Innovations in Scanning Tunneling Microscope Control

Systems for This project will develop a microelectromechanical system (MEMS) platform technology for scanning probe microscope-based, high-speed atomic scale High-throughput fabrication. Initially, it will be used to speed up, by more than 1000 times, today’s Atomically Precise single tip hydrogen depassivation lithography (HDL), enabling commercial fabrication of 2D atomically precise nanoscale devices. Ultimately, it could be used to fabricate Manufacturing 3D atomically precise materials, features, and devices. Graphic image courtesy of University of Texas at Dallas and Zyvex Labs Atomically precise manufacturing (APM) is an emerging disruptive technology precision movement in three dimensions mechanosynthesis (i.e., moving single that could dramatically reduce energy are also needed for the required accuracy atoms mechanically to control chemical and coordination between the multiple reactions) of three dimensional (3D) use and increase performance of STM tips. By dramatically improving the devices and for subsequent positional materials, structures, devices, and geometry and control of STMs, they can assembly of nanoscale building blocks. finished goods. Using APM, every atom become a platform technology for APM and deliver atomic-level control. First, is at its specified location relative Benefits for Our Industry and an array of micro-machined STMs that Our Nation to the other atoms—there are no can work in parallel for high-speed and defects, missing atoms, extra atoms, high-throughput imaging and positional This APM platform technology will accelerate the development of tools and or incorrect (impurity) atoms. Like other assembly will be designed and built. The system will utilize feedback-controlled processes for manufacturing materials disruptive technologies, APM will first microelectromechanical system (MEMS) and products that offer new functional be commercialized in early premium functioning as independent STMs that can qualities and ultra-high performance. Advancements may lead to a wide range markets, such as nanoelectronics for operate 100 to 1000 times faster than state- of-the-art systems and with sub-nanometer of high value energy-saving products, quantum computing. accuracy, improving the precision of including applications such as: diffraction writing atomic features on a surface while arrays with unprecedented optical One potential approach to fabricating performance, molecule-specific membrane atomically precise (AP) nanoscale protecting the STM tip in both imaging and writing modes. The speed and filters, catalytic surfaces, and improved devices is based on turning a scanning boiling interfaces for heat transfer. tunneling microscope (STM) used throughput will be increased to a rate that could enable industrial-scale fabrication of to image atoms into a tool for Applications in Our Nation’s manufacturing at the atomic scale. devices with nanoscale features. Today’s STMs work at speeds useful for This project’s initial approach to Industry imaging and writing but are too slow to STM-based APM is based on the only This technology is expected to have be commercially viable in manufacturing existing technology used to fabricate AP broad applicability and enable high- applications. The objective of this two dimensional (2D) devices—hydrogen throughput APM of devices. Initial research project is to speed up and depassivation lithography (HDL). industrial use could involve making improve STM control so large arrays of Today’s HDL uses a single tip to image nanoimprint lithography and roll-to-roll STMs can quickly and precisely fabricate and lithographically ‘write’ with atomic AP templates that can fabricate devices commercial quantities of AP materials, resolution. with previously unattainable electronic features, and devices. properties. The templates are an attractive Ultimately, high-throughput MEMS- high value market. Integrated circuit Multiple STM tips operating precisely based systems may also be used in metrology, photomask inspection, and in parallel require streamlined geometry conjunction with other scanning metrology systems integrated into roll- and increased control to achieve the high probe microscopes, such as an atomic to-roll manufacturing processes are all throughput necessary for commercial force microscope (AFM), to enable viability. STM nanopositioners with viable applications for such a system.

ADVANCED MANUFACTURING OFFICE ADVANCED MANUFACTURING OFFICE

Project Description Pathways Technology Transition The project objective is to build a The project will first design and fabricate Successful execution of this project will platform technology for high-throughput all the necessary prototype components complete the first step needed to make APM based on innovations that required to perform high-speed and AP 2D nanoscale devices commercially dramatically increase the speed and high-throughput HDL imaging and viable. In the long term, the technologies accuracy of STMs. The first innovation writing. These include a high-speed being pursued offer a path to developing is to use new MEMS actuators instead macroscale nanopositioner to enable controllable nano-mechanical systems. of the piezoelectric actuators currently implementation of high-speed scan In the short term, there will be the used in STMs. Piezoelectric actuators patterns; micro-machined MEMS STMs; opportunity to market individual are highly resonant systems that require and atomic force microscopy (AFM) technologies developed throughout this low-bandwidth (slow) controllers and micro-cantilevers with self-sensing and project, such as the MEMS STM and suffer from hysteresis and creep, which self-actuation functionalities. Feedback AFM. For example, a possible path limits their positioning precision. The control algorithms will be developed to for advancing the technology toward second innovation is to streamline the operate the system with high accuracy the marketplace would be UT-Dallas connection geometry to enable precise and with control loops to guarantee licensing the MEMS STM scanner and fast operation of arrays of multiple stability, robustness, and repeatability of technology to Zyvex Labs. Zyvex has STM tips to increase throughput. operation. successfully commercialized a number of Initially, the technology will be used to Subsequently, components will be complex nanotechnology systems in the make 2D devices with HDL on hydrogen- assembled resulting in a single tip past. terminated silicon. In this method, the system that can be tested in imaging and tip of an STM injects electrons into the lithography modes. At the conclusion Project Partners chemical bond holding the hydrogen of this project, the high-speed imaging University of Texas at Dallas atom to the silicon surface, causing capability developed will be used to Richardson, TX it to break. Each removed hydrogen determine an appropriate location for Principal Investigator: Dr. Reza is then replaced with a dopant atom. lithography, and the system will perform Moheimani This technique has been used to make HDL with atomic precision, with one Email: [email protected] single-electron transistors, quantum or several MEMS STMs operating Zyvex Labs dots with only a few atoms, and 2D simultaneously. Follow-up research Richardson, TX quantum metamaterials for research will demonstrate multiple tips that are purposes. HDL coupled with the needed for parallel operation. These National Institute of Standards and MEMS STM could lead to additive systems could be scaled up into one- or Technology manufacturing with atomic precision. two-dimensional STM arrays consisting Gaithersburg, MD The envisioned system will enable AP of hundreds of nanopositioners operating lithography at speeds and throughputs in parallel to enable high-speed and high- For additional information, 2-3 orders of magnitude beyond what throughput imaging and lithography. please contact is feasible with current technology. It Milestones Tina Kaarsberg, PhD will enable the programmable atomic- Technology Manager scale positional control needed to This three-year project began in 2018: U.S. Department of Energy fabricate the smallest building blocks • Develop new non-raster modes Advanced Manufacturing Office and the positional assembly of these of imaging for scanning probe Phone: 202-586-5112 building blocks into atomically precise microscopes and build a high-speed Email: [email protected] ■ systems and sub-systems to create more long-range nanopositioner (2019) complex atomic-scale electronic devices and systems. This multidisciplinary • Improve STM control system to enable project will combine innovations in new modes of HD lithography and mechatronic system design, feedback spectroscopy (2020) control, high-precision engineering, and • Demonstrate MEMS STMs and an microfabrication technologies to achieve array of high-frequency MEMS AFM the increased speed, throughput, and cantilevers (2020) accuracy necessary for commercially viable APM. • Demonstrate a closed-loop control system that can achieve a lateral Barriers bandwidth of 20 kHz, with the controller achieving a positioning • Achieving needed imaging speed, accuracy of ± 0.1 nanometer (2021) parallel operation of probes, and atomic-precision positioning

• Extreme multidisciplinary nature of the For more information, visit: project. energy.gov/eere/amo

DOE/EE-1842 • September 2019