METHOD FOR FABRICATION OF A CEM DEVICE
Disclosed is a method for the fabrication of a correlated electron material (CEM) device to an comprising: forming a layer of a conductive substrate on a substrate; forming a layer of a correlated electron material on the layer of conductive substrate; forming a layer of a conductive overlay on the layer of correlated electron material; patterning these layers to form a stack comprising a conductive substrate, a CEM layer and a conductive overlay on the substrate; forming a cover layer of an insulating material over the stack; and patterning the cover layer wherein: the patterning of the cover layer comprises etching a via in the cover layer whereby to expose a part of the upper surface of the conductive overlay and etching a trench in the cover layer such that the trench surrounds the via.
1 . A method for the fabrication of a correlated electron material (CEM) device comprising:
forming a layer of a conductive substrate over a substrate;
forming a layer of a CEM over the layer of conductive substrate, the layer of the CEM providing a bulk switch such that a majority volume of the CEM in the layer of the CEM is switchable between impedance states through a reversible electron back-donation;
forming a layer of a conductive overlay over the layer of the CEM;
patterning the layer of the conductive substrate, the layer of the CEM and the layer of the conductive overlay to form a stack comprising a conductive substrate, a CEM layer and a conductive overlay on the substrate;
forming a cover layer of an insulating material over the stack; and
patterning the cover layer wherein:
the patterning of the cover layer comprises etching a first via aperture in the cover layer to expose a part of an upper surface of the conductive overlay and etching a trench aperture in the cover layer such that the trench aperture surrounds the first via aperture.
2 . The method according to claim 1 , comprising etching the first via aperture prior to etching the trench aperture.
3 . The method according to claim 1 , comprising etching a second via aperture in the cover layer.
4 . The method according to claim 3 , comprising etching the second via aperture concurrently with etching the first via aperture.
5 . The method according to claim 3 , comprising etching the second via aperture after completion of etching the first via aperture and prior to commencement of etching the trench aperture.
6 . The method according to claim 3 , comprising etching the trench aperture in the cover layer to surround the first via aperture and the second via aperture, or etching a first trench aperture in the cover layer to surround the first via aperture and a second trench aperture in the cover layer to surround the second via aperture.
7 . The method according to claim 3 , wherein the first via aperture and the second via aperture have different depths in the cover layer.
8 . The method according to claim 1 , wherein the first via aperture and the trench aperture provide for full contact of an upper metal interconnect over a surface of the conductive overlay.
9 . The method according to claim 6 , wherein the second via aperture and the second trench aperture provide for full contact of the upper metal interconnect over a surface of a lower metal interconnect within the substrate.
10 . The method according to claim 1 , further comprising depositing a moisture barrier layer over the stack prior to forming the cover layer.
11 . The method according to claim 1 , further comprising depositing a metal barrier layer over the conductive overlay and at least the interior walls of the first via aperture and the trench aperture.
12 . The method according to claim 11 , further comprising depositing a metal interconnect over the conductive overlay and the metal barrier layer in the first via aperture and the trench aperture.
13 . An integrated circuit having a correlated electron material (CEM) device comprising a conductive substrate, a CEM layer and a conductive overlay wherein the device is arranged between an upper metal interconnect provided in a cover layer and a lower metal interconnect provided in a substrate, the lower metal interconnect having a via contact with the conductive substrate, and wherein the upper metal interconnect has a via contact with the conductive overlay.
14 . An integrated circuit according to claim 13 , wherein the upper metal interconnect fully contacts an upper surface of the conductive overlay.
15 . An integrated circuit according to claim 13 , wherein a second lower metal interconnect is provided in the substrate and the upper metal interconnect has a second via contact with the second lower metal interconnect.
16 . An integrated circuit according to claim 13 , wherein a moisture barrier layer is present on substantially the whole of the sidewalls of the conductive overlay, the CEM layer and the conductive substrate.
17 . An electronic device comprising an integrated circuit having a CEM device comprising a conductive substrate, a CEM layer and a conductive overlay wherein the device is provided between an upper metal interconnect and a lower metal interconnect, the lower metal interconnect having a via contact with the conductive substrate, and wherein the upper metal interconnect has a via contact with the conductive overlay.
18 . An electronic device according to claim 17 , wherein the upper metal interconnect fully contacts an upper surface of the conductive overlay.
19 . An electronic device according to claim 17 , wherein a second lower metal interconnect is provided in the substrate and the upper metal interconnect has a second via contact with the second lower metal interconnect.
20 . An electronic device according to claim 17 , wherein a moisture barrier layer is present on substantially the whole of the sidewalls of the conductive overlay, the CEM layer and the conductive substrate.