The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 22, 2005
Filed:
May. 12, 2000
Mikio Tanaka, Tokyo, JP;
Masaaki Sugimoto, Tokyo, JP;
Takehiko Hamada, Tokyo, JP;
NEC Electronics Corporation, Kanagawa, JP;
Abstract
In failure analysis method of a semiconductor memory device, an absolute value of a position difference between two fail bits of a two-dimensional bit map is calculated while a histogram corresponding to the absolute value of the position difference is updated. The bit map indicates a map of fail bits and each fail bit corresponds to a fail memory cell. The above calculation is repeated to all combinations of two of the fail bits in the bit map. Then, an expectation function value is calculated for each of values from the histograms and the number of the fail bits. Finally, whether the fail bits has regularity or irregularity for each value is determined based on the calculated expectation function value for the value.