Data writing method for flash memory, and flash memory controller and storage device thereof

A flash memory controller suitable for a storage device with a multi level cell NAND flash memory, wherein a block of the multi level cell NAND flash memory comprises a plurality of upper page addresses and a plurality of lower page addresses respectively corresponding to the upper page addresses at which a writing speed is higher than that at the upper addresses, the flash memory controller comprising:

• a microprocessor unit;
• a flash memory interface for accessing to the multi level cell NAND flash memory;
• a buffer for temporarily storing data;
• and
• a memory management module for receiving a writing command and new data corresponding to the writing command, determining whether an address to be written with the new data is one of the upper page addresses, continuously copying a plurality of old data from a first lower page address and at least one second lower page address as old data backups only when the address to be written with new data is one of the upper page addresses, and writing the new data to the address to be written,
• wherein the first lower page address corresponds to the address to be written and the at least one second lower page address is located between the address to be written and the first lower page address.

A flash memory storage device, comprising:

• a bus interface, for connecting to a host;
• a multi level cell NAND flash memory, for storing data, wherein a block the multi level cell NAND flash memory comprises a plurality of upper page addresses and a plurality of lower page addresses respectively corresponding to the upper page addresses at which a writing speed is higher than that at the upper addresses;
• and
• a controller, electrically connected to the bus interface and the multi level cell NAND flash memory for suitable for receiving a writing command and new data corresponding to the writing command, determining whether an address to be written with the new data is one of the upper page addresses, continuously copying a plurality of old data from a first lower page address and at least one second lower page address as old data backups only when the address to be written with new data is one of the upper page addresses, and writing the new data to the address to be written,
• wherein the first lower page address corresponds to the address to be written and the at least one second lower page address addresses is located between the address to be written and the first lower page address corresponding to the address to be written.