Hybrid lithography: The marriage between optical and e-beam lithography. A method to study process integration and device performance for advanced device nodes

Abstract

Moore's law continues to prescribe ever smaller device dimensions with each new device node. While the new device nodes are scheduled at even pace, the innovation required to obtain commensurate device performance is greater with every device node. This increased complexity in the process, while maintaining the momentum of Moore's law, is increasing the pressure on the development teams to increase the learning rate on new processes and their interactions. There have been many publications on mix-and-match lithography to enable early learning. In this technique, one whole device level (often the gate definition) is replaced by a different technology (often e-beam), while all the other levels continue to be patterned using traditional optical lithography. Hybrid lithography, by contrast, is the use of different lithography technologies on a single resist level which enables the marriage of both technology's best properties. In this work, we present hybrid e-beam direct write and optical lithography, enabling high throughput (optical), high-resolution (EBDW), excellent overlay (EBDW) and fast prototyping (EBDW). We will show how IBM has used hybrid lithography to enable early learning on back end of the line (BEOL) processes and on extremely scaled SRAM cells (0.143 μm2) [D.M. Fried, et al., IEDM Proceedings (2004) 261-264]. © 2006 Elsevier B.V. All rights reserved.