Resistive random access memory cells having variable switching characteristics
First Claim
1. A method comprising:
- providing a first resistive random access memory (ReRAM) cell,the first ReRAM cell comprising a top electrode, a bottom electrode, and a resistive switching layer disposed between the top electrode and the bottom electrode,the top electrode having a different composition than the bottom electrode;
setting an initial conductive path through the resistive switching layer of the first ReRAM cell,wherein the forming the initial conductive path comprisespassing an electrical current in a direction from the top electrode to the bottom electrode of the first ReRAM cell,wherein a resistance of the resistive switching layer decreases while the electrical current is passed in the direction from the top electrode to the bottom electrode of the first ReRAM cell and the initial conductive path is set through the resistive switching layer;
breaking the initial conductive path within the resistive switching layer of the first ReRAM cell,wherein the breaking comprises passing an electrical current in a direction from the bottom electrode to the top electrode of the first ReRAM cell,wherein the resistance of the resistive switching layer increases while the electrical current is passed in the direction from the bottom electrode to the top electrode of the first ReRAM cell and the initial conductive path is broken within the resistive switching layer; and
setting a new conductive path through the resistive switching layer of the first ReRAM cell,wherein setting the new conductive path comprises passing an electrical current in a direction from the bottom electrode to the top electrode of the first ReRAM cell,wherein the resistance of the resistive switching layer decreases while the electrical current is passed in the direction from the bottom electrode to the top electrode of the first ReRAM cell and the new conductive path is set through the resistive switching layer.
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Abstract
Provided are resistive random access memory (ReRAM) cells forming arrays and methods of operating such cells and arrays. The ReRAM cells of the same array may have the same structure, such as have the same bottom electrodes, top electrodes, and resistive switching layers. Yet, these cells may be operated in a different manner. For example, some ReRAM cells may be restively switched using lower switching voltages than other cells. The cells may also have different data retention characteristics. These differences may be achieved by using different forming operations for different cells or, more specifically, flowing forming currents in different directions for different cells. The resulting conductive paths formed within the resistive switching layers are believed to switch at or near different electrode interfaces, i.e., within a so called switching zone. In some embodiments, a switching zone of a ReRAM cell may be changed even after the initial formation.
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Citations
14 Claims
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1. A method comprising:
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providing a first resistive random access memory (ReRAM) cell, the first ReRAM cell comprising a top electrode, a bottom electrode, and a resistive switching layer disposed between the top electrode and the bottom electrode, the top electrode having a different composition than the bottom electrode; setting an initial conductive path through the resistive switching layer of the first ReRAM cell, wherein the forming the initial conductive path comprises passing an electrical current in a direction from the top electrode to the bottom electrode of the first ReRAM cell, wherein a resistance of the resistive switching layer decreases while the electrical current is passed in the direction from the top electrode to the bottom electrode of the first ReRAM cell and the initial conductive path is set through the resistive switching layer; breaking the initial conductive path within the resistive switching layer of the first ReRAM cell, wherein the breaking comprises passing an electrical current in a direction from the bottom electrode to the top electrode of the first ReRAM cell, wherein the resistance of the resistive switching layer increases while the electrical current is passed in the direction from the bottom electrode to the top electrode of the first ReRAM cell and the initial conductive path is broken within the resistive switching layer; and setting a new conductive path through the resistive switching layer of the first ReRAM cell, wherein setting the new conductive path comprises passing an electrical current in a direction from the bottom electrode to the top electrode of the first ReRAM cell, wherein the resistance of the resistive switching layer decreases while the electrical current is passed in the direction from the bottom electrode to the top electrode of the first ReRAM cell and the new conductive path is set through the resistive switching layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification