Method of operating incrementally programmable non-volatile memory
First Claim
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1. A method of erasing or resetting an array of non-volatile memory cells on an integrated circuit where each of such cells in the array is adapted to store data through injection of hot carriers into a floating gate, the method comprising:
- a) for each program cycle in which said array is configured with a new data pattern;
i. providing an original target highest threshold voltage for programming the cells in said program cycle, andii. programming cells in said array selectively to store said new data pattern during said program cycle through injected electrons; and
b) performing a reset of the array prior to programming said cells in said array in a subsequent program cycle, further injecting electrons to all of the memory cells, such that the threshold voltage of every cell in the array is substantially same as the original highest threshold voltage used in a prior program cycle;
wherein said cells in said array are operated as one-time programmable (OTP) and/or multi-time programmable (MTP) cells.
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Abstract
An array of programmable non-volatile devices, such as a nominal OTP cell, is operated such that a Vt representing a particular binary logic state is changed over time. This allows for re-programming and emulating a few times or multi-time programmable device.
49 Citations
9 Claims
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1. A method of erasing or resetting an array of non-volatile memory cells on an integrated circuit where each of such cells in the array is adapted to store data through injection of hot carriers into a floating gate, the method comprising:
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a) for each program cycle in which said array is configured with a new data pattern; i. providing an original target highest threshold voltage for programming the cells in said program cycle, and ii. programming cells in said array selectively to store said new data pattern during said program cycle through injected electrons; and b) performing a reset of the array prior to programming said cells in said array in a subsequent program cycle, further injecting electrons to all of the memory cells, such that the threshold voltage of every cell in the array is substantially same as the original highest threshold voltage used in a prior program cycle; wherein said cells in said array are operated as one-time programmable (OTP) and/or multi-time programmable (MTP) cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of programming an array of non-volatile memory cells on an integrated circuit where each of such cells in the array is adapted to store data through injection of hot carriers into a floating gate, the method comprising:
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a) for each program cycle in which said array is configured with a first data pattern; i. providing a first target threshold voltage for programming the cells in said program cycle, and ii. programming cells in said array selectively to store said first data pattern during said program cycle through injected electrons; b) resetting the array by injecting electrons to all the array cells, such that the threshold voltage of every cell in the array is substantially the same as the first target threshold voltage used in an immediately prior program cycle; and c) programming cells in said array selectively to store a second data pattern during a second program cycle using injected electrons to establish a second target threshold voltage that is higher than said first target threshold voltage;
wherein otherwise nominal OTP cells are transformed into few-time or multi-time cells by altering their initial threshold levels at each programming cycle representing a particular logic state.
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Specification