Forming interconnects using locally deposited solvents
View Patent ↗A method for forming an electronic device, comprising: forming a first conductive or semiconductive layer; forming a sequence of at least on insulating layer and at least one semiconducting layer over the first conductive or semiconductive layer; locally depositing solvents at a localised region of the insulating layer so as to dissolve the sequence of insulating and semiconducting layers in the region to leave a void extending through the sequence of layer; and depositing conductive or semiconductive material in the void.
1. A method for forming an electronic device, comprising:
forming a first conductive or semiconductive layer;
forming a sequence of at least one insulating layer and at least one semiconducting layer over the first conductive or semiconductive layer;
locally depositing solvents at a localised region of the sequence so as to than a void in the sequence with material dissolved to form said void being redeposited at a side of the void; and
depositing conductive or semiconductive material in the void.
2. A method as claimed in claim 1 , wherein the solvents are deposited simultaneously.
3. A method as claimed in claim 1 , wherein the solvents arc deposited sequentially.
4. A method as claimed in claim 1 , wherein the first layer is substantially insoluble in the said solvent or solvents.
5. A method as claimed in claim 4 , wherein the first layer comprises a semiconductive conjugated polymer.
6. A method as claimed in claim 4 , wherein the first layer comprises F8T2 or TFB.
7. A method as claimed in claim 4 , wherein the first layer is an active layer of the electronic device.
8. A method as claimed in claim 4 , comprising the step of depositing a conductive layer under the first layer.
9. A method as claimed in claim 8 , wherein the conductive layer is an electrode of the electronic device.
10. A method as claimed in claim 4 , wherein the first layer comprises a conductive conjugated polymer.
11. A method as claimed in claim 4 , wherein the volume of the said solvent or solvents is greater than that required to dissolve the sequence of insulating and semiconducting layers in the region.
12. A method as claimed in claim 1 , comprising forming a further conductive or semiconductive layer over the sequence of insulating and semiconducting layers or the insulating layer and in contact with the material in the void.
13. A method as claimed in claim 12 , wherein the first conductive a semiconductive layer forms an electrode or an interconnect.
14. A method as claimed in claim 12 , wherein the further conductive or semiconductive layer forms an electrode or an interconnect.
15. A method as claimed in claim 1 , wherein the said solvent or solvents are deposited by ink jet printing.
16. A method as claimed in claim 15 , wherein the said solvent or solvents are deposited as a single droplet by ink-jet printing.
17. A method as claimed in claim 15 , wherein the said solvent or solvents are deposited as a plurality of droplets by ink-jet printing.
18. A method as claimed in claim 1 , wherein the boiling point of the said solvent or of the said solvents in combination is greater than 80° C.
19. A method as claimed in claim 1 , wherein the boiling point of the said solvent or of the said solvents in combination is greater than 100° C.
20. A method as claimed in claim 1 , wherein the hailing point of the said solvent or of the said solvents in combination is less than 100° C.
21. A method as claimed in claim 1 , wherein each of the insulating and semiconducting layers has a solubility greater than 1 weight percent per volume in one or more of the said solvents.
22. A method as claimed in claim 1 , wherein each of the insulating and semiconducting layers has a solubility greater than 2 weight percent per volume in one or more of the said solvents.
23. A method as claimed in claim 1 , in which the volume of deposited solvent is less than 50 pl.
24. A method as claimed in claim 1 , in which the volume of deposited solvent is less than 20 pl.
25. A method as claimed in claim 1 , in which the volume of deposited solvent is less than 5 pl.
26. A method as claimed in claim 1 , in which the contact angle of the deposited solvent on the layer or sequence of layers to be dissolved is larger than 50°, but less than 90°.
27. A method as claimed in claim 1 , in which the contact angle of the deposited solvent on the layer or sequence of layers to be dissolved is larger than 20°, bin less than 90°.
28. A method as claimed in claim 1 , in which the contact angle of the deposited solvent on the layer or sequence of layers to be dissolved is larger than 50°, but less than 90°.
29. A method as claimed in claim 1 , in which the surface of the layer or sequence of layers to be dissolved has been treated in order to provide a greater repellence for the deposited solvent droplets.
30. A method as claimed in claim 29 , in which the surface treatment is provided by deposition of a self-assembled monolayer.
31. A method as claimed in claim 1 , wherein the electronic device is a transistor and the material deposited in the void forms a via hole interconnect between electrodes and/or interconnect lines in different layers of the device.
32. A method as claimed in claim 1 , wherein the solvent or one of the solvents is an alcohol.
33. A method as claimed in claim 1 , wherein the solvent or one of the solvents is IPA or methanol.
34. A method as claimed in claim 1 , comprising the step of forming a confinement structure for confining the solvent or solvents to the localised region by means of its wetting properties.
35. A method as in claim 34 , wherein the confinement structure is provided by a self-assembled monolayer.
36. A method as claimed in any claim 1 wherein the insulating layer comprises PVP.
37. A method as claimed in claim 1 , wherein one of the insulating layer and a layer directly underlying it is soluble in a polar solvents and the other of the insulating layer and the layer directly underlying it is soluble in a non-polar solvent.
38. A method as claimed in claim 1 , wherein the local deposition is carried out using a printing technique.
39. A method as claimed in claim 1 , wherein the local deposition of the solvents is carried out by locally depositing the solvents as droplets by ink-jet printing.
40. A method for forming an electronic device, comprising:
forming a first conductive or semiconductive layer;
forming a soluble insulating layer over the first conductive or semiconductive layer;
locally depositing a solvent at a localised region of the insulating layer so as to form a void in the insulating layer with material dissolved to form said void redeposited at a side of the void; and
depositing conductive or semiconductive material in the void.
41. A method as claimed in claim 40 , wherein the insulating layer has a solubility greater than 1 weight percent per volume in the said solvent.
42. A method as claimed in claim 40 , wherein the insulating layer has a solubility greater than 2 weight percent per volume in the said solvent.
43. A method as claimed in claim 40 , wherein the local deposition is carried alit using a printing technique.
44. A method as claimed in claim 40 , wherein the local deposition of the solvent is carried out by local depositing the solvent as one or more droplets by ink-jet printing.