Bitstream defect analysis method for integrated circuits
First Claim
1. A method of controlling the fabrication of multiple integrated circuit (IC) dice fabricated on respective IC wafers, with each wafer having multiple dice, comprising:
- fabricating an IC wafer having multiple IC dice located at predetermined positions on the wafer,testing the IC dice on said IC wafer for defects in a sequence that corresponds to the positions of said dice on the wafer,encoding the results of said testing into an output signal in the form of a serial digital data bitstream with a bit sequence that corresponds to the test sequence and the positions of said dice on said wafer,operating upon the dice positional information in said data bitstream output signal to categorize defects identified in said dice by said testing, andmodifying the fabrication for subsequent wafers based upon the results of said defect categorization.
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Abstract
Defects in the manufacturing of IC devices are analyzed by testing the devices for defects, generating a serial digital data bitstream upon which the test result for each device is encoded in succession, and operating upon the data bitstream to analyze the device defects. This allows for the use of rapid and reliable digital signal processing techniques to perform the analysis. The types of analyses that can be performed include the determination of non-random yields to distinguish random from systematic defects, comparisons with signature defect patterns that correspond to various systematic faults, and yield predictions for other circuits manufactured with a similar process but having a different critical circuit area. An improved windowing technique is used to determine non-random defects, in which normalized defect counts are obtained and compared for various window sizes. Multiple functional and parametric tests for each device can be accommodated in several ways, including the assignment of additional data bits in the bitstream to the additional tests. The defect analysis can be performed in real-time on one batch while the next batch is being processed, with the results of the analysis used to correct the manufacturing process if systematic defects are identified. An improved method is also described for calculating the non-random yield loss factor Yo, which can be used in yield models for yield prediction purposes.
201 Citations
14 Claims
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1. A method of controlling the fabrication of multiple integrated circuit (IC) dice fabricated on respective IC wafers, with each wafer having multiple dice, comprising:
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fabricating an IC wafer having multiple IC dice located at predetermined positions on the wafer, testing the IC dice on said IC wafer for defects in a sequence that corresponds to the positions of said dice on the wafer, encoding the results of said testing into an output signal in the form of a serial digital data bitstream with a bit sequence that corresponds to the test sequence and the positions of said dice on said wafer, operating upon the dice positional information in said data bitstream output signal to categorize defects identified in said dice by said testing, and modifying the fabrication for subsequent wafers based upon the results of said defect categorization. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification