JP2012226888A - Plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inductively-coupled plasma processing apparatus capable of enhancing uniformity of plasma density distribution in a longitudinal direction of an antenna.SOLUTION: A plasma processing apparatus has an antenna 30 in which a high-frequency current Iis flowed from one end part to the other end part in an X direction. Unevenness in a vertical direction is provided to a lower surface 33 of the antenna 30, and more convex parts 35 are arranged in the vicinity of both end parts rather than the center part in the X direction in the antenna 30. A comb-like shield conductor 60 for shielding an electric field between the antenna 30 and a plasma 50 is provided downward the antenna 30. The shield conductor 60 has in the X direction a plurality of linear conductors 62 parallel to a Y direction, and an electrically-grounded connection conductor electrically connecting one end parts in the Y direction of the plurality of linear conductors 62 in parallel.

Description

  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 conductors and generates plasma using a high frequency electric field generated between the two conductors.

  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)

  When plasma is generated using a conventional simple flat antenna as described in Patent Document 1, the plasma density distribution in the longitudinal direction is, for example, as shown in FIG. Also has a mountain-shaped distribution with a small plasma density at both ends. 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.

  As a result, the uniformity of substrate processing in the longitudinal direction of the antenna decreases. For example, when a film is formed on a substrate, the film thickness distribution in the longitudinal direction of the antenna is a mountain-shaped distribution with a large film thickness at the center, similar to the plasma density distribution, and the film thickness distribution is uniform. descend.

  The above problems become more prominent as the antenna becomes longer in order to cope with a large substrate.

  Accordingly, the main object of the present invention is to improve the uniformity of the plasma density distribution in the longitudinal direction of the antenna in the inductively coupled plasma processing apparatus.

  The plasma processing apparatus according to the present invention is an inductively coupled plasma processing apparatus that generates plasma by generating an induction electric field in a vacuum vessel by flowing a high-frequency current through an antenna, and performs processing on a substrate using the plasma. If the two directions orthogonal to each other are defined as an X direction and a Y direction, the antenna has a dimension in the X direction that is larger than a dimension in the Y direction. A high-frequency current flows, and the lower surface, which is the surface inside the vacuum vessel, of the antenna is provided with unevenness in the vertical direction, and more protrusions are arranged near both ends than the central portion in the X direction of the antenna. And a comb-shaped shield conductor that is electrically insulated from the antenna and shields the electric field between the antenna and the plasma below the antenna. The shield conductor is a conductor that has a plurality of linear conductors each in the X direction parallel to the Y direction, and electrically connects one end of the plurality of linear conductors in the Y direction in parallel. And a connection conductor that is electrically grounded.

  When a high-frequency current is passed through the antenna, the high-frequency current mainly flows through the surface layer of the antenna due to the skin effect. Therefore, if the lower surface of the antenna is uneven, the high-frequency current flows along a path wavy in the vertical direction along the unevenness. As a result, since the high frequency power can be supplied to the plasma from a closer location in the convex portion, if the convex portion is arranged as described above, it is stronger near both ends than the central portion in the X direction of the antenna. Plasma can be generated. As a result, the uniformity of the plasma density distribution in the longitudinal direction of the antenna can be improved.

  On the other hand, if the antenna has irregularities, the high-frequency current flows along the corrugated path as described above, so that the effective path length of the high-frequency current increases, and the antenna impedance (particularly the inductance) ) Increases, thereby increasing the potential difference between both ends of the antenna. If no countermeasure is taken, the potential of this antenna is reflected in the plasma via the electrostatic capacitance between the antenna and the plasma potential. However, in the present invention, since the electric field between the antenna and the plasma can be shielded by the shield conductor, the influence of the antenna potential on the plasma potential can be suppressed to a low level and the plasma potential can be suppressed low.

  The convex portion of the antenna may protrude greatly downward as approaching both ends in the X direction of the antenna, or may be relatively rough at the center in the X direction of the antenna and relatively dense near both ends. It may be arranged.

  According to invention of Claims 1-3, there exists the following effect. That is, if the above-described unevenness is provided on the antenna, plasma can be generated more strongly in the vicinity of both end portions than in the central portion in the X direction of the antenna, so that the plasma density distribution in the longitudinal direction of the antenna is uniform. Can increase the sex. 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. Therefore, it becomes easy to cope with the increase in the size of the substrate by lengthening the antenna.

  On the other hand, if the antenna is uneven, the impedance (particularly inductance) of the antenna increases, thereby increasing the potential difference between both ends of the antenna. If no countermeasure is taken, the potential difference of the antenna is reflected in the plasma via the electrostatic capacitance with the plasma, so that the plasma potential is also increased. However, in the present invention, since the electric field between the antenna and the plasma can be shielded by the shield conductor, the influence of the antenna potential on the plasma potential can be suppressed to a low level and the plasma potential can be suppressed 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 antenna potential can be kept low and the plasma potential can be kept low for the above reasons, so that the antenna can be lengthened to cope with the increase in size of the substrate.

  In addition, each linear conductor constituting the comb-shaped shield conductor is arranged in a direction orthogonal to the longitudinal direction of the antenna and is linear and has a small area, so that the area between the shield conductor and the antenna and the plasma is small. Capacitance can be reduced. Therefore, it can be suppressed that the shield conductor becomes a kind of intermediate conductor and the effect of suppressing the plasma potential is lowered. Furthermore, each linear conductor constituting the shield conductor is arranged in a direction orthogonal to the high-frequency current flowing through the antenna, and does not interlink with the magnetic flux generated by the high-frequency current, and the entire shield conductor has a comb shape. Since no closed loop is formed, it is possible to suppress the occurrence of high-frequency power loss due to circulating current flowing in the shield conductor. Furthermore, since each linear conductor which comprises a shield conductor is linear and its area is small, it can suppress that they act as a high frequency magnetic shield. Therefore, the electromagnetic energy from the antenna can be efficiently used for plasma generation without being shielded as much as possible by the shield conductor.

  As described above, the unevenness of the plasma density distribution in the longitudinal direction of the antenna is improved by using the combination of the unevenness as described above on the lower surface of the antenna and the above-described comb-shaped shield conductor. In addition, the plasma potential can be kept low, and even if a shield conductor is provided, high-frequency power radiated from the antenna can be efficiently used for plasma generation.

  According to invention of Claim 4, there exists the following further effect. 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 above-described action can improve the uniformity of the plasma density distribution in the longitudinal direction of each antenna. Furthermore, since the 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, the uniformity of the plasma density distribution in the parallel direction of the plurality of antennas can be improved. can do. As a result, it is possible to generate a plasma having a larger area and good uniformity of the plasma density distribution.

  In addition, since the comb-shaped shield conductor has a size corresponding to a plurality of antennas, the effect of the antenna potential on the plasma potential can be suppressed to a low level by the same action as described above. it can. Furthermore, since it is possible to suppress the occurrence of high-frequency power loss due to circulating current flowing in the shield conductor, the high-frequency power can be efficiently used for plasma generation.

It is a figure which shows the schematic example of the plasma density distribution in the longitudinal direction at the time of using the conventional simple flat antenna. It is sectional drawing which shows one Embodiment of the plasma processing apparatus which concerns on this invention. It is a figure which shows the antenna, shield conductor, etc. in FIG. 1, (A) is the electric potential distribution figure of an antenna, (B) is a side view, (C) is a bottom view. It is a figure which shows the other example of an antenna and a shield conductor, (A) is a side view, (B) is a bottom view. It is a figure which shows the further another example of an antenna and a shield conductor, (A) is a side view, (B) is a bottom view. It is a figure which shows the further another example of an antenna and a shield conductor, (A) is a side view, (B) is a bottom view. It is a figure which shows the other example of a shield conductor, (A) is a side view, (B) is a bottom view. It is a figure which shows the further another example of a shield conductor, (A) is a side view, (B) is a bottom view. It is a schematic plan view showing an example in which a plurality of antennas are arranged in parallel.

  One embodiment of the plasma processing apparatus according to the present invention is shown in FIG. 2, and the antenna 30 and the shield conductor 60 are extracted and shown in FIG. However, in FIG. 3, the insulator 36 is omitted. In order to indicate the direction of the antenna 30 and the like, the X direction and the Y direction orthogonal to each other are shown in the drawing. In this example, the X direction and the Y direction are horizontal directions, and the X direction is the longitudinal direction of the antenna 30 (the same applies to 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 passing a high frequency current I _R from the high frequency power source 42 to the antenna 30, processed in the substrate 2 by using the plasma 50 Is an inductively coupled plasma processing apparatus.

  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 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.

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

  A holder 10 that holds the substrate 2 is provided in the vacuum container 4. 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.

  An 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 has a dimension in the X direction larger than a dimension in the Y direction, and the planar shape is planar. More specifically, the planar shape is rectangular in this embodiment, but is not limited thereto. The same applies to the planar shape of the antenna 30 of another example described 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.

The antenna 30 is supplied with high-frequency power from the high-frequency power source 42 via the matching circuit 44, whereby a high-frequency current I _R flows from one end 31 in the X direction of the antenna 30 to the other end 32 (because of high frequency). The direction of the high-frequency current I _R is reversed with time (the same applies hereinafter). 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 container 4 to ionize the gas 24 in the vicinity of the antenna 30 and generate a 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 other end 32 of the antenna 30 is grounded via the capacitor 45 in this embodiment, but may be directly grounded (the same applies to other examples described later).

  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 to this.

  In the examples shown in FIGS. 3 to 6, the matching circuit 44 is omitted for the sake of simplification. However, normally, like the example shown in FIG. Is provided with a matching circuit 44.

  A lower surface 33 which is a surface inside the vacuum vessel 4 (in other words, a surface on the plasma 50 side) of the antenna 30 is located in a vacuum atmosphere in the vacuum vessel 4, and an upper surface on the opposite side is located in the atmosphere. ing. A concave portion 34 and a convex portion 35 are formed on the lower surface 33, and concaves and convexes in the vertical direction (that is, a direction orthogonal to the XY plane; the same applies hereinafter) are provided. As shown in FIG. 3C, the unevenness extends over the entire length of the antenna 30 in the Y direction (width direction) (the same applies to other examples described later).

  Moreover, a larger number of convex portions 35 are arranged near both end portions than in the central portion of the antenna 30 in the X direction. More specifically, in the example shown in FIGS. 2 and 3, the central portion in the X direction of the antenna 30 is a concave portion 34, and a plurality of convex portions 35 are formed in steps on both sides thereof. That is, the plurality of convex portions 35 greatly protrude downward in a stepped manner as they approach both end portions of the antenna 30 in the X direction.

  In the vacuum vessel 4 and in the vicinity of the lower side of the antenna 30, it is electrically insulated from the antenna 30. Specifically, in this example, a space is provided between the antenna 30 and the antenna 30 and the plasma 50. A comb-shaped shield conductor 60 for shielding the electric field is provided.

  The shield conductor 60 has a plurality of linear conductors 62 in the X direction, each parallel to the Y direction (that is, orthogonal to the longitudinal direction X of the antenna 30), as can be seen with reference to FIG. ing. And it has the connection conductor 64 which electrically connects the one end part of the Y direction of the said some linear conductor 62 mutually in parallel. The other end in the Y direction of each linear conductor 62 is electrically open. The connection conductor 64 is electrically grounded so that the entire shield conductor 60 is grounded at one place. In this way, it is possible to prevent the circulating current from flowing in the shield conductor 60 by forming the shield conductor 60 in a closed loop.

  Each linear conductor 62 is preferably thin. The reason will be described later. Each linear conductor 62 is longer than the dimension in the width direction Y of the shield conductor 60, and the plurality of linear conductors 62 are provided over almost the entire area in the longitudinal direction X of the antenna 30, whereby the lower surface 33 of the antenna 30 is formed. It covers almost the whole area. 2 and 3, the plurality of linear conductors 62 are illustrated relatively coarsely for simplification of illustration, but it is preferable to arrange them densely as in the examples illustrated in FIGS. 7 and 8, for example. This is because the electric field shielding effect is enhanced. The same applies to other examples described later.

When high frequency current I _R to the antenna 30, by the skin effect, high frequency current I _R mainly flows through the surface portion of the antenna 30. Therefore, if the above-described unevenness is provided on the lower surface 33 of the antenna 30, the high-frequency current I _R flows along a path wavy in the vertical direction along the unevenness. As a result, it is possible to supply the high frequency power from a nearby more the projections 35 in the plasma 50, the high-frequency current flowing through the surface layer portion of the high frequency current I _R projections 35 than through the surface layer portion of the recess 34 in other words I _R has a stronger function of generating plasma 50 by being electromagnetically coupled with plasma 50 at a lower impedance. Therefore, if the convex portions 35 are arranged as described above, the opposite to the mountain shape, The plasma 50 can be generated more strongly in the vicinity of both end portions than in the central portion of the antenna 30 in the X direction. As a result, the peak-shaped plasma density distribution illustrated in FIG. 1 in the case of a simple flat antenna 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 X of the antenna 30 can be enhanced. For example, the uniformity of the film thickness distribution in the longitudinal direction X of the antenna 30 can be improved. Accordingly, it becomes easy to increase the size of the substrate 2 by making the antenna 30 longer.

On the other hand, if the antenna 30 is provided with irregularities as described above, the high-frequency current I _R flows along a corrugated path as described above, so that the effective path length of the high-frequency current I _R increases. The impedance (particularly inductance) of the antenna 30 is increased, and the potential difference between both ends of the antenna 30 is increased accordingly. An example of the potential of the antenna 30 is shown in FIG. If no countermeasure is taken, the potential of the antenna 30 is reflected in the plasma 50 via the electrostatic capacitance between the antenna 50 and the plasma potential also increases. Then, even if the uniformity of the plasma density distribution can be improved, the advantage of the inductively coupled plasma processing apparatus described above that the plasma potential can be lowered as compared with the capacitively coupled type is impaired. However, in this embodiment, since the electric field between the antenna 30 and the plasma 50 can be shielded by the shield conductor 60, the influence of the antenna potential on the plasma potential can be suppressed small, and the plasma potential can be suppressed low. .

  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, damage to the film formed on the substrate 2 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-described reason. Therefore, the antenna 30 can be made long to cope with the increase in size of the substrate 2. Become.

  Moreover, each linear conductor 62 constituting the comb-shaped shield conductor 60 is arranged in a direction orthogonal to the longitudinal direction X of the antenna 30 and is linear and has a small area. And the electrostatic capacitance between plasma 50 can be made small. Therefore, it can be suppressed that the shield conductor 60 becomes a kind of intermediate conductor and the effect of suppressing the plasma potential is lowered. From this point of view, it is preferable that each linear conductor 62 is not only arranged orthogonal to the antenna 30 but also thinner.

Furthermore, each linear conductor 62 constituting the shield conductor 60, in a direction perpendicular to the longitudinal direction X of the antenna 30, i.e. be arranged in a direction perpendicular to the high frequency current I _R flowing through the antenna 30, the high frequency current I _R Is not interlinked with the magnetic flux φ (some of which are shown in FIG. 3C), and the shield conductor 60 as a whole is comb-shaped and does not form a closed loop. It can suppress that a circulating current flows and a high frequency electric power loss generate | occur | produces. Therefore, high-frequency power can be efficiently used for plasma generation. If the shield conductor 60 has a lattice shape or a mesh shape, a circulating current flows in the shield conductor 60 and the high-frequency power loss increases. Thus, the effect of making the shield conductor 60 into a comb-shaped structure as described above is great.

  Further, since each linear conductor 62 constituting the shield conductor 60 is linear and has a small area, eddy currents flow in each linear conductor 62 and each linear conductor 62 is prevented from functioning as a high-frequency magnetic shield. can do. As a result, the electromagnetic energy from the antenna 30 can be efficiently used for plasma generation without being shielded by the shield conductor 60 as much as possible. Therefore, also from this viewpoint, the high-frequency power can be efficiently used for plasma generation. Also from this point of view, each linear conductor 62 is preferably thin.

  As described above, the plasma density distribution in the longitudinal direction X of the antenna 30 can be obtained by combining the concave and convex portions as described above on the lower surface 33 of the antenna 30 and using the comb-shaped shield conductor 60 as described above. The uniformity can be improved, the plasma potential can be kept low, and the high-frequency power radiated from the antenna 30 can be efficiently used for plasma generation even when the shield conductor 60 is provided.

  The number of convex portions 35 of the antenna 30 may be larger than the examples shown in FIGS. 2 and 3 and may have a larger number of steps than the examples. By doing so, it is possible to control the plasma density distribution in the longitudinal direction X of the antenna 30 more finely and further improve the uniformity of the plasma density distribution.

  As in the embodiment shown in FIG. 2, a shielding plate 46 that shields the surface inside the vacuum vessel 4 of the antenna 30, the shield conductor 60, and the like from the plasma 50 may be provided. 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. Instead of the antenna 30 shown in FIGS. 2 and 3, such a shielding plate 46 may be provided when an antenna 30 of another example described later is adopted.

  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.

  When the shielding plate 46 is provided, the surfaces of the antenna 30, the shield conductor 60, and the like are sputtered by charged particles (mainly ions) in the plasma 50, and metal contamination (metal contamination) occurs in the plasma 50 and the substrate 2. It is possible to prevent the occurrence of inconvenience.

  Even if the shielding plate 46 is provided, the shielding plate 46 is made of an insulating material and cannot prevent the potential of the antenna 30 from reaching the plasma 50. Therefore, it is effective to provide the shielding conductor 60.

  The recessed portion of the lower surface 33 of the antenna 30 (the space between the concave portion 34 and the convex portion 35 in the example shown in FIGS. 2 and 3 and the concave portion 34 in the example shown in FIGS. 4 to 6) is shown in FIG. As in the embodiment shown, it is preferably filled with an insulator 36. The same applies to the antenna 30 of another example described later.

  The material of the insulator 36 is, for example, resin, ceramics, etc., and is not limited to a specific one.

  If the depressed portion of the lower surface 33 of the antenna 30 is filled with the insulator 36, it is possible to prevent unnecessary plasma from being generated in the depressed portion. As a result, it is possible to prevent the occurrence of inconveniences such as an increase in the non-uniformity of the necessary plasma 50 and a reduction in the utilization efficiency of the high-frequency power.

  Next, some other examples of the antenna 30 will be described. In the apparatus shown in FIG. 2, the antenna 30 of the example shown in FIGS. 4 to 6 and 9 may be employed instead of the antenna 30 shown in FIGS.

  The antenna 30 shown in FIGS. 4 to 6 changes the pitch 35 in the longitudinal direction X of the antenna 30 by changing the pitch, width, number, etc. of the plurality of projections 35 constituting the irregularities of the lower surface 33 thereof. This is an example in which the central portion is relatively coarse and the both end portions are relatively densely arranged. More specifically, the central portion in the longitudinal direction X is a concave portion 34, and convex portions 35 are arranged on both sides thereof to change the pitch, width, number, etc. of the convex portions 35.

  That is, in the example shown in FIG. 4, a plurality of convex portions 35 are provided in the vicinity of both end portions in the longitudinal direction X of the antenna 30, and the intervals are reduced as the end portions are approached. In the example shown in FIG. 5, a plurality of convex portions 35 are provided in the vicinity of both end portions in the longitudinal direction X of the antenna 30, and the width of the convex portions 35 at both end portions is widened. In the example shown in FIG. 6, one wide convex portion 35 is provided in the vicinity of both end portions in the longitudinal direction X of the antenna 30. As in the example of FIG. 6, even when there is no convex portion at the center in the longitudinal direction X and there is one convex portion 35 near both ends (that is, when the convex portion 35 is 0 and 1), It can be said that the convex portions 35 are arranged roughly.

  Arranging the convex portions 35 roughly as described above and changing the height of the convex portions 35 as in the examples shown in FIGS. 2 and 3 may be used in combination.

  In the case of the antenna 30 shown in FIGS. 4 to 6, the same operational effects as those of the antenna 30 shown in FIGS. 2 and 3 can be obtained. That is, since the plasma 50 can be generated more strongly in the vicinity of both end portions than in the central portion in the longitudinal direction X of the antenna 30, the uniformity of the plasma density distribution in the longitudinal direction X of the antenna 30 can be improved. In addition, the above-described shield conductor 60 can suppress the plasma potential to be low, and can suppress the occurrence of high-frequency power loss in the shield conductor 60.

  The number of the convex portions 35 of the antenna 30 may be increased more than the example shown in FIG. By doing so, it is possible to control the plasma density distribution in the longitudinal direction X of the antenna 30 more finely and further improve the uniformity of the plasma density distribution.

  Some more specific examples of the comb-shaped shield conductor 60 will be described.

  As in the example shown in FIG. 7, each core wire of a flat cable (a cable in which a plurality of thin cables are arranged flatly) 70 attached to the lower surface of the insulating plate 68 is used as each of the linear conductors 62 and the shield conductor 60. May be configured. The insulating plate 68 and the shield conductor 60 may be provided with the insulating plate 68 on the upper side between the antenna 30 and the shielding plate 46 instead of the shield conductor 60 shown in FIG. The insulating plate 68 serves as a support for the shield conductor 60 (flat cable 70 or the like) and also serves to suppress the occurrence of discharge between the antenna 30 and the shield conductor 60. The same applies to the example shown in FIG.

  As in the example shown in FIG. 8, the shield conductor 60 may be configured by forming the linear conductor 62 and the connecting conductor 64 as a conductor pattern on the surface of the insulating sheet 72. Then, the insulating sheet 72 with the shield conductor 60 attached to the lower surface of the insulating plate 68 is replaced with the insulating plate 68 between the antenna 30 and the shielding plate 46 instead of the shield conductor 60 shown in FIG. It only has to be provided.

  As in the example shown in FIG. 9, 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 via variable impedances 52 respectively connected in series to each antenna 30. Alternatively, high frequency power may be supplied in parallel from a common high frequency power source 42.

  Each antenna 30 may have any configuration described with reference to FIGS.

  The shield conductor 60 has a size corresponding to the plurality of antennas 30. More specifically, the antenna 30 has a size that covers substantially the entire antenna 30.

  The variable impedance 52 may be a variable inductance as shown in FIG. 9, 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. 9, since a plurality of antennas 30 are arranged in parallel with each other and high-frequency power is supplied in parallel, plasma with a larger area can be generated. In addition, the uniformity of the plasma density distribution in the longitudinal direction X of each antenna 30 can be improved by the above action. 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. The uniformity can be improved. As a result, it is possible to generate a plasma having a larger area and good uniformity of the plasma density distribution.

2 Substrate 4 Vacuum container 24 Gas 30 Antenna 33 Bottom surface 34 Concave portion 35 Convex portion 42 High frequency power supply 50 Plasma 52 Variable impedance 60 Shield conductor 62 Linear conductor 64 Connecting conductor

Claims (4)

An inductively coupled plasma processing apparatus that generates a plasma by generating an induction electric field in a vacuum vessel by flowing a high-frequency current through an antenna, and processes the substrate using the plasma,
Assuming that the two directions orthogonal to each other are the X direction and the Y direction, the antenna has a dimension in the X direction larger than the dimension in the Y direction, and the high-frequency current flows from one end of the antenna to the other end in the X direction. Is to be swept away,
The lower surface, which is the surface inside the vacuum container of the antenna, is provided with irregularities in the vertical direction, and more convex portions are arranged near both ends than the central portion in the X direction of the antenna,
A comb-shaped shield conductor that is electrically insulated from the antenna and shields the electric field between the antenna and the plasma is provided below the antenna.
The shield conductor has a plurality of linear conductors each in the X direction parallel to the Y direction, and is an electrical conductor that electrically connects one end portions of the plurality of linear conductors in the Y direction in parallel. A plasma processing apparatus, characterized by having a connection conductor that is grounded.   The plasma processing apparatus according to claim 1, wherein the convex portion of the antenna protrudes greatly downward as approaching both end portions in the X direction of the antenna.   The plasma processing apparatus according to claim 1, wherein the convex portions of the antenna are relatively coarsely arranged at a central portion in the X direction of the antenna and relatively dense near both end portions. A plurality of the antennas, which are arranged in parallel in the Y direction;
Via a variable impedance connected in series to each of the antennas, the plurality of antennas are configured to supply high frequency power in parallel from a common high frequency power source,
The plasma processing apparatus according to claim 1, wherein the shield conductor has a size corresponding to the plurality of antennas.

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