Method and device for programming an electrically programmable non-volatile semiconductor memory
First Claim
1. A method of programming an electrically programmable memory, comprising:
- applying at least one first programming pulse to a group of memory cells of an electrically programmable memory;
accessing the memory cells of the group to ascertain a programming state thereof; and
applying at least one second programming pulse to those memory cells in the group whose programming state is not ascertained to correspond to a desired programming state, varying a voltage applied to a control electrode of the memory cells between the at least one first programming pulse and the at least one second programming pulse, wherein the varying the control electrode voltage comprises;
forecasting a change in biasing conditions of the memory cells in the group between the at least one first and at least one second programming pulses; and
varying the control electrode voltage according to the forecasted change in biasing conditions.
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Abstract
A device and method for programming an electrically programmable memory applies at least one first programming pulse to a group of memory cells (MC1–MCk) of the memory, accesses the memory cells of the group to ascertain a programming state thereof, and applies at least one second programming pulse to those memory cells in the group whose programming state is not ascertained to correspond to a desired programming state. A voltage applied to a control electrode of the memory cells is varied between the at least one first programming pulse and the at least one second programming pulse according to a forecasted change in biasing conditions of the memory cells in the group between said at least one first and at least one second programming pulses. Undesired over-programming of the memory cells is thus avoided.
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Citations
12 Claims
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1. A method of programming an electrically programmable memory, comprising:
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applying at least one first programming pulse to a group of memory cells of an electrically programmable memory; accessing the memory cells of the group to ascertain a programming state thereof; and applying at least one second programming pulse to those memory cells in the group whose programming state is not ascertained to correspond to a desired programming state, varying a voltage applied to a control electrode of the memory cells between the at least one first programming pulse and the at least one second programming pulse, wherein the varying the control electrode voltage comprises; forecasting a change in biasing conditions of the memory cells in the group between the at least one first and at least one second programming pulses; and varying the control electrode voltage according to the forecasted change in biasing conditions. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A circuit for programming memory cells of an electrically programmable memory, comprising:
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a circuit for applying programming pulses to selected groups of memory cells of an electrically programmable memory; a variable voltage generator for supplying a variable programming voltage to a control electrode of the memory cells in the group; and a program verify circuit for accessing the memory cells in the group, ascertaining a programming state thereof and causing programming pulses to be repeatedly applied to the memory cells in the group until the programming state thereof is not ascertained to correspond to a desired programming state, varying the control electrode voltage;
wherein it comprisesmeans for forecasting a change in memory cell bias conditions between successive programming pulses and for causing the variable voltage generator to generate a voltage depending on the forecasted change in memory cell bias conditions. - View Dependent Claims (9, 10, 11, 12)
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Specification