Abstract:
Wafer processing time and handling is reduced by coupling a retrofitable processing tool between two standard processing tools. In an example embodiment, the retrofitable tool includes a metrology unit, which is coupled between two processing tools, that provides metrology capability without having to remove the wafers from the processing line. Once the metrology process is complete the wafers are transferred to the next processing tool and the retrofitable tool is decoupled from the two processing tools. An important advantage is the increased processing flexibility that the processing line reconfiguration method and the retrofitable tool bring to wafer processing.

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to wafer processing tooling on a wafer processing line in a semiconductor processing plant and, more particularly, to providing flexibility to wafer processing by reconfiguring portions of the line whenever necessary. 
     BACKGROUND OF THE INVENTION 
     A conventional semiconductor processing plant typically includes multiple processing areas or bays interconnected by a path, such as a conveyor belt. Each bay generally includes the requisite processing tools (interconnected by a subpath) to process semiconductor wafers for a particular purpose, such as photolithography, chemical-mechanical polishing or chemical vapor deposition, for example. Material stockers or stocking tools generally lie about the plant and store semiconductor wafers waiting to be processed. Each material stocker typically services two or more bays and can hold hundreds of cassettes. The wafers are usually stored in cassettes in groups of about 25 wafers. The wafers are then disposed within a carrier and move from one process to another in the carrier. The carriers are usually tracked by their carrier code by a computer system as they move through the plant. 
     Once a wafer lot has been retrieved, and the equipment has been set up, the operation on the wafers by a particular piece of equipment, or “tool,” can begin. At this point, the lot is “moved-in” to the operation. An operator on the line then communicates this information to the host computer. The wafer lot remains in this state until the operation is completed. Once the operation is completed, the operator must perform tests and verifications on the wafers. When all tests and verifications have been performed, the host computer application program must be notified. Wafers may have moved from one cassette to another as a result of the operation; therefore the host application and computer have to be notified of these moves. The operator then places the cassette of “moved-out” wafers in the material stocker to await orders as to the location of the next piece of equipment that will perform operations on the wafers. 
     The semiconductor fabrication plant, including the bays, material stockers and the interconnecting path, typically operates under control of a distributed computer system running a factory management program. In this environment, the automated material handling system (AMHS) may conceptually include the cassettes, the transportation system (e.g., paths) and a control system (e.g., the distributed computer system). However, some of the key processes necessary to ensure that the line is operating properly, such as metrology, are usually located at a distance from where the wafers are currently being processed. It is necessary then to remove the wafers from the current processing tool and transport them back to the metrology area for measurements. This approach increases the number of times that the wafers are handled and increases cycle time in wafer processing. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to addressing the above and other needs in connection with improving wafer processing tool flexibility and in reducing cycle time as wafers move through the semiconductor plant. 
     According to one aspect of the invention, it has been discovered that wafer processing lines are reconfigurable to accommodate changes in wafer processing recipes or to reduce wafer handling in a cluster tool of a wafer processing system. It has also been discovered that wafers are processed faster by moving the metrology and sorting processes/functions closer to the main wafer processing tools. 
     According to one aspect of the invention, a method of configuring wafer processing equipment in a semiconductor processing plant having a material handling system is described. A plurality of wafer processing tools is provided that are adapted to process at least one wafer presented by the material handling system. A retrofitable tool or multi-tool adapter is then provided that is adapted to be integrated with at least one of the plurality of processing tools. The retrofitable tool includes a wafer transfer unit disposed thereon to facilitate the transfer of at least one wafer between the processing tools and the retrofitable tool. The retrofitable tool is then coupled to at least one of the plurality of processing tools so as to reconfigure the wafer processing line as a function of a wafer processing recipe. 
     According to another aspect of the invention, a retrofitable tool for configuring wafer processing equipment in a semiconductor processing plant is disclosed. The retrofitable tool is adapted to operate in a semiconductor processing plant that includes a material handling system and at least one processing tool. The retrofitable tool is composed of an enclosure that includes a storage unit adapted to hold at least one wafer. A coupler arrangement is disposed on one side of the enclosure and is adapted to couple the retrofitable tool to at least one processing tool. An input port is disposed on the enclosure and a wafer transfer unit is coupled to the storage unit to facilitate the transfer of at least one wafer between the processing tool and the enclosure. 
     In yet another aspect of the invention, a system for configuring wafer processing equipment in a semiconductor processing plant includes a first processing tool and a second processing tool adapted to process at least one wafer. The system also includes a retrofitable tool adapted to be temporarily integrated with the first and second processing tool. A coupling arrangement is disposed on the retrofitable tool and on the processing tools to enable the retrofitable tool to be coupled with at least one of the first and second processing tools. 
     The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures in the detailed description that follow more particularly exemplify these embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
     FIG. 1A is a retrofitable processing tool made in accordance with one embodiment of the invention; 
     FIG. 1B is the retrofitable tool of FIG. 1A made in accordance with another embodiment of the invention; 
     FIG. 2A illustrates a system for reconfiguring a wafer processing line in accordance with one embodiment of the invention; 
     FIG. 2B illustrates a system for reconfiguring a wafer processing line that operates with a material handling system in accordance with another embodiment of the invention; and 
     FIG. 3 is a process flow diagram of the manner in which the wafer processing line is reconfigured using the retrofitable tool in accordance with one embodiment of the invention. 
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     The present invention is generally directed to a method and apparatus for reconfiguring cluster tools and wafer processing lines in a semiconductor plant. The invention is particularly suited for moving metrology equipment and wafer handling equipment in and out of the wafer processing line. While the present invention is not necessarily limited to a wafer processing application the invention will be better appreciated using a discussion of exemplary embodiments in such a specific context. 
     In an example embodiment, a retrofitable processing tool or a multi-tool adapter is used for reconfiguring a wafer processing line. The retrofitable tool allows processing equipment, metrology equipment, wafer sorters and stockers and the automated material handling system to be coupled together to facilitate the transfer of wafer lots from one processing tool to the next without operator intervention. The multi-tool adapter is programmed to understand a set of commands that include loading/unloading wafers, transferring wafers and purging oxygen from a processing chamber. The retrofitable tool is composed of an expandable enclosure that includes a storage unit adapted to hold various wafers. A coupling device, such as a pin and lock assembly, is disposed on one side of the storage area and is adapted to couple the multi-tool adapter to at least one processing tool. An input port is disposed on the enclosure and a wafer transfer unit is coupled to the storage unit to facilitate single wafer transfer between the processing tool and the enclosure. 
     Referring now to the figures, FIG. 1A illustrates a multi-tool adapter (or retrofitable tool)  100  for reconfiguring wafer processing equipment in a semiconductor processing plant. Multi-tool  100  is coupled to a first processing tool  101  and, in this example, includes a sealed link enclosure  102  that has a storage unit  103  adapted to hold a set of wafers  104 . Tool  100  includes an input port  105  and a coupler arrangement  106  composed of an output port  108 , a seal  110  and a pin and lock assembly  112 . A wafer transfer unit  114  is coupled to the storage unit and facilitates the transfer of wafers  104  between processing tool  101  and enclosure  102 . Tool adapter  100 , in this example, includes a conveyor arrangement  116  coupled thereto for moving the tool adapter about the wafer processing area. The conveyor arrangement includes roller/wheel assemblies or an external forklift type device that carries the tool adapter to the processing tool to which it will be integrated. 
     In FIG. 1B, an example of tool adapter  100  illustrates the adaptability of size that the tool is expanded to, as in  118 A, or reduced to, as in  118 B, to accommodate the various sizes of processing tools that tool adapter  100  will adhere to. The walls of enclosure  102  are movable in horizontal direction to facilitate the size adjustment. In another example, tool adapter  100  is formed of concentric enclosures  102 , as in  118 C, to also accommodate processing tools of various sizes. Tool adapter  100  is illustrated to be movable in several directions (up to 360 degrees), as in  120  and the x-y-z axis shown, depending on the application. Multi-tool adapters include a metrology unit, a wafer coater, a stepper, a wafer stocker, a wafer sorter, a component integrity checker, a reticle sorter and an oxygen purging station or any other tool that performs a wafer processing/handling operation. 
     Referring now to FIG. 2A, the top view of a reconfigurable wafer processing system  200  for use in a semiconductor processing plant includes a first processing tool  202 , a second processing tool  204  and a third processing tool  206 , all of which are adapted to process wafers. Multi-tool adapters  208  and  210  are also included in system  200  that are adapted to be temporarily integrated with processing tools  202 ,  204  and  206  to configure new processing schemes. In this example, multi-tool adapter  208  includes a coupler assembly  202 A and  208 B, disposed on either side of adapter  208 , that enables tool  208  to be securely coupled between tools  202  and  204 . Tool  206  is decoupled from tools  202  and  204  and moved laterally out (as indicated by the arrows) while adapter  208  is temporarily moved into position. In this example, system  200  has been reconfigured to include a metrology unit between tools  202  and  204  to conduct metrology measurements in situ without having to remove the wafers as they move from the process of tool  202  to the process of tool  204 . Further, the wafer transfer units within adapter  208  facilitate wafer transfer between tools or chambers without the need for operator intervention or handling. This reduces the physical handling that can damage or contaminate the wafers. This approach also reduces cycle time in wafer processing in that the wafers need not be removed from one processing area and transported back and forth to another area of the plant for performing metrology measurements or to perform wafer sorting. 
     In this example, wafers are moved from tool  202  via the wafer transfer unit to adapter tool  208 . Once the operation of adapter tool  208  is complete, the wafers are transferred to tool  204  for further processing. Adapter tool  208  is now removeable and tool  206  is moved back into the original position of system  200 . In another embodiment, another adapter tool  210  is coupled to one end of system  200  as shown or is the metrology unit of tool  208  that is moved to the end of the process after tools  202 ,  204  and  206  are coupled together. 
     FIG. 2B exemplifies the side view of wafer processing system  200  operating with an automatic material handling system  212 . In this example, tool adapters  208  and  210  include communications modules,  208 C and  210 C respectively, which communicate the location of the adapter tools in the wafer processing system to material handling system  212 . Material handling system  212  is coupled to a computer arrangement  214  and to a database  216  for storing information on the location of the adapter tools in the wafer processing system. 
     Referring to FIG. 3, a flowchart  300  exemplifies how the wafer processing system  200  is reconfigured in accordance with an embodiment of the present invention. At block  302 , the processing tools are setup for processing the wafers and at block  304  various multi-tool adapters (MTA) are provided. At block  306 , a wafer processing recipe is provided. By way of example, a wafer moves through each processing tool of system  200  as dictated by the processing recipe. At  308 , a determination is made whether to rearrange the processing tool setup in view of the recipe. If the answer is yes, the flow moves to block  310  where an adapter tool is intergrated into system  20  and the processing tools are reconfigured to follow the recipe. The wafer processing line and equipment are configurable into several combinations depending on the wafer processing recipe provided for the wafer lot to be processed. The location of the adapter tool and the reconfigured system is then communicated to the AMHS (Automated Material Handling System) computer&#39;s database at block  312 . 
     If the determination at block  308  is made to not reconfigure the system due to the recipe, the flow moves to block  314  where a determination is made whether the cycle time of system  200  can be reduced by reconfiguring the system to include some of the adapter tools. Where cycle time reductions are possible, the flow moves to block  310  where an adapter tool is integrated into system  200  and the processing tools are reconfigured to follow a shortened processing path. For example, a metrology unit is coupled to system  200  rather than having to remove the wafers at system  200  and transporting them back and forth to the metrology area of the plant. The location of the adapter tool and the reconfigured system is then communicated to the plant. The location of the adapter tool and the reconfigured system is then communicated to the computer&#39;s database at block  312  for tracking purposes. After system  200  has been reconfigured, the wafers are processed at block  316 . At block  318 , the adapter tools are optionally decoupled if it is determined that a new processing recipe is to be used or reduced wafer handling is desired in the new processing tool configuration. 
     As noted above, the present invention is applicable to actively reconfiguring wafer processing systems of a wafer lot that is being processed. Accordingly, the present invention is not to be necessarily limited to the particular examples described above, but is intended to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification. The claims are intended to cover such modifications and devices.