Three-dimensional memory device having integrated support and contact structures and method of making thereof

A three-dimensional memory device comprising:

• an alternating stack of insulating layers and electrically conductive layers located over a substrate;
• memory stack structures extending through the alternating stack, wherein each of the memory stack structures comprises a memory film and a vertical semiconductor channel contacting an inner sidewall of the memory film;
• and
• at least one integrated support and contact structure, wherein each of the at least one integrated support and contact structure includes:
• a contact via structure contacting a top surface of a respective one of the electrically conductive layers;
• a tubular dielectric liner that laterally surrounds the contact via structure;
• and
• a fin-containing dielectric pillar underlying the respective contact via structure and including a respective dielectric fin that laterally protrudes outward at each level of one or more underlying insulating layers that underlies a horizontal plane including a bottom surface of the contact via structure.