electron-beam-based reticle pattern generator creates features down to 90 nm in size at high throughput.
Click here to enlarge image

TOKYO—Engineers at JEOL have developed new electron-beam drawing apparatus for mass production of next-generation lithographic photomasks, or reticles, with features down to 90 nm (see figure). To aid with the miniaturization of semiconductor integrated-circuit elements, which are patterned at ever-shorter exposure wavelengths, demand has been increasing for reticles with finer resolutions. The new electron-beam apparatus makes possible high-resolution, high-throughput production of reticles by improving the electro-optic systems and material carrier systems and increasing the critical-dimension (CD) resolution and position resolution.

The electron-gun emitter uses single-crystal lanthanum hexaboride and has an acceleration power of up to 50 kV. The CD resolution is 8 nm (3s) and the position resolution is ±12 nm.

As the minimum feature size in large-scale integrated circuits gets smaller, the amount of information in photomasks increases. This new device copes with this increase in information by increasing data-processing speed and transmission speed by an order of magnitude, and by increasing the current density of the electron beam.

Courtesy O plus E magazine, Tokyo

Midspan spectral inverter rebuilds signal

TOKYO—Shinji Yamashita of the University of Tokyo Graduate School of Frontier Sciences has developed a low-noise wavelength-division-multiplexing application using a midspan spectral inverter (MSSI) with a high-efficiency nonlinear four-wave-mixing device.

Four-wave mixing involves pumping light of a different wavelength along with a signal being transmitted through an optical fiber. The result is that a new signal is generated with some properties opposite to that of the original signal. Usually, pulses degrade as they are transmitted along an optical fiber, with a decay distance dependent on the wavelength of the light. In this research, a wavelength-conversion device that can efficiently perform four-wave mixing was placed in the transmission path. The signal light was modulated in addition to the pump light. As a result, the signal-generation efficiency increased and the spreading of the spectrum was controlled. The receiving end could thus receive a good signal with little dispersion.

A midspan spectral inverter (MSSI) recreates the original shape of a degraded signal traveling down an optical fiber. As seen in "eye" diagrams, the signal as it enters the fiber is of good quality (left). At 100 km down the fiber, where the MSSI is located, the signal has degraded (center). At 203.8 km, or 103.8 km past the MSSI, the signal has regained much of its original quality (right).
Click here to enlarge image

A 1559.31-nm, 9.95328-GHz non-return-to-zero signal was transmitted over 203.8 km (see figure). The light was wavelength-modulated at a 100-km distance down the fiber. The pumping light for the four-wave mixing was 1554 nm, and 1548.69 nm after modulation. As a result of this setup, the signal waveform—which was temporarily deformed—was successfully restored to its original shape (see figure).

In this experiment, the spectrum-inversion properties of the optical fiber four-wave-mixing wavelength modulator were exploited. In the future, the wide bandwidth properties of this device will be used to create a pure wavelength modulator.

Courtesy O plus E magazine, Tokyo

More in Fiber Optics