Publications
Semiconductor Digital Twin Workshop, SEMI December 4-5, 2023
This presentation explains how SC Solutions’ fast, control-oriented, physics-based models can be used as components of digital twins (DT) of semiconductor equipment. The standards document on digital twin framework for manufacturing (ISO 23247*) defines a digital twin (DT) as a “fit for purpose digital representation of an observable manufacturing element with synchronization between the element […]
This Case Study describes an approach to combining physical principles with Machine Learning (ML) for modeling and control of complex systems. Our approach was developed as part of a DARPA-funded research project. It was applied to oil reservoir management. While this Case Study provides an overview, technical details may be found in a separate publication […]
Society of Petroleum Engineers (SPE) Virtual Improved Oil Recovery Conference , August 31 − September 4, 2020
Abstract We present a robust control system and methodology for physics-informed artificial intelligence (PAI) used to optimize and improve oil recovery, demonstrated in the Yates Field operated by the Kinder Morgan CO2 company. The system consists of a robust control system (referred to as Dynamic Feedback Loop, or DFL) equipped with novel hydrocarbon sensors that […]
APC Conference XXX 2018
Motivation The last 3 years have seen an increased demand for analog, MEMS and RF chips, which has led to a shortage in both 200mm fab capacity as well as equipment. This has sparked a new interest among equipment makers to refurbish used 200mm tools, develop entirely new tools, or integrate 300mm technology into 200mm […]
2018 COMSOL Training Series
In this talk, Dr. Ebert describes a set of applications where SC used COMSOL Multiphysics® for modeling. These models span the transport of heat, fluids and chemical species, structural mechanics, and electrochemistry. In each case, the models were either validated with experimental data or a simpler version of the model was verified with analytical results.
Presentation at 2017 SSL R&D Workshop, Long Beach, CA, Jan. 31 – Feb. 2, 2017
The research results presented here have demonstrated the feasibility of an innovative temperature control technology for the Metal-Organic Chemical Vapor Deposition (MOCVD) process used in the fabrication of Multi-Quantum Well (MQW) LEDs. The control technology has the strong potential to improve both throughput and performance quality of the manufactured LED. The color of the light […]
Digital Control of Dynamic Systems, 3rd edition, Ellis-Kagle Press, 2006-2022 PDF: This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems. The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude. Both transform-based and state-based classical and modern control methods […]
SC Solutions’ Macro Defect Detection system, SC‐MDD™, is a production‐proven tool that rapidly detects and classifies macro defects for every wafer being processed. SC‐MDD™ includes scanner hardware as well as SC‐WDD™ software which controls the scanning process, performs wafer image processing, and implements wafer die error detection and classification.
This case study of epitaxial deposition of silicon film on a silicon substrate in a horizontal hot-wall reactor reproduces an earlier modeling study by Habuka et al. [1]. The steady-state finite element (FEM) model incorporates fluid flow, heat transfer, dilute species transport, and one-step Arrhenius kinetics at the wafer surface. Additionally, the transport properties of […]
Physics-based MOCVD models are useful in many ways including model-based control, design of next-generation chambers, virtual sensing and process optimization. As a capability demonstration, SC Solutions has developed a finite element (FEM) model of a chamber shown below with design features and geometry obtained from the literature. The model was developed using the popular commercial […]
The modeling team at SC Solutions has developed fluid flow models for a broad range of applications for more than two decades. These models have been developed primarily using the commercial finite element (FEM) modeling tool, COMSOL® Multiphysics, for which SC is a Certified Consultant. SC’s modeling methodology utilizes a hierarchy of models. Depending on […]
Feedback Control of Dynamic Systems, 8th edition, Pearson, 2019, ISBN-13: 9780134685717• ISBN-10: 0134685717
Feedback control fundamentals with context, case studies, and a focus on design, Feedback Control of Dynamic Systems, 8th Edition, covers the material that every engineer needs to know about feedback control—including concepts like stability, tracking, and robustness. Each chapter presents the fundamentals along with comprehensive, worked-out examples, all within a real-world context and with historical […]
Presentation at APC Conference XXIX, Austin, TX, October 9-12, 2017
This presentation describes the development of model-based temperature control of the susceptor of a Metal-Organic Chemical Vapor Deposition (MOCVD) reactor. A generic axisymmetric geometry has been used together with representative process conditions to highlight the issues related to the control of process temperature. Additionally, we describe a method for estimating the minimum number of independent […]
COMSOL Conference 2017, Newton, MA, October 4-6 2017
We have developed a model of a Metal-Organic Chemical Vapor Deposition (MOCVD) reactor using COMSOL Multiphysics, and compared the results by conducting an experimental study. MOCVD is used for the manufacture of Multi-Quantum Well Light Emitting Diodes (MQW LEDs). The process uses a carrier gas flow containing a dilute mixture of metal organic precursors, Tri-Methyl […]
Phys. Rev. A 95, 042325 (2017)
Optimization of the fidelity of control operations is of critical importance in the pursuit of fault-tolerant quantum computation. We apply optimal control techniques to demonstrate that a single drive via the cavity in circuit quantum electrodynamics can implement a high-fidelity two-qubit all-microwave gate that directly entangles the qubits via the mutual qubit-cavity couplings. This is […]
Presentation at APC Conference XXVIII 2016, Mesa, AZ, Oct. 17-20, 2016
Driven by ever-increasing requirements on improved wafer temperature uniformity for smaller features on the wafer, equipment manufacturers are developing heated plates (or chucks) with more and more actuator zones to achieve finer resolution of the actuated heat. From a control standpoint, two principally different plate designs can be distinguished: one that has a temperature sensor […]
Feedback Control of Dynamic Systems, 7th edition, Pearson, 2015, ISBN-10: 0133496597 • ISBN-13: 9780133496598
Feedback Control of Dynamic Systems, 7/e covers the material that every engineer, and most scientists and prospective managers, needs to know about feedback control, including concepts like stability, tracking, and robustness. Each chapter presents the fundamentals along with comprehensive, worked-out examples, all within a real-world context and with historical background information. The authors also provide […]
npj Quantum Information (2015) 1, 15018
Characterizing complex quantum systems is a vital task in quantum information science. Quantum tomography, the standard tool used for this purpose, uses a well-designed measurement record to reconstruct quantum states and processes. It is, however, notoriously inefficient. Recently, the classical signal reconstruction technique known as “compressed sensing” has been ported to quantum information science to […]
Presentation at APC Conference XXVII 2015, Austin, TX, Oct. 12-14, 2015
Driven by ever-increasing requirements on improved wafer temperature uniformity for smaller features on the wafer, equipment manufacturers are developing heated plates (or chucks) with more and more actuator zones to achieve finer resolution of the actuated heat. From a control standpoint, two principally different plate designs can be distinguished: one that has a temperature sensor […]
Presentation at APC Conference XXVI 2014, Ann Arbor, MI, Oct. 1-2, 2014
The manufacturing of Integrated Circuits (ICs) on semiconductor wafers involves hundreds of complex and expensive process steps. Defects can occur during any of several steps such as etch, resist removal, particle contamination, incomplete process, process variations, dislocations, scratches, cracks, etc. Defects range in size from submicron to visually-detectable “macro” defects that may be as large […]
Phys. Rev. B 90, 144504
We apply the method of compressed sensing (CS) quantum process tomography (QPT) to characterize quantum gates based on superconducting Xmon and phase qubits. Using experimental data for a two-qubit controlled-Z gate, we obtain an estimate for the process matrix χ with reasonably high fidelity compared to full QPT, but using a significantly reduced set of […]
Proc. SPIE 9063, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2014, 906311 (9 March 2014) • © 2014 SPI; doi: 10.1117/12.2044617
This study introduces an efficient procedure to estimate the structural response of a suspension bridge in real time based on a limited set of measured data. Unlike conventional techniques, the proposed procedure does not employ mode shapes and frequencies. In this study, the proposed technique is used to estimate the response of a suspension bridge […]
Proc. SPIE Vol. 9063, 906312 (9 March 2014) Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2014 • © 2014 SPIE; doi: 10.1117/12.2044539
This study investigated a number of different damage detection algorithms for structural health monitoring of a typical suspension bridge. The Alfred Zampa Memorial Bridge, a part of the Interstate 80 in California, was selected for this study. The focus was to implement and validate simple damage detection algorithms for structural health monitoring of complex bridges. […]
Phys. Rev. A, 88, 052326 (2013)
Resource tradeoffs can often be established by solving an appropriate robust optimization problem for a variety of scenarios involving constraints on optimization variables and uncertainties. Using an approach based on sequential convex programming, we demonstrate that quantum gate transformations can be made substantially robust against uncertainties while simultaneously using limited resources of control amplitude and […]
Presentation at APC Conference XXV 2013, Ann Arbor, MI, Oct. 14-17, 2013
Detecting the health and proper operation of equipment during manufacturing is an important part of maintaining high yields. This paper describes a model-based approach to detecting changes in equipment during manufacturing. Physics-based mathematical models of the electrostatic chuck (ESC) temperature, RF plasma impedance, and chamber pressure were built for a commercial etch system. Each model […]
Structure and Infrastructure Engineering: Maintenance, Management, Life-Cycle Design and Performance, DOI:10.1080/15732479.2012.757793
This article presents the implementation of a calibration procedure for a finite element (FE) model of a state highway bridge using sensory data measured on the bridge. The objective is to modify the high-fidelity FE model of the bridge so that its dynamic behaviour matches, as closely as possible, that of the bridge under analysis. […]
51st IEEE Conference on Decision and Contro,l December 10-13, 2012.
Multivariable Nyquist eigenloci provide a much richer family of curves as compared to the SISO case. The eigenloci may be computed symbolically in many simple cases. Inspection of the generalized Nyquist eigenloci plot allows the determination of the exact values of the multivariable gain margin (GM), phase margin (PM), and the complex margin (CM). Hence […]
Proceedings of the 2012 COMSOL Conference, Boston, October 3-5, 2012.
This paper describes the development of a COMSOL model of Electro-Chemical-Mechanical Planarization (ECMP) that was validated with experimental data. ECMP is used for processing of semiconductor wafers. We developed a 2D model of flow of phosphoric acid solution (the electrolyte) between two parallel plates that focuses on the physics and electrochemistry in ECMP. The model […]
Presentation at APC Conference XXIV 2012, Ann Arbor, MI, Sept. 10-12, 2012
Many modern thermal processing systems involve temperature control of heated plates. In many systems such as Metal-Organic Chemical Vapor Deposition (MOCVD) and epitaxial deposition (Epi) systems, the plates are often thick carriers or susceptors on which one or more wafers are placed. Typically these plates are heated by radiation from hot filaments and the temperature […]
Proc. SPIE 8347, Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2012, 834727 (April 26, 2012); doi:10.1117/12.916163
A Finite Element (FE) model which can precisely predict the actual dynamic responses of a bridge is necessary for accurate condition assessment and health monitoring purposes. However, most of the bridge FE models initially developed for design purposes may not be able to accurately simulate the current response of the bridges due to various reasons. […]
Presentation at APC Conference XXIII 2011, Ann Arbor, MI, Sept. 12-15, 2011
Many modern thermal processing systems involve temperature control of heated plates. In most Rapid Thermal Processing (RTP) systems, the ‘plate’ is a single wafer that is heated from one or both sides by an array of tungsten halogen lamps. In many other systems such as Metal-Organic Chemical Vapor Deposition (MOCVD) and epitaxial deposition (epi) systems, […]
2011 American Control Conference, San Francisco, CA, USA, June 29 - July 01, 2011, pp. 3116 -3121, 2011.
In this paper we focus on comparing three candidate approaches to the optimal placement of sensors for state estimation-based continuous health monitoring of structures. The first aims to minimize the static estimation error of the structure deflections, using the linear stiffness matrix derived from a finite element model. The second approach aims to maximize the […]
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2010, Ed. Peter J. Shull, Aaron A. Diaz, H. Felix Wu, doi: 10.1117/12.848212, Proc. of SPIE Vol. 7649, San Diego, CA, USA, March 7-11, 2010.
Bridges are an important societal resource used to carry vehicular traffic within a transportation network. As such, the economic impact of the failure of a bridge is high; the recent failure of the I-35W Bridge in Minnesota (2007) serves as a poignant example. Structural health monitoring (SHM) systems can be adopted to detect and quantify […]
Phys. Rev. Lett. 106, 100401
The resources required to characterise the dynamics of engineered quantum systems-such as quantum computers and quantum sensors-grow exponentially with system size. Here we adapt techniques from compressive sensing to exponentially reduce the experimental configurations required for quantum process tomography. Our method is applicable to dynamical processes that are known to be nearly-sparse in a certain […]
Phys. Rev. A 84, 012107
We develop an efficient and robust approach to Hamiltonian identification for multipartite quantum systems based on the method of compressed sensing. This work demonstrates that with only O(s log(d)) experimental configurations, consisting of random local preparations and measurements, one can estimate the Hamiltonian of a d-dimensional system, provided that the Hamiltonian is nearly s-sparse in […]
Proceedings of the SEM Annual Conference, Indianapolis, IN, June 7-10, 2010.
In this paper, we present results on estimating material model parameters from inverse analysis of full-field deformation data that was obtained with a prototype of a novel integrated tool consisting of a digital image correlation system and software for data analysis and parameter estimation. Such a tool is needed for characterizing the properties of new […]
Nondestructive Characterization for Composite Materials, Aerospace Engineering, Civil Infrastructure, and Homeland Security 2010, Ed. Peter J. Shull, Aaron A. Diaz, H. Felix Wu, doi: 10.1117/12.847704, Proc. of SPIE Vol. 7649, San Diego, CA, USA, March 7-11, 2010.
In this paper we focus on the optimal placement of sensors for state estimation-based continuous health monitoring of structures using three approaches. The first aims to minimize the static estimation error of the structure deflections, using the linear stiffness matrix derived from a finite element model. The second approach aims to maximize the observability of […]
New Journal of Physics, Volume 12, January 2010
The problem of quantifying the difference between evolutions of an open quantum system (in particular, between the actual evolution of an open system and the ideal target operation on the corresponding closed system) is important in quantum control, especially in control of quantum information processing. Motivated by this problem, we develop a measure for evaluating […]
New Journal of Physics, Volume 11, November 2009
We propose and evaluate experimentally an approach to quantum process tomography that completely removes the scaling problem plaguing the standard approach. The key to this simplification is the incorporation of prior knowledge of the class of physical interactions involved in generating the dynamics, which reduces the problem to one of parameter estimation. This allows part […]
arXiv:0812.4323v1 [quant-ph], 12/23/2008
For an initially well designed but imperfect quantum information system, the process matrix is almost sparse in an appropriate basis. Existing theory and associated computational methods (L1-norm minimization) for reconstructing sparse signals establish conditions under which the sparse signal can be perfectly reconstructed from a very limited number of measurements (resources). Although a direct extension […]
Proceedings of the Symposium to honor W.~Wolovich, the 47th IEEE Conference on Decision and Control, Cancun, Mexico, December 9-11, 2008.
A semiconductor wafer undergoes a wide range of processes before it is transformed from a bare silicon wafer to one populated with millions of transistor circuits. Such processes include Physical or Chemical Vapor Deposition, (PVD, CVD), Chemical-Mechanical Planarization (CMP), Plasma Etch, Rapid Thermal Processing (RTP), and photolithography. As feature sizes keep shrinking, process control plays […]
arXiv:0810.2524v1 [quant-ph], 10/14/2008.
We develop a theory for finding quantum error correction (QEC) procedures which are optimized for given noise channels. Our theory accounts for uncertainties in the noise channel, against which our QEC procedures are robust. We demonstrate via numerical examples that our optimized QEC procedures always achieve a higher channel fidelity than the standard error correction […]
AEC/APC Symposium, Salt Lake City, Utah, 2008.
arXiv:0803.4284v1 [quant-ph], 3/29/2008
Maximizing the precision in estimating parameters in a quantum system subject to instrumentation constraints is cast as a convex optimization problem. We account for prior knowledge about the parameter range by developing a worst-case and average case objective for optimizing the precision. Focusing on the single parameter case, we show that the optimization problems are […]
arXiv:quant-ph/0703274v2, Phys. Rev. Lett. 100, 020502 (2008)
We present a semidefinite program optimization approach to quantum error correction that yields codes and recovery procedures that are robust against significant variations in the noise channel. Our approach allows us to optimize the encoding, recovery, or both, and is amenable to approximations that significantly improve computational cost while retaining fidelity. We illustrate our theory […]
NanoTech 2007: NSTI Nanotechnology Conference and Trade Show, Santa Clara, May 20-24, 2007.
An all-digital cantilever controller for magnetic resonance force microscopy (MRFM) was developed through a close collaboration between SC Solutions, Cornell University, and the U.S. Army Research Laboratory. The advantage of an all-digital controller is its absence of thermal drift, as well as its great tuning flexibility. This versatile controller is comprised of a Field Programmable […]
arXiv:quant-ph/0702147v2, J. Phys. B: At. Mol. Opt. Phys. 40, S103-S125 (2007)
Methods of optimal control are applied to a model system of interacting two-level particles (e.g., spin-half atomic nuclei or electrons or two-level atoms) to produce high-fidelity quantum gates while simultaneously negating the detrimental effect of decoherence. One set of particles functions as the quantum information processor, whose evolution is controlled by a time-dependent external field. […]
arXiv:quant-ph/0611189v2, 2/2/2007
This work studies the feasibility of optimal control of high-fidelity quantum gates in a model of interacting two-level particles. One set of particles serves as the quantum information processor, whose evolution is controlled by a time-dependent external field. The other particles are not directly controlled and serve as an effective environment, coupling to which is […]
arXiv:0712.2935v1 [quant-ph], Special issue of the Journal of Modern Optics: 37th Winter Colloquium on the Physics of Quantum Electronics, 2-6 January 2007.
This work studies the feasibility of optimal control of high-fidelity quantum gates in a model of interacting two-level particles. One particle (the qubit) serves as the quantum information processor, whose evolution is controlled by a time-dependent external field. The other particles are not directly controlled and serve as an effective environment, coupling to which is […]
arXiv:quant-ph/0606078v1, 6/9/2006.
We show that the problem of designing a quantum information error correcting procedure can be cast as a bi-convex optimization problem, iterating between encoding and recovery, each being a semidefinite program. For a given encoding operator the problem is convex in the recovery operator. For a given method of recovery, the problem is convex in […]
arXiv:quant-ph/0606064v1, 6/7/2006.
A distance measure is presented between two unitary propagators of quantum systems of differing dimensions along with a corresponding method of computation. A typical application is to compare the propagator of the actual (real) process with the propagator of the desired (ideal) process; the former being of a higher dimension then the latter. The proposed […]
arXiv:quant-ph/0412059v3, New J. Phys. 8, 35 (2006).
We present a formalism for encoding the logical basis of a qubit into subspaces of multiple physical levels. The need for this multilevel encoding arises naturally in situations where the speed of quantum operations exceeds the limits imposed by the addressability of individual energy levels of the qubit physical system. A basic feature of the […]
44th IEEE Conference on Decision and Control 2005 and 2005 European Control Conference CDC-ECC '05., page(s): 7366 - 7371, 12-15 Dec. 2005.
We describe a control-oriented model reduction process from partial differential equation (PDE) descriptions of aerodynamic flow systems, and the design of low-order feedback controllers using these procedures. An effective approach for flow model reduction for active control using balanced truncation approaches was developed. The techniques were applied to a flow control problem representative of aerospace […]
arXiv:quant-ph/0411093v1, 11/12/2004.
A number of problems in quantum state and system identification are addressed. Specifically, it is shown that the maximum likelihood estimation (MLE) approach, already known to apply to quantum state tomography, is also applicable to quantum process tomography (estimating the Kraus operator sum representation (OSR)), Hamiltonian parameter estimation, and the related problems of state and […]
Proceedings of the 2004 American Control Conference, Volume 5, 30 June-2 July 2004, pp. 3922-3929, 2004.
The research described in this tutorial paper involves an effort for physical modeling and model-based sensing and control of CMP systems. A dynamic model of a rotational CMP process is developed, as well as simulation software. This dynamic model is used for feedback control design based on in-situ thickness measurements, as well as run-to-run control […]
Proceedings of the 2004 American Control Conference, 30 June -2 July 2004, page(s): 3902 - 3909 vol.5, 2004.
A semiconductor wafer undergoes a wide range of processes before it is transformed from a bare silicon wafer to one populated with millions of transistor circuits. Such processes include physical or chemical vapor deposition, (PVD, CVD), chemical-mechanical planarization (CMP), plasma etch, rapid thermal processing (RTP), and photolithography. As feature sizes keep shrinking, process control plays […]
Proceedings of the 2004 American Control Conference, 30 June-2 July 2004, Volume: 5, pp. 3930-3941, 2004.
Radio frequency (RF) diode sputtering is widely used for depositing Giant Magneto-Resistive (GMR) thin films for multilayers, spin valves, and spin-dependent tunneling (SDT) devices used in data storage, computer memory, etc. However, the thin films thus produced often show unacceptably high variation in GMR properties from wafer to wafer. This paper describes a modeling and […]
Proceedings of the 2004 American Control Conference, page(s): 3910 - 3921 vol.5, 2004.
This work describes the application of model-based control system design techniques to rapid thermal processing (RTP). The work considers all aspects of the distributed temperature control problem from physics-based modeling to implementation of the real-time embedded controller. With its exceptionally stringent performance requirements (low non-uniformity of wafer temperature, high temperature ramp rates), RTP temperature control […]
arXiv:quant-ph/0403150v1, 3/21/2004.
The problem addressed is to design a detector which is maximally sensitive to specific quantum states. Here we concentrate on quantum state detection using the worst-case a posteriori probability of detection as the design criterion. This objective is equivalent to asking the question: if the detector declares that a specific state is present, what is […]
IEEE Transactions on Control Systems Technology, Volume 11, Issue 5, Page(s):668 - 683, Sept. 2003.
This paper investigates the application of model-based control design techniques to distributed temperature control systems. Multivariable controllers are an essential part of modern-day rapid thermal processing (RTP) systems. We consider all aspects of the control problem beginning with a physics-based model and concluding with implementation of a real-time embedded controller. The thermal system used as […]
Chapter in "Model Identification and Adaptive Control: From Windsurfing to Telecommunications ", G. Goodwin (ed.), Springer-Verlag, 2001.
Part of a collection of contributions written in honor of Professor Brian Anderson's 60th birthday.
Proceedings of the 39th IEEE Conference on Decision and Control, Sydney, Australia, December, 2000.
Application notes, 2000.
A reactor-scale model incorporating the principal physical processes involved in RF diode sputtering has been developed and then integrated into a detailed steady-state input-output model of the growth of copper films. The model links critical aspects of the process (plasma power and pressure), the geometry of the chamber, and the materials (working gas, target materials) […]
Proceedings of the ASME Dynamic Systems and Control Divison-2000, pp. 153-161, November 2000.
S. C. Application Notes, 2000.
Radio frequency (RF) diode sputtering deposition is a widely used process for depositing GMR thin films for multilayers, spin valves, spin-dependent tunneling (SDT) devices, etc. However, the thin films thus produced often show significant variation in GMR properties from wafer to wafer. A multiscale model based on the primary physical phenomena – gas flow, plasma discharge, […]
Proceedings of the 38th Conference on Decision & Control, Phoenix, AZ, December 1999, pp. 4204-4208.
Application Notes, SC Solutions, Inc., 1999.
This whitepaper details a systematic methodology for concurrent development of reactor-scale physical model and model-based process control development for metal-organic chemical vapor deposition (MOCVD). The example used for illustrating the approach is the deposition of yttrium-barium-copper oxide (YBa2Cu3O7-x or YBCO) thin films with high temperature superconducting (HTS) properties. Information about the gas-phase chemical mechanisms, obtained from experimental […]
Journal of Vacuum Science & Technology A, Vol. 17, No. 4, pp. 1926-1933, 1999.
Proceedings of the Seventh International Conference on Advanced Thermal Processing of Semiconductors, RTP '99, Colorado Springs, September 1999.
Application Notes, 1999.
In this white paper, we describe the numerical simulation of CVD process for epitaxial growth of silicon using trichlorosilane (SiHCl3). This study uses the one-step, finite-rate chemistry for the 2-D reactor geometry from the literature, and successfully reproduces the published results. A commercial software package, CFD-ACEe, popular in the semiconductor industry, was used for our […]
13th ASCE Engineering Mechanics Division Conference held in Baltimore, June 13-16, 1999.
In this paper the application of control theory to structural engineering has been presented from a structural engineering perspective. The objective of this paper is to summarize key steps that are required to design an active control system for a structure. Total acceleration feedback with H2/LQG controller is used in this paper. The structural control […]
Presented at the Third Symposium of Process Control, Diagnostics, and Modeling in Semiconductor Manufacturing, 195th Meeting of the Electrochemical Society, Seattle, May 2-6, 1999.
A 2D model of MOCVD reactor has been developed for deposition of YBCO thin films. System characterization showed the need for control of growth rate, deposition uniformity, and oxide stoichiometry at the surface. A run-to-run control architecture was developed, and is being implemented.
Journal of the American Ceramic Society, Vol. 82, No. 3, pp. 513-520, 1999.
Gelcasting is a promising new technology for manufacturing advanced structural ceramic components. The process involves drying of the ‘green’ gelcast part before densiï¬cation. The physical mechanisms controlling this relatively long drying process are not well understood. In this study, several controlled experiments were performed to elucidate the key mechanisms. A one-dimensional drying model was formulated […]
Automatica, Vol. 34, No. 11, pp. 1449-1452, 1998.
Proceedings of the 37th IEEE Conference on Decision and Control, pp. 695-700, Tampa, Florida, December, 1998.
Run-to-run control using static linear models is examined. Conditions are presented for stability, (statistical) performance, and robustness using standard control theory. A simulation example shows the usefulness of the method applied to a rapid thermal oxidation (RTO) process.
Proceedings of the Sixth International Conference on Advanced Thermal Processing of Semiconductors, RTP '98, Kyoto, Japan, September 9-11, 1998.
Proceedings of the 1997 IEEE International Conference on Control Applications, Hartford, CT. October 5-7, 1997.
Gelcasting is a new method for manufacturing advanced structural ceramics for use, for example, in the aerospace industry. The process involves a drying stage, where moisture, which constitutes approximately a quarter of the mass of the part, is removed in a commercial dryer. The control system design for the gelcast ceramic drying process is complicated […]
Proceedings of the Fifth International Conference on Advanced Thermal Processing of Semiconductors, RTP '97, New Orleans, LA, September 3-5, 1997.
General finite element models of single wafer systems that describe both the dynamics of the solids as well as the gases are usually unsuited for quick design iterations, because of the computational complexity. In this paper a computationally more efficient alternative is proposed. The solids can be modeled efficiently and sufficiently accurate using a finite volume approach. The gases are […]
American Control Conference, June 26-28, 1991
Systems Control Technology, Inc. is participating in the Air Force program entitled “Robust Control Law Development for Modern Aerospace Vehicles” (MAVRIC) as a subcontractor to Northrop Aircraft Division. The goal of this program is to apply state-of-the-art robust control law design methodologies to high-performance aircraft with significant modelling errors (uncertainties). The uncertainties which are being […]
24th IEEE Conference on Decision and Control, December 1985
A decentralized, robust, multivariable controls method is described for the functional integration of subsystems in large-scale systems characterized by dynamic coupling among subsystem elements. In an integrated environment, a decentralized control structure reduces the complexity of the control by distributing the control authority to local controllers. The method relies upon generation of a set of […]
Journal of Guidance, Control, and Dynamics, Vol. 6, No. 2 (1983), pp. 104-111.
A well-designed feedback control system exhibits the properties of external disturbance attenuation and performance robustness with respect to plant uncertainty. The plant uncertainties of flexible spacecraft include unmodeled dynamics and parameter uncertainties. Singular value robustness measures are used to compare performance and stability robustness properties of different control design techniques in the presence of residual […]