PREVAIL - IBM's e-beam technology for next generation lithography

PREVAIL - Projection Reduction Exposure with Variable Axis Immersion Lenses represents the high throughput e-beam projection approach to NGL which IBM is pursuing in cooperation with Nikon Corporation as alliance partner. This paper discusses the challenges and accomplishments of the PREVAIL project. The supreme challenge facing all e-beam lithography approaches has been and still is throughput. Since the throughput of e-beam projection systems is severely limited by the available optical field size, the key to success is the ability to overcome this limitation. The PREVAIL technique overcomes field-limiting off-axis aberrations through the use of variable axis lenses, which electronically shift the optical axis simultaneously with the deflected beam so that the beam effectively remains on axis. The resist images obtained with the Proof-of-Concept (POC) system demonstrate that PREVAIL effectively eliminates off-axis aberrations affecting both resolution and placement accuracy of pixels. As part of the POC system a high emmitance gun has been developed to provide uniform illumination of the patterned subfield and to fill, the large numerical aperture projection optics designed to significantly reduce beam blur caused by Coulomb interaction.