Niobium oxide sintered compact, sputtering target formed from said sintered compact, and method of producing niobium oxide sintered compact
The present invention provides a niobium oxide sintered compact having a composition of NbO x (2<x<2.5), and specifically provides a niobium oxide sintered compact which can be applied to a sputtering target for forming a high-quality resistance change layer for use in ReRAM. In particular, the present invention aims to provide a high-density niobium oxide sintered compact suitable for stabilizing the sputtering process.
1. A niobium oxide sintered sputtering target having a composition of NbO x (2<x<2.5) and a relative density of 90% or higher, wherein a ratio of an X-ray diffraction peak intensity from (110) plane of Nb to an X-ray diffraction peak intensity which is highest among intensities of X-ray diffraction peaks from (400) plane of NbO 2 , (001) plane of Nb 2 O 5 , and (110) plane of Nb 2 O 5 and of X-ray diffraction peaks observable within a range of 2θ from 20° to 60° is 1% or less, and wherein a ratio of an X-ray diffraction peak intensity from a Nb 12 O 29 (400) plane relative to an X-ray diffraction peak intensity from a NbO 2 (400) plane is 10% or higher.
2. The niobium oxide sintered sputtering target according to claim 1 , wherein a difference in relative densities measured at arbitrary in-plane points of the niobium oxide sintered sputtering target is 1.0% or less.
3. The niobium oxide sintered sputtering target according to claim 2 , wherein the niobium oxide sintered sputtering target has a diameter of 58 mm or more.
4. The niobium oxide sintered sputtering target according to claim 3 , wherein the niobium oxide sintered sputtering target has a resistivity of 10 Ω·cm or less.
5. A method of producing the niobium oxide sintered sputtering target according to claim 1 , wherein a NbO 2 powder and a Nb 2 O 5 powder are mixed, and the pulverized powder thereof is sintered via hot press at 950° C. to 1300° C.
6. The method of producing a niobium oxide sintered sputtering target according to claim 5 , wherein an average grain size of the NbO 2 powder is 1 to 10 μm, and an average grain size of the Nb 2 O 5 powder is 1 to 10 μm.
7. The method of producing a niobium oxide sintered sputtering target according to claim 6 , wherein the NbO 2 powder and the Nb 2 O 5 powder are mixed via wet blending.
8. The method of producing a niobium oxide sintered sputtering target according to claim 7 , wherein the NbO 2 powder has a purity of 99.9% or higher, and the Nb 2 O 5 powder has a purity of 99.9% or higher.
9. The niobium oxide sintered sputtering target according to claim 1 , wherein the niobium oxide sintered sputtering target has a diameter of 58 mm or more.
10. The niobium oxide sintered sputtering target according to claim 1 , wherein the niobium oxide sintered sputtering target has a resistivity of 10 Ω·cm or less.
11. The method of producing a niobium oxide sintered sputtering target according to claim 5 , wherein the NbO 2 powder and the Nb 2 O 5 powder are mixed via wet blending.
12. The method of producing a niobium oxide sintered sputtering target according to claim 5 , wherein the NbO 2 powder has a purity of 99.9% or higher, and the Nb 2 O 5 powder has a purity of 99.9% or higher.
13. The niobium oxide sintered sputtering target according to claim 1 , wherein the composition is NbO x (2.20≤x≤2.4).
14. The niobium oxide sintered sputtering target according to claim 1 , wherein the composition is NbO x (2.20≤x≤2.30).