Soft X-rays for deep sub-100 nm lithography, with and without masks

The development of micro- and nanofabrication, their applications, and their dependent industries has progressed to a point where a bifurcation of technology development will likely occur. On the one hand, the semiconductor industry (at least in the USA) has decided to develop EUV and SCALPEL to meet its future needs. Even if the semiconductor industry is successful in this (which is by no means certain) such tools will not be useful in most other segments of industry and research that will employ nanolithography. As examples, MEMS, integrated optics, biological research, magnetic information storage, quantum-effect research, and multiple applications not yet envisioned will not employ the lithography tools of the semiconductor industry, either because they are too expensive, insufficiently flexible, or lacking in accuracy and spatial-phase coherence. Of course, direct-write electron-beam lithography can meet many of these non-semiconductor-industry needs, but in other cases a technique of higher throughput or broader process-latitude is necessary. Our experience at MIT in applying low-cost proximity x-ray nanolithography to a wide variety of applications leads us to conclude that this technology can provide an alternative path of a bifurcation. A new projection lithography technique, zone-plate-array lithography (ZPAL), does not require a mask, can operate from UV to EW to x-rays, and has the potential to reach the limits of the lithographic process.