Coating apparatus – Condition responsive control
Reexamination Certificate
2000-04-07
2001-05-22
Bueker, Richard (Department: 1763)
Coating apparatus
Condition responsive control
C118S712000, C118S725000, C118S726000
Reexamination Certificate
active
06235118
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relate to a method for forming a film of ultra-fine particles, and an apparatus for the same, and more particularly to a method for forming a film of ultra-fine particles and an apparatus for the same by which a film of ultra-fine particle is formed on an inner wall surface of a hole smaller than 2 &mgr;m in diameter, and having an aspect ratio of larger than one.
2. Description of the Prior Art
Among methods for forming a thin film, there are a sputtering method, a deposition method, a physical vapor deposition method (PVD) such as an ion-beam deposition method, a chemical deposition method (CVD), a plating method and any other liquid phase film-forming method. In the physical vapor deposition method, atoms or molecules as film-forming material move in a straight line, from the generating source. Accordingly, positions on the base body on which a thin film should be formed, depend on the geometrical arrangement or mechanical arrangement of the generating source of the film forming material and of the base body. It is almost impossible to form a uniform film on an inner wall surface of a fine hole of large aspect ratio or a groove of the similar size, in the base body, since the straight flight line of the film forming material does not reach there. On the other hand, it is possible to form a relatively uniform film on the above fine hole or groove, by the CVD method or liquid phase film forming method. However, it is unavoidable that any impurities are mixed into the formed thin film.
Among methods for forming thin films of ultra-fine particles, there are a so-called “Gas Deposition method” or “Jet Printing method” in which a transport pipe and jet gas for transport are used to form locally a thin film, and “Cluster ion beam method” in which ionized grain beams are used. However, also in these methods, the film forming condition is limited by the geometrical or mechanical arrangement of the generating source of the film forming material and of the base body. Further, there is the method in which ultra-fine particles are sinked or precipitated from the liquid phase. However, in this method, a surface tension acts between the inner wall surface of the hole or groove, and so it is difficult to form uniformly a thin film. Accordingly, this method cannot be widely used.
As above described, it is difficult to form a uniform thin film without impurity, on the inner wall surface of the fine hole or groove, by the above Prior Art thin film forming methods. According, in one case, a high-integrated semiconductor device, in which via holes are aspect ratio of larger than one, and a line width equal to a fraction of a &mgr;m or smaller is subjected to various limitation of manufacture it difficult to form a uniform film of activated metal on the inner wall surface of fine holes on a catalyst carrier of high performance.
As an example, a base body
5
in which fine holes or grooves are made, is schematically shown in
FIG. 1. A
film
2
of silicon oxidate as insulator is formed on a silicon substrate
1
. Another film
3
of aluminium is formed on the film
2
. A fine groove
4
is formed in the film
2
, and it is filled with aluminium. A second silicon oxidate film
5
is formed on the aluminium film
3
. A second groove
6
is made in the film
5
, and its bottom is the upper surface of the film
3
. A via hole
7
with the bottom which is the upper surface of the film
3
, is made in the groove
6
. The groove
6
is 0.1 &mgr;m in width, and 0.3 &mgr;m in depth. The via hole
7
is 0.2 &mgr;m in diameter, and 1 &mgr;m in depth. The aspect ratio of the groove
6
is equal to 3, and that of the via hole
7
is equal to 5. It is difficult to form a thin film of metal, or particularly, high-melting metal or ceramics, onto the inner wall surfaces of the groove
6
and via hole
7
, by the Prior Art CVD method.
SUMMARY OF THE INVENTION
Accordingly, it is an object of this invention to provide a method of forming a thin film and an apparatus for the same in which a uniform thin film can be formed on an inner wall surface of a fine hole with a diameter of 2 &mgr;m or smaller in diameter, and having aspect ratio of larger than one, or a groove of the similar size, regardless of any geometrical or mechanical arrangement of a generating source of film forming material, and of a base body to be film-formed, and in which impurity is not mixed into the thin film in contrast to the Prior Art CVD method and liquid phase film forming method.
In accordance with an aspect of this invention,
A method of forming a thin film of ultra-fine particles comprising the steps of: arranging a base under vacuum, said base body having a hole with bottom, a through hole, smaller than 2 &mgr;m in diameter and having aspect rtio of larger than one, or a groove having the similar size; applying aerosol of ultra-fine particles of smaller than 0.1 &mgr;m in diameter onto an inner wall surface of said hole, said through hole or said groove, said aerosol dispersed and floating in gas under a pressure higher than 10
2
Pa; and diffusing and adsorbing said aerosol onto said inner wall surface.
In accordance with another aspect of this invention,
An apparatus for forming a film of ultra-fine particles comprising: an aerosol generating apparatus in which ultra-fine particles of smaller than 0.1 &mgr;m in diameter are made from evaporated material, and are dispersed and floating in gas; a holding mechanism for holding a base body having a hole with a bottom, or through hole, said hole or said through hole formed through with a diameter smaller than 2 &mgr;m and an aspect ratio of larger than one; or a groove, a film of ultra-fine particles being formed on said base body; a heating mechanism for heating said base body; a pressure-adjusting mechanism for maintaining said aerosol at a predetermined pressure; a thin-film forming container containing at least said holding mechanism; and a vacuum system connected to said film forming container;
The foregoing and other objects, features, and advantages of the present invention will be more readily understood upon consideration of the following detailed description of the preferred embodiment of the invention, taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 3840391 (1974-10-01), Spitz et al.
patent: 4332838 (1982-06-01), Wegrzyn
patent: 4405658 (1983-09-01), Young
patent: 5456945 (1995-10-01), McMillan et al.
patent: 5540959 (1996-07-01), Wang
Bueker Richard
Piper Marbury Rudnick & Wolfe
Vacuum Metallurgical Co., Ltd.
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