Content addressable memory cells and memory arrays
A content addressable memory cell is provided that includes plurality of transistors having a minimum feature size F, and a plurality of memory elements coupled to the plurality of transistors. The content addressable memory cell occupies an area of between 18F 2 and 36F 2 .
1. A content addressable memory cell comprising:
a first vertically-oriented pillar-shaped transistor and a second vertically-oriented pillar-shaped transistor each disposed above a substrate;
a third vertically-oriented pillar-shaped transistor and a fourth vertically-oriented pillar-shaped transistor each disposed above the first vertically-oriented pillar-shaped transistor and the second vertically-oriented pillar-shaped transistor, the third vertically-oriented pillar-shaped transistor coupled to the first vertically-oriented pillar-shaped transistor, and the fourth vertically-oriented pillar-shaped transistor coupled to the second vertically-oriented pillar-shaped transistor;
a fifth vertically-oriented pillar-shaped transistor disposed above the third vertically-oriented pillar-shaped transistor and the fourth vertically-oriented pillar-shaped transistor, the fifth vertically-oriented pillar-shaped transistor coupled to the third vertically-oriented pillar-shaped transistor and the fourth vertically-oriented pillar-shaped transistor; and
a first reversible resistance-switching memory element coupled to the first and third vertically-oriented pillar-shaped transistors, and a second reversible resistance-switching memory element coupled to the second and fourth vertically-oriented pillar-shaped transistors.
2. The content addressable memory cell of claim 1 , wherein each of the vertically-oriented pillar-shaped transistors comprises a field-effect transistor or a bipolar transistor.
3. The content addressable memory cell of claim 1 , wherein each of the reversible resistance-switching memory elements comprises one or more of a metal oxide, a solid electrolyte, a phase-change material, a magnetic material, and a carbon material.
4. The content addressable memory cell of claim 1 , wherein each of the reversible resistance-switching memory elements comprises one or more of NiO, Nb 2 O 5 , TiO 2 , HfO 2 , Al 2 O 3 , MgO x , CrO 2 , VO, BN, TaO 2 , Ta 2 O 3 , and AlN.
5. A content addressable memory array comprising a plurality of content addressable memory cells of claim 1 .
6. A content addressable memory cell for use with a bit line, a complementary bit line, a word select line, a read/write line, a search line, a complementary search line, and a match line, the content addressable memory cell comprising:
a first transistor comprising a first terminal coupled to the bit line, a second terminal coupled to the word select line, and a third terminal;
a first reversible resistance-switching element comprising a first terminal coupled to the third terminal of the first transistor, and a second terminal coupled to the read/write line;
a second transistor comprising a first terminal coupled to the complementary bit line, a second terminal coupled to the word select line, and a third terminal;
a second reversible resistance-switching element comprising a first terminal coupled to the third terminal of the second transistor, and a second terminal coupled to the read/write line;
a third transistor comprising a first terminal coupled to the search line, a second terminal coupled to the first terminal of the first reversible resistance-switching element and the third terminal of the first transistor, and a third terminal;
a fourth transistor comprising a first terminal coupled to the complementary search line, a second terminal coupled to the first terminal of the second reversible resistance-switching element and the third terminal of the second transistor, and a third terminal; and
a fifth transistor comprising a first terminal coupled to the match line, a second terminal coupled to the third terminal of the third transistor and the third terminal of the fourth transistor, and a third terminal coupled to GROUND.
7. The content addressable memory cell of claim 6 , wherein each of the first, second, third, fourth and fifth transistors comprises a vertically-oriented pillar-shaped transistor.
8. The content addressable memory cell of claim 6 , wherein each of the first, second, third, fourth and fifth transistors comprises a field-effect transistor or a bipolar transistor.
9. The content addressable memory cell of claim 6 , wherein the first and second reversible resistance-switching elements each comprise one or more of a metal oxide, a solid electrolyte, a phase-change material, a magnetic material, and a carbon material.
10. The content addressable memory cell of claim 6 , wherein the first and second reversible resistance-switching elements each comprise one or more of NiO, Nb 2 O 5 , TiO 2 , HfO 2 , Al 2 O 3 , MgO x , CrO 2 , VO, BN, TaO 2 , Ta 2 O 3 , and AlN.
11. A content addressable memory array comprising a plurality of content addressable memory cells of claim 6 .