Three-dimensional memory devices with channel structures having plum blossom shape and methods for forming the same

Embodiments of three-dimensional (3D) memory devices and methods for forming the same are disclosed. In an example, a 3D memory device includes a substrate and a channel structure extending vertically above the substrate and having a plum blossom shape including a plurality of petals in a plan view. The channel structure includes, in each of the plurality of petals, a charge trapping layer, a tunneling layer, a semiconductor channel, and a channel plug. The channel plug is above and in contact with the charge trapping layer, the tunneling layer, and the semiconductor channel.