Self aligned memory element and wordline
An organic polymer memory cell is provided having an organic polymer layer and an electrode layer formed over a first conductive (e.g., copper) layer (e.g., bitline). The memory cells are connected to a second conductive layer (e.g., forming a wordline), and more particularly the top of the electrode layer of the memory cells to the second conductive layer. Optionally, a conductivity facilitating layer is formed over the conductive layer. Dielectric material separates the memory cells. The memory cells are self-aligned with the bitlines formed in the first conductive layer and the wordlines formed in the second conductive layer.
1. A method for forming a memory cell comprising;
applying an organic polymer layer over a first conductive layer, the first conductive layer serving as a bitline;
applying an electrode layer over the organic polymer layer;
applying a second conductive layer over the electrode layer wherein the second conductive layer is in direct contact with the electrode layer;
etching the second conductive layer to form a wordline in the second conductive layer and isolate at least a portion of the organic polymer layer and the electrode layer; and,
applying a dielectric material to facilitate isolation of the organic polymer and the electrode layer.
2. The method of claim 1 further comprising:
forming a conductivity facilitating layer over the first conductive layer.
3. The method of claim 2 , the conductivity facilitating layer has two relatively stable oxidation reduction states that permit donation and acceptance of electrons or holes with the organic polymer layer.
4. The method of claim 2 , the conductivity facilitating layer is operative to facilitate charge transport between the electrode layer, first conductive layer, and the second conductive layer.
5. The method of claim 2 , the conductivity facilitating layer effectuates charge carrier injection into the organic polymer layer so as to increase a concentration of charge carriers and to modify conductivity of the organic polymer layer.
6. The method of claim 2 , comprising forming a backbone of a conjugated organic molecule adjacent the conductivity facilitating layer, that grows or assembles away and substantially perpendicular to the conductivity facilitating layer surface, so as to align the conjugated organic molecule in a direction substantially perpendicular to a memory cell stack.
7. The method of claim 1 , the organic polymer layer being selected from the group comprising: polyacetylene, polyphenylacetylene, polydiphenylacetylene, polyaniline, poly(p-phenylene vinylene), polythiophene, polyporphyrins, porphyrinic macrocycles, thiol derivatized polyporphyrins, polymetallocenes, polyferrocenes, polyphthalocyanines, polyvinylenes, polypyrroles, polydiphenylacetylene and polystiroles.
8. The method of claim 1 wherein the electrode layer comprises at least one of amorphous carbon, tantalum, tantalum nitride (TaN), titanium and titanium nitride (TiN).
9. The method of claim 1 wherein the organic polymer layer has a thickness of about 0.001 μm or more and about 5 μm or less.
10. The method of claim 1 , wherein the organic layer is formed via a chemical vapor deposition process.
11. The method of claim 1 , wherein the organic layer is formed via a gas phase reaction process.
12. The method of claim 1 , wherein the organic layer is formed via a spin coating process.
13. The method of claim 1 , wherein the electrode layer has a thickness within a range between about 100 Å to 1500 Å.
14. The method of claim 1 , wherein a thickness of the organic polymer layer is greater than the thickness of the electrode layer within the range of about 10 to about 500 times.
15. The method of claim 1 wherein the first conductive layer comprises at least one of copper, aluminum, chromium, germanium, gold, magnesium, manganese, indium, iron, nickel, palladium, platinum, silver, titanium, zinc, alloys thereof, indium-tin oxide, polysilicon, doped amorphous silicon, metal silicides, Hastelloy®, Kovar®, Invar, Monel®, Inconel®, brass, stainless steel and magnesium-silver alloy.
16. The method of claim 1 wherein the dielectric material comprises at least one of silicon oxide (SiO), silicon dioxide (SiO 2 ), silicon nitride (Si 3N 4 ), (SiN), silicon oxynitride (SiO x N y ), fluorinated silicon oxide (SiO x F y ), polysilicon, amorphous silicon, tetraethyorthosilicate (TEOS), phosphosilicate glass (PSG) and borophosphosilicate glass (BPSG).
17. The method of claim 1 , comprising forming a photoresist layer over the electrode layer to facilitate etching etching portions of the electrode layer, the organic polymer layer, or the first conductive layer, or suitable combinations thereof, the photoresist layer having a thickness suitable for functioning as a mask for etching underlying layers.
18. The method of claim 1 , wherein the second conductive layer includes deposited aluminum.
19. The method of claim 1 , wherein etching the second conductive layer further includes etching portions of the electrode layer, the organic polymer layer, or the first conductive layer, or suitable combinations thereof, to facilitate isolation of organic polymer layer and the electrode layer.
20. The method of claim 1 , the organic polymer layer is comprised of a conjugated organic material having two relatively stable oxidation-reduction states.