Disclosed are methods of making memory cells and semiconductor devices containing the memory cells. The methods involve oxidizing a portion of a copper containing electrode to form a copper oxide layer; contacting the copper oxide layer with at least one of a sulfur containing gas or plasma to form a CuS layer; forming an organic semiconductor over the CuS layer; and forming an electrode over the organic semiconductor. Such devices containing the memory cells are characterized by light weight and robust reliability.
1. A method of making a memory cell, comprising:
providing a first electrode comprising at least copper;
oxidizing a portion of the first electrode to form a copper oxide layer on the first electrode;
contacting the copper oxide layer with at least one of a sulfur containing gas and a sulfur containing plasma to convert at least a substantial portion of the copper oxide layer to a CuS layer;
forming an organic semiconductor over the CuS layer; and
forming a second electrode over the organic semiconductor.
2. The method of claim 1 , wherein the first electrode is oxidized with a liquid comprising at least one selected from the group consisting of hydrogen peroxide, water, and oxygenated water.
3. The method of claim 1 , wherein the first electrode is oxidized with a gas or plasma comprising at least one selected from the group consisting of steam, oxygen, ozone, and N 2 O.
4. The method of claim 1 , wherein the sulfur containing gas comprises at least one selected from the group consisting of SO 2 and SO 3 .
5. The method of claim 1 , wherein the sulfur containing plasma comprises at least one selected from the group consisting of SO 2 and SO 3 .
6. The method of claim 1 , wherein the copper oxide layer is contacted with at least one of a sulfur containing gas and a sulfur containing plasma at a temperature from about 10° C. to about 500° C. for a time from about 5 seconds to about 10 minutes.
7. The method of claim 1 , wherein the CuS layer comprises at least one compound represented by the formula Cu x S y , where x and y are independently from about 0.5 to about 4.
8. The method of claim 1 , wherein the CuS layer is treated with a plasma before forming the organic semiconductor over the CuS layer.
9. The method of claim 1 , wherein the organic semiconductor comprises at least one selected from the group consisting of polyacetylene; polydiphenylacetylene; poly(t-butyl)diphenylacetylene; poly(trifluoromethyl)diphenylacetylene; polybis(trifluoromethyl)acetylene; polybis(t-butyldiphenyl)acetylene; poly(trimethylsilyl)diphenylacetylene; poly(carbazole)diphenylacetylene; polydiacetylene; polyphenylacetylene; polypyridineacetylene; polymethoxyphenylacetylene; polymethylphenylacetylene; poly(t-butyl)phenylacetylene; polynitro-phenylacetylene; poly(trifluoromethyl)phenylacetylene; poly(trimethylsilyl)pheylacetylene; polydipyrrylmethane; polyindoqiunone; polydihydroxyindole; polytrihydroxyindole; furane-polydihydroxyindole; polyindoqiunone-2-carboxyl; polyindoqiunone; polybenzobisthiazole; poly(p-phenylene sulfide); polyaniline; polythiophene; polypyrrole; polysilane; polystyrene; polyfuran; polyindole; polyazulene; polyphenylene; polypyridine; polybipyridine; polyphthalocyanine; polysexithiofene; poly(siliconoxohemiporphyrazine); poly(germaniumoxohemiporphyrazine); poly(ethylenedioxythiophene); polymetallocene complexes; and polypyridine metal complexes.
10. A method of making a memory cell, comprising:
providing a first electrode comprising at least 50% by weight copper;
contacting the first electrode with an oxidizing compound to form a copper oxide layer on the first electrode;
contacting the copper oxide layer with at least one of a sulfur containing gas and a sulfur containing plasma to convert at least a substantial portion of the copper oxide layer to a CuS layer;
forming an organic semiconductor over the CuS layer; and
forming a second electrode over the organic semiconductor.
11. The method of claim 10 , wherein the oxidizing compound is selected from the group consisting of hydrogen peroxide, water, oxygenated water, steam, oxygen, ozone, and N 2 O.
12. The method of claim 10 , wherein the copper oxide layer has a thickness of about 10 Å or more and about 0.01 μm or less.
13. The method of claim 10 , wherein the sulfur containing plasma contains from about 10 sccm to about 10 slm of sulfur dioxide and from about 0 sccm to about 10 slm of at least one inert gas; the sulfur containing plasma contacting the copper oxide layer at a temperature from about 10° C. to about 500° C. for a time from about 1 second to about 1 hour.
14. The method of claim 10 , wherein the sulfur containing gas comprises from about 1% to about 100% by weight of sulfur dioxide and from about 0% to about 99% by weight of at least one inert gas; the sulfur containing gas contacting the copper oxide layer at a temperature from about 10° C. to about 500° C. for a time from about 1 second to about 1 hour.
15. The method of claim 10 , wherein the CuS layer has a thickness of about 10 Å or more and about 0.01 μm or less.
16. The method of claim 10 , wherein the organic semiconductor comprises at least one selected from the group consisting of polyacetylene; polydiphenylacetylene; poly(t-butyl)diphenylacetylene; poly(trifluoromethyl)diphenylacetylene; polybis(trifluoromethyl)acetylene; polybis(t-butyldiphenyl)acetylene; poly(trimethylsilyl)diphenylacetylene; poly(carbazole)diphenylacetylene; polydiacetylene; polyphenylacetylene; polypyridineacetylene; polymethoxyphenylacetylene; polymethylphenylacetylene; poly(t-butyl)phenylacetylene; polynitro-phenylacetylene; poly(trifluoromethyl)phenylacetylene; poly(trimethylsilyl)pheylacetylene; polydipyrrylmethane; polyindoqiunone; polydihydroxyindole; polytrihydroxyindole; furane-polydihydroxyindole; polyindoqiunone-2-carboxyl; polyindoqiunone; polybenzobisthiazole; poly(p-phenylene sulfide); polyaniline; polytbiophene; polypyrrole; polysilane; polystyrene; polyfuran; polyindole; polyazulene; polyphenylene; polypyridine; polybipyridine; polyphthalocyanine; polysexithiofene; poly(siliconoxohemiporphyrazine); poly(germaniumoxohemiporphyrazine); poly(ethylenedioxythiophene); polymetallocene complexes; and polypyridine metal complexes.
17. A method of making a memory cell, comprising:
providing a first electrode comprising at least copper;
oxidizing a portion of the first electrode to form a copper oxide layer on the first electrode;
contacting the copper oxide layer with at least one of a sulfur dioxide containing gas and a sulfur dioxide containing plasma to convert at least a substantial portion of the copper oxide layer to a CuS layer;
forming an organic semiconductor comprising a conjugated organic polymer over the CuS layer; and
forming a second electrode over the organic semiconductor.
18. The method of claim 17 , wherein the first electrode is oxidized with at least one of a liquid comprising at least one selected from the group consisting of hydrogen peroxide, water, and oxygenated water; a gas comprising at least one selected from the group consisting of steam, oxygen, ozone, and N 2 O; and a plasma comprising at least one selected from the group consisting of steam, oxygen, ozone, and N 2 O.
19. The method of claim 17 , wherein the copper oxide layer is contacted with a sulfur dioxide containing gas comprising from about 3% to about 95% by weight of sulfur dioxide and from about 5% to about 97% by weight of at least one inert gas.
20. The method of claim 17 , with the proviso that the copper oxide layer is not contacted with H 2 S.