Data processing: generic control systems or specific application – Specific application – apparatus or process – Mechanical control system
Reexamination Certificate
1998-04-24
2001-05-08
Sheikh, Ayaz (Department: 2155)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Mechanical control system
C700S121000, C700S274000, C055S356000, C055S385200, C454S187000
Reexamination Certificate
active
06230080
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a monitoring system and method for monitoring a clean room regulating system. More particularly, the monitoring system determines the operational state of the regulating system by transferring signals from the regulating system through an interface to a host computer.
2. Description of the Related Art
High-tech industries including the electronics industry require a clean, consistently maintained fabrication environment which meets certain cleanliness criteria. Most of the fabrication processes of highly-integrated semiconductor devices are carried out in such “clean rooms.” Clean room conditions, including temperature, humidity, air flow rate, pressure difference and particle distributions, can greatly affect the yield of semiconductor device production. Therefore, air quality in a clean room should be regularly checked to ensure that cleanliness criteria in terms of number of particles per unit volume are being met. Other air quality parameters such as air temperature, humidity, flow rate, and pressure also should be checked by a regulating system. Such a system therefore includes sensors for detecting the temperature and humidity of air in the clean room, a sensor for detecting the flow rate of air, a sensor for sensing the pressure difference between the inside and outside of the clean room, and a set of particle counters for checking the particle content in several sample volumes of air from which the distribution of particles inside the clean room can be inferred. Accordingly, these conditions are monitored using the above sensors.
However, such precise monitoring cannot be performed when any of the sensors of the regulating system, especially a particle counter, is not operating normally. Therefore, the sensors, especially the particle counters, should be periodically checked. This is usually done by a check performed at the site of the sensor. Because periodic checking at the site is difficult, it is often not performed until after the sensor has been operating in an abnormal state for some time. As a result, much of the data monitored from the regulating system is unreliable for the time period between the last periodic check and the discovery of an abnormally operating sensor.
Accordingly, there is a need for a more efficient means of monitoring both a clean room maintained by a regulating system and the sensors of the regulating system itself.
SUMMARY OF THE INVENTION
The present invention is directed to a monitoring system and method for checking a clean room and regulating system which substantially overcomes one or more of the problems presented by prior art systems and methods. Another object of the present invention is to provide a monitoring system for checking the abnormal state of a clean room regulating system by providing the clean room's host computer with a self-examination function.
To achieve these and other advantages and in accordance with the purposes of the present invention, a monitoring system for monitoring a clean room regulating system, comprises a particle counter comprising a pump having a pumping state for pumping a fluid containing particles. The particle counter counts particles in the fluid and produces an analog particle signal indicative of an amount of particles detected. The particle counter also produces a pump-state signal corresponding to the pumping state. A signal processor is included for converting the analog particle signal into a first digital signal, for converting the pump-state signal into an analog pumping signal, and for converting the analog pumping signal into a second digital signal. A host computer is included for receiving the first digital signal and deriving the amount of particles detected, for receiving the second digital signal and deriving the pumping state, and for monitoring the pumping state and the amount of particles counted. A communication channel is also included for transferring the digital signals from the signal processor to the host computer.
Another aspect of the invention is a method for monitoring a clean room regulating system. The method includes choosing a self-examination function for checking a particle counter of a clean room regulating system, and selecting a particle counter to be monitored. Then the method involves monitoring a first digital signal corresponding to an amount of particles detected by the selected particle counter, and a second digital signal corresponding to a pumping state of the selected particle counter. The next step involves executing the self-examination function using the amount of particles detected, derived from the first digital signal, and using the pumping state, derived from the second digital signal. The results of the executed self-examination function are then displayed.
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IBM Technical Disclosure Bulletin vol. 36 No. 11, Nov. 1993.
An Yo-Han
Choi Jae-heung
Lee Jung-sun
Lim Ki-hwan
Jean Frantz B.
Jones Volentine, L.L.C.
Samsung Electronics Co,. Ltd.
Sheikh Ayaz
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