THREE-DIMENSIONAL MEMORY DEVICE INCLUDING TRENCH BRIDGES AND METHODS OF FORMING THE SAME

A three-dimensional memory device includes layer stacks each of which includes a first-tier alternating stack of first insulating layers and first electrically conductive layers and a second-tier alternating stack of second insulating layers and second electrically conductive layers separated by a backside trench. Memory opening fill structures vertically extend through a respective layer stack, and includes a respective vertical stack of memory elements and a respective vertical semiconductor channel. In one embodiment, a bridge structure spans an entire width of the backside trench such that a top surface of the bridge structure is located below a top surface of the second-tier alternating stack, and a bottom surface of the bridge structure is located above a bottom surface of the first-tier alternating stack. In another embodiment, a perforated bridge structure includes a plurality of vertically-extending openings.