Content addressable memory using threshold-adjustable vertical transistors and methods of forming the same

A content addressable memory cell array comprising:

• a plurality of match lines disposed in parallel along a first axis;
• a plurality of ground lines disposed in parallel along the first axis;
• a plurality of search lines disposed in parallel substantially perpendicular to the first axis;
• and
• a plurality of content addressable memory elements, each content addressable memory element comprising a vertical ferroelectric transistor disposed between a corresponding one of the match lines and a corresponding one of the ground lines, and each coupled to a corresponding one of the search lines.

A monolithic three-dimensional content addressable memory cell array comprising:

• a first memory level disposed above a substrate, the first memory level comprising:
• a plurality of first match lines disposed in parallel along a first axis;
• a plurality of first ground lines disposed in parallel along the first axis and above the plurality of first match lines;
• a plurality of first search lines disposed in parallel substantially perpendicular to the first axis;
• and
• a plurality of first content addressable memory elements, each first content addressable memory element comprising a vertical ferroelectric transistor disposed between a corresponding one of the first match lines and a corresponding one of the first ground lines, and each coupled to a corresponding one of the first search lines;
• and
• a second memory level disposed above the first memory level, the second memory level comprising:
• a plurality of second match lines disposed in parallel along the first axis and above the plurality of first ground lines;
• a plurality of second search lines disposed in parallel substantially perpendicular to the first axis;
• and
• a plurality of second content addressable memory elements, each second content addressable memory element comprising a vertical ferroelectric transistor disposed between a corresponding one of the second match lines and a corresponding one of the first ground lines, and each coupled to a corresponding one of the second search lines.