Yung-Cheng Lee - US grants

Lee This research addresses some key requirements for the design for manufacture of very small supercomputers used in intelligent machines such as portable robots. This multidisciplinary effort is centered on developing a compact rapid prototyping and manufacturing center. Microscale laser lithography, flip-chip soldering and robot controlled pick-and-place techniques are being used. Simulation studies validate the design before prototyping. Research is concentrating on the self-aligning mechanism with an emphasis on the reliability of solder joints, fuzzy logic modeling with focus on the process modeling and optimization, and further improvement of thermosonic bonding technology.

Studies are being conducted which if successful will demonstrate the feasibility of universities fabricating in a few hours their own low- cost prototype multichip modules (MCM). MCMs represent a state-of-the- art microsystems packaging technique, improving speed and power by factors of three or more. Current industrial MCM fabrication costs are prohibitive in prototype quantities to universities. The cost reduction and short turnaround time offered by this novel concept along with other fast prototyping methodologies have the potential to revolutionize microsystems design. The concept is to have standard pattern substrates mass produced by industry at low cost. Each substrate would have buried patterns of power and ground wiring, plus a buried level of signal wiring. All buried wiring would have strategically placed paths called vias to a surface layer. This surface layer would be a pattern of wiring including connections to the vias which could be cut by the universities to customize for a particular design. Pretested bare chips with solder bumps would be bonded to the customized substrate to form the customized module. The concept is being demonstrated by 1) designing, fabricating and testing the substrates and two types of memory MCMs, 2) functional design only of two other complex modules.

This research will focus on several issues critical to the development of the proposed quick prototyping system for multichip modules (MCMs). These issues are: 1) the detailed design of the workcenter; 2) the experimental demonstration of the accuracy and repeatability of two critical units in the workcenter--the photoplotter and the pick-and-place robot; 3) the evaluation of the solder joint's electrical resistance; 4) the complete description of the user-interface of the workcenter; (5) the electroless plating for single-chip solder bumping; and 6) the explicit comparison to MCC's QTAI and GE's High-Density Interconnect (HDI) alternative methods. Although the system is proposed for quick prototyping, the manufacturing requirements in these issues are being addressed. The requirements for manufacturing are more demanding than those for prototyping.

This grant is to help support a conference/workshop on photonic packaging. It is a follow-on to a wrokshop from a similar one supported by NSF one year ago. It was clear that packaging is a much more important subject than previously thought and the first workshop only scratched the surface. This year the topic areas to be discussed are: hybrid multi-chip integration and waveguide interconnects.

9413804 Johnson The term "smart pixel" refers to picture elements in a display or photodetector array that may have some or all of the following attributes memory, intra-pixel processing, inter-pixel communication, and optical I/O in the form of photodetectors and modulators or emitters. Smart pixel arrays (SPAs) evolved form passive-addressed spatial light modulators (SLMs) and displays. These devices sport "simple: picture elements consisting of material placed between two overlapping electrodes to modulate the amplitude, phase, or polarization of an optical wave front in response to the potential difference between the two electrodes. SLMs and displays with simple pixels suffer form low frame and refresh rates resulting in image degradation and ghosting, low resolution, and limited pixel functionality. By incorporating active circuitry at each picture element, so-called "smart pixel" arrays overcome many of the problems associated with their predecessors. Industrial interest in the project is high as Kopin Corporation, Boeing, Rockwell Sciences Center, RCA Sarnoff, Boulder Nonlinear Systems, Meadowlark Optics, Physical Optics Corporation , Ford Research Laboratories and Ball Communications are already working with the NSF/ERC for Optoelectronic Computing Systems (OCS) at the University of Colorado at Boulder (CU) to design and fabricate SPAs for applications ranging from micro displays to smart cameras for the intelligent vehicle highway system. These industries have funded, or have committed to fund approximately $322,471 per year in support of personnel and SPA fabrication cost. In addition, Photonics Research Incorporated, science Applications Incorporated and Hughes Aircraft have contracted with the Center for another $290,995 per year to investigate silicon backplanes to drive vertical cavity surface emitting laser for parallel, free-space optical interconnects. There are knowledge-based and technology-based issues that must be addressed to improve the quality and manufact urability of LCOS smart pixel arrays, thus insuring their eventual commercialization. The equipment requested in this proposal will establish the first comprehensive computer-aided design, planarization, and advanced manufacturing and packaging facility for smart pixel array technology. In particular, we propose to purchase with NSF and matching funds computer workstations with color graphics and color printers for a centralized smart pixel design laboratory, wafer polishing and metal deposition systems to planarize the processed die, and develop an automated robotic controlled packaging facility that will lead the way to a low-cost method of manufacturing SPAs. This world class facility will be used for research and research training of undergraduate and graduate students, research associates, faculty, and industrial researchers working in the field of micro display and smart pixel array design. Working SPAs will be cataloged in a library. Documentation will be provided that detail the operating characteristics of the design, including response time, responsivity (when photodetectors are used) and I-V curves where appropriate. One anticipated result of this project is the design of 1024X1180 and 2048X2048 smart pixel arrays for helmet mounted displays. These devices will project 6 bits analog and full color data. High density smart photodetector arrays for enhanced night vision will also be a focus of this research. Another major result anticipated from this project is producing planarized silicon backplanes, resulting in an optically flat surface for the liquid crystal modulator. Finally, an advanced manufacturing and packaging facility will produce a low-cost, robotic-controlled method for manufacturing SPAs.

This award provides funding for developing a new technology, called Thermosonic Bonding, for connections in electronic packaging applications. Such a technology and the knowledge base resulting from the studies will have a profound impact on solderless packaging technologies in manufacturing. The resulting technologies can also be useful to support prototyping facilities and education in manufacturing engineering. The technology can simplify the prototyping procedures for multichip (MCM) modules. Such technologies are critical to low-cost and environmentally sound prototyping and manufacturing methods.

9411619 Mickelson This proposal is for sponsorship of a small workshop to be held with approximately 25-35 participants from industry, universities, and government laboratories and agencies. All participants will be involved in optoelectronic packaging. The purpose will be to try to foster discussion between packaging researchers and students, from different mother disciplines, through having them discuss specific design problems in optoelectronic packaging. Graduate students will be encouraged to attend the workshop through travel support. Such non-classroom education will enhance students' experiences through group discussions and poster exchanges. ***

This project will build a new generation of numerical simulation systems by creating a feedback path between physical experiments and numerical solvers. There are a number of exciting implications of this data-adaptive simulation idea. Engineering fluid flows are inherently complex. This complexity limits measurement and precision, so engineers are forced to work with fluid flows based on very sparse information. Numerical solvers, on the other hand, can resolve tiny flow structures, but they generally run in an open-loop mode and are thus unverified. Coupling the two forms of technology offers powerful advantages to each. Comparisons against live experimental data will allow simulation algorithms to be verified quantitatively, in detail, and in-line. Once it is verified in this fashion, one can use the simulation with confidence on related problems. Once can also use the sensor information to correct the solver's data, or even to adjust the solver parameters on the fly. Moreover, once the solver is properly synchronized with the real system, one could use the former to explore the physics of the latter in more detail than sensors would allow - and still trust the results.

A particularly compelling application area for data-adaptive simulation techniques is microelectromechanical systems (MEMS). This emerging technology is driving a revolution in engineering design that is placing new demands on numerical simulation. Accurate modeling of the interaction of tiny, flexible, moving structures with high-speed chaotic fluids is challenging. To resolve the fine details in this kind of simulation, computational fluid dynamics technology requires extremely fine meshes and the solution of very large systems of nonlinear equations. This makes it difficult to build production-quality computer-aided design (CAD) tools for MEMS, which in turn forces engineers to fabricate devices without testing them. Functional CAD tools would allow MEMS designers to achieve one-pass design, much as VLSI does now.

CTS-0114109
Jean Hertzberg, University of Colorado

In this proposal, funding is requested to purchase a Particle Image Velocimetry (PIV) system to enhance the research capabilities of the PI and four Co-PI's. They are actively engaged in a number of interesting research problems in fluid mechanics. These include real time simulation and control of a two-dimensional jet, evaluation of micro-electro-mechanical systems (MEMS) fluidic devices, cardiovascular fluid dynamics, and infectious aerosol generation.

CBET-1246854
PI: Y. C. Lee (Univ. of Colorado)

Atomic layer deposition (ALD) and molecular layer deposition (MLD) are important thin film deposition processes based on sequential, self-limiting surface reactions. ALD and MLD can deposit conformal and ultrathin inorganic and organic films with atomic/molecular layer control. ALD was recognized as the transformative technology when ALD was added to the semiconductor roadmap over ten years ago. ALD and MLD have the potential to make an even more significant impact if their throughput and cost can be improved using roll-to-roll (R2R) processes. For example, ALD and MLD could be used to fabricate high quality gas diffusion barrier on polymers for organic light emitting diodes and thin film photovoltaics. ALD could also be employed to coat the electrodes of Li ion batteries to improve their capacity stability and greatly extend their lifetime. Laboratory results have already confirmed the excellent performance of ALD barriers and coatings. Transitioning these laboratory results to the market requires a rapid and cost-effective method to perform ALD and MLD on polymer or foil webs.

This project will build an R2R ALD/MLD testbed with process control for web speeds of up to 30 m/min. To accomplish this challenging goal, computational fluid dynamics modeling will be performed to understand ALD/MLD and support the systematic design of novel gas source heads for ALD/MLD on both flat and porous substrates. The gas source heads will be integrated with a R2R web handling machine and this new apparatus will be optimized using studies of in situ monitoring of thickness versus processing parameters. Reduced order models will be studied and applied to achieve optimal performance. In addition, new methodologies will be developed for web handling such as the placement of the gas source head in the region of web wrap on a roller. The interdisciplinary team will also work with ALD NanoSolutions, a local startup company. ALD NanoSolutions is currently developing an R2R ALD testbed to coat flat polymer web substrates. The team will also collaborate with the National Renewable Energy Laboratory, Sandia Labs, Formosa Plastic and Kent Displays for potential scale-up manufacturing.

R2R ALD/MLD nano-manufacturing will facilitate the commercialization of ALD/MLD for a large number of applications and help to restore U.S. manufacturing competitiveness. This research will also educate and train undergraduate and graduate students to perform original research in scalable nano-manufacturing. A new section on ALD/MLD-enabled systems will be introduced into a first-year mechanical engineering projects course. These projects will develop designs that will be used in the K-12 outreach programs. R2R manufacturing teaching modules will be also introduced into existing undergraduate and graduate courses. The results of this research will also be widely disseminated at various scientific meetings and through a project web site.