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Method for Controlling Composition of Compound Thin Films

IP.com Disclosure Number: IPCOM000041958D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 3 page(s) / 27K

Publishing Venue

IBM

Related People

Harper, JME: AUTHOR [+2]

Abstract

The composition of reactively deposited compounds may be controlled by using optical emission spectroscopy to continuously monitor atoms resputtered from the depositing surface and controlling the intensity of the reactive ion beam in dependence thereupon. Thin films of oxides, nitrides, carbides, and other reactively formed compounds have wide applications in semiconductor devices, optical devices, piezoelectric devices, hard coatings, low-friction coatings, and other areas. In most of these applications, control of the compound composition and structure is important to provide desired film properties, such as dielectric constant, transparency, piezoelectric coefficient, hardness, and coefficient of friction.

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Method for Controlling Composition of Compound Thin Films

The composition of reactively deposited compounds may be controlled by using optical emission spectroscopy to continuously monitor atoms resputtered from the depositing surface and controlling the intensity of the reactive ion beam in dependence thereupon. Thin films of oxides, nitrides, carbides, and other reactively formed compounds have wide applications in semiconductor devices, optical devices, piezoelectric devices, hard coatings, low-friction coatings, and other areas. In most of these applications, control of the compound composition and structure is important to provide desired film properties, such as dielectric constant, transparency, piezoelectric coefficient, hardness, and coefficient of friction. In some cases, it is desirable to synthesize a compound phase which has an intermediate stoichiometry which is not necessarily in equilibrium with either the metal target or the gas of the ion source. This article describes a method of fabricating such compound phases. Optical emission spectroscopy is used with feedback control to control the desired film composition by varying the intensity of the ion beam which provides the reactive component (e.g., O2+, N2+, etc.) to the growing film. To control the composition of the film, an optical emission spectrometer is added to a thin film deposition system to monitor the intensity of radiation from atoms sputtered from the growing film surface. Some form of ion bombardment (ideally a collimated inert ion beam but alternatively any other ion beam) is used to resputter some fraction of the growing film material. As is well established, a portion of the resputtered atoms will be in excited states and will emit radiation in the visible and near ultraviolet region, which is easily detected. An embodiment is illustrated. A vapor source 1, such as an evaporator, heats a metal 2 to generate a metal vapor flux 3 which deposits on substrate 4. Simultaneously, an ion source 5 generates an ionized flux 6 of the reactive component R (where R=O, N, H, C or S). The combination of the metal M and the reactive component R on the substrate results in the formation of a compound MxR1x, where x is controlled by the intensity of the ion flux 6. To monitor the film composition, the intensity of resputtered atoms 7 is measured by a photon counting...