As a unique mechanism for MRAMs, magnetic coupling needs to be accounted for when designing memory arrays. This paper models both intra- and inter-cell magnetic coupling analytically for STT-MRAMs and investigates their impact on the write performance and retention of the MTJ device, the data-storing element of STT-MRAMs. We present magnetic measurement data of MTJ devices with diameters ranging from 35nm to 175 nm, which we use to calibrate our intra-cell magnetic coupling model. Subsequently, we extrapolate this model to study inter-cell magnetic coupling in memory arrays. We propose the inter-cell magnetic coupling factor Psi to indicate coupling strength. Our simulations show that Psi=2% maximizes the array density under the constraint that the magnetic coupling has negligible impact on the device’s performance. Higher array densities show significant variations in average switching time, especially at low switching voltages, caused by inter-cell magnetic coupling, and dependent on the data pattern in the cell’s direct neighborhood. We also observe a marginal degradation of the data retention time under the influence of inter-cell magnetic coupling.
Original languageEnglish
Title of host publicationPreliminary Conference 2019
Number of pages6
Publication statusAccepted/In press - 1 Oct 2019
EventDATE 20: Design, Automation and Test in Europe Conference - Grenoble, France
Duration: 9 Mar 202013 Mar 2020


ConferenceDATE 20: Design, Automation and Test in Europe Conference
Abbreviated titleDATE 20
Internet address

ID: 68213547