Toshiaki Shinozaki

Piezoelectrically Driven xyθ Table for Submicron Lithography Systems

A newly designed piezoelectrically driven XYθ table has been developed for submicron lithography systems. The XYθ table was fabricated using a monolithic plate structure, joined together with flexure hinges and driven by an inchworm function. This function involves the periodic clamping and unclamping of four blocks and the expansion and contraction of piezoelectric actuators. The XYθ table can travel a long distance with fine positioning in the X, Y, and θ directions. The velocities can be controlled up to 0.5 mm/s in the X and Y directions, and 0.3×10 −2 rad/s in the θ direction by changing the inchworm function stepping rate. Positioning accuracy of less than 1 μm in the X and Y directions, and 7.5×10−6 rad in the θ direction can easily be obtained using a servo system with a 0.5‐μm measuring resolution.

An electron beam image projection system with automatic wafer handling

Abstract A new electron beam image projection system has been developed for 0.5 μm lithography. The system features three newly-designed subsystems: a double Helmholtz-type superconducting magnet, an automatic wafer handling system and a mask-wafer alignment and parallelism control system. The system also has a high accelerating voltage operation capability. Practical resolution of 0.5 μm, wafer handling time of 120 seconds and alignment mark detection accuracy better than 0.03 μm in 0.1 seconds were attained.

Resolution and overlay precision of a 10 to 1 step-and-repeat projection printer for VLSI circuit fabrication

A step-and-repeat projection printer called NSR-2 has been developed for VLSI circuit fabrication. The NSR-2 exhibits high resolution due to projection optics with high numerical aperture (NA = 0.35), and high overlay precision resulting from both an off-axis alignment scheme and a supplementary through-the-lens (TTL) alignment scheme. The total overlay precision, using the off-axis alignment scheme, was found to be less than ±0.34 µm(2σ). Using the TTL alignment scheme, the value was improved to be less than ±0.26 µm(2σ). 1-µm resolution was obtained all over the 10-mm2image field. Practical resolution, which can be assured in a production line, was estimated, by SEM observation and MTF measurement, to be 1.2 to 1.4 µm.