No one knows what the next, best way to build electronic circuits will be. That said there’s no shortage of efforts to invent something beyond current lithography. Oak Ridge National Laboratory, perhaps not surprisingly, is in the thick of the race and two recent studies from ORNL researchers showcase promising but very different approaches.
One method suggests phase change in a single complex oxide material may allow “creating” circuit elements much smaller than in today’s CMOS process while a second study puts STEM (scanning transmission electron microscopy) to work directly writing tiny patterns in metallic “ink,” forming features in liquid that are finer than half the width of a human hair. Articles describing both are posted on the ORNL web site.
- Phase Change. “Within a single piece of material, there are coexisting pockets of different magnetic and/or electronic behaviors,” said ORNL’s Zac Ward, the study’s corresponding author. “What was interesting in this study was that we found we can use those phases to act like circuit elements. The fact that it is possible to also move these elements around offers the intriguing opportunity of creating rewritable circuitry in the material.”
- STEM Direct Write. “We can now deposit high-purity metals at specific sites to build structures, with tailored material properties for a specific application,” said lead author Raymond Unocic of the Center for Nanophase Materials Sciences (CNMS), a DOE Office of Science User Facility at ORNL. “We can customize architectures and chemistries. We’re only limited by systems that are dissolvable in the liquid and can undergo chemical reactions.”
There are exciting prospects in both studies. In the first, because the phases respond to both magnetic and electrical fields, the material can be controlled in multiple ways, which creates the possibility for new types of computer chips. This study, “Multimodal Responses of Self-Organized Circuitry in Electronically Phase Separated Materials, was published today in Advanced Electronic Materials
“It’s a new way of thinking about electronics, where you don’t just have electrical fields switching off and on for your bits,” Ward said. “This is not going for raw power. It’s looking to explore completely different approaches towards multifunctional architectures where integration of multiple outside stimuli can be done in a single material.”
The second work, Direct-write liquid phase transformations with a scanning transmission electron microscope, published in August in Nanoscale (Royal Society of Chemistry), describes an automated process that’s controlled by weaving a STEM instrument’s electron beam through a liquid-filled cell to spur deposition of metal onto a silicon microchip. The patterns created are “nanoscale,” or on the size scale of atoms or molecules.
The current resolution of metallic “pixels” the liquid ink can direct-write is 40 nanometers, or twice the width of an influenza virus. In future work, Unocic and colleagues would like to push the resolution down to approach the state of the art of conventional nanolithography, 10 nanometers. They would also like to fabricate multi-component structures.
Links:
Link to ORNL article Complex materials can self-organize into circuits, may form basis for multifunction chips, https://www.ornl.gov/news/complex-materials-can-self-organize-circuits-may-form-basis-multifunction-chips
Link to first study, “Multimodal Responses of Self-Organized Circuitry in Electronically Phase Separated Materials, http://onlinelibrary.wiley.com/doi/10.1002/aelm.201670048/full
Link to ORNL article, New electron microscopy method sculpts 3-D structures at atomic level: https://www.ornl.gov/news/new-electron-microscopy-method-sculpts-3-d-structures-atomic-level
Link to second study, Direct-write liquid phase transformations with a scanning transmission electron microscope, http://pubs.rsc.org/en/Content/ArticleLanding/2016/NR/C6NR04994J#!divAbstract