Compensating for coupling during read operations of non-volatile memory
AssigneeSanDisk Corporation
InventorJian Chen
Life of this patent
Estimating the term…
Abstract
Shifts in the apparent charge stored on a floating gate (or other charge storing element) of a non-volatile memory cell can occur because of the coupling of an electric field based on the charge stored in adjacent floating gates (or other adjacent charge storing elements). The problem occurs most pronouncedly between sets of adjacent memory cells that have been programmed at different times. To compensate for this coupling, the read process for a given memory cell will take into account the programmed state of an adjacent memory cell.
Claims24
A method for reading non-volatile storage, comprising:
- performing a read process for a set of non-volatile storage elements using a set of one or more read compare points, said read process provides a set of read data;
- determining whether said read data has one or more errors;
- determining whether an error correction process is able to correct said one or more errors;
- correcting said one or more errors using said error correction process if said error correction process is able to correct said one or more errors;
- and
- performing a data recovery process if said error correction process is not able to correct said one or more errors, said data recovery process comprises reading non-volatile storage elements adjacent to said set of non-volatile storage elements, adjusting said one or more read compare points for at least a subset of said set of non-volatile storage elements based on reading of said non-volatile storage elements adjacent to said set of non-volatile storage elements and performing another one or more read processes for said set of non-volatile storage elements using said adjusted one or more read compare points.
A method for reading non-volatile storage, comprising:
- performing a read process for a set of non-volatile storage elements, said read process includes using a set of reference values to determine a set of read data stored in said set of non-volatile storage elements;
- determining that said read data has one or more errors that cannot be corrected by an error correction process;
- and
- performing a data recovery process for said set of non-volatile storage elements that includes using a set of offsets with said reference values to determine a corrected set of read data, said offsets are chosen on an individual basis for said set of non-volatile storage elements based on status of respective adjacent storage elements to said set of non-volatile storage elements.
Dependencies are inferred from the claim text.