The present invention provides a chemical-mechanical polishing (CMP) composition suitable for polishing a substrate comprising a phase change alloy (PCA), such as a germanium-antimony-tellurium (GST) alloy. The composition comprises not more than about 6 percent by weight of a particulate abrasive material in combination with an optional oxidizing agent, at least one chelating agent, and an aqueous carrier therefor. The chelating agent comprises a compound or combination of compounds capable of chelating a phase change alloy or component thereof (e.g., germanium, indium, antimony and/or tellurium species) that is present in the substrate, or chelating a substance that is formed from the PCA during polishing of the substrate with the CMP composition. A CMP method for polishing a phase change alloy-containing substrate utilizing the composition is also disclosed.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a plot of GST removal rate versus polishing duration for a CMP composition of the invention compared to a conventional CMP composition.
Claims
1. A chemical-mechanical polishing (CMP) composition for polishing a phase change alloy-containing substrate, the composition comprising:
(a) a particulate abrasive material in an amount of not more than about 3 percent by weight;(b) at least one chelating agent capable of chelating the phase change alloy, a component thereof, or a substance formed from the PCA material during chemical-mechanical polishing; and(c) an aqueous carrier therefor.
2. The CMP composition of claim 1 wherein the particulate abrasive material is present in an amount of not more than about 1 percent by weight.
3. The CMP composition of claim 1 wherein the particulate abrasive material is present in an amount in the range of about 0.001 to about 6 percent by weight.
4. The CMP composition of claim 1 wherein the particulate abrasive material is selected from the group consisting of colloidal silica, fumed silica, and alpha-alumina.
5. The CMP composition of claim 1 further comprising an oxidizing agent.
6. The CMP composition of claim 5 wherein the oxidizing agent comprises at least one oxidizing agent selected from the group consisting of a hydrogen peroxide, a persulfate salt, a periodate salt, and a salt thereof.
7. The CMP composition of claim 5 wherein the oxidizing agent comprises hydrogen peroxide
8. The CMP composition of claim 5 wherein the oxidizing agent is present in an amount in the range of about 0.1 to about 6 percent by weight.
9. The CMP composition of claim 1 wherein the chelating agent comprises at least one compound selected from the group consisting of a dicarboxylic acid, a polycarboxylic acid, an aminocarboxylic acid, a phosphate, a polyphosphate, an amino phosphonate, and a phosphonocarboxylic acid, a polymeric chelating agent, and a salt thereof.
10. The CMP composition of claim 1 wherein the chelating agent comprises at least one compound selected from the group consisting of oxalic acid, malonic acid, succinic acid, citric acid, and a salt thereof.
11. A chemical-mechanical polishing (CMP) method for polishing a phase change alloy-containing substrate, the method comprising the steps of:
(a) contacting a surface of a phase change alloy-containing substrate with a polishing pad and an aqueous CMP composition, the CMP composition comprising an aqueous carrier, a particulate abrasive material, an optional oxidizing agent, and a chelating agent capable of chelating the phase change alloy, a component thereof, or a substance formed therefrom during chemical-mechanical polishing, wherein the particulate abrasive is present in the composition in an amount of not more than about 6 percent by weight; and(b) causing relative motion between the polishing pad and the substrate while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade at least a portion of the phase change alloy from the substrate.
12. The CMP method of claim 11 wherein the particulate abrasive material is present in an amount in the range of about 0.01 to about 5 percent by weight.
13. The CMP method of claim 11 wherein the particulate abrasive material is present in an amount in the range of about 0.1 to about 1 percent by weight.
14. The CMP method of claim 11 wherein the particulate abrasive material is selected from the group consisting of colloidal silica, fumed silica, and alpha-alumina.
15. The CMP method of claim 11 wherein the composition includes at least one oxidizing agent selected from the group consisting of a hydrogen peroxide, a persulfate salt, a periodate salt, and a salt thereof.
16. The CMP method of claim 11 wherein the wherein the composition includes hydrogen peroxide.
17. The CMP method of claim 11 wherein the oxidizing agent is present in an amount in the range of about 0.1 to about 6 percent by weight.
18. The CMP method of claim 11 wherein the oxidizing agent is present in an amount in the range of about 2 to about 4 percent by weight.
19. The CMP method of claim 11 wherein the chelating agent comprises at least one compound selected from the group consisting of a dicarboxylic acid, a polycarboxylic acid, an aminocarboxylic acid, a phosphate, a polyphosphate, an amino phosphonate, and a phosphonocarboxylic acid, a polymeric chelating agent, and a salt thereof.
20. The CMP method of claim 11 wherein the chelating agent comprises at least one compound selected from the group consisting of oxalic acid, malonic acid, succinic acid, citric acid, and a salt thereof.
21. The CMP method of claim 11 wherein the substrate comprises a germanium-antimony-tellurium (GST) alloy.
22. The CMP method of claim 21 wherein the substrate further comprises a liner material.
23. The CMP method of claim 22 wherein the liner material is selected from the group consisting of Ti, TiN, and a combination thereof.
24. The CMP method of claim 22 wherein the substrate further comprises a layer of silicon dioxide underneath the GST alloy and liner material.
25. The CMP method of claim 24 wherein the GST alloy and the liner material are each abraded, and the abrading is ceased at the silicon dioxide layer.
26. The CMP method of claim 11 wherein the substrate comprises indium antimonite (InSb).
Patent Application
20070178700
