Thin-film deposition apparatus using cathodic arc discharge

A thin-film deposition apparatus includes an arc vaporization portion from which charged particles of a deposition material are generated by a cathodic arc discharge, a plasma duct having a bend and guiding the charged particles from the arc vaporization portion to a substrate, a magnetic field generator for generating magnetic fields to direct the charged particles from the arc vaporization portion to the substrate, and a reflective magnetic field source installed in a convex portion of the bend of the plasma duct, for generating magnetic fields that interfere with the magnetic fields formed by the magnetic field generator so that magnetic flux lines are distributed along the plasma duct.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a thin-film deposition apparatus using a 
cathodic arc discharge, and more particularly, to a thin-film deposition 
apparatus using a cathodic arc discharge, which evaporates an arc vapor 
material from a target and guides the evaporated material to be deposited 
on a substrate. 
2. Description of the Related Art 
Generally, an arc coating method, which is a physical vapor deposition 
method of a vacuum coating method, is to coat a thin film such that a 
plasma duct is fixed at the front end of a target, and charged particles 
generated by an arc discharge, i.e., plasma, are transferred from the 
target to a substrate to be coated. The arc coating method is applied to 
manufacture of general cutting tools, molds and semiconductor devices. For 
such application, a thin-film deposition apparatus has been developed, 
which prevents macroparticles, i.e., a lump of neutral particles of a 
target material, which deteriorate the quality of the thin film generated 
by the arc coating method, from landing on the substrate. 
Referring to FIG. 1, a conventional serial thin-film deposition apparatus 
using a cathodic arc discharge includes a target 5 from which arc vapor 
materials are generated, a plasma duct 8 provided in front of the target 
5, and a cylindrical electromagnet 1 for guiding the arc vapor materials 
generated from the target 5 so that the arc vapor materials may be 
deposited on a substrate 6 facing the target 5. 
Among the arc vapor materials, i.e., electrons, target ions, neutral 
particles, macroparticles and charged macroparticles, generated from the 
target 5, the charged particles such as the electrons, target ions or 
charged macroparticles migrate along a magnetic flux line 7 by the 
electromagnet 1 to then be deposited on the substrate 6. Parts of the 
macroparticles and the neutral particles are ionized by a high-density 
plasma (electrons and ions) at the center of the electromagnet 1 to then 
be deposited on the substrate 6, and the remaining parts thereof stick to 
the inner wall of the plasma duct 8. 
However, in the aforementioned thin-film deposition apparatus, since the 
target 5 and the substrate 6 face each other, parts of non-ionized 
macroparticles may be deposited on the substrate 6, which deteriorates the 
quality of the thin film. 
To solve this problem, a rectangular thin-film deposition apparatus has 
been proposed, in which a plasma duct is bent and a magnetic field is 
distributed along the plasma duct. Referring to FIG. 2, the rectangular 
thin-film deposition apparatus includes a target 33 from which arc vapor 
materials are generated, a trigger electrode 35 contacting the target 33 
in a state where a negative voltage is applied to the target 33, a plasma 
duct 39 having a bend of approximately 90.degree., a first electromagnet 
46 disposed at the outer portion of the plasma duct 39 where the target 33 
is installed, a second electromagnet 48 disposed at the bend of the plasma 
duct 39, and a third electromagnet 50 wrapped around at the end portion of 
the plasma duct 39. 
In a state in which a voltage is applied to the target 33, if the trigger 
electrode 35 contacts the target 33, an arc is instantaneously generated, 
and arc vapor materials are generated while the generated arc stays on the 
target 33 for a predetermined time. 
If currents are applied to the first, second and third electromagnets 46, 
48 and 50, as shown in FIG. 3, magnetic flux is generated, shown by flux 
lines 40 distributed along the plasma duct 39. Thus, among the arc vapor 
materials generated from the target 33 (FIG. 2), charged particles are 
deposited on a substrate (not shown) along the magnetic flux lines 40. 
Also, parts of the neutral particles and macroparticles ionized by the 
high-density plasma are deposited to the substrate along the magnetic flux 
lines 40. Non-ionized neutral particles and macroparticles cannot reach 
the substrate and stick to the plasma duct 39 and a baffle 52 disposed at 
the inside wall of the plasma duct 39. That is to say, while most of the 
macroparticles travels around the plasma duct 39, they stick to the inner 
wall of the plasma duct 39 and the baffle 52 to then be removed. 
In the above-described rectangular thin-film deposition apparatus, the 
magnetic flux lines 40 extend outward from inside the plasma duct 39 at 
the bend of the plasma duct 39. Thus, some of the charged particles 
migrating along the magnetic flux lines 40 collide on the inner wall of 
the bend, and vanish, thereby deteriorating the deposition efficiency of 
the thin film. 
SUMMARY OF THE INVENTION 
To solve the above problems, it is an object of the present invention to 
provide a thin-film deposition apparatus using a cathodic arc discharge, 
having a reflective magnetic field source, by which magnetic flux lines 
are distributed along a plasma duct. 
To accomplish the above object, there is provided a thin-film deposition 
apparatus comprising an arc vaporization portion from which charged 
particles of a deposition material are generated by a cathodic arc 
discharge, a plasma duct having a bend and guiding the charged particles 
from the arc vaporization portion to a substrate, a magnetic field 
generator for generating magnetic fields to direct the charged particles 
from the arc vaporization portion to the substrate, and a reflective 
magnetic field source installed in a convex portion of the bend of the 
plasma duct, for generating magnetic fields that interfere with the 
magnetic fields formed by the magnetic field generator so that magnetic 
flux lines are distributed along the plasma duct. 
Here, the magnetic field generator comprises first and second magnetic 
field sources, installed near the arc vaporization portion and the 
substrate to surround the plasma duct, respectively, and an inductive 
magnetic field source provided near the bend of the plasma duct and 
diverting the charged particles. 
Also, the arc vaporization portion comprises a target coupled to a cathode 
body, a trigger electrode selectively contacting the target, to thereby 
initiate an arc discharge, an arc discharge restraining ring installed at 
the outer circumference of the target, for restraining the generated arc 
discharge, a first arc controller installed in the cathode body so that 
the position thereof can be changed with respect to the arc generating 
surface of the target, for controlling the migration of the arc, and a 
second arc controller of a ring-shape, installed at the outer 
circumference of the cathode body.

DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
As shown in FIG. 4, the thin-film deposition apparatus using a cathodic arc 
discharge according to the present invention includes an arc vaporization 
portion 100 from which charged particles of a deposition material is 
generated by the cathodic arc discharge, a plasma duct 200 having a bend 
and guiding the charged particles from the arc vaporization portion 100 to 
a substrate 1, and a magnetic field generator for generating magnetic 
fields to migrate the charged particles to the substrate 1. 
The arc vaporization portion 100 includes a target 110 coupled to a cathode 
body 113, a trigger electrode 117, selectively contacting the target 110, 
for generating an arc, an arc discharge restraining ring 400 installed at 
the outer circumference of the target 110, for restraining an arc 
discharge, and first and second arc controllers 120 and 130 for 
controlling the migration of the arc in an arc generating surface 111 of 
the target 110. 
The cathode body 113 is connected to a negative electrode 115a of an arc 
power supply 115 from which a negative voltage of 0.about.100 V with a 
current of approximately 0.about.300 A is supplied, and the target 110 is 
electrically connected to the cathode body 113. When a negative voltage is 
applied to the target 110, the trigger electrode 117 pivotably installed 
at one side of the plasma duct 200 makes contact with the target 110 and 
then loses contact therewith, so that an arc discharge occurs. 
Accordingly, arc vapor materials, e.g., charged particles, are generated 
from the surface of the target 110, i.e., from the arc generating surface 
111. Also, a cooling unit (not shown) for cooling the target 110 in the 
course of generating the charged particles, is preferably provided. 
The arc discharge restraining ring 400 is made of a ring-shaped magnetic 
material. A protrusion 141 for preventing leakage of charged particles is 
formed at an angle of approximately 0.about.90.degree. with respect to the 
arc generating surface 111. The angle between the protrusion 141 and the 
arc generating surface 111 may vary according to the kind of target 
materials. 
The first arc controller 120, disposed to the rear of the target 110 in the 
cathode body 113, controls the movement of the arc generated from the arc 
generating surface 111 of the target 110. Preferably, the first arc 
controller 120 is installed to be able to change its position with respect 
to the arc generating surface 111 of the target 110 according to the kind 
of target materials. The first arc controller 120 may be either permanent 
magnet or electromagnet. Specifically, the permanent magnet is more 
preferably used as the first arc controller 120 because it does not exert 
a thermal effect on the target 110. 
The second arc controller 130 is installed at the outer circumference of 
the cathode body 113 in a ring shape. The second arc controller 130 is an 
electromagnet in which the intensity of magnetic fields can be adjusted to 
control the movement of the arc generated from the arc generating surface 
111, and is composed of a cylindrical member 131 and a coil 132 wound 
around the cylindrical member 131. Alternatively, the second arc 
controller 130 may be a permanent magnet. 
The plasma duct 200 is bent at an angle (.theta.) of approximately 
30.about.120.degree., preferably 60.degree. with respect to a central line 
A of the target 110. 
Here, linear sections L1 and L2 of the plasma duct 200 have an enough 
length to have the neutral particles and macroparticles, which are not 
affected by the magnetic field, adsorbed into the inner wall 200a of the 
plasma duct 200, while they travel from the target 110 to the substrate 1, 
to then be removed before they reach the substrate 1. To facilitate the 
adsorption of the neutral particles and macroparticles, a baffle 250 is 
formed on the inner wall of the plasma duct 200. The baffle 250 is 
composed of a plurality of plates extended from the inner wall 200a of the 
plasma duct 200. Alternatively, the baffle 250 may be continuously formed 
in the form of spirals. 
Also, the plasma duct 200 is connected to a positive electrode 115b of the 
arc power supply 115, and a voltage higher than that of the target 110 is 
applied thereto. A flange 235 is formed at each end of the plasma duct 
200. Thus, the plasma duct 200 may be coupled to a vacuum chamber by 
screw-coupling the flange 235 to the vacuum chamber. 
The magnetic field generator includes first and second magnetic field 
sources 310 and 330, each installed around the target 110 and substrate 1 
to surround the plasma duct 200, and an inductive magnetic field source 
320 provided near the bend of the plasma duct 200. Also, the apparatus of 
the present invention includes a reflective magnetic field source 350 for 
interfering with the magnetic fields formed by the first and second 
magnetic field sources 310 and 330 and the inductive magnetic field source 
320. 
The first magnetic field source 310 guides charged particles generated from 
the arc generating surface 111 to travel along the linear section L1 of 
the plasma duct 200. The inductive magnetic field source 320 diverts the 
charged particles so that the charged particles do not collide against the 
inner wall 200a of the plasma duct 200 at the bend. Also, the second 
magnetic field source 330 guides the charged particles having passed 
through the bend to travel toward the substrate 1 along the linear section 
L2. 
Each of the first and second magnetic field sources 310 and 330 and the 
inductive magnetic field source 320 is an electromagnet which can adjust 
the magnetic field using currents, and is composed of cylindrical members 
311, 331 and 321 surrounding the plasma duct 200 and coils 315, 335 and 
325 wound around the cylindrical members 311, 331 and 321, respectively. 
Alternatively, the first and second magnetic field sources 310 and 330 and 
the inductive magnetic field source 320 may be permanent magnets. The 
magnetic fields produced by the first and second magnetic field sources 
310 and 330 and the inductive magnetic field source 320 are distributed as 
shown in FIG. 5. 
The reflective magnetic field source 350 is provided at an exterior area of 
the bend, that is, in the convex portion of the bend. If a current is 
applied to the reflective magnetic field source 350, the reflective 
magnetic field source 350 produces magnetic fields repellent against the 
magnetic fields produced by the first and second magnetic fields 310 and 
330 and the inductive magnetic field source 320 so that the magnetic flux 
lines 310 are distributed along the plasma duct 200, as shown in FIG. 6. 
The reflective magnetic field source 350 is an electromagnet for forming 
the magnetic fields according to the applied currents and is composed of a 
yoke 351 as a magnetic body having a flange at both its ends, and a coil 
355 wound around the yoke 351. Here, the reflective magnetic field source 
350 is disposed at a predetermined angle with respect to the arc 
generating surface 111 of the target 110. 
The power supply 7 supplies currents independently to the first and second 
magnetic field sources 310 and 330, the inductive magnetic field source 
320, the reflective magnetic field source 350 and the second arc 
controller 130. 
The substrate 1 is electrically connected to the negative electrode of a 
bias voltage supply 5, and a negative voltage of about 0.about.1000 V is 
applied thereto. 
Also, according to the thin-film deposition apparatus of the present 
invention, a gas such as N.sub.2, Ar or O.sub.2 is supplied to the plasma 
duct 200 through a gas tube 510 by a gas supply 500. The gas tube 510 
extends to the front part of the target 110. The supplied gas is jetted 
from the front part of the target 110 toward the arc generating surface 
111. The gas supplied into the plasma duct 200 is used for generating 
charged compound particles. For example, in the case that the target 110 
is made of Ti, the charged TiN particles are formed when the N.sub.2 gas 
is supplied from the gas supply 500 by an arc discharge in the arc 
generating surface 111 of the target 110. The generated charged TiN 
particles are guided by the magnetic field generator and deposited on the 
substrate 1. 
Now, the operation of the aforementioned thin-film deposition apparatus 
using a cathodic arc discharge according to the present invention will be 
described in more detail. When a negative voltage is applied to the target 
110 shown in FIG. 4, an arc discharge occurs while the trigger electrode 
117 makes contact with the target 110 and then loses contact therewith. 
The generated arc is restrained on the arc generating surface 111 of the 
target 110 by the arc discharge restraining ring 400 and the magnetic 
fields generated by the first and second arc controllers 120 and 130, 
thereby generating charged particles. At this time, if a current of 
triangular or sinusoidal waves is supplied to the second arc controller 
130, the arc generates uniform charged particles, i.e., ions of the target 
material, electrons and charged particles, while traveling throughout the 
arc generating surface 111. 
The charged particles guided by the first magnetic field source 310 travel 
along the linear section L1 of the plasma duct 200, and is diverted at the 
bend of the plasma duct 200 by the inductive magnetic field source 320 and 
is controlled by the second magnetic field source 330. Then, the charged 
particles are deposited on the substrate 1. 
Some of the macroparticles and neutral particles generated from the arc 
generating surface 111 together with the charged particles are ionized 
within the plasma duct 200 by collision with charged particles to then be 
deposited on the substrate 1 in the same process as that for the charged 
particles. 
Also, uncharged neutral particles and macroparticles unaffected by the 
magnetic fields move linearly and stick to the inner wall 200a or baffle 
250 near the bend to then be removed. Thus, few neutral particles and 
macroparticles reach the substrate 1. 
In this case, the reflective magnetic field source 350, as shown in FIG. 6, 
pushes the magnetic flux lines 310 of the first magnetic field source 310 
and the inductive magnetic field source 320 in the bend of the plasma duct 
200 so that the magnetic flux lines 310 are distributed along the plasma 
duct 200, thereby enhancing the transfer rate of the charged particles. 
Also, when a compound is to be coated on the substrate 1, a predetermined 
gas is supplied from the gas supply 500 and an arc discharge is made to 
occur in the arc generating surface 111 of the target 110, thereby 
producing charged compound particles. The produced charged compound 
particles are guided by the magnetic field generator to be deposited on 
the substrate 1. 
As described above, according to the thin-film deposition apparatus using a 
cathodic arc discharge of the present invention, a reflected magnetic 
field source is provided in the bend of a plasma duct so that magnetic 
flux lines are distributed along the plasma duct. Therefore, charged 
particles can reach a substrate without colliding against the inner wall 
of the plasma duct, thereby improving thin-film deposition efficiency.