Lithography’s endgame: the last wavelength and Moore’s Law 2.0

Abstract

The extraordinary success story that is Moore’s Law required many technological components to come together at the right times. This tutorial will tell this story through the lens of one of the key components: the patterning materials, in particular the photoresists. Every chip ever produced has used some form of microlithography, usually photolithography, which has historically been the gating technology for how quickly features sizes could be shrunk. Starting with cyclized rubber resists, the industry went on to use DNQ Novolak systems for a quarter century, before switching wavelengths from near-UV to 248 and 193 nm, then to 193 nm immersion. Every one of these switches required the invention of a new photoresist platform, new resin systems and even new imaging concepts, such as the use of chemically amplified resists beginning with 248 nm. For the materials scientist, Moore’s Law has historically been a race to the next wavelength. This sequence of more or less frantic developments is coming to an end as we near the physical limits of microlithography. With the introduction of EUV lithography, the finish line of this race is in sight: today’s EUV resists are still far from perfect, and this presentation will cover their issues and the paths forward, but there can be no doubt that with EUV, we have reached what appears to be the Final Wavelength. However, the need for better, faster, cheaper process options will not go away, and bottom up technologies such as DSA, selective or self-aligned patterning, and other processes with atomic level precision will need to continue to be developed. The future will see new non-CMOS device types and possibly even circuits which function according to the laws of relativistic quantum physics, all of which will require new materials and bring new challenges. While photolithography is entering its end game, the job of the material scientists is far from done. The presented manuscript is a slide deck, not a formal SPIE conference proceedings paper.