Memory device with a plurality of metal chalcogenide layers

A memory device comprising:

• a first conductive layer;
• a second conductive layer;
• a resistance change region provided between the first conductive layer and the second conductive layer;
• a first region provided between the resistance change region and the first conductive layer, the first region including a first substance selected from the group consisting of carbon, niobium sulfide, tantalum sulfide, titanium sulfide, niobium selenide, tantalum selenide, tantalum telluride, bismuth selenide, indium selenide, and gallium telluride;
• a second region provided between the first region and the resistance change region, the second region including a second substance selected from the group consisting of molybdenum sulfide, tungsten sulfide, molybdenum selenide, tungsten selenide, molybdenum telluride, tungsten telluride, zirconium sulfide, zirconium selenide, hafnium sulfide, and hafnium selenide;
• and
• a third region provided between the second region and the resistance change region, the third region including the first substance.

A memory device comprising:

• a plurality of first wires;
• a plurality of second wires intersecting with the first wires;
• and
• a memory cell disposed in at least one of regions where the first wires intersect with the second wires, wherein
• the memory cell includes:
• a resistance change region provided between the first wire and the second wire;
• a first region provided between the resistance change region and the first wire, the first region including a first element selected from the group consisting of niobium (Nb), vanadium (V), tantalum (Ta), and titanium (Ti), and a second element selected from the group consisting of oxygen (O), sulfur (S), selenium (Se), and tellurium (Te), the first region having a first atomic ratio of the first element to the second element;
• and
• a second region provided between the first region and the resistance change region, the second region including the first element and the second element, the second region having a second atomic ratio of the first element to the second element, the second atomic ratio being smaller than the first atomic ratio.

A memory device comprising:

• a first conductive layer;
• a second conductive layer;
• a resistance change region provided between the first conductive layer and the second conductive layer;
• a first region provided between the resistance change region and the first conductive layer, the first region including a first substance selected from the group consisting of carbon, niobium sulfide, tantalum sulfide, titanium sulfide, niobium selenide, tantalum selenide, tantalum telluride, bismuth selenide, indium selenide, and gallium telluride;
• a second region provided between the first region and the resistance change region, the second region including a second substance selected from the group consisting of molybdenum sulfide, tungsten sulfide, molybdenum selenide, tungsten selenide, molybdenum telluride, tungsten telluride, zirconium sulfide, zirconium selenide, hafnium sulfide, and hafnium selenide;
• and
• a third conductive layer provided between the second region and the resistance change region,
• wherein
• the first region has a thickness equal to or less than 1 nm in a direction from the first conductive layer to the second conductive layer, and
• the second region has a thickness equal to or less than 1 nm in the direction.