Scanning stepper

02/01/1997

Scanning stepper

Designed for mass production of 256-Mbit DRAMs and next-generation microprocessor chip layers at 0.25 ?m and below, the FPA-4000ES1 krypton fluoride excimer-class scanning stepper expands the standard exposure field to 25 ? 33 mm, increases depth of focus, and extends resolution for a range of process layer conditions. This is made possible - without pattern dependency - by the CQUEST II quadrupole illumination mode, an innovation in off-axis illumination. Vibration Isolation Structure (which subdues vibrations from synchronous scanning motion) and independent reticle and stage all-axes air-bearing guide systems give the 4000ES1 an overlay accuracy of 70 nm. This stability, combined with a high-output KrF excimer laser and illumination system, provides throughput of 80 wafers/hour. Another advanced feature of this stepper is a system for combined laser pulse energy and pulse interval control, assuring reliable exposure dose stability for each 25 ? 33-mm field. Canon USA Inc., Lake Success, NY; ph 214/830-9600.