Coating apparatus – Gas or vapor deposition – Crucible or evaporator structure
Patent
1986-01-28
1987-10-20
Silverberg, Sam
Coating apparatus
Gas or vapor deposition
Crucible or evaporator structure
427250, C23C 1424
Patent
active
047006609
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates generally to the art of applying coatings to surfaces, and more particularly to an evaporator for vacuum depositing films.
BACKGROUND OF THE INVENTION
A major demand imposed on evaporators for vacuum film depositing is to obviate wastage of the evaporant failing to deposit on the substrate by ensuring its revaporization and to provide film thickness uniformity within a wide range of materials deposited on substantial surface areas of substrates.
Films can be deposited more uniformly by spacing the substrate at a considerable distance from the evaporator, whereas for reducing losses of the evaporant it is possible to recover the vaporized evaporant material failing to fall on the substrate.
By way of example, there is known a device for vacuum deposition of metal films on a substrate, which comprises a crucible with a substrate spaced therefrom both surrounded by a chamber serving to collect the evaporant failing to impinge onto the substrate. On terminating the process of vacuum plating, the evaporant deposited on the walls of this chamber is removed therefrom to be recharged to the crucible for revaporization. However, inherent in this device is a disadvantage of non-uniform thickness of the film deposited, because the distance from the crucible to the substrate is confined by the dimensions of the chamber. In addition, the evaporant material scraped off the walls of the chamber for reuse is contaminated by foreign impurities. Among the sources of such impurities are both the material of the chamber mixing with deposited evaporant during chamber walls cleaning, and residual gases of the vacuum chamber tending to condense on the walls of the chamber. The condensed residual gases are of considerable size since the substrate is rather remote from the crucible. Another disadvantage resides in much labour required for cleaning the chamber.
The process of cleaning the chamber can be made less labour-consuming by revaporization of the material condensed on the walls of the evaporant collecting chamber, which is offered by an apparatus for vacuum depositing disclosed in Japanese Application No. 57-134555, Int. Cl. C 23 C 13/00, 13/08, published Aug. 19, 1982. This apparatus comprises arranged in vacuum a vapor source in the form of a crucible having arranged thereabove a vapor collecting chamber which encloses the flow of vaporant traveling toward the substrate. This collecting chamber can be heated to the temperature of vaporant in the crucible or to a temperature sufficiently high for revaporizing the material deposited on the walls of the collecting chamber. Therefore, the evaporant material which does not impinge on the substrate tends to condense on the walls of the collecting chamber and thanks to high temperature of these walls is revaporized therefrom.
This apparatus also fails to ensure high purity of the film being deposited due to excessive liberation of gas from the collecting chamber because of the high temperature to which it is heated and its large size determined by the distance from the crucible to the substrate. For the same reason, the substrate is likewise heated to an intolerably high temperature by the heat radiating from the collecting chamber. Also, considerable losses of evaporant take place due to escape thereof through clearances between the crucible, collecting chamber and substrate.
Wastage of the evaporant material can be minimized, when the temperature of the collecting chamber is lowered. An attending advantage is associated with less pronounced overheating of the substrate. These advantages are materialized in a liquid phase regeneration device for vacuum deposition of films (cf., Japanese Application No. 57-155368, Int. Cl. C 23 C 13/00, 13/08, published Sept. 25, 1982) which comprises a crucible containing an evaporant with a collecting chamber arranged thereabove around the flow of vapor moving toward the substrate. The lower edge of the chamber occupies the upper part of crucible interior. During film deposition the vapor colle
REFERENCES:
patent: 3572672 (1971-03-01), Harel
patent: 4125086 (1978-11-01), Vig et al.
patent: 4412508 (1983-11-01), Ney et al.
Grant, Julius, Hackh's Chemical Dictionary, McGraw-Hill (.COPYRGT.1972), p. 115.
Handbook Of Thin Film Technology, Leon I. Maissel And Reinhard Glang, pp. I-36 Through I-68.
Levchenko Georgy T.
Radzikovsky Alexandr N.
Kievsky Politekhnichesky Institut
Owens Terry J.
Silverberg Sam
LandOfFree
Evaporator for depositing films in a vacuum does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Evaporator for depositing films in a vacuum, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evaporator for depositing films in a vacuum will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1606173