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Linear and affine (Ax+B) models are commonly used to model equipment throughput in semiconductor wafer fabricator simulations. We endeavor to assess the quality of such models for the prohibitively expensive clustered photolithography scanner. The simulations demonstrate that such models are of varying quality. They can exhibit significant deviation from the system behavior when the simulation parameters,...
As in many other parts of the world, overcrowding in Taiwan's hospital Emergency Departments (ED) is an increasingly scrutinized area. EDs in Taiwan hospitals must implement efficient systems that minimize costs while also providing satisfactory levels of care. The primary goal of this investigation is to develop and deploy a mixed method incorporating Discrete Event Simulation (DES) and Data Envelopment...
Multi-product production systems with sequence-dependent setup times are typical in manufacturing of semiconductor chips and other electronic products. In such systems, the scheduling policies to coordinate the production of multiple product types play an important role. In this paper, we study a multi-product manufacturing system with finite buffers, sequence-dependent setup times and various scheduling...
The anticipated transition to 450 mm diameter wafers provides the semiconductor manufacturing industry an opportunity to consider new equipment designs that address issues associated with small lot sizes and high mix production. One candidate design is the linear cluster tool. Compared to traditional circular cluster tools, linear cluster tools have advantages such as high flexibility and greater...
In this paper, we analyze the impact of control plan design of defectivity inspections for tool risk management. Defectivity inspections are performed on products and can reveal the yield loss produced by contaminations or structural flaws. The risk considered in this paper concerns the exposure level of wafers on a tool between two defectivity controls. Our goal is to analyze how control plans can...
The application of discrete event simulation in the process industries is commonly used for the analysis of reliability and maintenance improvements. However there have been increasing applications that go beyond this traditional area of application to include evaluations for chemical plant expansions, capital investment options, cycle time reduction and safety, in presence of failure prone components...
Abstraction level of complex simulation models such as large manufacturing systems is always a critical factor in simulation projects. It not only helps define boundaries of a simulation model but also defines the complexity and resource requirements for the model. Many a times a simple looking model grows into a complex model because of incorrect choices in abstraction level. Developing the model...
Several factors and restrictions affect paint shop design. Due to the high level of complexity of paint shops, classical mathematical optimization methods are generally not applicable. Simulation-based optimization has been often used in recent years as an alternative to classical mathematical optimization methods. This paper presents an optimization function for paint shop design, its constraints,...
Automated material handling systems (AMHS) using conveyors have been recently proposed as a technology option for next generation wafer fabrication facilities. This technology seems to provide an increasing capacity for moving and storing wafers in a continuous flow transport environment. The goal of this research is to design and test conveyor-based AMHS configurations, which include turntables and...
In this paper we explore a lot release policy for wafer fabs that is based on the WIP threshold of the bottleneck station. Our results show that this policy is effective in cycle time improvement while keeping the same level of throughput compared with a case where no policy is applied. The application of this policy is practical and needs less considerations compared to policies that aim at keeping...
Most cluster tool scheduling studies assume identical access times between chambers, or do not discuss impact of the access times although the optimal scheduling rule and the cycle time can depend on the access times or physical configuration of parallel chambers. We examine cyclic scheduling problems for cluster tools that have non-identical access times. We first develop Petri net models of tool...
Semiconductor manufacturing is a capital-intensive industry. How to utilize billions of dollars of equipment as efficiently as possible is a critical factor for a semiconductor manufacturer to succeed in stiff competition. Unlike operations management techniques, like planning and scheduling, which are proven to improve tool performance by controlling WIP (work-in-process) movement, tool science techniques...
In this paper, we present an approach to automatically create an analytical process time model for cluster tools using real-world data. The proposed model combines advantages of simple throughput models and discrete event simulation models. We consider the effect of small lot size and the slow down effect occurring when simultaneously processed lots interfere with each other. Especially the use of...
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