Three-dimensional memory device

A 3D memory device includes a peripheral circuit, a storage stack, a semiconductor layer, a plurality of channel structures and a source contact. The storage stack is disposed above the peripheral circuit and includes alternating conductive layers and dielectric layers. The semiconductor layer is disposed above the storage stack. Each channel vertically extends through the storage stack into the semiconductor layer. Each channel structure includes a semiconductor channel, and the semiconductor layer surrounds the semiconductor channel. The semiconductor channel extends to a portion of the semiconductor layer and contacts the semiconductor layer. The source contact is located above the storage stack and contacts the semiconductor layer.