Nonvolatile resistive memory element with a metal nitride containing switching layer
View Patent ↗A nonvolatile resistive memory element has a novel variable resistance layer that includes a metal nitride, a metal oxide-nitride, a two-metal oxide-nitride, or a multilayer stack thereof. One method of forming the novel variable resistance layer comprises an interlayer deposition procedure, in which metal oxide layers are interspersed with metal nitride layers and then converted into a substantially homogeneous layer by an anneal process. Another method of forming the novel variable resistance layer comprises an intralayer deposition procedure, in which various ALD processes are sequentially interleaved to form a metal oxide-nitride layer. Alternatively, a metal oxide is deposited, nitridized, and annealed to form the variable resistance layer or a metal nitride is deposited, oxidized, and annealed to form the variable resistance layer.
1. A method of forming a nonvolatile memory element, the method comprising:
forming a first layer, wherein the first layer is operable as an electrode;
depositing a second layer comprising a first metal layer above the first layer using an atomic layer deposition (ALD) process;
oxidizing the first metal layer by heating the first metal layer while exposing the first metal layer to an oxygen-containing gas;
depositing a third layer comprising a second metal layer above the oxidized first metal layer using an ALD process;
diffusing nitrogen into the second metal layer by exposing the second metal layer to a nitrogen-containing gas; and
forming a fourth layer operable as an electrode, so that the second layer and the third layer are disposed between the first layer and the fourth layer;
wherein the diffusing of nitrogen into the second metal layer comprises fully nitridizing the second metal layer.
2. The method of claim 1 , wherein the oxidizing of the first metal layer comprises fully oxidizing the first metal layer.
3. The method of claim 1 , further comprising performing a thermal anneal process to form a substantially homogeneous material from the oxidized first metal layer and the nitridized second metal layer.
4. The method of claim 1 , wherein the first metal layer and the second metal layer comprise different metallic chemical elements.
5. The method of claim 4 , wherein one of the second layer and the third layer comprises silicon.
6. The method of claim 4 , wherein the second layer and the third layer each comprise at least one of the chemical elements selected from the group of elements consisting of hafnium (Hf), zirconium (Zr), aluminum (Al), tantalum (Ta) titanium (Ti), vanadium (V), niobium (Nb), and tungsten (W).