This node is expected to be ready for volume production in late 2021 and will likely be on the market at the same time as Intel's 7nm. The 3nm process from Samsung will use a gate-all-around (GAA) transistor design it calls Multi-Bridge Channel Field Effect Transistor (MBCFET). Instead of the nanowires used by GAAFETs, the Samsung design will use nanosheets to simplify production.
Tom's Hardware writer witeken points out on Twitter that Intel promises a 20 percent improvement in performance per Watt for 7nm, but speculates Intel's 7nm may actually have a slightly better transistor density than Samsung's 3nm node.
Based on the timing of volume production, Samsung's 3nm process (3GAE) will compete with Intel's 7nm. The name seems to imply a two node advantage for Samsung, but I wouldn't be surprised if Intel 7nm actually has (slightly) higher transistor density.— witeken (@witeken) 15 mei 2019
The first customer tape-outs on 3nm are expected in 2020. Samsung claims designs made for its upcoming 4nm will easily migrate to 3nm.