Fully-scaled 0.25-micron bipolar technology using variable shaped electron-beam lithography

Abstract

The successful application of sub-micron scaling principles to device fabrication involves an integration of tool, resist system, and process control. The precision overlay capability of a modified IBM EL-3 variable shaped beam lithography tool has been used to achieve optimized scaling of a 0.25 micrometers bipolar technology. Although the total device size is strongly coupled to linewidth control and overlay accuracy for all circuit levels, the overlay between the emitter opening and the shallow trench isolation is considered to be the most critical. We report on the integration of an advanced electron beam lithography and resist process capability with an innovative bipolar device technology to achieve emitter coupled logic (ECL) delays of 20.8 ps at a switching current of 1.1 mA. These results demonstrate the feasibility and performance leverage that can be accomplished through the aggressive scaling of conventional bipolar technologies.