MAGNETIC RANDOM ACCESS MEMORY (MRAM) BIT CELLS EMPLOYING SOURCE LINES (SLs) AND/OR BIT LINES (BLs) DISPOSED IN MULTIPLE, STACKED METAL LAYERS TO REDUCE MRAM BIT CELL RESISTANCE
First Claim
1. An integrated circuit (IC) comprising at least one magnetic random access memory (MRAM) bit cell, the at least one MRAM bit cell, comprising:
- an access transistor disposed in a semiconductor layer of the IC, the access transistor comprising a gate, a source, and a drain;
a magnetic tunnel junction (MTJ) disposed in a metal layer in the IC disposed above the semiconductor layer, the MTJ comprising a first end electrode and a second end electrode;
a drain-side connection column disposed in at least one metal layer in the IC above the semiconductor layer coupling the drain of the access transistor to the first end electrode of the MTJ;
a bit line disposed in at least one metal layer in the IC above the semiconductor layer coupled to the second end electrode of the MTJ; and
a source line disposed in a plurality of stacked metal layers in the IC above the semiconductor layer and coupled to the source of the access transistor.
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Accused Products
Abstract
Magnetic random access memory (MRAM) bit cells employing source lines and/or bit lines disposed in multiple, stacked metal layers to reduce MRAM bit cell resistance are disclosed. Related methods and systems are also disclosed. In aspects disclosed herein, MRAM bit cells are provided in a memory array. The MRAM bit cells are fabricated in an integrated circuit (IC) with source lines and/or bit lines formed by multiple, stacked metal layers disposed above a semiconductor layer to reduce the resistance of the source lines. In this manner, if node size in the IC is scaled down, the resistance of the source lines and/or the bit lines can be maintained or reduced to avoid an increase in drive voltage that generates a write current for write operations for the MRAM bit cells.
13 Citations
49 Claims
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1. An integrated circuit (IC) comprising at least one magnetic random access memory (MRAM) bit cell, the at least one MRAM bit cell, comprising:
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an access transistor disposed in a semiconductor layer of the IC, the access transistor comprising a gate, a source, and a drain; a magnetic tunnel junction (MTJ) disposed in a metal layer in the IC disposed above the semiconductor layer, the MTJ comprising a first end electrode and a second end electrode; a drain-side connection column disposed in at least one metal layer in the IC above the semiconductor layer coupling the drain of the access transistor to the first end electrode of the MTJ; a bit line disposed in at least one metal layer in the IC above the semiconductor layer coupled to the second end electrode of the MTJ; and a source line disposed in a plurality of stacked metal layers in the IC above the semiconductor layer and coupled to the source of the access transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of fabricating a magnetic random access memory (MRAM) bit cell in an integrated circuit (IC), comprising:
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forming an access transistor in a semiconductor layer, the access transistor comprising a gate, a source, and a drain; forming a magnetic tunnel junction (MTJ) in a metal layer disposed above the semiconductor layer, the MTJ comprising a first end electrode and a second end electrode; forming a drain-side connection column in at least one metal layer in the IC above the semiconductor layer coupling the drain of the access transistor to the first end electrode of the MTJ; forming a bit line in at least one metal layer above the semiconductor layer coupled to the second end electrode of the MTJ; and forming a source line in a plurality of stacked metal layers in the IC above the semiconductor layer coupled to the source of the access transistor. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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29. An integrated circuit (IC) comprising at least one magnetic random access memory (MRAM) bit cell, the at least one MRAM bit cell, comprising:
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an access transistor disposed in a semiconductor layer of the IC, the access transistor comprising a gate, a source, and a drain; a magnetic tunnel junction (MTJ) disposed in a metal layer in the IC disposed above the semiconductor layer, the MTJ comprising a first end electrode and a second end electrode; a drain-side connection column disposed in at least one metal layer in the IC above the semiconductor layer coupling the drain of the access transistor to the first end electrode of the MTJ; a source line disposed in at least one metal layers in the IC above the semiconductor layer and coupled to the source of the access transistor; and a bit line disposed in a plurality of stacked metal layers in the IC above the semiconductor layer coupled to the second end electrode of the MTJ. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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46. A method of fabricating a magnetic random access memory (MRAM) bit cell in an integrated circuit (IC), comprising:
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forming an access transistor in a semiconductor layer, the access transistor comprising a gate, a source, and a drain; forming a magnetic tunnel junction (MTJ) in a metal layer disposed above the semiconductor layer, the MTJ comprising a first end electrode and a second end electrode; forming a drain-side connection column in at least one metal layer in the IC above the semiconductor layer coupling the drain of the access transistor to the first end electrode of the MTJ; forming a source line in at least one metal layer above the semiconductor layer coupled to the source of the access transistor; and forming a bit line in a plurality of stacked metal layers in the IC above the semiconductor layer coupled to the second end electrode of the MTJ. - View Dependent Claims (47, 48, 49)
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Specification