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  Die-level traceability mechanism for semiconductor assembly and test facilityUSPTO Application #: 20080071413Title: Die-level traceability mechanism for semiconductor assembly and test facility Abstract: Embodiments of the present invention provide a novel method, system and computer program product for tracing die units during material transfer from, for example, one factory or lot to another (and efficiently maintaining correspondence between die data and an individual die during, e.g., a lot transfer process). One or more embodiments of the present invention are intended to improve the mechanism of die-level traceability by assigning individual die IDs to each die unit in, e.g., each lot, and associating a range of die IDs with a corresponding index string. When, for example, some dies are transferred from, e.g., a first lot to a second lot, the entire die information associated with the first lot is copied to the second lot, and a different index string is assigned to the second lot to indicate the actual dies or range of dies that have been transferred. The first lot's index string is then adjusted to indicate the dies remaining after the transfer. (end of abstract) Agent: Applied Materials/blakely - Sunnyvale, CA, US Inventor: Horne Loong Koh USPTO Applicaton #: 20080071413 - Class: 700115000 (USPTO) Related Patent Categories: Data Processing: Generic Control Systems Or Specific Applications, Specific Application, Apparatus Or Process, Product Assembly Or Manufacturing, Product Tracking (e.g., Having Product Or Carrier Identification) The Patent Description & Claims data below is from USPTO Patent Application 20080071413. Brief Patent Description - Full Patent Description - Patent Application Claims
RELATED APPLICATION [0001] This application is a continuation of U.S. patent application Ser. No. 11/247,196, now U.S. Pat. No. ______, filed Oct. 12, 2005, which claims the benefit of U.S. Provisional Application No. 60/618,805, filed Oct. 15, 2004, which is incorporated herein by reference. FIELD OF THE INVENTION [0002] Embodiments of the present invention generally relate to systems and methods for tracing die units during material transfer from, for example, one factory or lot of a semiconductor assembly and test facility to another. BACKGROUND OF THE INVENTION [0003] In semiconductor chip manufacturing processes, multiple dies (also known as die units) are fabricated on a single wafer. These dies are later separated and packaged into individual chips. The yield of chips from each wafer is not 100% because of defects during the manufacturing process. The number of good die obtained from a wafer determines the yield. Die units are typically transferred from one facility to another, or lot to lot, for various manufacturing and quality control operations. [0004] In order to keep track of the dies, each die unit on a wafer is assigned a unique identifier (Die ID), and each wafer is assigned to a grouping of wafers such as a lot. Wafers in a lot are sometimes tracked as Materials of the lot. Lot and Material objects in the Manufacturing Execution System (MES) are a representation of the physical items in the factory. The die IDs can be of any format and one convention is to use the coordinate position of the dies on the wafer as an identifier (or part of a die's identifier) where the die IDs can (but do not necessarily) contain information regarding the lot that the IDs are in. Any additional information corresponding to the dies are assigned into Additional Strings, which together with the combined Die IDs constitute the die information of the Lot or other Material. For example, users may want to add information such as product, grade, etc. to each die in the lot. Such information can be carried in the Additional strings. When the corresponding elements of the Die ID are matched with the Additional String, the information of the individual die, i.e. its ID and, say, its product can be obtained. [0005] When there is a transfer of at least some of the die units from one lot to another, the corresponding die information along with its wafer and lot information needs to be passed to the new lot. This die information is useful in tracing, at the die unit level, an individual die's history in terms of operation undergone, carrier used for its transportation, the lot it belonged to at various times, and other historical information. [0006] In a conventional assembly operation, die units may be drawn for processing from, for example, a first wafer within a first lot. Alternatively, die units can be drawn from multiple locations. Co-mingling good dies from various locations of a single wafer, from several wafers, and from several wafer lots is what typically occurs during the assembly operation. Unfortunately, whenever die units among multiple wafers and multiple lots are co-mingled, traceability as to a particular die unit is lost. If a die later proves unreliable in the field, it would be beneficial from the viewpoint of the manufacturer to identify the source of the die unit. It would also be desirable to determine how and when the die unit was manufactured. Such indicia could aid the manufacturer in improving the manufacturing process not only after the die units are shipped, but also possibly during tests of the die units before shipment. [0007] Conventional techniques used to trace die units are primarily limited to manipulating die IDs when die units are transferred from one lot to another. Due to the large amount of information often involved and the complexity of this task, this manipulation can be a slow and burdensome process. It would thus be desirous to avoid the cumbersome process of adjusting the die IDs of both the transferred die units in the receiving object, and adjusting the die IDs of the die units remaining in the source object. Accordingly, the present invention is directed to these, as well as other important ends. SUMMARY OF THE INVENTION [0008] The present invention provides a novel method, system and computer program product for tracing die units during material transfer from, for example, one factory or lot to another and efficiently maintain correspondence between die data and an individual die during, e.g., a lot transfer process. One or more embodiments of the present invention are intended to improve the mechanism of die-level traceability by assigning individual die IDs to each die unit, e.g., each lot, and associating a range of die IDs with a corresponding index string. The die IDs may include wafer ID, X-coordinate, and Y-coordinate, and can include other die-related information. The die information of a lot or material object comprises the die IDs and Additional Strings. When, for example, some dies are transferred from, e.g., a first lot to a second lot, the entire die information associated with the first lot is copied to the second lot, and a different index string is assigned to the second lot to indicate the actual dies or ranges of dies that have been transferred. The first lot's index string is then adjusted to indicate the dies remaining in the first lot after the transfer. By using the index string, the dies in a particular lot can more efficiently be kept track of without the need to manipulate and/or selectively associate individual die IDs with differing lots (and the dies therein) in the course of, e.g., transferring selected dies from the first lot to the second lot. [0009] Accordingly, the present invention relates to a method for tracing die units during manufacturing operations, which include the operative steps of assigning a first index string to a plurality of die strings that are in one-to-one correspondence to a plurality of die units, wherein the plurality of die units is associated with a source object, wherein each range of indices encompassed by the first index string identifies one of said plurality of die strings, upon transferring at least some of the die units from the source object to a receiving object, copying the plurality of die strings associated with the plurality of die units from the source object to a receiving object, assigning a second index string to the die strings associated with the die units transferred from the source object to the receiving object to indicate die units transferred to the receiving object, and adjusting the first index string in the source object to indicate die units remaining in the source object. More specifically, the die strings include wafer ID and die coordinates, each die coordinates includes an X-coordinate and Y-coordinate, the die strings include wafer ID and a range of number sequence, and the method die strings are generated from a die map of the source object. In one example, the source object is a plurality of wafers and the receiving object is a plurality of lead frames. In another example, the source object is a first plurality of lead frames and the receiving object is a second plurality of magazines. [0010] In an example of the present invention, the method for tracing die units during manufacturing operations further includes the operative steps of assigning a plurality of user-defined strings in one-to-one correspondence to said plurality of die strings. [0011] In another example of the present invention, the method for tracing die units during manufacturing operations further includes the operative steps of assigning a die picking order in one-to-one correspondence to said plurality of die string. [0012] In yet another example of the present invention, the method for tracing die units during manufacturing operations further includes the operative steps of storing said index strings and die strings associated with the die units transferred from the source object to the receiving object, wherein the stored index strings and die strings trace the history of the die units, and generating a report comprising die unit trace information. [0013] In one or more embodiments, the present invention relates to a system for tracing die units during manufacturing operations, which includes a processor to assign a first index string to a uniquely assigned plurality of die strings in one-to-one correspondence to a plurality of die units, wherein said plurality of die units is associated with a source object, wherein each indice within the first index string identifies one of said plurality of die strings, a tracking mechanism to track at least some die units transferred from the source object to a receiving object, wherein said tracking mechanism copies at least some die strings associated with the die units transferred from the source object to the receiving object, assigns a second index string to the die strings associated with the die units transferred from the source object to the receiving object and adjusts the first index string in the source object to indicate die units remaining in the source object. [0014] In one example, the system according to present invention further comprises a die bonder device for generating die strings from a die map of the source object. [0015] In another example, the system according to present invention further comprises a die history table for storing index strings and die strings associated with the die units transferred from the source object to the receiving object. [0016] In another embodiment, the present invention relates to a system for tracing die units during manufacturing operations, which includes means for assigning a first index string to a uniquely assigned plurality of die strings in one-to-one correspondence to a plurality of die units, wherein said plurality of die units is associated with a source object, wherein each range of indices encompassed by the first index string identifies one of said plurality of die strings, means for, upon transferring at least some of the die units from the source object to a receiving object, copying the plurality of die strings associated with the plurality of die units from the source object to a receiving object, means for assigning a second index string to the die strings associated with the die units transferred from the source object to the receiving object to indicate die units transferred to the receiving object, and means for adjusting the first index string in the source object to indicate die units remaining in the source object. More specifically, the die strings include wafer ID and die coordinates, wherein the die strings are generated from a die map of the source object, and wherein the die coordinates include X-coordinate and Y-coordinate. In one example, the die strings include wafer ID and a range of number sequence. In one example of the system according to present invention, the source object is a plurality of wafers and the receiving object is a plurality of lead frames. In another example, the source object is a plurality of lead frames and the receiving object is a plurality of magazines. [0017] In one example, the system according to present invention further comprises means for assigning a plurality of user-defined strings in one-to-one correspondence to said plurality of die strings. [0018] In another example, the system according to present invention further comprises means for assigning a die picking order in one-to-one correspondence to said plurality of die string. [0019] In yet another example, the system according to present invention further comprises means for storing said index strings and die strings associated with the die units transferred from the source object to the receiving object. [0020] An example of the present invention is also directed to a computer program product residing on a computer readable medium, the computer program product comprising instructions for causing a computer to assign a first index string to a uniquely assigned plurality of die strings in one-to-one correspondence to a plurality of die units, wherein said plurality of die units is associated with a source object, wherein each range of indices encompassed by the first index string identifies one of said plurality of die strings, upon transferring at least some of the die units from the source object to a receiving object, copy the plurality of die strings associated with the plurality of die units from the source object to a receiving object, assign a second index string to the die strings associated with the die units transferred from the source object to the receiving object to indicate die units transferred to the receiving object, and adjust the first index string in the source object to indicate die units remaining in the source object. 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