Online Simulation in Semiconductor Manufacturing

In semiconductor manufacturing discrete event simulation systems are quite established to support multiple planning decisions. During the recent years, the productivity is increasing by using simulation methods. The motivation for this thesis is to use online simulation not only for planning decisions, but also for a wide range of operational decisions. Therefore an integrated online simulation system for short term forecasting has been developed. The production environment is a mature high mix logic wafer fab. It has been selected because of its vast potential for performance improvement. In this thesis several aspects of online simulation will be addressed: The first aspect is the implementation of an online simulation system in semiconductor manufacturing. The general problem is to achieve a high speed, a high level of detail, and a high forecast accuracy. To resolve these problems, an online simulation system has been created. The simulation model has a high level of detail. It is created automatically from underling fab data. To create such a simulation model from fab data, additional problems related to the underlying data arise. The major parts are the data access, the data integration, and the data quality. These problems have been solved by using an integrated data model with several data extraction, data transformation, and data cleaning steps. The second aspect is related to the accuracy of online simulation. The overall problem is to increase the forecast horizon, increase the level of detail of the forecast and reduce the forecast error. To provide useful forecast results, the simulation model contains a high level of modeling details and a proper initialization. The influences on the forecast quality will be analyzed. The results show that the simulation forecast accuracy achieves good quality to predict future fab performance. The last aspect is to find ways to use simulation forecast results to improve the fab performance. Numerous applications have been identified. For each application a description is available. It contains the requirements of such a forecast, the decision variables, and background information. An application example shows, where a performance problem exists and how online simulation is able to resolve it. To further enhance the real time capability of online simulation, a major part is to investigate new ways to connect the simulation model with the wafer fab. For fab driven simulation, the simulation model and the real wafer fab run concurrently. The wafer fab provides several events to update the simulation during runtime. So the model is always synchronized with the real fab. It becomes possible to start a simulation run in real time. There is no further delay for data extraction, data transformation and model creation. A prototype for a single work center has been implemented to show the feasibility

Automatic Electronic Control of the Level of LPG in air in a Confined Space

Documentation of the automatic electronic control of the level of LPG in air in a confined space can be viewed in this project. Humans are increasingly becoming dependent on petrochemical products for their daily life. Ignition of these combustible products can have catastrophic effect especially in a confined space where there exist limited amount of air. Therefore, a sensor is needed to monitor the level of gases in homes and also in industry to avoid all possibilities of the accidents. The aim of this project is to design an automatic electronic control of the level of flammable gases in a closed chamber as one of the solution in curbing the concentration of these gasses from increasing in air and reaching its lower explosive limit (LEL). Literature review was done in order to select the suitable sensor and the appropriate circuit. Some lab work was also conducted to verifY all the findings and simulate the circuit designed. After simulation, the circuit was designed and tested on breadboard. Graphs of voltage changes versus time and when exposed to gas was plotted. From detailed analysis using the spreadsheet provided, it was demonstrated that the sensor is very sensitive and its response time is less than a minutes. The circuit is demonstrated to be working once the sensor is to be working once the sensor is exposed to the gas by actuating a venting fan. A prototype sensor circuit is finally designed and tested

Information tracking and sharing in organic photovoltaic panel manufacturing

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 76-77).The MIT MEng team of four worked with Konarka Technologies, a world leading organic solar panel manufacturer, on production tracking and analysis as well as various operational improvement projects. MIT's collaborative improvement projects at Konarka's manufacturing facility were focused on information system and operations in the finishing processes after solar panels have been coated. This thesis report, however, focuses primarily on information tracking and sharing in Konarka's manufacturing facility, specifically including the barcode tracking system for production tracking, operator interfaces for the system, production tracking (Kanban card) board, and Kaizen continuous improvement board. A barcode tracking system for solar panel and associated user interfaces portion was developed to increase process and inventory accountability. However, because of the intricate SQL database, it may still be difficult for any operator to access this information in the recent future. Hence, physical representative information boards were developed to alleviate this communication complexity. One Kanban (card style) board was implemented to keep track of production information, and another Kaizen (continuous improvement) board was established to keep track of all the continuous activities on the shop floor. Based on various reviews and discussions, these improvement projects served as useful tools for the company's production ramp-up development. Keywords: barcode, tracking system, production tracking, lean, Kanban, Kanban board, Kaizen, Kaizen board, information board, card, card board.by Ming Gong.M.Eng

Optimization of in-line semiconductor measurement rates : balancing cost and risk in a high mix, low volume environment

Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2004.Includes bibliographical references (p. 99-101).Due to a number of market development over the last decade, semiconductor manufacturing companies, including Intel Corporation, have added significant numbers of primarily high growth rate, high-mix, low-volume (HMLV) products to their portfolios. The rapid transition from high-volume manufacturing (HVM) to HMLV manufacturing has caused significant problems. Foremost, the needs of many HMLV customers are different from HVM customers and require different operational tradeoffs. Moreover, many of the HVM focused metrics, tools, systems and processes have proven ill-suited for managing the added complexities and more varied needs of HMLV customers. This thesis examines many of the problems caused by introducing HMLV products into an HVM wafer fabrication facility (commonly referred to as a fab), and explores potential solutions such as improved cultural and organizational alignment; capacity management and setup elimination; and scheduling and work-in-process management to name a few. Although the discussion focuses on semiconductor operations, the concepts easily generalize to other companies struggling with achieving operational excellence (OpX) in an HMLV environment. In addition to exploring the macroscopic HMLV issues, we also feature an in-depth analysis of one aspect of achieving OpX in the HMLV environment: the optimization of in-line metrology skip rates. Based on a review of the current methods, a new approach is suggested based on a Bayesian economic skip-lot model we call MOST/2. In general, MOST/2 suggests that significant cost savings can be realized with only modest increases in the material at risk per excursion if measurement rates are further reduced. Compared with the other methods analyzed, the data indicates that MOST/2(cont.) provides superior cost/risk balanced results. For the 27 operations analyzed, results include annual costs savings of over $95,000, cycle time savings of over 5.3 hours per lot, operator savings of over 4.2 people per year and metrology capacity utilization rate reductions of over 65%. Finally, a brief organizational study was conducted to identify political, cultural and strategic design changes that would bolster long-term operational excellence (OpX) in the HMLV environment. Suggested changes include better identification of customer needs, improved communication and linking between groups, modification and alignment of factory and performance metrics and the creation of a stand-alone HMLV organization.by Christopher R. Pandolfo.S.M.M.B.A

New approaches to optimize freeze-drying of monoclonal antibodies

Over the last years, serious interest in emerging next-generation freeze-drying technologies raised. One promising technology that stands out due to its proven benefits in food technology is microwave-assisted freeze-drying (MFD). As briefly outlined in section I.3.2, MFD has the potential to overcome drawbacks like long drying-times due to its volumetric heating of the entire sample. However, little is known of its feasibility for pharmaceutical applications, particularly in the field of sensitive biologicals. For this reason, the first part of this thesis, Chapter II and Chapter III, is dealing with the investigation of vial-based microwave-assisted freeze-drying concerning the applicability to standard lyophilization formulations and effects on protein stability. In Chapter II, the applicability and feasibility of this technology to different monoclonal antibody formulations and the influence on the resulting product properties are subject to investigation. Moreover, the potential for drying time savings is examined. The product quality of four different pharmaceutically relevant monoclonal antibody formulations over storage and the influence of the microwave generator on batch homogeneity are studied in Chapter III. The second part of this work, Chapter IV – Chapter VI, is dedicated to detailed investigations on open questions in controlled ice nucleation (CN) in the field of freeze-drying of biologicals. Although there have been multiple publications, reports, and case studies about CN over the last two decades, experts in the freeze-drying community are still lacking essential information on aspects of comparability of different controlled ice nucleation techniques, general good practice of process design, and how to monitor the nucleation success of a whole batch non-destructively. In Chapter IV, a case study of three relevant model formulations is presented which aims to investigate if mechanistically different controlled ice nucleation techniques in freeze-drying are comparable to each other concerning drying process performance and product quality attributes. A study analyzing factors that affect the success of CN and questions of process design are studied and discussed in Chapter V. In Chapter VI a new technological solution for control of the nucleation success using a camera-based approach is presented in a proof of concept study. Chapter VII summarizes and concludes the results of the present thesis and gives an outlook

New approaches to optimize freeze-drying of monoclonal antibodies

Over the last years, serious interest in emerging next-generation freeze-drying technologies raised. One promising technology that stands out due to its proven benefits in food technology is microwave-assisted freeze-drying (MFD). As briefly outlined in section I.3.2, MFD has the potential to overcome drawbacks like long drying-times due to its volumetric heating of the entire sample. However, little is known of its feasibility for pharmaceutical applications, particularly in the field of sensitive biologicals. For this reason, the first part of this thesis, Chapter II and Chapter III, is dealing with the investigation of vial-based microwave-assisted freeze-drying concerning the applicability to standard lyophilization formulations and effects on protein stability. In Chapter II, the applicability and feasibility of this technology to different monoclonal antibody formulations and the influence on the resulting product properties are subject to investigation. Moreover, the potential for drying time savings is examined. The product quality of four different pharmaceutically relevant monoclonal antibody formulations over storage and the influence of the microwave generator on batch homogeneity are studied in Chapter III. The second part of this work, Chapter IV – Chapter VI, is dedicated to detailed investigations on open questions in controlled ice nucleation (CN) in the field of freeze-drying of biologicals. Although there have been multiple publications, reports, and case studies about CN over the last two decades, experts in the freeze-drying community are still lacking essential information on aspects of comparability of different controlled ice nucleation techniques, general good practice of process design, and how to monitor the nucleation success of a whole batch non-destructively. In Chapter IV, a case study of three relevant model formulations is presented which aims to investigate if mechanistically different controlled ice nucleation techniques in freeze-drying are comparable to each other concerning drying process performance and product quality attributes. A study analyzing factors that affect the success of CN and questions of process design are studied and discussed in Chapter V. In Chapter VI a new technological solution for control of the nucleation success using a camera-based approach is presented in a proof of concept study. Chapter VII summarizes and concludes the results of the present thesis and gives an outlook

Building operational excellence in a multi-node supply chain

Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2005.Includes bibliographical references (p. 92-93).This thesis shows how a combination of macro-economic, business, and organizational factors can lead a well-run company to adopt a "launch-and-expedite" behavior with detrimental effects on operational efficiency. It also demonstrates how it is possible, for an organization that finds itself in such a state, to apply basic operations principles and a data driven approach to systematically get out of the "launch-and-expedite" mode. The thesis presents a method to characterize a real, functioning supply chain in the context of changing conditions and in the absence of perfect data. It shows the analysis, recommendations, and results from a particular supply chain case study at Agilent Technologies, Inc. The project first analyzes and maps the current supply chain to characterize demand and supply variability. A selected menu of operational building blocks is then recommended to improve overall supply chain performance by reducing the internal bullwhip effect and improving on-time delivery. The recommendations are implemented in a successful pilot study and key operational metrics are recorded such as supply chain inventory, on-time delivery, variability of lead-time, and number of expedite/schedule change requests.(cont.) The particular organizational context of the project and its affect is also considered. Although this thesis provides a case study of the Colorado Springs Technical Center operations and supply chain, results and lessons learned are applicable to other component suppliers or component buyers within multi-node supply chains, particularly those in the capital equipment business.by Mark K. Sahney.S.M.M.B.A

Process Improvement and Lift Design for the Installation of a Metrology Machine Assembly

The objective is to work with Onto Innovations, a leading provider of semiconductor metrology and manufacturing solutions, to develop a system that safely installs a 250lb optics plate into the Atlas III: one of their metrology machines. Based in Milpitas, CA, Onto Innovations utilizes a variety of operations to create different products and assembles each product on site. The 250lb optics plates are WIP that are transferred between fixtures and the Atlas III using a combination of lifts and human workers. The WIP have long lead times, high tolerances, and large costs associated with their manufacturing process. Onto Innovations identified a specific transfer in the WIP where they would like this team to find a safer and more efficient solution for the product and workers. Onto Innovations currently have rough solutions mocked up, but no significant progress has been made due to a lack of manpower. The Director of Operations Engineering, Jon, would like the team to re-address the problem and design a new process, lifting tool, and/or fixture to safely conduct the operation. A preliminary budget of $5,000 has been set for the project, and Onto Innovations expects a final product by the end of December 2019 that will work reliably, safely, and efficiently. The team conducted a preliminary analysis and developed three distinct solutions. The primary solution is designing and manufacturing a small, portable lift that will be temporarily installed inside the Atlas III. The secondary solution is to modify the current lift Onto Innovations uses by changing the leg design and weight distribution. The tertiary solution is to create an SOP for the current installation process, as this will entail no product design or product modification. Further development of the preliminary analysis concluded in the team moving forward with the primary solution. Using a mechanical design approach and extensive ergonomic consideration, the team developed a lift that bolts up into the Atlas III frame and meets all Onto Innovations’ requirements. The design process entailed several revisions to the lift, including the redesign of major assemblies. However, once a detailed prototype design had been developed, the team transitioned into manufacturing. Three weeks of machining and welding lead to the creation of the first prototype, which was then tested for fitment and maneuverability. The team delivered the underhung lift to Onto Innovations, and after a run-through of the process and a test fit, the team realized the positive and negative attributes of the design. Some aspects, such as the trolley that rides underneath the i-beam, need some additional design considerations. However, Onto Innovations was satisfied with the initial prototype and look forward to building 3 upon the team’s work to develop a product that will address the issues found in testing. In addition to the prototype, an SOP and full CAD model were delivered to Onto Innovations so that the design can be modified, remanufactured, and the process can be solidified

High Throughput Manufacturing of Thin-Film CdTe Photovoltaic Materials; Final Subcontract Report, 16 November 1993-31 December 1998

This report describes work performed by Solar Cells, Inc. (SCI), during this Photovoltaic Manufacturing Technology (PVMaT) subcontract. Cadmium telluride (CdTe) is recognized as one of the leading materials for low-cost photovoltaic modules. SCI has developed this technology and is preparing to scale its pilot production capabilities to a multi-megawatt level. This four-phase PVMaT subcontract supports these efforts. The work was related to product definition, process definition, equipment engineering, and support programs development. In the area of product definition and demonstration, two products were specified and demonstrated-a grid-connected, frameless, high-voltage product that incorporates a pigtail potting design and a remote low-voltage product that may be framed and may incorporate a junction box. SCI produced a 60.3-W thin-film CdTe module with total-area efficiency of 8.4%; SCI also improved module pass rate on the interim qualification test protocol from less than 20% to 100% as a result of work related to the subcontract. In the manufacturing process definition area, the multi-megawatt manufacturing process was defined, several of the key processes were demonstrated, and the process was refined and proven on a 100-kW pilot line that now operates as a 250-kW line. In the area of multi-megawatt manufacturing-line conceptual design review, SCI completed a conceptual layout of the multi-megawatt lines. The layout models the manufacturing line and predicts manufacturing costs. SCI projected an optimized capacity, two-shift/day operation of greater than 25 MW at a manufacturing cost of below $1.00/W