Chemistry: electrical and wave energy – Apparatus – Vacuum arc discharge coating
Reexamination Certificate
2002-03-28
2004-02-17
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Apparatus
Vacuum arc discharge coating
C204S192380
Reexamination Certificate
active
06692623
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vacuum arc vapor deposition apparatus and a vacuum arc vapor deposition method used for forming a thin film of excellent lubricating property and hardness on such a substrate as an automobile part, machine part, machine tool, and metal mold, which includes a magnetic coil for guiding a plasma produced by a vacuum arc evaporating source to the vicinity of the substrate. More particularly, the invention relates to a vacuum arc vapor deposition apparatus for preventing degradation of the uniformity of a thickness distribution on a surface of the substrate, which is caused by the drift of the plasma in a magnetic field developed by the magnetic coil.
2. Description of the Related Art
A vacuum arc vapor deposition apparatus forms a film (thin film) on a substrate by using a vacuum arc evaporating source which vaporizes a cathode by vacuum arc discharge to produce a plasma containing a cathode material. The vacuum arc vapor deposition apparatus is advantageous in that a film forming rate is high and highly productive.
The cathode material vaporized from the cathode of the vacuum arc evaporating source contains macro particles (called droplets) of several &mgr;m or larger in addition to micro particles suitable for film formation. The macro particles fly to and attach onto the surface of the substrate, possibly damaging the adhesion property and smoothness (surface roughness) of the film.
To solve the above problems, the following two techniques are already proposed: 1) technique for transporting the plasma to the substrate after the macro particles are removed from the plasma by the utilization of a deflection magnetic field (e.g., Japanese Patent Unexamined Publication No. 2001-3160), and 2) technique to make the macro particles fine by converging the plasma by the magnetic field to increase density of the plasma (e.g., Japanese Patent Unexamined Publication No. 2000-34561).
FIG. 10
is a cross sectional view showing a vacuum arc vapor deposition apparatus which uses the technique 1) above. The vacuum arc vapor deposition apparatus includes a film forming chamber (or vacuum chamber)
2
which is vacuum discharged by a vacuum discharging apparatus (not shown). A holder
8
for holding a substrate
6
on which a film is formed is located in the film forming chamber.
In this example, a gas
4
, such as inactive gas or reaction gas, is introduced from a gas source (not shown) into the film forming chamber
2
.
Abias voltage V
B
of −50V to −500V, for example, is applied from a bias power source
10
to the holder
8
and the substrate
6
.
The film forming chamber
2
is connected to a vacuum arc evaporating source
12
through a pipe
28
(deflection pipe) bent about 90° in this example.
The vacuum arc evaporating source
12
includes a cathode
14
mounted on an end plate
29
of the pipe
28
with an insulating material
20
inserted there between. The cathode
14
is vaporized through vacuum arc discharge occurring between the cathode
14
and the pipe
28
serving also as an anode to produce a plasma
18
containing a cathode material
16
. An anode electrode may be individually provided. Here, the “cathode material” means material forming the cathode
14
. An arc discharging voltage is applied from an arc power source
22
to between the cathode
14
and the pipe
28
. The vacuum arc evaporating source
12
includes a known trigger mechanism, a water cooling mechanism and the like. Those mechanisms are not illustrated in the specification, for simplicity.
A plurality of magnetic coils
24
are provided around an outer periphery of the pipe
28
. The magnetic coils generate a magnetic field for deflecting the plasma
18
produced by the vacuum arc evaporating source
12
, and guides (transports) the plasma
18
to the vicinity of the substrate
6
in the film forming chamber
2
. Some of magnetic field lines
26
generated by the magnetic coils
24
are roughly illustrated in the figure, and as shown, those magnetic field lines extend substantially along an inner surface of the pipe
28
. Those magnetic coils
24
are connected in series, and fed with a coil current I
c
for generating the magnetic field from a coil power source
30
.
The plasma
18
produced by the vacuum arc evaporating source
12
is bent to substantially along the magnetic field lines
26
and transported to the substrate
6
. The macroparticles emitted from the cathode
14
are electrically neutral or negatively charged in the plasma
18
. A mass of the macro particle is considerably large. Accordingly, those particles go straight irrespective of the magnetic field, and hit the inner wall of the bent pipe
28
and hence fail to reach the substrate
6
. As a result, the plasma
18
little containing the macro particles is led to the vicinity of the substrate
6
. Thus, it is prevented that the macro particles attach to the substrate
6
. The apparatus which has the magnetic coils
24
, pipe
28
and coil power source
30
(coil power source
40
in
FIG. 1
) as mentioned above is also called a magnetic filter where attention is put on the macro-particle removing function.
Ions (i.e., ionized cathode material
16
) in the plasma
18
thus transported to near the substrate
6
are attracted to the substrate
6
under the bias voltage V
B
and the like, and deposited on the surface of the substrate to form a thin film on the substrate. When a reaction gas which reacts with the cathode material
16
to form a chemical compound is used for the gas
4
, a compound thin film may be formed.
When an electron is transported in a uniform magnetic field, as well known, the electron makes a gyrating movement such that it winds round the magnetic field lines, under Lorentz forces given by the following equation 1. In the equation,
q
is a charge,
v
is an electron velocity, and
B
is a flux density (The same rule applies correspondingly to the description to follow.).
F=qvB
[Equation 1]
Accordingly, in a uniform magnetic field, electrons emitted from two positions P and Q shown in
FIG. 11
move along magnetic field lines
26
uniformly distributed, reach the substrate
6
, and are incident on positions near positions P
1
and Q
1
corresponding to the positions P and Q.
Actually, a magnetic field developed by the magnetic coils
24
is not uniform and has gradients of a magnetic field without exception. For drift of charged particles, such as electrons, in a magnetic field having gradients, reference is made to “Newest Plasma Production Technique”, by Yoshinobu Kawai, published by IPC corporation on Aug. 5, 1991, pages 12 to 21. As described, the charged particle drifts at a drift velocity V
D
given by the following equation 2. In the equation,
&mgr;
is magnetic permeability, ∇B is a gradient (vector) of the magnetic field, and Bv is a magnetic field (vector), and other things are the same as mentioned above. ∇ is a nabla or Hamiltonian operator.
V
D
=−&mgr;(∇
B×Bv
)/(
qB
2
) [Equation 2]
The gradient of the magnetic field will be discussed by using an apparatus which transports the plasma
18
by use of the deflection magnetic field as shown in
FIG. 10
(or
FIG. 1
to be described later).
A case where the magnetic coil
24
and the pipe
28
are circular in cross section is shown in
FIGS. 12
to
18
. In
FIGS. 12
to
15
, the cathodes
14
a
and
14
b
are simply represented by two positions “P” and “Q” (the same thing is correspondingly applied to the illustrations of
FIGS. 19
to
21
to be described later). In
FIGS. 16
to
18
, the cathodes
14
a
and
14
b
are specifically illustrated (the same thing is correspondingly applied to the illustrations of
FIGS. 22 and 23
to be described later and
FIGS. 2
to
7
).
In this case, the nature of the circular magnetic coils
24
gives the magnetic field in the pipe
28
such a gradient ∇ B as shown in
FIG. 14
that, an intensity of the magnetic field is lowest at the
Finnegan Henderson Farabow Garrett & Dunner LLP
McDonald Rodney G.
Nissin Electric Co. Ltd.
LandOfFree
Vacuum arc vapor deposition apparatus and vacuum arc vapor... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vacuum arc vapor deposition apparatus and vacuum arc vapor..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vacuum arc vapor deposition apparatus and vacuum arc vapor... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3351162