JP2007273915A - Plasma treatment device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a Q-value of resonance from becoming excessively large, in a plasma treatment device for carrying out plasma treatment by means of resonance of fundamental waves or higher harmonic waves. <P>SOLUTION: The plasma treatment device 1 supplies high-frequency power from a high-frequency power source 26 to at least one of a pair of electrodes 20 and 12 placed vertically opposite in a treatment vessel 2 for generating a plasma P in the container 2 and processing a substrate. A variable impedance part 60 for varying the impedance on a side of an electrode, as viewed from the plasma P generated in the vessel 2 and a variable impedance circuit 40, having a resistor 61 connected in series, are provided in at least one of the pair of electrodes 20 and 12. The plasma treatment device 1 can prevent the Q-value of resonance from becoming excessively large, by providing the resistor 61 in the variable impedance circuit 40. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method for processing a substrate by generating plasma in a processing container.

  For example, in a manufacturing process of a semiconductor device, a liquid crystal display device, etc., plasma processing by a plasma processing apparatus is widely used for processing such as etching and film formation on a semiconductor wafer. In such a plasma processing apparatus, electrodes that are vertically opposed to each other are provided in a processing vessel. For example, high-frequency power is supplied to a lower electrode on which a substrate is placed, and plasma is generated between the lower electrode and the upper electrode to generate plasma. Processing is in progress.

  In this plasma processing apparatus, in order to improve the product yield, it is necessary to control the density distribution of the plasma generated in the processing container to improve the uniformity of the processing wafer surface. As one countermeasure for this, the present applicant has disclosed a method of changing the impedance of the fundamental wave from the high frequency power source and its harmonics on the electrode side viewed from the plasma generated in the processing vessel (patent) Reference 1).

JP 2004-96066 A

  In the processing chamber of the plasma processing apparatus, a fundamental wave of high-frequency power supplied to the electrode and various higher-order harmonics are generated during the plasma processing. According to the method disclosed in Patent Document 1, the fundamental wave from the high-frequency power source and the impedance to its harmonics on the electrode side as seen from the plasma generated in the processing container are changed, It is possible to selectively resonate the higher harmonics to maintain high in-plane uniformity of the plasma processing for the semiconductor wafer and to stably maintain the plasma state in the processing chamber.

  However, when the fundamental wave and harmonics are selectively resonated in this way, if the resonance Q value (resonance sharpness) becomes too large, even if the impedance viewed from the plasma is changed slightly, etching to the semiconductor wafer is performed. The speed will change greatly. The Q value of such resonance becomes particularly large in a low pressure (for example, 50 mT or less) and high power (for example, 500 W or more) process.

  Even if the plasma processing apparatus has the same specifications, the conditions in the processing vessel differ slightly for each plasma processing apparatus, but if the resonance Q value becomes too large as described above, In other words, a so-called machine difference problem occurs in which impedance control is greatly different. As a result, when a plurality of plasma processing apparatuses process a substrate in parallel, the processing state of the substrate may vary between apparatuses.

  Accordingly, an object of the present invention is to prevent the resonance Q value from becoming excessively large in a plasma processing apparatus that performs plasma processing using the above-described fundamental wave and harmonic resonance.

  In order to solve the above problems, according to the present inventor, high-frequency power is supplied from a high-frequency power source to at least one of a pair of electrodes arranged to be vertically opposed in a processing container, and plasma is generated in the processing container. A plasma processing apparatus for generating and processing a substrate, wherein at least one of the pair of electrodes is connected in series with a variable impedance portion and a resistor for changing impedance on the electrode side as viewed from plasma generated in the processing container. A plasma processing apparatus is provided, characterized in that a variable impedance circuit connected to is provided. According to this plasma processing apparatus, by providing the resistor in the variable impedance circuit, it is possible to prevent the resonance Q value from becoming excessively large.

  In this plasma processing apparatus, high-frequency power is supplied to both of the pair of electrodes from a high-frequency power source, and at least one of the pair of electrodes changes the impedance on the electrode side as viewed from the plasma generated in the processing container. A variable impedance unit and a resistor are connected in series, and the variable impedance circuit includes a fundamental wave of a high-frequency power source supplied to the opposing electrode, a harmonic to the fundamental wave, and a high-frequency power source supplied to its own electrode. The impedance on the electrode side viewed from the plasma generated in the processing container may be changed so that at least one of the harmonics of the fundamental wave resonates.

  Further, high-frequency power is supplied to one of the pair of electrodes from a high-frequency power source, and the impedance on the electrode side viewed from the plasma generated in the processing vessel is changed to the electrode opposed to the electrode to which the high-frequency power is supplied. A variable impedance circuit in which a variable impedance section to be connected and a resistor are connected in series is provided, and the variable impedance circuit is at least one of a fundamental wave of a high-frequency power source supplied to the opposing electrode and a harmonic with respect to the fundamental wave. The impedance on the electrode side viewed from the plasma generated in the processing vessel may be changed so that two high frequencies resonate.

  Also, a variable impedance unit that supplies high-frequency power to one of the pair of electrodes from a high-frequency power source, and changes the impedance on the electrode side viewed from the plasma generated in the processing container to the electrode to which the high-frequency power is supplied. And a variable impedance circuit in which a resistor is connected in series, and the variable impedance circuit generates plasma generated in the processing container so as to resonate harmonics with respect to a fundamental wave of a high-frequency power source supplied to its own electrode. The impedance on the electrode side as viewed from the above may be changed.

  The variable impedance circuit includes two or more variable impedance units that change impedance on the electrode side as viewed from plasma generated in the processing container, and the two or more variable impedance units have a frequency different from each other. Different high frequencies may be resonantly resonated.

  The variable impedance circuit may have a filter for selecting a high frequency to be resonated. Furthermore, the variable impedance circuit may have two or more types of filters for selecting high frequencies having different frequencies. Examples of the filter include a high pass filter, a low pass filter, and a band pass filter.

  In addition, according to the present invention, plasma for processing a substrate by supplying high-frequency power from a high-frequency power source to at least one of a pair of electrodes disposed vertically opposite in the processing container to generate plasma in the processing container. In the processing method, when a variable impedance portion connected to at least one of the pair of electrodes is used to change the impedance on the electrode side viewed from plasma generated in the processing container, the resistor is changed to the variable A plasma processing method is provided in which the Q value of resonance is lowered by connecting in series with an impedance unit.

  This plasma processing method has two or more variable impedance portions, and the two or more variable impedance portions resonate high frequencies having different frequencies, respectively, as viewed from the plasma generated in the processing container. The impedance on the electrode side may be changed.

  According to the present invention, it is possible to prevent the resonance Q value from becoming excessively large by providing the resistor in the variable impedance circuit that changes the impedance on the electrode side viewed from the plasma generated in the processing container. For this reason, it becomes easy to control the etching rate etc. with respect to a board | substrate, and also can suppress the problem of the so-called machine difference that impedance control differs for each plasma apparatus.

  Hereinafter, preferred embodiments of the present invention will be described. FIG. 1 is a longitudinal sectional view showing a schematic configuration of a plasma etching apparatus 1 as a plasma processing apparatus according to an embodiment of the present invention. FIG. 2 is a circuit configuration diagram of the high-frequency line 37 connected to the lower electrode 12. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, the plasma etching apparatus 1 includes a processing container 2 having a substantially cylindrical shape, for example. The inner wall surface of the processing container 2 is covered with a protective film such as alumina. The processing container 2 is electrically grounded.

  For example, a cylindrical electrode support 11 is provided at the bottom of the central portion in the processing container 2 with an insulating plate 10 interposed. On the electrode support 11, a lower electrode 12 is provided as a high-frequency electrode that also serves as a mounting table on which the substrate W is mounted. For example, the center of the upper surface of the lower electrode 12 protrudes in a cylindrical shape, and a substrate (semiconductor wafer) W is held by the protruding portion 12a. An annular focus ring 13 made of quartz is provided around the protruding portion 12 a of the lower electrode 12.

  For example, a substantially disk-shaped upper electrode 20 is attached to the ceiling of the processing container 2 facing the lower electrode 12 so as to make a pair with the lower electrode 12. An annular insulator 21 is interposed at a contact portion between the upper electrode 20 and the ceiling wall portion of the processing container 2, and the upper electrode 20 and the ceiling wall portion of the processing container 2 are electrically insulated.

  A first high frequency line 27 for supplying high frequency power for plasma generation from a first high frequency power supply 26 is electrically connected to the upper electrode 20 via a matching circuit 25. The first high frequency power supply 26 generates a high frequency power of 60 MHz, for example, and supplies the high frequency power to the upper electrode 20 for plasma generation.

  For example, a large number of gas discharge holes 30 are formed on the lower surface of the upper electrode 20. The gas discharge hole 30 communicates with a gas supply source 32 through a gas supply pipe 31 connected to the upper surface of the upper electrode 20. The gas supply source 32 stores a processing gas for the etching process. The processing gas introduced into the upper electrode 20 from the gas supply source 32 through the gas supply pipe 31 is supplied into the processing container 2 from the plurality of gas discharge holes 30.

  On the other hand, a second high frequency line 37 for supplying a high frequency power for bias from a second high frequency power supply 36 is electrically connected to the lower electrode 12 via a matching circuit 35. The second high frequency power source 36 generates high frequency power having a frequency lower than that of the first high frequency power source 26, for example, 13.56 MHz, and supplies the high frequency power to the lower electrode 12 for bias. The second high frequency power supply 28 may also generate plasma P in the processing container 2.

  The second high-frequency line 37 is provided with a variable impedance circuit 40 that changes the impedance of the lower electrode 12 as viewed from the plasma generated in the processing container 2 between the matching circuit 35 and the lower electrode 12. Yes.

  Here, the circuit configuration of the high-frequency line 37 connected to the lower electrode 12 will be specifically described. As shown in FIG. 2, the matching circuit 35 includes a first fixed coil 50, a first variable capacitor 51, and a second fixed coil 52. In the high-frequency line 37, the first fixed coil 50, the first variable capacitor 51, and the second fixed coil 52 are connected in series from the lower electrode 12 side toward the second high-frequency power source 36 side. Yes.

  Further, a second variable capacitor 56 and a fixed capacitor 57 are connected in parallel between both ends of the second fixed coil 52 and the ground 55. The matching circuit 35 has a function of automatically adjusting the impedance to, for example, 50Ω so that the high frequency power supplied from the second high frequency power source 36 to the lower electrode 12 does not cause reflection at the lower electrode 12. have.

  The variable impedance circuit 40 has a configuration in which a variable impedance unit 60, a resistor 61, and a filter 62 are connected in series between the high frequency line 37 and the ground 55. The filter 62 is cut so that a high frequency power of, for example, 13.56 MHz, which is a fundamental wave supplied from the second high frequency power supply 36 to the lower electrode 12, does not flow into the variable impedance unit 60, and has a frequency larger than this fundamental wave. For example, a high pass filter is used.

  As will be described later, high-frequency power for plasma generation (for example, high-frequency power of 60 MHz) is supplied from the first high-frequency power source 26 to the upper electrode 20, and the fundamental wave is applied to the lower electrode 12 from the second high-frequency power source 36. When the plasma P is generated in the processing vessel 2 by supplying high frequency power (for example, high frequency power of 13.56 MHz), the secondary, third, fourth, fifth, etc. with respect to the fundamental wave are generated from the plasma P. High-order harmonics such as The fundamental wave of the high frequency power for plasma generation and the harmonic high frequency power with respect to the fundamental wave pass through the filter 62 and are supplied to the variable impedance unit 60 in the variable impedance circuit 40 described above. At that time, the variable impedance unit 60 can change the impedance on the lower electrode 12 side as viewed from the plasma P so as to resonate with at least one of the fundamental wave and a plurality of higher harmonics. Is possible.

  In addition, as described above, the plasma P may be generated in the processing chamber 2 by the high frequency power for bias supplied from the second high frequency power supply 36 to the lower electrode 12. In such a case, the variable impedance unit 60 resonates the impedance on the lower electrode 12 side viewed from the plasma P with respect to at least one of higher harmonics with respect to the fundamental wave of the high frequency power for bias. It may be changed.

  The variable impedance unit 60 includes, for example, a fixed coil 65 having an inductance of approximately 200 nH and a variable capacitor 66. By changing the capacity of the variable capacitor 66, the lower electrode viewed from the plasma P generated in the processing container 2 is used. The impedance on the 12 side can be changed as appropriate. Here, the fundamental wave of the high frequency power for plasma generation supplied to the upper electrode 20, the harmonics of the fundamental wave of the high frequency power for plasma generation, and the high frequency power for bias supplied to the lower electrode 12 are fundamental. The impedance on the lower electrode 12 side as seen from the plasma can be adjusted by changing the capacitance of the variable capacitor 66 so that at least one of the harmonics to the wave can resonate.

  As shown in FIG. 1, an exhaust pipe 70 communicating with an exhaust mechanism (not shown) is connected to the lower portion of the processing container 2. By evacuating the inside of the processing container 2 through the exhaust pipe 70, the inside of the processing container 2 can be depressurized to a predetermined pressure.

  Next, the operation of the plasma etching apparatus 1 configured as described above will be described.

  When plasma etching is performed in the plasma etching apparatus 1, the substrate W is first carried into the processing container 2 and placed on the lower electrode 12 as shown in FIG. Then, the exhaust pipe 70 is evacuated to reduce the pressure in the processing container 2, and a predetermined processing gas supplied from the gas supply source 32 is supplied into the processing container 2 from the gas discharge hole 30. The first high frequency power supply 26 supplies, for example, high frequency power of 60 MHz for plasma generation to the upper electrode 20. On the other hand, the second high frequency power supply 36 supplies high frequency power of 13.56 MHz, for example, for bias to the lower electrode 12.

  Accordingly, high frequency power is applied between the lower electrode 12 and the upper electrode 20, and plasma P is generated between the lower electrode 12 and the upper electrode 20 in the processing container 2. The plasma P generates active species and ions from the processing gas, and etches the surface film of the semiconductor wafer W placed on the lower electrode 12. After the etching is performed for a predetermined time, the supply of the high frequency power to the upper electrode 20 and the lower electrode 12 and the supply of the processing gas into the processing container 2 are stopped, and the wafer W is unloaded from the processing container 2 and a series of The plasma etching process ends.

  Here, during the plasma etching process described above, the plasma P in the processing vessel 2 has higher harmonics such as second, third, fourth, fifth, etc. with respect to the fundamental wave of the high frequency power for plasma generation. A wave is generated. In some cases, higher-order harmonics such as second-order, third-order, fourth-order, fifth-order, etc. with respect to the fundamental wave of the high-frequency power for bias are also generated. The harmonics for the fundamental wave of the high frequency power for plasma generation, the harmonics for the fundamental wave of the high frequency power for bias, and the fundamental wave of the high frequency power for plasma generation are connected to the lower electrode 12 as described above. In the impedance circuit 40, the signal passes through the filter 62 and is supplied to the variable impedance unit 60. At that time, by adjusting the capacitance of the variable capacitor 66 provided in the variable impedance unit 60, the impedance on the lower electrode 12 side viewed from the plasma P is changed so as to resonate with at least one of the three. To do.

  By changing the impedance on the lower electrode 12 side as seen from the plasma P in this way, it is possible to resonate with respect to the above three, increase the etching rate, and maintain high uniformity of plasma processing on the wafer W. become. On the other hand, when the above three are selectively resonated, the etching rate increases, but if the resonance Q value becomes excessively large, the impedance on the lower electrode 12 side seen from the plasma P is slightly increased. Even if it changes, the etching rate with respect to the semiconductor wafer W will change a lot.

  However, such an excessive increase in the Q value can be prevented by the resistor 61 provided in the variable impedance circuit 40. Here, FIG. 3 shows the etching rate E. with respect to the semiconductor wafer W with respect to the impedance X on the lower electrode 12 side viewed from the plasma P. R. It is the graph which showed change of. In the vicinity of resonance, high-frequency power is suddenly supplied from the plasma P in the processing chamber 2 to the lower electrode 12 side. Therefore, as shown in FIG. E. R. Can be greatly increased.

  In this case, if the resonance Q value becomes excessively large, the etching rate E.E. R. However, the provision of the resistor 61 in the variable impedance circuit 40 suppresses the high-frequency power supplied from the plasma P in the processing chamber 2 to the lower electrode 12 side even in the vicinity of resonance. It will be. As a result, as indicated by the dotted line in FIG. R. Can be prevented from excessively increasing the resonance Q value. Therefore, the etching rate E.E. R. And the like, it becomes easy to adjust the impedance X on the lower electrode 12 side viewed from the plasma P.

  Further, by providing the resistor 61 in the variable impedance circuit 40, it is possible to suppress a so-called machine difference problem that impedance control differs for each plasma apparatus. For example, in FIG. 3, the matching accuracy of the impedance X is ΔX. That is, it is assumed that there is a variation in ΔX even though a plurality of devices are set to the same impedance X. Of course, ΔX is devised to make it as small as possible, but there is also the measurement accuracy of the measuring instrument, etc., and it cannot actually be set to 0, and is usually about 0.5Ω. On the other hand, the etching rate E. R. This variation in ΔX is caused by the etching rate E.E. R. Variation, that is, machine difference. According to the present invention, by inserting the resistor 61 in the variable impedance circuit 40, the change in resonance is reduced, and the etching rate E.P. R. Variation ΔE. R. Can be reduced. This variation ΔE. R. By selecting the resistance value of the resistor 61 so as to be equal to or less than the reference value (for example, 5%) of the machine difference for all recipes, the machine difference due to this phenomenon can be eliminated. Further, when adjusting the impedance X on the lower electrode 12 side as viewed from the plasma P, in addition to adjusting the above three to a complete resonance state, the impedance X is adjusted to an incomplete resonance state, for example, about 50% resonance state. Thus, the plasma state can be controlled arbitrarily, and the degree of resonance can be easily changed from 0 to 100%.

  Note that the resistance value of the resistor 61 is preferably set to about 0.5 to 5Ω, for example, in order to suppress the excessive increase of the resonance Q value and facilitate impedance control. In addition, since a normal winding type resistor does not operate effectively as a resistor for a high frequency band (for example, 0.4 to 100 MHz) used in an etching process, a resistor having good high frequency characteristics should be used. It is essential. In addition, it is necessary to pay attention to how to select the circuit constants of the impedance circuit 40 so that the resistance works only for the high frequency of the resonance frequency. That is, for a high frequency of a frequency that does not cause resonance, the impedance is increased by increasing the imaginary component of the impedance so that no current flows through the resistor 61. In this case, the impedance is set to, for example, 500Ω or more (the real number component of the resistor 61 is, for example, 5Ω or less as described above, but the imaginary number component is set to 500Ω or more (or −500Ω or less)).

  Since the variable impedance circuit 40 is provided with the filter 62, high frequency power of 13.56 MHz, for example, a fundamental wave supplied from the second high frequency power supply 36 to the lower electrode 12 is blocked by the filter 62. , Does not flow into the variable impedance unit 60. The high frequency power of the fundamental wave is discharged to the ground side through the upper electrode 20 and the side wall of the processing container 2.

  As mentioned above, although an example of preferable embodiment of this invention was demonstrated, this invention is not limited to the form illustrated here. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the spirit described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs. For example, in FIG. 2, the case where a series circuit of a variable capacitor 66 and a fixed coil 65 is used as the variable impedance unit 60 has been described. However, the present invention is not limited to this, and the variable impedance unit 60 is a lower electrode viewed from the plasma P. Any circuit that can change the impedance on the 12 side may be used.

  The variable impedance circuit 40 described with reference to FIG. 2 is a variable impedance unit 60 composed of one variable capacitor 66 and one fixed coil 65, and a fundamental wave of high frequency power for plasma generation supplied to the upper electrode 20, At least one of the harmonics with respect to the fundamental wave of the high frequency power for plasma generation and the harmonics with respect to the fundamental wave of the fundamental wave of the high frequency power for bias supplied to the lower electrode 12 is selectively resonated. However, instead of this, a plurality of variable impedance units may be provided so that impedance control can be performed independently for each harmonic. 4 to 6 are circuit diagrams showing modifications of the variable impedance circuit 40 having such a plurality of variable impedance units. 4 to 6 exemplify the variable impedance circuit 40 provided with three variable impedance units 60a, 60b, and 60c.

  In the variable impedance circuit 40 shown in FIG. 4, the first to third variable impedance units 60 a, 60 b, 60 c, the first to third resistors 61 a, 61 b, 61 c, The filters 62a, 62b and 62c are connected in parallel. Each of the first to third band pass filters 62a, 62b, and 62c passes different harmonics, and in this example, the first band pass filter 62a is a high frequency for bias supplied to the lower electrode 12. A high-frequency voltage in a frequency band centered on the second harmonic with respect to the fundamental wave of the fundamental wave of power is passed, and the second band-pass filter 62b is centered on the third harmonic wave with respect to the fundamental wave of the high-frequency power for bias. The third band-pass filter 62c is set to pass a high-frequency voltage in the frequency band centered on the fourth harmonic with respect to the fundamental wave of the high-frequency power for bias. Of course, the first to third band-pass filters 62a, 62b, and 62c do not pass the fundamental wave (13.56 MHz) of the high frequency power for bias. The first to third resistor elements 61a, 61b, 61c and the first to third variable impedance units 60a, 60b, 60c are individually connected in series to the first to third band-pass filters 62a, 62b, 62c. is doing. The first to third variable impedance units 60a, 60b, and 60c have first to third fixed coils 65a, 65b, and 65c and first to third variable capacitors 66a, 66b, and 66c, respectively. By changing the capacities of the first to third variable impedance units 60a, 60b, and 60c, the impedance on the lower electrode 12 side viewed from the plasma P generated in the processing container 2 is changed to the first to third variable impedance units 60a. , 60b and 60c can be changed.

  According to the variable impedance circuit 40 shown in FIG. 4, not only can the second harmonic to the fourth harmonic with respect to the fundamental wave of the high frequency power for biasing be selectively resonated, Any two or three harmonics of the second to fourth harmonics can be resonated simultaneously. Accordingly, it is possible to combine the characteristics of each harmonic with respect to the plasma processing.

  In the first to third variable impedance units 60a, 60b, and 60c, when the impedance on the lower electrode 12 side viewed from the plasma P generated in the processing container 2 is changed, the first to third resistors 61a, By providing 61b and 61c, it is possible to prevent the Q value of resonance from becoming excessively large. For this reason, for any of the second to fourth harmonics, the etching rate E.V. is adjusted by adjusting the impedance X on the lower electrode 12 side viewed from the plasma P. R. It becomes easy to control.

  The variable impedance circuit 40 shown in FIG. 5 has a configuration in which first to third filters 62 a, 62 b and 62 c are connected in series to the high frequency line 37. The first filter 62a is a high-pass filter that passes a frequency equal to or higher than the second harmonic of the fundamental wave of the high frequency power for bias, and the second filter 62b is the third harmonic of the fundamental wave of the high frequency power for bias. The third filter 62c is a high-pass filter that passes a frequency higher than the fourth harmonic with respect to the fundamental wave of the high frequency power for bias. The first variable impedance unit 60a and the first resistor 61a are connected between the first filter 62a and the second filter 62b, and between the second filter 62b and the third filter 62c. The second variable impedance unit 60b and the second resistor 61b are connected to each other, and the third variable impedance unit 60c and the third resistor 61c are connected to the downstream side of the third filter 62c.

  Also in the variable impedance circuit 40 shown in FIG. 5, as in the case described with reference to FIG. 4, one of the second to fourth harmonics with respect to the fundamental wave of the high frequency power for biasing is selectively selected. In addition to resonating the wave, any two or three of the second to fourth harmonics can be resonated simultaneously. Further, for any of the second to fourth harmonics, the etching rate E.P. R. It becomes easy to control.

  The variable impedance circuit 40 shown in FIG. 6 has a configuration in which the first to third filters 62 a, 62 b, 62 c are arranged in series in the high frequency line 37. The first filter 62a is a low-pass filter that passes a frequency equal to or lower than the fourth harmonic of the fundamental wave of the high frequency power for bias, and the second filter 62b is the third harmonic of the fundamental wave of the high frequency power for bias. The third filter 62c is a low-pass filter that passes frequencies below the second harmonic with respect to the fundamental wave of the high-frequency power for bias. Then, the first variable impedance unit 60a and the first resistor 61a are connected between the first filter 62a and the second filter 62b, and the second filter 62b and the third filter 62c are connected. The second variable impedance unit 60b and the second resistor 61b are connected to each other, and the third variable impedance unit 60c and the third resistor 61c are connected to the downstream side of the third filter 62c. Yes.

  Also in the variable impedance circuit 40 shown in FIG. 6, as in the case described with reference to FIGS. 4 and 5, one of the second to fourth harmonics with respect to the fundamental wave of the high frequency power for biasing is selectively 1. In addition to resonating two harmonics, any two or three of the second to fourth harmonics can be resonated simultaneously. Further, for any of the second to fourth harmonics, the etching rate E.P. R. It becomes easy to control.

  4 to 6, the variable impedance circuit 40 for passing the high frequency voltage in the frequency band of the 2nd to 4th harmonics with respect to the fundamental wave of the high frequency power for bias supplied to the lower electrode 12 has been described. The frequency band of the high-frequency voltage passed through the circuit 40 is not limited to the harmonic with respect to the fundamental wave of the high-frequency power for bias supplied to the lower electrode 12, but may be a harmonic with respect to the fundamental wave of the high-frequency power for plasma generation. Moreover, you may make it pass through the variable impedance circuit 40 combining those harmonics suitably.

  Although the case where the variable impedance circuit 40 is provided in the high frequency line 37 of the second high frequency power supply 36 has been described with reference to FIG. 1, the present invention is not limited to this and may be provided anywhere as long as the high frequency current flows. FIG. 7 shows an example in which a variable impedance circuit 40 is provided in the first high frequency line 27 for supplying high frequency power for plasma generation from the first high frequency power supply 26 to the upper electrode 20 instead of the high frequency line 37. . In the case of the example shown in FIG. 7, the variable impedance circuit 40 has three types other than the fundamental wave of the high frequency power for plasma generation supplied to the upper electrode 20 (high frequency for plasma generation supplied to the upper electrode 20). At least one of harmonics with respect to the fundamental wave of power, fundamental waves with high-frequency power for bias supplied to the lower electrode 12, and harmonics with respect to the fundamental wave of high-frequency power for bias) are selectively resonated. What is necessary is just to comprise.

  FIG. 8 shows an example in which the variable impedance circuit 40 is provided in the first high-frequency line 27 that supplies high-frequency power for plasma generation from the first high-frequency power supply 26 to the upper electrode 20 in addition to the high-frequency line 37. Show. As described above, the variable impedance circuit 40 can be provided in any of the high-frequency lines 27 and 37 that supply high-frequency power to the electrodes 12 and 20. In the case of the example shown in FIG. 7, the variable impedance circuit 40 provided in the first high-frequency line 27 has three other types (the upper electrode 20 except the fundamental wave of the high-frequency power for plasma generation supplied to the upper electrode 20. At least one of a harmonic with respect to a fundamental wave of high-frequency power for plasma generation supplied to the base, a fundamental wave with high-frequency power for bias supplied to the lower electrode 12, and a harmonic with respect to the fundamental wave of high-frequency power for bias). What is necessary is just to comprise so that one may selectively resonate. Further, the variable impedance circuit 40 provided in the second high-frequency line 37 has three types other than the fundamental wave of the high-frequency power for bias supplied to the lower electrode 12 (for generating plasma supplied to the upper electrode 20). At least one of a fundamental wave of the high-frequency power, a harmonic wave of the fundamental wave of the high-frequency power for plasma generation, and a harmonic wave of the fundamental wave of the high-frequency power for bias supplied to the lower electrode 12). What is necessary is just to comprise.

  In the above-described embodiment, an example in which the high-frequency power sources 26 and 36 are connected to both the upper electrode 20 and the lower electrode 12 has been described as an example. However, the present invention is not limited to this, and only one of the electrodes is used. Of course, the present invention can also be applied when a high-frequency power source is connected. When a high frequency power source is connected to only one of the electrodes as described above, a variable that changes the impedance on the electrode side viewed from the plasma P generated in the processing container 2 to the electrode that is opposed to the electrode to which the high frequency power is supplied. An impedance circuit 40 is provided. The variable impedance circuit 40 is configured to change the impedance on the electrode side so as to resonate at least one of the fundamental wave of the high-frequency power source supplied to the opposing electrode and the harmonic wave with respect to the fundamental wave. . Further, when a high frequency power source is connected to only one electrode, a variable impedance circuit 40 for changing the impedance on the electrode side viewed from the plasma P generated in the processing container 2 is provided on the electrode to which the high frequency power is supplied. Also good. In that case, the variable impedance circuit 40 is configured to change the impedance on the electrode side so as to resonate harmonics with respect to the fundamental wave of the high-frequency power source supplied to its own electrode. In the above embodiment, the present invention is applied to the plasma etching apparatus 1. However, the present invention can also be applied to a plasma processing apparatus that performs substrate processing other than etching processing, for example, film formation processing. Further, the substrate processed by the plasma processing apparatus of the present invention may be any of a semiconductor wafer, an organic EL substrate, a substrate for FPD (flat panel display), and the like.

  The present invention can be applied to plasma processing in which plasma is generated in a processing container to process a substrate.

It is a longitudinal section showing a schematic structure of a plasma etching device concerning an embodiment of the invention. It is a circuit block diagram of the high frequency line connected to a lower electrode. Etching rate with respect to impedance X on the lower electrode side as seen from plasma E.E. R. It is the graph which showed change of. It is a circuit diagram which shows the modification of a variable impedance circuit. It is a circuit diagram which shows another modification of a variable impedance circuit. It is a circuit diagram which shows another modification of a variable impedance circuit. It is a longitudinal cross-sectional view which shows the schematic structure of the plasma etching apparatus concerning Embodiment which provided the variable impedance circuit in the 1st high frequency line. It is a longitudinal cross-sectional view which shows the schematic structure of the plasma etching apparatus concerning Embodiment which provided the variable impedance circuit in the 1st high frequency line and the 2nd high frequency line.

Explanation of symbols

P Plasma 1 Plasma etching apparatus 2 Processing vessel 10 Insulating plate 11 Support base 12 Lower electrode 13 Focus ring 20 Upper electrode 21 Insulator 25 Matching circuit 26 First high frequency power supply 27 First high frequency line 30 Gas discharge hole 31 Gas supply pipe 32 Gas supply source 35 Matching circuit 36 Second high frequency power supply 37 Second high frequency line 40 Variable impedance circuit 50 First fixed coil 51 First variable capacitor 52 Second fixed coil 55 Ground 56 Second variable capacitor 57 Fixed capacitor 69 Variable impedance part 61 Resistor 62 Filter 65 Fixed coil 66 Variable capacitor 70 Exhaust pipe

Claims (10)

A plasma processing apparatus for processing a substrate by supplying high-frequency power from a high-frequency power source to at least one of a pair of electrodes arranged vertically opposite in a processing container, generating plasma in the processing container,
A variable impedance circuit in which a variable impedance section for changing impedance on the electrode side viewed from plasma generated in the processing vessel and a resistor are connected in series to at least one side of the pair of electrodes. And plasma processing equipment. High frequency power is supplied from a high frequency power source to both of the pair of electrodes,
The variable impedance circuit is provided on at least one side of the pair of electrodes,
The variable impedance circuit includes at least one of a fundamental wave of a high-frequency power source supplied to an opposing electrode, a harmonic wave with respect to the fundamental wave, and a harmonic wave with respect to a fundamental wave of a high-frequency power source supplied to its own electrode. On the other hand, the impedance on the electrode side as viewed from the plasma generated in the processing container is changed, The plasma processing apparatus according to claim 1, wherein Supplying high frequency power from a high frequency power source to one of the pair of electrodes;
The variable impedance circuit is provided on the electrode facing the electrode to which the high-frequency power is supplied,
The variable impedance circuit is configured to detect at least one of a fundamental wave of a high-frequency power source supplied to the opposing electrode and a harmonic with respect to the fundamental wave, as viewed from the plasma generated in the processing container. The plasma processing apparatus according to claim 1, wherein the impedance on the electrode side is changed. Supplying high frequency power from a high frequency power source to one of the pair of electrodes;
The variable impedance circuit is provided on the electrode side to which the high frequency power is supplied,
The variable impedance circuit is characterized in that the impedance on the electrode side viewed from the plasma generated in the processing vessel is changed with respect to a harmonic with respect to a fundamental wave of a high frequency power source supplied to its own electrode. The plasma processing apparatus according to claim 1. The variable impedance circuit includes two or more variable impedance units that change impedance on the electrode side as viewed from plasma generated in the processing container, and the two or more variable impedance units have a frequency different from each other. The plasma processing apparatus according to claim 2, wherein different high frequencies are resonated. The plasma processing apparatus according to claim 2, wherein the variable impedance circuit includes a filter for selecting a high frequency to be resonated. The plasma processing apparatus according to claim 2, wherein the variable impedance circuit includes two or more types of filters for selecting harmonics having different frequencies. The plasma processing apparatus according to claim 6 or 7, wherein the filter is any one of a high-pass filter, a low-pass filter, and a band-pass filter. A plasma processing method for processing a substrate by supplying a high-frequency power from a high-frequency power source to at least one of a pair of electrodes arranged to face each other in a processing container so as to generate plasma in the processing container,
A variable impedance unit connected to at least one of the pair of electrodes is used to connect a resistor in series with the variable impedance unit when changing the impedance on the electrode side viewed from the plasma generated in the processing container. A plasma processing method characterized in that the Q value of resonance is lowered. The electrode-side impedance viewed from the plasma generated in the processing container has two or more variable impedance portions, and the two or more variable impedance portions resonate high frequencies having different frequencies. The plasma processing method according to claim 9, wherein the plasma processing method is changed.

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