Electricity: electrical systems and devices – Electric charge generating or conducting means – Use of forces of electric charge or field
Reexamination Certificate
2001-04-03
2004-02-17
Leja, Ronald W. (Department: 2836)
Electricity: electrical systems and devices
Electric charge generating or conducting means
Use of forces of electric charge or field
C029S829000
Reexamination Certificate
active
06693789
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a susceptor and a manufacturing method thereof. More specifically, the present invention relates to a susceptor capable of reliably charging electricity to an inner electrode built in the susceptor, and a manufacturing method of the susceptor, which can manufacture the susceptor at high yield and at a low price.
2. Description of the Related Art
In a dry etching apparatus or a CVD apparatus used in the manufacturing process of semiconductors such as ICs, LSIs, or VLSIs, in order to evenly perform film formation by means of etching or CVD for each wafer, single wafer processing has been recently developed wherein a plate sample such as a semiconductor wafer, a liquid crystal substrate glass or a printed board is processed one by one. In this single wafer processing process, in order to hold the plate samples one at a time in a processing chamber, the plate sample is mounted on a sample stand (pedestal) referred to as a susceptor, and subjected to predetermined processing.
This susceptor must endure use in plasma, and also must endure use at high temperatures. Hence it is required to have excellent plasma resistance and large heat conductivity.
As such a susceptor, one consisting substantially of a ceramics sintered body with excellent plasma resistance and heat conductivity is used.
These susceptors include ones provided with an internal electrode such as an electrostatic chuck electrode for generating an electric charge thereinside for securing a plate sample with electrostatic attraction, a heater electrode for energizing with electricity and generating heat to heat the plate sample, or a plasma generating electrode for energizing with high-frequency power to generate plasma for plasma processing.
FIG. 3
shows one example of a susceptor having such an internal electrode built therein. The susceptor
15
comprises a placement plate
11
for placing a plate sample (not shown) thereon, a support plate
13
for supporting this placement plate
11
, an internal electrode
12
clamped and held between this placement plate
11
and the support plate
13
, and feeding terminals
14
inserted in the support plate
13
so as to come in contact with the internal electrode
12
, for supplying electric current to the internal electrode
12
.
As a manufacturing method of such susceptors
15
, there can be mentioned, for example, a method wherein fixation holes
16
for connecting the feeding terminals
14
to the internal electrode
12
are formed beforehand in the support plate
13
, feeding terminals
14
made of metal are mounted in these fixation holes
16
, an internal electrode
12
comprising a refractory metal such as tungsten, tantalum or molybdenum is arranged between the support plate having these feeding terminals
14
and the placement plate
11
, and these are bonded by various binders under application of pressure.
In the manufacturing method of such a susceptor
15
, however, at the time of bonding the placement plate
11
and the support plate
13
having the feeding terminals
14
, it is difficult to approximate the coefficient of thermal expansion of the placement plate
11
and the support plate
13
to that of the feeding terminals
14
. Also, it is necessary to use a refractory metal such as tungsten, tantalum or molybdenum, which has a high heat resistance and is expensive, for the metal forming the feeding terminals
14
.
Moreover, at the time of high-temperature bonding under application of pressure, since the Young's modulus of the feeding terminals
14
made of metal and the Young's modulus of the placement plate
11
and the support plate
13
are very different, if a large pressure is applied, these fracture due to a difference in the deformation modulus. Therefore, these cannot be pressed sufficiently, and the electrical connection between the feeding terminals
14
and the internal electrode
12
is thus not sufficient, or a gap occurs between the internal electrode
12
and the placement plate
11
. As a result, depending on the application of the internal electrode
12
, the electrostatic attractive force decreases, the heater heating performance decreases, or plasma is not generated on the placement plate
11
. Furthermore, the binder is exposed so that the constituents thereof volatilize and disperse, thereby contaminating the plate sample.
Therefore, in order to solve these problems, as a method of forming an internal electrode
12
in the susceptor
15
there is generally adopted a manufacturing method wherein, for example, a conductive paste in which an electrode material serving as the internal electrode
12
dispersed in an organic solvent or the like is printed on a support plate
13
in a predetermined pattern, and after the support plate
13
and a placement plate
11
are overlapped on each other and sintered and integrally formed via a surface on which the conductive paste comprising the electrode material is printed, fixation holes
16
are bored in the support plate
13
so as to reach the internal electrode
12
, in order to form a conductive circuit between the internal electrode
12
and the outside of the susceptor
15
, metallic feeding terminals
14
are mounted in these holes, and the metallic feeding terminals
14
and the internal electrode
12
are bonded via a brazing filler metal.
As another conventional built-in electrode type susceptor, there can be mentioned a susceptor comprising; a placement plate
11
for placing a plate sample thereon, a support plate
13
for supporting this placement plate
11
, a conductive binder layer serving as an internal electrode
12
and integrally bonding the placement plate
11
and the support plate
13
, and feeding terminals
14
buried in the support plate
13
so as to come in contact with the conductive binder layer, for feeding electric current to the internal electrode
12
. The placement plate
11
comprises a dielectric made of a nonconductive ceramics sintered body, the support plate
13
comprises a substrate made of a nonconductive ceramics sintered body, and the conductive bond layer is formed of organic matter or metal.
In this kind of built-in electrode type susceptor
15
, however, as described above, since the placement plate
11
and the support plate
13
are bonded by the conductive binder layer comprising a different material, bonding between the placement plate
11
and the support plate
13
is insufficient. Hence, corrosive gas or plasma enters in from the boundary therebetween, so that there is a possibility that the internal electrode
12
may be exposed to the gas or plasma, or that the bonding interface between the placement plate
11
and the support plate
13
may be broken, thereby causing a problem in that the corrosion resistance and the plasma resistance of the susceptor
15
is not sufficient.
In order to solve these problems, in the conventional manufacturing method of susceptors
15
, it is necessary to ensure the bonding between the placement plate
11
and the susceptor
13
, so that any gas or plasma does not enter into the junction.
As means for solving these problems, for example as shown in FIG.
4
and
FIG. 5
, there has been considered a method in which the above described placement plate
21
is structured with a ring-shape flange
21
a
provided on the side margin thereof to thereby form a disc-like concave portion
21
b,
and a support plate
23
having a conductive bond layer serving as an internal electrode
22
and a feeding terminal
24
built therein, is assembled into the concave portion
21
b
of the placement plate
21
. In this method, however, it is necessary to design the placement plate
21
in a shape having the above structure, and to design the conductive bond layer and the support plate
23
in a shape so as to fit into the concave portion
21
b
of the placement plate
21
without any gap. As a result, there is a problem in that the manufacturing process of the susceptor
25
becomes complicated.
As described above, in the manufactur
Inazumachi Hiroshi
Kawase Takeshi
Ootsuka Takeshi
Leja Ronald W.
Sumitomo Osaka Cement Co. Ltd.
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