Program Control Circuit of Flash Memory Device Having MLC and Method Thereof
First Claim
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1. A program control circuit of a flash memory device including a plurality of MLCs that share word lines and bit lines, comprising:
- a controller that generates bit line masking signals and a step control signal in response to compare signals received from a verify data comparator, generates one of first to third cycle control signals and a first or second verify control signal based on the number of times that a step control signal is generated, outputs the bit line masking signals to a page buffer circuit connected to the bit lines, and outputs the step control signal to a word line voltage generator;
a clock signal generator that generates one of first to third clock signals and one of inverted first to third clock signals in response to one of the first to third cycle control signals; and
a voltage select circuit that outputs a program bias voltage, which is generated from the word line voltage generator, to a X-decoder connected to the word lines during one of first to third predetermined times or outputs a verify bias voltage, which is generated from the word line voltage generator, to the X-decoder during a fourth predetermined time, in response to one of the first to third clock signals and one of the inverted first to third clock signals, which are received from the clock signal generator.
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Abstract
A program control circuit and method thereof selectively controls a supply time of a word line bias voltage depending on the number of program cycles being in progress. Therefore, over-programming of MLCs can be prevented and an overall program time can be shortened.
37 Citations
18 Claims
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1. A program control circuit of a flash memory device including a plurality of MLCs that share word lines and bit lines, comprising:
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a controller that generates bit line masking signals and a step control signal in response to compare signals received from a verify data comparator, generates one of first to third cycle control signals and a first or second verify control signal based on the number of times that a step control signal is generated, outputs the bit line masking signals to a page buffer circuit connected to the bit lines, and outputs the step control signal to a word line voltage generator;
a clock signal generator that generates one of first to third clock signals and one of inverted first to third clock signals in response to one of the first to third cycle control signals; and
a voltage select circuit that outputs a program bias voltage, which is generated from the word line voltage generator, to a X-decoder connected to the word lines during one of first to third predetermined times or outputs a verify bias voltage, which is generated from the word line voltage generator, to the X-decoder during a fourth predetermined time, in response to one of the first to third clock signals and one of the inverted first to third clock signals, which are received from the clock signal generator. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A program control method of a flash memory device including a plurality of MLCs that shares word lines and bit lines, comprising:
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a first program to affect programming of MLCs of a selected page by applying a program voltage, which is increased by a step voltage, to a selected word line of the word lines during a first predetermined time in each of first to Ith (I is an integer) program cycles in response to a first cycle control signal;
a second program to affect programming of the MLCs of the selected page by applying a first last program voltage (i.e., a program voltage that has been finally increased in the first program step) to the selected word line, while increasing the last program voltage by a step voltage, during a second predetermined time in each of first to (I+1)th to Jth (J is an integer) program cycles in response to a second cycle control signal; and
a third program to affect programming of the MLCs of the selected page by applying a second last program voltage (i.e., a program voltage that has been finally increased in the second program step) to the selected word line, while increasing the second to last program voltage by the step voltage, during a third predetermined time in each of first to (J+1)th to Kth (K is an integer) program cycles in response to a third cycle control signal. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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Specification