An Optimal On-demand Scrubbing Solution for Read Disturbance Errors in Phase-change Memory

Phase-change memory is a promising memory technology due to its attractive properties. However, phase-change memory is difficult to be commercialized because of its reliability issues. A read disturbance error, which is the main cause of reliability issues, occurs when a cell is repeatedly read. Conventional solution for read disturbance errors is periodically scrubbing the cells. However, this method requires read counters to count the number of reads per word. This paper proposes on-demand scrubbing solution which does not need read counters. The proposed method observes the number of errors in a word using the error-correcting code. If the number of errors is larger than the threshold, a scrubbing is performed to fix the errors. The proposed method removes nearly 1GB of hardware overhead caused by read counters, and fixes more than 99.99% of read disturbance errors.