Electric heating – Metal heating – By arc
Reexamination Certificate
2002-10-29
2004-07-27
Fuqua, Shawntina (Department: 3742)
Electric heating
Metal heating
By arc
C219S121580, C219S121410, C156S345350, C156S345470, C204S298210, C204S298360, C392S416000, C392S418000
Reexamination Certificate
active
06768079
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a susceptor with a built-in plasma generation electrode and a manufacturing method therefor. In particular, it relates to a susceptor with a built-in plasma generation electrode that has excellent corrosion resistance and plasma resistance, that can enable uniform etching of plate specimens, deposition of film and so forth, and that has excellent durability, and a manufacturing method for a susceptor with a built-in plasma generation electrode that enables a susceptor with a built-in plasma generation electrode to be manufactured economically and with a high yield.
2. Description of the Related Art
In recent years, in plasma etching apparatus, plasma CVD apparatus and the like used in manufacturing processes of semiconductor devices such as ICs, LSIs and VLSIs, in order to perform film deposition uniformly on each wafer by plasma etching or plasma CVD, these wafers (plate specimens) are mounted onto a specimen support (pedestal) called a susceptor, and prescribed processing is carried out.
Because this susceptor must withstand use within plasma and use at high temperatures, the susceptor must have excellent plasma resistance and high heat conductivity.
For such a susceptor, a susceptor formed from a ceramic sintered body having excellent plasma-resistance and thermal conductivity is used.
Heretofore, as an example of a susceptor formed from such a ceramic sintered body, a susceptor with a built-in plasma generation electrode as shown in
FIG. 7
is known.
This susceptor with a built-in plasma generation electrode
1
comprises: a mounting plate
2
, the upper surface of which serves as a mounting surface
2
a
on which a plate specimen such as a wafer or the like is mounted; a support plate
3
which is unified with this mounting plate
2
to support the mounting plate
2
; a plasma generation electrode
4
which is formed between the mounting plate
2
and the support plate
3
; and a power supply terminal
6
which is installed in a fixing hole
5
passing through the support plate
3
and makes contact with the plasma generation electrode
4
, and which also supplies external high frequency current to the plasma generation electrode
4
.
The above-described mounting plate
2
is flat and formed from an insulated ceramic sintered body, the support plate
3
is flat and formed from a insulated ceramic sintered body, and a susceptor substrate
7
is created by the mounting plate
2
and the support plate
3
.
Furthermore, the plasma generation electrode
4
comprises conductive layers whose main constituents are metals with high melting points such as tungsten (W), molybdenum (Mo), tantalum (Ta), niobium (Nb), and the like, and the value of whose resistance is uniform over these conductive layers.
The power supply terminal
6
is a rod whose main constituents are high melting point metals such as tungsten (W), molybdenum (Mo), tantalum (Ta), niobium (Nb) and the like.
In order to manufacture this susceptor with a built-in plasma generation electrode
1
, firstly the fixing hole
5
passing perpendicularly through the support plate
3
is formed at a predetermined location, and the power supply terminal
6
is fixed into this fixing hole
5
.
Next, this support plate
3
is coated with a conductive coating material
7
containing a high melting point metal powder so as to make contact with the power supply terminal
6
, and then dried. After this, the support plate
3
and the mounting plate
2
are superposed via the coated surface of this conductive coating material
7
and are unified by heat treatment under pressure, and also a plasma generation electrode
4
is formed between the support plate
3
and the mounting plate
2
by applying heat treatment to the conductive coating material
7
.
As above, a susceptor with a built-in plasma generation electrode
1
can be obtained in which the plasma generation electrode
4
and the power supply terminal
6
are joined reliably and firmly.
However, the susceptor
1
as described above has a problem in that, because the surface uniformity of a plate specimen of a wafer or the like is not always even after a process that uses plasma, such as deposition, etching and the like of the plate specimen, non-uniformity in the characteristics of the obtained semiconductor device is significant.
Especially as wafer diameters have increased in recent years, since non-uniformities of wafer surface characteristics must be minimized as much as possible, a susceptor, including a susceptor with a built-in plasma generation electrode that further enhances the uniformity of the surface after processing in a range of plasma processes has been much sought after.
Furthermore, cracking occurs easily in the vicinity of the connection of the plasma generation electrode
4
and the power supply terminal
6
, so that there is a problem in that durability of a susceptor with a built-in plasma generation electrode is not sufficient.
SUMMARY OF THE INVENTION
The present invention aims to solve the above-described problems with an object of providing a susceptor with a built-in plasma generation electrode that can make the throughput in a range of plasma processes on a mounted plate specimen more uniform, and which also has excellent plasma-resistance, thermal conductivity and durability, and a manufacturing method that allows a susceptor with a built-in plasma generation electrode to be produced easily and economically.
As a result of intensive research, the inventors discovered that in a conventional susceptor with a built-in plasma generation electrode, since the region in the vicinity of the connection of the plasma generation electrode and the power supply terminal becomes a high current density region during plasma generation, abnormal heat generation occurs easily in the vicinity of this connection, and consequently the throughput in a range of plasma processes on a mounted plate specimen becomes non-uniform. Moreover, they discovered that since cracking occurs easily in the vicinity of this connection, the durability of a susceptor with a built-in plasma generation electrode is not sufficient. Therefore, the inventors realized that if a part being a high current density region in a plasma generation electrode, that is the region in the vicinity of the connection of the plasma generation electrode and the power supply terminal, is made to be low resistance, then the above problem can be solved effectively, thereby arriving at the present invention.
In other words, a susceptor with a built-in plasma generation electrode of the present invention comprises: a susceptor substrate formed from a ceramic, one principal plane of which is a mounting surface on which a plate specimen is mounted; a plasma generation electrode built into this susceptor substrate; and a power supply terminal which is located so as to pass through the susceptor substrate and connected to the plasma generation electrode, wherein a region in the vicinity of the connection of the plasma generation electrode to the power supply terminal has a lower resistance than other regions of the plasma generation electrode.
In this susceptor with a built-in plasma generation electrode, since the region in the vicinity of the connection of the plasma generation electrode to the power supply terminal has a lower resistance than the other regions, abnormal heat generation is suppressed in the region (low resistance region) in the vicinity of the connection of the plasma generation electrode to the power supply terminal, so that the heat of the susceptor substrate is made uniform. This improves the heat uniformity of the mounting surface of the susceptor substrate, resulting in an improvement in heat uniformity of a plate specimen mounted onto the mounting surface, and the throughput by plasma processing of the plate specimen is made uniform. Furthermore, as a result of the improvement in heat uniformity of the mounting surface of the susceptor substrate, durability is improved significantly.
Preferably, the suscepto
Fuqua Shawntina
Ostrolenk Faber Gerb & Soffen, LLP
Sumitomo Osaka Cement Co. Ltd.
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