Abstract:
A backup control system within a fabrication system is provided. The fabrication system contains a plurality of separately located fabrication facilities, each of which contains a computer assisted production control system and a plurality of processing tools. The backup control system, coupled with the computer assisted production control systems, provides control of backup operations between the fabrication facilities, and relays manufacturing constraints of the backup-operated articles before and after the backup operation.

Description:
BACKGROUND  
       [0001]     The present invention relates to a fabrication control system and particularly to a fabrication control system capable of controlling fabrication backup applied in multiple fabrication facility locations.  
         [0002]      FIG. 1  is a schematic view showing a conventional fabrication system  100 , capable of fabricating semiconductor wafers, and containing Fabs  11  and  13 . Fabs  11  and  13  are not identical in tool composition, but have similar and/or partially overlapping tool sets. Fabs  11  and  13  contain tools  11   a ˜ 11   n  and  13   a ˜ 13   n  respectively. Tools  11   a ˜ 11   n  and  13   a ˜ 13   n  are controlled by Manufacturing Execution Systems (MESs)  110  and  130  respectively. Although both Fabs  11  and  13  belong to fabrication system  100 , they are not only geographically separated but also operate discretely. Because of the discrete operation, workloads allocated to Fab  11  cannot be processed in Fab  13 , and vice versa. Even though Fab  13  is available for providing backup operation, Fab  11  loading must wait for processing when a bottlenecked tool is backed up. Thus, some tools in Fab  13  may remain idle despite Fab  11  having wafer lots queued at a corresponding tool. The independent operation of Fabs  11  and  13  actually hinders fabrication system  100  from optimizing utilization.  
         [0003]     While cross-Fab backup within a fabrication system is clearly desired, it is not routinely practiced due to great difficulty in monitoring and controlling a plurality of separately located independent fabrication facilities. Cross-Fab backup is presently executed manually in the conventional fabrication system, an inefficient and mistake-prone process. Moreover, owing to the complexity of wafer fabrication, the conventional cross-Fab backup cannot address every detail of process operation, resulting in yield loss. In U.S. Patent Application 20020165629 (Backup control system for optimizing utilization of multiple fabrication facilities), Ho et al. disclose a backup control system and method for monitoring and controlling multiple fabrication facilities. The above-mentioned invention relieves the manual burden of conventional cross-Fab backup and enhances the overall utilization of the multiple fabrication facilities.  
         [0004]     In wafer fabrication processes, however, most work-in-process (WIP) has manufacturing constraints, based on process time, equipment, Advance Process Control (APC), and contamination. These manufacturing constraints are set to prevent mis-operation and yield loss. Both the conventional method and the cited disclosure fail to relay these manufacturing constraints between Fabs during cross-Fab backup, thereby increasing the likelihood of mis-operation and yield loss, and thus counteracting the benefits of cross-Fab backup operation.  
         [0005]     Hence, there is a need for a fabrication system that addresses mis-operation during cross-Fab backup arising from the existing technology.  
       SUMMARY  
       [0006]     It is therefore an object of the invention to provide a system and method of backup control to enhance the overall utilization of a fabrication system without yield loss. To achieve this and other objects, the present invention provides a system and method of relaying manufacturing constraints between separately located Fabs during cross-Fab backup.  
         [0007]     According to one embodiment of the invention, a backup control system is provided within a fabrication system. The fabrication system contains a plurality of separately located fabrication facilities, each of which contains a computer assisted production control system and a plurality of processing tools.  
         [0008]     The backup control system, coupled with the computer assisted production control systems, provides control of backup operations between the fabrication facilities, and relays manufacturing constraints of the backup-operated articles before and after the backup operation.  
         [0009]     According to another embodiment of the invention, a backup control method is provided controlling the backup operation of articles in the separately located fabrication facilities within the fabrication system mentioned above. First, a backup request is received from a first fabrication facility, wherein the backup request comprises identification codes of the backup-operated articles, backup operation, and support manufacturing facility. Second, a first manufacturing constraint is retrieved from the first manufacturing facility according to the identification codes of the backup-operated articles and the backup operation. Then the backup request and the first manufacturing constraint are transmitted to a second manufacturing facility according to the identification code of the support manufacturing facility. Next, a backup completion report is received from the second fabrication facility, wherein the backup completion report comprises identification codes for the backup-operated articles and a second manufacturing constraint. Then, the backup completion report is transmitted to the first fabrication facility.  
         [0010]     The above-mentioned method may take the form of program code embodied in a computer readable tangible media. When the program code is loaded into and executed by a machine, the machine becomes an apparatus for practicing the invention.  
         [0011]     A detailed description is given in the following embodiments with reference to the accompanying drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:  
         [0013]      FIG. 1  is a schematic view of a conventional fabrication system.  
         [0014]      FIG. 2  is a schematic view of a fabrication system according to one embodiment of the present invention.  
         [0015]      FIG. 3  is a flowchart of the backup control operation of the system in  FIG. 2 .  
         [0016]      FIG. 4  shows a backup request in accordance with the present invention.  
         [0017]      FIG. 5  is a diagram of a storage medium storing a computer program providing the backup control method of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0018]     The present invention will now be described with reference to FIGS.  2  to  5 , which in general relate to a backup control system within a fabrication system. While the preferred embodiment of the invention operates with semiconductor fabrication systems, it is understood that the type of article processed by the fabrication system is not critical to the present invention, and any fabrication system processing articles having dynamic manufacturing constraints may utilize the present invention.  
         [0019]      FIG. 2  is a schematic view of a fabrication system according to one embodiment of the present invention. The fabrication system  200  is a semiconductor fabrication system, and contains Fabs  21  and  23  and a backup control system  25 .  
         [0020]     Each Fab comprises a plurality of processing tools for performing various wafer fabrication functions and a manufacturing execution system (MES) for controlling the processing tools thereof. Fab  21 , for example, contains MES  210  and processing tools  21   a  to  21   n , wherein the processing tool  21   a  has photolithography function. Fab  23  contains MES  230  and processing tools  23   a  to  23   n , wherein the processing tool  23   a  also has photolithography function.  
         [0021]     Backup control system  25 , coupled with MES  210  and MES  230  through a network  27 , controls backup operations between Fabs  21  and  23 , and relays manufacturing constraints of the backup-operated wafer lots before and after the backup operation. When the capacity of processing tool  21   a  to process wafer lots scheduled to be processed by processing tool  21   a  is exceeded there is a need for backup operation. As mentioned above, since both processing tools  21   a  and  23   a  are capable of photolithography processing, processing tool  23   a  is a candidate for backup operation on behalf of processing tool  21   a . If processing tool  23   a  has suitable capacity and capability, then processing tool  21   a  sends a backup request to backup control system  25  requesting backup support from Fab  23 . The backup control system  25  receives the backup request, retrieves the corresponding manufacturing constraints, and relays the manufacturing constraints together with the backup request to Fab  23 . Fab  23  receives the backup request and the corresponding manufacturing constraints, and waits for the backup-due wafer lot. Processing tool  23   a  processes the wafer lot when it arrives. When the backup operation is accomplished, Fab  23  updates the manufacturing constraints, returns the processed wafer lot to Fab  21 , and sends a backup completion report to backup control system  25 . The backup control system  25  receives the backup completion report and the updated manufacturing constraints of the backup-operated articles from Fab  23 , and relays them to Fab  21 .  
         [0022]      FIG. 3  is a flowchart of the backup control operation of the system described above. The backup control method shown in  FIG. 3  is implemented in backup control system  25  for controlling backup control operation of wafer lots within the fabrication system  200 .  
         [0023]     First, a backup request is received from Fab  21  (step S 31 ) The content of the backup request is shown in  FIG. 4 . A backup request  40  contains fields for the lot ID of the backup-operated wafer lot (field  41 ), product ID of the backup-operated wafer lot (field  42 ), name of the request Fab (field  43 ), name of the support Fab (field  44 ), initiating step of the backup operation (field  45 ), and ending step of the backup operation (field  46 ).  
         [0024]     Second, manufacturing constraints corresponding to the backup-operated wafer lot are retrieved from MES  210  according to the lot ID of the backup-operated wafer lot and the steps scheduled to be executed in Fab  23  (step S 33 ).  
         [0025]     After the backup operation is accomplished, a backup completion report and updated manufacturing constraints are received from Fab  23  (step S 35 ) and transmitted to Fab  21  (step S 37 ). When Fab  21  receives the backup completion report and updated manufacturing constraints, it updates the manufacturing constraints of the backup-operated wafer lot accordingly. Then the wafer lot continues processing in Fab  21 .  
         [0026]     The backup control method implemented in the backup control system of the present invention, or certain aspects or portions thereof, may take the form of program code (i.e. instructions) embodied in a tangible media, such as floppy diskettes, CD-ROMS, hard drives, or any other machine-readable storage medium, wherein, when the program code is loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. The methods and apparatus of the present invention may also be embodied in the form of program code transmitted over some transmission medium, such as electrical wiring or cabling, through fiber optics, or via any other form of transmission, wherein, when the program code is received and loaded into and executed by a machine, such as a computer, the machine becomes an apparatus for practicing the invention. When implemented on a general-purpose processor, the program code combines with the processor to provide a unique apparatus that operates analogously to specific logic circuits.  
         [0027]      FIG. 5  is a schematic diagram of a storage medium for a computer program providing the backup control method according to the present invention. The computer program product includes a storage medium  510  having computer readable program code embodied in the medium for use in a computer system  500 , the computer readable program code comprising at least computer readable program code  511  receiving a backup request from a first fabrication facility, computer readable program code  512  retrieving a first manufacturing constraint from the first manufacturing facility according to the identification codes of the backup-operated articles and the backup operation, computer readable program code  513  receiving a backup completion report and updated manufacturing constraints from the second fabrication facility, and computer readable program code  514  transmitting the backup completion report and updated manufacturing constraints to the first fabrication facility.  
         [0028]     While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.