Lithography for Terascale Electronics

Lithography is recognized as the key technology pacing the evolution of microelectronics and the introduction of nanoelectronics. Projection optical lithography has provided many generations of improvements in feature size, overlay accuracy, and throughput, and will continue to do so for several more generations. Whereas there is no consensus whether optical lithography (as we know it) will reach 150, 130, or 100nm, there is a reasonable agreement that extensions of existing technology will not meet the lithography requirements of the 100nm generation and beyond, needed beginning in the middle of the next decade. The Network for Advanced Lithography thus brings together four University teams to research possible approaches to lithography at 100nm and beyond.
The primary task of this Network is to identify, evaluate, characterize, and advance promising (potentially production worthy) approaches to lithography for the generations requiring feature sizes at or below 100nm. The research aims to work on the most difficult technological challenges facing every candidate lithography approach and investigate various approaches to overcome these challenges. For example, in EUV lithography the Network Research is concerned with ultimate resolution limits inherent in the technology, with the very challenging metrology requirements in optic characterization, and with the problem of verification of defect levels in EUV mask. In E-beam lithography, the concerns are fundamental limits in overlay capability, and throughput limits, both stemming directly from the use of charged particles. There is no significant effort within the Network on x-ray lithography, owing to the large industrial and university programs already in place on that technology.
A major focus of the Network is to research maskless lithography. Whereas the technical challenges are huge, the potential payoff is enormous, compelling a broad, open-minded effort. Radical new approaches to lithography offer significant cost savings or throughput increase because of simplicity and parallelism. Projects are underway on scanning proximal probes, parallel arrays of e-beams, and arrays of x-ray spots focused by zone plates. Several other approaches are at an earlier stage of investigation.
The Network also includes key infrastructure research: metrology, resist technology, and the CAD tools needed to design and analyze the advanced technologies under investigation for candidate lithography approaches.