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US 9,449,713 B2Granted
Method for preconditioning thin film storage array for data retention
AssigneeFreescale Semiconductor, Inc.
InventorsHoracio P. Gasquet, Brian A. Winstead
Life of this patent
Estimating the term…
Abstract
A method includes over-programming thin film storage (TFS) memory cells on a semiconductor wafer with a first voltage that is higher than a highest voltage used to program the memory cells during normal operation of the memory cells. With the memory cells in an over-programmed state, the wafer is exposed to a first temperature above a product specification temperature for a period of time sufficient to induce redistribution of charge among storage elements in the memory cells.
Claims20
A method comprising:
- over-programming thin film storage (TFS) non-volatile memory cells having a plurality of nanocrystals on a semiconductor wafer with a first voltage that is higher than a highest voltage used to program the TFS non-volatile memory cells during normal operation of the memory cells, wherein over-programming includes additional electron accumulation in the plurality of nanocrystals such that the TFS non-volatile memory cells have a higher threshold voltage than would be if normal programming was performed;
- and
- before singulating the semiconductor wafer into individual die and with the TFS non-volatile memory cells in an over-programmed state, exposing the semiconductor wafer to a first temperature above a product specification temperature for a period of time sufficient to induce redistribution of charge among storage elements in the TFS non-volatile memory cells.
A method comprising:
- over-programming charge storage elements having a plurality nanocrystals in non-volatile memory cells on a semiconductor wafer at a first voltage and a first time duration, the over-programming to accumulate additional electrons in the plurality of nanocrystals such that the non-volatile memory cells have a higher threshold voltage than would be if normal programming was performed, and wherein the first voltage is greater than a maximum voltage that is specified to program the charge storage elements during normal operation and the first time duration is greater than a maximum time that is specified to program the charge storage elements during normal operation;
- and
- after the over-programming, exposing the semiconductor wafer to an elevated temperature for a second time duration, wherein the elevated temperature is at least as high as a maximum operating temperature for die on the semiconductor wafer.
Dependencies are inferred from the claim text.