Abstract:
An apparatus and method for tracking data for individual integrated circuits through the manufacturing process is described by programming an individual part identifier into a non-volatile portion of the integrated circuit and maintaining a database of all manufacturing step statistics for later review and analysis. The part identifier allows individual integrated circuits to be moved through the manufacturing process without the need to physically track original fabrication lots. The database of information is used to improve the manufacturing process by identifying failure trends based upon process variations.

Description:
FIELD OF THE INVENTION 
     This invention relates to integrated circuits, and more particularly to a system and method for tracking integrated circuit parts through the manufacturing process. 
     BACKGROUND OF THE INVENTION 
     In the manufacturing of integrated circuit parts (“IC parts”), a wafer consists of several hundred die. A set of wafers is grouped together and called “lots”. At each step of manufacturing, a lot is processed and the resulting data about the lot can be stored in a database. Ideally, lots proceed through the manufacturing process together so that the database of information can be useful in analyzing problems or defects in specific lots. 
     Unfortunately, in the real world, wafers can get separated from their lots and placed in new lots. During some steps, lots can be subdivided or combined into larger lots. Since lots do not remain static, it is a very tedious procedure to reconstruct all information gathered about a particular lot of wafers. In addition, with the movement of wafers among lots, the integrity of the lot data is jeopardized since the data for a lot may be inaccurate or incomplete. 
     Providing a method or system for tracking IC parts individually, regardless of their movement among various lots would produce a more accurate, detailed, and useful database. 
     Such a system would enable the entire manufacturing process to become much more productive with respect to the use of equipment and personnel by IC parts being allowed to flow through processes without trying to keep the original lots grouped in a meaningful order. Trying to keep lots grouped for the purpose of data analysis can waste much time. The lots go through different steps and get split up based on performance, causing the lots to continually decrease in size. Because it is a much more beneficial use of assets to work with large quantities of parts than many small groups, it is advantageous to move IC parts with no regard to their original lots. A system which would allow free movement of IC parts while retaining the ability for data analysis would make the manufacturing of IC parts more efficient. 
     SUMMARY OF THE INVENTION 
     The present invention solves the above-mentioned problems in the art and other problems which will be understood by those skilled in the art upon reading and understanding the present specification. The present invention provides an apparatus and method for tracking data for individual integrated circuits through the manufacturing process by programming an individual part identifier into a non-volatile portion of the integrated circuit and maintaining a database of all manufacturing step statistics for later review and analysis. Typical uses for this data is in the review of the process steps used in producing particular lots of wafers of memory chips and tracking failure rates according to lot and wafers numbers. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings, where like numerals refer to like components throughout the several views, 
     FIG. 1 is a block diagram of a computer system connected to a IC parts processor; 
     FIG. 2 is a block diagram of an IC part; 
     FIG. 3 is a flowchart of the method of the IC parts data summary; 
     FIG. 4 is a flowchart of an alternate method of gathering and tracking statistics for IC parts,; and 
     FIG. 5 is a flowchart of a method for gathering, tracking and using statistics for IC parts. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following Detailed Description, reference is made to the accompanying drawings which form a part hereof and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice and to use the invention, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the spirit and scope of the present invention. The following Detailed Description is, therefore, not to be taken in a limiting sense and the scope of the invention is defined by the appended claims. In the figures, elements having the same number perform essentially the same functions. 
     A computer system  100  as shown in FIG. 1 has a central processing unit (“CPU”)  105  and a memory  110 . Computer system  100  is coupled to a integrated circuit parts processor  115  by data bus  120 . Computer system  100  can be a Sun workstation, available from Sun Microsystems of Palo Alto, Calif., or another general purpose computer. Memory  110  can be RAM, a disk or floptical drive, or another form of primary or secondary computer storage. Data bus  120  can be a serial or parallel cable, any time of computer network, or other data transfer mode. IC parts processor  115  can be any fabrication, probe or test machine used in the manufacturing or testing of semiconductors. 
     FIG. 2 is an integrated circuit part  200 . IC part  200  can be a memory device such as a DRAM. A plurality of IC parts  200  can be combined and used to form memory modules. Such a memory module can be a Dual In-Line Memory Module (“DIMM”), a Single In-Line Memory Module (“SIMM”), or a Multi-Chip Module (“MCM”), or other such uses. In the alternative, IC part  200  can be used in a computer system for SRAM caching, various types of FLASH memory, SSRAM, PROM, EEPROM, etc. 
     Whatever the type of IC part  200 , it contains a memory array  205  as well as a plurality of nonvolatile memory elements  210 . These nonvolatile memory elements  210  may be antifuses, laser fuses, electrical fuses, FLASH memory cells, FERAM memory cells, or any other type of nonvolatile memory cell. Such nonvolatile memory elements  210  are well known in the semiconductor processing industry. 
     The nonvolatile memory elements  210  of IC part  200  can be used to store data relating specifically to the individual IC part  200 . For example, such use of the nonvolatile memory elements  210  is described in “A STRUCTURE AND A METHOD FOR STORING INFORMATION IN A SEMICONDUCTOR DEVICE,” by Zheng et al. U.S. patent application Ser. No. 08/664,109, now U.S. pat. No. 5,895,962, as well as “METHOD AND APPARATUS FOR STORAGE OF TEST RESULTS WITHIN AN INTEGRATED CIRCUIT,” by Debenham et al., U.S. patent application Ser. No. 08/591,238, now abandoned the details of which are incorporated by reference. 
     There are many uses for storing data relating to the individual IC part  200  in its nonvolatile memory elements  210 . As is discussed by Debenham et al., after an IC part  200  is tested, one of the nonvolatile memory elements  210  can be used to indicate completion of the test. In this manner, the nonvolatile memory elements  210  can be read to verify that IC part  200  has indeed completed a previous test before proceeding to a subsequent test. 
     Instead of storing test results directly on IC part  200 , the present invention uses the nonvolatile memory elements  210  to store a part identifier on each IC part  200 . The part identifier is retrieved from IC part  200  during the various processing steps of fabricating, probing, and testing the IC part  200 . Results from the processing steps can be stored in a computer database. By using a part identifier specific to individual IC parts, the present invention can reconstruct data summaries of like IC parts in any step that manufacturing that has access to these identifiers. 
     The flowchart of the method of the present invention is shown in FIG.  3 . For illustrative purposes, FIG. 3 describes the invention as implemented on a IC parts tester, which corresponds to IC Parts Processor  115  shown in FIG.  1 . The invention can also be implemented on any other IC parts processor used throughout the fabrication, probing, and testing steps. 
     In the method shown by the flowchart, a plurality of IC parts  200  are loaded on the tester at step  305  of FIG.  3 . The tester reads the part identifiers at step  310  from each of the loaded IC parts  200 . Testing proceeds at step  315  and data from the testing is collected and stored in a computer database in the memory  110  of computer system  100 . If there are more IC parts  200  that need testing, then the procedure repeats at step  325 . Again, this method of tracking data for individual IC parts  200 , as shown in FIG. 3, can be implemented on all of the machines used throughout the manufacturing process. 
     Once a database is generated by the fabrication, testing, and probing of IC parts  200  by the various IC parts processors  115 , computer system  100  can be used to analyze and report data specific to individual IC parts  200 . The database stored in computer system  100  can be sorted to reconstruct data summaries of parts that all began manufacturing together, or that have other similar characteristics. 
     In another embodiment, the data may be fed to the computer processor  100  from parts processor  115  in real time, as shown in FIG.  4 . The process shown in FIG. 4 is identical to the process shown in FIG. 3 except for the sending of data to the computer  100  at step  320  is performed for each IC processed. 
     Also shown in FIG. 4 are the steps for associating the data with the part identifiers. This association, performed by computer  100 , may be used to gather and track statistics based on lot, wafer or individual parts. The statistics may show, by way of example and not by way of limitation, trends in failures of parts of a particular lot, types of failures in processing of wafers based on process variations, etc. Those skilled in the art will readily recognize that a wide variety of information may be tracked and associated with each integrated circuit or memory device without being limited to the size of the non-volatile memory on the individual circuits. 
     CONCLUSION 
     Although specific embodiments have been illustrated and described wherein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown. This patent is intended to cover any adaptations or variations of the present invention. Therefore, it is manifestly intended that this invention be limited only by the claims and the equivalents thereof.