# US 9,437,486 B2 · Sputtering target

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- Number: US 9,437,486 B2
- Document ID: US9437486B2
- Status: Granted
- Kind: B2
- Application number: 13/280,873
- Filed: 2011-10-25
- Published: 2012-02-16
- Granted: 2016-09-06
- Earliest claimed: 1998-06-29
- Assignees: Kabushiki Kaisha Toshiba
- Applicants: Koichi Watanabe; Yasuo Kohsaka; Takashi Watanabe; Takashi Ishigami; Yukinobu Suzuki; Naomi Fujioka
- Inventors: Koichi Watanabe; Yasuo Kohsaka; Takashi Watanabe; Takashi Ishigami; Yukinobu Suzuki; Naomi Fujioka
- Web page: https://patentgrep.com/patent/US9437486B2

## CPC

- H10W 20/033: {in openings in dielectrics}
- C23C 14/3414: {Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

A sputtering target contains high purity Nb of which Ta content is 3000 ppm or less and oxygen content is 200 ppm or less. Dispersion of the Ta content in all the sputtering target is within ±30% as a whole target. Dispersion of the oxygen content is within ±80% as a whole target. According to such sputtering target, an interconnection film of low resistivity can be realized. In addition, each grain of Nb in the sputtering target has a grain diameter in the range of 0.1 to 10 times an average grain diameter and ratios of grain sizes of adjacent grains are in the range of 0.1 to 10. According to such sputtering target, giant dust can be largely suppressed from occurring. The sputtering target is suitable for forming a Nb film as liner material of an Al interconnection.

## Claims

### Claim 1

A method for manufacturing an Al interconnection having a dual damascene structure, comprising:
processing chemically a niobium oxide containing concentrate of which a Ta content is 3000 ppm or less to obtain a high purity niobium oxide,
reducing the high purity niobium oxide by a thermite reduction method due to Al to obtain a Nb raw material,
melting the Nb raw material at least two times by an electron beam melting to obtain a Nb ingot containing Ta in a range of 550 to 1000 ppm and oxygen in a range of 10 to 100 ppm as impurities;
plastic working the Nb ingot at a working rate in a range of 55 to 95% so as to disperse the Ta and the oxygen in the Nb ingot uniformly, to obtain a Nb plate in which a dispersion of the Ta content is within 15% and a dispersion of the oxygen content is within 30%,
recrystallizing the Nb plate by heat-treating at a temperature in a range of from 800 to 1300° C. for one hour or more, to obtain the Nb plate including Nb grains having an average grain diameter in a range of from 10 to 75 μm, wherein each of the Nb grains has a grain diameter in a range of 0.1 to 10 times the average grain diameter, and a grain size ratio of adjacent grains in the Nb grains is in a range of 0.5 to 1.5;
machining the recrystallized Nb plate into a desired shape;
bonding the machined Nb plate with a backing plate made of Al or an Al alloy by hot-pressing at a temperature in a range of 400 to 600° C. while maintaining the average grain diameter of the Nb grains in the Nb plate, to prepare a Nb sputtering target;
preparing an insulating film having a trench;
forming a Nb liner film in the trench by sputtering the Nb sputtering target; and
forming an Al interconnection film on the Nb liner film, wherein the Al interconnection film is composed of Al or Al alloy, and a resistivity of the Al interconnection film is 4 μΩcm or less.

### Claim 2 (depends on 1)

The manufacturing method as set forth in claim 1,
wherein the Nb liner film is formed along an inner wall of the trench, and the Al interconnection film is filled in the trench having the Nb liner film formed along the inner wall.

### Claim 3 (depends on 1)

The manufacturing method as set forth in claim 1, wherein the average grain diameter of the Nb grains in the Nb sputtering target is in a range of 10 to 50 μm.

### Claim 4 (depends on 1)

The manufacturing method as set forth in claim 1, wherein a dispersion of the grain size ratio of the adjacent grains in the Nb sputtering target is within 30%.