Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-10-16
2003-12-30
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S099000, C700S123000
Reexamination Certificate
active
06671570
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the present invention relates to systems and methods for monitoring and assessing the performance and operation of fabrication facilities, such as semiconductor fabrication facilities.
2. Brief Description of Related Developments
The manufacture of microelectronic circuits and/or components on semiconductor wafers can be a complex and involved process, requiring numerous tools and machines operating in a production sequence according to a specified set of instructions (e.g., a “recipe”). Examples of fabrication processes typically performed in the manufacture of a semiconductor wafer include etching, deposition, diffusion, and cleaning.
Large semiconductor fabrication facilities can have dozens or even hundreds of tools, each of which is called upon periodically to perform part of a process as dictated by the selected recipe(s). Some fabrication tools are used for processing semiconductor wafers, while others, known as metrology tools, are generally used for measuring the output of a processing tool. Fabrication tools are often employed in an assembly-line fashion, with each applicable tool having a role in the step-by-step fabrication of a semiconductor wafer. However, due to the nature of the step-by-step manufacturing processes, at least some tools will be idle at any given time, waiting for the output of an upstream tool. Fabrication tools can also be idle for other reasons, such as when needing maintenance, repair or re-programming, or re-configuration with respect to other tools in the plant. The amount of time fabrication tools are idle bears a correlation, directly or indirectly, to the overall efficiency of a semiconductor fabrication facility, and hence a correlation to the profitability of the facility. A challenge for each fabrication facility is thus to reduce idle time of fabrication tools to the maximum extent possible, therefore maximizing production time, yield and profitability.
Moreover, many processing tools and metrology tools are quite expensive, and the collective array of tools brought together at a semiconductor fabrication facility represent a substantial investment. To the extent tools are idle, the investment in these tools is wasted. The floor space at semiconductor fabrication facilities is also enormously expensive, due to extreme requirements of cleanliness, among other reasons, and so even inexpensive tools which are idle can be costly in terms of wasted floor space that is being underutilized. Furthermore, large semiconductor fabrication facilities often will have many duplicate tools for performing processes in parallel. If facility engineers can determine that certain duplicate tools are idle for long periods, then some of the duplicate tools can potentially be eliminated, saving both the cost of the tools and the floor space that they take up. Alternatively, if all of a certain type of tool is operating at maximum efficiency yet still are the cause of a bottleneck in the manufacturing process, production engineers may determine that more tools need to be purchased. Therefore, a tremendous need exists to identify which fabrication tools are active and which idle, and for what reasons. For example, if a fabrication tool was idle for a long period because the upstream process step takes a long time, a production engineer may come to a different conclusion about how to adjust facility resources than if the idle period was due to the fact that the upstream fabrication tool was broken and needed to be repaired. Thus, the reason for tool idleness can be important information for engineers controlling semiconductor manufacturing processes.
To assist production engineers in assessing semiconductor manufacturing efficiency, a variety of informational reporting standards have been promulgated. One of the earliest such standards is known as the E10-0699 Standard for Definition and Measurement of Equipment Reliability, Availability and Maintainability (RAM) (hereinafter the “E10 Standard”), hereby incorporated by reference as if set forth fully herein. This standard, originally put forward around 1986 by Semiconductor Equipment and Materials International (SEMI), defines six basic equipment states into which all equipment conditions and periods of time (either productive or idle time) must fall. Total time for each tool is divided into Operations Time and Non-Scheduled Time. Operations Time is divided into five different categories (Unscheduled Downtime, Scheduled Downtime, Engineering Time, Standby Time, and Productive Time) which, together with Non-Scheduled Time, comprise the six basic equipment states. Equipment Downtime for a given tool is divided into Unscheduled Downtime and Schedule Downtime. Likewise, Equipment Uptime for a given tool is divided into Engineering Time, Standby Time and Productive Time. Of these three Equipment Uptime states, Productive Time and Standby Time collectively represent the Manufacturing Time for a given tool.
The E10 Standard also defines a number of reliability, availability and maintainability measurements relating to equipment performance. Such measurements include, for example, mean (productive) time between interrupts (MTBI), mean (productive) time between failures (MTBF), mean (productive) time between assists (MTBA), mean cycles between interrupts (MCBI), mean cycles between failures (MCBF), and mean cycles between assists (MCBA). Mean (productive) time between interrupts (MTBI) indicates the average time that the tool or equipment performed its intended function between interrupts, and is calculated as the productive time divided by the number of interrupts during that time. Mean (productive) time between failures (MTBF) indicates the average time the tool or equipment performed its intended function between failures, and is calculated as the productive time divided by the number of failures during that time. Mean (productive) time between assists (MTBA) indicates the average time the tool or equipment performed its intended function between assists, and is calculated as the productive time divided by the number of assists during that time. Mean cycles between interrupts (MCBI), mean cycles between failures (MCBF), and mean cycles between assists (MCBA) are similar, but relate the number of tool or equipment cycles to the number of interrupts, failures and assists, rather than the productive time. The E10 Standard also provides guidelines for calculating equipment dependent uptime, supplier dependent uptime, operational uptime, mean time to repair (average time to correct a failure or an interrupt), mean time off-line (average time to maintain the tool or equipment or return it to a condition in which it can perform its intended function), equipment dependent scheduled downtime, supplier dependent scheduled downtime, operational utilization, and total utilization. The E10 Standard provides for calculation of two important metrics in particular: Overall Equipment Effectiveness (OEE), and Overall Fabrication Effectiveness (OFE). Traditionally, most of the information used to calculate the metrics in the E10 Standard has been gathered manually—a slow, tedious process prone to potential errors.
Since its inception, the E10 Standard has been refined and improved upon. In recent years, at least two new standards have been proposed or adopted by SEMI, the same entity that originally proposed the E10 Standard. The first of these new standards is known as the E58-0697 Automated Reliability, Availability and Maintainability Standard (ARAMS) (hereinafter the “E58 Standard”), and the second is known as the E79 Standard for Definition and Measurement of Equipment Productivity (hereinafter the “E79 Standard”). The E58 Standard was proposed around 1997 in an attempt to integrate automated machine processes into the E10 Standard. Accordingly, the E58 Standard specifies triggers for state transitions described in the E10 Standard, with the intent of encouraging tool or equipment manufacturers to store and make available trigger information at each tool. As the
Brooks Automation Inc.
Perman & Green LLP
Picard Leo
Pickreign Richard
Swindell W. Russell
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