An improved Flash memory device with a distributed erase block management (EBM)
scheme is detailed that enhances operation and helps minimize write fatigue of
the floating gate memory cells of the Flash memory device. In the prior art, erase
block management of a Flash memory device, which provides logical sector to physical
sector mapping and provides a virtual rewriteable interface for the host, requires
that erase block management data be kept in specialized EBM data tables to keep
the state of the Flash memory device in case of loss of power. This placement of
EBM data in a separate erase block location from the user data slows the Flash
memory operation by requiring up to two writes and/or block erasures for every
update of the user data. Additionally, one of the goals of the EBM control is to
minimize write fatigue of the non-volatile floating gate memory cells of the Flash
memory device erase blocks by re-mapping and distributing heavily rewritten user
data sectors in a process called load leveling so that no one erase block gets
overused too quickly and reduce the expected lifespan of the Flash memory device.
The EBM data structures, however, are some of the most heavily rewritten non-volatile
floating gate memory cells in the device and thus, while helping to reduce write
fatigue in the Flash memory device, are some of the data structures most susceptible
to the process of fatigue. The Flash memory device of the invention combines the
EBM data in a user data erase block by placing it in an EBM data field of the control
data section of the erase block sectors. Therefore distributing the EBM data within
the Flash memory erase block structure. This allows the Flash memory to update
and/or erase the user data and the EBM data in a single operation, to reduce overhead
and speed operation. The Flash memory also reduces the process of EBM data structure
write fatigue by allowing the EBM data fields to be load leveled by rotating them
with the erase blocks they describe.