JP2012133899A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of a large potential difference by limiting the increase in impedance, and consequently enable the generation of plasma with good uniformity even in a plane conductor increased in size.SOLUTION: The plasma processing device includes a plane conductor 30 having a holder-side surface 32 located in a vacuum chamber 4 and provided to face the substrate holding surface of a holder 10. The plane conductor 30 has at least one groove 40 along the direction of flow of RF current in the holder-side surface 32. The at least one groove 40 extends in a direction crossing the direction of flow of RF current, and has a depth larger than the skin thickness of RF current flowing in the plane conductor 30. The at least one groove 40 divides the holder-side surface 32 into more than one region. In each groove 40 of the plane conductor 30, a capacitor 42 is provided. The more than one region of the plane conductor 30, and the capacitor 42 are electrically connected in series with each other.

Description

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

  A planar conductor (flat RF antenna conductor) is attached to the opening of the vacuum vessel via an insulating frame, and a high-frequency power is supplied from a high-frequency power source between one end and the other end of the planar conductor, Patent Document 1 discloses an inductively coupled plasma processing apparatus that generates plasma by using an induced electric field and performs processing on a substrate using the plasma.

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

  In the above-described conventional plasma processing apparatus, when a planar conductor is made large in order to cope with a large substrate, the impedance (particularly inductance) of the planar conductor increases, thereby generating a large potential difference at both ends of the planar conductor. . As a result, under the influence of this large potential difference, plasma uniformity such as plasma density distribution, potential distribution, and electron temperature distribution is deteriorated, and the uniformity of substrate processing is also deteriorated.

  Therefore, the main object of the present invention is to suppress the increase of the impedance of the planar conductor even when the planar conductor is large, thereby suppressing the generation of a large potential difference in the planar conductor, thereby enabling the generation of a uniform plasma. Yes.

  A first plasma processing apparatus according to the present invention is a plasma processing apparatus that generates plasma by an induced electric field generated by flowing a high-frequency current through a conductor and performs processing on a substrate using the plasma, and is evacuated. And a vacuum vessel into which gas is introduced, a holder provided in the vacuum vessel for holding the substrate, and a surface on the holder side located in the vacuum vessel and facing the substrate holding surface of the holder A planar conductor provided, and a high-frequency power source that supplies high-frequency power to the planar conductor and causes the planar conductor to flow a high-frequency current, and the planar conductor has a surface on the holder side of the high-frequency current. A groove extending in a direction crossing the flow direction, the depth of which is larger than the skin thickness of the high-frequency current flowing in the planar conductor, the flow direction of the high-frequency current The holder-side surface is divided into a plurality of regions by the grooves, and capacitors are provided in the grooves of the planar conductor, respectively, and the regions of the planar conductor and the respective regions are provided. The capacitor is electrically connected to each other in series.

  In this plasma processing apparatus, the inductance of the surface of the planar conductor on the holder side is divided into a plurality of regions of inductance by the groove provided on the surface. The divided inductance is a circuit in which the capacitor is connected in series. The combined reactance constituting the impedance of the series circuit is simply obtained by subtracting the capacitive reactance 1 / ωC from the inductive reactance ωL, so that compared to the case where the groove and the capacitor are not provided in the planar conductor. The impedance of the surface of the planar conductor on the holder side can be reduced.

  As a result, even if the planar conductor is made large, it is possible to suppress an increase in impedance and to prevent a large potential difference from occurring in the planar conductor, thereby generating plasma with good uniformity. As a result, the uniformity of substrate processing can be improved.

  The space in each groove of the planar conductor may be filled with an insulator.

  Instead of providing the capacitors in the grooves of the planar conductor, capacitors may be formed in the grooves by filling the grooves with a dielectric.

  The inductance of each region of the planar conductor and the capacitance of each capacitor may satisfy a series resonance condition at the frequency of the high-frequency current when the plasma is generated.

  A plurality of the planar conductors having the groove and the capacitor are provided, and these planar conductors are arranged in series with each other. The planar conductors are electrically connected in series via connection capacitors, and the high-frequency conductors are connected to the planar conductors. You may comprise so that high frequency electric power may be supplied in series from a power supply.

  A plurality of the planar conductors having the groove and the capacitor are provided, and these planar conductors are arranged in parallel to each other, and the high-frequency power source is connected to the planar conductors via variable impedances connected in series to the planar conductors. The high frequency power may be supplied in parallel.

  A surface of the planar conductor on the holder side may be shielded from the plasma, and a shielding plate made of an insulating material may be provided.

  A second plasma processing apparatus according to the present invention is a plasma processing apparatus that generates plasma by an induced electric field generated by flowing a high-frequency current through a conductor and performs processing on a substrate using the plasma, and is evacuated. And a vacuum vessel into which gas is introduced, a holder provided in the vacuum vessel for holding the substrate, and a surface on the holder side located in the vacuum vessel and facing the substrate holding surface of the holder A planar conductor provided, and a high-frequency power source that supplies high-frequency power to the planar conductor and causes the planar conductor to flow a high-frequency current, and the planar conductor has a surface on the holder side of the high-frequency current. A plurality of recesses arranged along the flow direction and having one or more recess rows each having a depth greater than the skin thickness of the high-frequency current flowing through the planar conductor. The holder-side surface is divided into a plurality of rows of conductor surfaces by the recess rows, and the high-frequency power supply supplies high-frequency power in parallel to the plurality of rows of conductor surfaces of the planar conductor. Further, the planar conductor is a groove extending in a direction intersecting the flow direction of the high-frequency current on each of the conductor surfaces of each row, and the depth thereof is the high-frequency current flowing in the planar conductor. One or more grooves larger than the skin thickness are provided in the flow direction of the high-frequency current, and the conductor surface of each row is divided into a plurality of regions by the groove, and the grooves of the planar conductor are in the grooves. Each capacitor is provided in each of the regions, and each region in the conductor surface of each row and the capacitor in each groove are electrically connected in series with each other.

  According to the first aspect of the present invention, the inductance of the surface of the planar conductor on the holder side is divided into the inductance of a plurality of regions by the groove provided on the surface. A circuit in which a capacitor is connected in series to the divided inductance is obtained. The combined reactance constituting the impedance of the series circuit is simply obtained by subtracting the capacitive reactance 1 / ωC from the inductive reactance ωL, so that compared to the case where the groove and the capacitor are not provided in the planar conductor. The impedance of the surface of the planar conductor on the holder side can be reduced.

  As a result, even if the planar conductor is made large, it is possible to suppress an increase in impedance and to prevent a large potential difference from occurring in the planar conductor, thereby generating plasma with good uniformity. As a result, the uniformity of substrate processing can be improved.

  In addition, since the impedance of the surface of the planar conductor on the holder side, that is, the surface on the plasma generation side can be reduced, a high-frequency current can be preferentially passed through the surface as compared with the surface on the opposite side. As a result, high-frequency power can be efficiently used for plasma generation, and the utilization efficiency of the high-frequency power, and thus the substrate processing efficiency, can be increased.

  According to invention of Claim 2, there exists the following further effect. That is, since the space in each groove of the planar conductor is filled with an insulator, it is possible to prevent unnecessary plasma from being generated in each groove. As a result, it is possible to prevent the occurrence of inconveniences such as an increase in required plasma non-uniformity and a reduction in the utilization efficiency of high-frequency power.

  According to invention of Claim 3, there exists the following further effect. That is, instead of providing the capacitor in each groove of the planar conductor, the capacitor is formed in each groove by filling the dielectric in each groove, so that the configuration can be simplified. . Further, this dielectric can prevent unnecessary plasma from being generated in each groove.

  According to invention of Claim 4, there exists the following further effect. That is, since the inductance of each region of the planar conductor and the capacitance of each capacitor satisfy the series resonance condition at the frequency of the high-frequency current when plasma is generated, the impedance of the surface on the holder side of the planar conductor is further increased. Can be reduced. As a result, the effect described above for claim 1 can be further enhanced.

  According to invention of Claim 5, there exists the following further effect. That is, since a plurality of planar conductors having a groove and a capacitor are electrically connected in series via a connection capacitor, high frequency power is supplied in series from a high frequency power source to the plurality of planar conductors. A larger planar conductor can be realized by a combination of smaller planar conductors. As a result, it is possible to deal with larger substrate processing, making each planar conductor smaller and lighter, improving the workability of manufacturing, assembly, maintenance, etc., facilitating transportation, and loss during production. It leads to reduction.

  According to invention of Claim 6, there exists the following further effect. That is, since the high-frequency power is supplied in parallel from the high-frequency power source to the plurality of planar conductors via variable impedances connected in series to the plurality of planar conductors each having a groove and a capacitor. The effect similar to the effect mentioned above about 5 is show | played. Furthermore, since variable impedance is interposed in series and the variable impedance can improve the balance of the high-frequency current flowing through the plurality of planar conductors, the uniformity of the generated plasma can be improved.

  According to the seventh aspect of the present invention, the following further effect is obtained. That is, the shielding plate can suppress the charged particles in the plasma from being incident on the planar conductor or the like, so that it is possible to suppress an increase in the plasma potential due to the charged particles entering the planar conductor and It is possible to suppress the surface of a conductor or the like from being sputtered by charged particles and causing metal contamination (metal contamination) to the plasma and the substrate.

  According to the eighth aspect of the present invention, since the surface of the planar conductor on the holder side is divided into a plurality of rows of conductor surfaces by the recess rows, the flow of high-frequency current can be divided into a plurality of rows. As a result, the flow path of the high-frequency current on the surface of the planar conductor on the holder side becomes clear, and the flow of the high-frequency current can be easily adjusted. The uniformity can be improved, thereby improving the plasma uniformity. As a result, the uniformity of substrate processing can be improved.

  In addition, the gap between the conductor surfaces of each row can be reduced by dividing the planar conductor into a plurality of rows in a structural (mechanical) manner. The continuous region can be reduced to improve plasma uniformity. As a result, the uniformity of substrate processing can be improved.

  Furthermore, since the groove and the capacitor are provided on the conductor surface of each row and the impedance of the surface of the planar conductor on the holder side can be lowered, the same effect as the effect described above with respect to claim 1 is achieved.

  The inventions described in claims 9, 10, 11, 12, and 13 have the same configuration as the invention described in claims 2, 3, 4, 6, and 7, respectively. The effect similar to the effect mentioned above is produced.

It is sectional drawing which shows one Embodiment of the plasma processing apparatus which concerns on this invention. It is a figure which expands and shows the planar conductor periphery in FIG. 1, (A) is sectional drawing, (B) is a bottom view. FIG. 3 is an equivalent circuit diagram around the surface on the holder side of the planar conductor shown in FIG. 2. FIG. 4 is a diagram illustrating an example of a potential distribution when a series resonance condition is satisfied in the circuit of FIG. 3. It is sectional drawing which shows the other example of a plane conductor periphery. It is a bottom view which shows the further another example around a plane conductor. It is a bottom view which shows the further another example around a plane conductor. It is a bottom view which shows an example of the relationship between the planar conductor of FIG. 7, and a gas supply pipe.

  One embodiment of the plasma processing apparatus according to the present invention is shown in FIG. 1, and the periphery of the plane conductor is enlarged and shown in FIG.

  This apparatus is an inductively coupled plasma processing apparatus that generates plasma 60 by an induced electric field generated by flowing a high-frequency current from a high-frequency power source 70 to a planar conductor 30 and processes the substrate 2 using the plasma 60. .

  The substrate 2 is, for example, a flat panel display (FPD) substrate such as a liquid crystal display or an organic EL display, a flexible substrate for a flexible display, or the like, but is not limited thereto.

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

  This plasma processing apparatus is also called a plasma CVD apparatus when a film is formed by 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 path 25 and a gas supply pipe 26 provided on the ceiling surface 6 thereof. The gas supply pipe 26 has a plurality of gas ejection holes 28, which are provided upward. This is because the gas 24 is easily diffused in the vacuum vessel 4 to make the gas pressure near the substrate 2 uniform. In this embodiment, as shown in FIG. 2, the gas supply pipes 26 are arranged along the longitudinal direction of the planar conductor 30, one on each side sandwiching the planar conductor 30 in the lateral direction. In this way, the gas 24 can be supplied to the vicinity of the holder-side surface (in other words, the surface on the plasma generation side; hereinafter the same) 32 of the planar conductor 30 with good uniformity, and the gas supply pipe 26 is connected to the plasma. This can prevent the generation.

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 plasma CVD, the gas 24 is a gas obtained by diluting a source gas 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 60 are incident on the substrate 2 can be controlled to control the crystallinity of the film formed on the surface of the substrate 2.

  As in this embodiment, a heater 12 for heating the substrate 2 may be provided in the holder 10. A mask (also referred to as a shadow mask) 14 that prevents a film from being formed on the peripheral edge may be provided on the peripheral edge of the substrate 2. A partition plate 22 may be provided around the mask 14 for making the flow of the gas 24 uniform and preventing the plasma 60 from reaching the holding mechanism of the substrate 2 or the like.

  A planar conductor is provided such that the insulating frame 62 is interposed in the opening 7 of the ceiling surface 6 of the vacuum vessel 4 so that the surface 32 on the holder 10 side is located in the vacuum vessel 4 and faces the substrate holding surface of the holder 10. 30 is provided. Between these elements, a packing 63 for vacuum sealing is provided. The planar shape of the planar conductor 30 may be rectangular (rectangular) as in this embodiment, square, or the like.

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

  A high-frequency power is supplied from the high-frequency power source 70 via the matching circuit 68 between the feeding end 64 on one end side in the longitudinal direction of the planar conductor 30 and the terminal end 66 on the other end side. Will be washed away. The high-frequency current flow direction F is shown in FIG. The end 66 may be directly grounded as in this embodiment, or may be grounded via a capacitor. The same applies to other embodiments.

  By flowing a high-frequency current through the planar conductor 30, a high-frequency magnetic field is generated around the planar conductor 30, thereby generating an induced electric field in a direction opposite to the high-frequency current. Due to this induced electric field, electrons are accelerated in the vacuum chamber 4 to ionize the gas 24 in the vicinity of the planar conductor 30 and generate plasma 60 in the vicinity of the planar conductor 30. The plasma 60 diffuses to the vicinity of the substrate 2, and the above-described processing can be performed on the substrate 2 by the plasma 60.

  The frequency of the high-frequency power output from the high-frequency power source 70 is, for example, a general 13.56 MHz, but is not limited to this.

  Referring mainly to FIG. 2, the planar conductor 30 has a groove 40 extending on the holder-side surface 32 in a direction intersecting with the high-frequency current flow direction F (for example, a direction substantially perpendicular to the same). 1 or more in the flow direction F of the high-frequency current. This embodiment has a plurality (two in the illustrated example). As shown in FIG. 2B, each groove 40 is provided from one end to the other end of the planar conductor 30 in the short direction. By this groove 40, the holder-side surface 32 of the planar conductor 30 is divided into a plurality of (three in the illustrated example) regions 34.

  The depth D of each groove 40 is larger than the skin thickness δ of the high-frequency current flowing in the planar conductor 30.

  The skin thickness δ is expressed by the following equation. Here, f is the frequency of the high-frequency current, μ is the magnetic permeability of the planar conductor 30, and σ is the conductivity of the planar conductor 30.

[Equation 1]
δ = 1 / √ (πfμσ)

As a specific example, when the frequency f is 13.56 MHz and the planar conductor 30 is pure copper, the permeability μ is 4π × 10 ⁻⁷ N / A ² and the conductivity σ is 59.6 × 10 ⁶ / Ωm. Therefore, the skin thickness δ is about 17.7 μm. When the planar conductor 30 is aluminum, the permeability μ is 4π × 10 ⁻⁷ N / A ² and the conductivity σ is 37.7 × 10 ⁶ / Ωm, so the skin thickness δ is about 22.2 μm. .

  Further, capacitors 42 are provided in the grooves 40, respectively, and the regions 34 of the planar conductor 30 and the capacitors 42 are alternately electrically connected in series. The number of capacitors 42 provided in each groove 40 will be described later. Both ends of each capacitor 42 are connected to both sides of each groove 40 by connecting conductors 44.

  Since the skin thickness δ is very small as described above, the high-frequency current flows only on the surface of the planar conductor 30. Therefore, if the grooves 40 having a depth D larger than the skin thickness δ are provided, the impedance of each groove 40 becomes very large, and the inductance of the surface 32 on the holder side of the planar conductor 30 is in a plurality of regions. Divided into 34 inductances. The capacitor 42 is connected in series to the divided inductance. An equivalent circuit of this series circuit is shown in FIG.

  In FIG. 3, the inductance of each region 34 is L, the resistance is R, and the capacitance of each capacitor 42 is C. The inductance L and resistance R are determined by the structure of the planar conductor 30 and can be set to substantially the same value in each region 34. The same value can be selected for the capacitance C of each capacitor 42.

  The combined reactance constituting the impedance of the series circuit is simply obtained by subtracting the capacitive reactance 1 / ωC from the inductive reactance ωL, so that the groove 40 and the capacitor 42 are not provided in the planar conductor 30. In comparison with this, the impedance of the surface 32 on the holder side of the planar conductor 30 can be reduced. ω is the angular frequency of the high-frequency current.

  More specifically, the impedance Z of the series circuit is expressed by the following equation. Since this impedance Z includes ωL−1 / ωC, the reactance can be reduced, and therefore the impedance Z can be lowered.

[Equation 2]
Z = 3 (R + jωL) +2 (1 / jωC)
= 3R + 2j (ωL−1 / ωC) + jωL

  A capacitor may be provided in series between the terminal 66 of the planar conductor 30 and the ground. When the capacitance of the capacitor is C, the impedance Z in that case is expressed by the following equation. Also in this case, since the impedance Z includes ωL−1 / ωC, the reactance can be reduced, and thus the impedance Z can be lowered.

[Equation 3]
Z = 3R + 3j (ωL-1 / ωC)

  In any case, since the impedance of the surface 32 on the holder side of the planar conductor 30 can be reduced as described above, the following effects are produced.

  (A) Even if the size of the planar conductor 30 is increased, it is possible to suppress an increase in impedance and to prevent a large potential difference from occurring in the planar conductor, thereby generating a plasma 60 with good uniformity. As a result, the processing uniformity of the substrate 2 can be improved.

  (B) Moreover, since the impedance of the surface 32 on the holder side of the flat conductor 30, that is, the surface on the plasma generation side can be reduced, a high-frequency current is preferentially applied to the surface 32 compared to the opposite surface. It can flow. As a result, a high-frequency current can be preferentially flowed in the immediate vicinity of the plasma 60, so that high-frequency power can be efficiently used for plasma generation, and the utilization efficiency of the high-frequency power and, consequently, the processing efficiency of the substrate 2 can be increased. it can.

  The inductance L of each region 34 of the planar conductor 30 and the capacitance C of each capacitor 42 provided in each groove 40 (the combination thereof when a plurality of capacitors are provided in parallel) are generated when the plasma 60 is generated. It is preferable to satisfy the series resonance condition expressed by the following equation at the frequency (hereinafter, angular frequency ω).

[Equation 4]
ωL = 1 / ωC

  Here, “when the plasma 60 is generated” is specified because the inductance L when the plasma is generated depends on the density of the plasma 60, but is about 60% to 70% at the maximum when the plasma is not generated. This is because it is known from experience that it is preferable to satisfy the above-described resonance condition. Therefore, it is sufficient to design in consideration of this decrease.

  When the above resonance condition is satisfied, the above formulas 2 and 3 become the following formulas 5 and 6, respectively, so that the impedance of the surface 32 on the holder side of the planar conductor 30 can be further reduced. As a result, the effects (a) and (b) can be further enhanced.

[Equation 5]
Z = 3R + jωL

[Equation 6]
Z = 3R

In the circuit of FIG. 3, an example of the potential distribution when the series resonance condition of Equation 4 is satisfied is shown by a solid line A in FIG. The points a to d in FIG. 4 correspond to the points a to d in FIG. Each slope S ₁ is a potential increase due to inductive reactance ωL, and each slope S ₂ is a potential drop due to capacitive reactance 1 / ωC.

  A two-dot chain line B in FIG. 4 is a potential distribution in the case of a conventional planar conductor that does not have the one corresponding to the groove 40 and the capacitor 42.

  As can be seen from FIG. 4, in the case of the planar conductor 30 having the groove 40 and the capacitor 42, the potential difference between the respective portions on the holder-side surface 32 can be kept small. Therefore, also from this viewpoint, it is possible to generate the plasma 60 with better uniformity, and further improve the uniformity of the substrate processing.

  Although it is preferable that the series resonance condition shown in Formula 4 is satisfied, even if the resonance condition is not completely satisfied, for example, even in a state in the vicinity of the resonance condition, the potential difference of each part of the planar conductor 30 is reduced. The effect of suppressing can be produced. In this case, for example, the potentials at points b and d in FIG. 4 are somewhat shifted to the positive side or the negative side, and the potentials of other portions are also shifted accordingly. Nevertheless, as compared with the case of the conventional planar conductor indicated by the two-dot chain line B, the potential difference between the respective parts can be suppressed to be small.

  One capacitor 42 may be provided in each of the grooves 40, or a plurality (two in the illustrated example) may be provided in parallel as in this embodiment. The same applies to other embodiments described later. When a plurality of capacitors 42 are provided in parallel, a high-frequency current can be distributed and flowed through the plurality of capacitors 42, so that the high-frequency current can flow more uniformly in the plane of the planar conductor 30. As a result, the uniformity of the plasma 60 can be improved. Further, when a plurality of capacitors 42 are provided in parallel, it is easy to increase the capacitance.

  The space in each groove 40 (the space including the periphery of the capacitor 42 and the connection conductor 44) is preferably filled with an insulator 46 as in this embodiment. The same applies to other embodiments described later. In FIG. 2B and FIGS. 6 to 8, the insulator 46 covering the capacitor 42 is not shown for easy understanding of the arrangement of the capacitor 42.

  The material of the insulator 46 is, for example, resin, ceramics, etc., and is not limited to a specific one.

  If the space in each groove 40 is filled with the insulator 46 as described above, unnecessary plasma can be prevented from being generated in each groove 40. As a result, it is possible to prevent the occurrence of inconveniences such as an increase in the non-uniformity of the necessary plasma 60 and a decrease in the utilization efficiency of the high-frequency power. The same applies to other embodiments described later.

  Instead of providing the capacitors 42 in the grooves 40 of the planar conductor 30, capacitors may be formed in the grooves 40 by filling the grooves 40 with a dielectric. The same applies to other embodiments described later. Since the side walls on both sides of each groove 40 in the high-frequency current flow direction F serve as electrodes and the dielectric is sandwiched therebetween, a capacitor corresponding to the capacitor 42 can be formed in each groove 40. it can. The equivalent circuit in this case is the same as that shown in FIG.

  The dielectric is preferably a high dielectric constant material such as barium titanate or magnesium titanate. This is because a larger capacitance can be realized. The capacitance of the capacitor to be formed can be adjusted by the dielectric constant of the dielectric, the width, length, depth D, etc. of each groove 40. It is also possible to satisfy the series resonance condition described above.

  When capacitors are formed by filling dielectrics in the respective grooves 40 as described above, the bulk capacitor 42 and the connection conductor 44 therefor are not required, so that the configuration can be simplified. Furthermore, this dielectric can provide the same effects as the case where the insulator 46 is filled. That is, it is possible to prevent unnecessary plasma from being generated in each groove 40.

  As in this embodiment, the surface 32 on the holder side of the planar conductor 30 is shielded from the plasma 60, and a shielding plate 72 made of an insulating material may be provided. The same applies to other embodiments described later. The shielding plate 72 may be directly attached to the inlet portion of the opening 7 of the vacuum vessel 4 (specifically, the ceiling surface 6 thereof), or may be attached using a frame-like pressing plate 74 as in this embodiment. Also good.

  The material of the shielding plate 72 is, for example, quartz, alumina, silicon carbide, silicon or the like. If it is difficult to reduce oxygen by the hydrogen plasma and release oxygen from the shielding plate 72, a non-oxide material such as silicon or silicon carbide may be used. For example, it is easy to use a silicon plate.

  As is well known, in the case of a structure in which the conductor and the high-frequency plasma are close to each other, electrons are lighter and much more incident on the conductor than ions in the plasma, so that the plasma potential rises to the positive side of the conductor. On the other hand, if the shielding plate 72 as described above is provided, the shielding plate 72 can prevent the charged particles in the plasma 60 from entering the planar conductor 30 or the like. The rise in plasma potential due to the incidence of charged particles (mainly electrons) can be suppressed, and the surface of the planar conductor 30 or the like is sputtered by charged particles (mainly ions) to contaminate the plasma 60 and the substrate 2 with metal contamination. The occurrence of (metal contamination) can be suppressed.

  Next, in another embodiment of the plasma processing apparatus according to the present invention, parts that are the same as or equivalent to those in the above-described embodiment are denoted by the same reference numerals, and differences from the embodiment described above are mainly used. Explained.

  As in the embodiment shown in FIG. 5, a plurality (two in the illustrated example) of planar conductors 30 having the above-described grooves 40 and capacitors 42 are arranged in series with each other (that is, the flow of high-frequency current in the plurality of planar conductors 30). The direction planes F (see FIG. 2) are arranged in series with each other), and the plurality of planar conductors 30 are electrically connected in series with each other via a connection capacitor 76 outside (also outside the vacuum vessel). The high-frequency power may be supplied in series from the high-frequency power source 70 to the plurality of planar conductors 30 via the matching circuit 68. An insulating frame 62 and a packing 63 similar to those described above are provided at locations where the plurality of planar conductors 30 are adjacent to each other.

  In this way, a substantially larger planar conductor can be realized by a combination of smaller planar conductors 30 than that. As a result, it is possible to cope with processing of larger substrates, and by making each planar conductor 30 smaller and lighter, workability such as manufacture, assembly, and maintenance is improved, transportation is facilitated, and production is facilitated. It also leads to reduced damage.

  As in the case of the embodiment shown in FIGS. 1 and 2, each planar conductor 30 is formed by forming a capacitor in each groove 40 by filling a dielectric in each groove 40 instead of providing the capacitor 42. But it ’s okay. The same applies to other embodiments described later.

  The number of connection capacitors 76 that connect between adjacent planar conductors 30 may be one, or a plurality of connection capacitors 76 may be provided in parallel in the width direction of the planar conductors (short direction, front and back direction in FIG. 5). When a plurality of parallel conductors are provided in parallel, the high-frequency current can be distributed and supplied to the plurality of connection capacitors 76, so that the high-frequency current can be supplied more uniformly in the plane of each planar conductor 30. As a result, the uniformity of the plasma 60 can be improved.

  As in the embodiment shown in FIG. 6, a plurality (two in the illustrated example) of planar conductors 30 having the above-described grooves 40 and capacitors 42 are arranged in parallel with each other (that is, the flow of high-frequency current in the plurality of planar conductors 30). The high-frequency power may be supplied in parallel to the plurality of planar conductors 30 from the high-frequency power source 70 via the matching circuit 68).

  In this way, the same effect as that of the embodiment shown in FIG. 5 can be obtained. That is, a substantially larger planar conductor can be realized by a combination of smaller planar conductors 30. As a result, it is possible to cope with processing of larger substrates, and by making each planar conductor 30 smaller and lighter, workability such as manufacture, assembly, and maintenance is improved, transportation is facilitated, and production is facilitated. It also leads to reduced damage.

  In the above case, a variable impedance 78 is connected in series to one end side of one or more plane conductors 30, preferably to one end side of all the plane conductors 30, and a plurality of plane conductors 30 are connected via the variable impedance 78. It is preferable to supply a high-frequency current from the high-frequency power source 70 in parallel. FIG. 6 shows an example of this case.

  If the variable impedance 78 is interposed in series as described above, the balance of the high-frequency currents flowing through the plurality of planar conductors 30 can be improved by the variable impedance 78, so that the uniformity of the generated plasma 60 is improved. be able to.

  The variable impedance 78 may be a variable inductance as shown in FIG. 6, 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, so that it is possible to suppress the current of the planar conductor 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 lowered (refer to the above-described equations 2 and 3 and the description thereof). It is possible to increase the current of the planar conductor 30 that is difficult to flow.

  As in the embodiment shown in FIG. 7, the planar conductor 30 has one or more recess rows 50 including a plurality of recesses 48 arranged along the flow direction F of the high-frequency current on the holder-side surface 32 (see FIG. 7). The holder side surface 32 may be divided into a plurality of rows (three rows in the illustrated example) of the conductor surfaces 52 by the recess rows 50. The plurality of recesses 48 are discontinuous separated from each other.

  High frequency power is supplied in parallel to the plurality of rows of conductor surfaces 52 from a high frequency power source 70 via a matching circuit 68.

  Further, the planar conductor 30 has at least one groove 40 extending in the direction crossing the high-frequency current flow direction F in each row of the conductor surfaces 52 in the high-frequency current flow direction F (two in the illustrated example). The conductor surface 52 of each row is divided into a plurality of (three in the illustrated example) regions 34 by the grooves 40.

  Further, capacitors 42 are provided in the respective grooves 40, and the regions 34 and the capacitors 42 in the conductor surfaces 52 of the respective columns are alternately electrically connected in series.

  The depth of each groove 40, the capacitor 42, the connecting conductor 44, the insulator 46, etc. are the same as those described in the embodiment shown in FIGS. .

  The depth of each recess 48 is larger than the aforementioned skin thickness δ of the high-frequency current flowing through the conductor 30. The reason for this is the same as described above for the depth D of the groove 40. That is, when the plurality of recesses 48 having such depths are arranged in a discontinuous manner, the impedance of each recess array 50 with respect to the high-frequency current becomes very large. Therefore, the high-frequency current on the holder-side surface 32 of the planar conductor 30 The flow can be divided into multiple rows, i.e., multiple rows of conductor surfaces 52. As a result, the flow path of the high-frequency current on the holder-side surface 32 of the planar conductor 30 becomes clear, and the flow of the high-frequency current can be easily adjusted. The uniformity of the flowing high frequency current can be improved, and thereby the uniformity of the plasma 60 (see FIG. 1) can be improved. As a result, the uniformity of substrate processing can be improved.

  Moreover, the gap between the conductor surfaces 52 in each row can be reduced by dividing the planar conductor 30 into a plurality of rows in a structural (mechanical) manner, so that the gap between the conductor surfaces 52 in each row can be reduced. The uniformity of the plasma 60 can be improved by reducing the current discontinuous region. As a result, the uniformity of substrate processing can be improved.

  Furthermore, since the groove 40 and the capacitor 42 are provided in the conductor surface 52 of each row and the impedance of the surface 32 on the holder side of the planar conductor 30 can be lowered, the embodiment shown in FIGS. This produces the same effect as the above effect.

  By the way, instead of the recess row 50 as described above, even if a slit-like groove connecting the plurality of recesses 48 is provided along the flow direction F of the high-frequency current, the flow of the high-frequency current is divided into a plurality of rows. It is not possible. This is because, in the case of such a slit-shaped groove, the bottom surface is continuous along the flow direction F of the high-frequency current, and the high-frequency current flows along the bottom surface.

  As in the case of the groove 40, the space in each recess 48 is preferably filled with an insulator such as resin or ceramics. By doing so, it is possible to prevent unnecessary plasma from being generated in each recess 48 as in the case of the groove 40. As a result, it is possible to prevent the occurrence of inconveniences such as an increase in the non-uniformity of the necessary plasma 60 and a decrease in the utilization efficiency of the high-frequency power.

  Also in the embodiment shown in FIG. 7, (a) the inductance of each region 34 in the conductor surface 52 of each row of the planar conductors 30 and the capacitance of each capacitor 42 are the same as those of the high-frequency current when the plasma 60 is generated. It is preferable to satisfy the series resonance condition at the frequency. (B) Instead of providing the capacitors 42 in the grooves 40 of the planar conductor 30, the grooves 40 are filled with a dielectric material in the grooves 40. (C) a plurality of rows of conductor surfaces 52 are connected to one end side of the conductor surface 52 of each row of planar conductors 30 via a variable impedance 78 in series. It is also possible to supply high-frequency power from 70 in parallel. (D) It is intended to shield the holder-side surface 32 of the planar conductor 30 from the plasma 60 and be an insulator. The shielding plate 72 (see FIG. 1 and FIG. 2) may be provided, and the operation and effect when doing so are the same as those of the embodiment shown in FIG. 1 and FIG. Therefore, the description will be referred to, and redundant description will be omitted here.

  A plurality of planar conductors 30 as shown in FIG. 7 are arranged in series with each other, and the conductor surfaces 52 of each row are electrically connected in series with each other via a connection capacitor 76 as shown in FIG. good. By doing so, it becomes easy to generate a plasma 60 having a larger area and cope with a larger substrate. As in the case of the embodiment of FIG. 5, the number of connection capacitors 76 that connect the conductor surfaces 52 of each row may be one, or a plurality of them may be provided in parallel.

  For example, as shown in FIG. 8, the gas supply pipe 26 in the case of the planar conductor 30 shown in FIG. 7 includes the gas supply pipe 26 along the longitudinal direction of the planar conductor 30 on both sides sandwiching the planar conductor 30 in the short direction. One may be provided one by one and one at a position corresponding to each recess row 50. In this way, the gas 24 can be supplied to the vicinity of the holder-side surface 32 of the planar conductor 30 with good uniformity, and the gas supply pipe 26 is less likely to interfere with plasma generation.

2 Substrate 4 Vacuum vessel 10 Holder 24 Gas 30 Planar conductor 32 Holder side surface 34 Region 40 Groove 42 Capacitor 46 Insulator 48 Recess 50 Recess array 52 Conductor surface 60 Plasma 70 High frequency power supply 72 Shield plate 76 Connection capacitor 78 Variable impedance

Claims (13)

A plasma processing apparatus that generates plasma by an induced electric field generated by flowing a high-frequency current through a conductor and performs processing on a substrate using the plasma,
A vacuum vessel that is evacuated and into which gas is introduced;
A holder provided in the vacuum vessel and holding a substrate;
A planar conductor provided so that a surface on the holder side is located in the vacuum container and faces a substrate holding surface of the holder;
A high-frequency power supply for supplying high-frequency power to the planar conductor and causing a high-frequency current to flow through the planar conductor;
The planar conductor is a groove extending in a direction intersecting the flow direction of the high-frequency current on the surface on the holder side, and the depth thereof is larger than the skin thickness of the high-frequency current flowing in the planar conductor. Having one or more large grooves in the flow direction of the high-frequency current, and the surface on the holder side is divided into a plurality of regions by the grooves;
A plasma processing apparatus, wherein a capacitor is provided in each groove of the planar conductor, and the regions of the planar conductor and the capacitors are electrically connected in series with each other.   The plasma processing apparatus according to claim 1, wherein a space in each groove of the planar conductor is filled with an insulator.   The plasma processing apparatus according to claim 1, wherein a capacitor is formed in each of the grooves by filling a dielectric in each of the grooves instead of providing the capacitor in each of the grooves of the planar conductor.   4. The plasma according to claim 1, wherein the inductance of each region of the planar conductor and the capacitance of each capacitor satisfy a series resonance condition at the frequency of the high-frequency current when the plasma is generated. Processing equipment. A plurality of the planar conductors having the grooves and capacitors, and these are arranged in series with each other;
5. Each of the planar conductors is electrically connected in series via a connection capacitor, and high frequency power is supplied in series from the high frequency power source to the plurality of planar conductors. The plasma processing apparatus as described. A plurality of the planar conductors having the grooves and capacitors, and these are arranged in parallel with each other;
The high-frequency power is supplied in parallel from the high-frequency power source to the plurality of planar conductors via variable impedances connected in series to the planar conductors, respectively. Plasma processing equipment.   The plasma processing apparatus according to any one of claims 1 to 6, further comprising a shielding plate made of an insulator for shielding the surface of the planar conductor on the holder side from the plasma. A plasma processing apparatus that generates plasma by an induced electric field generated by flowing a high-frequency current through a conductor and performs processing on a substrate using the plasma,
A vacuum vessel that is evacuated and into which gas is introduced;
A holder provided in the vacuum vessel and holding a substrate;
A planar conductor provided so that a surface on the holder side is located in the vacuum container and faces a substrate holding surface of the holder;
A high-frequency power supply for supplying high-frequency power to the planar conductor and causing a high-frequency current to flow through the planar conductor;
The planar conductor is a plurality of recesses arranged along the flow direction of the high-frequency current on the surface on the holder side, the depth of which is greater than the skin thickness of the high-frequency current flowing in the planar conductor Having one or more recess rows made of large recesses, and the holder-side surface is divided into a plurality of conductor surfaces by the recess rows;
The high-frequency power supply supplies high-frequency power in parallel to the conductor surfaces of the plurality of rows of the planar conductors,
Further, the planar conductor is a groove extending in a direction intersecting the flow direction of the high-frequency current on each of the conductor surfaces of each row, and the depth thereof is the skin of the high-frequency current flowing in the planar conductor. Having at least one groove larger than the thickness in the flow direction of the high-frequency current, and the conductor surface of each row is divided into a plurality of regions by the groove,
And each capacitor | condenser is provided in each said groove | channel of the said planar conductor, Each said area | region in the conductor surface of each said row | line and the said capacitor | condenser in each said groove | channel are mutually electrically connected in series, Plasma processing equipment.   The plasma processing apparatus according to claim 8, wherein a space in each concave portion and a space in each groove of the planar conductor is filled with an insulator.   9. The plasma processing apparatus according to claim 8, wherein a capacitor is formed in each groove by filling a dielectric in each groove instead of providing the capacitor in each groove of the planar conductor.   9. The inductance of each region and the capacitance of each capacitor on the conductor surface of each row of the planar conductor satisfy a series resonance condition at the frequency of the high-frequency current when the plasma is generated. The plasma processing apparatus of 9 or 10.   The high-frequency power is supplied in parallel from the high-frequency power source to the conductor surfaces of the plurality of rows via variable impedances connected in series to the conductor surfaces of the rows of the planar conductors, respectively. , 9, 10 or 11.   The plasma processing apparatus according to any one of claims 8 to 12, further comprising a shielding plate made of an insulator for shielding the surface of the planar conductor on the holder side from the plasma.

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