Raymond A. Adomaitis - US grants

; R o o t E n t r y F W g C o m p O b j b W o r d D o c u m e n t O b j e c t P o o l 3 g 3 g - . / 0 1 2 3 4 5 6 7 F Microsoft Word 6.0 Document MSWordDoc Word.Document.6 ; 9527576 Krishnaprasad This award is the University of Maryland with a sub-contract to North Carolina State University at Raleigh. The overall goal of this effort is to demonstrate a methodology for sensor-integrated control of rapid thermal chemical vapor deposition (RTCVD) of polycrystalline silicon (poly Si) from silane with focus on controlling deposition thickness and across-wafer uniformity. The project exploits advances in real-time sensors, including pyrometry for temperature, thermal imaging for temperature uniformity, and sampling mass spectrometry for thickness metrology and process ambient monitoring. Reduced-order process models constructed from high fidelity heat and fluid flow simulations, together with physically-based dynamic equipment, process, and sensor simulations, are the basis for control models. Resulting run-to-run control methodologies for controlling deposition thickness and across-wafer uniformity are being developed and validated experimentally, and real-time control approaches are being explored. These run-to-run control approaches will be extendible to real-time c ontrol. An architecture to support a basic supervisory control component is being demonstrated, using physically-based dynamic simulation to determine sensor signatures of specific equipment failure modes, together with advanced algorithms as interference tools for detecting sensor signal correlations and identifying indicated equipment/process malfunction. The investigators at the University of Maryland provide the effort on simulation and control, while the investigators at North Carolina State University provide the effort on sensors and on rapid thermal chemical vapor deposition of polycrystalline silicon. The experimental proof of concept of the control system will be performed in the cluster tool deposition apparatus at North Carolina State University. *** 0 0 Oh +' 0 $ H l D h , \\CLM15\SMURPHY$\WWUSER\TEMPLATE\NORMAL.DOT S u m m a r y I n f o r m a t i o n ( , 9527576 SHERONDA MURPHY SHERONDA MURPHY @ X g @ @ X g @ Microsoft Word 6.0 2 ; e = e d d l l l l l l l 1 % D T G 9 l l l l l l l l l s 9527576 Krishnaprasad This award is the University of Maryland with a sub-contract to North Carolina State University at Raleigh. The overall goal of this effort is to demonstrate a methodology for sensor-integrated control of rapid thermal chemical vapor deposition (RTCVD) of polycrystalline silicon (poly Si) from silane with focus on controlling deposition thickness and across-wafer uniformity. The project exploits advances in real-time sensors, including pyrometry for temperature, thermal imaging for temperature uniformity, and sampling mass spectrometry for thickness metrology and process ambient monitoring. Reduced-order process models constructed from high fidelity heat and fluid flow simulations, together with physically-based dynamic equipment, process, and sensor simulations, are the basis for control models. Resulting run-to-run control methodologies for controlling deposition thickness and across-wafer uniformity are being developed and validated experimentally, and real-time control approaches are being explored. These run-to-run control approaches wi

0082381
Adomaitis

We propose to develop the computational framework that will make possible a rapid proto-typing approach to simulator development for microelectronic device fabrication process systems. This research is intended to fill the gap that exists between supercomputer-based, highly resolved simulations and lumped-parameter models, a range currently spanned by specialized methods for process simulation, analysis, model reduction, and parameter estimation - numerical tools that are generally incompatible with each other. The proposed approach to process simulation is based on developing computational elements that have a one-to-one correspondence to the steps taken when implementing high-dimensional projection, spectral filtering and advanced weighted residual methods, such as the reduced basis and nonlinear Galerkin projections. Methods for assessing model validity; solution analysis (e.g., stability), and discretization error will be addressed in this framework. Indeed, because of its reliance on parameter estimation methods, an absolute measure of reduced-model predictive power always will be produced in this simulation framework. These interconnected computational tools will be developed in the MATLAB environment, taking advantage of MATLAB's object-oriented programming features to simplify simulations of complex systems and to create a pathway to incorporating our simulation tools in spectral element and other commercial software packages.

The need to generate computationally efficient, validated simulations for improving across-wafer processing uniformity in chemical vapor deposition and other semiconductor materials manufacturing unit operations provides the primary motivation for this research. Reduced models are suitable for real-time and run-to-run control, efficient process recipe optimization, and model-based sensing and estimation of unmeasurable processes, such as microfeature evolution. This proposal will support the joint research between the PI and the Tecbnology CAD group of Intel through a graduate student internship aimed at testing the simulation tools in a corporate research environment. The basic elements of this approach also will be developed in the context of a commercial chemical vapor deposition (CVD) cluster tool located at the University of Maryland, with the goal of producing a validated, reduced model to be used for wafer temperature prediction and conformal CVD studies.
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Abstract - Adomaitis - 0085633

An exploratory research program is planned to design a chemical vapor deposition (CVD) reactor that will enable across-wafer spatial control of deposition characteristics. An existing CVD reactor will be modified and used to generate data for developing a detailed simulator for reactor design and operation. The goals are to evaluate the actuation capabilities of this programmable reactor and establish its process simulation, optimization, sensing, and control requirements. The research is expected to demonstrate proof of concept for an entirely new mode of CVD processing.

Specific tasks will include:
(1) Proving a new concept for CVD reactor design that will demonstrate spatially controllable reactant delivery to the wafer: This will enable across-wafer uniformity to be achieved at virtually any process design point desired for material performance or manufacturing throughput. It will also allow intentional, programmed non-uniformity to reduce cost and time in process development.
(2) Developing object-oriented simulation-based design, analysis, optimization, and process control tools for the programmable CVD reactor system.
(3) Establishing a prototype for the next generation of CVD reactors for use in a materials development environment for conducting combinatorial CVD studies to rapidly evaluate new processes and materials.
(4) Demonstrating a concept in semiconductor processing equipment design that can be extended to other important manufacturing processes, including plasma-enhanced CVD, reactive ion etching, and possibly liquid-phase processes such as wafer cleaning and plating.

Research:

The purpose of this small Information Technology Research (ITR) project is to develop a new paradigm for semiconductor manufacturing equipment - flexible equipment design enabled by information technology. The current paradigm of fixed equipment design limits performance of equipment in a rapidly changing technology environment, where tradeoffs must be made between product performance and manufacturing efficiency. The concept is based on procedures where process conditions can be spatially programmed to (1) decouple manufacturing constraints (e.g., uniformity across large wafers) from product performance (e.g., material quality); (2) reduce experimentation time by enabling parallel, combinatorial experiments on each wafer; and (3) provide the basis for a flexible, extendible equipment technology. Work has already begun on an experimental test bed (chemical vapor deposition in a manufacturing cluster tool) using a physically based simulation of the prototype system. This project is for developing the IT infrastructure required to link object-oriented simulation and model reduction methodologies to web-accessible experimental data archives and physical property databases to techniques for real-time control of parallel and multiplexed sensor/actuator arrays.


Impact:

The project has the potential to fundamentally change the design paradigm of a major industry - semiconductor-manufacturing equipment - to one that directly exploits a broad spectrum of information technology. Integration of research and education are planned on a number of fronts: (1) the project provides an opportunity for interdisciplinary teaming (e.g., between engineers and computer scientists and between materials engineers and systems engineers) in the classroom, (2) using spatially programmable equipment design as the project focus in a materials/systems project course at the graduate level, and (3) developing simulation-based learning software for technicians and engineers in industry.

ABSTRACT

PI: Raymond A. Adomaitis and Gary W. Rubloff
Institution: University of Maryland
Proposal Number: 0554045
Title: The Nearest Uniformity Producing Profile (NUPP): A Generalized Optimization
Criterion for Thin-Film Processing Applications

The development of a new criterion for spatial uniformity control in thin film deposition processes (e.g., chemical vapor deposition for semiconductor manufacturing) is planned, applicable to any film quality (thickness, composition, microstructure, and electrical properties, among others) for all deposition systems where the substrate is rotated to improve uniformity. The approach is based on identifying the subspace of all deposition profiles on the stationary substrate (e.g., stalled wafer) that produce uniform films under rotation and then projecting a deposition profile to be controlled onto a sequence of uniformity-producing basis functions spanning that subspace to determine the Nearest Uniformity Producing Profile (NUPP). This mathematical criterion depends only on the geometrical characteristics of the deposition system, and control and optimization methods can be developed to reduce the deviation from the NUPP giving a universally applicable film control methodology. An important contribution of the NUPP concept and underlying theory is that the latter reveals new structure in the uniformity and
nonuniformity producing subspaces, providing insight into thin-film process design and control principles and an opportunity to unify these principles across a range of reactor designs.

Intellectual Merit

The research would develop a completely new approach to the control of thin film processing and demonstrate its effectiveness in an industrial setting. Preliminary research on the development of this new analysis and control technique has revealed open issues in terms of the mathematical and computational aspects of the framework, and the long standing relationship of the PI with the industrial partner creates an ideal situation for testing this control approach.

Broader Impact

A unique aspect of the uniformity control technique is that it is based on a minimal number of physical assumptions, resulting in a technique applicable to any uniformity criterion in a wide range of thin film processing control, optimization, and design applications, including all CVD, etch, PVD (physical vapor deposition), atomic layer deposition (ALD), and any other thin film process with a rotating substrate, giving the technique very broad industrial impact. Thin film processing in semiconductor, optoelectronic, optical coatings, and other industries will benefit from this approach. The majority of funding will be dedicated to providing undergraduate and graduate research opportunities in a state-of-the-art industrial research and production facility; the computational tools to be developed will be ideally suited for packaging and broad distribution in the format of a MATLAB toolbox and an associated short course.

The conversion of solar energy into solar fuels provides long-term storage and transport of the world?s most abundant but intermittent source of energy. In the transition from fossil fuels to hydrogen as an energy carrier, materials science will play an unprecedented role. Significant materials challenges exist in the production and storage of hydrogen related to development of renewable hydrogen energy based technologies. This joint effort between the University of Maryland and the Dayalbagh Educational Institute in Agra, India, implements a systematic study focusing on design, synthesis and evaluation of inexpensive, abundant and stable transition metal oxide semiconductor materials, hematite, titania and copper oxide, with end applications in photoelectrochemical production of hydrogen. The team brings together expertise in nanomaterials synthesis and characterization (US/India), and photoelectrochemistry (India). The objective is to improve the state-of-the-art for this class of photoactive materials through careful integration of synthesis, characterization, and simulation, and to use this basis for substantial fundamental advances in materials design.

Through scientific exchange, as well as exchanges of personnel, the team develops significant intellectual infrastructure for materials research, as well as optimizes use of instruments and facilities at each of the partner institutions in this international collaboration. Beyond the laboratory, recognizing that advances in materials science will not be translated into improved quality of life without a well-trained scientific and engineering workforce, the multidisciplinary and multinational team and the timely topic of materials for hydrogen generation will attract and retain more students in the science, technology, engineering and mathematics (STEM) pipeline.

This award is co-funded by the NSF Office of International Science and Engineering.

CBET-0828410
Adomaitis

Since the original demonstration of photo-assisted water electrolysis by Fujishima and Honda in 1972, tremendous effort has gone into developing photoelectrochemical (PEC) materials and systems. Numerous research programs have focused on improving the efficiency of these devices, and of those that have been successful, few have addressed the issue of whether such devices would be practical or environmentally desirable to manufacture on the scale necessary to impact the US's energy requirements.

The PIs plan to develop new semiconductor materials and solar cell devices for the production of hydrogen by the PEC decomposition of water with a manufacturing and product lifecycle perspective. The PEC materials development program builds directly on the complementary skills of the project PIs: the Adomaitis group's combinatorial chemical vapor deposition (CVD) reactor designs for material property and manufacturability optimization, and the Ehrman group's expertise in developing nanostructured films of doped copper oxide for PEC applications by flame synthesis and other manufacturing techniques.

Intellectual Merit:

The intellectual merit is defined in terms of three specific technological challenges to be addressed. The first consists of an approach to semiconductor thin-film processing: the PIs plan to demonstrate model-based combinatorial CVD for rapid development of semiconductor materials of optimal efficiency for PEC applications. The second goal is to efficiently investigate, by single-substrate design-of-experiment procedures, the complete range of nanostructured CuO1 film performance, particularly as a function of film morphology. Finally, they will apply the validated process simulators developed in this experimental/computational proposal to investigate the feasibility of using current commercial CVD reactor systems as a means of shortening the path to commercialization of our PEC devices.

Broader Impact:

The outcomes of this research program have the potential to broadly impact green manufacturing and energy production technologies. The production of H2 from the solar-powered splitting of water constitutes a sustainable energy supply in that the solar devices are to be manufactured from abundant and benign precursors with virtually no manufacturing waste products. This solar hydrogen production approach will integrate naturally into solar energy systems that enable more efficient use of the full solar spectrum.

The three educational initiatives will bring new technological and economic aspects of solar energy production into the classroom. A major capstone design project is planned where senior chemical engineering students will evaluate the economic potential of large-scale H2 production based on the semiconductor materials developed in the research.

With new energy, electronics, and consumer product applications, and the emergence of highthroughput reactor designs, Atomic Layer Deposition (ALD) is set to become a major thin-film manufacturing tool. Deposited using an alternating sequence of exposures to gas-phase precursors that would otherwise spontaneously react, ALD allows for the controlled deposition of a wide range of ultra-thin films at relatively low temperatures and potentially perfect conformality. Despite the upsurge in ALD process and equipment development, research on modeling deposition mechanisms and reaction kinetics in particular, continues to lag efforts devoted to new precursor chemistries and reactor designs. Because ALD is by its essential nature a completely dynamic process with no equivalent to steady-state deposition, the objective and primary intellectual merit of this proposal is to develop physically based models describing both ALD reaction rates and the changes occurring on the growth surface using transition-state (absolute rate) theory concepts. To achieve this objective, we identify three distinct subprojects to be pursued in this proposal:

1. Transition state rate model development for both reference and industrially relevant ALD reactions, combined with efficient numerical techniques to compute limit cycle solutions corresponding to continuous ALD reactor operation enabling optimization of the cyclic process.

2. Development of micro- and nano-scale precursor transport models in the form of ballistic transport simulations coupled to the new surface reaction models, and spatial discretization techniques to simulate the time-evolution of the growth surface position.

3. Validation of the reaction kinetics and ballistic transport models using reactors of the proposal industrial partner and dissemination of the rate modeling methods to the ALD community. The basic surface science research, numerical techniques, and reactor process research necessary to address the research goals described will potentially have a broad impact by contributing fundamentally to thin-film process engineering. Likewise, the physically based modeling methods developed are intended to be distributed to the ALD research and development community, further accelerating the range of applications of this manufacturing technology. The proposed research program will offer a unique educational opportunity for the engineering graduate students involved, giving them exposure to the scientists and engineers developing the next generation of ALD processes at Cambridge NanoTech.

Furthermore, with support of this proposal, the PI will continue to develop hands-on demonstrations of the products of thin film engineering which will be used for middle- and high-school level outreach programs.

The 9th World Congress of Chemical Engineering will be held August 18-23, 2013 in Seoul, Korea. To increase the presence of US researchers at the Congress, this proposal seeks support to offset the travel expenses of approximately 20 US faculty who will participate as speakers. It should be noted that all of the speakers invited by the PI have strong ties to the Process and Reaction Engineering division of CBET.

The invited speakers consist of two main subgroups:
1. The twelve to fourteen speakers making up two new reaction engineering sessions organized for the World Congress by the PI and Dr. Maria Burka;
2. An additional group of process systems faculty invited by the PI, selected to add a strong systems component to already established sessions at the World Congress.

Intellectual merit: The reaction engineering sessions will focus on computational, energy, and environmental aspects of reaction engineering, as well as microchemical systems and modeling the interaction of reaction and transport mechanisms. Furthermore, the sessions on sustainability, energy, and process safety will receive a substantial benefit from our invited systems-oriented speakers, bolstering the quantitative aspects of these important ChE research areas. The PI has invited a mix of early-career and more established speakers with an emphasis on the junior faculty who stand to improve their international presence by participating in this conference.

Broader impact: The exchange of ideas and current trends in Chemical Engineering research between the US, Korean, and other international participants has the potential to broadly impact the Congress participants. US participants supported by this travel grant will benefit from Congress themes that include university-industry cooperation and chemical engineering education. The proposal PI will encourage speakers supported by this travel grant to participate in publishing their work in the special issue of Chemical Engineering Science that will be devoted to the World Congress.

1438375
PI: Raymond Adomaitis
Institution: University of Maryland College Park

Some electronic materials, such as photovoltaic materials for solar cells, are manufactured in specialized chemical reactors in which gas-phase reactant molecules deposit on a surface to form a thin film of the product material. The routes that molecules take from the gas phase to the thin film involve a complex set of chemical reactions that must be well understood in order to produce materials with the desired properties. To describe mathematically the overall process of film growth, a system of equations can be derived to track the various chemical species inside the reactor and on the surface of the growing film. This project involves developing new methods for analyzing the system of equations, and comparing the results of the analysis with experimental data for deposition processes such as atomic layer deposition (ALD) and chemical vapor deposition (CVD). The results of the project will provide scientists and engineers with a new tool for predicting the performance of ALD and CVD reactors. The project will provide a training ground for graduate students in an important area of reaction engineering and will provide research opportunities for interested undergraduate students as well. Software that is developed during the project will be made available to the research and industrial communities.

This project will investigate the mathematical structure of differential-algebraic (DAE) systems of equations describing surface reaction species during ALD and CVED thin film deposition processes. A reaction network factorization procedure will be developed that partitions surface reaction and deposition species dynamic balances into sets of relatively slow (deposition), fast (equilibrium), and instantaneous (conserved) modes. The project will determine conditions under which the factorization works, the importance of fixed points of the equations, and reaction fluxes of chemical species. Example deposition processes of varying complexity will be analyzed, including some with spatially distributed deposition. Results that correlate rates of film growth with reactor conditions will be compared with experimental data.