JP2008251830A - Plasma treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma treatment apparatus capable of generating highly uniform plasma with a high density, while suppressing adhering substances on a dielectric member in radical etching and/or low-speed etching with low substrate bias. <P>SOLUTION: The plasma treatment apparatus is provided with a dielectric member for defining a plasma treatment space in a vacuum container; a first electrode disposed outside the dielectric member and having a spiral coil shape, having a first applying point of high-frequency power at its center; and a planar second electrode, disposed in between the first electrode and the dielectric member so that its center coincides with the center of the first electrode and having a second applying point of high-frequency power disposed symmetric with its center. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus that generates plasma in a plasma processing space and performs plasma processing on an object.

  Conventionally, as a plasma processing apparatus that generates high-density plasma in a plasma processing space and performs plasma processing such as vapor deposition, etching, sputtering, etc. on an object placed in the plasma processing space, for example, a substrate or the like, Things are known.

  As such a plasma processing apparatus, for example, there is a high-frequency inductively coupled plasma processing apparatus that generates plasma in a vacuum vessel by applying high-frequency power to a discharge coil (see, for example, Patent Document 1). This type of plasma processing apparatus generates a high-frequency magnetic field in a vacuum vessel, generates an induction electric field in the vacuum vessel by the high-frequency magnetic field, accelerates electrons, and generates plasma.

  In such a conventional plasma processing apparatus, when performing plasma processing mainly using Ar-based gas which is general plasma processing, metal atoms sputtered on the substrate are dielectric members. There is a case in which the problem arises that the inductively coupled discharge cannot be maintained for a long time due to adhesion to the quartz plate. A method for suppressing such adhesion of metal atoms or the like to the surface of the quartz plate has been proposed. For example, in Patent Document 2, by disposing another electrode (FS electrode) that is electrostatically coupled (capacitively coupled) with plasma between a loop-shaped discharge coil and a quartz plate, There has been disclosed a plasma processing apparatus in which a self-bias is formed on the surface and ions are actively attracted to remove deposits attached to the inner surface.

  In such a conventional plasma processing apparatus, power of about 600 to 800 w is supplied to the discharge coil, for example, and power of about 200 to 400 w is supplied to the FS electrode, so that the etching rate is, for example, 200 to 300 nano / min. It is possible to achieve a high-speed etching with a substantially uniform etching rate.

Japanese Patent No. 3165356 Japanese Patent No. 3429391

  However, using such a conventional plasma processing apparatus, when performing radical etching and / or low-speed etching with a low substrate bias, that is, plasma processing that performs fine etching with low power is performed. In such a case, there is a problem that the etching rate becomes non-uniform. This is because there is no particular problem when high-speed etching is performed using high power, and there is a slight balance of plasma power (for example, plasma density) due to the latent discharge coil and FS electrode. It is considered that non-uniformity has become apparent when performing low-speed etching using low power. The low-speed etching means that an electric power of about 200 to 400 w, for example, is supplied to the discharge coil, and an electric power of about 200 to 400 w is supplied to the FS electrode, so that an etching rate of about 20 to 50 nano / min can be obtained. Such etching.

  Accordingly, an object of the present invention is to solve the above-mentioned problems, and in high-density etching while suppressing deposits on the dielectric member in radical etching and / or low-speed etching with a low substrate bias. An object of the present invention is to provide a plasma processing apparatus capable of generating plasma with high uniformity.

  In order to achieve the above object, the present invention is configured as follows.

According to the first aspect of the present invention, in a plasma processing apparatus for generating plasma in a plasma processing space and performing plasma processing on an object,
A vacuum vessel in which the object is placed;
A dielectric member defining a plasma processing space in the vacuum vessel;
A first electrode disposed outside the dielectric member and having a spiral coil shape having a first application point of high-frequency power at its center;
A second high-frequency power second wave disposed between the first electrode and the dielectric member so that its center coincides with the center of the first electrode and symmetrically disposed with respect to the center. There is provided a plasma processing apparatus comprising a plate-like second electrode having an application point.

  According to a second aspect of the present invention, there is provided the plasma processing apparatus according to the first aspect, wherein in the second electrode, the second application point is arranged at the center.

  According to a third aspect of the present invention, in the second electrode, the plasma processing apparatus according to the first aspect, wherein a plurality of the second application points are arranged at equal intervals around the center. provide.

  According to a fourth aspect of the present invention, the first electrode is a three-dimensional coil having a pyramid shape with the central portion at the top, according to any one of the first to third aspects. A plasma processing apparatus is provided.

  According to a fifth aspect of the present invention, the first electrode according to any one of the first to fourth aspects, wherein the first electrode is a multiple spiral coil formed point-symmetrically with respect to the center. A plasma processing apparatus is provided.

  According to the sixth aspect of the present invention, the second electrode has at least three slit-like shapes formed extending in a direction orthogonal to the arrangement direction of the coil member of the first electrode. A plasma processing apparatus according to any one of the first to fifth aspects, comprising an opening.

  According to a seventh aspect of the present invention, there is provided the plasma processing apparatus according to the sixth aspect, wherein a part of each of the slit-like openings is opened at the end of the flat plate-like second electrode. provide.

  According to an eighth aspect of the present invention, the plasma processing according to the sixth or seventh aspect, wherein the respective slit-like openings are arranged at equal intervals around the center of the second electrode. Providing equipment.

  According to the ninth aspect of the present invention, in the second electrode, the conductor region sandwiched between the two slit-shaped openings adjacent to each other is more than the opening region of the one slit-shaped opening. The plasma processing apparatus according to any one of the sixth to eighth aspects is also provided.

  According to the present invention, the first application point of the high frequency power to the first electrode having the spiral coil shape is arranged at the center, and the plate-like shape is arranged between the first electrode and the dielectric member. By arranging the second application point of the high-frequency power to the second electrode symmetrically with respect to the center of the first electrode, for example, point-symmetrically, the power of inductive coupling by the first electrode, The balance with respect to the said center with the power of the capacitive coupling by a 2nd electrode can be made favorable. Therefore, the plasma density in the plasma processing space can be made uniform, and the etching rate on the surface of the plasma processing object can be made uniform. In particular, this uniform etching rate is effective in radical etching and / or low-speed etching with a low substrate bias, and is high from low-power low-speed etching while suppressing deposits on the dielectric member. A plasma processing apparatus capable of generating high-density and high-uniformity plasma over a wide range up to high-speed etching of power can be provided.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

(First embodiment)
A schematic configuration diagram showing a main configuration of the plasma processing apparatus 101 according to the first embodiment of the present invention is shown in FIG.

  As shown in FIG. 1, the plasma processing apparatus 101 includes a chamber 1 that is an example of a vacuum container that forms a plasma processing space S inside thereof, and a dielectric that defines the plasma processing space S by closing an upper opening of the chamber 1. A quartz top plate 5 that is an example of a body member, an ICP coil (inductive coupling coil) 4 that is an example of a first electrode that is disposed outside (upward in the drawing) of the top plate 5 and has a spiral coil shape, and ICP An FS electrode 7 which is an example of a flat plate-like second electrode disposed between the coil 4 and the top plate 5 is provided.

  In the chamber 1, a counter electrode (substrate electrode or third electrode) 3 on which a substrate 2 is placed, for example, is disposed as opposed to the ICP coil 4, and is opposed to this. The electrode has an electrostatic chuck (ESC) 9 that electrostatically holds the mounted substrate (wafer) 2. The counter electrode 3 has, for example, a disk shape, and is electrically connected to the counter electrode high-frequency power source 15 via the variable capacitor 16 with the lower center portion in the figure as the third application point 3a. High frequency power is applied. Further, in the chamber 1, a gas supply port 1a for supplying, for example, a chlorine-based gas G as a reaction gas to the plasma processing space S inside thereof, and the plasma processing space S are decompressed to a predetermined pressure, for example, in a vacuum state An exhaust port 1b is formed. The gas supply port 1a is connected to a gas supply unit (not shown), and the exhaust port 1b is connected to an exhaust unit (not shown).

  Here, a schematic perspective view showing the ICP coil 4, the FS electrode 7, and the top plate 5 in a partially disassembled state is shown in FIG. As shown in FIGS. 1 and 2, the ICP coil 4 is a three-dimensional structure formed by a plurality of strip-shaped conductor members (coil members) 8 such that the overall appearance of the ICP coil 4 is a cone, for example, a cone. Type coil. Each coil member (for example, four coil members) 8 is arranged so as to turn in the same direction from one central position which is the top, with the width direction as a vertical direction, and the central position is symmetrical. A point-symmetrical multi-coil with the center of is formed. Further, with this center position as the first application point 4a of the high frequency power, the ICP coil high frequency power supply 11 is electrically connected through the variable capacitor 12, and a predetermined high frequency power is applied. . Further, the spiral outer peripheral ends of the coil members 8 in the ICP coil 4 are grounded. Thus, by applying high frequency power to the apex of the center position of the three-dimensional coil (ICP coil 4), the plasma distribution under the top plate 5 of the dielectric member directly under the ICP coil 4 becomes too high locally. High power can be applied without adverse effects.

  The FS electrode 7 is a thin disk-shaped electrode formed of a conductive material so that the outer shape thereof becomes slightly smaller along the outer shape of the top plate 5. The center position of the FS electrode 7 is arranged on the top surface of the top plate 5 in a state of being positioned so as to coincide with the center position of the ICP coil 4 (that is, the first application point 4a) in the vertical direction. Further, with the center position of the FS electrode 7 as the second application point 7a of the high frequency power, the FS electrode high frequency power supply 13 is electrically connected via the variable capacitor 14 so that a predetermined high frequency power is applied. It has become. Further, as shown in FIG. 2, the FS electrode 7 is formed with six slits 7b formed in the radial direction so as to extend from the disc-shaped outer peripheral end portion toward the center position. . Each of the slits 7b is formed, for example, with the same shape and size, and is arranged point-symmetrically with respect to the second application point 7a that is the center position. The six conductor regions 7c are arranged in a state of being electrically connected to the second application point 7a so as to be sandwiched between the slits 7b adjacent to each other. The FS electrode 7 and the top plate 5 may be in contact with each other or may be separated from each other, but the ICP coil 4 and the FS electrode 7 are at least not electrically connected. They are spaced apart from each other. The FS electrode is formed, for example, as a copper or aluminum metal plate.

  Here, the planar arrangement relationship of the ICP coil 4, the FS electrode 7, and the top plate 5 is shown in the schematic diagram of FIG. As shown in FIG. 3, in the first embodiment, the first application point 4a of the ICP coil 4 and the second application point 7a of the FS electrode 7 are arranged to coincide with each other in the vertical direction. Further, these positions also coincide with the center position of the top plate 5. Further, the ICP coil 4 which is a three-dimensional multiple coil has a higher arrangement density of the coil members 8 on the outer peripheral side than in the vicinity of the center position. The slits 7b of the FS electrode 7 are arranged so that the opening portion of the FS electrode 7 exists at least at a position corresponding to a dense portion of the coil member 8 and a position in the vicinity thereof.

  Next, in describing the effects of the plasma processing apparatus 101 according to the first embodiment, the functions of the ICP coil 4 and the FS electrode 7 will be described with reference to schematic explanatory views shown in FIGS. 4, 5, and 6 </ b> A to 6 </ b> C. I will explain.

  First, as shown in FIG. 4, when a high frequency power is applied from the high frequency power supply 11 to the ICP coil 4, a magnetic field is generated around the coil member 8, and the magnetic field is passed through the top plate 5 which is a dielectric member. As a result, a high-density plasma P is generated. Thus, the ICP coil 4 has a function of generating plasma by inductive coupling.

  On the other hand, the FS electrode 7 has a function of removing deposits attached to the inner surface of the top plate 5 by capacitive coupling. More specifically, as shown in FIG. 6A, when plasma is generated in the plasma processing space S by inductive coupling of the ICP coil 4, metal atoms and the like adhere to the surface of the top plate 5 to form metal. A film 10 is formed. Such adhesion of the metal film 10 inhibits maintenance of inductive coupling. In such a situation, when the FS electrode and the generated plasma P are capacitively coupled through the top plate 5, as shown in FIGS. 6B and 6C, self-bias (bias) is applied to the inner surface of the top plate 5. The potential Vdc) is formed and charged negatively, and the ions M are drawn from the plasma P, whereby the metal film 10 attached to the top plate 5 can be removed.

  Such a function by capacitive coupling of the FS electrode 7 is realized in the conductor region 7c. On the other hand, the FS electrode 7 also has a function of blocking the magnetic field formed by the ICP coil 4 in the conductor region 7c. Therefore, in the FS electrode 7 of the first embodiment, an opening, that is, a slit 7b is formed in the portion where the coil members 8 of the ICP coil 4 are densely arranged along the direction in which the magnetic field is formed. Thus, it is possible to effectively remove deposits by capacitive coupling while effectively transmitting the magnetic field 19 formed by the ICP coil 4 into the plasma processing space S.

  A procedure for performing plasma processing on the substrate 2 in the plasma processing apparatus 101 of the first embodiment having such a configuration will be described.

  First, in FIG. 1, the substrate 2 is placed on the counter electrode 3 in the chamber 1, and the substrate 2 is held by the electrostatic chuck 9. Thereafter, the air in the sealed chamber 1 is exhausted through the exhaust port 1b, and the plasma processing space S is made a vacuum atmosphere. At the same time, the chlorine-based gas G is supplied to the plasma processing space S through the gas supply port 1a. After the plasma processing space S is set to an atmosphere of a predetermined condition, a high frequency power of, for example, 13.56 MHz is applied to the ICP coil 4, and inductive coupling is performed by a magnetic field that has passed through the slit 7b of the FS electrode to generate plasma P. Is done. Plasma processing is performed on the substrate 2 by the generated plasma P. At the same time, high-frequency power is applied to the FS electrode 7 to suppress adhesion of deposits on the top plate 5 due to capacitive coupling.

  In the plasma processing apparatus 101 of the first embodiment, the relationship between the plasma density distribution due to the ICP power of the ICP coil 4, the plasma density distribution due to the FS power of the FS electrode 7, and the plasma density distribution due to the IPC power and the FS power is shown. It shows to Fig.7 (a)-(c). In the figure, the position P0 indicates the center position of the IPC coil 4, the FS electrode 7, and the wafer (substrate) 2, and the position P1 indicates the outer peripheral end position. Further, the plasma density distribution due to the ICP power shown in FIG. 7A and the plasma density distribution due to the FS power shown in FIG. 7B are at position A (position just below the top plate) in the plasma processing apparatus 101 of FIG. The plasma density distribution by ICP power and FS power shown in FIG. 7C is a distribution at the B position (position on the substrate) in the plasma processing apparatus 101 of FIG.

  In the ICP coil 4, the first application point 4 a is disposed at the center position thereof, and further has a conical shape. Therefore, the distance between the center position and the top plate 5 is the outer peripheral portion. And the distance between the top plate 5 and the top plate 5 is larger. Furthermore, as shown in FIGS. 2 and 3, the coil density on the outer periphery of the ICP coil 4 is higher than that inside the coil. Further, the magnetic field blocking effect is enhanced by the vicinity of the center of the FS electrode 7 being the conductor region 7c without being provided with the slit 7b. Therefore, as shown in FIG. 7A, the ICP power (power by inductive coupling (inductive coupling energy)) transmitted from the ICP coil 4 into the plasma processing space S is the center position P0 at the outer peripheral end position P1. And the distribution is symmetrical with respect to the center position P0.

  In the FS electrode 7, the second application point 7a is disposed at the center position. Therefore, as shown in FIG. 7B, the FS power (power by capacitive coupling (capacitive coupling energy)) transmitted from the FS electrode 7 into the plasma processing space S is at a central position P0 close to the application point 7a. It is the highest, decreases with increasing distance from the application point 7a, and becomes the lowest at the outer peripheral end position P1. In the FS electrode 7 as well, the power distribution is symmetric with respect to the center position P0.

  Here, as a plasma processing apparatus 151 according to the comparative example of the first embodiment, a schematic plan view of a plasma processing apparatus in which the second application point 157a in the FS electrode 157 is disposed at one location near the outer peripheral end. Is shown in FIG. 18, and a schematic configuration diagram (partially exploded view) is shown in FIG. As shown in FIGS. 18 and 19, the plasma processing apparatus 151 according to the comparative example is different in the arrangement of the second application point 157a of the FS electrode 157, and the other configuration is the plasma processing of the first embodiment. It is the same as the device 101.

  In the plasma processing apparatus 151 of such a comparative example, as shown in FIG. 20A, the configuration of the ICP coil 4 is the same, so the distribution of ICP power (inductive coupling power) by the ICP coil 4 is as shown in FIG. It is the same as 7 (a). However, since the arrangement of the second application point 157a of the FS electrode 157 is greatly deviated from the center position, as shown in FIG. 20B, the FS power (capacitive coupling power) is at the position of the second application point 157a. ) Is the maximum value, and the power decreases toward the center position P0 and the end position P1 on the opposite side. Therefore, in the comparative example, such a tendency toward the lower left also appears in the plasma density distribution in the vicinity of the surface of the wafer 2 (position B), and a uniform etching rate cannot be realized.

  Here, it will be described with reference to FIGS. 28A to 28C that the plasma density distribution in the plasma processing apparatus 151 of the comparative example is not uniform. As shown in FIG. 28A, in the plasma processing apparatus, the plasma generated just below the top plate (dielectric member) (position A) by only the ICP power of the ICP coil diffuses in the plasma processing space in a vacuum state. In addition, a substantially uniform plasma density distribution is obtained in the vicinity of the wafer surface (position B). Such a tendency of the plasma density distribution does not change greatly even when the power applied to the ICP coil is changed from high power (H) to low power (L). On the other hand, as shown in FIG. 28B, the plasma generated just below the top plate (position A) by only the FS power of the FS electrode is farther from the position of the application point in the vicinity of the wafer surface (position B). The plasma density distribution decreases. When the ICP power is high, the plasma density distribution due to the FS power having such a gradient distribution becomes latent, and as a result, as shown at H in FIG. The plasma density distribution due to the FS power is in a uniform state. However, when the ICP power becomes low, the plasma density distribution due to the FS power having a gradient distribution becomes obvious. As a result, as shown by L in FIG. 28C, the plasma due to the ICP power and FS power in the vicinity of the wafer surface. The density distribution is non-uniform. As described above, since the ICP power becomes low power, the non-uniform plasma density due to the FS power that has existed at the time of high power becomes obvious, so that a uniform etching rate is obtained in the plasma processing apparatus of the comparative example. I can't.

  On the other hand, in the first embodiment, since the application point is arranged at the center position of the FS electrode 7, the plasma density distribution due to the FS power can be made uniform. Therefore, even when the ICP power is low, the difference between the FS electrode outer peripheral side and the FS electrode center in the plasma density distribution near the surface of the wafer 2 (position B) can be reduced. Therefore, as shown in FIG. 7C, in the plasma processing apparatus of the first embodiment, the plasma density in the plasma processing space S can be made uniform, and the etching rate on the surface of the wafer 2 is made uniform. Can be realized.

  Further, the arrangement of the second application point 7a in the center position of the FS electrode 7 is such that the ICP coil 4 is formed as a conical three-dimensional coil instead of a planar coil. It can be realized by securing a wiring route so as to pass through, and does not affect the inductive coupling function of the ICP coil 4.

  In addition, since the ICP coil 4 employs a multiple spiral type coil structure, power transmission is not performed only on the outer periphery as in the case of the loop type coil, but also in the vicinity of the center position. Therefore, the etching rate can be made uniform.

  Furthermore, since the FS electrode 7 is formed in a disk shape, effective capacitive coupling can be realized, and a high suppression effect of deposits on the top plate 5 can be obtained. At the same time, the plurality of slits 7b are formed in a uniform location along the direction of the magnetic field, that is, in the radial direction, in the dense location of the coil member 8 in the ICP coil 4, so that the FS electrode 7 is disposed, The magnetic field formed by the ICP coil 4 can be effectively transmitted to the plasma processing space S through the slit 7b.

  Therefore, the slight non-uniformity of the plasma power balance caused by the ICP coil and the FS electrode that has become apparent in the low-speed etching can be solved. Therefore, in radical etching as represented by plasma treatment using chlorine-based gas and / or low-speed etching with low substrate bias, high density and high uniformity while suppressing deposits on the top plate It is possible to provide a plasma processing apparatus capable of generating the plasma.

(Second Embodiment)
In addition, this invention is not limited to the said 1st Embodiment, It can implement in another various aspect. For example, the configuration (partially disassembled configuration) of the ICP coil, the FS electrode, and the top plate included in the plasma processing apparatus 102 according to the second embodiment of the present invention is shown in the schematic perspective view of FIG. A schematic plan view showing the relationship is shown in FIG. 8 and 9, the same reference numerals are assigned to the same components as those included in the plasma processing apparatus 101 of the first embodiment, and the description thereof is omitted.

  As shown in FIGS. 8 and 9, in the plasma processing apparatus 102 of the second embodiment, only the configuration of the FS electrode 27 is different from that of the first embodiment. Specifically, in the FS electrode 27, the second application point 27a of the high frequency power is individually disposed in the vicinity of the outer peripheral end portion of each conductor region 27c sandwiched between the slits 27b. The second application points 27 a, the slits 27 b, and the conductor regions 27 c are arranged symmetrically with respect to the center position of the FS electrode 27.

  In such a plasma processing apparatus 102 of the second embodiment, as shown in FIGS. 10A to 10C, the power applied at multiple points on the outer periphery of the FS electrode 27 is applied at the application point 27a. It becomes the largest at (outer peripheral end position P1). Therefore, the ICP power inductively coupled at more points can be efficiently transmitted to the plasma processing space S at the outer peripheral end position P1 where the ICP power transmitted from the ICP coil 4 to the plasma processing space S becomes large. . In addition, since the power applied uniformly at multiple points at the outer peripheral end position is collected near the center position of the FS electrode 27, a decrease in FS power at the center position where the application point is not arranged is suppressed. The As a result, the plasma density distribution in the vicinity of the wafer surface by ICP power and FS power can be made uniform as a whole while being slightly lowered at the center position. Therefore, the etching rate on the surface of the wafer 2 can be made uniform. In particular, the application of high-frequency power to the FS electrode 27 is made multipoint, and the position of each application point 27a is arranged symmetrically with respect to the center position, thereby suppressing the plasma power. Plasma processing suitable for thin-film wafer etching at a high-accuracy low-speed etching rate can be realized.

(Third embodiment)
Next, FIG. 11 is a schematic plan view showing a planar arrangement relationship of the ICP coil, the FS electrode, and the top plate included in the plasma processing apparatus 103 according to the third embodiment of the present invention. In FIG. 11, the same reference numerals are assigned to the same components as those included in the plasma processing apparatus of the above embodiment, and the description thereof is omitted.

  As shown in FIG. 11, in the plasma processing apparatus 103 of the third embodiment, only the configuration of the FS electrode 37 is different from that of the second embodiment. Specifically, in the FS electrode 37, the second application point 37a of the high frequency power is near the center of each conductor region 37c sandwiched between the slits 37b (intermediate between the center of the FS electrode and the outer peripheral end). Position). Further, the second application point 37a, the slit 37b, and the conductor region 37c are arranged in a point-symmetric manner with respect to the center position of the FS electrode 37, which is the same as in the second embodiment.

  In such a plasma processing apparatus 103 of the third embodiment, as shown in FIGS. 12A to 12C, the power applied at multiple points by the FS electrode 37 is applied to the application point 37a (P1 and P1). It becomes the largest at the intermediate position of P0. Therefore, the effect of suppressing the decrease of the FS power at the center position can be enhanced as compared with the second embodiment, and the plasma density in the plasma processing space S can be made substantially uniform. Therefore, the uniformity of the etching rate on the surface of the wafer 2 can be further improved.

(Fourth embodiment)
Next, a schematic cross-sectional view of an ICP coil, an FS electrode, and a top plate included in a plasma processing apparatus 104 according to the fourth embodiment of the present invention is shown in FIG. 13B, and a schematic plan view of the ICP coil 44 is shown in FIG. 13A. .

  As shown in FIGS. 13A and 13B, in the plasma processing apparatus 104 of the fourth embodiment, an ICP coil 44 having a planar spiral coil shape is employed instead of a three-dimensional spiral coil. This is different from the above embodiments.

  Further, as shown in FIG. 13B, for example, the FS electrode 27 of the second embodiment shown in FIG. 9 is used as the FS electrode, and the outer peripheral end portion is arranged in a point-symmetric manner to be multipointed. A plurality of second application points 27a are provided.

  In the ICP coil 44 having such a planar coil shape, it is difficult to secure a space between the coil members 48, and therefore the arrangement of the application point 27a of the FS electrode 27 is on the outer peripheral end side. However, since the respective second application points 27a are arranged point-symmetrically with respect to the center position, more uniform power can be transmitted to the plasma processing space S and a uniform low-speed etching rate can be realized. can do. The first application point 44a in the ICP coil 44 is disposed at the center position.

  Various other forms can be applied as such a planar coil shape. For example, in the plasma processing apparatus 105 shown in FIGS. 14A and 14B, a coil having a planar multiple spiral coil shape in which a plurality of coil members 58 are swung in multiple directions from the center position is adopted as the ICP coil 54. .

  Further, in the plasma processing apparatus 106 shown in FIGS. 15A and 15B, as the ICP coil 64, one coil member 68 is swung from the center position and further divided into a plurality of coil members 68 in the middle of the turn. A coil having a shape of a swirled plane type multiple spiral coil is employed. As shown in FIG. 15A, the ICP coil 64 has a feature that the coil density near the center is low and the coil density near the outer periphery is high.

  Even when such various types of planar spiral coils are employed as ICP coils, the effects of the fourth embodiment can be obtained.

  Here, from the first embodiment to the arrangement and application points of the second application points 7a, 27a, and 37a of the FS electrodes 7, 27, and 37 in the plasma processing apparatuses 101, 102, and 103 of the third embodiment. The wiring route will be described with reference to schematic cross-sectional views shown in FIGS. 16A, 16B, and 16C.

  First, in the plasma processing apparatus 102 of the second embodiment shown in FIG. 16A, since the second application point 27a of the FS electrode 27 is arranged at the outer peripheral end, wiring to each second application point 27a is performed. The route R1 can be secured outside the ICP coil 4. Therefore, in such a form, it can be said that the degree of freedom of the wiring route is high.

  Next, in the plasma processing apparatus 103 of the third embodiment shown in FIG. 16B, since the second application point 37a of the FS electrode 37 is disposed at the intermediate position, wiring to each second application point 37a is performed. The route R2 is desirably secured at an intermediate position inside the ICP coil 4. In order to secure such a space for the wiring route R2, it is preferable to employ a spiral coil having a low coil density near the center and a high coil density near the outer periphery as the ICP coil. It is more desirable to employ a three-dimensional coil.

  In addition, in the plasma processing apparatus 101 of the first embodiment shown in FIG. 16C, the second application point 7a of the FS electrode 7 is disposed at the center position, and therefore the wiring route R3 to the second application point 7a. Is preferably secured near the center position inside the ICP coil 4. In order to ensure such a space for the wiring route R3, as described above, it is desirable to employ a coil having a coil density or a three-dimensional coil.

  Next, in each of the above embodiments, the form of the slit formed in the FS electrode will be described using a partially enlarged schematic explanatory view in which the vicinity of the slit of the FS electrode in FIGS. 17A and 17B is enlarged.

  First, as shown in FIG. 17A, for example, in the FS electrode 27 of the second embodiment, the end portion of the slit 27b is opened at the outer peripheral end portion of the FS electrode 27 (“open slit”). ”). On the other hand, as in the FS electrode 77 shown in FIG. 17B, a configuration in which the end of the slit 77b is not opened (referred to as a “closed slit”) can be employed. However, when the closed-type slit 77b is employed, the slit arrangement and shape should be determined so that the opening is sufficiently secured in the portion where the coil density of the ICP coil 4 is high and in the vicinity thereof. Is desirable. In a case where a sufficient opening is not ensured in the closed slit, the shielding effect of the magnetic field (shielding effect) is increased and the inductive coupling function may be lowered because the outer peripheral end is not opened. is there.

  The shape of such a slit is not limited to a rectangular shape, and various other shapes such as a triangular shape and an elliptical shape can be employed. In consideration of uniform capacitive coupling, the slits are preferably arranged point-symmetrically with respect to the center position of the FS electrode. As the plurality of slits, three or more, for example, about 6 or 8 are provided. It is preferable that the slits are arranged. Furthermore, in the FS electrode, it is preferable that the size of the slit is determined so that the total slit area is smaller than the total area of the conductor regions. This is because the conductor region portion contributes to capacitive coupling.

  Further, in determining the width of the slit 7b, it is necessary to consider the thickness of the top plate 5. When the thickness of the top plate 5 is large, the potential obtained by capacitive coupling is low, but the variation in the potential of capacitive coupling between the slit forming position and the conductor region forming position is reduced. On the other hand, when the thickness of the top plate 5 is small, the potential obtained by capacitive coupling can be increased, but the variation increases conversely.

  Moreover, it is preferable that the top plate 5 is formed thin considering that power such as a magnetic field is effectively transmitted into the plasma processing space S. On the other hand, considering that it can sufficiently withstand the vacuum pressure of the plasma processing space S, it is preferable that the thickness be formed thick. As a structure satisfying such conflicting conditions, for example, a structure in which a plurality of beams are provided radially on the top plate can be employed. In other words, at the position where the beam is formed, the top plate thickness is increased to ensure strength, and in the region between the beam, the top plate thickness is reduced to achieve efficient power transmission. be able to. For the top plate having such a beam structure, the slits of the FS electrodes are positioned at the portions where the top plate thickness between the beams is thin in consideration of the efficient permeability of the magnetic field. Thus, it is desirable to determine the formation position and number of slits.

  Further, in the above description, the case where the spiral shape of the ICP coil is circular has been described, but instead of such a case, the present invention can be applied to the present invention even when the spiral shape is square. it can.

  Here, the relationship between the arrangement of the application point of the high frequency power in the FS electrode and the plasma density in the vicinity of the wafer surface (B position) obtained as a result is summarized in the graph of FIG. As shown in FIG. 29, in the configuration S3 (comparative example) in which the application point is arranged only at one end portion of the FS electrode, the plasma density distribution is inclined, and a uniform etching rate cannot be obtained. On the other hand, in the form S1 (first embodiment) in which the application point is arranged at the center position, although the plasma density is slightly high near the center position P0, a substantially uniform plasma density distribution can be obtained as a whole. it can. In the form S2 (second embodiment) in which a plurality of application points are arranged on the outer periphery of the FS electrode, the plasma density is slightly high near the end position P1, but a substantially uniform plasma density distribution is obtained as a whole. be able to. Therefore, according to each of the above embodiments, a substantially uniform etching rate can be obtained.

  In each of the above embodiments, the film material is a magnetic material such as “nickel, gold, platinum, iridium or an alloy thereof, a nickel alloy (eg, nickel cobalt, nickel ferrite)” or a ferroelectric such as SbT or PzT. It is effective for plasma processing in which the material is used. These materials are non-volatile materials such as precious metals, and such a film material is a material in which deposits are likely to be generated, and the deposit suppressing effect by the FS electrode can be obtained. Particularly in such film processing, uniform etching at low speed is required, and it is preferable to apply the plasma treatment of the present invention. In addition, as such low-speed etching, it is preferable to perform etching using a chlorine-based gas in order to suppress adhesion of the nonvolatile film to the sidewall.

(Example)
Next, as Example 1 of the present invention, the variation in etching rate was measured when the plasma processing apparatus 101 of the first embodiment performed low-speed etching using a chlorine-based gas. Further, as Comparative Example 1 with respect to Example 1, a case where etching was performed using an Ar-based gas in the plasma processing apparatus 151 of FIG. 18, and as Comparative Example 2, chlorine-based gas was used in the plasma processing apparatus 151. The etching rate variation when etching was performed was measured. Note that a silicon wafer (PR mask: 1.6 μm, Ni alloy: 30 nm, base: SiO ₂ , diameter: φ6 inches) was used in common as an object for plasma treatment.

(Comparative Example 1)
Plasma treatment was performed on the wafer under the following etching conditions.
[Gas conditions]: 50 sccm (Ar)
[Pressure]: 0.4 Pa
[ICP coil applied power]: 600w
[FS electrode applied power]: 200w
[Counter electrode applied power]: 200 w
Further, as shown in FIG. 21, the second application point 157a of the FS electrode 157 was provided only at one location in the vicinity of the outer peripheral end portion, and high frequency power was applied. After performing the plasma treatment on the wafer 2, as shown in the schematic diagram of FIG. 22, a total of nine measurements in the vicinity of the surface of the wafer 2, with four locations in the X direction and four locations in the Y direction, based on the center position. A dot was provided and the etching rate was measured. The results are shown in the graph of FIG. In the graph of FIG. 23, the horizontal axis indicates the position of the measurement point of the wafer 2 separately in the X direction and the Y direction on the basis of the center position, and the vertical axis indicates the etching rate.

  As shown in FIG. 23, in the case of the plasma treatment using the Ar-based gas of Comparative Example 1, there is no uneven etching rate in the X direction and the Y direction even under low speed conditions where the power of the counter electrode is lowered, and high uniformity. was gotten.

(Comparative Example 2)
Next, as Comparative Example 2, plasma processing was performed on the wafer under the following etching conditions.
[Gas conditions]: 10 sccm (Cl ₂ )
40 sccm (BCl ₃ )
[Pressure]: 0.4 Pa
[ICP coil applied power]: 400w
[FS electrode applied power]: 200w
[Counter electrode applied power]: 300 w
Further, as shown in FIG. 24, only one second application point 157a of the FS electrode 157 is provided in the vicinity of the outer peripheral end portion, and high frequency power is applied. After performing the plasma treatment on the wafer 2, as shown in the schematic diagram of FIG. 22 as in the comparative example 1, four locations in the X direction and 4 in the Y direction are used in the vicinity of the surface of the wafer 2 with reference to the center position. A total of nine measurement points were provided, and the etching rate was measured. The result is shown in the graph of FIG.

  As shown in FIG. 25, in the case of plasma processing by low-speed etching using the chlorine-based gas of Comparative Example 2, the etching rate is not biased in the X direction, but biased in the Y direction. The etching rate near the application point 157a in the FS electrode 157 was high, and the etching rate became lower as the distance from the application point was increased.

Example 1
Next, as Example 1 of the present invention, a plasma treatment was performed on the wafer under the following etching conditions.
[Gas conditions]: 10 sccm (Cl ₂ )
40 sccm (BCl ₃ )
[Pressure]: 0.4 Pa
[ICP coil applied power]: 400w
[FS electrode applied power]: 200w
[Counter electrode applied power]: 300 w
In addition, as shown in FIG. 26, only one second application point 7a of the FS electrode 7 is provided at the center position, and high frequency power is applied. After performing the plasma treatment on the wafer 2, as shown in the schematic diagram of FIG. 22 in the same manner as in the comparative examples 1 and 2, four locations in the X direction and Y direction in the vicinity of the surface of the wafer 2 with reference to the center position. A total of nine measurement points were provided in 4 and the etching rate was measured. The result is shown in the graph of FIG.

  As shown in FIG. 27, in the case of the plasma processing by the low-speed etching using the chlorine-based gas of the example, there is no uneven etching rate in the X direction and the Y direction, and high uniformity is obtained. Therefore, according to the present invention, it was confirmed that high uniformity of the etching rate can be obtained in the low-speed etching.

  It is to be noted that, by appropriately combining arbitrary embodiments of the various embodiments described above, the effects possessed by them can be produced.

The schematic block diagram of the plasma processing apparatus concerning 1st Embodiment of this invention. The partial exploded view of the plasma processing apparatus of 1st Embodiment The schematic top view which shows the planar arrangement | positioning relationship of the ICP coil of the plasma processing apparatus of 1st Embodiment, an FS electrode, and a top plate. Model explanatory drawing of the plasma processing method of 1st Embodiment Schematic explanatory diagram of the plasma processing method of the first embodiment (figure of FS electrode) Model explanatory drawing of the plasma processing method of 1st Embodiment Model explanatory drawing of the plasma processing method of 1st Embodiment Schematic explanatory diagram of the plasma processing method of the first embodiment (partial enlarged schematic diagram) The graph which shows the effect by the plasma processing of 1st Embodiment The partial exploded view of the plasma processing apparatus concerning 2nd Embodiment of this invention The schematic top view which shows the planar arrangement | positioning relationship of the ICP coil of the plasma processing apparatus of 2nd Embodiment, an FS electrode, and a top plate. The graph which shows the effect by the plasma processing of 2nd Embodiment The schematic top view which shows the planar arrangement | positioning relationship of the ICP coil of the plasma processing apparatus of 3rd Embodiment, an FS electrode, and a top plate. The graph which shows the effect by the plasma processing of 3rd Embodiment The schematic plan view of the planar coil with which the plasma processing apparatus concerning 4th Embodiment of this invention is provided. Schematic configuration diagram of the plasma processing apparatus of the fourth embodiment Schematic plan view of a planar coil according to a modification of the fourth embodiment The schematic block diagram of the plasma processing apparatus of the modification of 4th Embodiment Schematic plan view of a planar coil according to a modification of the fourth embodiment The schematic block diagram of the plasma processing apparatus of the modification of 4th Embodiment Model explanatory drawing which shows the wiring route to the FS electrode of 2nd Embodiment Model explanatory drawing which shows the wiring route to the FS electrode of 3rd Embodiment Schematic explanatory drawing showing the wiring route to the FS electrode of the first embodiment Model explanatory drawing which shows the structure of the slit of the FS electrode of 2nd Embodiment Model explanatory drawing which shows the modification of the structure of the slit of the FS electrode of 2nd Embodiment The schematic top view which shows the planar arrangement | positioning relationship of the ICP coil of the plasma processing apparatus concerning the comparative example of 1st Embodiment, an FS electrode, and a top plate. Partial exploded view of the plasma processing apparatus of the comparative example Graph showing effect of plasma treatment of comparative example The figure which shows the position of the application point of the FS electrode of the comparative example 1 The figure which shows the measuring point in the wafer of the comparative example 1 The figure which shows the variation in the etching rate of the comparative example 1 The figure which shows the position of the application point of the FS electrode of the comparative example 2 The figure which shows the variation in the etching rate of the comparative example 2 The figure which shows the position of the application point of FS electrode of Example 1 of this invention The figure which shows the variation in the etching rate of Example 1 Graph illustrating the influence of the ICP power level on the plasma density distribution in the comparative example The graph which shows the relationship between arrangement | positioning of the application point to FS electrode, and plasma density

Explanation of symbols

1 chamber 2 substrate (wafer)
DESCRIPTION OF SYMBOLS 3 Counter electrode 4 ICP coil 4a 1st application point 5 Top plate 7 FS electrode 7a 2nd application point 7b Slit 7c Conductor area 8 Coil member 9 Electrostatic chuck 10 Metal film 11 High frequency power supply 12 for ICP coil Variable capacitor 13 FS High frequency power supply for electrode 14 Variable capacitor 15 High frequency power supply for counter electrode 16 Variable capacitor 101 Plasma processing apparatus P Plasma M Ion S Plasma processing space

Claims (9)

In a plasma processing apparatus for generating plasma in a plasma processing space and performing plasma processing on an object,
A vacuum vessel in which the object is disposed, and
A dielectric member defining a plasma processing space in the vacuum vessel;
A first electrode disposed outside the dielectric member and having a spiral coil shape having a first application point of high-frequency power at its center;
A second high-frequency power second wave disposed between the first electrode and the dielectric member so that the center thereof coincides with the center of the first electrode and symmetrically disposed with respect to the center. A plasma processing apparatus comprising: a plate-like second electrode having an application point.   The plasma processing apparatus according to claim 1, wherein in the second electrode, the second application point is arranged at the center.   2. The plasma processing apparatus according to claim 1, wherein a plurality of the second application points are arranged at equal intervals around the center in the second electrode.   The plasma processing apparatus according to any one of claims 1 to 3, wherein the first electrode is a three-dimensional coil having a conical shape with a central portion at the top.   5. The plasma processing apparatus according to claim 1, wherein the first electrode is a multiple spiral coil formed point-symmetrically with respect to the center. 6.   The said 2nd electrode is provided with the at least 3 or more slit-shaped opening part extended and formed in the direction orthogonal to the arrangement direction of the coil member of the said 1st electrode. The plasma processing apparatus as described in any one of these.   The plasma processing apparatus according to claim 6, wherein a part of each of the slit-like openings is opened at an end of the flat plate-like second electrode.   The plasma processing apparatus according to claim 6 or 7, wherein the respective slit-shaped openings are arranged at equal intervals around the center of the second electrode.   9. The device according to claim 6, wherein, in the second electrode, a conductor region sandwiched between two slit-shaped openings adjacent to each other is larger than an opening region of one slit-shaped opening. The plasma processing apparatus as described in any one.

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