Chemistry: electrical and wave energy – Processes and products – Coating – forming or etching by sputtering
Reexamination Certificate
2001-08-28
2004-03-16
McDonald, Rodney G. (Department: 1753)
Chemistry: electrical and wave energy
Processes and products
Coating, forming or etching by sputtering
C204S298060, C204S298110, C204S298140
Reexamination Certificate
active
06706155
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of The Invention
The present invention relates to the technological field of sputtering apparatus, and particularly to improvement of step coverage of sputtering apparatus.
2. Description of Related Art
A related sputtering apparatus is shown by numeral
110
in FIG.
6
.
This sputtering apparatus
110
has a vacuum chamber
112
, with a wafer stage
114
fitted onto a bottom wall of the vacuum chamber
112
in such a manner as to be insulated from the wall surface of the vacuum chamber
112
.
A ceiling plate
113
is fitted to the ceiling side (of the vacuum chamber
112
via an insulating member
118
. A magnet
119
is located on the ceiling plate
113
via an insulating member (not shown) and a target
120
is located at an inside surface of the vacuum chamber
112
at the surface on the opposite side to the magnet
119
.
A cooling equipment
115
and a substrate table
116
are mounted, in order, on the wafer stage
114
. A chucking electrode (not shown) is located inside the substrate table
116
. The inside of the vacuum chamber
112
is evacuated and a substrate
117
is mounted on the substrate table
116
. When a voltage is then applied to the chucking electrode, the substrate
117
is electrostatically chucked to the surface of the substrate table
116
.
A sputtering power supply
125
is connected to the target
120
and the vacuum chamber
112
is connected to earth potential. After the inside of the vacuum chamber
112
is evacuated and the substrate
117
is electrostatically chucked onto the substrate table
116
, a sputtering gas is introduced into the vacuum chamber
112
and the sputtering power supply
125
is activated. When a negative voltage is then applied to the target
120
, a plasma is generated in the vicinity of the surface of the target
120
as a result of electrons being captured by magnetic lines of force of the magnet
119
. When this plasma is incident to the target
120
, the material making up the target
120
flies off from the surface of the target
120
as sputtering particles.
At the sputtering apparatus
110
, a cylindrical deposition preventing plate
111
is located within the vacuum chamber
112
and is fixed to the surface of the inner wall of the vacuum chamber
112
. The deposition preventing plate
111
is also positioned at earth potential together with the vacuum chamber
112
because the vacuum chamber
112
is located at earth potential.
A negative voltage is applied to the wafer stage
114
, and the substrate
117
is positioned at negative potential. Electrons in the plasma are chucked towards the deposition preventing plate
111
, and sputtering particles having a positive potential flying off from the target
120
are chucked towards the substrate
117
. As a result, sputtering particles fly off in a direction along a central axis of the deposition preventing plate
111
within the deposition preventing plate
111
; and a thin film is formed at the surface of the substrate
117
upon the sputtering particles reaching the surface of the substrate
117
.
A water path
123
is provided within the cooling equipment
115
. After a thin film is formed to a predetermined thickness at the surface of the substrate
117
, cooling water flows in the water path
123
. After the substrate
117
is cooled, the substrate
117
is carried outside of the vacuum chamber
112
. When an as-yet unprocessed substrate is introduced into the vacuum chamber
112
, the thin film forming operation can then be repeated.
The sputtering particles do not become attached to the surface of the inner wall of the vacuum chamber
112
because the deposition preventing plate
111
is located at the periphery of the flight path of the sputtering particles. Therefore, when a multiplicity of substrates
117
are processed and the inside of the vacuum chamber is cleaned, the deposition preventing plate
111
is extracted; and thin film that has become attached to the inner peripheral surface of the deposition preventing plate
111
is cleaned and removed.
Therefore, with the deposition preventing plate
111
of the above configuration, the prevention of thin film becoming attached to the surface of the inner wall of the vacuum chamber
112
is halted when the deposition preventing plate
111
is extracted, and this cannot be said to improve the performance of the sputtering apparatus
110
.
In recent years, attempts have been made to improve the step coverage of thin films formed at the surface of the substrate
117
by applying a voltage to the deposition preventing plate
111
, but sufficient step coverage has yet to be obtained
As the present invention sets out to resolve the aforementioned problems of the related art, it is the object of the present invention to provide a sputtering apparatus capable of forming a thin film with a good step coverage.
SUMMARY OF THE INVENTION
In order to resolve the aforementioned problems, a sputtering apparatus comprises a vacuum chamber, a target positioned within the vacuum chamber, a substrate table located within the vacuum chamber at a position facing the target, an anode electrode surrounding the periphery of a portion, on the target side, of flying space where sputtering particles flying off from the target are flying, of space between the target and the substrate table, and an earth electrode encompassing a portion, of the remaining portion of the flying space, between the anode electrode and the substrate table. The earth electrode and the anode electrode are electrically insulated from each other and are subjected to the application of different voltages.
The sputtering apparatus of the present invention has a power supply, wherein the vacuum chamber and the earth electrodes are connected to earth, and the power supply applies a positive voltage to the anode electrode.
With this sputtering apparatus, a substrate table is mounted on a wafer stage; and a negative voltage can be applied to the wafer stage.
Further, with this sputtering apparatus, the earth electrode can be divided into first and second earth electrodes, with a gap being formed between the first and second earth electrodes.
Moreover, with the sputtering apparatus of the present invention having the target located at the top and the substrate table located below the target, the anode electrode can be formed a tubular shape, and a flange can be provided at the outer periphery of one end of the anode electrode, with a conductive terminal member insulated electrically from the vacuum chamber projecting at the inside of the vacuum chamber, and at the anode electrode, the flange mounting the terminal member, and the opening on the opposite side to the opening provided with the flange facing the substrate table.
Still further, in a thin film manufacturing method of the present invention where a target is positioned in a vacuum chamber, the vacuum chamber is connected to earth potential, a negative voltage is applied to the target so that a plasma is formed in the vicinity of the surface of the target, and sputtering particles flying off from the target reach a substrate positioned with a surface facing the target so as to form a thin film on the surface of the substrate, with an anode electrode surrounding the periphery of a portion, on the target side, of flying space where sputtering particles flying off from the target are flying, of space between the target and the substrate table, comprising a step of connecting the potential of the periphery surrounding the substrate to earth potential, applying a positive voltage to the anode electrode, and sputtering the target.
In the present invention, a negative bias voltage is applied to the substrate.
When the present invention is configured in the above manner, when the space between the target and the substrate is taken to be the flying space of the sputtering particles, the potential of the vacuum chamber is connected to earth potential; and a positive voltage can be applied to the anode electrode encompassing the portion of this flying space which is on the target side.
Kondo Tomoyasu
Morimoto Naoki
Nagashima Hideto
Armstrong, Kratz, Quintos Hanson & Brooks, LLP.
McDonald Rodney G.
Qlvac, Inc.
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