Plasma processing apparatus and control method
Provided is a plasma processing apparatus including a microwave radiating mechanism configured to radiate microwaves output from a microwave output unit into a processing container. The microwave radiating mechanism includes: an antenna configured to radiate the microwaves; a dielectric member configured to transmit the microwaves radiated from the antenna, and form an electric field for generating surface wave plasma by the microwaves; a sensor provided in the microwave radiating mechanism or adjacent to the microwave radiating mechanism, and configured to monitor electron temperature of the generated plasma; and a controller configured to determine a plasma ignition state based on the electron temperature of the plasma monitored by the sensor.
1. A plasma processing apparatus comprising:
a microwave transmitter configured to radiate microwaves output from a microwave power source into a processing container, wherein the microwave transmitter includes:
an antenna configured to radiate the microwaves;
a microwave transmitting member formed of a dielectric material and facing the processing container configured to transmit the microwaves radiated from the antenna, and form an electric field for generating surface wave plasma by the microwaves;
a sensor provided in the microwave transmitter and configured to monitor electron temperature of the generated plasma; and
a controller configured to determine a plasma ignition state based on the electron temperature of the plasma monitored by the sensor,
wherein a tip of the sensor is embedded in the microwave transmitting member without being exposed to the processing container.
2. The plasma processing apparatus according to claim 1 , wherein N microwave transmitters are disposed in a circumferential direction of a ceiling plate of the processing container, wherein N≥2, M sensors are provided, wherein M equals to N or a multiple of N, and the controller determines the plasma ignition states corresponding to the N microwave transmitters based on the electron temperature of the plasma monitored by the M sensors.
3. The plasma processing apparatus according to claim 1 , wherein the sensor is coated with an insulating material.
4. The plasma processing apparatus according to claim 1 , wherein assuming that a height Z0 of an inner surface of a ceiling plate of the processing container is 0, an electron temperature of the plasma measured by the sensor at the height Z0 is Te0, a distance from the inner surface of the ceiling plate to a workpiece is Z, and pressure in the processing container is p, the controller corrects the electron temperature Te0 of the plasma measured by the sensor to an electron temperature Te(Z) of the plasma on the workpiece based on the following Equation 1, and controls a distribution of the plasma based on the corrected electron temperature Te(Z) of the plasma.
{
Te
(
z
)
=
Te
0
e
-
α
z
α
(
p
)
=
-
0.018
ln
(
p
[
Torr
]
)
+
0.1235
.
(
1
)
5. The plasma processing apparatus according to claim 4 , wherein assuming that a height ZO of an inner surface of a ceiling plate of the processing container is 0, electron density of the plasma measured by the sensor at the height ZO is NeO, a distance from the inner surface of the ceiling plate to a workpiece is Z, and pressure in the processing container is p, the controller corrects the electron density Ne0 of the plasma measured by the sensor to electron density Ne(Z) of the plasma on the workpiece based on the following Equation 2, and controls a distribution of the plasma based on the corrected electron density Ne(Z) of the plasma.
Ne
{
z
)
=
Ne
0
(
1
-
e
-
β
z
)
e
-
ϛ
z
β
(
p
)
=
0.0056
e
0.798
p
[
torr
]
ϛ
(
p
)
=
0.00891
n
(
p
[
Torr
]
)
+
0.0612
.
(
2
)
6. The plasma processing apparatus according to claim 5 , wherein the controller controls at least any one of power and a phase of the microwaves radiated to the microwave transmitter based on corrected electron temperature Te(Z) of the plasma and corrected electron density Ne(Z) of the plasma.
7. The plasma processing apparatus according to claim 1 , wherein assuming that a height Z0 of an inner surface of a ceiling plate of the processing container is 0, electron density of the plasma measured by the sensor at the height Z0 is Ne0, a distance from the inner surface of the ceiling plate to a workpiece is Z, and pressure in the processing container is p, the controller corrects the electron density Ne0 of the plasma measured by the sensor to electron density Ne(Z) of the plasma on the workpiece based on the following Equation 2, and controls a distribution of the plasma based on the corrected electron density Ne(Z) of the plasma
Ne
{
z
)
=
Ne
0
(
1
-
e
-
β
z
)
e
-
ϛ
z
β
(
p
)
=
0.0056
e
0.798
p
[
torr
]
ϛ
(
p
)
=
0.00891
n
(
p
[
Torr
]
)
+
0.0612
.
(
2
)
8. A control method of controlling plasma using a plasma processing apparatus including a microwave transmitter configured to radiate microwaves output from a microwave power source into a processing container,
wherein the microwave transmitter includes:
an antenna configured to radiate the microwaves;
a microwave transmitting member formed of a dielectric material and facing the processing container configured to transmit the microwaves radiated from the antenna, and form an electric field for generating surface wave plasma by the microwaves;
a sensor provided in the microwave transmitter and configured to monitor electron temperature of the generated plasma; and
a controller configured to determine a plasma ignition state based on the electron temperature of the plasma monitored by sensor, the control method comprising:
determining a plasma ignition state based on the electron temperature of the plasma monitored by the sensor,
wherein a tip of the sensor is embedded in the microwave transmitting member without being exposed to processing container.