Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
1999-07-14
2004-04-27
Starks, Jr., Wilbert L. (Department: 2121)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C345S215000
Reexamination Certificate
active
06728590
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates, in general, to wafer fabrication systems.
2. Description of the Related Art
The production of semiconductor devices consists of many layers of chemical compounds applied to or removed from a silicon base. The base is a disk known as a “wafer”. Depending on wafer size and chip complexity, each wafer can contain 25 to several hundred separate identical chips.
Using photolithography, the pattern of electrical circuits for a given layer is captured on the wafer. The image is developed, and the wafer moves to another process, either adding or modifying a layer, or etching it out in the pattern of the lithographic image. This process is repeated many many times in many layers to get a full 3-D electronic circuit. The dimensions of these circuits are incredibly tiny. Present technology is in the range of 0.25 micron line width or feature size.
Wafer fabrication systems are utilized to manufacture semiconductor devices. A wafer fabrication system can be conceived of as being composed of production equipment and utility systems. Production equipment can be conceived of as being composed of functional units known in the art as “production tools.” Utility systems can be conceived of as being composed of functional units known in the art as “items of utility system equipment.”
Prior to the initial installation of a wafer fabrication system, the production equipment and utility systems are individually designed and integrated together using top down engineering design techniques in order to yield the wafer fabrication system. Each individual production equipment and utility system design, as well as the overall wafer fabrication system design, is typically recorded in its own equipment layout plan drawing.
Subsequent to the initial installation of a wafer fabrication system, it is common within the industry to take a “modular” approach to the production equipment and utility systems making up the wafer fabrication system. That is, the constituent parts of the production equipment and the utility systems are treated as functional members that can be independently added, modified, replaced, relocated, removed, or upgraded with only concern for impacts local to the modification, replacement, relocation, removal, or upgrade.
With respect to the manufacture of semiconductor devices, there are hundreds of different production tools utilized to apply or remove or condition the various layers within the semiconductor device. Additionally, there are dozens of different chemicals required to produce the desired effects. The different chemicals require separate distribution, or utility, systems to deliver them.
Use of the modular approach to production equipment and utility systems allows the piecemeal addition, modification, replacement, relocation, removal, and/or upgrading of production tools making up the production equipment and items of utility equipment making up the utility systems as new process steps become necessary, or when production tools are improved. In practice, there are many advantages to the modular approach. One advantage is that the modular approach is highly efficient and effectively allows an existing wafer fabrication system to continuously evolve over time in order to meet expanding demand and changing manufacturing procedures. In a sense, a wafer fabrication system resulting from the modular approach is the best system possible in that it is uniquely adapted to the needs at hand, a fact which arises from its evolutionary growth in response to a changing environment of present and future needs.
One significant disadvantage to a wafer fabrication system utilizing the modular approach is that its evolutionary growth pattern means that there is no overall conscious design, or plan, applicable to the wafer fabrication system which has been evolving for any significant length of time. In theory, this disadvantage could be overcome by maintaining extensive documentation about the wafer fabrication system as it evolved. In practice, this has not happened.
The semiconductor device manufacturing industry has been in the midst of sustained capacity expansion for years. To keep up with demand, companies have been installing and updating production equipment and items of utility system equipment on a need-driven basis. Consequently, many of today's semiconductor device wafer fabrication systems consist of a bewildering array of production tools and items of utility system equipment assembled together in response to past needs. While such wafer fabrication systems do work exceptionally well, they give rise to significant difficulties from the standpoint of facilities engineers attempting to manage, maintain, or upgrade such wafer fabrication systems.
One such difficulty arises from the lack of documentation, and consequent lack of understanding, concerning the interrelationships of the production tools composing the production equipment. Another difficulty arises from the lack of documentation, and consequent lack understanding, concerning the interrelationships of the items of utility system equipment composing the utility systems. Yet another difficulty arises from lack of documentation, and consequent lack understanding, concerning the interrelationships of the various production tools and items of utility system equipment. This lack of documentation and understanding exists since existing wafer fabrication systems, composed of production equipment made up of various and sundry production tools and utility systems made up of various and sundry items of utility system equipment, are the result of sustained evolution, often over a period of several years, in response to needs that had to be satisfied immediately (e.g., either to avoid a shutdown of the facility or to quickly ramp up for production of a new product or quantity of product).
The result of the foregoing described process or real-time installation and modification is a highly evolved sprawl of well-functioning production equipment which is often partially undocumented (that is, because of the rapid modification without documentation, the original equipment layout plan drawings quickly become inaccurate representations of the production equipment and utility systems making up a wafer fabrication system). That is, since the production tools (and their supporting items of utility system equipment) had to be installed and/or modified virtually in real time, time for documenting such installations/modifications did not typically exist at the time of such installations/modifications. Furthermore, rapid growth in the industry has also typically meant that one real-time project has followed on the heels of a preceding real-time project. Consequently, often, time is not available to go back and document the changes in production tools and their supporting distribution systems which gave rise to existing production equipment. Thus, existing wafer fabrication systems are in the main vastly undocumented. This lack of documentation gives rise to a corresponding lack of information regarding the overall system functioning.
Incomplete documentation and overall wafer fabrication system understanding poses several grave difficulties to facilities engineers due to the overwhelming complexity of existing systems. The following example of an existing system will help to demonstrate a few of the difficulties arising from such complexity and lack of documentation.
At the NEC Electronics, Inc. semiconductor device manufacturing facility in Roseville, California, there are literally hundreds of production tools in place, which, as discussed above, collectively make up the production equipment. A great number of the relationships and interrelationships of the production tools in place are poorly documented or undocumented for the reasons set forth above. In addition, connected to the production tools in place are the following utilities, many of which have relationships and interrelationships that are likewise undocumented. Thirty-five (35) bulk liquid chemica
Hartman Jr. Ronald D
NEC Electronics Inc.
Skjerven Morrill LLP
Starks, Jr. Wilbert L.
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