FERROELECTRIC MEMORY DEVICE AND METHOD FOR MANUFACTURING FERROELECTRIC MEMORY DEVICE

Abstract

A ferroelectric memory device is equipped with a ferroelectric capacitor having a first electrode, a second electrode, and a ferroelectric layer between the first and second electrodes, and the ferroelectric memory device includes: a wiring that is connected to one of the first electrode and the second electrode, wherein the wiring includes a first wiring layer composed of titanium nitride oriented along a <111> direction, and a second wiring layer formed on the first wiring and composed of titanium aluminum nitride orientated along a <111> direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a cross-sectional view of a ferroelectric memory device in accordance with an embodiment of the invention.

FIG. 2 is a graph showing resistance values with respect to nitrogen (N) contents in wirings formed in the ferroelectric memory device in FIG. 1 and wirings formed in a comparison example.

FIGS. 3A-3D are cross-sectional views schematically showing steps of a method for manufacturing the ferroelectric memory device shown in FIG. 1.

FIGS. 4A-4D are cross-sectional views schematically showing steps of the method for manufacturing the ferroelectric memory device, succeeding FIG. 3D.

FIGS. 5A and 5B are cross-sectional views schematically showing steps of the method for manufacturing the ferroelectric memory device, succeeding FIG. 4D.

FIG. 6 is an X-ray diffraction chart of a wiring that is formed in the ferroelectric memory device shown in FIG. 1.

FIG. 7 is an X-ray diffraction chart of a wiring in accordance with a comparison example.

Claims

1. A ferroelectric memory device equipped with a ferroelectric capacitor having a first electrode, a second electrode, and a ferroelectric layer between the first and second electrodes, the ferroelectric memory device comprising: a wiring that is connected to one of the first electrode and the second electrode, wherein the wiring includes a first wiring layer composed of titanium nitride oriented along a <111> direction, and a second wiring layer formed on the first wiring and composed of titanium aluminum nitride orientated along a <111> direction.

2. A ferroelectric memory device according to claim 1, further comprising an interlayer dielectric film provided on the ferroelectric capacitor, wherein the wiring is connected to one of the first electrode and the second electrode through a contact hole formed in the interlayer dielectric film.

3. A ferroelectric memory device according to claim 1, wherein the wiring is formed in a manner to cover the ferroelectric capacitor as viewed in a plan view.

4. A ferroelectric memory device according to claim 1, wherein the titanium aluminum nitride composing the second wiring layer is expressed by Ti(1-x)AlxNy (0<x≦0.3, 0.5≦y≦1.5).

5. A method for manufacturing a ferroelectric memory device, comprising the steps of: forming, on a substrate, a ferroelectric capacitor having a first electrode, a second electrode, and a ferroelectric layer between the first electrode and the second electrode;forming an interlayer dielectric film over the substrate including the ferroelectric capacitor;forming a contact hole in the interlayer dielectric film which opens to the second electrode;forming, on the interlayer dielectric film including an interior of the contact hole, a first wiring layer composed of titanium nitride oriented in a <111> direction; andforming, on the first wiring layer, a second wiring layer composed of titanium aluminum nitride oriented in a <111> direction.

6. A method for manufacturing a ferroelectric memory device, according to claim 5, wherein the step of forming the first wiring layer includes forming a titanium layer on the interlayer dielectric film including an interior of the contact hole, and nitriding the titanium layer to form a titanium nitride layer.

7. A method for manufacturing a ferroelectric memory device according to claim 5, wherein the step of forming the first wiring layer includes applying an ammonia plasma treatment to the interlayer dielectric film including an interior of the contact hole.