Abstract:
An integrated material transport system in an integrated circuit manufacturing factory is disclosed. The system comprises a first material transport subsystem traveling at a first height, and a second material transport subsystem traveling at a second height. There is at least one shared material transfer port to be used by both the first and second transport subsystems. Further, there is an integrated rail subsystem servicing both the first and second material transport subsystems for exchanging predetermined materials through the shared material transfer port with a predetermined material stocker under a ceiling with a uniform height.

Description:
BACKGROUND  
       [0001]     The present disclosure relates to material management techniques in an integrated circuit factory, and more particularly, relates to methods for integrating separate interbay and intrabay material transport systems into a single efficient transport system.  
         [0002]     The manufacture of integrated circuits (IC) requires many production process steps. The process tools used within specific processing areas or production bays of a typical high-volume production facility are usually segregated by a common characteristic. This common characteristic may include the production tool type, process type and/or production process sequence. During the production flow of an IC, the production material may visit many different production bays as well as the same bay(s) many times. IC manufacturing factories have set up automation-controlled production material handling systems to help transport the material in various stages of completion within the production facility to and from the production bays. In addition, these material transport systems are also used to transport material between storage or stocking locations for holding material in cue for processing.  
         [0003]     The block diagram shown in  FIG. 1  illustrates the use of material transport systems to move material in a typical IC factory  100 . Production bays X  102 , Y  104  and Z  106  are shown, comprised of bay production tools X  108 , Y  110  and Z  112  and bay stockers X  114 , Y  116  and Z  118 . The bay production tools X  108 , Y  110  and Z  112  and bay stockers X  114 , Y  116  and Z  118  are themselves usually not transportable and are established as fixtures within their assigned production bays X  102 , Y  104  and Z  106 , respectively. An Over Head Transport (OHT) system  120  transports the production material within (intrabay) each production bay X  102 , Y  104  or Z  106 , i.e., between the bay&#39;s stocker X  114 , Y  116  or Z  118  and the bay&#39;s production tool X  108 , Y  110  or Z  112 , as well as between the various production bay tools contained within each bay. The OHT system  120  also moves material in and out of the bay stockers X  114 , Y  116  or Z  118  to other bay stockers X  114 , Y  116  or Z  118  (interbay). Production material is usually held within a transport pod or a cassette fixture during transport by the OHT system  120 . A typical OHT system  120  is constructed as either a rail or conveyor system located above the manufacturing tools and work areas, with attached platforms or vehicles for moving the pods or cassettes on predetermined routes or tracks. The OHT system  120  may have many platforms/vehicles not necessarily unique to, nor assigned to any specific stocker or bay. The OHT system  120  serves as the primary system for moving production material throughout the manufacturing facility.  
         [0004]      FIG. 1  also illustrates an Over Head Shuttle (OHS)  122  system. The OHS system  122  is a higher speed, higher volume transport system to move production material between (interbay) production bays X  102 , Y  104  and Z  106 . The OHS system  122  supplements the movement of material by the OHT system  120 . The typical OHS system  122  is constructed as either a rail or other conveyor system located above the manufacturing tools  108 - 112 , work areas and the OHT system  120 . The rails of a typical OHS system are usually positioned at a different height (usually higher) than the rail section of a typical OHT system. The OHS system  122  also utilizes platforms or vehicles to move the pods or cassettes of production material on predetermined routes or tracks. The combined usage and routings of both OHT  120  and OHS  122  rail sections effectively facilitate production material movement throughout the entire IC manufacturing facility.  
         [0005]      FIG. 2  illustrates a plan view of a typical IC manufacturing facility with the OHT and OHS material transport systems as described by  FIG. 1 . The manufacturing facility  200  comprises of many production bays  202  with multiple production tools  204  located within each bay. An OHT rail section  206  provides transport access to each production bay  202  with transport routes/rails located within the production bays  202 , between the bay stockers  208  as well as along the main corridor  210  of the manufacturing facility  200 . The layout of the OHT rail section  206  establishes routes throughout the entire facility  200 , connecting intrabay and interbay areas.  
         [0006]     An OHS rail section  212  is also shown in  FIG. 2 . The OHS rail section  212  is located in the main corridor  210  of the manufacturing facility  200  and serves only as an interbay transport, connecting only to the bay stockers  208  of all production bays  202 . The transport area serviced by the OHS rail section  212  is a subset of the area serviced by the OHT rail section  206 .  
         [0007]     The integration of the OHT and OHS rail sections requires factory automation controls to effectively coordinate and schedule the activities of the two separate material transport systems throughout the entire facility. Coordination is required to utilize the advantage of interfacing a high speed, short route OHS transport system with the primary all-duty, all-purpose, long route OHT transport system. The automation control software for the two systems must also be sufficiently robust to prevent or minimize material movement/transfer conflicts and system deadlocks.  
         [0008]     Factory construction and layout planning must conform to the non-matching ceiling height requirements of both the OHT and OHS transport systems. Particularly, construction for and expansions to an OHS transport system may be costly if ceiling height is insufficient. IC manufacturing facilities are constructed as clean room environments. Construction costs for clean rooms are proportional to the clean room volume constructed. The higher ceiling height requirement for OHS systems adds extra construction cost premiums for the clean room space, attributed only to the OHS system. In addition, the operational costs related to maintaining the clean environment of the extra volume are also higher.  
         [0009]     What is needed is a well-integrated material transport system that does not require the high cost requirements of mismatched ceilings heights in the manufacturing facility. An efficiently integrated dual rail section that services both the interbay OHS and the intrabay OHT systems maintains the benefits of utilizing high-speed transports with moderate speed transport systems. Improved transfer methods between such dual rail sections may further improve the transfer volume and transfer times of the production material.  
       SUMMARY  
       [0010]     An integrated material transport system in an integrated circuit manufacturing factory is disclosed. The system comprises a first material transport subsystem traveling at a first height, and a second material transport subsystem traveling at a second height. There is at least one shared material transfer port to be used by both the first and second transport subsystems. Further, there is an integrated rail subsystem servicing both the first and second material transport subsystems for exchanging predetermined materials through the shared material transfer port with a predetermined material stocker under a ceiling with a uniform height.  
         [0011]     These and other aspects and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the disclosure.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a block diagram to illustrate the integration of material transport systems within a typical IC manufacturing facility.  
         [0013]      FIG. 2  is a plan view of a typical IC manufacturing facility illustrating the layouts of the material transport systems, rails, production bays, material stockers and production tools.  
         [0014]      FIG. 3  is a cross-sectional view of a typical IC manufacturing facility illustrating the positions of the material transport systems, rails, production bays, and material stockers.  
         [0015]      FIG. 4  is a cross-sectional view of an IC manufacturing facility illustrating the positions of the material transport systems, rails, production bays, and material stockers according to the methods of the present disclosure. 
     
    
     DESCRIPTION  
       [0016]     The present disclosure describes a method for integrating a low cost, dual rail/conveyor material transport system within an IC manufacturing facility. The integration methodology of the disclosure also improves material volume handling capability as well as improvement for material transfer rates at the material input and output transfer ports.  
         [0017]      FIG. 3  illustrates a cross-sectional view of a typical IC manufacturing facility with an integrated material transport system  300 . This view of the manufacturing facility shows a production bay  302 , its assigned material stocker  304  and the main corridor  306 , located just outside of the production bay  302 . An intrabay rail section  308  of a first material transport subsystem such as an over head transport (OHT) system  311  is shown located inside the production bay  302  with an intrabay OHT transfer port  310  used for the transfer of material between the material stocker  304  and the OHT  311 . This intrabay rail section  308  of the OHT system  311  provides transport service inside (intrabay) the production bay  302 . As shown, another interbay OHT rail section  312  and an interbay OHT material stocker transfer port  314  are located at the main corridor  306  side of the material stocker  304 . This interbay rail section  312  of the OHT system  311  provides transport service between (interbay) the stockers  304  of the production bays  302 . The ceiling height, Ct, of the production bay  302  is typically 3 to 5 meters, sufficient to accommodate both the hardware and rail requirements of the OHT system and the unobstructed work space clearance for production work.  
         [0018]     A rail section  316  of another material transport subsystem such as an over head shuttle (OHS) system  317  is also shown in  FIG. 3 . The interbay OHS transport rail section  316  is located outside of the production bay  302  in the manufacturing facilities&#39; main corridor  306 . The associated interbay OHS material transfer port  318  is located at the main corridor  306  side of the material stocker  304 . The interbay OHS system  317  and its associated interbay transfer port  318  are located at a height, Cs, that is sufficiently higher than that of the interbay OHT system  311  and production bay  302  ceiling height Ct. The interbay OHS system  317  requires a higher ceiling height Cs sufficient to accommodate the working hardware and rail of the system and the working hardware of the OHT system  311  located below it. The ceiling height as illustrated on  FIG. 3  as Cs, of a typical OHS system  317 , is usually 4 to 7 meters. Typical manufacturing facilities maintain the lower ceiling height Ct within the production bays  302  and the required higher ceiling height Cs in the fabrication areas encompassing the interbay OHS system  317 .  
         [0019]     Referring now to  FIG. 4 , there is shown a sectional side view of an IC manufacturing facility in accordance to the methods of the present disclosure. This view of the manufacturing facility shows a production bay  402 , its assigned material stocker  404  and the main corridor  406  located just outside of the production bay  402 . An intrabay rail section  408  of the OHT system  409  is shown located inside the production bay  402  with an intrabay OHT transfer port  410  used for the transfer of material between the material stocker  404  and OHT system  409 . The intrabay rail section  408  of the OHT system provides transport service inside (intrabay) the production bay  402 . The above-described components of the production facility are the same as that of the typical production facility as illustrated by  FIG. 3 . The ceiling height Ct of the production bay  402  may be the same height as or of minimal difference from the height as described in  FIG. 3 .  
         [0020]     Shown in  FIG. 4 , another OHT interbay rail section  412  and an interbay material stocker transfer port  414  are located at the main corridor  406  side of the material stocker  404 . This interbay rail section  412  of the OHT system  409  provides transport service between (interbay) the stockers  404  of the production bays  402 . Comparing to the system in  FIG. 3 , the interbay material transfer port  414  located on the main corridor  406  side of the production bay  402 , is expanded and larger than the typical interbay material transfer port  314  described in  FIG. 3 . This larger, expanded interbay port  414  serves as the material transfer port between the rail section of the OHT  412  and another rail section  416  for the OHS system  417  and the material stockers  404  of the present disclosure.  
         [0021]      FIG. 4  shows an interbay rail section  416  of the OHS transport system  417  located outside of the production bay  402 , in the manufacturing facilities&#39; main corridor  406 . The associated, shared interbay material transfer port  414  is shown located at the main corridor  406  side of the material stocker  404 . As previously stated, the interbay material transfer port  414  serves as the shared material transfer port for both rails of the OHT  409  and OHS  417  transport systems, for interface with the material stockers  404 .  
         [0022]     The shared interbay material transfer port  414  allows for the hardware of the OHS transport rail  416  to be located at a lower height than that as described for  FIG. 3 . For this example of the present disclosure, the ceiling height of the facility encompassing the OHS system  417  is at the same height as that of the production bay  402 , shown in  FIG. 4  as height Ct. The cross-sectional view shows the ceiling height of the entire manufacturing facility to be uniform at one height Ct, contrasted to the offset ceiling heights Ct and Cs illustrated in  FIG. 3 . for a typical manufacturing facility. It is noticed that although the rail sections are shown to be separate, they are integrated together to be controlled coherently. For example, they can be controlled through a single control module top make sure that there is no conflicts in the use of the rail anytime during the operation. As an alternative, the upper rail section  416  can be controlled by one control module, and the lower rail section  408 / 412  can be controlled by another control module, with both controller being further integrated together. In this sense, the rail including the upper and lower rail sections can be viewed as an integrated rail subsystem.  
         [0023]     The uniform ceiling height made available in this improved design can be accomplished by having a well-integrated dual rail design that accommodates both the interbay OHS and intrabay OHT material transport systems. The use of a single, shared port for material transfers in and out of the material stockers allows for the placement of the two rail sections closely together. With an expanded material transfer port opening that now extends up to the ceiling height of the production bay, the higher OHS transport system may be lowered to fit within this ceiling height.  
         [0024]     The uniform, lower ceiling height reduces the entire volume of the manufacturing facility, thus providing lower costs for clean room construction and maintenance. The use of the integrated transport, integrated dual rail/conveyor systems maintain the benefits of combining high speed, short route material transport with moderate speed, long route transport systems. The shared transfer ports between the OHT and OHS systems allow for more seamless integration of the factory automation controls for the coordination and scheduling of material movement on the dual transports. Seamless integration will lessen the probability for system conflicts and deadlocks as well as providing more efficient algorithms for controlling material movement.  
         [0025]     The shared transfer ports and lowered ceiling heights also provide improvements for material transfer rates. The distance material travels between the material stockers and transfer ports are shorter. Improved transfer rates and material movement efficiencies will improve overall capabilities of the transport systems for handling additional material volume.  
         [0026]     The above disclosure provides an example for implementing features of the invention. Specific examples of components and processes are described to help clarify the invention. These are, of course, merely examples and are not intended to limit the invention from that described in the claims.  
         [0027]     While the invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention, as set forth in the following claims.