Static information storage and retrieval – Read/write circuit – Data refresh
Reexamination Certificate
2006-01-30
2008-11-11
Elms, Richard (Department: 2824)
Static information storage and retrieval
Read/write circuit
Data refresh
C365S200000, C365S201000
Reexamination Certificate
active
07450458
ABSTRACT:
The present invention enables screening of the so-called variable retention time (VRT) failure, namely a retention failure occurring in a DRAM due to fluctuation of a data retention time like a random telegraph noise. A pause/refresh test for checking a data retention function is repeated at all memory cells of a chip so that memory cells at which the retention failure due to random fluctuation of the data retention capability over time may occur is subjected to screening.
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P.J. Restle et al., “DRAM Variable Retention Time”, I.E.D.M. Technology Digest (1992), pp. 807-810.
D.S. Yaney et al., “A Meta-Stable Leakage Phenomenon in DRAM charge Storage—Variable Hold Time”, I.E.D.M. Technology Digest (1987), pp. 336-339.
Mori Yuki
Oyu Kiyonori
Tsukada Shuichi
Yamada Renichi
A. Marquez, Esq. Juan Carlos
Elms Richard
Elpida Memory Inc.
Fisher Esq. Stanley P.
Hitachi , Ltd.
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