Electric lamp and discharge devices: systems – Discharge device load with fluent material supply to the... – Plasma generating
Reexamination Certificate
2001-10-15
2003-03-25
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Discharge device load with fluent material supply to the...
Plasma generating
C315S111710
Reexamination Certificate
active
06538388
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to plasma processing apparatuses, plasma processing systems, and performance validation systems and performance inspection methods thereof. In particular, the present invention relates to a technology which is suitable for power supply of higher frequencies and achieves improvements in power consumption efficiency and coating layer characteristics.
2. Description of the Related Art
FIG. 32
illustrates a typical conventional dual-frequency excitation plasma processing apparatus which performs a plasma process such as a chemical vapor deposition (CVD) process, a sputtering process, a dry etching process, or an ashing process. This plasma processing apparatus is provided with a matching circuit
2
A which is disposed between a radiofrequency generator
1
and a plasma excitation electrode (cathode)
4
. The matching circuit
2
A matches the impedance between the radiofrequency generator
1
and the excitation electrode
4
.
Radiofrequency power from the radiofrequency generator
1
is fed to the plasma excitation electrode
4
via the matching circuit
2
A and a feed plate
3
. The matching circuit
2
A is accommodated in a matching box
2
which is a housing composed of a conductive material. The plasma excitation electrode
4
and the feed plate
3
are covered by a conductive chassis
21
.
The plasma excitation electrode
4
is provided with projections
4
a
at the bottom face thereof. A shower plate
5
having many holes
7
provided under the plasma excitation electrode
4
is in contact with the projection
4
a
. The plasma excitation electrode
4
and the shower plate
5
define a space
6
. A gas feeding tube
17
comprising a conductor is connected to the space
6
. The gas feeding tube
17
is provided with an insulator
17
a
at the middle thereof so as to insulate the plasma excitation electrode
4
and the gas source.
Gas from the gas feeding tube
17
is fed into a chamber space
60
composed of a chamber wall
10
, via the holes
7
in the shower plate
5
. An insulator
9
insulates the plasma excitation electrode
4
from the chamber wall
10
. The exhaust system is not depicted in the drawing.
A susceptor electrode (wafer susceptor)
8
which holds a substrate
16
and functions as another plasma excitation electrode is provided in the chamber space
60
. The wafer susceptor
8
is provided with a susceptor shield
12
thereunder.
The susceptor shield
12
comprises a shield supporting plate
12
A for sustaining the susceptor electrode
8
and a cylindrical support
12
B extending downward from the center of the shield supporting plate
12
A. The cylindrical support
12
B extends through a chamber bottom
10
A, and the lower portion of the cylindrical support
12
B and the chamber bottom
10
A are hermetically sealed with a bellows
11
.
The shaft
13
and the susceptor electrode
8
are electrically isolated from the susceptor shield
12
by a gap between the susceptor shield
12
and the susceptor electrode
8
and by insulators
12
C provided around the shaft
13
. The insulators
12
C also maintain high vacuum in the chamber space
60
. The susceptor electrode
8
and the susceptor shield
12
can be moved vertically by the bellows
11
to control the distance between the two electrodes
4
and
8
.
The susceptor electrode
8
is connected to a second radiofrequency generator
15
via the shaft
13
and a matching circuit accommodated in a matching box
14
. The chamber wall
10
and the susceptor shield
12
have the same DC potential.
FIG. 33
illustrates another example of conventional plasma processing apparatuses. Unlike the plasma processing apparatus shown in
FIG. 32
, the plasma processing apparatus shown in
FIG. 33
is of a single-frequency excitation type. In detail, a radiofrequency power is supplied only to a cathode
4
, a susceptor electrode
8
being grounded. Moreover, the matching box
14
and the radiofrequency generator
15
shown in
FIG. 32
are not provided. The susceptor electrode
8
and a chamber wall
10
have the same DC potential.
In these conventional plasma processing apparatuses, power with a frequency of approximately 13.56 MHz is generally supplied to generate a plasma between the electrodes
4
and
8
. A plasma process such as a plasma-enhanced CVD process, a sputtering process, a dry etching process, or an ashing process is then performed using the plasma.
The validation and evaluation of operation of the above-described plasma processing apparatuses have been performed by actual layer deposition and evaluation of the characteristics of the deposited layer, as follows.
Procedure (1): Deposition rate and planar uniformity
Step 1: Depositing a required layer on a 6-inch substrate by a plasma-enhanced CVD process.
Step 2: Patterning a resist layer by photolithography.
Step 3: Dry-etching the layer.
Step 4: Removing the resist layer by ashing.
Step 5: Measuring the surface roughness using a contact displacement meter to determine the layer thickness.
Step 6: Calculating the deposition rate from the deposition time and the layer thickness.
Step 7: Measuring the planar uniformity at 16 points on the substrate surface.
Procedure (2): BHF etching rate
A resist mask is patterned as in Steps 1 and 2 in Procedure (1).
Step 3: Immersing the substrate in a buffered hydrofluoric acid (BHF) solution for one minute to etch the layer.
Step 4: Rinsing the substrate with deionized water, drying the substrate, and removing the resist mask with a mixture of sulfuric acid and hydrogen peroxide (H
2
SO
4
+H
2
O
2
).
Step 5: Measuring the roughness as in Step 5 in Procedure (1) to determine the layer thickness after the etching.
Step 6: Calculating the etching rate from the immersion time and the reduced layer thickness.
Procedure (3): Isolation voltage
Step 1: Depositing a conductive layer on a glass substrate by a sputtering method and patterning the conductive layer to form a lower electrode.
Step 2: Depositing an insulating layer by a plasma-enhanced CVD process.
Step 3: Forming an upper electrode as in Step 1.
Step 4: Forming a contact hole for the lower electrode.
Step 5: Measuring the current-voltage characteristics (I-V characteristics) of the insulating layer by probing the upper and lower electrodes while varying the voltage up to approximately 200 V.
Step 6: Defining the isolation voltage as a voltage V at 100 pA corresponding 1 &mgr;A/cm
2
in a 100 &mgr;m square electrode.
The plasma processing apparatus has been required to achieve a higher plasma processing rate (a deposition rate or a processing rate), improved productivity, and improved planar uniformity in the plasma processing of substrates to be treated (a uniform distribution of the layer thickness and a uniform process in the planar direction). With an increased size of substrates in recent years, the requirement for planar uniformity is becoming more severe. Moreover, with an increased size of the substrate, the power required is also increased to the order of kilowatts, thus increasing the power consumption. As the capacity of the power supply increases, both costs for developing the power supply and for operating the apparatus consuming much power increase. Accordingly, it is desirable to reduce the operation costs.
Furthermore, an increase in power consumption leads to an increase in emission of carbon dioxide which places a burden on the environment. Since the power consumption is increased by the combination of an increase in the size of substrates and a low power consumption efficiency, there is a growing demand to reduce the carbon dioxide emission.
The plasma density generated in the plasma space can be improved by shifting the plasma excitation frequency to a higher side. For example, a frequency of 30 MHz or more in the VHF band can be used instead of the conventional 13.56 MHz. Thus, one possible way to improve the deposition rate in a deposition apparatus such as a plasma-enhanced CVD apparatus is to employ a higher plasma excitation frequency.
Another type of plasma pr
Nakano Akira
Ohmi Tadahiro
Alps Electric Co. ,Ltd.
Brinks Hofer Gilson & Lione
Dinh Trinh Vo
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