Three-dimensional memory device with word line side-contact via structures and methods for forming the same

A method of forming a memory device, comprising:

• forming at least one alternating stack of insulating layers and sacrificial material layers over a substrate;
• forming memory openings through the at least one alternating stack;
• forming memory opening fill structures in the memory openings, wherein each of the memory opening fill structures comprises a respective vertical stack of memory elements;
• forming a combination of a contact opening and a vertical stack of annular dielectric spacers through the at least one alternating stack, wherein the vertical stack of annular dielectric spacers comprises an annular sacrificial spacer located adjacent to a first one of the sacrificial material layers, at least one upper annular dielectric spacer overlying the annular sacrificial spacer, and at least one lower annular dielectric spacer underlying the annular sacrificial spacer;
• replacing the sacrificial material layers with electrically conductive layers;
• removing the annular sacrificial spacer and inner portions of the annular dielectric spacers around the contact opening, wherein a cylindrical sidewall of a first electrically conductive layer is physically exposed in the contact opening;
• and
• forming a side-contact via structure in the contact opening in contact with the cylindrical sidewall of the first electrically conductive layer, wherein the side-contact via structure is laterally spaced from and is electrically isolated from a remainder of the electrically conductive layers other than the first electrically conductive layer by remaining portions of the vertical stack of annular dielectric spacers.