1. Field of the Invention
The present invention relates to a method for controlling equipment in a semiconductor manufacturing system, and more particularly, to a method for automatically controlling process conditions that reflect actual operational capabilities of units within the equipment, through an unit monitoring module, to maximize the productivity of the system.
2. Description of the Related Art
Generally, the fabrication of semiconductor devices involves highly precise processes that require finely tuned precision equipment. Several pieces of precision equipment are typically employed in sequence and arranged on a semiconductor processing line. The operation of each piece of precision equipment on the line is closely monitored by operators to maintain and enhance the efficiency of the processing line.
As shown in FIG. 1, conventional fabrication equipment 3 are disposed on a conventional processing line. When a lot (not shown) of workpieces, such as wafers, are introduced into the equipment 3, the equipment 3 performs a fabrication process on the lot. The equipment 3 is connected on-line to a host computer 1 through an equipment server 4. An operator interface (O/I) 2, for example an operator interface personal computer (O/I PC), is also connected on-line to the host computer 1. Through the O/I 2, an operator informs the host computer 1 that a process using the equipment 3 is about to commence. The operator inputs basic manufacture data into the host computer 1, e.g., the identification number (ID) of the lot to be processed in the equipment 3 and the ID of the equipment 3 for performing the process with the lot.
Then, based on the input basic manufacture data, the host computer 1 searches its data base for the process condition data to be applied to the process on the lot. The host computer 1 immediately downloads these process condition data, including preset process settings, to the equipment. Process settings may include, for example, a desired process time duration or a desired process temperature.
Thereafter, the operator checks the process condition data and inputs a process commencing command or a process terminating command. The lot is then automatically and rapidly routed into and out of the equipment 3. In this manner, the process equipment 3 performs on the workpieces of each lot based on the process settings received.
The equipment 3 performs the processes on the lots by operating units or components of the equipment 3, e.g., loading and unloading ports (not shown), and chambers 5. While the equipment 3 performs the process on the lots, the operator closely monitors the operations of the units of the equipment 3 continuously. If it is recognized that a particular unit, e.g., a particular chamber 5, of the equipment 3 is in an non-operational state, because, for example, the particular unit is undergoing preventative maintenance or it is out of order, then the whole equipment is determined to be in the non-operational state. Consequently, the equipment is turned off to prevent production problems associated with introducing lots into non-operational chambers.
In the processing line, a transferring apparatus, e.g., an auto guided vehicle (AGV) 6, is included to automatically transfer lots among the equipment 3 and between bays of the fabrication facility. The AGV 6 is controlled by commands communicated from the host computer 1 to an on-line transfer apparatus server 7 and then transmitted by the transfer apparatus server to the AGV 6 via a communications link. The host computer 1 continuously communicates operational commands to the AGV 6 so that the AGV 6 can rapidly respond to perform the lot transferring function.
However, such a conventional controlling system suffers from several problems. First, even when only some of the units of the equipment 3 are non-operational and other units are operational, the operator considers the whole equipment 3 to be in the non-operational state. As a result, the equipment 3 is not fully utilized and the productivity of the processing line is not efficiently controlled.
Secondly, since it is very difficult for the operator to recognize the actual operating states of units in real time, equipment 3 with non-operational units may be considered to be in the operational state for some period of time. During this time delay, the operator may introduce lots into the equipment with process condition data designed for normal operations. In this case, an excessive number of lots may be introduced into the equipment compared to the number the equipment can actually handle. This over-introduction of lots may result in the accumulation of lots in the equipment. When lots accumulate in the equipment, the efficiency of the entire processing line is reduced.
Thirdly, even when the operator recognizes that some units are non-operational, the AGV is operated without any intervention of the operator, so that the over-introduction and accumulation of lots in the equipment may still occur, thus increasing the chances of over-introduction.