Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2003-02-03
2004-08-24
Versteeg, Steven (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298230, C204S298280, C118S7230VE, C118S730000, C427S255500, C427S592000
Reexamination Certificate
active
06780290
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for forming coating films such as a transparent electrical conductive film and reflective film on a substrate surface, more specifically, a coating film forming method and device by which evenness in coating film thickness is increased.
BACKGROUND ART
A method has been conventionally used in which substrates are attached to the inside surface or outside surface of a rotatable drum-shaped substrate holder, and coating film material particles are evaporated from a coating film material placed at a position opposite to the substrates while rotating the substrate holder, whereby coating films are formed on the substrate surfaces. As a method for forming coating films, vacuum evaporation method and sputtering method have been generally used.
FIG. 6
is a schematic view showing an example of such a vacuum evaporation device. In the vacuum evaporation device shown in
FIG. 6
, a plurality of substrates
2
are attached to the inner wall surface of a rotatable drum-shaped substrate holder
1
, and while rotating the substrate holder
1
, that is, while revolving the substrates
2
, coating film material particles are evaporated from a coating film material (hereinafter, referred to as evaporating source
3
) located at the revolution central position of the substrate holder
1
, whereby coating films are formed on the surfaces of the substrates
2
.
FIG. 7
is a partial sectional view showing disposition of the substrates and substrate holder of the vacuum evaporation device shown in FIG.
6
.
Recently, formation of a coating film on a substrate having a great area has been demanded, on the other hand, uses of coating films have increased in which evenness in coating film thickness across the entire surface of the substrate with a great area is demanded. For example, such a technique achieving this is increasingly expected in uses for an electrical conductive film coated substrate, reflection preventive film coated substrate, reflective film coated substrate, a semi-transparent film coated substrate, electromagnetic shielding film coated substrate, and infrared ray shielding film coated substrate. Furthermore, these film-coated substrates are used for various displays including a liquid crystal display (LCD), organic electro luminescence (EL) display, and plasma display panel (PDP), and in addition, used for architectural members and vehicle members.
A film thickness is determined in accordance with the density on the substrate surface of coating film material particles reaching the substrate surface from the evaporating source within a unit time. The density on the substrate surface of the coating film material particles depends on the angle of inclination of the normal direction of the evaporating source surface with respect to the straight line linking the evaporating source and a specific position of the substrate surface, and depends on the distance between the evaporating source and substrate surface.
When it is assumed that the normal direction of the evaporating source surface is a solid angle of &phgr;=zero degrees, the density of coating film material particles which is evaporated in the direction of the solid angle &phgr; follows the so-called cosine rule, and is in proportion to the n-power (n≈1 to 3) of cos &phgr;.
The density of the coating film material particles to be evaporated is in inverse proportion to almost the square of the distance from the evaporating source. For example, the relationship of the density of the evaporated particles between point (a) with a d
1
distance from the evaporating source and point (b) with a d
2
distance from the evaporating source is roughly as follows:
density of evaporated particles at point (b)∝
density of evaporated particles at point (a)/(d
2
/d
1
)
2
That is, the more distant from the evaporating source, the smaller the density of evaporated particles reaching the substrate. As a result, the film thickness on the substrate surface at a distant position from the evaporating source becomes thinner than that at a position close to the evaporating source.
In order to form a coating film thickness which is even across the entire substrate surface, a film thickness correcting plate has been conventionally provided between the evaporating source and substrate. The film thickness correcting plate has a function for making the film thickness even across the entire substrate surface by eliminating density differences of evaporated particles reaching the substrate caused by the solid angle from the evaporating source and/or the distance from the evaporating source and substrate and making the density even.
FIG. 6
shows a film thickness correcting plate
5
provided for improving the film thickness distribution in the direction orthogonal to the direction of revolution of the substrates
2
disposed on the inner wall surface of the drum-shaped substrate holder
1
. The film thickness correcting plate is shaped so that, for example, as shown in the plan view of the film thickness correcting plate
5
of
FIG. 8
, the width is changed along the direction orthogonal to the direction of revolution of the substrates
2
.
In the evaporation method using the vacuum evaporation device shown in
FIG. 6
, when the film thickness correcting plate
5
is not provided, a film thickness distribution is obtained in which the film thickness of a coating film formed at the position on the substrate surface at which the solid angle &phgr; from the evaporating source
3
is great and the distance between the evaporating source
3
and substrate
2
is long becomes thinner than the thickness at a position on the substrate surface at which the solid angle &phgr; from the evaporating source
3
is small and the distance between the evaporating source
3
and substrate
2
is short.
Since the film thickness correcting plate
5
shown in
FIG. 8
is shaped so that the width decreases toward both ends, the number of evaporated particles shielded at the x portions at both ends is smaller than that shielded at the central y portion, so that the film thickness distribution of the coating films on the surfaces of the substrates
2
can compensate a deviation in the film thickness distribution occurring in the case where the abovementioned film thickness correcting plate is not provided.
In the Japanese Unexamined Patent Publication No. H11-061384, a evaporation method for forming coating films on the surfaces of the substrates
2
by using a vacuum evaporation device while revolving the substrates
2
is disclosed, and in said evaporation method, in order to make the film thickness on the surface of the substrate
2
even, for example, a film thickness correcting plate
6
a
roughly shaped into a polygon as shown in FIG.
11
(
a
) and a film thickness correcting plate
6
b
shaped into a triangle plane as shown in FIG.
11
(
b
) are used. In this publication, the substrates
2
are disposed so that the distances between the substrate
2
and the evaporating sources
3
a
and
3
b
are greatly different from each other at the entire surface of the substrate
2
, so that the shapes of the film thickness correcting plates
6
a
and
6
b
and a disposition method for the plates to compensate the film thickness distribution due to the difference between the distances from the evaporating sources
3
a
and
3
b
are described.
However, in a method in which a coating film is formed while revolving the substrates
2
by means of the vacuum evaporation method, the film thickness correcting plates
5
,
6
a
, and
6
b
used in the prior arts can improve a deviation in the film thickness distribution in the direction orthogonal to the direction of revolution of the substrates
2
, however, these cannot improve a deviation in the film thickness distribution occurring in the direction of revolution of the substrates
2
.
A deviation in the film thickness distribution due to the difference in the solid angle &phgr; from the evaporating source
3
does not occur in the direction of revolution of the substra
Ikadai Masahiro
Ogino Etsuo
Conlin, Esq. David G.
Edwards & Angell LLP
Hazzard, Esq. Lisa S.
Nippon Sheet Glass Co. Ltd.
Versteeg Steven
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