Memory cells and methods of forming memory cells
Some embodiments include a method of forming a memory cell. A first portion of a switching region is formed over a first electrode. A second portion of the switching region is formed over the first portion using atomic layer deposition. The second portion is a different composition than the first portion. An ion source region is formed over the switching region. A second electrode is formed over the ion source region. Some embodiments include a memory cell having a switching region between a pair of electrodes. The switching region is configured to be reversibly transitioned between a low resistive state and a high resistive state. The switching region includes two or more discrete portions, with one of the portions not having a non-oxygen component in common with any composition directly against it in the high resistive state.
1. A method of forming a memory cell, comprising:
depositing multiple layers of different composition relative to one another over a first electrode, a first layer of the multiple layers comprising a composition containing one or more members of the group consisting of Al, Si and Mg, and a second layer of the multiple layers comprising one or more members of the group consisting of Zr, Ti and Hf;
merging the layers to form a switching region having a combined composition from the layers; and
forming a second electrode over the switching region.
2. The method of claim 1 wherein the layers are formed utilizing one or more of ALD, CVD and PVD.
3. The method of claim 1 wherein the layers are formed to thicknesses within a range of from greater than 0 angstroms to less than or equal to about 20 angstroms utilizing ALD.
4. The method of claim 1 wherein the second layer comprises hafnium oxide and the first layer comprises silicon oxide.
5. The method of claim 1 wherein the second layer comprises hafnium oxide and the first layer comprises aluminum oxide.
6. The method of claim 1 wherein the layers comprise aluminum oxide and silicon oxide.
7. A method of forming a memory cell, comprising:
forming a first portion of a switching region over a first electrode;
forming a second portion of the switching region in contact with the first portion, the first and second portions being discreet portions, each of the first and second portions comprising one or more non-oxygen component, each non-oxygen component in each of the first and second portions differing from all non-oxygen components present in any material in direct physical contact with the respective portion, one of the first and second portion comprising one or more members of the group consisting of Ti, Zr and Hf, and the other of the first and second portion comprising one or more members of the group consisting of Mg, Al and Si;
forming an ion source region over the switching region, the ion source region being configured to contribute one or both of silver cations and aluminum cations; and
forming a second electrode over the ion source region.
8. The method of claim 7 wherein the ion source region comprises one or more of aluminum, copper, silver and tellurium.
9. The method of claim 7 wherein the forming the ion source region comprises:
forming a first material comprising AlTeN over the switching region, where the listed composition is described in terms of elemental constituents rather than in terms of a specific stoichiometry; and
forming a second material over the first material; the second material comprising CuZrAlTeO, where the listed composition is described in terms of elemental constituents rather than in terms of a specific stoichiometry.
10. The method of claim 7 wherein the forming the first portion comprises depositing one or more transition metals.