Excellent Synapse Characteristics of 50 nm Vertical Transistor with WOx channel for High Density Neuromorphic system

We report a WO
x
based vertical synapse transistor (ST) with excellent device characteristics such as small device area (4F
²
), large conductance range (> 10
⁵
), good retention (~ 8 hours) and excellent weight update property. With scaling the device dimension down to 50 nm, significant improvement (>10
³
) of switching speed was obtained. To further scale down the device area (2F
²
) and store G
⁺
/G
^-
weights, two ST were vertically stacked. We have confirmed that weight update can be maintained without disturbing neighbor cell.