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US 6,634,004 B1Granted
Threshold analysis system capable of deciding all threshold voltages included in memory device through single processing
AssigneesMitsubishi Denki Kabushiki Kaisha, Ryoden Semiconductor System Engineering Corporation
InventorsShinji Yamada, Hisaya Mori, Teruhiko Funakura
Life of this patent
Estimating the term…
Abstract
In a threshold analysis method obtaining threshold voltages of all bits in a flash memory through single processing, fail bit map information is examined in order from a smaller voltage applied to the flash memory. As to a bit exhibiting a value, read from the flash memory, first mismatching a determination value, the threshold voltage is settled on the basis of a voltage applied when the bit fails in reading.
Claims16
A threshold analysis system including:
- a signal generation circuit generating a plurality of types of voltages and sequentially applying each of said plurality of types of voltages to a plurality of cells forming a memory device;
- an address generator sequentially generating address signals specifying the respective ones of said plurality of cells;
- a memory storing data read from said memory device as fail bit map information as to each of said plurality of types of voltages;
- and
- a threshold voltage calculation part connected to said memory for calculating threshold voltages of said plurality of cells forming said memory device from a plurality of pieces of fail bit map information corresponding to said plurality of types of voltages.
2 more elements
A threshold analysis method employed in a threshold analysis system including:
- a signal generation circuit generating a plurality of types of voltages and sequentially applying each of said plurality of types of voltages to a plurality of cells forming a memory device;
- an address generator sequentially generating address signals specifying the respective ones of said plurality of cells;
- a memory storing data read from said memory device as fail bit map information as to each of said plurality of types of voltages;
- and
- a threshold voltage calculation part connected to said memory for calculating threshold voltages of said plurality of cells forming said memory device from a plurality of pieces of fail bit map information corresponding to said plurality of types of voltages,
- said threshold analysis method including steps of:
- sequentially applying each of said plurality of types of voltages to said plurality of cells;
- sequentially generating said address signals specifying the respective ones of said plurality of cells;
- storing data read from said memory device as fail bit map information as to each of said plurality of types of voltages;
- and
- calculating threshold voltages of said plurality of cells forming said memory device from said plurality of pieces of fail bit map information stored in said memory.
8 more elements
Dependencies are inferred from the claim text.