JP2004193149A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma processing apparatus which is capable of stabilizing the discharge without changing the process characteristics. <P>SOLUTION: The plasma processing apparatus is equipped with a vacuum charger 1 possessing a dielectric window 2 and housing a wafer W inside, a gas feed pipe 11 which feeds reaction gas into the vacuum charger 1, a high-frequency feed mechanism which is provided with a high-frequency power supply unit 5 to feed high-frequency waves from the high-frequency power supply unit 5 into the vacuum charger 1 through the dielectric window 2 to turn the reaction gas into a plasma for processing the wafer W, an electrode 8 provided inside the vacuum charger 1, and a DC power supply 9 applying an optional DC voltage to the electrode 8. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing apparatus and a processing method used for manufacturing a thin film element such as a semiconductor element or a liquid crystal display, or as a particle beam source or an analyzer.
[0002]
[Prior art]
This type of plasma processing apparatus includes a reaction chamber, and a vacuum chamber made of a metal having a ground potential is used as the reaction chamber. The inner wall of the vacuum chamber is often coated with an insulating material.
[0003]
When the inner wall of the vacuum chamber is coated with an insulator, the generated plasma is in a state of being insulated from a ground potential in terms of direct current. Therefore, the DC potential of the plasma does not have a reference potential, and can be an arbitrary potential (for example, see Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-306891
[Problems to be solved by the invention]
However, when the DC potential of the plasma does not have a reference potential, the plasma potential changes depending on process conditions and differences between apparatuses, and also changes over time, which is one factor that causes a change in process characteristics. Become.
[0006]
In addition, when the insulating coating on the inner wall of the vacuum chamber is partially removed by the plasma etching action and the metal at the earth potential is exposed, if the difference between the plasma potential and the earth potential is large, the discharge state is not good. There is also the problem of becoming stable.
[0007]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plasma processing apparatus capable of stabilizing a discharge state without changing process characteristics. And
[0008]
[Means for Solving the Problems]
In order to solve the above-described problem, the first aspect of the present invention includes a vacuum container for accommodating a substrate to be processed therein, gas supply means for supplying a reaction gas into the vacuum container, and a high-frequency power supply unit. A high-frequency supply unit for supplying the high-frequency power from the high-frequency power supply unit into the vacuum chamber through a dielectric window, an antenna, an electrode, or the like, thereby converting the reaction gas into plasma and processing the substrate to be processed, An electrode provided in the vacuum vessel and voltage applying means for applying an arbitrary DC voltage to the electrode are provided.
[0009]
According to a fifth aspect of the present invention, there is provided a vacuum container accommodating a substrate to be processed therein, gas supply means for supplying a reaction gas into the vacuum container, and a high-frequency power supply unit. A high-frequency supply unit for processing the substrate to be processed by turning the reaction gas into plasma by supplying the inside of the vacuum container through a dielectric window, an antenna, an electrode, and the like, and an electrode provided in the vacuum container. Voltage applying means for applying an arbitrary DC voltage to the electrode, potential measuring means for measuring the potential of the electrode, and switching means for selectively connecting the potential measuring means and the voltage applying means to the electrode. Is provided.
[0010]
According to a sixth aspect of the present invention, there is provided a vacuum container accommodating a substrate to be processed therein, gas supply means for supplying a reaction gas into the vacuum container, and a high-frequency power supply unit. A high-frequency supply unit configured to supply the reaction gas into plasma to process the substrate by supplying the reaction gas into the plasma through a dielectric window, an antenna, an electrode, and the like; And a second electrode, voltage applying means for applying an arbitrary DC voltage to the first electrode, and potential measuring means for measuring the potential of the second electrode.
[0011]
According to a seventh aspect of the present invention, there is provided a vacuum container having a dielectric window and accommodating a substrate to be processed therein, gas supply means for supplying a reaction gas into the vacuum container, and a high-frequency power supply unit. A high-frequency power supply unit configured to supply the high-frequency power from the high-frequency power supply unit to the inside of the vacuum chamber through a dielectric window, an antenna, an electrode, or the like, to convert the reaction gas into plasma and process the substrate to be processed; An electrode provided therein, a potential measuring means for measuring the potential of the electrode, and stopping the supply of high frequency by the high frequency supply means based on the potential measuring means measuring a potential equal to or higher than a predetermined value, or Control means for generating an alarm.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
[0013]
FIG. 1 is a schematic configuration diagram showing a plasma processing apparatus according to one embodiment of the present invention.
[0014]
In FIG. 1, reference numeral 1 denotes a vacuum chamber (vacuum vessel) made of aluminum coated with alumite (dielectric material), and the inner wall surface of the vacuum chamber (vacuum vessel) is coated with an insulating material. A quartz plate 2 constituting a dielectric window is provided on the ceiling of the vacuum chamber 1, and a coil 3 for plasma generation is provided on an upper surface of the quartz plate 2. A high frequency power supply 5 as high frequency supply means is connected to the plasma generating coil 3. A high frequency power of, for example, 13.56 MHz is applied to the plasma generating coil 3 to generate plasma.
[0015]
A lower electrode 6 also serving as a mounting portion is provided on the inner bottom of the vacuum chamber 1, and a wafer W as a substrate to be processed is mounted on the lower electrode 6. A high-frequency power source 7 is connected to the lower electrode 6, and a high-frequency power is also applied to the lower electrode 6. A gas supply pipe 11 as a gas supply means for supplying a reaction gas and a gas exhaust pipe 12 for evacuation are connected to one side wall of the vacuum chamber 1.
[0016]
In the vicinity of the inner wall surface on one side of the vacuum chamber 1, for example, an electrode 8 made of a conductor or a semiconductor and made of aluminum is provided. A DC power supply 9 is connected to the electrode 8 so that a DC voltage can be applied.
[0017]
Next, a case where the wafer W is subjected to the etching process will be described.
[0018]
First, a gate valve (not shown) is opened, and the wafer W is mounted on the lower electrode 6 by a transfer arm (not shown). After this mounting, the gate valve is closed and the inside of the vacuum chamber 1 is evacuated to evacuate to a predetermined degree of vacuum. Thereafter, an etching gas is supplied from the gas supply pipe 11 into the vacuum chamber 1.
[0019]
Then, a high frequency power of, for example, 13.56 MHz is applied to the coil 3 from the high frequency power supply 5, and a high frequency power of, for example, 13.56 MHz is applied to the lower electrode 6 from the high frequency power supply 7.
[0020]
As a result, high frequency is supplied from the coil 3 into the vacuum vessel 1 via the quartz plate 2, and the high frequency turns the etching gas into plasma, thereby etching the surface of the wafer W.
[0021]
FIG. 2 shows that when a discharge is performed using a mixed gas of CF ₄ and O ₂ as a reaction gas and the electrode 8 is not arranged in the vacuum chamber 1, the electrode 8 is arranged in the vacuum chamber 1 and the potential of the electrode 8 is changed. FIG. 7 is a graph showing the results of measurement of the plasma floating potential in the vacuum chamber 1 in the case where is set to 0 V and the potential of the electrode 8 is changed to −18 V.
[0022]
From this graph, it can be seen that the plasma floating potential decreases in the order where the electrode 8 is not provided, the potential of the electrode 8 is 0 V, and the potential of the electrode 8 is −18 V.
[0023]
By the way, the plasma potential is considered to be about 20 V higher than the plasma floating potential when the electrode 8 is not provided, when the potential of the electrode 8 is 0 V, and when the potential of the electrode 8 is −18 V. This indicates that the control can be performed by the voltage applied to the electrode 8.
[0024]
As described above, by disposing the electrode 8 in the vacuum charger 1 and applying a DC voltage to the electrode 8, a DC voltage that is a reference for the plasma potential can be applied. Therefore, it is possible to prevent the plasma potential from fluctuating due to uncertain factors such as a difference between apparatuses and a change with time.
[0025]
The plasma potential can be controlled by changing the voltage applied to the electrode 8. Therefore, even when the insulating coating on the inner wall of the vacuum chamber 1 is partially removed and the metal at the ground potential is exposed, it is possible to control the potential difference between the plasma potential and the ground potential to stabilize the discharge.
[0026]
FIG. 3 is a schematic configuration diagram showing a plasma processing apparatus according to a second embodiment of the present invention.
[0027]
The same portions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
[0028]
In the second embodiment, a voltmeter 15 as a voltage measuring means and a changeover switch 16 as a changeover means are provided, and the DC power supply 9 and the voltmeter 15 are selectively connected to the electrode 8 by the changeover operation of the changeover switch 16. I can do it.
[0029]
According to the second embodiment, the change in the plasma floating potential can be monitored by the voltmeter 15. For example, when the plasma floating potential changes due to an abnormality of the apparatus or a change with time, the changeover switch 15 is operated. The plasma potential can be controlled by applying a DC voltage to the electrode 8.
[0030]
FIG. 4 shows a plasma processing apparatus according to a third other embodiment of the present invention.
[0031]
The same portions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
[0032]
In the third embodiment, first and second electrodes 21 and 22 are provided in a vacuum chamber 1, and a DC power supply 23 as a voltage applying means, a second electrode A voltmeter 24 is connected to 22 as potential measuring means.
[0033]
In the third embodiment, when the measured value of the plasma floating potential by the voltmeter 24 is greatly increased based on the application of the DC voltage to the first electrode 21 by the DC power supply 23, It is determined that the coating of the insulator on the wall surface is not peeled off, and when the measured value of the plasma floating potential by the voltmeter 24 does not increase so much, it is determined that the coating of the insulator is peeled off.
[0034]
According to the third embodiment, the same operation and effect as those of the first embodiment can be obtained.
[0035]
FIG. 5 is a schematic configuration diagram illustrating a plasma processing apparatus according to a fourth embodiment of the present invention.
[0036]
The same portions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
[0037]
In the fourth embodiment, a rectifying plate 31 for rectifying the reaction gas is provided in the vacuum chamber 1 so as to surround the lower electrode 6, and the rectifying plate 31 is also used as an electrode. A DC power supply 32 is connected so that a DC voltage is applied.
[0038]
According to the fourth embodiment, the same operation and effect as those of the above-described first embodiment can be obtained.
[0039]
Further, in the fourth embodiment, since the current plate 31 is also used as an electrode, the number of components can be reduced, and the cost can be reduced.
[0040]
FIG. 6 shows a plasma processing apparatus according to a fifth other embodiment of the present invention.
[0041]
The same portions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
[0042]
In the fifth embodiment, an electrode 35 for measuring a potential is provided inside the vacuum chamber 1, and a voltmeter 36 as a voltage applying means is connected to the electrode 35.
[0043]
A dielectric window 38 is provided on the ceiling of the vacuum chamber 1, and the size of the dielectric window 38 is increased, and the dielectric window 38 includes a plurality of windows 38a. These windows 38a are constituted by an alumina plate 39 and a quartz plate 40. The plurality of alumina plates 39 are supported by aluminum / alumite beams 41, and the quartz plate 40 is fixed to the beams 41 by screws. A gap is formed between the quartz plates 40, and the beam 41 is exposed from the gap.
[0044]
The coil 3 for generating inductively coupled plasma is provided on the upper surface of the alumina plate 39 so that plasma is generated.
[0045]
FIG. 7 shows the result of monitoring the plasma floating potential in FIG. 6 with a pen recorder.
[0046]
By continuing the discharge, the alumite of the aluminum / alumite beam 41 is etched by the plasma, and when the aluminum is exposed, the plasma floating potential rises from -8.5V (normal potential) to 27V. .
[0047]
When the plasma potential started to rise in this way, it was visually confirmed that an arc discharge was generated in the portion of the aluminum / alumite beam 41.
[0048]
As described above, the control means 45 stops the generation of the plasma or issues an alarm based on the fact that the voltmeter 36 measures the potential equal to or higher than the predetermined value.
[0049]
Further, the threshold value of the potential rise for stopping the generation of the plasma or issuing an alarm is 5 V or more.
[0050]
According to the fifth embodiment, it is possible to avoid an arc discharge in the beam 41 in advance.
[0051]
The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the invention.
[0052]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a plasma processing apparatus that controls a plasma potential to stabilize process characteristics and a discharge state.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing a plasma processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a graph showing a change in plasma floating potential in the plasma processing apparatus of FIG.
FIG. 3 is a configuration diagram schematically showing a plasma processing apparatus according to a second embodiment of the present invention.
FIG. 4 is a configuration diagram schematically showing a plasma processing apparatus according to a third embodiment of the present invention.
FIG. 5 is a configuration diagram schematically showing a plasma processing apparatus according to a fourth embodiment of the present invention.
FIG. 6 is a configuration diagram schematically showing a plasma processing apparatus according to a fifth embodiment of the present invention.
FIG. 7 is a graph showing a change in plasma floating potential in the plasma processing apparatus of FIG.
[Explanation of symbols]
W: Wafer (substrate to be processed), 1: vacuum chamber (vacuum vessel), 3: coil, 5: high frequency power supply (high frequency supply means), 8: electrode, 9: DC power supply (voltage application means), 11: gas supply Tube (gas supply means), 15: potential measurement means, 16: changeover switch (switching means), 21: first electrode, 22: second electrode, 23: DC power supply (voltage application means), 24: voltmeter (Potential measuring means), 31 ... rectifier plate, 35 ... battery, 36 ... potential measuring means, 38 ... dielectric window, 38a ... window part, 41 ... beam.

Claims (9)

A vacuum container for storing the substrate to be processed therein;
Gas supply means for supplying a reaction gas into the vacuum vessel;
A high-frequency power supply unit that has a high-frequency power supply unit and supplies high-frequency power from the high-frequency power supply unit to the inside of the vacuum vessel to convert the reaction gas into plasma and process the substrate to be processed;
An electrode provided in the vacuum vessel,
Voltage applying means for applying an arbitrary DC voltage to the electrode;
A plasma processing apparatus comprising: The plasma processing apparatus according to claim 1, wherein the vacuum vessel is made of a dielectric or a metal coated with a dielectric. 2. The plasma processing apparatus according to claim 1, wherein the surface of the electrode is made of a conductor or a semiconductor. The plasma processing apparatus according to claim 1, wherein the electrode is also used as a rectifying plate for controlling the flow of the reaction gas. A vacuum container for storing the substrate to be processed therein;
Gas supply means for supplying a reaction gas into the vacuum vessel;
A high-frequency power supply unit that has a high-frequency power supply unit and supplies high-frequency power from the high-frequency power supply unit to the inside of the vacuum vessel to convert the reaction gas into plasma and process the substrate to be processed;
An electrode provided in the vacuum vessel,
Voltage applying means for applying an arbitrary DC voltage to the electrode;
Potential measuring means for measuring the potential of the electrode,
Switching means for selectively connecting the potential measuring means and the voltage applying means to the electrode,
A plasma processing apparatus comprising: A vacuum container for storing the substrate to be processed therein;
Gas supply means for supplying a reaction gas into the vacuum vessel;
A high-frequency power supply unit that has a high-frequency power supply unit and supplies high-frequency power from the high-frequency power supply unit to the inside of the vacuum vessel to convert the reaction gas into plasma and process the substrate to be processed;
First and second electrodes provided in the vacuum vessel;
Voltage applying means for applying an arbitrary DC voltage to the first electrode;
Potential measuring means for measuring the potential of the second electrode;
A plasma processing apparatus comprising: A vacuum container having a dielectric window and accommodating the substrate to be processed therein,
Gas supply means for supplying a reaction gas into the vacuum vessel;
A high-frequency power supply unit that has a high-frequency power supply unit, and supplies high-frequency waves from the high-frequency power supply unit into the vacuum chamber through the dielectric window to convert the reaction gas into plasma and process the substrate to be processed; ,
An electrode provided in the vacuum vessel,
Potential measuring means for measuring the potential of the electrode;
A plasma processing apparatus comprising: control means for stopping supply of high frequency by the high frequency supply means or generating an alarm based on the potential measurement means measuring a potential equal to or higher than a predetermined value. The dielectric window is constituted by a plurality of windows supported by beams coated with an insulator,
A gap is formed between the plurality of windows,
The plasma processing apparatus according to claim 7, wherein the beam is exposed to the inside of the vacuum chamber through the gap. 8. The plasma processing apparatus according to claim 7, wherein a threshold value of a potential increase at which the supply of the high frequency by the high frequency supply unit is stopped or a warning is issued is 5 V or more.

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