JP2017033788A - Plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a decrease in plasma density in both end regions of an antenna in a longitudinal direction, more specifically in the vicinity of both end portions of a substrate in the longitudinal direction.SOLUTION: A plasma processing apparatus is provided with auxiliary electrodes 70 to be apart from an antenna 20 with gaps D, Dtherebetween, respectively, at positions corresponding to the vicinity of both end portions of a substrate 10 in a longitudinal direction of the antenna 20 in a vacuum container 2, with respect to the antenna 20. Each of the auxiliary electrodes 70 is electrically grounded.SELECTED DRAWING: Figure 1

Description

  The present invention is directed to plasma processing in which an induction electric field is generated in a vacuum vessel by flowing a high-frequency current through an antenna disposed in the vacuum vessel to generate inductively coupled plasma, and the substrate is processed using the plasma. Relates to the device. The treatment applied to the substrate is, for example, film formation by plasma CVD or the like, etching, ashing, sputtering, or the like.

  2. Description of the Related Art Conventionally, a plasma processing apparatus has been proposed in which a high-frequency current is passed through an antenna and inductively coupled plasma (abbreviated as ICP) is generated in a vacuum vessel by an induced electric field generated thereby.

  For example, Patent Document 1 proposes a plasma processing apparatus that includes a substantially straight antenna disposed in a vacuum vessel. More specifically, a plasma processing apparatus having a structure in which a plurality of linear antennas each having an insulating pipe and an antenna body disposed therein are arranged in parallel in a direction along the surface of the substrate in the metal vacuum vessel. Has been proposed. The antenna thus arranged in the vacuum container is also called an internal antenna.

  Although the antenna body may be made of a metal pipe, in Patent Document 1, the antenna body has a structure in which (a) a plurality of metal pipes are connected in series with a hollow insulator interposed between adjacent metal pipes. (B) and a capacitor provided in the hollow insulator portion, and the metal pipes on both sides of the hollow insulator and the capacitor are electrically connected in series.

Japanese Patent No. 5733460

  When plasma is generated in a vacuum vessel using the above antenna (internal antenna), the plasma density in both end regions in the longitudinal direction of the antenna is usually smaller than the plasma density in the central region of the antenna. This is because, in short, both end regions in the longitudinal direction of the antenna have a larger loss due to plasma diffusion toward the wall surface of the surrounding vacuum vessel.

  As a result, for example, when a film is formed on the substrate using the plasma, the film thickness is reduced near the edge of the substrate. In addition, when the film on the substrate is etched using the plasma, a state where the etching cannot be sufficiently performed near the edge of the substrate occurs.

  Even if the plasma density distribution is nonuniform as described above, there is a method of using only a range with good uniformity of the plasma density distribution. However, by doing so, the usable range becomes narrow and can be processed. Problems such as a reduction in the size of the substrate occur. In order to avoid this, if the length of the antenna is deliberately increased to widen the range with good uniformity, problems such as an increase in the size of the apparatus arise.

  The above-described problems exist not only when the antenna body includes the metal pipe, the hollow insulator, and the capacitor described above, but also when the antenna body is made of a metal pipe.

  Therefore, the present invention improves the above points and suppresses a decrease in plasma density in both end regions in the longitudinal direction of the antenna, more specifically in the vicinity of both end portions of the substrate in the same longitudinal direction. The main object is to provide a plasma processing apparatus capable of performing the above.

  In the plasma processing apparatus according to the present invention, an inductive electric field is generated in the vacuum vessel by flowing a high-frequency current through a substantially straight antenna disposed in the vacuum vessel to generate inductively coupled plasma. A plasma processing apparatus for processing a substrate using plasma, wherein the antenna and the antenna are located at positions corresponding to the vicinity of both ends of the substrate in the longitudinal direction of the antenna with respect to the antenna. Auxiliary electrodes that are electrically grounded are provided with a gap between them.

  According to this plasma processing apparatus, inductively coupled plasma is generated around the antenna by passing a high-frequency current through the antenna. In addition, when a high-frequency current flows through the antenna, the potential of the antenna rises, and a high-frequency electric field is generated between the antenna and each auxiliary electrode of the ground potential. The high-frequency electric field can increase the plasma density. As a result, a decrease in plasma density in the vicinity of both ends of the substrate in the longitudinal direction of the antenna can be suppressed.

  The antenna has an insulating pipe and a hollow antenna body that is disposed therein and into which cooling water flows, and the antenna body includes (a) a plurality of metal pipes and adjacent metals. It has a structure in which a hollow insulator is interposed between pipes and connected in series, and (b) includes a capacitor electrically connected in series with the metal pipe on both sides of the hollow insulator. It may be adopted.

  The terminal portion of the antenna may be grounded via a coil.

  Each auxiliary electrode may be one in which cooling water flows.

  Each auxiliary electrode may be covered with an insulator.

  The surface of the insulator may be coated with a film formed on the substrate or the same kind of substance as its component.

  Other modifications may be adopted.

  According to the first aspect of the present invention, inductively coupled plasma is generated around the antenna by applying a high-frequency current to the antenna. In addition, when a high-frequency current flows through the antenna, the potential of the antenna rises, and a high-frequency electric field is generated between the antenna and each auxiliary electrode of the ground potential. The high-frequency electric field can increase the plasma density. As a result, it is possible to improve the uniformity of the plasma density distribution in the longitudinal direction of the antenna by suppressing a decrease in the plasma density in the vicinity of both ends of the substrate in the longitudinal direction of the antenna.

  According to invention of Claim 2, there exists the following further effect. That is, the antenna body has a structure in which a plurality of metal pipes are connected in series with a hollow insulator interposed between adjacent metal pipes, and is electrically connected in series with the metal pipes on both sides of the hollow insulator. Since the capacitor is provided, the impedance of the antenna can be reduced, and thereby the potential difference between both ends of the antenna can be reduced. As a result, it becomes easy to balance the plasma density increasing action by the left and right auxiliary electrodes.

  According to invention of Claim 3, there exists the following further effect. That is, since the terminal end of the antenna is grounded via the coil, the potential of the entire antenna can be raised by the voltage generated at both ends of the coil. As a result, the electric field between the antenna and each auxiliary electrode is strengthened, and it becomes easy to strengthen the plasma density increasing action by each auxiliary electrode.

  According to invention of Claim 4, there exists the following further effect. That is, each auxiliary electrode can be cooled with cooling water to suppress the temperature rise of each auxiliary electrode, so that the room for selecting the material of each auxiliary electrode is widened.

  According to invention of Claim 5, there exists the following further effect. That is, since each auxiliary electrode is covered with an insulator, it is possible to prevent the metal constituting each auxiliary electrode from being mixed as an impurity into the plasma by sputtering each auxiliary electrode with plasma. That is, the occurrence of metal contamination (metal contamination) can be suppressed.

  According to invention of Claim 6, there exists the following further effect. That is, since the surface of the insulator is coated with a film formed on the substrate or the same kind of material as its component, even if the surface of the insulator is sputtered with plasma, other than the material constituting the film The impurities can be prevented from being mixed into the film. Therefore, a high-quality film with few impurities can be formed.

  According to the seventh aspect of the present invention, the following further effect is obtained. That is, since the surface of the insulator is coated with a film formed on the substrate or the same kind of material as the component, the material that forms the film even if the surface of the insulator is etched with plasma. Since the same kind of substance is only etched out as a gas, the film can be prevented from being contaminated with impurities. Therefore, etching with less contamination by impurities can be performed.

  The invention according to claim 8 has the following further effect. That is, a plurality of antennas are arranged in parallel in the direction along the surface of the substrate, and the auxiliary electrode is provided for each antenna, so that plasma with good uniformity can be generated in a wider area. Therefore, it is possible to deal with a larger substrate processing.

It is a schematic longitudinal cross-sectional view which shows one Embodiment of the plasma processing apparatus which concerns on this invention. It is a schematic longitudinal cross-sectional view which shows an example of an auxiliary electrode. It is a schematic perspective view which shows the other example of an auxiliary electrode, and the near side is cut | disconnected. It is a schematic perspective view which shows the other example of an auxiliary electrode, and the near side is cut | disconnected. It is a schematic sectional drawing which expands and shows an example of the circumference | surroundings of the capacitor | condenser in FIG. It is a schematic sectional drawing which expands and shows the other example of the circumference | surroundings of the capacitor | condenser in FIG. It is a schematic cross-sectional view showing an embodiment of a plasma processing apparatus having a plurality of antennas. It is the schematic which shows an example of the experimental result which measured the edge part voltage (peak peak value of the high frequency voltage) of the antenna about the case where a termination part coil is present.

  FIG. 1 shows an embodiment of a plasma processing apparatus according to the present invention. In order to facilitate understanding of the directions, the X direction, the Y direction, and the Z direction that are orthogonal to each other at one point are illustrated in each drawing. For example, the X direction and the Y direction are horizontal directions, and the Z direction is a vertical direction.

The plasma processing apparatus, the antenna 20 of the gas 8 for plasma generation is disposed in the vacuum container 2 introduced by flowing a high-frequency current I _R through the matching circuit 58 from the RF power source 56, the vacuum chamber An inductive coupling type plasma 16 is generated by generating an induction electric field in the substrate 2, and the substrate 10 is processed using the plasma 16.

That is, when a high-frequency current I _{R is} passed through the antenna 20, a high-frequency magnetic field is generated around the antenna 20, thereby generating an induction electric field in a direction opposite to the high-frequency current I _R. Due to this induction electric field, electrons are accelerated in the vacuum chamber 2 to ionize the gas 8 in the vicinity of the antenna 20 and generate plasma (ie, inductively coupled plasma) 16 in the vicinity of the antenna 20. The plasma 16 diffuses to the vicinity of the substrate 10, and the substrate 10 can be processed by the plasma 16.

  The vacuum vessel 2 is, for example, a metal vessel, and the inside thereof is evacuated by the evacuation device 4. The vacuum vessel 2 is electrically grounded in this example.

  The substrate 10 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 10 is, for example, film formation by a plasma CVD method or the like, 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.

A gas 8 is introduced into the vacuum vessel 2 via, for example, a flow rate regulator (not shown) and a gas introduction pipe 6. The gas 8 may be introduced into the vacuum vessel 2 from one place, or may be introduced from a plurality of places (the illustrated example is three places, but is not limited thereto). The gas 8 may be in accordance with the content of processing performed on the substrate 10. For example, when film formation is performed on the substrate 10 by plasma CVD, the gas 8 is a gas obtained by diluting a source gas with a diluent gas (for example, H ₂ ). More specifically, when the source gas is SiH ₄ , the Si film is formed; when SiH ₄ + NH ₃ is used, the SiN film is formed; when SiH ₄ + O ₂ is used, the SiO ₂ film is formed; and when SiF ₄ + N ₂ is used, the SiN film is formed. : F film (fluorinated silicon nitride film) can be formed on the surface of the substrate 10, respectively.

  A substrate holder 12 that holds the substrate 10 is provided in the vacuum vessel 2. As in this example, a bias voltage may be applied to the substrate holder 12 from the bias power supply 14.

  The antenna 20 is a substantially straight antenna (in other words, a straight line), and in this example, near the upper portion in the vacuum vessel 2 so as to be along the surface of the substrate 10 (for example, substantially the same as the surface of the substrate 10). In parallel) and across the substrate 10. One or more antennas 20 may be arranged in the vacuum vessel 2. A plurality of embodiments will be described later.

  In this example, the antenna 20 includes an insulating pipe 22 and a hollow antenna body 24 that is disposed therein and into which cooling water 44 flows. A gap 23 is provided between the insulating pipe 22 and the antenna body 24.

  Examples of the material of the insulating pipe 22 include quartz, alumina, fluororesin, silicon nitride, silicon carbide, and silicon, but are not limited thereto.

  In short, the insulating pipe 22 is for preventing the antenna body 24 from coming into direct contact with the plasma 16. More specifically, 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 than the ions in the plasma and much more incident on the conductor, so the plasma potential is higher than the conductor. Ascend to the positive side. On the other hand, when the insulating pipe 22 as described above is provided, charged particles in the plasma 16 are incident on a metal pipe (for example, a metal pipe 26 described below) constituting the antenna body 24 by the insulating pipe 22. Therefore, it is possible to suppress an increase in plasma potential due to charged particles (mainly electrons) entering the metal pipe, and the metal pipe is sputtered by charged particles (mainly ions) to cause plasma 16. In addition, the occurrence of metal contamination (metal contamination) on the substrate 10 can be suppressed.

  The antenna body 24 may be formed of a metal pipe, and as in this example, (a) a plurality of metal pipes 26 are arranged between adjacent metal pipes 26 with a hollow insulator 28 (in FIGS. 5 and 6). (B) and a capacitor 30 electrically connected in series with the metal pipes 26 on both sides of the hollow insulator 28. Things can be used.

  Each connection portion between the metal pipe 26 and the hollow insulator 28 has a sealing function against the vacuum and the cooling water 44. This sealing function can be realized by a known sealing means. For example, a packing may be used, and a known pipe taper screw structure may be used.

  The number n of metal pipes connected in series (n is an integer of 2 or more) and the number of hollow insulators 28 and capacitors 30 (n−1) are n = 2 in the illustrated example, but n may be 3 or more.

  The material of the metal pipe 26 is, for example, copper, aluminum, alloys thereof, stainless steel or the like, but is not limited thereto.

  The material of the hollow insulator 28 is, for example, ceramics such as glass and alumina, fluororesin, polyethylene (PE), engineering plastic (for example, polyphenylene sulfide (PPS), polyetheretherketone (PEEK), etc.). It is not limited to.

  A specific example of the structure around the capacitor 30 will be described later with reference to FIGS.

  Both ends of the antenna main body 24 (that is, the metal pipe 26) are penetrated to the outside of the vacuum vessel 2, and an insulator 46 is provided in the penetrating portion. The metal pipe 26 and the insulator 46 of the antenna body 24 and the insulator 46 and the vacuum vessel 2 are vacuum-sealed by packings 48 and 50, respectively. The entire insulating pipe 22 is provided in the vacuum vessel 2.

A feeding end 51 which is one end of the antenna 20 is connected to a high frequency power source 56 via a matching circuit 58. In this example, the terminal portion 52 which is the other end portion of the antenna 20 is grounded via the coil 66, but may be grounded via a capacitor or directly grounded. Frequency of the high frequency current I _R supplied to the antenna 20 from the RF power source 56 is for example a common 13.56 MHz, the invention is not limited thereto.

Further, in this embodiment, the distances D ₁ and D ₂ are set between the antenna 20 and the antenna 20 at positions corresponding to both ends of the substrate 10 in the longitudinal direction of the antenna 20 in the longitudinal direction of the antenna 20. Auxiliary electrodes 70 are provided respectively. Each auxiliary electrode 70 is electrically grounded.

  Each auxiliary electrode 70 may be, for example, an annular (ring-shaped) electrode surrounding the antenna 20 as in the examples shown in FIGS. 1 and 2, or the substrate 10 side is open as in the example shown in FIG. A semi-cylindrical electrode surrounding the upper half of the antenna 20 may be used, and as shown in the example shown in FIG. 4, the antenna 20 is sandwiched along the antenna 20 and substantially perpendicular to the substrate surface. Alternatively, a pair of plate-like electrodes arranged may be used. Each auxiliary electrode 70 may be a pair of rod-shaped (for example, round bar-shaped) electrodes arranged so as to sandwich the antenna 20 along the antenna 20, or may have other shapes.

In the figure, the distance between the antenna 20 and the auxiliary electrode 70 near the feeding end 51 of the antenna 20 is D ₁ , and the length of the auxiliary electrode 70 in the direction along the antenna 20 is L ₁ . Further, the distance between the auxiliary electrode 70 near the terminal end 52 of the antenna 20 and the antenna 20 is D ₂ , and the length of the auxiliary electrode 70 in the direction along the antenna 20 is L ₂ .

  The material of each auxiliary electrode 70 is, for example, copper, aluminum, alloys thereof, stainless steel or the like, but is not limited thereto. Further, when the temperature rise of each auxiliary electrode 70 is large, the material of each auxiliary electrode 70 is preferably a refractory metal such as molybdenum or tantalum.

  A specific example of the structure of the capacitor 30 is shown in FIG. The capacitor 30 is a layered capacitor disposed on the outer peripheral portion of the hollow insulator 28, and (a) an electrode disposed on the outer peripheral portion of the hollow insulator 28, on one side of the hollow insulator 28. A first electrode 32 electrically connected to the connected metal pipe 26; and (b) an electrode disposed on the outer periphery of the hollow insulator 28 so as to overlap the first electrode 32, A second electrode 34 electrically connected to a metal pipe 26 connected to the other side of the hollow insulator 28; and (c) a dielectric 36 disposed between the first electrode 32 and the second electrode 34. And have.

  The capacitor 30 may have a structure in which electrodes 32 and 34 are formed on both main surfaces of a film-like dielectric 36 by metal deposition or the like and wound around the outer periphery of the hollow insulator 28 a predetermined number of times.

  The capacitor 30 may have a structure as shown in FIG. That is, when the connection portion between the one end portion of the hollow insulator 28 and the metal pipe 26 is referred to as a first connection portion 38 and the connection portion between the other end portion and the metal pipe 26 is referred to as a second connection portion 40, the capacitor 30 (A) A part of the metal pipe 26 on the first connection portion 38 side is also used as the first electrode of the capacitor 30, and (b) hollow from the outer peripheral portion of the metal pipe 26 on the first connection portion 38 side. A dielectric 36 provided in a region extending from the outer peripheral portion of the insulator 28; and (c) provided in a region extending from the outer peripheral portion of the dielectric 36 to the outer peripheral portion of the metal pipe 26 on the second connection portion 40 side. A second electrode having an area CA that is electrically connected to the metal pipe 26 on the second connection portion 40 side and overlaps the metal pipe 26 on the first connection portion 38 side with a dielectric 36 interposed therebetween. The electrode 34 is provided.

  The overlapping area CA can be called a capacitance forming area because a capacitance is formed there. In this capacitor 30, the portion of the metal pipe 26 including the capacitance forming area CA is also used as the first electrode of the capacitor.

  Referring again to FIG. 1 and the like, in this plasma processing apparatus, an inductively coupled plasma 16 is generated around the antenna 20 by passing a high-frequency current through the antenna 20 as described above. Diffuses in the vicinity.

In addition, by flowing a high-frequency current I _R through the antenna 20, the potential of the antenna 20 rises according to the impedance of the antenna 20 and the like, and a high-frequency electric field is generated between the antenna 20 and each auxiliary electrode 70 having the ground potential. Occur. The density of the plasma 16 generated by the inductive coupling mode is increased by this high-frequency electric field, more specifically by a so-called capacitive coupling mode (that is, a mode in which plasma is generated by a high-frequency electric field generated between conductors). Can be made. As a result, it is possible to suppress a decrease in plasma density in the vicinity of both end portions of the substrate 10 in the longitudinal direction of the antenna 20 and improve the uniformity of the plasma density distribution in the longitudinal direction of the antenna 20. As a result, the uniformity of the substrate processing by the plasma 16 can be improved. For example, when a film is formed on the substrate 10 using the plasma 16, the uniformity of the film thickness distribution can be improved. In addition, when the film on the substrate 10 is etched using the plasma 16, the uniformity of the etching rate distribution can be improved.

An example of the experimental results for the potential of the antenna 20 is increased by flowing a high frequency current I _R to the antenna 20 shown in FIG. This figure shows an example of an experimental result obtained by measuring the voltage (peak peak value of the high-frequency voltage) at the ends of the antenna 20 (the feed end 51 and the termination 52) when the termination coil 66 is present or absent. It is. The presence of the termination coil 66 means that the termination part 52 of the antenna 20 is grounded via the coil 66, and the absence of the termination coil 66 means that the termination part 52 is directly grounded without the coil 66. That is the case.

The main experimental conditions in this case are as follows.
The number of capacitors 30 included in the antenna 20: 3 (therefore, the number of metal pipes 26 is 4)
Insulating pipe 22 material: quartz Supplying high frequency power to antenna 20: 500 W
High frequency power frequency: 13.56 MHz
Gas supply into the vacuum chamber 2 and plasma lighting: None Coil 66 inductance: 180 nH

  As can be seen from this experimental result, the voltage shown in FIG. 8 is generated by the impedance of the grounding wire without the termination coil 66, but when the termination coil 66 is present, it is generated at both ends of the coil 66. The potential of the entire antenna 20 is greatly increased by the voltage, and the potential of the antenna 20 is about 1200V to 1400V. Therefore, compared to the case without the termination coil 66, it is easy to generate a strong high-frequency electric field between the antenna 20 and each auxiliary electrode 70 and to enhance the plasma density increasing action by the capacitive coupling mode described above.

1 to 4 again, the electric field strength between the antenna 20 and each auxiliary electrode 70 can be adjusted by adjusting the distances D ₁ and D ₂ between them.

Further, in order to improve the balance between the plasma density increasing action by the auxiliary electrode 70 on the side close to the power feeding end 51 of the antenna 20 and the plasma density increasing action by the auxiliary electrode 70 on the side close to the terminal end 52, At least one of the distances D ₁ and D ₂ and the lengths L ₁ and L ₂ may be adjusted. For example, when the voltage on the power supply end 51 side of the antenna 20 is higher than the voltage on the terminal end 52 side as in the example shown in FIG. 8, at least one of D ₁ > D ₂ and L ₁ <L ₂ is adopted. You may do it. You may use both together. The above method can be employed both when the antenna main body 24 is made of the metal pipe 26 and when the antenna main body 24 has the metal pipe 26, the hollow insulator 28, and the capacitor 30.

  The antenna body 24 may be (a) one that does not have the hollow insulator 28 and the capacitor 30, that is, one that includes a metal pipe 26, and (b) is described with reference to FIGS. 1, 5, and 6. Such a structure having the metal pipe 26, the hollow insulator 28 and the capacitor 30 may be used.

When the structure of (b) is used, the combined reactance of the antenna body 24 is simply obtained by subtracting the capacitive reactance of the capacitor 30 portion from the inductive reactance of the metal pipe 26 portion. The impedance and thus the impedance of the antenna 20 can be reduced, whereby the potential difference between both ends of the antenna 20 can be reduced. As a result, the uniformity of the plasma density distribution in the longitudinal direction of the antenna 20 can be improved, and the plasma density increasing action by the left and right auxiliary electrodes 70 can be easily balanced. Further, it is possible to suppress an increase in the impedance even if a longer antenna 20, a high-frequency current I _R tends to flow to the antenna 20, the inductively coupled plasma 16 can be efficiently generated. As a result, the efficiency of substrate processing can be increased.

  The terminal portion 52 of the antenna 20 may be (a) grounded via the coil 66 as in the above embodiment, (b) grounded via a capacitor, or (c) directly grounded. Also good. In the cases (a) and (b), the potential of the entire antenna 20 can be raised by the voltage generated at both ends of the coil 66 or the capacitor. Therefore, the electric field between the antenna 20 and each auxiliary electrode 70 is strengthened, and it becomes easy to strengthen the plasma density increasing action by the above-described capacitive coupling mode by each auxiliary electrode 70. In that case, since the antenna body 24 is usually inductive, the above-described action of raising the voltage is larger in the coil 66 of the above (a), and therefore, it is more preferable to ground the coil via the coil 66.

Each auxiliary electrode 70 may have a water cooling structure. Specifically, each auxiliary electrode 70 may be made hollow, and the auxiliary electrode 70 may be cooled by flowing cooling water therein. FIG. 1 shows an example of a hollow, water-cooled auxiliary electrode 70. When plasma density increasing action due to capacitive coupling mode described above by the auxiliary electrode 70, the high frequency current I _R flows through it or the like to the storage electrode 70, the auxiliary electrode 70 is heated. When the temperature rise of the auxiliary electrode 70 due to this heating is large, the material of each auxiliary electrode 70 may be a refractory metal such as molybdenum as described above, or may be a water-cooled structure as described above. If the water-cooling structure is adopted, the temperature rise of each auxiliary electrode 70 can be suppressed, so that the room for selecting the material of each auxiliary electrode 70 is widened. For example, it is possible to use a general metal such as aluminum, copper, or an alloy thereof other than the refractory metal for the material of each auxiliary electrode 70.

  Each auxiliary electrode 70 may be covered with an insulator 72 so as not to be in direct contact with the plasma 16. Examples thereof are shown in FIGS. The insulator 72 may be (a) a film formed on the surface of the auxiliary electrode 70, or (b) a case or pipe that covers the auxiliary electrode 70. In the case of the annular auxiliary electrode 70 as shown in FIG. 2, (a) is easier. In the case of (b), there may be a gap between the auxiliary electrode 70 and the insulator 72.

  The material of the insulator 72 is, for example, quartz, alumina, fluororesin, silicon nitride, silicon carbide, silicon or the like, but is not limited thereto.

  In addition, when the auxiliary electrode 70 is made of aluminum, the insulator 72 may be a film formed by alumite treatment. In addition, the film-like insulator 72 may be formed on the surface of the auxiliary electrode 70 by spraying an insulating material on the auxiliary electrode 70.

  By covering each auxiliary electrode 70 with the insulator 72, it is possible to suppress each auxiliary electrode 70 from being sputtered by the plasma 16 and mixing the metal constituting each auxiliary electrode 70 as an impurity into the plasma 16. . That is, the occurrence of metal contamination (metal contamination) can be suppressed.

  Furthermore, the surface of the insulator 72 may be covered with a substance that does not become a contamination source during film formation or etching.

  For example, when the plasma processing apparatus is an apparatus that forms a film on the substrate 10 using the plasma 16, the surface of the insulator 72 may be covered with the same material as the film to be formed or its component. good.

More specifically, a Si film (silicon film), a SiO ₂ film (silicon oxide film), a SiN film (silicon nitride film) or a SiN: F film (fluorinated silicon nitride film) is formed on the substrate 10. The surface of the insulator 72 may be coated with Si, SiO ₂ , SiN or SiN: F, which are the same kind of material as the film, or coated with the same kind of material as that of the film, for example, Si. You can keep it.

  In this manner, even if the surface of the insulator 72 is sputtered by the plasma 16, it is possible to suppress impurities other than the substances that constitute the film from being mixed into the film. Therefore, a high-quality film with few impurities can be formed.

  When the plasma processing apparatus is an apparatus that etches a film formed on the substrate 10 using the plasma 16, the surface of the insulator 72 is coated with the same type of material as the film to be etched or its components. You can keep it.

More specifically, when the film to be etched on the substrate 10 is a Si film, a SiO ₂ film, a SiN film or a SiN: F film, the surface of the insulator 72 is made of Si, which is the same kind of material as the film, The film may be coated with SiO ₂ , SiN or SiN: F, or may be coated with the same kind of material as the film component, for example, Si.

  As described above, even if the surface of the insulator 72 is etched by the plasma 16, only the material of the same type as that constituting the film is etched and exits as a gas. It is possible to suppress contamination. Therefore, etching with less contamination by impurities can be performed.

  FIG. 7 is a schematic cross-sectional view showing an embodiment of a plasma processing apparatus having a plurality of antennas 20. In the following, differences from the embodiment described above will be mainly described with reference to FIG.

  In this embodiment, a plurality of antennas 20 as described above are arranged in parallel in a direction along the surface of the substrate 10 (for example, substantially parallel to the surface of the substrate 10). In addition, the auxiliary electrode 70 as described above is provided for each antenna 20.

  Each auxiliary electrode 70 is an annular, water-cooled auxiliary electrode described with reference to FIG. 1 in this embodiment, but may be other auxiliary electrodes such as the semi-cylindrical shape, the plate shape, or the rod shape described above. When the auxiliary electrode 70 is plate-shaped or rod-shaped, the auxiliary electrode 70 between the two adjacent antennas 20 may be shared by both antennas 20.

  The number of antennas 20 arranged in parallel is not limited to four in the illustrated example, and may be two or more.

  The antenna main body 24 of each antenna 20 may have a capacitor 30 portion, or may be made of a metal pipe.

  The feeding end portions 51 of the plurality of antennas 20 may be connected to one high-frequency power source 56 through one matching circuit 58 as in this embodiment, and the matching circuit 58 is provided for each antenna 20. Also good. The terminal portions 52 of the plurality of antennas 20 may be individually grounded via the coil 66 as in this embodiment, or the plurality of terminal portions 52 may be grounded collectively via one coil 66. good. In the latter case, the number of coils 66 can be reduced. However, the method of supplying high-frequency power to the power supply end portions 51 of the plurality of antennas 20 and the method of grounding the termination portions 52 are not limited to the above example.

  According to this embodiment, a plurality of antennas 20 are arranged in parallel in the direction along the surface of the substrate 10, and the auxiliary electrode 70 is provided for each antenna 20. A good plasma 16 can be generated, and therefore, it is possible to cope with processing of a larger substrate 10.

2 Vacuum vessel 8 Gas 10 Substrate 16 Plasma 20 Antenna 22 Insulating pipe 24 Antenna body 26 Metal pipe 28 Hollow insulator 30 Capacitor 44 Cooling water 56 High frequency power supply 58 Matching circuit 66 Coil 70 Auxiliary electrode 72 Insulator

Claims (8)

An inductive electric field is generated in the vacuum vessel by flowing a high-frequency current through a substantially straight antenna disposed in the vacuum vessel to generate an inductively coupled plasma, and the substrate is processed using the plasma. A plasma processing apparatus,
Auxiliary that is electrically grounded with a gap between the antenna and the antenna at a position corresponding to the vicinity of both ends of the substrate in the longitudinal direction of the antenna in the vacuum vessel. A plasma processing apparatus comprising electrodes, respectively. The antenna has an insulating pipe and a hollow antenna body that is disposed therein and into which cooling water flows.
The antenna body has a structure in which (a) a plurality of metal pipes are connected in series with a hollow insulator interposed between adjacent metal pipes, and (b) the metal pipes on both sides of the hollow insulator. The plasma processing apparatus according to claim 1, further comprising a capacitor electrically connected in series with the plasma processing apparatus. The feeding end that is one end of the antenna is connected to a high-frequency power source,
The plasma processing apparatus according to claim 1, wherein a terminal portion that is the other end portion of the antenna is grounded through a coil.   The plasma processing apparatus according to claim 1, 2 or 3, wherein each of the auxiliary electrodes has cooling water flowing therein.   The plasma processing apparatus according to claim 1, wherein each auxiliary electrode is covered with an insulator. The plasma processing apparatus is an apparatus that forms a film on the substrate using the plasma,
The plasma processing apparatus according to claim 5, wherein a surface of the insulator is coated with a material of the same kind as the film or a component thereof. The plasma processing apparatus is an apparatus for etching a film formed on the substrate using the plasma,
The plasma processing apparatus according to claim 5, wherein a surface of the insulator is coated with a material of the same kind as the film or a component thereof. A plurality of the antennas are arranged in parallel in a direction along the surface of the substrate,
The plasma processing apparatus according to claim 1, wherein the auxiliary electrode is provided for each antenna.

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