WO2012176242A1

WO2012176242A1 - Plasma processing device

Info

Publication number: WO2012176242A1
Application number: PCT/JP2011/003618
Authority: WO
Inventors: 角田　孝典; 克夫松原; 靖典安東; 蔵行辻
Original assignee: 日新電機株式会社
Priority date: 2011-06-24
Filing date: 2011-06-24
Publication date: 2012-12-27

Abstract

Provided is an inductively coupled plasma processing device in which the effective inductance of an antenna can be reduced, the plasma potential can be kept low, and the plasma density distribution in the longitudinal direction of the antenna can be controlled by the antenna. In the plasma processing device, an antenna (30) having a straight, planar shape is configured from reciprocating conductors (31, 32) arranged in proximity to each other in a vertical direction (Z), which is a perpendicular (3) erected to the surface of a substrate (2). High-frequency currents (I_R) flow in mutually opposite directions through the conductors. The width (W) of the conductor (32) on the side opposite from that where a plasma (50) is located is varied in the longitudinal (X) direction of the antenna (30).

Description

Plasma processing equipment

The present invention relates to a plasma processing apparatus that performs processing such as film formation by plasma CVD, etching, ashing, sputtering, etc. on a substrate using plasma. More specifically, the present invention is generated by applying a high-frequency current to an antenna. The present invention relates to an inductively coupled plasma processing apparatus that generates plasma by an induced electric field and performs processing on a substrate using the plasma.

As belonging to a plasma processing apparatus that generates high-frequency plasma, a capacitively coupled plasma processing apparatus that generates capacitively coupled plasma (abbreviated as CCP) and an inductively coupled type that generates inductively coupled plasma (abbreviated as ICP) Plasma processing apparatus.

In brief, the capacitively coupled plasma processing apparatus applies a high-frequency voltage between two parallel electrodes and generates plasma using a high-frequency electric field generated between the two electrodes.

In this capacitively coupled plasma processing apparatus, a high voltage is applied to the plasma to increase the plasma potential, and charged particles (for example, ions) in the plasma impinge on and collide with the substrate with high energy, so that they are formed on the substrate. There are problems such as increased damage to the film and deterioration of the film quality.

On the other hand, an inductively coupled plasma processing apparatus, in simple terms, generates plasma by an induced electric field generated by flowing a high-frequency current through an antenna. There is an advantage that it can be lowered.

As an example of such an inductively coupled plasma processing apparatus, Patent Document 1 discloses that a flat antenna is attached to an opening of a vacuum vessel via an insulating frame, and a high-frequency power source is connected between one end and the other end of the antenna. A plasma processing apparatus is described in which a high-frequency power is supplied to flow a high-frequency current, plasma is generated by an induced electric field generated thereby, and a substrate is processed using the plasma.

International Publication No. WO 2009/142016 (paragraphs 0024-0026, FIG. 1)

Also in an inductively coupled plasma processing apparatus, when an antenna is lengthened to cope with a large substrate, the impedance (particularly inductance) of the antenna increases, thereby generating a large potential difference between both ends of the antenna.

Since the potential of this antenna is reflected in the plasma potential via the capacitance between the antenna and the plasma, the plasma potential increases as the antenna potential increases. As a result, charged particles (for example, ions) in the plasma impinge and collide with the substrate with high energy, so that damage to the film formed on the substrate is increased and the film quality is deteriorated.

Therefore, the present invention is an inductively coupled device that can reduce the effective inductance of the antenna to suppress the plasma potential, and can control the plasma density distribution in the longitudinal direction by the antenna. The main purpose is to provide a device.

The plasma processing apparatus according to the present invention generates a plasma by generating an induction electric field in a vacuum vessel by flowing a high-frequency current through an antenna having a substantially straight planar shape, and processes the substrate using the plasma. An inductively coupled plasma processing apparatus, wherein the antenna is configured by a reciprocating conductor that is disposed close to each other in a direction along a vertical line standing on a surface of the substrate and in which the high-frequency currents flow in opposite directions. The width of at least one of the reciprocating conductors is varied in the longitudinal direction of the antenna.

In the following, in order to simplify the expression, the direction along the vertical line standing on the surface of the substrate is referred to as the vertical direction, and the direction intersecting the vertical line is referred to as the horizontal direction. Accordingly, the vertical direction is not necessarily the vertical direction.

In this plasma processing apparatus, the antenna is constituted by reciprocating conductors that are arranged close to each other in the vertical direction and in which high-frequency currents flow in opposite directions. Effective inductance is reduced. Therefore, the potential of the antenna can be kept low, and the plasma potential can be kept low.

Moreover, by changing the width of at least one of the reciprocating conductors in the longitudinal direction of the antenna, the area where the reciprocating conductors face each other is varied in the longitudinal direction of the antenna. Thereby, since the mutual inductance between the reciprocating conductors can be changed in the longitudinal direction of the antenna, the electromagnetic energy supplied from the antenna to the plasma can be changed in the longitudinal direction of the antenna. Therefore, the plasma density distribution in the longitudinal direction can be controlled by this antenna.

The width of the conductor on the side opposite to the plasma of the reciprocating conductor may be smaller than the width of the central portion in the longitudinal direction of the antenna.

According to the first aspect of the present invention, the antenna is constituted by the reciprocating conductors that are arranged close to each other in the vertical direction and in which the high-frequency currents flow in opposite directions. Perhaps the effective inductance of the antenna is reduced. Therefore, the potential of the antenna can be kept low, and the plasma potential can be kept low. As a result, the energy of charged particles incident on the substrate from the plasma can be reduced. Thereby, for example, damage to the film formed on the substrate can be suppressed to a small level, and the film quality can be improved. Further, even when the antenna is lengthened, the plasma potential can be kept low by keeping the antenna potential low for the above reasons, so that it becomes easy to cope with the increase in size of the substrate by lengthening the antenna.

Moreover, by changing the width of at least one of the reciprocating conductors in the longitudinal direction of the antenna, the area where the reciprocating conductors face each other is varied in the longitudinal direction of the antenna. Thereby, since the mutual inductance between the reciprocating conductors can be changed in the longitudinal direction of the antenna, the electromagnetic energy supplied from the antenna to the plasma can be changed in the longitudinal direction of the antenna. Therefore, the plasma density distribution in the longitudinal direction can be controlled by this antenna. As a result, the processing state of the substrate in the longitudinal direction of the antenna can be controlled. For example, the film thickness distribution in the longitudinal direction of the antenna can be controlled.

The invention according to claim 2 has the following further effects. That is, the plasma density distribution in the longitudinal direction of the antenna is usually a mountain-shaped distribution in which the plasma density at both ends is smaller than that at the center. On the other hand, as in the present invention, the width of the conductor on the side opposite to the plasma of the reciprocating conductor is made smaller than the width of the central portion in the longitudinal direction of the antenna, thereby making the longitudinal direction of the antenna Since the mutual inductance at both ends can be made smaller than that at the center, the effective inductance at both ends is relatively greater than that at the center of the antenna. As a result, the electromagnetic energy supplied to the plasma from the antenna can be made relatively large near both ends rather than near the center in the longitudinal direction of the antenna, as opposed to the chevron. The distribution can be corrected to increase the uniformity of the plasma density distribution in the longitudinal direction of the antenna. As a result, the uniformity of substrate processing in the longitudinal direction of the antenna can be improved. For example, the uniformity of the film thickness distribution in the longitudinal direction of the antenna can be improved.

According to the invention described in claim 3, the following further effects are obtained. That is, since the plurality of antennas arranged in parallel with each other and supplied with high-frequency power in parallel are provided, plasma having a larger area can be generated. In addition, the potential of each antenna can be kept low by the above action, and the plasma density distribution in the longitudinal direction of each antenna can be controlled. Furthermore, since a variable impedance is interposed in each antenna and the balance of the high-frequency current flowing through the plurality of antennas can be adjusted by the variable impedance, it is possible to control the plasma density distribution in the parallel direction of the plurality of antennas. it can. As a result, the plasma potential can be kept low, and it is possible to generate a plasma with a larger area and a better plasma density distribution.

It is sectional drawing which shows one Embodiment of the plasma processing apparatus which concerns on this invention. 2A and 2B are diagrams illustrating an antenna in FIG. 1, in which FIG. 1A is a plan view, FIG. 1B is a side view, and FIG. It is a figure which shows the other example of the cross-sectional shape of the plate-shaped reciprocating conductor arrange | positioned at an up-down direction. It is a figure which shows the schematic example of the plasma density distribution in the longitudinal direction at the time of using a well-known simple planar antenna. It is a figure for demonstrating the impedance etc. of the reciprocating conductor which has mutually approached. It is a schematic side view which shows the example of the antenna made into center feeding. It is a schematic plan view showing an example in which a plurality of antennas are arranged in parallel. It is a schematic side view which shows other embodiment of the plasma processing apparatus which concerns on this invention.

An embodiment of the plasma processing apparatus according to the present invention is shown in FIG. 1, and the antenna 30 is extracted and shown in FIG. In order to indicate the orientation of the antenna 30 and the like, the X direction, the Y direction, and the Z direction that are orthogonal to each other at one point are shown in the drawing. The Z direction is a direction along (for example, parallel to) the perpendicular 3 standing on the surface of the substrate 2, and the Y direction is a direction that intersects (for example, orthogonal to) the perpendicular 3, and these are expressed as described above. For simplification, they will be referred to as the vertical direction Z and the horizontal direction Y, respectively. The X direction is a direction that intersects (for example, is orthogonal to) the perpendicular 3 and is a longitudinal direction of the antenna 30. For example, the X direction and the Y direction are horizontal directions, but are not limited thereto. The same applies to the other drawings.

This apparatus, by generating an induced electric field in the vacuum vessel 4 to produce a plasma 50 by the induced electric field by the planar shape frequency current I _R from the high frequency power source 42 in a substantially straight antenna 30, the plasma 50 is an inductively coupled plasma processing apparatus for processing the substrate 2 using 50.

“Substantially straight” means not only literally straight, but also includes a state that is almost straight (almost straight).

The substrate 2 is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic EL display, a flexible substrate for a flexible display, a substrate for a semiconductor device such as a solar cell, or the like. is not.

The planar shape of the substrate 2 is, for example, a circle or a rectangle, and is not limited to a specific shape.

The treatment applied to the substrate 2 is, for example, film formation by plasma CVD, etching, ashing, sputtering, or the like.

This plasma processing apparatus is also called a plasma CVD apparatus when a film is formed by plasma CVD, a plasma etching apparatus when etching is performed, a plasma ashing apparatus when ashing is performed, and a plasma sputtering apparatus when sputtering is performed.

This plasma processing apparatus includes, for example, a metal vacuum vessel 4 and the inside thereof is evacuated by a evacuation apparatus 8.

A gas 24 is introduced into the vacuum vessel 4 through a gas introduction pipe 22. The gas 24 may be set according to the processing content applied to the substrate 2. For example, when forming a film on the substrate 2 by the plasma CVD method, the gas 24 is a source gas or a gas obtained by diluting it with a diluent gas (for example, H ₂ ). More specifically, an Si film is formed on the surface of the substrate 2 when the source gas is SiH _4, an SiN film is formed when SiH ₄ + NH ₃ is used, and an SiO ₂ film is formed when SiH ₄ + O ₂ is used. be able to.

In the vacuum vessel 4, a holder 10 that holds the substrate 2 is provided. In this example, the holder 10 is supported by the shaft 16. A bearing portion 18 having an electrical insulation function and a vacuum sealing function is provided at a portion where the shaft 16 penetrates the vacuum container 4. As in this example, a negative bias voltage may be applied to the holder 10 from the bias power source 20 via the shaft 16. The bias voltage may be a negative pulse voltage. With such a bias voltage, for example, the energy when positive ions in the plasma 50 are incident on the substrate 2 can be controlled to control the crystallinity of the film formed on the surface of the substrate 2.

The antenna 30 is provided in the opening 7 of the ceiling surface 6 of the vacuum vessel 4 with an insulating frame 38 interposed therebetween. Between these elements, a packing 40 for vacuum sealing is provided. The antenna 30 is composed of

reciprocating conductors

31 and 32 arranged close to each other in the vertical direction Z. In this example, the planar shape of the antenna 30 (more specifically, the

reciprocating conductors

31 and 32 constituting the antenna 30) is planar. The antenna 30 will be described in detail later.

The material of the antenna 30 is, for example, copper (more specifically, oxygen-free copper), aluminum, or the like, but is not limited thereto.

More specifically, high-frequency power is supplied to the antenna 30 from the high-frequency power source 42 via the matching circuit 44 to the

reciprocating conductors

31 and 32, whereby a high-frequency current I _R flows through the antenna 30. That is, the

reciprocating conductors

31 and 32 constituting the antenna 30 opposite the high-frequency current (return current) I _R is passed through each other (because the high frequency, the direction of the high-frequency current I _R is inverted by the time. Hereinafter the same) . The high frequency current I _R generates a high frequency magnetic field around the antenna 30, thereby generating an induction electric field in a direction opposite to the high frequency current I _R. Due to this induced electric field, electrons are accelerated in the vacuum vessel 4 to ionize the gas 24 in the vicinity of the antenna 30 and generate plasma 50 in the vicinity of the antenna 30. The plasma 50 diffuses to the vicinity of the substrate 2, and the above-described processing can be performed on the substrate 2 by the plasma 50.

The frequency of the high-frequency power output from the high-frequency power source 42 is, for example, a general 13.56 MHz, but is not limited thereto.

The antenna 30 will be described in detail. As shown in FIG. 5, the total impedance Z _T of the

parallel reciprocating conductors

61 and 62 that are close to each other is expressed by the following equation as described in the book of electrical theory as a differential connection. . Here, R ₁ and L ₁ are the resistance and self-inductance of one conductor 61, respectively, R ₂ and L ₂ are the resistance and self-inductance of the other conductor 62, and M is between the two

conductors

61 and 62, respectively. Mutual inductance.

[Equation 1]
Z _T = (R ₁ + R ₂ ) + j (L ₁ + L ₂ −2M)

Here, to simplify the _{_{description, R 1 = R 2 = R}} , When L ₁ = L ₂ = L, total impedance Z _T is represented by the number 2, in the inductance L _T is the number 3 of which expressed. As in the inductance L _T, a material obtained by combining the self and mutual inductances, in this specification will be referred to as effective inductance.

[Equation 2]
Z _T = 2R + j2 (LM)

[Equation 3]
L _T = 2 (LM)

As can be seen from the above equation, the mutual inductance M between the

reciprocating conductors

61 and 62 is increased, total impedance Z _T and the effective inductance L _T is reduced. The electromagnetic energy G generated by flowing a high-frequency current I _R from the high-frequency power source 42 to the

reciprocating conductors

61 and 62 is expressed by the following equation. Therefore, when the mutual inductance M increases, the electromagnetic energy G decreases, The acting magnetic effect is reduced. In the case of plasma generation, the electromagnetic energy that can be supplied to the plasma decreases and the plasma density decreases. The reverse case is the opposite.

[Equation 4]
_{G = (1/2) L T I} R 2
= (LM) I _R ²

When the mutual inductance M is not uniform in the longitudinal direction of the

reciprocating conductors

61 and 62, that is, when the mutual inductance M is changed (in other words, changed), if each region is viewed, Depending on the mutual inductance M, the effective inductance and electromagnetic energy are determined.

The antenna 30 constituting the present invention applies the above principle. That is, by changing the width of at least one of the

reciprocating conductors

31 and 32 constituting the antenna 30 in the longitudinal direction X of the antenna 30, the area where the

reciprocating conductors

31 and 32 face each other is changed to the longitudinal direction of the antenna 30. X is changed. Accordingly, the mutual inductance M between the

reciprocating conductors

31 and 32 is changed in the longitudinal direction X of the antenna 30. In this specification, the widths of the

conductors

31 and 32 refer to the width in the left-right direction Y (that is, the direction orthogonal to the longitudinal direction X).

An example embodying this is the antenna 30 shown in FIGS. The antenna 30 will be described in detail. The antenna 30 includes

reciprocating conductors

31 and 32 that are arranged close to each other in the vertical direction Z. The lower surface of the conductor 31 on the lower side (that is, the plasma 50 side) is located in the vacuum atmosphere in the vacuum vessel 4, and the conductor 32 on the upper side (that is, the side opposite to the plasma 50) is located in the atmosphere. One end of each of the

conductors

31 and 32 is electrically open, and an insulator 36 is provided there in this example. The other end portions are electrically connected to each other at the connection portion 33. High-frequency power is supplied from one high-frequency power source 42 via a matching circuit 44 between one end portions of both the

conductors

31 and 32.

Both

conductors

31 and 32 are flat in this example. In this case, for example, the thickness of the lower conductor 31 may be increased as in the example shown in FIGS. 1 and 2C, or the thickness of both the

conductors

31 and 32 as in the example shown in FIG. The sizes may be similar to each other.

In this example, the lower conductor 31 has a rectangular planar shape, and its width is constant in the longitudinal direction X.

In this example, the upper conductor 32 is formed by gradually reducing the widths W ₁ and W ₃ of the regions A ₁ and A ₃ at both ends from the width W ₂ of the central region A ₂ in the longitudinal direction X. Yes. More specifically, W ₁ = W ₃ <W ₂ . The reason why the width W of the upper conductor 32 is changed is that it is more advantageous for generating a plasma with a larger area if the width of the conductor 31 on the plasma side is not changed. Further, the disturbance of the magnetic field on the plasma side can be reduced.

When the width W of the conductor 32 is changed as described above, the areas S ₁ to S ₃ where the

reciprocating conductors

31 and 32 face each other change in each of the regions A ₁ to A ₃ . That is, S ₁ = S ₃ <S ₂ . As a result, mutual inductance M ₁ ~ M ₃ of the areas A ₁ ~ A ₃ is a _{_{_{M 1 = M 3 <M 2}}} . Therefore, as can be seen by referring to Equation ₃ , the effective inductances of the regions A ₁ and A ₃ are larger than those of the region A ₂ . The magnetic flux densities B ₁ to B ₃ are B ₁ = B ₃ > B ₂ . As a result, the electromagnetic energy supplied from the antenna 30 to the plasma can be made relatively larger in the regions A ₁ and A _{3 at} both ends than in the region A ₂ at the center.

The width W and the mutual inductance M of the conductor constituting the antenna 30 may be changed stepwise as in the above example in the longitudinal direction X of the antenna 30 or may be changed continuously. The same applies to other examples described below. Even if the width W or the like is changed stepwise, the plasma density can be smoothly changed because the plasma has a diffusing action. For example, the upper conductor 32 shown in FIG. 1 and FIG. 2 is formed into a gentle shape with a bulged central portion, and the width W and the mutual inductance M of the conductor constituting the antenna 30 are continuously changed in the longitudinal direction X of the antenna 30. It may be changed.

Instead of the antenna 30 shown in FIGS. 1 and 2, an antenna 30 having the structure shown in FIG. 6 may be provided.

The example shown in FIG. 6 is a modification of the example shown in FIGS. That is, instead of supplying high-frequency power from the end of the antenna 30 (end feeding) as in the examples shown in FIGS. 1 and 2, high-frequency power is supplied from the center of the antenna 30 as in the example shown in FIG. (Central feeding) may be used. The width W of the upper conductor 32 in this example is changed in the same manner as shown in FIG.

In the examples shown in FIGS. 6 and 8, the matching circuit is omitted for the sake of simplification. Usually, like the example shown in FIG. 1, the high-frequency power source 42 and the antenna 30 are not connected. A matching circuit 44 is provided.

In the plasma processing apparatus according to the present invention, the antenna 30 is constituted by the

reciprocating conductors

31 and 32 that are arranged close to each other in the vertical direction Z and in which the high-frequency currents I _R flow in opposite directions. As can be seen from Equation 3, the effective inductance of the antenna 30 is reduced by the mutual inductance between the

reciprocating conductors

31 and 32. Since the impedance of the antenna 30 is mostly an inductance in the high frequency region, the effective inductance is reduced, so that the potential difference generated in the antenna 30 is reduced, the potential of the antenna 30 is reduced, and the potential of the plasma 50 is reduced. Can be suppressed.

As a result, the energy of charged particles (for example, ions) incident on the substrate 2 from the plasma 50 can be kept small. Thereby, for example, when a film is formed on the substrate 2 by the plasma 50, damage to the film can be suppressed to be small, and the film quality can be improved. Further, even when the antenna 30 is lengthened, the plasma potential can be kept low by keeping the potential of the antenna 30 low for the above reasons. Therefore, it is easy to cope with the increase in size of the substrate 2 by lengthening the antenna 30. Become.

In addition, by changing the width of at least one of the

reciprocating conductors

31 and 32 in the longitudinal direction X of the antenna, the area S where the

reciprocating conductors

31 and 32 face each other is varied in the longitudinal direction X of the antenna 30. Thereby, the mutual inductance M between the

reciprocating conductors

31 and 32 can be changed in the longitudinal direction X of the antenna 30, so that the electromagnetic energy supplied from the antenna 30 to the plasma 50 is changed in the longitudinal direction X of the antenna 30. be able to. Therefore, the plasma density distribution in the longitudinal direction X can be controlled by the antenna 30. As a result, the processing state of the substrate in the longitudinal direction X of the antenna 30 can be controlled. For example, when a film is formed on the substrate 2 by the plasma 50, the film thickness distribution in the longitudinal direction X of the antenna 30 can be controlled.

The cross-sectional shape of the

reciprocating conductors

31 and 32 constituting the antenna 30 is not limited to the illustrated example. Alternatively, a structure may be adopted in which the

conductors

31 and 32 are made hollow and a coolant such as cooling water is passed therethrough to forcibly cool the

conductors

31 and 32.

By the way, normally, that is, when a known simple planar antenna is used, the plasma density distribution in the longitudinal direction X is smaller than the plasma density at the center part as shown in FIG. 4, for example. It becomes a mountain-shaped distribution. The reason for this will be briefly explained. The plasma diffuses from the left and right sides in the central portion, whereas the plasma diffuses only from one side at both ends.

On the other hand, the width W of the conductor 32 on the upper side (that is, the side opposite to the plasma 50) is set to the width of the central portion in the longitudinal direction X of the antenna 30 as in the examples shown in FIGS. By reducing the width at both ends, the mutual inductance at both ends can be made smaller than that at the center in the longitudinal direction X of the antenna 30. The effective inductance of the part becomes relatively large. As a result, the electromagnetic energy supplied from the antenna 30 to the plasma 50 is made relatively larger near both ends than near the center in the longitudinal direction X of the antenna 30, contrary to the mountain shape, and more than near the center. Since the plasma 50 can be generated more strongly in the vicinity of both ends, the above-mentioned peak-shaped plasma density distribution can be corrected, and the uniformity of the plasma density distribution in the longitudinal direction X of the antenna 30 can be improved. As a result, the uniformity of substrate processing in the longitudinal direction of the antenna 30 can be improved. For example, when a film is formed on the substrate 2 by the plasma 50, the uniformity of the film thickness distribution in the longitudinal direction X of the antenna 30 can be improved.

In addition, you may provide the shielding board 46 which shields the surface inside the vacuum vessel 4 of the antenna 30 from the plasma 50 like embodiment shown in FIG. The shielding plate 46 is made of an insulating material. The shielding plate 46 may be attached directly near the entrance of the opening 7 of the ceiling surface 6 of the vacuum vessel 4 or may be attached using a frame-like support plate 48 as in this embodiment. Even when the antenna 30 other than the example shown in FIG. 1 is used, such a shielding plate 46 may be provided.

The material of the shielding plate 46 is, for example, quartz, alumina, silicon carbide, silicon or the like. If it is difficult to reduce oxygen by hydrogen plasma and release oxygen from the shielding plate 46, a non-oxide material such as silicon or silicon carbide may be used. For example, it is easy to use a silicon plate.

If the shielding plate 46 is provided, the surface of the antenna 30 or the like is sputtered by charged particles (mainly ions) in the plasma 50, and metal contamination (metal contamination) occurs in the plasma 50 and the substrate 2. Occurrence can be prevented.

Even if the shielding plate 46 is provided, the shielding plate is made of an insulating material and cannot prevent the potential of the antenna 30 from reaching the plasma 50. Therefore, as described above, the effective inductance of the antenna 30 is reduced to reduce the antenna 30. It is effective to keep the potential of

As shown in the example of FIG. 7, a plurality of antennas 30 having the above-described configuration are arranged in parallel with each other in the Y direction, and the plurality of antennas 30 are connected to each antenna 30 via variable impedances 52 connected in series. Alternatively, high frequency power may be supplied in parallel from a common high frequency power source 42.

Each antenna 30 may have any of the configurations described above with reference to FIGS.

The variable impedance 52 may be a variable inductance as shown in FIG. 7, a variable capacitor (variable capacitance), or a mixture of both. By inserting the variable inductance, it is possible to increase the impedance of the power feeding circuit, and thus it is possible to suppress the current of the antenna 30 through which a high-frequency current flows excessively. By inserting a variable capacitor, when the inductive reactance is large, the capacitive reactance can be increased and the impedance of the power feeding circuit can be decreased. Therefore, the current of the antenna 30 in which high-frequency current hardly flows can be increased. .

In the case of the example shown in FIG. 7, since a plurality of antennas 30 are arranged in parallel with each other and high-frequency power is supplied in parallel, a plasma with a larger area can be generated. In addition, the potential of each antenna 30 can be kept low by the above action, and the plasma density distribution in the longitudinal direction X of each antenna 30 can be controlled. Furthermore, since the variable impedance 52 is interposed in each antenna 30 and the balance of the high-frequency current flowing through the plurality of antennas 30 can be adjusted by the variable impedance 52, the plasma density distribution in the parallel direction Y of the plurality of antennas 30 can be adjusted. Can also be controlled. As a result, the plasma potential can be kept low, and it is possible to generate a plasma with a larger area and a better plasma density distribution.

Each of the above examples is an example in the case where the substrate 2 is fixed without moving in the vacuum vessel 4 and the process is performed. However, as in the example shown in FIG. , While the substrate 2 is being conveyed by the substrate conveying device 54 in a direction crossing (for example, orthogonal to) the longitudinal direction X of the antenna 30, that is, in a direction along the Y direction, as indicated by an arrow F (or the opposite direction). The substrate 2 may be processed. By doing so, the uniformity of the plasma 50 in the X direction can be enhanced by the above-described configuration of the antenna 30, and the uniformity of the plasma 50 in the Y direction does not become a significant problem due to the substrate transport. Can be processed with good uniformity. It is also possible to process a plurality of substrates 2 continuously. The antenna 30 in this case may have any configuration described above with reference to FIGS. Further, the idea of conveying the substrate 2 and the idea of arranging the plurality of antennas 30 shown in FIG. 7 may be used in combination.

2 Substrate 4 Vacuum container 24 Gas 30

Antenna

31 and 32 Reciprocating conductor 42 High frequency power supply 50 Plasma 52 Variable impedance

Claims

This is an inductively coupled plasma processing apparatus for generating a plasma by generating an induction electric field in a vacuum vessel by flowing a high-frequency current through an antenna having a substantially straight planar shape, and processing the substrate using the plasma. And
The antenna is arranged close to each other in a direction along a vertical line standing on the surface of the substrate, and is constituted by a reciprocating conductor in which the high-frequency currents flow in opposite directions,
The plasma processing apparatus is characterized in that the width of at least one of the reciprocating conductors is changed in the longitudinal direction of the antenna.
The plasma processing apparatus according to claim 1, wherein the width of the conductor on the side opposite to the plasma of the reciprocating conductor is smaller than the width of the central portion in the longitudinal direction of the antenna.
A plurality of the antennas, which are arranged in parallel with each other;
3. The plasma processing apparatus according to claim 1, wherein high-frequency power is supplied in parallel from a common high-frequency power source to the plurality of antennas via a variable impedance connected in series to each of the antennas. .