Coating apparatus – Gas or vapor deposition – Work support
Reexamination Certificate
2000-02-23
2003-11-18
Hassanzadeh, Parviz (Department: 1763)
Coating apparatus
Gas or vapor deposition
Work support
C118S725000, C156S345510
Reexamination Certificate
active
06648976
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus used in a thin film formation process or in a fine processing step, etc. for producing semniconductor elements, liquid crystal display panels, solar batteries and the like.
Increasing efforts have been put forth for a plasma processing apparatus of the type referred to above so as to realize high-accuracy, high-speed, large-area, and low-damage to devices with an aim to endow the devices with a high level of function and reduce costs associated therewith. Particularly, in an attempt to obtain a film quality uniformity for a substrate in a film forming process or in an attempt to secure a size accuracy in a dry etching process employed in fine processing, precise and uniform control of a temperature of the substrate within its plane is strongly required. Therefore, a plasma processing apparatus of a model using a mechanical clamp or an electrostatic attraction electrode as structure for controlling the substrate temperature has been used for the above purpose.
A conventional plasma processing apparatus using an electrostatic attraction electrode will be described below.
By way of example of the prior art, those plasma processing apparatuses are disclosed in Japanese Laid-Open Patent Publications Nos. 63-7287, 2-7520, 3-102820, 10-189544, and 4-100257.
FIG. 5
is a sectional view of a reaction chamber of the plasma processing apparatus disclosed in Japanese Laid-Open Patent Publication No. 4-100257. This plasma processing apparatus will be discussed hereinbelow as a first example of the prior art.
In
FIG. 5
, a vacuum chamber
131
includes a gas introduction opening
140
connected to an etching gas introduction device
139
and, a vacuum discharge device
141
. An electrostatic attraction electrode
133
is set in the vacuum chamber
131
for electrostatically attracting a substrate
132
to be processed. The electrostatic attraction electrode
133
has an insulating layer
133
F (shown in
FIG. 6
) at a front face and a pair of half-round internal electrodes
142
thereinside as shown in FIG.
8
. To the electrostatic attraction electrode
133
are connected a d.c. power source
134
for the electrostatic attraction of the substrate
132
to be processed, and a high frequency power feed device
136
. The d.c. power source
134
has a switch mechanism
135
for inverting polarities. A quartz glass plate
138
is placed in the vacuum chamber
131
to confront the electrostatic attraction electrode
133
, and an ultraviolet ray source
137
is arranged outside of the vacuum chamber
131
to face the quartz glass plate
138
. A push mechanism
143
is also provided for moving up and down the substrate
132
to be processed, and to set and separate the substrate to and from the electrostatic attraction electrode
133
.
The operation of the thus-constituted conventional plasma processing apparatus
130
will be depicted below.
The substrate
132
is secured to the front face of the electrostatic attraction electrode
133
, so that the substrate is brought to a temperature optimum for plasma processing, when positive and negative voltages are applied by the d.c. power source
134
, respectively, to the pair of the internal electrodes
142
. In this state, a normal plasma process is carried out on the substrate
132
.
After completion of the plasma process, residual electric charges remain at the insulating layer at the front face of the electrostatic attraction electrode
133
although the d.c. power source
134
is shut off. As a result, the substrate
132
remains attracted to the electrostatic attraction electrode
133
. In order to stably separate the substrate
132
from the electrostatic attraction electrode
133
by the push mechanism
143
without breaking the substrate or causing similar trouble, in this case d.c. voltages with inverted polarities are applied via the switch mechanism
135
to the internal electrodes, thereby negating the residual electric charges at the substrate
132
. Thereafter, the substrate
132
is separated from the electrostatic attraction electrode by the push mechanism
143
. Then, ultraviolet rays from the ultraviolet ray source
137
, e.g. a mercury lamp, are irradiated to a surface of the insulating layer via the quartz glass plate
138
, thereby extinguishing the residual electric charges at the surface of the insulating layer. As is described in the publication, however, the residual electric charges cannot be completely removed by the simple application of d.c. voltages of inverted polarities to the internal electrodes. Moreover, if the d.c. voltages are applied for too long a time, the substrate
132
might be conversely attracted to the electrostatic attraction electrode
133
in some cases, thereby hindering the separation resulting from the push mechanism
143
and probably resulting in a problem when the substrate
132
is to be transferred to a next process. Further, the residual attraction resulting from the residual charges varies depending upon a process pressure, a kind of gas, a gas flow rate, a gas flow ratio and the other parameters as plasma process conditions, or by differences of individual substrates.
The electrostatic attraction electrode
133
is not free from dust, which will be depicted with reference to FIG.
6
. Reference numeral
133
A is a contact part at a face of the electrostatic attraction electrode continuous with an outer peripheral edge part of the substrate
132
. Reference numeral
133
B is an end part of the contact face of the electrostatic attraction electrode
133
extending perpendicular to the substrate
132
, and reference numeral
133
D is a part of the electrostatic attraction electrode
133
that is recessed and not to be in contact with the substrate
132
. A shape of the recessed part determines a contact area between the electrostatic attraction electrode
133
and the substrate
132
to enable control of a substrate temperature to achieve optimum plasma processing, although the generation and swirl of dust is not taken into account. The substrate itself contains a degree of warp from a point in time when the substrate
132
is sent into the plasma processing apparatus
130
. When the predetermined d.c. voltages are suddenly applied to attract the substrate
132
, the attraction proceeds in a manner such that the surface of the electrostatic attraction electrode
133
rubs against a warped portion of the substrate, whereby a rear-face of the substrate
132
or the electrostatic attraction electrode
133
is rubbed. Also, since a frictional resistance, when the end part
133
B attracts the substrate
132
, increases, the rear face of the substrate
132
or electrostatic attraction electrode
133
is rubbed even more. The rubbed portion of the substrate
132
or electrode
133
becomes a dust source, resulting in a decreased yield. The phenomenon is much more noticeable as the substrate is larger in size. Because of the above reasons, the conventional plasma processing apparatus
130
has a problem to be solved with regard to reliability.
The present invention is devised to solve the aforementioned problem and has for its object to provide an apparatus and a method whereby an attraction force generated by residual electric charges between a substrate and a substrate hold stage is reduced so that the substrate and the substrate hold stage can be separated from each other without any problems, irrespective of process conditions, differences of individual substrates, etc., and at the same time the generation and swirl of dust resulting from rubbing of the substrate and the substrate hold stage subsequent to the attraction is prevented.
SUMMARY OF THE INVENTION
In accomplishing these and other objects, according to a first aspect of the present invention, there is provided a plasma processing apparatus comprising:
a vacuum chamber for evacuating gas therefrom, for introducing reaction gas therein, and for generating plasma therein through high frequency power application; and
a substrate hold stage set in the
Haraguchi Hideo
Matsuda Izuru
Matsui Takuya
Yamamoto Shigeyuki
Hassanzadeh Parviz
Wenderoth , Lind & Ponack, L.L.P.
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