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Method for Controlling Crystal Orientation in Thin Films

IP.com Disclosure Number: IPCOM000050745D
Original Publication Date: 1982-Dec-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 45K

Publishing Venue

IBM

Related People

Cuomo, JJ: AUTHOR [+6]

Abstract

This article relates generally to the fabrication of thin films and more particularly to the control of crystal orientation in thin films.

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Method for Controlling Crystal Orientation in Thin Films

This article relates generally to the fabrication of thin films and more particularly to the control of crystal orientation in thin films.

Control of the crystal orientation of thin films is usually achieved by epitaxy, by depositing the film material on a substrate whose crystal structure determines the orientation of the growing film.

This article describes a method for controlling thin film crystal orientation without the need for epitaxy.

Crystal orientation is influenced by bombarding the growing film during deposition with a low energy ion beam. The ion bombardment influences the atomic arrangement of the growing film through any or several of the mechanisms described below. By imposing a direction on the atomic arrangement, control of the crystal orientation is achieved. The particular orientation will be determined by the ion beam direction, energy, current density and ion species.

In one embodiment, as shown in Fig. 1, a flux of atoms 1 of the desired film material is generated by a vapor source 2 and grows as a thin film 3 on a substrate 4. Simultaneously, an ion beam 5 produced by ion source 6 bombards the film at an angle 7 which determines the subsequent crystal orientation of the thin film.

Niobium (Nb) films were deposited using the arrangement of Fig. 1 with the following growth conditions:
Nb deposition rate 4 Angstroms/sec
Ar/+/ ion energy 800 eV
Ar/+/ ion current density 1.1 mA/cm/2/ at substrate Bombardment angle 28 degrees
Ar gas pressure 5-8 x 10/-5/ Torr
Substrate material: amorphous Si(3)N(4) membrane on Si substrate.

Half of the sample was shadowed from the ion beam to provide deposition with no ion bombardment. Examination by electron diffraction showed that the area of the sample deposited with no ion bombardment had some preferred orientation (texture) such that (110) planes were lying in the plane of the substrate.

The ion bombarded sample, however, showed, in addition to this texture, a preferred orientation relative to the ion beam direction. (110) planes were preferentially aligned parallel to the component of the ion beam direction in the plane of the substrate.

Amorphous carbon films were deposited by ion beam sputter deposition with simultaneous ion bombardment, as shown in Fig. 2. An argon ion beam 10 was used to sputter carbon atoms 12 from target 13 to coat substrate 14...