Electron-optics method for high-throughput in a SCALPEL system: preliminary analysis

Abstract A likely technology to supplant optical tools for the manufacturing of sub-0.13 μm design rule ICs is one based upon SCALPEL ® (SCattering with Angular Limitation Projection Electron-beam Lithography). One serious barrier to the acceptance of any lithographic technique by the IC manufacturing community is an inability to provide economically viable wafer throughput levels. Using a simple, parametric, time-utilization model of a step-and-scan writing strategy, we have identified the areas of greatest influence on throughput in a SCALPEL system. Though issues such as stage speed, resist sensitivity, and space charge-limited beam current do constrain the problem, we have found that the effective size of the printing field is the most sensitive parameter for realizing high throughput levels in SCALPEL. In this paper we present an electron-optical method for attaining high-throughput in a SCALPEL-based exposure tool. Starting with a moderately large area beam (1 mm × 1 mm) at the mask plane and simple, telecentric reduction (4x) optics, we have investigated increasing the effective printed field size through a combination of beam deflections, image stitching, and dynamic corrections. A preliminary analysis of recent modeling results indicates that a 3 mm × 3 mm effective field size at the wafer can be achieved while maintaining beam blur within manageable limits. The extensibility of this electron-optical approach to a production-worthy level of wafer throughput is presented, including the potential impact on other system parameters.