Forming ferroelectric polymer memories
View Patent ↗In accordance with some embodiments, a ferroelectric polymer memory may be formed of a plurality of stacked layers. Each layer may be separated from the ensuing layer by a polyimide layer. The polyimide layer may provide reduced layer-to-layer coupling, and may improve planarization after the lower layer fabrication.
1. A method comprising:
coating a first metal layer with hexamethyldisilazane;
forming a copolymer layer including vinyledene fluoride and trifluoroethylene over said coating; and
after forming said copolymer layer, annealing to form a piezoelectric film.
2. The method of claim 1 including forming said coating in a vapor prime oven.
3. The method of claim 2 including forming said layers on a wafer and rotating said wafer.
4. The method of claim 1 including spin coating the copolymer.
5. The method of claim 4 including spin coating the copolymer in an organic solvent solution.
6. The method of claim 5 including heating the wafer to evaporate the organic solvent.
7. The method of claim 1 including before forming said copolymer layer, cooling said first metal layer.
8. The method of claim 1 including forming a second metal layer over said copolymer to form a first layer of ferroelectric polymer memory.
9. The method of claim 8 including plasma etching said second metal layer using a gas mixture including helium.
10. The method of claim 8 including forming a polyimide layer over said second metal layer.
11. The method of claim 10 including forming a second layer of a ferroelectric polymer memory over said polyimide layer.
12. The method of claim 11 including forming another polyimide layer over said second layer of ferroelectric polymer memory.
13. A method comprising:
coating a first metal layer with hexamethyldisilazane;
forming a layer of polymer over said coating, said polymer to act as a ferroelectric polymer in a ferroelectric polymer memory; and
plasma etching a second metal layer formed over said polymer at a radio frequency bias of less than 50 Watts and using a gas mixture including helium, said metal layers and polymer layer to form a first layer of ferroelectric polymer memory.
14. The method of claim 13 including forming a polyimide layer over said first layer of ferroelectric polymer memory.
15. The method of claim 14 including forming a second layer of a ferroelectric polymer memory and forming another polyimide layer over said second memory layer.
16. The method of claim 13 wherein forming a layer of polymer over said coating includes forming a copolymer layer including vinyledene fluoride and trifloroethylene over said coating.
17. The method of claim 16 including spin coating the copolymer in an organic solvent.
18. The method of claim 17 including evaporating the organic solvent using heat.
19. The method of claim 18 wherein plasma etching a second metal layer includes etching said metal layer with a selectivity greater then 1.25.
20. The method of claim 18 wherein plasma etching a second metal layer includes etching said metal layer with a selectivity greater than 2.
21. The method of claim 18 wherein plasma etching a second metal layer includes using a radio frequency bias from about 20 to about 30 Watts.
22. The method of claim 18 wherein plasma etching a second metal layer includes using a gas mixture including Cl 2 and BCL 3 .