Plasma processing method and plasma processing apparatus
View Patent ↗The invention provides a plasma processing apparatus and a dry etching method for etching a multilayered film structure having steps with high accuracy. The plasma processing apparatus comprises a vacuum reactor 107 , a lower electrode 113 placed within a processing chamber of the vacuum reactor and having a wafer 112 to be etched mounted on the upper surface thereof, bias supplying units 118 and 120 for supplying high frequency power for forming a bias potential to the lower electrode 113 , a gas supply means 111 for feeding reactive gas into the processing chamber, an electric field supplying means 101 through 103 for supplying a magnetic field for generating plasma in the processing chamber, and a control unit 127 for controlling the distribution of ion energy in the plasma being incident on the wafer 112 via the high frequency power.
1. A plasma processing apparatus comprising a vacuum reactor, a lower electrode placed in a processing chamber of the vacuum reactor and capable of having placed thereon a wafer, a bias supplying mechanism for supplying a bias power of a plurality of different frequencies to the lower electrode, a gas supply mechanism for introducing a reactive gas into the processing chamber, a pressure control mechanism for controlling a pressure in the processing chamber, an electromagnetic wave supplying mechanism for supplying electromagnetic wave for generating plasma in the processing chamber, and a control device which respectively controls the bias supplying mechanism, the gas supply mechanism, the pressure control mechanism, and the electromagnetic wave supplying mechanism, wherein
the bias supplying mechanism comprises
an ion energy distribution control mechanism for controlling a distribution of energy of ions being incident on the wafer, and
a plasma status detector configured to detect a time variation of an impedance of the plasma when a high-frequency bias power of a plurality of different frequencies are supplied to the wafer, and isolate the detected time variation of impedance of the plasma into an impedance of a component of a wall surface status of the processing chamber and an impedance of a component above the wafer, and
the control device is configured to determine an end point of plasma processing of the wafer based on a time variation of either the isolated the impedance of the component above the wafer or the isolated impedance of the component of the wall surface status of the processing chamber.
2. The plasma processing apparatus according to claim 1 , wherein
the bias supplying mechanism comprises a power supply unit for oscillating a plurality of frequencies, a matching box corresponding to the plurality of frequencies, and an impedance detector with respect to the plurality of different frequencies, or comprises a power supply unit for oscillating a plurality of different frequencies, a matching box corresponding to the plurality of frequencies, and a mechanism for detecting a current, a voltage and a phase with respect to the plurality of different frequencies.
3. The plasma processing apparatus according to claim 1 , wherein
the plasma state detector isolates the detected time variation of impedance of the plasma into the impedance of the component of the wall surface status of the processing chamber and the impedance of the component above the wafer, using equation (1) in which the voltage, the current, the impedance of the component above the wafer, and the impedance of the wall state component of the processing chamber at the time when the high frequency bias power of high frequency is supplied are respectively represented by V H , I H , Z 1H , and Z 2H , equation (2) in which the voltage, the current, the impedance of the component above the wafer, and the impedance of the wall state component of the processing chamber at the time when the high frequency bias power of low frequency is supplied are respectively represented by V L , I L , Z 1L , and Z 2L , and equation (3) in which an angular speed of the high frequency bias of high frequency and an angular speed of the high frequency bias of low frequency are represented by ω H and ω L , the impedance of the component above the wafer at the time when the high frequency bias power of high frequency is supplied, the impedance of the component above the wafer at the time when the high frequency bias power of low frequency is supplied, a resistance component, a reactance component, an inductance component and a capacity component of the component above the wafer are respectively represented by Z 1H , Z 1L , R 1 , X 1 , L 1 , and C 1 , and the impedance of the wall state component of the processing chamber at the time when the high frequency bias power of high frequency is supplied, the impedance of the wall surface component of the processing chamber at the time when the high frequency bias power of low frequency is supplied, a resistance component, a reactance component, an inductance component, and a capacity component of the wall state component of the processing chamber are respectively represented by Z 2H , Z 2L , R 2 , X 2 , L 2 , and C 2
[
Equation
1
]
{
Z
1
H
I
H
+
Z
2
H
I
H
=
V
H
(
1
)
Z
1
L
I
L
+
Z
2
L
I
2
=
V
L
(
2
)
[
Equation
2
]
Z
x
y
=
R
x
+
j
(
ω
y
L
x
-
1
C
x
ω
y
)
(
3
)
=
R
x
+
j
X
x
y
x
=
1
,
2
;
y
=
H
or
L
.
4. The plasma processing apparatus according to claim 1 , wherein
the electromagnetic wave supplying mechanism comprises a power supply unit for supplying power for the electromagnetic wave, and a matching unit for storing a plurality of matching points with respect to the power supply unit and for selecting a matching path so as to perform matching.