Lithography History: Leading the Charge on Moore's Law (1988–2004)

The Chemical, Microsystem, and Nanoscale Technologies Group evolved from the Submicrometer Technology Group, which was formed in 1988. At that time, the smallest features patterned with optical lithography (at 248 nm) in commercial devices were 0.5 μm in size. By 2013, the smallest half-pitch used in the semiconductor industry was still patterned with optical lithography and was ~20 times smaller, 0.025 μm. Much of this remarkable extension of optical lithography can be traced back to the Submicrometer Technology Group's early work, which help to sustain this worldwide trend known as "Moore's Law" that saw the doubling of electronic circuit density every three years. ( full article)

Transition to Sensing : Unforeseen Lithography Challenge Forces Expansion of the Group's Capabilities (1993–2008)

Within a few months of installing the SVGL 193-nm step-and-scan system in the Microelectronics Laboratory in 1993, an unexpected problem arose: the image quality at the wafer plane had degraded considerably. Detailed analysis revealed that some of the optical surfaces were covered with a layer of contaminant, whose chemical composition or source was unknown. The Submicrometer Technology Group hypothesized that small amounts of volatile compounds present in the chamber were being photodissociated by the short-wavelength 193-nm radiation, leading to a soot-like deposit. Here was a new effect that could potentially be fatal to 193-nm lithography. It certainly had to be understood and fully resolved. ( full article)

Transition to Materials Synthesis (1993–2008): Materials Capability Established to Support Expanding Mission Breadth

It is clear that the semiconductor industry needs improvements in both exposure tool optics and photoresist performance in order to keep shrinking feature sizes. There can be no doubt that improvements in stepper optics have made major contributions to increased resolution. However, the impact of the other components of the lithographic process cannot be overlooked. The drive to explore every avenue to increase lithography resolution prompted Lincoln Laboratory to investigate new materials for photoresists tailored to be transparent at ever-shorter wavelengths, to explore chemical amplification as a new imaging scheme, and to develop nonaromatic systems with improved dry etch resistance for 193-nm lithography. Together, such process improvements have been as important as better optics and shorter wavelengths at sustaining Moore's Law. ( full article)


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