S 204 B

The Nikon S 204 B is a stepper. The Nikon NSR-S204B is a scanner exposure system for photolithography. The Nikon NSR-S204B uses a 248 nm wavelength, a 4:1 reduction ratio, and a maximum numerical aperture of 0.68. The Nikon NSR-S204B is configured for 6 inch reticles and 300 mm wafers. The Nikon NSR-S204B has a 25 x 33 mm2 field size.^{[3][2][1][5][4]}

The Nikon NSR-S204B uses a projection lens with 4:1 reduction imaging. The Nikon NSR-S204B uses software controlled variable numerical aperture from 0.55 to 0.68. The Nikon NSR-S204B uses a KrF excimer laser light source at 248 nm. The Nikon NSR-S204B is equipped with a standard beam matching unit. The Nikon NSR-S204B includes Laser Step Alignment and Field Image Alignment. The Nikon NSR-S204B includes a real time focus and level sensor, chip leveling, and MAC real time lens control. The Nikon NSR-S204B includes an air bearing wafer stage with linear motors, a robotic wafer loader Type III, non contact prealignment, and a Nikon standard reticle loader.^[1][5][4]

Lithography tools are used after wafer preparation steps such as film formation and photoresist coating. Lithography exposure is followed by post exposure bake, development, and then a pattern transfer or modification step such as etch or implant. Repeated lithography cycles are used throughout device fabrication to define successive layers.