ELECTRON-OPTICS METHOD FOR HIGH-THROUGHPUT IN A SCALPEL SYSTEM - PRELIMINARY-ANALYSIS

A likely technology to supplant optical tools for the manufacturing of sub-0-13 mu m design rule ICs is one based upon SCALPEL(R) (SCatterin g with Angular Limitation Projection Electron-beam Lithography). One s erious barrier to the acceptance of any lithographic technique by the IC manufacturing community is an inability to provide economically via ble wafer throughput levels. Using a simple. parametric, time-utilizat ion 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-limit ed beam current do constrain the problem, we have found that the effec tive size of the printing field is the most sensitive parameter for re alizing high throughput levels in SCALPEL. In this paper we present an electron-optical method for attaining high-throughput in a SCALPEL-ba sed exposure tool. Starting with a moderately large area beam (1 mm x 1 mm) at the mask plane and simple, telecentric reduction (4x) optics, we have investigated increasing the effective printed field size thro ugh a combination of beam deflections, image stitching, and dynamic co rrections. A preliminary analysis of recent modeling results indicates that a 3 mm x 3 mm effective field size at the wafer can be achieved while maintaining beam blur within manageable limits. The extensibilit y of this electron-optical approach to a production-worthy level of wa fer throughput is presented, including the potential impact on other s ystem parameters.