Three-dimensional memory devices and methods for forming the same

A three-dimensional (3D) memory device, comprising:

• a plurality of contacts aligned in a row in a first direction on a staircase;
• a plurality of groups of support structures aligned in a plurality of rows in the first direction;
• and
• a fourth support structure between adjacent groups of support structures, wherein:
• the row of the contacts and the plurality of rows of the support structures are apart from one another in a second direction perpendicular to the first direction;
• each of the contacts is surrounded by a group of support structures;
• one of the groups of support structures comprises three support structures;
• and
• one of the contacts and any one of the three support structures of a respective group are on a same side of other two of the three support structures of the respective group along a direction, the direction being perpendicular to a line which the other two of the three support structures are located.

A method for forming a three-dimensional (3D) memory device, comprising:

• forming a stack structure of a plurality of first layers and a plurality of second layers;
• forming a staircase in a staircase region of the stack structure;
• forming a plurality of contacts on the staircase;
• forming a plurality of groups of support structures in the staircase;
• and
• forming a fourth support structure between adjacent groups of support structures,
• wherein the plurality of groups of support structures each comprises three support structures, projections of the three support structures forming a triangular shape in a plane parallel to a first direction, and
• the plurality of contacts each is surrounded by a respective group, a projection of one of the contacts overlapping with the triangular shape of the respective group.