US 12,322,447 B2
Apparatus with multi-bit cell read mechanism and methods for operating the same
Matteo Impala′, Milan (IT); Mattia Robustelli, Milan (IT); and Innocenzo Tortorelli, Milan (IT)
Assigned to Micron Technology, Inc., Boise, ID (US)
Filed by Micron Technology, Inc., Boise, ID (US)
Filed on Oct. 20, 2022, as Appl. No. 17/970,315.
Prior Publication US 2024/0135996 A1, Apr. 25, 2024
Prior Publication US 2024/0233828 A9, Jul. 11, 2024
Int. Cl. G11C 16/10 (2006.01); G11C 16/26 (2006.01); G11C 16/34 (2006.01)
CPC G11C 16/102 (2013.01) [G11C 16/26 (2013.01); G11C 16/3404 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A memory device, comprising:
rewritable memory cells including multi-level cells (MLCs) that are each configured to store two bits using a set of storage states that correspond to a minimum threshold voltage (Vt), a maximum Vt, a ternary (T) state, and at least one intermediate (I) state for positive and negative polarities; and
a logic circuit operably coupled to the memory cells and configured to:
determine a polarity data associated with reading a target location amongst the MLCs;
detect a storage state at the target location based on applying a sequence of voltage levels for a first polarity and then a second polarity,
wherein the sequence of the first and second polarity is selected according to the polarity data and is configured to write over an intermediate Vt in distinguishing between the T state and the at least one I state,
wherein the storage state is detected based on adjusting a voltage application sequence to (1) first apply one or more voltage levels matching the first polarity indicated by the polarity data for enabling detection of the intermediate Vt and then (2) one or more voltage levels for the second polarity that is opposite the first polarity, and
wherein the determined polarity data indicates the first polarity representing that the target location is configured to implement the intermediate Vt using the first polarity;
control application of a reprogramming voltage along the second polarity for reestablishing the storage state, wherein the reestablished storage state corresponds to the intermediate Vt,
wherein, when the storage state of the target location corresponds to the intermediate Vt, the reprogramming voltage applied along the second polarity is configured to reestablish the intermediate Vt using the second polarity after the detection of the storage state instead of using the first polarity as was before the detection; and
update the polarity data after detecting the storage state, wherein the polarity data is changed from the first polarity to the second polarity for a subsequent read operation at the target location.