Patent Publication Number: US-2005125763-A1

Title: System and method for the online design of a reticle field layout

Description:
This application claims priority from U.S. Provisional Patent Application Ser. No. 60/484,104, filed on Jun. 30, 2003, and which is hereby incorporated by reference in its entirety. The present disclosure relates generally to the field of semiconductor manufacturing and, more particularly, to a system and method for reticle field layout design. 
    
    
     BACKGROUND  
      The semiconductor integrated circuit (IC) industry has experienced rapid growth. Technological advances in IC materials and design have produced generations of ICs where each generation has smaller and more complex circuits than the previous generation. However, these advances have increased the complexity of processing and manufacturing ICs and, for these advances to be realized, similar developments in IC processing and manufacturing have been needed.  
      Furthermore, as the IC industry has matured, the various operations needed to produce an IC may be performed at different locations by a single company or by different companies that specialize in a particular area. This further increases the complexity of producing ICs, as companies and their customers may be separated not only geographically, but also by time zones, making effective communication more difficult. For example, a first company (e.g., an IC design house) may design a new IC, a second company (e.g., an IC foundry) may provide the processing facilities used to fabricate the design, and a third company may assemble and test the fabricated IC. A fourth company may handle the overall manufacturing of the IC, including coordination of the design, processing, assembly, and testing operations.  
      Whether in the context of a single facility or multiple facilities, communication issues may present problems in a number of areas, such as in the fabrication of IC&#39;s designed by a customer. For example, in IC manufacturing processes that use a photomask (mask), the mask contains one or more circuit patterns that are projected onto a wafer. The patterns may be laid out on the mask using a reticle field layout (RFL) process. The design of the RFL generally involves both the customer ordering the IC and engineers from a manufacturing facility. However, as there is currently no standardized framework within which the customer may submit an RFL design, the customer may provide their RFL design to a manufacturing facility using a number of different formats. This introduces additional complexity into the design process, as engineers from the manufacturing facility may need to enter the data provided by the customer and communicate with the customer regarding aspects of the RFL that are unclear or incorrect.  
      Accordingly, what is needed is a system and method for improving RFL design capabilities and communicating the RFL design to a manufacturing facility. For example, it is desired to provide online communication, a standard framework and format, and a set of built-in specification and design rules. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a flowchart of an exemplary method for designing a reticle field layout (RFL).  
       FIG. 2  is a block diagram of one embodiment of a virtual fabrication (fab) system within which the method  100  of  FIG. 1  may be performed.  
       FIG. 3  is a block diagram illustrating one possible implementation of the virtual fab of  FIG. 2 .  
       FIG. 4  is a block diagram of an exemplary computer that may be used within the virtual fab of FIGS.  2  or  3 .  
       FIG. 5  is a block diagram of an exemplary RFL design system that may be used within the virtual fab of FIGS.  2  or  3 .  
       FIG. 6  is an exemplary interface that enables a user to interact with the RFL design system of  FIG. 5 .  
       FIG. 7  is a flowchart of another exemplary method for designing a RFL.  
       FIGS. 8A and 8B  illustrate exemplary RFL designs that may be created using the method of  FIG. 7 .  
       FIGS. 9A-9C  illustrate exemplary RFL designs that may be created using the method of  FIG. 7 . 
    
    
     DETAILED DESCRIPTION  
      The present disclosure relates generally to the field of semiconductor manufacturing and, more particularly, to a system and method for reticle field layout (RFL) design.  
      It is understood, however, that the following disclosure provides many different embodiments, or examples, for implementing different features of the invention. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.  
      Referring now to  FIG. 1 , in one embodiment, a method  100  enables the creation, storage, and validation of a reticle field layout (RFL) design for an integrated circuit (IC). The RFL defines a mask that is used during photolithography to place circuits onto the IC. In the present example, the RFL design is created by a user who may enter RFL design information via an interactive interface, such as may be accessed using a web browser. In step  102 , the RFL design information is received from the interactive interface by a manufacturing facility, such as a design or fabrication facility. As will be described later in greater detail, the RFL design information may include the selection of IC manufacturing technologies that are associated with the mask, including information like the use of a 300 mm wafer and 0.13 micron technology.  
      In step  104 , the received RFL design is automatically verified using a set of predefined design rules to ensure the integrity of the design. In step  106 , the RFL design information is associated with a Layout Design Reference identifier (LDRID) that is used to associate the RFL design with other information relevant to the order, and is stored in a database that is accessible to the manufacturing facility. This enables the manufacturing facility to locate the RFL design and use it during the manufacturing process of the proper order. In step  108 , the RFL design is retrieved from the database and used to create a mask.  
      The method  100  may be used to extend customer service so that a customer can independently (e.g., without engineering support from the manufacturing facility) design a RFL using built-in design specifications and rules. The method  100  may also reduce photomask production cycle time by minimizing or eliminating the time and effort needed to communicate and confirm a design.  
      Referring now to  FIG. 2 , a virtual IC fabrication system (a “virtual fab”)  200  is one embodiment of a system that can be used to implement the method  100  of  FIG. 1 . The virtual fab includes a plurality of entities, represented by one or more internal entities  202  and one or more external entities  204  that are connected by a communications network  206 . The network  206  may be a single network or may be a variety of different networks, such as an intranet and the Internet, and may include both wireline and wireless communication channels.  
      In the present example, the internal entities  202  represents those entities that are directly responsible for producing the end product, such as a wafer or individually tested IC devices. Examples of internal entities  202  include an engineer, customer service personnel, an automated system process, a design or fabrication facility and fab-related facilities such as raw-materials, shipping, assembly or test. Examples of external entities  204  include a customer, a design provider; and other facilities that are not directly associated or under the control of the fab. In addition, additional fabs and/or virtual fabs can be included with the internal or external entities. Each entity may interact with other entities and may provide services to and/or receive services from the other entities.  
      It is understood that the entities  202 - 204  may be concentrated at a single location or may be distributed, and that some entities may be incorporated into other entities. In addition, each entity  202 ,  204  may be associated with system identification information that allows access to information within the system to be controlled based upon authority levels associated with each entities identification information.  
      The virtual fab  200  enables interaction among the entities  202 - 204  for purposes related to IC manufacturing, as well as the provision of services. In the present example, IC manufacturing can include one or more of the following steps: 
          receiving or modifying a customer&#39;s IC order of price, delivery, and/or quantity;     receiving or modifying an IC design;     receiving or modifying a process flow;     receiving or modifying a circuit design;     receiving or modifying a mask change;     receiving or modifying testing parameters;     receiving or modifying assembly parameters; and     receiving or modifying shipping of the ICs.        

      One or more of the services provided by the virtual fab  200  may enable collaboration and information access in such areas as design, engineering, and logistics. For example, in the design area, the customer  204  may be given access to information and tools related to the design of their product via the fab  202 . The tools may enable the customer  204  to perform yield enhancement analyses, view layout information, and obtain similar information. In the engineering area, the engineer  202  may collaborate with other engineers  202  using fabrication information regarding pilot yield runs, risk analysis, quality, and reliability. The logistics area may provide the customer  204  with fabrication status, testing results, order handling, and shipping dates. It is understood that these areas are exemplary, and that more or less information may be made available via the virtual fab  200  as desired.  
      Another service provided by the virtual fab  200  may integrate systems between facilities, such as between a facility  204  and the fab facility  202 . Such integration enables facilities to coordinate their activities. For example, integrating the design facility  204  and the fab facility  202  may enable design information to be incorporated more efficiently into the fabrication process, and may enable data from the fabrication process to be returned to the design facility  204  for evaluation and incorporation into later versions of an IC.  
      Referring now to  FIG. 3 , a virtual fab  300  illustrates a more detailed example of the virtual fab  200  of  FIG. 2 . It is understood, however, that the details mentioned and described in  FIG. 3  are provided for the sake of example, and that other examples can also be used.  
      The virtual fab  300  includes a plurality of entities  302 ,  304 ,  306 ,  308 ,  310 , and  312  that are connected by a communications network  314 . In the present example, the entity  302  represents a service system, the entity  304  represents a customer, the entity  306  represents an engineer, the entity  308  represents a design/lab facility for IC design and testing, the entity  310  represents a fab facility, and the entity  312  represents a process (e.g., an automated fabrication process). Each entity may interact with other entities and may provide services to and/or receive services from the other entities.  
      The service system  302  provides an interface between the customer and the IC manufacturing operations. For example, the service system  302  may include customer service personnel  316 , a logistics system  318  for order handling and tracking, and a customer interface  320  for enabling a customer to directly access various aspects of an order.  
      The logistics system  318  may include a RFL design system  324 , a product data management system  326 , a lot control system  328 , and a manufacturing execution system (MES)  330 . As will be discussed in greater detail with reference to  FIG. 5 , the RFL design system  324  may contain hardware and software for creating an RFL design. The product data management system  326  may manage product data and maintain a product database (not shown). The product database could include product categories (e.g., part, part numbers, and associated information), as well as a set of process stages that are associated with each category of products. The lot control system  328  may convert a process stage to its corresponding process steps.  
      The MES  330  may be an integrated computer system representing the methods and tools used to accomplish production. In the present example, the primary functions of the MES  330  may include collecting data in real time, organizing and storing the data in a centralized database, work order management, workstation management, process management, inventory tracking, and document control. The MES  330  may be connected to other systems both within the service system  302  and outside of the service system  302 . Examples of the MES  330  include Promis, Workstream, Poseidon, and Mirl-MES. Each MES may have a different application area. For example, Mirl-MES may be used in applications involving packaging, liquid crystal displays (LCDs), and printed circuit boards (PCBs), while Promis, Workstream, and Poseidon may be used for IC fabrication and thin film transistor LCD (TFT-LCD) applications. The MES  330  may include such information as a process step sequence for each product.  
      The customer interface  320  may include an online system  332  and an order management system  334 . The online system  332  may function as an interface to communicate with the customer  304 , other systems within the service system  302 , supporting databases (not shown), and other entities  306 - 312 . The order management system  334  may manage client orders and may be associated with a supporting database (not shown) to maintain client information and associated order information.  
      Portions of the service system  302 , such as the customer interface  320 , may be associated with a computer system  322  or may have their own computer systems. In some embodiments, the computer system  322  may include multiple computers ( FIG. 4 ), some of which may operate as servers to provide services to the customer  304  or other entities. The service system  302  may also provide such services as identification validation and access control, both to prevent unauthorized users from accessing data and to ensure that an authorized customer can access only their own data.  
      The customer  304  may obtain information about the manufacturing of its ICs via the virtual fab  300  using a computer system  336 . In the present example, the customer  304  may access the various entities  302 ,  306 - 312  of the virtual fab  300  through the customer interface  320  provided by the service system  302 . However, in some situations, it may be desirable to enable the customer  304  to access other entities without going through the customer interface  320 . For example, the customer  304  may directly access the fab facility  310  to obtain fabrication related data.  
      The engineer  306  may collaborate in the IC manufacturing process with other entities of the virtual fab  300  using a computer system  338 . The virtual fab  300  enables the engineer  306  to collaborate with other engineers and the design/lab facility  308  in IC design and testing, to monitor fabrication processes at the fab facility  310 , and to obtain information regarding test runs, yields, etc. In some embodiments, the engineer  306  may communicate directly with the customer  304  via the virtual fab  300  to address design issues and other concerns.  
      The design/lab facility  308  provides IC design and testing services that may be accessed by other entities via the virtual fab  300 . The design/lab facility  308  may include a computer system  340  and various IC design and testing tools  342 . The IC design and testing tools  342  may include both software and hardware.  
      The fab facility  310  enables the fabrication of ICs. Control of various aspects of the fabrication process, as well as data collected during the fabrication process, may be accessed via the virtual fab  300 . The fab facility  310  may include a computer system  344  and various fabrication hardware and software tools and equipment  346 . For example, the fab facility  310  may include an ion implantation tool, a chemical vapor deposition tool, a thermal oxidation tool, a sputtering tool, and various optical imaging systems, as well as the software needed to control these components.  
      The process  312  may represent any process or operation that occurs within the virtual fab  300 . For example, the process  312  may be an order process that receives an IC order from the customer  304  via the service system  302 , a fabrication process that runs within the fab facility  310 , a design process executed by the engineer  306  using the design/lab facility  308 , or a communications protocol that facilities communications between the various entities  302 - 312 .  
      It is understood that the entities  302 - 312  of the virtual fab  300 , as well as their described interconnections, are for purposes of illustration only. For example, it is envisioned that more or fewer entities, both internal and external, may exist within the virtual fab  300 , and that some entities may be incorporated into other entities or distributed. For example, the service system  302  may be distributed among the various entities  306 - 310 .  
      Referring now to  FIG. 4 , an exemplary computer  400 , such as may be used within the virtual fab  200  of  FIG. 2  or virtual fab  300  of  FIG. 3 , is illustrated. The computer  400  may include a central processing unit (CPU)  402 , a memory unit  404 , an input/output (I/O) device  406 , and a network interface  408 . The network interface may be, for example, one or more network interface cards (NICs). The components  402 ,  404 ,  406 , and  408  are interconnected by a bus system  410 . It is understood that the computer may be differently configured and that each of the listed components may actually represent several different components. For example, the CPU  402  may actually represent a multi-processor or a distributed processing system; the memory unit  404  may include different levels of cache memory, main memory, hard disks, and remote storage locations; and the  1 / 0  device  406  may include monitors, keyboards, and the like.  
      The computer  400  may be connected to a network  412 , which may be connected to the networks  206  ( FIG. 2 ) or  314  ( FIG. 3 ). The network  412  may be, for example, a complete network or a subnet of a local area network, a company wide intranet, and/or the Internet. The computer  400  may be identified on the network  412  by an address or a combination of addresses, such as a media control access (MAC) address associated with the network interface  408  and an internet protocol (IP) address. Because the computer  400  may be connected to the network  412 , certain components may, at times, be shared with other devices  414 ,  416 . Therefore, a wide range of flexibility is anticipated in the configuration of the computer. Furthermore, it is understood that, in some implementations, the computer  400  may act as a server to other devices  414 ,  416 . The devices  414 ,  416  may be computers, personal data assistants, wired or cellular telephones, or any other device able to communicate with the computer  400 .  
      Referring now to  FIG. 5 , in another embodiment, the RFL design system  324  is illustrated in greater detail. It is understood that, although the RFL design system  324  is shown as a component of the logistics system  318  in  FIG. 3 , the RFL design system  324  may actually be a separate entity or may be formed using existing entities, such as the design/lab facility  308  and the online system  332  of the customer interface  320 . In the present example, the RFL design system  324  is connected to the network  314 , and includes an RFL design framework  502 , an RFL design database  504 , and a set of RFL design specification and rules  506 .  
      The RFL design framework  502  may include an online accessible interface (which may be the online system  332 ), a standard design format and template, and data processing software and hardware. The RFL design database  504  may include an RFL database to store RFL design data received from the RFL design framework  502  and which is retrievable by an LDRID, and a customer database to store customer data and photomask order information. The RFL design specification and rules  506  may include multiple sets of specifications and associated rules for IC manufacturing technologies. For example, the RFL design specification and rules  506  may include rules needed to produce an IC using a  300  mm wafer, a  0 . 13  micron feature size, and BiCMOS technology. The RFL design system  324 , either separately or in conjunction with the service system  302  in the virtual fab  300  ( FIG. 3 ), may provide an RFL design platform with online communication, a standard format, and built-in specifications and design rules to both customers and engineers.  
      Referring now to  FIG. 6 , an interface  600  illustrates one means by which a customer may interact with the online accessible interface of the RFL design system  324  of  FIG. 5 . It is understood that a variety of interfaces may be presented to the customer, such as a login interface and a help interface that provides the customer with instructions on how to accomplish various tasks. After the customer logins to the RFL design system, the interface  600  presents the customer with several options. In the present example, the interface  600  includes a Load button  602 , a Save button  604 , an Auto place button  606 , a Remove button  608 , a Distance button  610 , an Edge button  612 , a Center button  614 , a Duplicate button  616 , and a Replace button  618 . The interface  600  may also include a template  620  that provides the customer with a basic RFL design layout. The template  620  may be updated by the RFL design specification and rules  506  during the design process to ensure that the RFL design is correct. Alternatively, the RFL design specification and rules  506  may be applied to the template  620  after the design is completed.  
      The Load and Save buttons  602 ,  604  provide the customer with the option to either load a draft RFL design from or save a draft RFL design to the RFL design database. The Auto place button  606  may place a design component in a recommended area (e.g., using the RFL design specification and rules  506 ). The Remove button  608  enables the customer to remove a component from the RFL design, while the Distance button  610  enables the customer to specify a distance between components or from the edge. For example, activating the Distance button  612  may bring up a user selectable menu or may present a box into which the customer can enter a desired distance.  
      The Edge button  612  may be used to specify a distance around the edge of the design, while the Center button  614  may enable the customer to center a component, either within the layout or relative to another component. The Duplicate button  616  may enable the customer to duplicate an existing component or an existing parameter (e.g., orientation, alignment, etc.). The Replace button  618  may enable a selected component to be replaced by another component. It is understood that the buttons and functions are illustrative, and that many other buttons and functions may be provided. For example, a context sensitive menu may be activated by clicking on a mouse button (not shown) or by using a keyboard (not shown). Accordingly, the interface  600  may be altered as desired to extend its functionality and to maximize customer support during the RFL design process.  
      Referring now to  FIG. 7 , and with additional reference to  FIGS. 8A and 8B , in still another embodiment, a method  700  may be used in conjunction with the interface  600  of  FIG. 6  to provide RFL design capabilities within a virtual fab. In step  702 , RFL information is received via the interface  600 . Referring also to  FIGS. 8A and 8B , an exemplary reticle field layout  800  is illustrated. The RFL information received in step  702  details one or more patterns that are to be transferred to a photomask for use in photolithography. As described previously, in IC manufacturing, a photomask is used to pattern a wafer for one or more electric circuits. The mask contains a pattern (defined by the RFL process) which details the circuits. The pattern, which may occupy a relatively small area on the mask, is projected onto the wafer during the fabrication process of an IC. If a customer wants to produce only one type of IC, then the same pattern may be repeated on the mask to form a matrix (e.g., five rows by four columns), such as is illustrated in  FIG. 8A . In  FIG. 8A , the symbol ‘A’ represents a single type of pattern  802 . Because the RFL defines how the patterns are placed on a mask, an RFL having a matrix of one pattern is relatively simple.  
      However, the customer may want to produce more than one type of IC on a wafer (referred to as a “combo job”). This means that multiple patterns need to be formed on a single mask, with each pattern having its own structure and dimensions. Generally, a mask may have multiple patterns, although the number of patterns may depend on such issues as wafer surface capacity and design specifications/rules.  FIG. 8B  illustrates an example of a RFL with a combo job, where the symbols ‘A,’ ‘B,’ and C’ represent different patterns  804 ,  806 , and  808 , respectively.  
      Referring now to  FIG. 9A  and with continued reference to  FIG. 7 , a RFL design  900  mirrors the RFL of  FIG. 8B . The RFL design  900  in  FIG. 9A  contains patterns  902 ,  904 , and  906 , which are different patterns. The line  908  is a scribe line, which is a space on a wafer between die that aids in the separation of the die. In the present example, the information received in step  702  is represented in  FIG. 9A  and is the first draft of a RFL that was completed by the customer. In step  704 , the RFL design  900  is verified using the RFL design specification and rules  506  of the design system  324  of  FIG. 5 . In step  706 , a determination is made as to whether the design is correct in light of the RFL design specification and rules  506  applied in step  704 . If the design is not correct, the user is prompted for corrections in step  708  and the method  700  returns to step  704  for verification. It is understood that other verification methods are possible, and that the design may be verified as each component is added by the customer or later in the design process. Because of this verification step, the RFL design  900  is known to be compatible with available manufacturing technology, and need not be confirmed by an engineer during manufacturing. If the design is correct, the method  700  continues to step  710 , where the design is stored in a database with a LDRID. In step  712 , the RFL design  900  may be retrieved from the database using the LDRID and, in step  714 , various modifications may be made.  
      Referring now to  FIG. 9B  and with continued reference to  FIG. 7 , the RFL  900  illustrates modifications made during step  714 . The RFL  900  of  FIG. 9B  includes additional portions  910 ,  912 ,  914 , and  916 . The additional portions may include test patterns, frame cells, and similar modifications. The test patterns may be electric circuits used by an IC fab (e.g., the fab facility  310  of  FIG. 3 ) to optimize yields, provide process control feedback, and assure device quality. The frame cells may be structures used for photomask registration and alignment. Because the RFL design  900  is accessible via the RFL design system  324  ( FIG. 5 ), engineers may make modifications directly to the RFL design  900  or may work with a copy. This prevents errors that may otherwise occur due to converting between file formats, entering customer information from paper, or using similar, non-standardized methods. Simulation tools may be used to optimize the layout of the patterns  902 ,  904 ,  906 , and to add the test patterns and frame cells. The method  700  then continues to step  716 , where the RFL design  900  is finalized.  
      Referring now to  FIG. 9C  and with continued reference to  FIG. 7 , the finalized RFL design  900  includes an additional portion  918 , which may be a special test pattern or frame cell. The finalized RFL design  900  includes any special requests from the customer or/and engineers that may not be automatically processed by designing tools. For example, a certain test pattern may need to be placed vertically, or a special arrangement and design may be needed if the scribe line  908  is not able to take the test patterns and frame cells. The finalized RFL design  900  may then be sent for mask preparation. Alternatively, the finalized RFL design  900  may be stored in the database and retrieved again later using the LDRID.  
      The present disclosure has been described relative to a preferred embodiment. Improvements or modifications that become apparent to persons of ordinary skill in the art only after reading this disclosure are deemed within the spirit and scope of the application. It is understood that several modifications, changes and substitutions are intended in the foregoing disclosure and in some instances some features of the invention will be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.