What is claimed is:1. A three-dimensional memory device, comprising:a pair of alternating stacks of insulating layers and electrically conductive layers laterally spaced apart from each other by a backside trench, wherein each of the pair of alternating stacks and the backside trench laterally extend along a first horizontal direction;arrays of memory openings vertically extending through a respective alternating stack among the pair of alternating stacks;arrays of memory openings fill structures located in the arrays of memory openings, wherein each of the memory opening fill structures comprises a respective vertical stack of memory elements; anda backside trench fill structure located within the backside trench and comprising a plurality of bridge structures;wherein each of the plurality of bridge structures includes a doped semiconductor material; andwherein each of the plurality of bridge structures is embedded within a respective dielectric semiconductor oxide liner which comprises a dielectric oxide of the doped semiconductor material.2. The three-dimensional memory device of claim 1, wherein the plurality of bridge structures comprises:a first bridge structure located at a first vertical distance from a horizontal plane including a top surface of the substrate; anda second bridge structure located at a second vertical distance from the horizontal plane, wherein the second vertical distance is different from the first vertical distance.3. The three-dimensional memory device of claim 2, wherein the second bridge structure is laterally offset from the first bridge structure along the first horizontal direction.4. The three-dimensional memory device of claim 2, wherein the second bridge structure does not have any areal overlap with the first bridge structure in a plan view along a vertical direction that is perpendicular to a top surface of the substrate.5. The three-dimensional memory device of claim 1, wherein:the first bridge structure is located above a horizontal plane including topmost surfaces of the pair of alternating stacks; andthe second bridge structure is located below the horizontal plane including the topmost surfaces of the pair of alternating stacks.6. The three-dimensional memory device of claim 5, further comprising a pair of contact-level dielectric material portions located above a respective alternating stack within the pair of alternating stacks, wherein the first bridge structure has a top surface located within a horizontal plane including top surfaces of the pair of contact-level dielectric material portions.7. The three-dimensional memory device of claim 1, wherein the doped semiconductor material comprises boron doped silicon.8. The three-dimensional memory device of claim 1, wherein the plurality of bridge structures comprises three bridge structures located at three different vertical distances from a horizontal plane including a top surface of the substrate.9. The three-dimensional memory device of claim 1, wherein the backside trench fill structure comprises an insulating backside trench fill material portion embedding each bridge structure of the plurality of bridge structures.10. The three-dimensional memory device of claim 9, wherein:the backside trench fill structure contacts a respective sidewall of each layer within the pair of alternating stacks; andsidewalls of the insulating backside trench fill material portion contacts a pair of lengthwise sidewalls of the backside trench that laterally extends along the first horizontal direction.11. The three-dimensional memory device of claim 1, wherein the plurality of bridge structures comprises:a row of first bridge structures that are arranged along the first horizontal direction and located at a first vertical distance from a horizontal plane including a top surface of the substrate; anda row of second bridge structures that are arranged along the first horizontal direction and located at a second vertical distance from the horizontal plane, wherein the second vertical distance is different from the first vertical distance.
