Suppressing Channel Percolation in Ferroelectric FET for Reliable Neuromorphic Applications.

Channel percolation in ferroelectric FET (FeFET) due to random spatial distribution of switched domains reduces the number of accessible threshold voltage (V-TH) states, thus posing a profound reliability challenge when it comes to its usage as synaptic weight cell in neuromorphic applications. However, channel percolation is not universally present in FeFET and only exists when the channel regions underneath the domains have negligible interaction, e.g., when the domain is large enough. In this work, we performed a comprehensive evaluation on the parameters that could impact neighbor interaction, and hence channel percolation. We reveal that: i) weak gate control with thick ferroelectric (FE) layer enhances neighbor interaction and suppresses channel percolation; ii) higher temperature can also reduce percolation by weakening the gate control. These insights provide an important guideline for to engineer more reliable FeFET analog states.