Data processing: generic control systems or specific application – Specific application – apparatus or process – Product assembly or manufacturing
Reexamination Certificate
2001-11-02
2004-03-30
Picard, Leo (Department: 2125)
Data processing: generic control systems or specific application
Specific application, apparatus or process
Product assembly or manufacturing
C700S108000, C702S183000, C438S010000
Reexamination Certificate
active
06714833
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a performance evaluation method, a maintenance method, a performance validation system, and a performance validation system for a plasma processing apparatus and relates to a plasma processing apparatus. In particular, the present invention relates to a technology for maintaining the performance of the plasma processing apparatus at a desired level.
2. Description of the Related Art
FIG. 40
illustrates a typical conventional dual-frequency excitation plasma processing unit which constitutes a plasma processing apparatus and performs a plasma process such as a chemical vapor deposition (CVD) process, a sputtering process, a dry etching process, or an ashing process.
In the plasma processing unit shown in
FIG. 40
, a matching circuit
2
A is connected between a radiofrequency generator
1
and a plasma excitation electrode
4
. The matching circuit
2
A matches the impedances of the radiofrequency generator
1
and the excitation electrode
4
.
Radiofrequency power generated in the radiofrequency generator
1
is supplied to the plasma excitation electrode
4
through 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 chassis
21
composed of a conductor.
An annular projection
4
a
is provided on the bottom face of the plasma excitation electrode (cathode)
4
, and a shower plate
5
having many holes
7
comes into contact with the projection
4
a
below the plasma excitation electrode
4
. 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
and 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 introduced inside a plasma processing chamber
60
surrounded by a chamber wall
10
, via the holes
7
in the shower plate
5
. An insulator
9
is disposed between the chamber wall
10
and the plasma excitation electrode (cathode)
4
for insulation therebetween. The exhaust system is omitted from the drawing.
A wafer susceptor (susceptor electrode)
8
which holds a substrate
16
and also functions as another plasma excitation electrode is installed inside the plasma processing chamber
60
. A susceptor shield
12
is disposed under the wafer susceptor
8
.
The susceptor shield
12
comprises a shield supporting plate
12
A for supporting 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 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 plasma processing chamber
60
. The susceptor electrode
8
and the susceptor shield
12
can be moved vertically by the bellows
11
so as to control the distance between plasma excitation electrodes
4
and the susceptor electrode
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. 41
illustrates another conventional plasma processing unit. This plasma processing unit is of a single-frequency excitation type. In other words, radiofrequency power is supplied only to the cathode electrode
4
, the susceptor electrode
8
being grounded. Thus, the matching box
14
and the radiofrequency generator
15
shown in
FIG. 40
are not provided. The susceptor electrode
8
and the chamber wall
10
have the same DC potential.
In these plasma processing units, power with a frequency of approximately 13.56 MHz is generally supplied to generate a plasma between the electrodes
4
and
8
which is used for a plasma process such as a plasma-enhanced CVD process, a sputtering process, a dry etching process, or an ashing process.
These plasma processing units each, however, does not always exhibit a high power consumption rate in the plasma space (the ratio of the electrical power consumed in the plasma space to the electrical power supplied from the radiofrequency generator
1
to the plasma excitation electrode
4
). In particular, the power consumption rate in the plasma space decreases noticeably as the frequency of the radiofrequency waves from the radiofrequency generator increases. Moreover, the power consumption rate decreases noticeably as the size of the substrate to be treated increases.
Such a decrease in power consumption rate results in a decreased layer deposition rate. When an insulating film is deposited, the resulting insulating film will not exhibit a high isolation voltage.
The operation validation and performance evaluation of the above-described plasma processing units have been performed by actual processing such as deposition and evaluation of characteristics of the resulting layers according to following Procedures:
Procedure (1) Deposition Rate and Planar Uniformity
Step 1: Depositing a desired layer on a 6-inch substrate by a plasma-enhanced CVD process.
Step 2: Patterning a resist layer.
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 (1) above.
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 separating the resist mask using a mixture of sulfuric acid and hydrogen peroxide (H
2
SO
4
+H
2
O
2
).
Step 5: Measuring the surface 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 method.
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 upper and lower electrodes by using probes while applying a voltage up to approximately 200 V.
Step 6: Defining the isolation voltage as the voltage V at 100 pA corresponding to 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), increased productivity, and improved planar uniformity of the plasma processing (planar uniformity of the layer thickness and the process variation). As the size of substrates has been increasing in recent years, the requirement of planar uniformity has become severer. Moreover, as the size of the substrate increases, the power required also increases to the order of kilowatts, thus increasing the power consumption. Accordingly, as the capacity of the power supply increases, both the cost for developing the power supply and the power consumption during the operation of the apparatus increase. In this respect, it is desirab
Nakano Akira
Ohmi Tadahiro
Alps Electric Co. ,Ltd.
Beyer Weaver & Thomas
Frank Elliot
Picard Leo
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