US 8,274,838 B2Granted

Programming non-volatile memory with bit line voltage step up

AssigneeSanDisk Technologies LLC

InventorsDeepanshu Dutta, Jeffrey W. Lutze

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Abstract

Threshold voltage distributions in a non-volatile memory device are narrowed, and/or programming time is reduced, using a programming technique in which the bit line voltage for storage elements having a target data state is stepped up, in lock step with a step up in the program voltage. The step up in the bit line voltage is performed at different times in the programming pass, for different subsets of storage elements, according to their target data state. The start and stop of the step up in the bit line voltage can be set based on a fixed program pulse number, or adaptive based on a programming progress. Variations include using a fixed bit line step, a varying bit line step, a data state-dependent bit line step, an option to not step up the bit line for one or more data states and an option to add an additional bit line bias.

Claims26

Dependent claims

A method for programming a set of non-volatile storage elements, comprising:

applying a set of program pulses to the set of non-volatile storage elements, each non-volatile storage element in the set of non-volatile storage elements is associated with a respective bit line, the set of non-volatile storage elements includes different subsets of non-volatile storage elements, each subset is programmed to a respective verify level of a respective target data state among a plurality of target data states, and the set of non-volatile storage elements includes one subset of non-volatile storage elements which is programmed to one respective verify level of one respective target data state;
determining when a first trigger condition is met for the one subset of non-volatile storage elements during the set of program pulses;
and
when the first trigger condition is met, stepping up a voltage of respective bit lines of non-volatile storage elements of the one subset which have not yet been locked out from programming, in lockstep with each program pulse of a plurality of successive program pulses of the set of program pulses, the voltage is stepped up to a different level for each of the successive program pulses, and each of the different levels is below a lockout level.

1 more element

A method for programming a set of non-volatile storage elements, comprising:

applying a set of program pulses to the set of non-volatile storage elements, each non-volatile storage element in the set of non-volatile storage elements is associated with a respective bit line, the set of non-volatile storage elements includes different subsets of non-volatile storage elements, each subset is programmed to a respective verify level of a respective target data state among a plurality of target data states, and the set of non-volatile storage elements includes one subset of non-volatile storage elements which is programmed to one respective verify level of one respective target data state;
stepping up a voltage of respective bit lines of non-volatile storage elements of the one subset which have not yet been locked out from programming, in lockstep with each program pulse of a plurality of successive program pulses of the set of program pulses, the voltage is stepped up to a different level for each of the successive program pulses, and each of the different levels is below a lockout level;
determining when a trigger condition is met for the one subset of non-volatile storage elements during the set of program pulses;
and
when the trigger condition is met, fixing the voltage below the lockout level with each program pulse of one or more additional program pulses of the set of program pulses.

2 more elements

A non-volatile storage system, comprising:

a set of non-volatile storage elements, the set of non-volatile storage elements includes different subsets of non-volatile storage elements, each subset is programmed to a respective verify level of a respective target data state among a plurality of target data states, and the set of non-volatile storage elements includes one subset of non-volatile storage elements which is programmed to one respective verify level of one respective target data state;
a respective bit line associated with each non-volatile storage element;
and
at least one control circuit, the at least one control circuit:
applies a set of program pulses to the set of non-volatile storage elements, steps up a voltage of respective bit lines of non-volatile storage elements of the one subset which have not yet been locked out from programming, in lockstep with each program pulse of a plurality of successive program pulses of the set of program pulses, the voltage is stepped up to a different level for each of the successive program pulses, and each of the different levels is below a lockout level, determines when a trigger condition is met for the one subset of non-volatile storage elements during the set of program pulses, and when the trigger condition is met, fixing the voltage below the lockout level with each program pulse of one or more additional program pulses of the set of program pulses.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 12/838,902Filed 19 Jul 2010
Published: US 2012/0014184 A119 Jan 2012
Granted: 25 Sep 2012
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G11C 16/10
Auxiliary circuits, e.g. for writing into memory: programming or data input circuits
G11C 11/5628
Using charge storage in a floating gate: programming or writing circuits; Data input circuits
G11C 16/0483
Using variable threshold transistors, e.g. FAMOS: comprising cells having several storage transistors connected in series
G11C 16/24
Auxiliary circuits, e.g. for writing into memory: bit-line control circuits