Chemistry: electrical and wave energy – Apparatus – Coating – forming or etching by sputtering
Reexamination Certificate
2000-02-01
2002-01-29
Huff, Mark F. (Department: 1756)
Chemistry: electrical and wave energy
Apparatus
Coating, forming or etching by sputtering
C204S298080, C204S298160, C204S298110, C204S298190
Reexamination Certificate
active
06342139
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a sputtering system which is a kind of thin film deposition system.
The sputtering system is a system for depositing a thin film by a method comprising generating plasma by producing gas discharge generally in a low vacuum atmosphere and making cations of the plasma collide against a target set on a negative electrode that is called a sputtering electrode, so that particles sputtered by the collision are deposited onto the substrate. This sputtering system, in which the control of thin film composition and the operation of the system are relatively easy, has been used widely for a film deposition process.
FIG. 7
shows the construction of a conventional magnetron sputtering system. Referring to
FIG. 7
, reference numeral
101
denotes a vacuum vessel,
102
denotes an evacuation port, through which evacuation is made by a vacuum pump (not shown), and
103
denotes a movable valve, which allows evacuation conductance to be controlled. The object denoted by numeral
104
is a main valve.
Numeral
105
denotes a gas inlet tube directed toward the inside of the vacuum vessel
101
, and
106
denotes a gas flow rate controller attached to the gas inlet tube
105
. Numeral
107
denotes discharge gas, which is introduced into the vacuum vessel
101
through the gas inlet tube
105
, and argon gas is normally used. Numeral
108
denotes a gas inlet valve.
Numeral
109
denotes a target,
110
denotes a sputtering electrode,
111
denotes a power supply for discharge, and
112
denotes a magnet, which is arranged at the rear surface side of the target
109
. Numeral
113
denotes a substrate holder disposed within the vacuum vessel
101
so as to be opposed to the front surface of the target
109
, and a substrate
114
for depositing a thin film is set on the substrate holder
113
. The object denoted by
118
is an insulator.
With respect to the sputtering system constructed as shown above, its operation is described below. First, the interior of the vacuum vessel
101
is evacuated to about 10
−7
Torr through the evacuation port
102
by the vacuum pump. Next, the discharge gas
107
is introduced into the vacuum vessel
101
via the gas inlet tube
105
connected to one end of the vacuum vessel
101
, so that the internal pressure of the vacuum vessel
101
is maintained at about 10
−-3
to 10
−2
Torr. In this state, power is supplied from the DC or high-frequency discharge power supply
111
to the sputtering electrode
110
to which the target
109
is mounted, so that an electric field is formed. As a result, by the action of the electric field in combination with a magnetic field due to the magnet
112
set on the rear side of the target
109
, ring-shaped plasma due to discharge occurs near the surface of the target
109
, giving rise to a sputtering phenomenon. Thus, by sputtered particles emitted from the target
109
, a thin film is deposited on the substrate
114
set on the substrate holder
113
.
In recent years, as the thin film material progressively advances to higher functions, there is a growing need for film deposition under low gas pressure. In the case of film deposition under about 10
−3
Torr or lower pressure, the above magnetron sputtering system would be problematic in discharge stability, so would be substantially difficult to achieve the film deposition.
Therefore, as described in Japanese Laid-open Patent Publication No. 6-041739, there has been an attempt made in which a helical coil connected to a high-frequency power supply is provided between a substrate and a target of the magnetron sputtering system so as to stabilize the discharge under low g as pressure. The coil generates an inductive magnetic field when high-frequency power is applied thereto.
FIG. 8
shows a schematic construction of a magnetron sputtering system in which this helical coil is additionally provided. Referring to
FIG. 8
, numeral
121
denotes the helical coil. Numeral
122
denotes a coil-use high-frequency power supply connected to the helical coil
121
. T his magnetron sputtering system operates generally in the same way as the foregoing magnetron sputtering system, but differs therefrom in that power is supplied to the sputtering electrode
110
while high-frequency power is supplied to the helical coil
121
with the coil-use high-frequency power supply
122
.
As to dry etching systems, on the other hand, there have been devised some forms of discharge suitable for discharge at low gas pressure by other methods. As an example, the present applicant has previously proposed a dry etching system. In this dry etching system, as shown in
FIG. 9
, with a flat type antenna
131
disposed outside a vacuum vessel
101
, a high-frequency power of about 50 MHz-3 GHz is applied to this flat type antenna
131
with a high-frequency power supply
135
, and an electromagnetic wave generated by the flat type antenna
131
is introduced into the vacuum vessel
101
through an electromagnetic-wave inlet window
134
. Also, high-frequency power is supplied from a high-frequency power supply
132
to the substrate
114
, and etching gas
133
is introduced into the vacuum vessel
101
through the gas inlet tube
105
, by which plasma is formed inside the vacuum vessel
101
under low gas pressure.
However, with such a constitution as shown in
FIG. 8
, since the helical coil
121
is set in the vacuum vessel
101
, the coil material is sputtered to form in-film impurities. Also, if the coil material is prevented from being sputtered, film would be deposited on the coil, resulting in an unstable plasma. This would make a dust generating source or cause the issue of unstable plasma, disadvantageously.
Also, with such a constitution as shown in
FIG. 9
, in applications to a sputtering system, especially when an electrical conductor film is formed, there would occur an issue unique to a film deposition system such as a sputtering system in which the conductor film would be deposited onto the electromagnetic-wave inlet window
134
, so that electromagnetic waves could no longer be radiated into the vacuum vessel
101
.
In view of these issues of the prior art, an object of the present invention is to provide a sputtering system which is capable of maintaining discharge stably even under low gas pressure and thus forming a high-quality film.
SUMMARY OF THE INVENTION
In accomplishing these and other aspects, according to a first aspect of the present invention, there is provided a sputtering system comprising: a vacuum chamber; and a sputtering electrode provided in the vacuum chamber. A target is supported on the sputtering electrode with a front surface of both the target and a substrate disposed in the vacuum chamber arranged so as to be opposed to each other. In addition, a high-frequency or DC power source is provided for supplying a high-frequency or DC power to the sputtering electrode to generate plasma on the target, and an antenna is provided for generating an electromagnetic wave which is provided outside the vacuum chamber and near the target. Finally, an electromagnetic-wave inlet window is provided for introducing into the vacuum chamber an electromagnetic wave generated from the antenna which is provided in a wall of the vacuum chamber.
Thus, the sputtering system is capable of maintaining discharge stably, and so forming a high quality film, even under low gas pressure by introducing into the vacuum chamber the electromagnetic wave derived from the antenna without causing occurrence of impurities by the antenna being sputtered or causing unstable plasma due to film deposition.
According to a second aspect of the present invention, there is provided a sputtering system according to the first aspect, wherein the electromagnetic-wave inlet window is disposed on a side and rear of the target in the wall of the vacuum chamber. Thereby, the amount of film deposition onto the inner surface of the electromagnetic-wave inlet window can be lessened, and a stable film deposition can be achieved even dur
Aokura Isamu
Okumura Tomohiro
Suzuki Naoki
Chacko-Davis Daborah
Huff Mark F.
LandOfFree
Sputtering system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Sputtering system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Sputtering system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2845963