This Small Business Innovation Research (SBIR) Phase I project identifies an opportunity to advance the state of the art of ultra-precision fabrication precision by an order of magnitude or more compared to current capabilities. A significant problem with modern multi-axis ultra-precision fabrication is the lack of overall system closed loop control, requiring instead calibrated open-loop control which is unable to reach nanometer precision. The research objectives in this project open the opportunity for higher precision by designing and simulating a real time in-situ metrology system, including optics and algorithms, to achieve 5 nanometer x, y, z root mean square precision over a 6 inch planar substrate. The research is based on jointly designing an array of wavefront sensors, algorithms, commercially available processing hardware and specialized cooperating targets to provide real-time position feedback to a modern diamond turning/milling machine. The anticipated technical results are optical designs, algorithms matched to hardware, array geometries for wavefront sensing, specialized reference object designs and system simulations for real-world performance and proof-of-concept.
The broader impact/commercial potential of this project is demonstrated by a dramatic increase in the precision of ultra-precision fabrication and the competitive advantage inherent in such capability. The innovations in this project will enhance scientific and technological understanding of a wide field of view nanometer precision metrology system that will be used to enable fabrication of devices with tolerances not previously achievable. Fabrication of higher precision devices provides new optic/photonic devices, smaller and more reliable micro-mechanical systems and more durable yet increasingly inexpensive consumer goods. Nanometer precision in-situ measurement provides the ability to work faster and more consistently while also enablingg "re-work". The societal and commercial impacts of higher precision components produced in less time with more consistency extends beyond the devices and affects the way people interact with business opportunity and communication, family needs and education, and creates new forms of mobility and entertainment. Commercial advantage is providing ultra-precision fabrication with the highest precision in the world while also having the ability to remove, re-mount, and re-work components. Higher precision impacts every technology area and market sector that relies on technology fabrication, and future unknown markets that are enabled by higher precision.
This project identifies an opportunity to advance the state-of-the-art of ultra-precision fabrication precision by an order of magnitude or more compared to current capabilities. A significant problem with modern multi-axis ultra-precision fabrication is the lack of overall system closed-loop control, requiring instead calibrated open-loop control, which is unable to reach nanometer precision in actual dynamic systems. The research objectives in this project open the opportunity for higher precision by designing and simulating a real time in-situ metrology system, including optics and algorithms, to achieve 5 nanometer x, y, z root mean square precision over a 6 inch planar substrate. The research is based on jointly designing an array of wavefront sensors, algorithms, commercially available processing hardware and specialized cooperating targets to provide real-time position feedback to a modern diamond turning/milling machine. The anticipated technical results are optical designs, algorithms matched to hardware, array geometries for wavefront sensing, specialized reference object designs and system simulations for real-world performance and proof-of-concept. The intellectual merit of this work is in revealing the possibility to advance the state-of-the-art of ultra-precision fabrication precision by an order of magnitude or more compared to current capabilities. The broader impacts of the proposed activity are demonstrated by a dramatic increase in the precision of American-based ultra-precision fabrication and the competitive advantage inherent in such capability. The innovations in this project will enhance scientific and technological understanding of wide field of view nanometer precision metrology systems that will be used to enable fabrication of components with tolerances not previously achievable. Fabrication of higher precision components provides new optic/photonic devices, smaller and more reliable micro-mechanical systems and more durable yet increasingly inexpensive consumer goods. Nanometer precision real-time in-situ measurement provides the ability to work faster and more consistently while also enabling "re-work". The societal and commercial impacts of higher precision components produced in less time with more consistency extends beyond the devices and affects the way people interact with business opportunity and communication, family needs and education, and creates new forms of mobility and entertainment. Commercial advantage is improved when American ultra-precision fabrication is the highest precision in the world while also enabling the ability to remove, re-mount, and re-work components. Higher precision impacts every technology area and market sector that relies on technology fabrication, and future unknown markets that are enabled by higher precision. The primary research activities involved numerical simulation of the influences of CMOS sensor noise, along with the joint design of a generalized Shack-Hartmann (GSH) optical system, specialized reference marks, localization algorithms and processing systems. Base optics and signal processing were designed and 2x1, 3x3 and other multi-aperture systems were simulated. Algorithm loading and system accuracy were studied and simulated via Monte Carlo simulations that included optics, DSP, and reference marks. Algorithms and processing hardware were balanced to use off-the-shelf sensors and computers to minimize influence of electronics on stability of the milling volume. Illumination was simulated as dark field scattering and difficulties in background illumination were investigated in an experimental setup. An experiment comparing the precision of a capacitance gauge displacement measurements to localization with an imaging system was also evaluated for illumination issues and temporal processing using inexpensive imaging sensors. Overall the goal of 5nm RMS precision was not achievable in the application investigated. For diamond turning better than 50nm RMS precision is a more reasonable goal with 35nm being demonstrated in this work using equipment and operating conditions representative of a milling environment. The issues that improve precision include small feature reference marks and low-noise signal processing. Custom objectives with engineered point spread functions (PSFs) will enhance performance compared to off-the-shelf optics. The goal of achieving 5nm RMS simulated precision over 6" substrate was not directly reached in this work due to practical noise limitations of inexpensive CMOS imaging systems and limitations on the overall precision of the simulation environment. This does not preclude the ability to adapt this work to useful application in precision diamond turning. Metrology precision of 35nm is currently being demonstrated with an inexpensive imaging system in a non-laboratory environment suitable for fabrication of optical parts. The optical designs and Abbe projection errors indicate that multi-channel large working distance imaging systems with narrow instantaneous fields of view could be ideal configurations. These types of specialized multi-channel systems can be produced using current fabrication technology and would be invaluable in Phase 2 to implement closed-loop control diamond turning and milling. Localization computation in Phase 2 can be performed in real-time based on simulated 3x3 micron-sized objects which can be fabricated on the surfaces of the work piece. Modifying an existing high precision diamond turning/milling machine with a real-time ultra-precision in-situ metrology system in Phase 2 is feasible and with better than 50nm precision such a machine would provide more than 10x in improvement in precision compared to current machines.
