Three-dimensional memory device including locally thickened electrically conductive layers and methods of manufacturing the same

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;
• and
• a staircase region including stepped surfaces of the alternating stack, wherein the electrically conductive layers have lateral extents that decrease with a vertical distance from the substrate within the staircase region,
• wherein at least one of the electrically conductive layers has a first thickness in a first area that underlies an overlying one of the insulating layers of the alternating stack, a second thickness in a distal segment of a second area that laterally protrudes farther than the overlying one of the insulating layers of the alternating stack, and a third thickness in a proximal segment of the second area located between the distal segment of the second area and the first area, wherein the second thickness is greater than the first thickness, and the third thickness is different from the second thickness.