JP3208079B2 - High frequency power application device and plasma processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing technique for performing fine processing by dry etching, thin film formation, surface modification, etc., utilizing plasma, a plasma generation technique used in the plasma processing, and a plasma processing method. The present invention relates to a high-frequency power application technique for generating power.

[0002]

2. Description of the Related Art In recent years, plasma processing has been widely used for surface processing of substances such as fine processing by dry etching, thin film formation and surface modification, and particularly in the field of semiconductors, ultra-high integrated circuit devices have been manufactured. It is an indispensable technology in doing so.

Conventionally, a capacitively-coupled parallel plate plasma generator has been widely used for plasma processing. this is,
While uniform plasma processing is required, uniform low-density plasma can be easily generated under relatively low vacuum pressure. However, as miniaturization of semiconductor integrated circuits has progressed, it has recently become necessary to generate high-density plasma under a high degree of vacuum. An inductively coupled plasma generator for generating plasma by acting on a plasma and a plasma processing apparatus using the same have attracted attention.

Hereinafter, an example of a conventional inductively coupled plasma processing apparatus will be described with reference to the drawings.

FIG. 18 is a schematic view of an inductively coupled plasma processing apparatus according to a first conventional example. In FIG. 18, reference numeral 101 denotes a cylindrical chamber, and the inside of the chamber 101 has a predetermined pressure. Is held. The chamber 101 is provided with a gas introduction unit, an exhaust unit, and a loading / unloading unit for loading / unloading an object to be processed, which are not shown.

An insulator 10 is provided at the bottom of the chamber 101.
2, a lower electrode (sample stage) 103 is provided, and the lower electrode 103 holds an object to be processed 104 such as a semiconductor wafer on which etching or film deposition is performed.

Above the chamber 101, a first radio frequency (RF) power supply 105 is provided, and a single spiral coil 106 having one end grounded is provided. First high frequency power supply 10
5 is connected to the other end of the spiral coil 106 via an impedance matching device 107. Also, chamber 1
A second high frequency power supply 108 is provided below 01. The second high-frequency power supply 108 is electrically insulated from the chamber 101 and the insulator 102, and is electrically connected to the lower electrode 103.
A high-frequency bias voltage is applied to the plasma generated in 1. For safety, the first high frequency power supply 1 is usually
05, the second high-frequency power supply 108 and the spiral coil 10
The ground potential of 6 is the same as that of the chamber 101.

Hereinafter, a method of performing plasma processing using the inductively coupled plasma processing apparatus according to the first conventional example will be described.

First, the workpiece 104 is loaded into the chamber 101 by a loading / unloading means (not shown), and the lower electrode 103 is loaded.
Hold on. Thereafter, the inside of the chamber 101 is maintained at a predetermined pressure by introducing a gas into the chamber 101 from a gas introduction unit (not shown) and exhausting the gas in the chamber 101 by an exhaust unit (not shown).

Next, high-frequency power is applied from the first high-frequency power supply 105 to the spiral coil 106, and high-frequency power is applied from the second high-frequency power supply 108 to the lower electrode 103. A high-frequency current flows through the spiral coil 106 by high-frequency power applied to the spiral coil 106, and an alternating magnetic field generated by the high-frequency current generates a chamber 101.
The electrons existing in the space inside the chamber 101 move in a direction to generate a magnetic field that cancels the magnetic field generated by the spiral coil 106.
When the electrons move by the inductive coupling, the gas in the chamber 101 is turned into plasma. In this case, since the impedance matching unit 107 performs impedance matching with the plasma, stable plasma discharge can be generated.

By causing the plasma generated in the chamber 101 to act on the object 104, the object 1 is processed.
This makes it possible to perform surface modification such as surface oxidation, surface nitridation, and impurity doping, and thin film formation and isotropic dry etching on the surface of the workpiece 104.

When Vpp (Peak-to-Peak voltage) and Vdc (DC potential of the lower electrode 103) generated by an AC bias voltage applied to the lower electrode 103 by the second high-frequency power supply 108 are used, Since the object 104 can be efficiently irradiated with ions, fine processing by anisotropic dry etching can be realized.

At the time when the processing of the object 104 is completed, the first high-frequency power supply 105 and the second high-frequency power supply 1
After the supply of the high-frequency power from the chamber 08 ends, the introduction of gas into the chamber 101 ends and the chamber 10
When the residual gas in 1 is exhausted and then the object 104 is taken out of the chamber 101, the plasma processing is completed.

FIG. 19 is a schematic view of an inductively coupled plasma processing apparatus according to a second conventional example. In FIG. 19, the same members as those of the inductively coupled plasma processing apparatus according to the first conventional example shown in FIG. In the second conventional example, a spiral coil 109 is provided on the side of the chamber 101 in place of the spiral coil 106 in the first conventional example. The method of performing plasma processing using the inductively coupled plasma processing apparatus according to the second conventional example is the same as that of the first conventional example.

FIG. 20 is a schematic view of an inductively coupled plasma processing apparatus according to a third conventional example. 20, the same members as those of the inductively coupled plasma processing apparatus according to the first conventional example shown in FIG. 18 are denoted by the same reference numerals, and description thereof is omitted. In the third conventional example, one spiral coil 106 in the first conventional example is used.
Instead, a multi-spiral coil 110 in which four coils are connected in parallel is provided. The method of performing plasma processing using the inductively coupled plasma processing apparatus according to the third conventional example is the same as that of the first conventional example.

[0016]

By the way, in the first and second prior arts, high frequency power having a frequency higher than 13.56 MHz is supplied to the spiral coil 106 or the spiral coil 109 to control the electron temperature of the plasma. , The reactance (jωL: j is an imaginary unit, ω is the angular frequency of the high frequency power, and L is the inductance of the coil) of the spiral coil 106 and the spiral coil 109 increases, making it difficult to achieve impedance matching. Become. Therefore, there is a problem that plasma discharge hardly occurs.

In the first and second conventional examples,
In order to generate a highly uniform plasma over a large area, the spiral coil 106 and the spiral coil 1
Since it is necessary to increase the length of 09 and the diameter thereof, it is inevitable that the inductance and thus the reactance further increase.

The third conventional example is proposed to solve the above-mentioned problem. The impedance is reduced by providing a multi-spiral coil 110 instead of the spiral coil 106 in the first conventional example. Things. Since it is easy to achieve impedance matching, plasma discharge is likely to occur.

However, in the inductively coupled plasma processing apparatus according to the third conventional example, a high frequency V of about 30 to 300 MHz is used to control the electron temperature of the plasma.
When using high frequency power in the HF band, about 20 mTorr
It has been difficult to generate plasma under a pressure lower than r, that is, under a high degree of vacuum.

As described above, in the conventional inductively coupled plasma processing apparatus, when high-frequency high-frequency power is applied to control the electron temperature of plasma, high-density plasma is generated under high vacuum pressure. Therefore, there is a problem that highly uniform and low-damage plasma processing cannot be performed with high accuracy.

In view of the above, it is a first object of the present invention to provide a high-frequency power applying device capable of efficiently supplying high-frequency high-frequency power.

It is a second object of the present invention to provide a plasma generating apparatus and a plasma generating method capable of generating plasma under a high vacuum pressure even when a high frequency high frequency power is applied.

It is a third object of the present invention to provide a plasma processing apparatus and a plasma processing method capable of performing highly uniform and low-damage plasma processing with high accuracy.

[0024]

According to the present invention, when the length of the coil is set to substantially an integral multiple of 1/4 of the wavelength of the high-frequency power applied to the coil, initial discharge is likely to occur.
It has been found based on the finding that plasma is easily generated.

The high-frequency power applying apparatus according to the present invention has a high-frequency power generating source for generating high-frequency power, and has a length substantially equal to １ ／ of the wavelength of the high-frequency power generated from the high-frequency power generating source, A coil that generates a magnetic field when a high-frequency power is supplied from the high-frequency power source and a high-frequency current flows, and an impedance matching device that performs impedance matching between the high-frequency power generation source and the coil.

According to the high-frequency power applying apparatus according to the present invention, since the coil has a length almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source, a standing wave is generated in the coil. The peak value of the voltage generated in the coil is increased because of the ease.

[0027] In the high-frequency power application device according to the present invention, the length of the coil may be 1/1 / the wavelength of the high-frequency power.
It is preferably within a range of ± 7% with respect to an integral multiple of 4.

Further, it is more preferable that the length of the coil is approximately ４ or １ ／ of the wavelength of the high frequency power.

Further, it is more preferable that the length of the coil is within a range of ± 7% with respect to ４ or 波長 of the wavelength of the high frequency power.

The frequency of the high frequency power is 30 MHz.
Preferably, it is z to 300 MHz.

Further, it is preferable that the impedance matching device is constituted by at least two variable capacitors.

Further, the coil has a length of substantially an integral multiple of 1/4 of the wavelength of the high-frequency power, and is constituted by a plurality of coil portions arranged point-symmetrically with respect to the coil center. Is preferred.

In this case, it is more preferable that each of the plurality of coil portions has an arc portion located on the same circumference.

Preferably, the coil is formed in a planar spiral shape. In this case, the planar spiral shape means a shape that continuously extends so that the diameter gradually increases toward the outside on one plane.

Further, it is preferable that the coil is formed in a three-dimensional spiral or spiral shape. in this case,
A three-dimensional spiral shape means a shape that continuously extends in a direction perpendicular to the diameter while the diameter gradually increases toward the outside, and a three-dimensional spiral shape while maintaining the same diameter A shape extending continuously in a direction perpendicular to the diameter is meant. The plasma generator according to the present invention comprises: a chamber whose inside is kept in a vacuum state; gas introduction means for introducing gas into the chamber; a high-frequency power generation source for generating high-frequency power; and the high-frequency power generation source. Has a length that is approximately an integral multiple of 1/4 of the wavelength of the generated high frequency power, and when high frequency power is supplied from the high frequency power source and a high frequency current flows, the gas introduced into the chamber is turned into plasma. A coil for generating a changing magnetic field;
An impedance matching device for matching the impedance between the high-frequency power generation source and the coil is provided.

According to the plasma generator according to the present invention,
Since the coil has a length that is almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source, the peak value of the voltage generated in the coil increases as described above.

The plasma processing apparatus according to the present invention has a chamber in which the inside is kept in a vacuum state, a sample table provided in the chamber for holding an object to be processed, and a gas introduced into the chamber. A gas introduction means, a high-frequency power generation source for generating high-frequency power, and a length substantially equal to 1/4 of the wavelength of the high-frequency power generated by the high-frequency power generation source; Is supplied and a high-frequency current flows, a coil that generates a magnetic field that turns the gas introduced into the chamber into a plasma, and an impedance matching device that matches the impedance between the high-frequency power generation source and the coil. I have.

According to the plasma processing apparatus of the present invention,
Since the coil has a length that is almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source, the peak value of the voltage generated in the coil increases as described above.

In the plasma processing apparatus according to the present invention,
It is preferable that the apparatus further includes a voltage application unit that applies at least one of a high-frequency voltage and a constant voltage that is electrically insulated from the chamber to the sample stage.

In this case, a first pulse modulator for pulse-modulating the high-frequency power generated from the high-frequency power generation source and a second pulse modulator for pulse-modulating the voltage applied by the voltage applying means are further provided. More preferably, it is provided.

According to the high frequency power applying method of the present invention, the high frequency power generated by the high frequency power generating source is supplied to a coil having a length substantially an integral multiple of 1/4 of the wavelength of the high frequency power generating source. And a step of generating a magnetic field in the coil by a high-frequency current flowing through the coil.

According to the high-frequency power application method according to the present invention, since the coil has a length almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source, a standing wave is generated in the coil. The peak value of the voltage generated in the coil is increased because of the ease.

In the high-frequency power applying method according to the present invention, the length of the coil is set to 1 / the wavelength of the high-frequency power.
It is preferably within a range of ± 7% with respect to an integral multiple of 4.

It is more preferable that the length of the coil is approximately ４ or １ ／ of the wavelength of the high frequency power.

The length of the coil is more preferably within a range of ± 7% with respect to １ ／ or 波長 of the wavelength of the high frequency power.

The frequency of the high frequency power is 30 MHz.
Preferably, it is z to 300 MHz.

Further, it is preferable that the impedance matching device is constituted by at least two variable capacitors.

Further, the coil has a length of substantially an integral multiple of 1/4 of the wavelength of the high-frequency power, and is constituted by a plurality of coil portions arranged point-symmetrically with respect to the coil center. Is more preferable.

In this case, it is more preferable that each of the plurality of coil portions has an arc portion located on the same circumference.

Further, it is preferable that the coil is formed in a planar spiral shape.

It is preferable that the coil is formed in a three-dimensional spiral or spiral shape.

In the plasma generating method according to the present invention, a step of introducing a gas into a chamber whose inside is maintained in a vacuum state, and a step of reducing a high-frequency power generated from a high-frequency power generation source to １ ／ of a wavelength of the high-frequency power Applying to a coil having a length that is approximately an integral multiple of the length of the high-frequency power generation source and the coil through an impedance matching device that matches the impedance of the coil, and generating a magnetic field in the coil by a high-frequency current flowing through the coil And a step of transforming the gas introduced into the chamber into a plasma by a magnetic field generated by the coil.

According to the plasma generation method of the present invention,
Since the coil has a length that is almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source, the peak value of the voltage generated in the coil increases as described above.

The plasma processing method according to the present invention includes a step of holding an object to be processed on a sample stage provided in a chamber whose inside is maintained in a vacuum state, a step of introducing a gas into the chamber, The high-frequency power generated from the power generation source is supplied to a coil having a length that is almost an integral multiple of 1/4 of the wavelength of the high-frequency power via an impedance matching device that performs impedance matching between the high-frequency power generation source and the coil. Applying a magnetic field to the coil using a high-frequency current flowing through the coil; generating a magnetic field in the coil using the magnetic field generated by the coil; and converting the gas introduced into the chamber into plasma using the magnetic field generated by the coil. And performing a process on an object to be processed held on the sample stage.

According to the plasma processing method of the present invention,
Since the coil has a length that is almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source, the peak value of the voltage generated in the coil increases as described above.

In the plasma processing method according to the present invention,
It is preferable that the method further includes a step of applying at least one of a high-frequency voltage and a constant voltage electrically insulated from the chamber to the sample stage.

In this case, it is preferable that the method further includes a step of pulse-modulating a high-frequency power applied to the coil and a step of pulse-modulating a voltage applied to the sample stage.

[0058]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a high-frequency power application device, a plasma generation device, and a plasma processing device according to each embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1A shows a schematic configuration of a plasma processing apparatus according to a first embodiment of the present invention, and FIG. 2 shows a plasma processing apparatus according to the first embodiment. 1 shows a schematic configuration of a high-frequency power application device used for the present invention.

In FIG. 1A, reference numeral 10A denotes a cylindrical chamber, and the inside of the chamber 10A is maintained at a predetermined pressure. Although not shown, the chamber 10A has gas introduction means for introducing gas into the chamber 10A, exhaust means for exhausting gas from the chamber 10A, and unloading for taking an object into and out of the chamber 10A. Inlet means are provided for each.

An insulator 1 is provided at the bottom in the chamber 10A.
1, a lower electrode (sample stage) 12 is provided.
The lower electrode 12 holds a workpiece 13 such as a semiconductor wafer on which etching or film deposition is performed.

Above the chamber 10A, a first high-frequency power supply 14 for outputting high-frequency power of, for example, a frequency of 100 MHz is provided, and four spiral coil portions 15a each having one end grounded (FIG. 1). 1 (b)
) Are electrically connected in parallel with each other. The first high frequency power supply 14 is commonly connected to each other end of the coil portion 15a via an impedance matching unit 16A.

The high-frequency power application device used in the plasma processing apparatus according to the first embodiment is a first high-frequency power supply 1
4, an impedance matching unit 16A, and a multi-spiral coil 15A.
High-frequency power generated by the impedance matching device 1
The voltage is applied to the multi-spiral coil 15A via 6A.

As a feature of the first embodiment, one of the coil portions 15a constituting the multi-spiral coil 15A
The length per book is set to 75 cm, which is １ ／ of the wavelength (3 m) of the high-frequency power supplied from the first high-frequency power supply 14.

A second high frequency power supply 17 is provided below the chamber 10A. The second high frequency power supply 17
While being electrically insulated from the chamber 10A and the insulator 11, it is electrically connected to the lower electrode 12, and applies a high frequency bias voltage to plasma generated in the chamber 10A. Second high frequency power supply 17
Is for applying a high-frequency bias voltage to the plasma generated in the chamber 10A, and the high-frequency power for generating the high-frequency bias voltage includes:
Typically, frequencies from a few hundred kHz to 13.56 MHz are used.

For the sake of safety, the ground potential of the first high-frequency power supply 14, the second high-frequency power supply 17, and the multi-spiral coil 15A is normally set to the same potential as the chamber 10A.

Hereinafter, a method for performing plasma processing using the above-described high-frequency power application device and plasma processing device will be described.

First, the object 13 is carried into the chamber 10A by carrying-in / out means (not shown) and is held on the lower electrode 12. Thereafter, the inside of the chamber 10A is maintained at a predetermined pressure by introducing a gas into the chamber 10A from a gas introduction unit (not shown) and discharging the gas from the chamber 10A by an exhaust unit (not shown).

Next, high-frequency power is applied from the first high-frequency power supply 14 to the multi-spiral coil 15A,
High frequency power is applied to the lower electrode 12 from the second high frequency power supply 17. By doing so, a high-frequency current flows through the multi-spiral coil 15A by the high-frequency power applied to the multi-spiral coil 15A, and an alternating magnetic field generated by the high-frequency current acts on the space inside the chamber 10A. Electrons existing in the space move in a direction to generate a magnetic field that cancels the magnetic field generated by the multi-spiral coil 15A. The electrons are moved by this inductive coupling, so that the chamber 1
The gas in 0A is turned into plasma. In this case, since the impedance matching unit 16 performs impedance matching with respect to the plasma, a stable plasma discharge can be generated.

By causing the plasma generated in the chamber 10A to act on the processing object 13, the processing object 13
Surface oxidation, surface nitridation and surface modification such as impurity doping,
In addition, thin film formation and isotropic dry etching on the surface of the workpiece 13 can be performed.

Further, V generated by the AC bias voltage applied to the lower electrode 12 by the second high-frequency power supply 17
When pp (Peak-to-Peak voltage) and Vdc (DC potential of the lower electrode 12) are used, ions in the plasma can be efficiently irradiated to the processing object 13, so that fine processing by anisotropic dry etching is realized. it can.

When the processing of the object 13 is completed, the supply of the high-frequency power from the first high-frequency power supply 14 and the second high-frequency power supply 17 is terminated, and then the chamber 10A
When the introduction of the gas into the chamber is completed and the residual gas in the chamber 10A is exhausted, and then, the processing target 13 is taken out of the chamber 10A, whereby the plasma processing is completed.

Hereinafter, the reason why the length of each coil portion 15a of the multi-spiral coil 15A is set to 波長 of the wavelength of the high-frequency power supplied from the first high-frequency power supply 14 will be described in detail.

In general, the wavelength becomes shorter as the frequency of the high-frequency power increases, and the wavelength effect occurs when the dimension of the object through which the high-frequency power propagates becomes closer to the wavelength of the high-frequency power. That is, when the dimension of an object through which high-frequency power propagates becomes an integral multiple of 1/4 wavelength such as 1/4 wavelength, 1/2 wavelength, or 1 wavelength of high frequency power, a kind of resonance phenomenon (resonance phenomenon) occurs. appear. Antennas and receivers actively utilize this.
Usually, the end of an antenna is an open end, and only electromagnetic waves that couple with the medium around the antenna and resonate with the structure of the antenna are radiated from the end of the antenna to the surrounding medium or from the surrounding medium to the end of the antenna. It is absorbed by.

Unlike an antenna, in a high-frequency propagation system in which a high-frequency current flows through a coil, that is, in a system in which the end of the coil opposite to the high-frequency application side is grounded, the length of the coil is the wavelength of the high-frequency power. If it is an integral multiple of 1/4, a standing wave is likely to be generated in the coil, and the peak value of the voltage generated in the coil is considered to be large. As described above, in the inductively coupled plasma generator, in a transient state before the discharge starts, electrons in the chamber are accelerated by the electric field excited in the chamber by the voltage generated in the coil. That is, the discharge starts due to the capacitive coupling, the discharge triggers the avalanche phenomenon of ionization, and when the electron density increases to a certain level, the state shifts to the inductive coupling state and the discharge is maintained. Therefore, the greater the peak value of the voltage generated in the coil, the easier the discharge starts.

As described above, when the length per coil becomes an integral multiple of 1/4 of the wavelength of the high-frequency power, a standing wave is easily generated in the coil, so that the peak value of the voltage generated in the coil decreases. It is considered that the discharge is likely to start and the plasma is likely to be generated because of the increase.

Further, it is considered that when the length of the coil is increased, the resistance component of the impedance of the coil is increased and the power efficiency is reduced, so that the discharge becomes difficult. That is, even if the length of the coil is an integral multiple of 1/4 of the wavelength of the high-frequency power, discharge is most easily started at 1/4 of the wavelength, and then discharged at 1/2 of the wavelength. The shorter the length per coil is, the easier the discharge is to start. For example, the discharge is likely to start when the wavelength is 3/4 of the wavelength.

In order to form a uniform plasma over a large area and process the object with good uniformity, the diameter of the coil needs to be about 1.5 to 2 times the diameter of the object. Come.

In order to form a uniform plasma over a large area, not only the diameter of the coil is large, but also
The number of turns of the coil is also important. When four coils having two turns are connected in parallel to form a multi-spiral coil having a multiplicity of four, uniformity equivalent to one spiral coil having eight turns can be realized.

Therefore, when a multi-spiral coil is used, the length of the coil can be shortened to easily generate plasma, and uniform plasma can be generated over a large area. That is, if a multi-spiral coil is used, the effect of the wavelength can be more effectively used.

Hereinafter, an evaluation test performed to confirm the effect of the first embodiment will be described.

C ₄ F ₈ gas is used as a gas in the chamber 10.
A and the inside of the chamber 10A is 20mTo.
Plasma was generated while maintaining rr, and a high frequency bias voltage was applied to the lower electrode 12. As a result, the silicon oxide film as the object to be processed held on the lower electrode 12 could be etched.

Next, an argon gas is introduced as a gas into the chamber 10A, and the high-frequency power supplied from the first high-frequency power supply 14 is changed to change the chamber 10A.
It was examined how high the internal pressure would start discharging. When the high frequency power is 200 W, the pressure is 24 mTo
Discharge started at rr or more, when high frequency power was 300 W, discharge started at a pressure of 20 mTorr or more, and when high frequency power was 400 W, discharge started at a pressure of 18 mTorr or more. That is, the higher the applied high frequency power, the lower the minimum pressure at which discharge started.

Next, when the high-frequency power was 200 W, 300 W, and 400 W, the minimum pressure at which discharge started was examined while variously changing the length per coil. The result is shown in FIG. As is clear from FIG.
If the magnitude of the high-frequency power is the same, the minimum pressure at which discharge starts when the coil length is ４ and 波長 of the wavelength of the high-frequency power is low, that is, in this case, discharge is likely to start. It turns out that.

FIG. 4 shows the relationship between the length per coil and the minimum pressure at which discharge starts when the length per coil is further changed. As can be seen from FIG. 4, the discharge easily starts when the length per coil is an integral multiple of 1/4 of the wavelength of the high frequency power, and is an integral multiple of 1/4 of the wavelength of the high frequency power. However, when the wavelength is 1/4, the discharge is most likely to start, when the wavelength is 1/2, the discharge is easy to start next, and when the wavelength is 3/4, the discharge starts next. Cheap. That is, the dependency of the ease of starting discharge on the length per coil becomes more pronounced as the length per coil becomes shorter. When a multi-spiral coil is used, the length of the coil can be reduced as compared with a simple spiral coil, so that it can be confirmed that discharge is more easily started.

In the description of the length of the coil in the first embodiment, the expression “an integer multiple of 波長 of the wavelength of the high-frequency power” is used. It has been confirmed that the effect is sufficient if it is approximately an integral multiple of 1/4, specifically, if it is within a range of about ± 7% with respect to an integral multiple of 1/4 of the wavelength.

(Second Embodiment) FIG. 5 shows a schematic configuration of a plasma processing apparatus according to a second embodiment of the present invention. In the second embodiment, the same members as those in the first embodiment shown in FIG.

As a feature of the second embodiment, instead of the multi-spiral coil 15A in the first embodiment,
A simple spiral coil 15B is provided. The second embodiment is disadvantageous in that a large-area plasma is formed as compared with the first embodiment, but is advantageous in that a small-area plasma is formed. Also in the second embodiment, the length of the spiral coil 15B may be approximately an integral multiple of 1/4 of the wavelength of the high-frequency power.

(Third Embodiment) FIG. 6 shows a schematic configuration of a plasma processing apparatus according to a third embodiment of the present invention. In the third embodiment, the same members as those in the first embodiment shown in FIG.

As a feature of the third embodiment, instead of the multi-spiral coil 15A in the first embodiment,
1 wound spirally on the side of the cylindrical chamber 10A
15 spiral coils 15C are provided. Also in the third embodiment, the length of the spiral coil 15C may be approximately an integral multiple of 1/4 of the wavelength of the high frequency power.

(Fourth Embodiment) FIG. 7 shows a schematic configuration of a plasma processing apparatus according to a fourth embodiment of the present invention, and FIG. 8 is used in the plasma processing apparatus according to the fourth embodiment. 1 shows a schematic configuration of a high-frequency power application device.
In the fourth embodiment, the same members as those in the first embodiment shown in FIG.

As a feature of the fourth embodiment, instead of one spiral coil 15C in the third embodiment, a multi-spiral coil 15D in which four spiral coil portions 15d are connected in parallel is provided. Is provided. According to the multi-spiral coil 15D, as in the first embodiment, each coil part 1d is multiplexed by multiplexing the coil part 15d.
The advantage that the length of 5d can be shortened is obtained. The length of each coil portion 15d connected in parallel may be approximately an integer multiple of 1/4 of the wavelength of the high-frequency power.
, The multiplicity can be 2 or more.

(Fifth Embodiment) FIG. 9 shows a schematic configuration of a plasma processing apparatus according to a fifth embodiment of the present invention. In the fifth embodiment, the same members as those in the first embodiment shown in FIG.

As a feature of the fifth embodiment, a cylindrical chamber 10B having a hemispherical dome is provided in place of the cylindrical chamber 10A in the third embodiment. Instead of the helical coil 15C having a circular shape of the same diameter in the embodiment, a plurality of circular coil portions of the same diameter located below the central portion, and located upward from the central portion and moving upward from the central portion A helical coil 15E including a plurality of circular coil portions whose diameter gradually decreases is provided. Thus, the spiral coil 15E is provided not only on the side of the workpiece 13 but also on the surface facing the workpiece 13.
Also in the fifth embodiment, the length of the spiral coil 15E may be a substantially integral multiple of 1/4 of the wavelength of the high frequency power. Further, the number of spiral coils 15E, that is, the multiplicity may be increased to form a multi-spiral coil.

(Sixth Embodiment) FIG. 10 shows a sixth embodiment of the present invention.
1 shows a schematic configuration of a plasma processing apparatus according to the embodiment. In the sixth embodiment, the same members as those in the first embodiment shown in FIG.

As a feature of the sixth embodiment, a spiral coil 15B similar to that of the second embodiment is provided, and instead of a normal impedance matching unit 16A,
Number of variable consisting of the capacitor C ₁ and C ₂ impedance matching device 16B is provided.

(Seventh Embodiment) FIG. 11 shows a seventh embodiment of the present invention.
FIG. 12 shows a schematic configuration of a plasma processing apparatus according to the seventh embodiment, and FIG. 12 shows a schematic configuration of a high-frequency power application apparatus used in the plasma processing apparatus according to the seventh embodiment. In the seventh embodiment, the same members as those in the first embodiment shown in FIG.

As a feature of the seventh embodiment, a multi-spiral coil 15A similar to that of the first embodiment is provided, and two variable capacitors C ₁ and C are used instead of the ordinary impedance matching unit 16A. ₂ is provided.

[0099] Instead of the conventional impedance matching device 16A according to the third to fifth embodiments, similarly to the first or second embodiment, two consisting of variable capacitors C ₁ and C ₂ of the impedance matching A vessel 16B may be provided.

Generally, the configuration of the impedance matching device differs as the frequency increases. Conventionally, an impedance matching device using a variable capacitor or a variable inductor is used in a frequency region of about 50 MHz or less, but in a high frequency region exceeding 50 MHz, a transient current is generated due to the difficulty of impedance matching. Since it easily flows, it is difficult to achieve impedance matching by an impedance matching device using a variable capacitor or a variable inductor. Therefore, conventionally, 100 MH
A stub has been used as an impedance matching device in a high frequency range of z or higher. However, the stub is inferior in stability, controllability and reliability. An impedance matcher is preferred.

However, in the first to fifth embodiments, the length per one coil is set to 1 / the wavelength of the high frequency power.
4, the peak value of the voltage generated in the coil becomes large. Even if high-frequency power of a high frequency exceeding 50 MHz is applied, plasma is easily generated. Therefore, two variable capacitors C _{1 are used.} and it can be used impedance matching device 16B made of C _2.

[0102] In the first to fifth embodiments, while applying the high frequency power 30~300MHz from the first RF power supply 14, the impedance matching by two variable consisting of the capacitor C ₁ and C ₂ impedance matching device 16B Then, it was found that good characteristics of impedance matching and stable plasma discharge can be obtained with good reproducibility.

(Eighth Embodiment) FIGS. 13A and 13B
Shows a schematic configuration of a high-frequency power application device according to an eighth embodiment of the present invention.

In the high-frequency power applying apparatus according to the eighth embodiment, each of the high-frequency power applying devices linearly extends outward from the center of the coil and then extends along the circumference in an arc of only 1/4 of the circumferential length. And a multi-spiral coil 15F having a structure in which four coil portions 15f, each of which is located on the same circumference, are connected in parallel, and a high-frequency power is applied to the center of the multi-spiral coil 15F. 1 high-frequency power supply 14,
And an impedance matching circuit (not shown).

In the multi-spiral coil 15F shown in FIG.
Of the first high-frequency power source 1
4 and has a length that is almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the coil 4 and a small gap between the arc portions of the coil portion 15f. FIG.
In the multi-spiral coil 15F shown in (b), the coil portion 15 of the multi-spiral coil 15F
f has a length that is almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the first high-frequency power supply 14, and the arc portions overlap each other when viewed from the radial direction. They are electrically insulated from each other. By adopting a structure in which the four coil portions 15f are connected in parallel in this way, the length per coil can be extremely reduced, as in the case of the multi-spiral coil 15A.

(Ninth Embodiment) FIG. 14 shows a ninth embodiment of the present invention.
1 shows a schematic configuration of a high-frequency power application device according to the embodiment.

In the high-frequency power applying apparatus according to the ninth embodiment, each of them extends in a curved shape outward from the center of the coil, and then extends along the circumference in an arc of only 1/4 of the circumferential length. And a multi-spiral coil 15G having a structure in which four coil portions 15g, each of which is located on the same circumference, are connected in parallel, and a high-frequency power is applied to the center of the multi-spiral coil 15G. 1 high-frequency power supply 14,
And an impedance matching circuit (not shown). Each of the coil portions 15g of the multi-spiral coil 15G has a length substantially an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the first high-frequency power supply 14. By adopting a structure in which the four coil portions 15g are connected in parallel in this manner, the multi-spiral coil 15g is used.
As in A, the length per coil can be extremely reduced.

(Tenth Embodiment) FIG. 15A,
(B) has shown the schematic structure of the high frequency electric power application apparatus which concerns on 10th Embodiment of this invention.

The high frequency power applying apparatus according to the tenth embodiment has the same shape as that of the eighth embodiment, and has a structure in which four coil portions 15f whose center portions are grounded are connected in parallel. The multi-spiral coil 15F includes four first high-frequency power supplies 14 for applying high-frequency power to the outer ends of the multi-spiral coil 15F, respectively, and an impedance matching circuit (not shown). FIG. 15 (a) corresponds to FIG. 13 (a), and FIG. 15 (b) corresponds to FIG. 13 (b).

(Eleventh Embodiment) FIG. 16 shows a schematic configuration of a plasma processing apparatus according to an eleventh embodiment of the present invention. In the eleventh embodiment, the same members as those in the first embodiment shown in FIG.

As a feature of the eleventh embodiment, a constant voltage source 18 is connected in series to a second high frequency power supply 17 for applying a high frequency bias voltage to the lower electrode 12. According to the eleventh embodiment, only the high-frequency power is
It is possible to apply only a constant voltage or both a high-frequency power and a constant voltage, and it is possible to control not only a high-frequency bias voltage but also a DC bias voltage, so that ion energy used for plasma processing can be more easily controlled. At the same time, fine adjustment and control of ion energy becomes possible. Therefore, the controllability of the plasma processing is greatly improved.

(Twelfth Embodiment) FIG. 17 shows a schematic configuration of a plasma processing apparatus according to a twelfth embodiment of the present invention. In the twelfth embodiment, the same members as those of the first embodiment shown in FIG.

As a feature of the twelfth embodiment, as in the eleventh embodiment, a constant voltage source 18 is connected in series to a second high frequency power supply 17 for applying a high frequency bias voltage to the lower electrode 12. In addition, a first pulse modulator 19 for pulse-modulating the high-frequency power applied by the first high-frequency power supply 14 is provided, and the second high-frequency power supply 1
A second pulse modulation of the bias voltage applied by
Is provided.

According to the twelfth embodiment, since the high frequency power applied by the first high frequency power supply 14 can be pulse-modulated by the first pulse modulator 19,
Compared to the eleventh embodiment, the controllability of the plasma state, such as control of the degree of dissociation of the generated plasma and control of the composition of the plasma (component ratio of radical species and ion species), is remarkably improved.

Further, by the second pulse modulator 20,
Since the high-frequency power, the constant voltage, or both the high-frequency power and the constant voltage applied by the second high-frequency power supply 17 can be pulse-modulated, only the pulse-modulated high-frequency bias voltage is pulse-modulated on the lower electrode 12. The plasma processing can be performed by applying only a DC bias voltage or both a pulse-modulated high-frequency bias and a pulse-modulated DC bias. For this reason, the controllability of the ion energy applied to the workpiece 13 is greatly improved as compared with the eleventh embodiment.

When both the first pulse modulator 19 and the second pulse modulator 20 are operated, the first pulse modulator 19 controls the degree of dissociation of the plasma and the composition of the plasma. , The second pulse modulator 20
Since the irradiation of the workpiece 13 with the ion energy or the positive / negative ion species can be controlled, the plasma processing in which radicals and ions are qualitatively and quantitatively controlled can be performed.

Further, the first pulse modulator 19 and the second
When both of the pulse modulators 20 are used, synchronizing the pulse modulation frequencies of the pulse modulators enables plasma processing with high controllability.

In the first to twelfth embodiments, a constant voltage source is connected in series to the first high frequency power supply 14 according to the contents of the plasma processing, and a DC voltage is applied to each of the coils 15A to 15G. May be.

Further, if a highly conductive metal such as copper is used as the material of the coils 15A to 15G in the first to twelfth embodiments, the coils can be manufactured at low cost.

The material for forming the coils 15A to 15G may be in any shape such as a strip, a rod, or a tube, but preferably has a large surface area. When a coil is formed from a strip-shaped material, the coil material may be used such that the thickness of the strip is opposed to the chamber or the width of the strip is opposed to the chamber. If the coil is formed so that the width of the strip faces the chamber, by changing the size of the width of the strip,
Since it becomes possible to adjust the capacitive coupling between the space in the chamber and the coil, it is possible to control the degree of inductive coupling and capacitive coupling.

Further, as a material forming the walls of the chamber, it is necessary to use a dielectric (insulator) capable of transmitting a magnetic field generated by the coil into the chamber. Materials such as (SiO ₂ ) and ceramics are preferred.

[0122]

According to the high-frequency power application apparatus or the high-frequency power application method according to the present invention, the length of the coil is set to almost an integral multiple of 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source. Since the peak value of the voltage generated at the high frequency increases, even when the frequency of the high-frequency power is high,
High-frequency power can be supplied efficiently.

In the high-frequency power application apparatus or high-frequency power application method according to the present invention, if the length of the coil is within ± 7% of an integral multiple of 波長 of the wavelength of the high-frequency power, the coil will Since the standing wave is reliably emitted, the peak value of the voltage generated by the coil can be reliably increased.

If the length of the coil is approximately ４ or １ ／ of the wavelength of the high-frequency power, the length of the coil can be short, and the resistance component of the impedance of the coil can be suppressed. The supply efficiency of high-frequency power is improved. Therefore, when this high-frequency power application device is applied to a plasma generation device, or when this high-frequency power application method is applied to a plasma generation method, discharge is easily started and plasma is easily generated.

When the length of the coil is within ± 7% of 波長 or の of the wavelength of the high frequency power,
The peak value of the voltage generated in the coil can be increased while improving the supply efficiency of the high-frequency power.

The frequency of the high-frequency power is 30 MHz or more.
Conventionally, when the frequency is 300 MHz, the reactance increases and it is difficult to achieve impedance matching, so that the supply efficiency of the high frequency power is reduced. However, according to the present invention, the high frequency power having a frequency of 30 MHz to 300 MHz is efficiently used. Can supply well. Therefore, when this high-frequency power application device is applied to a plasma generation device, or when this high-frequency power application method is applied to a plasma generation method, control of the electron temperature of plasma becomes easy.

Further, when the impedance matching device is constituted by at least two variable capacitors, the stability, controllability and reliability of the impedance matching device are improved.

Further, the coil has a frequency equal to one-half of the wavelength of the high-frequency power.
4 and is composed of a plurality of coil portions arranged point-symmetrically with respect to the center of the coil, that is, in the case of a multi-spiral coil, compared with a single continuous spiral coil, Since the length of each coil portion can be reduced, the resistance component of the impedance of the coil can be suppressed, and the efficiency of supplying high-frequency power can be improved. Therefore, when this high-frequency power application device is applied to a plasma generation device, or when this high-frequency power application method is applied to a plasma generation method, discharge is easily started and plasma is easily generated, and
Since the diameter of the coil can be easily increased, uniform plasma can be generated over a large area, so that the object to be processed can be processed with high uniformity.

In this case, if each of the plurality of coil portions has an arc portion located on the same circumference, the length of each coil portion constituting the multi-spiral coil can be further shortened. Supply efficiency can be further improved, and more uniform plasma can be generated over a large area.

Further, when the coil is formed in a planar spiral shape, when the high-frequency power applying device is applied to a plasma processing apparatus, the coil is easily opposed to the object to be processed.

Further, when the coil is formed in a three-dimensional spiral or spiral shape, it becomes easy to arrange the coil around the chamber when the high-frequency power application device is applied to a plasma processing device.

According to the plasma generating apparatus or the plasma generating method of the present invention, since the coil has a length almost an integral multiple of 1/4 of the wavelength of the high frequency power generated from the high frequency power generation source, the coil is generated. Since the peak value of the voltage increases and electrons in the chamber can be effectively accelerated, plasma can be generated under high vacuum pressure even when high frequency high frequency power is applied.

According to the plasma processing apparatus or the plasma processing method of the present invention, since the coil has a length almost an integral multiple of 1/4 of the wavelength of the high frequency power generated from the high frequency power generation source, the coil has a high frequency. Since plasma can be generated under a high vacuum pressure even when power is applied, highly uniform and low-damage plasma processing can be performed with high accuracy.

When the plasma processing apparatus according to the present invention includes voltage applying means for applying at least one of a high-frequency voltage and a constant voltage electrically insulated from the chamber to the sample stage, or In the case where the plasma processing method according to the present invention includes a step of applying at least one voltage of a high-frequency voltage and a constant voltage electrically insulated from the chamber to the sample stage, the ion energy used for the plasma processing is Control becomes easier and the ion energy can be finely adjusted and controlled, so that the controllability of the plasma processing is improved.

In this case, when the high frequency power generated from the high frequency power generation source is pulse-modulated, the controllability of the degree of dissociation of the generated plasma and the controllability of the composition of the plasma are improved. Further, when the voltage applied by the voltage applying means is pulse-modulated, a pulse-modulated high frequency bias voltage or a pulse-modulated DC bias voltage can be applied to the sample table, so that radicals and ions can be qualitatively and quantitatively controlled. Plasma processing can be performed.

[Brief description of the drawings]

FIG. 1A is a schematic configuration diagram of a plasma processing apparatus according to a first embodiment of the present invention, and FIG. 1B is a diagram illustrating a coil portion of a multi-spiral coil in the plasma processing apparatus according to the first embodiment; FIG.

FIG. 2 is a schematic configuration diagram of a high-frequency power application device used in the plasma processing apparatus according to the first embodiment.

FIG. 3 is a characteristic diagram showing a relationship between a length per one coil portion of the multi-spiral coil and a minimum pressure at which discharge starts when the high-frequency power is changed in the plasma processing apparatus according to the first embodiment. It is.

FIG. 4 is a characteristic diagram showing a relationship between a length per one coil portion of a multi-spiral coil and a minimum pressure at which discharge starts in the plasma processing apparatus according to the first embodiment.

FIG. 5 is a schematic configuration diagram of a plasma processing apparatus according to a second embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a plasma processing apparatus according to a third embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a plasma processing apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a high-frequency power application device used in the plasma processing apparatus according to the fourth embodiment.

FIG. 9 is a schematic configuration diagram of a plasma processing apparatus according to a fifth embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a plasma processing apparatus according to a sixth embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a plasma processing apparatus according to a seventh embodiment of the present invention.

FIG. 12 is a schematic configuration diagram of a high-frequency power application device used in the plasma processing apparatus according to the seventh embodiment.

FIGS. 13A and 13B are schematic configuration diagrams of a high-frequency power application device according to an eighth embodiment of the present invention.

FIG. 14 is a schematic configuration diagram of a high-frequency power application device according to a ninth embodiment of the present invention.

FIGS. 15A and 15B are schematic configuration diagrams of a high-frequency power application device according to a tenth embodiment of the present invention.

FIG. 16 is a schematic configuration diagram of a plasma processing apparatus according to an eleventh embodiment of the present invention.

FIG. 17 is a schematic configuration diagram of a plasma processing apparatus according to a twelfth embodiment of the present invention.

FIG. 18 is a schematic configuration diagram of an inductively coupled plasma processing apparatus according to a first conventional example.

FIG. 19 is a schematic configuration diagram of an inductively coupled plasma processing apparatus according to a second conventional example.

FIG. 20 is a schematic configuration diagram of an inductively coupled plasma processing apparatus according to a third conventional example.

[Explanation of symbols]

 Reference Signs List 10A, 10B Chamber 11 Insulator 12 Lower electrode 13 Workpiece 14 First high-frequency power supply 15A 15D 15F Multi spiral coil 15B Spiral coil 15C 15E Spiral coil 15a 15d 15f 15g Coil portion 16A, 16B Impedance matching device 17 Second High frequency power supply 18 constant voltage source 19 first pulse modulator 20 second pulse modulator

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 21/3065 H01L 21/302 A (72) Inventor Tomohiro Okumura 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 56) References JP-A-4-290428 (JP, A) JP-A-4-230999 (JP, A) JP-A-6-267903 (JP, A) JP-A-7-201495 (JP, A) JP Hei 3-201703 (JP, A) JP-A-6-188094 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H05H 1/46 H01L 21/3065 C23C 16/50 C23F 4 / 00

Claims (9)

(57) [Claims] 1. A high-frequency power source for generating high-frequency power, having a length substantially equal to 1/4 of the wavelength of the high-frequency power generated by the high-frequency power source, And a coil that generates a magnetic field when a high-frequency current flows, and an impedance matching device that performs impedance matching between the high-frequency power generation source and the coil , wherein the coil is point-symmetric with respect to the center of the coil. set on
And a plurality of coil parts
A high-frequency power application device formed in a three-dimensional spiral shape . 2. The high-frequency power applying apparatus according to claim 1, wherein the length of the coil is within ± 7% of an integral multiple of 波長 of the wavelength of the high-frequency power. . 3. The high-frequency power application device according to claim 1 , wherein the length of the coil is approximately １ ／ or approximately の of the wavelength of the high-frequency power. 4. The frequency of the high-frequency power is 30 MHz or more.
The high-frequency power application device according to claim 1 or 2 , wherein the frequency is 300 MHz. 5. The high-frequency power application device according to claim 1 , wherein the impedance matching device includes at least two variable capacitors. 6. A chamber whose inside is kept in a vacuum state, gas introducing means for introducing gas into the chamber, a high-frequency power generation source for generating high-frequency power, and a high-frequency power generated from the high-frequency power generation source Has a length that is approximately an integral multiple of 1/4 of the wavelength of the wavelength, and when high-frequency power is supplied from the high-frequency power source and a high-frequency current flows,
A coil for generating a magnetic field for converting a gas introduced into the chamber into a plasma, and an impedance matching device for matching impedance between the high-frequency power generation source and the coil, wherein the coil is positioned with respect to a center of the coil. Placed symmetrically
And a plurality of coil parts
A plasma processing apparatus having a three-dimensional spiral shape . 7. A chamber whose inside is maintained in a vacuum state, a sample stage provided in the chamber and holding an object to be processed, gas introducing means for introducing gas into the chamber, and high frequency power A high-frequency power generation source for generating a high-frequency power having a length substantially equal to 1/4 of the wavelength of the high-frequency power generated from the high-frequency power generation source, and receiving the high-frequency power from the high-frequency power generation source to generate a high-frequency current. As it flows,
A coil for generating a magnetic field for converting a gas introduced into the chamber into a plasma, and an impedance matching device for matching impedance between the high-frequency power generation source and the coil , wherein the coil is positioned with respect to a center of the coil. Placed symmetrically
And a plurality of coil parts
A plasma processing apparatus having a three-dimensional spiral shape . 8. to claim 7, characterized in that it further comprises a voltage applying means for applying at least one voltage of said chamber and electrically insulated high-frequency voltage and a constant voltage to the sample stage The plasma processing apparatus as described in the above. 9. A first pulse modulator for pulse-modulating high-frequency power generated from the high-frequency power generation source, and a second pulse modulator for pulse-modulating a voltage applied by the voltage applying means.
And a pulse modulator of
A plasma processing apparatus according to claim 8 .