Apparatus and methods for controlling refresh operations
摘要
說明書
In order to solve such a problem, recently, a technique which restores the electric charge with respect to the information-retention-time-reduced memory cells by utilizing the history of access to the memory cells has been studied. This technique is called target-row refresh.
Herein, in a case in which a defective word line is replaced by a redundant word line, erroneous operations may occur unless the target-row refresh operation is carried out in consideration of that. This is for a reason that actually-used (functional) redundant word lines and unused (non-functional) redundant word lines are mixed in the redundant word lines. More specifically, when the unused redundant word line is selected in a target-row refresh operation, for example, if micro short-circuit is present at the unused redundant word line or the memory cells connected thereto, there has been a risk that other data may be broken.
