SEMICONDUCTOR STORAGE DEVICE AND MANUFACTURING METHOD THEREOF
Since a chalcogenide material has low adhesion to a silicon oxide film, there is a problem in that it tends to separate from the film during the manufacturing step of a phase change memory. In addition, since the chalcogenide material has to be heated to its melting point or higher during resetting (amorphization) of the phase change memory, there is a problem of requiring extremely large rewriting current. An interfacial layer includes an extremely thin insulator or semiconductor having the function as both an adhesive layer and a high resistance layer (thermal resistance layer) is inserted between chalcogenide material layer/interlayer insulative film and between chalcogenide material layer/plug.
1 . A semiconductor storage device including;
a semiconductor substrate;
a selection transistor formed on a main surface of the semiconductor substrate;
an inter-layer insulative film disposed over the selection transistor;
a plug selectively disposed to pass through the inter-layer insulative film and connected electrically with the selection transistor;
a chalcogenide material layer connected to one end of the plug and disposed so as to extend over the inter-layer insulative film;
an upper electrode disposed over the chalcogenide material layer; and
an interfacial layer formed between the chalcogenide material layer and the inter-layer insulative film so as to cover at least one end of the plug and comprising a continuous semiconductor not having a region where the chalcogenide material layer and the inter-layer insulative film are not in direct contact with each other.
2 . A semiconductor storage device according to claim 1 , wherein the interfacial layer comprises a material having higher adhesiveness than the inter-layer insulative film relative to the chalcogenide material layer.
3 . A semiconductor storage device according to claim 1 , wherein the interfacial layer comprises a material of lower heat conductivity than that of the plug.
4 . A semiconductor storage device according to claim 1 , wherein the interfacial layer comprises a material of higher resistivity than that of the plug.
5 . A semiconductor storage device according to claim 1 , wherein the interfacial layer has a film thickness of 0.5 nm or more and 5 nm or less and is formed in contact with the lower surface of the chalcogenide material layer.
6 . A semiconductor storage device according to claim 1 , wherein the interfacial layer comprising a material containing Si.
7 . A semiconductor storage device comprising;
a semiconductor substrate;
a selection transistor formed on a main surface of the semiconductor substrate;
an inter-layer insulative film disposed over the selection transistor;
a plug selectively disposed to pass through the inter-layer insulative film and connected electrically with the selection transistor;
a chalcogenide material layer connected to one end of the plug and disposed so as to extend over the inter-layer insulative film;
an upper electrode disposed over the chalcogenide material layer;
an adhesion layer comprising a semiconductor formed between the chalcogenide material layer and the inter-layer insulative film; and
an interfacial layer formed between the chalcogenide material layer and the plug and comprising an alloy of a material of the adhesion layer and a material of the plug.
8 . A semiconductor storage device according to claim 7 , wherein the adhesion layer and the interfacial layer comprise a material having higher adhesiveness than the inter-layer insulative film relative to the chalcogenide material layer.
9 . A semiconductor storage device according to claim 7 , wherein the adhesion layer and the interfacial layer comprise a material of lower heat conductivity than the plug.
10 . A semiconductor storage device according to claim 7 , wherein the adhesion layer and the interfacial layer comprise a material of higher resistivity than the plug.
11 . A semiconductor storage device according to claim 7 , wherein the adhesion layer and the interfacial layer have a film thickness of 0.5 nm or more and 5 nm or less and are formed in contact with the lower surface of the chalcogenide material layer.
12 . A semiconductor storage device according to claim 7 , wherein the interfacial layer comprises a material containing Si.
13 . A semiconductor storage device including:
a plug;
a phase change material layer formed on the plug; and
an electrode formed on the phase change material layer, wherein the semiconductor storage device stores data according to a phase state of a region of the phase change material layer that is continuous between the plug and the electrode, and
further includes a boundary layer formed between the plug and the phase change material layer and comprised of a semiconductor film having such a thickness that a tunnel current flows.
14 . A semiconductor storage device according to claim 13 , wherein the phase change material layer contains a chalcogenide material.
15 . A semiconductor storage device according to claim 13 , wherein the boundary layer has a film thickness of 0.5 nm or more.
16 . A semiconductor storage device according to claim 13 , wherein the boundary layer has a film thickness of 5 nm or less.
17 . A semiconductor storage device according to claim 13 , wherein the boundary layer comprises a material containing Si.
18 . A semiconductor storage device including:
a plug;
a phase change material layer formed on the plug; and
an electrode formed on the phase change material layer,
wherein the semiconductor storage device stores data according to a phase state of a region of the phase change material layer that is continuous between the plug and the electrode, and
further includes a boundary layer formed between the plug and the phase change material layer and comprised of an alloy of a semiconductor material and a material applying to the plug.
19 . A semiconductor storage device according to claim 18 , wherein the phase change material layer contains a chalcogenide material.
20 . A semiconductor storage device according to claim 18 , wherein the boundary layer comprises a material containing Si.