Coating processes – Electrical product produced – Welding electrode
Patent
1989-01-05
1991-09-03
Silverman, Stanley
Coating processes
Electrical product produced
Welding electrode
4272481, B05D 306
Patent
active
050453483
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a thin film deposition process. It relates particularly to such a process which can be used for the thin film deposition of various dielectric layers for electronic applications.
The present invention was devised in an attempt to provide a low temperature technique that could be used for the area selective deposition of thin film dielectric materials based on oxides or nitrides. The method chosen was to irradiate a substrate body with ultraviolet light whilst passing a vapour of an organometallic compound over the substrate, such that the organometallic compound would absorb the incident light and undergo photofragmentation to form a product that would deposit on the substrate surface.
Such a process has been used already for the deposition of a wide range of metal containing compounds and it has often been necessary to use a light source producing very short wavelengths (about 200 nanometers) of radiation in order to achieve the required level of photo absorption in the available precursor materials. Such a light source is often not readily available and it is relatively costly one to provide. It may also require expensive optics or the need to eliminate the presence of oxygen from the light path.
It would therefore be more convenient to use a different type of radiation source which is more freely available and which produces a longer wavelength (for example, 250 to 400 nanometers) of radiation. However, it was found that the precursors which are commonly used for metal oxide deposition, which are alkoxide compounds, do not significantly absorb light at wavelengths greater than 200 nanometers.
An object of the present invention, therefore, was to provide precursor compounds for metal oxide deposition which compounds would have satisfactory absorption bands for light of the longer wavelength.
According to the invention, there is provided a metal oxide deposition process, in which an organometallic precursor compound is a metal alkoxy substituted beta-diketonate. In the beta-diketonate, the alpha-substitutions to the oxygen atoms may be individually selected from alkyl, fluorinated alkyl, alkoxy or aryl and the beta-substitution to the oxygen atoms is selected from hydrogen, halogen or lower alkyl.
Preferably, the compound is capable of absorbing light in the wavelength range of 240 and 400 nanometers. A more preferred range is between 250 and 300 nanometers.
The diketonate may be aluminium diisopropoxide acetyl acetonate.
According to a further aspect, there is provided a thin film deposition process in which a dielectric layer may be laid down on a substrate body surface at a comparatively low temperature, the process comprising the steps of taking a metal organic compound in vapour form the compound being capable of absorbing light in the wavelength range of 240 to 400 nanometers, heating the substrate body to a temperature below the pyrolytic decomposition temperature of the compound in the presence of the vapour, directing light of a predetermined wavelength towards the substrate to cause a photochemical fragmentation of said vapour molecules, the reaction resulting in a deposition of the required oxide on said substrate.
The metal organic compound may be a metal alkoxy substituted beta-diketonate such as aluminium diisopropoxide acetyl acetonate.
The invention further comprises an electronic device including a thin oxide layer deposited by the abovementioned process.
By way of example, a particular embodiment of the invention will now be described with reference to the accompanying drawing, in which:
FIG. 1 shows the general formula and structure of one type of organoaluminium compound of the invention,
FIG. 2 shows apparatus for carrying out the process of the invention, and,
FIG. 3 shows a substrate body supporting a deposited metal oxide layer.
In the organoaluminium compound of FIG. 1, R is preferably hydrogen but it may alternatively be halogen or a low molecular weight alkyl. The radicals R.sub.1 and R.sub.2 may be individually selected from the group of alkyl, alkoxy,
REFERENCES:
patent: 4533852 (1985-08-01), Frank et al.
patent: 4735852 (1988-04-01), Osada
Kaplan et al., CVD Deposition of Tantalum Pentoxide Films, Journal of Electrochemical Society, vol. 123, No. 10, 1976.
Brierley Crofton J.
Trundle Clive
Plessey Overseas Limited
Silverman Stanley
LandOfFree
Thin film deposition process does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thin film deposition process, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thin film deposition process will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1008085