Plasma processing device

Abstract

An objective of the present invention is to provide technology for controlling a plurality of high-frequency powers having different frequencies.　One of plasma processing devices according to the present invention comprises: a processing chamber in which a sample is subjected to plasma processing; a first high-frequency power supply that supplies high-frequency power of a first frequency to a first electrode via a first impedance matching device and a first filter; a second high-frequency power supply that supplies a second high-frequency power of a second frequency to a second electrode via a second impedance matching device and a second filter; and a sample stage on which the sample is placed, wherein a third filter, a first inductor, and a variable capacitor are arranged in series between the second filter and the second electrode, a fourth filter and a second inductor are arranged in series between the second filter and the second electrode and arranged in parallel with the third filter and the first inductor, and a transmission path between the first filter and the first electrode is connected to a transmission path between the second filter and the third filter.

Description

Plasma processing equipment

[0001] The present invention relates to a plasma processing apparatus.

[0002] Improving the uniformity of the etching process within the wafer surface has been a long-standing challenge in plasma etching systems. One method for improving uniformity within the wafer surface is to divide the electrode into multiple parts and adjust the RF power applied to each part to control the strength and distribution of the electric field within the wafer surface. Other methods include changing the frequency of the RF power applied to the electrode or superimposing RF power of different frequencies.

[0003] As an example, Patent Document 1 aims to provide a plasma processing apparatus or plasma processing method with improved yield, and discloses the following content regarding the plasma processing apparatus and plasma processing method: "A plasma processing apparatus or processing method for processing a wafer to be processed, which is placed on a sample stage surface disposed in a processing chamber inside a vacuum vessel, using plasma formed in the processing chamber, wherein during the processing, the wafer is processed by adjusting high frequency power supplied to a first electrode disposed inside the sample stage and a second electrode connected via a circuit in which a capacitor and a coil are disposed inside a dielectric ring-shaped member disposed on the outer periphery of the sample stage mounting surface and are arranged in series in this order."

[0004] Japanese Patent Application Laid-Open No. 2021-48411

[0005] In Patent Document 1, impedance is reduced by generating resonance in a circuit in which a capacitor and a coil are arranged in series. Therefore, there is still room for improvement in terms of adjusting high-frequency power to frequencies other than the resonance frequency. Therefore, an object of the present invention is to provide a technology for controlling multiple high-frequency powers of different frequencies.

[0006] In order to solve the above-mentioned problems, one representative plasma processing apparatus of the present invention includes a processing chamber in which a sample is plasma-processed, a first high-frequency power supply that supplies high-frequency power of a first frequency to a first electrode via a first impedance matching device and a first filter having a cutoff frequency of a second frequency, a second high-frequency power supply that supplies second high-frequency power of a second frequency to a second electrode via a second impedance matching device and a second filter having a cutoff frequency of the first frequency, and a sample stage on which the sample is placed, characterized in that a third filter, a first inductor, and a variable capacitor are arranged in series between the second filter and the second electrode, a fourth filter and a second inductor are arranged in series between the second filter and the second electrode and in parallel with the third filter and the first inductor, and a transmission line between the first filter and the first electrode is connected to a transmission line between the second filter and the third filter.

[0007] According to the present invention, it is possible to control a plurality of high frequency powers having different frequencies. Problems, configurations, and effects other than those described above will become apparent from the following description of the preferred embodiment of the invention.

[0008] FIG. 1 is a diagram showing a conventional configuration when power is applied to divided electrodes. FIG. 2 is a diagram showing a frequency characteristic of the gain of a resonant circuit. FIG. 3 is a diagram showing an example of high-frequency power applied to a first electrode and a second electrode. FIG. 4 is a diagram showing the configuration of a plasma processing apparatus according to a first embodiment. FIG. 5 is a diagram showing a frequency characteristic of the gain of a resonant circuit. FIG. 6 is a diagram showing the configuration of a plasma processing apparatus according to a first modification. FIG. 7 is a diagram showing the configuration of a plasma processing apparatus according to a second modification. FIG. 8 is a diagram showing the configuration of a plasma processing apparatus according to a third modification. FIG. 9 is a diagram showing the configuration of a plasma processing apparatus according to a fourth modification. FIG. 10 is a diagram showing the configuration of a plasma processing apparatus according to a fifth modification. FIG. 11 is a diagram showing a frequency characteristic of the gain of a resonant circuit. FIG. 12 is a diagram showing the configuration of a plasma processing apparatus according to a sixth modification.

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to these embodiments. In addition, in the description of the drawings, identical parts are denoted by the same reference numerals. When there are multiple components having the same or similar functions, they may be described by using the same reference numerals with different subscripts. Furthermore, when it is not necessary to distinguish between these multiple components, the subscripts may be omitted. The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc., in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] (Prior Art) First, the prior art will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a diagram showing a conventional configuration when applying power to divided electrodes. High frequency power output from a high frequency power supply 103 is impedance matched in an impedance matching device 104 and branched in a capacitor section 105 consisting of a fixed capacitance capacitor C and a variable capacitor VC. The power then passes through an inductor section 106 consisting of a fixed inductance inductor L and a variable inductor VL, and is applied to a first electrode 101 and a second electrode 102, respectively.

[0011] The variable capacitor VC of the capacitor section 105 and the inductor L and variable inductor VL of the inductor section 106 are connected in series to function as a resonant circuit 107. Figure 2 is a diagram showing a schematic diagram of the frequency characteristics of the gain of the resonant circuit 107. When the capacitance of the resonant circuit 107 is C ０ and the inductance is L ０ In this case, the resonant frequency f ０ is expressed as in equation (1). The impedance of the resonant circuit 107 is ０ Therefore, if the gain of the resonant circuit 107 is plotted on the vertical axis and the frequency of the input power on the horizontal axis, the gain is ０ The resonant frequency f of the resonant circuit 107 is ０can be adjusted by changing the capacitance of the variable capacitor VC or the inductance of the variable inductor VL. For example, when the capacitance of the variable capacitor VC or the inductance of the variable inductor VL is decreased, the resonant frequency f ０ becomes larger, and the frequency characteristic shifts (offsets) from the solid curve to the dashed curve. Also, for example, when the capacitance of the variable capacitor VC is increased or the inductance of the variable inductor VL is increased, the resonant frequency f ０ becomes smaller, and the frequency characteristic shifts from the solid curve to the dashed curve.

[0012] FIG. 3 is a diagram schematically illustrating an example of the high-frequency power applied to the first electrode 101 and the second electrode 102. A straight line 301 indicates the high-frequency power applied to the first electrode 101, and a curve 302 indicates the high-frequency power applied to the second electrode 102. In FIG. 3, the high-frequency power is shown as a high-frequency output voltage Vpp (Voltage peak to peak) [V]. In a typical structure, as shown in FIG. 3, when the high-frequency output voltage Vpp [V] applied to the first electrode 101 is α, the constant of the resonant circuit 107 is adjusted so that the high-frequency output voltage Vpp applied to the second electrode 102 can be adjusted within a range of 0.5 to 2.0 times. However, because the resonant circuit 107 has only a single resonant frequency, it can only be adjusted to a specific frequency. Therefore, it is difficult to supply an appropriate high-frequency output voltage Vpp to the second electrode 102 at other frequencies. Furthermore, when adjusting the magnification over a wide range, the range of change of the variable capacitor VC must be made correspondingly large. For example, when adjustment is desired for multiple frequencies, a measure has been taken to provide a mechanism for changing the circuit in the capacitor section 105 or the inductor section 106, but since this involves switching using hardware, it takes time to switch and is therefore not suitable for practical use.

[0013] First Embodiment Next, a first embodiment will be described with reference to FIGS.

[0014] 4 is a diagram showing the configuration of a plasma processing apparatus according to a first embodiment. The plasma processing apparatus 400 includes a processing chamber in which a sample is plasma-processed, a first high-frequency power supply 403 that supplies high-frequency power of a first frequency A (hereinafter also simply referred to as "A [Hz]") to a first electrode 401 via a first impedance matching device 405 and a first filter 408 whose cutoff frequency is a second frequency B (hereinafter also simply referred to as "B [Hz]"), a second high-frequency power supply 404 that supplies second high-frequency power of a second frequency B to a second electrode 402 via a second impedance matching device 406 and a second filter 409 whose cutoff frequency is the first frequency A, and a sample stage on which the sample is placed. In the plasma processing apparatus 400, a third filter 410, a first inductor L1, and a variable capacitor VC are arranged in series between the second filter 409 and the second electrode 402, a fourth filter 411 and a second inductor L2 are arranged in series between the second filter 409 and the second electrode 402 and are arranged in parallel with the third filter 410 and the first inductor L1, and the transmission path between the first filter 408 and the first electrode 401 is connected to the transmission path between the second filter 409 and the third filter 410. A specific description will be given below.

[0015] The plasma processing apparatus 400 includes a vacuum chamber 413, and a wafer (sample) is plasma-processed in the processing chamber within the vacuum chamber 413. The first electrode 401 and the second electrode 402 are disposed within the processing chamber. The plasma processing apparatus 400 also includes a member disposed on the outer periphery of a sample stage, with the first electrode 401 disposed within the sample stage and the second electrode 402 disposed within the member. For example, if the plasma processing apparatus is an ECR (Electron Cyclotron Resonance) etching processing apparatus, the first electrode 401 can be disposed within the sample stage on which the wafer (sample) is placed, and the second electrode 402 can be disposed within the member disposed on the outer periphery of the sample stage, in order to control the bias potential in the in-plane direction. The first electrode 401 can be a disk-shaped electrode, and the second electrode 402 can be a ring-shaped electrode surrounding the first electrode 401 (hereinafter also referred to as the "peripheral ring"), thereby forming a bias potential uniformly in the plane direction.

[0016] The first impedance matching device 405 performs impedance matching between the first high frequency power supply 403 and the first filter 408. The second impedance matching device 406 performs impedance matching between the second high frequency power supply 404 and the second filter 409. The first filter 408 and the third filter 410 have a cutoff frequency of B [Hz], and the second filter 409 and the fourth filter 411 have a cutoff frequency of A [Hz]. Note that A [Hz] is assumed to be smaller than B [Hz].

[0017] For convenience, the circuit configuration including the first filter 408, the second filter 409, the third filter 410, the fourth filter 411, the first inductor L1, the second inductor L2, and the variable capacitor VC is also referred to as a superposition branch section 407. Furthermore, for convenience, the circuit portion including the first inductor L1, the second inductor L2, and the variable capacitor VC is also referred to as a resonant circuit 412.

[0018] Explaining the flow of power in the circuit, the output of first impedance matching device 405 is input to first filter 408, and the output of second impedance matching device 406 is input to second filter 409. The output of first filter 408 branches, and one branched output is input to first electrode 401, while the other branched output is merged with the output of second filter 409. The merged output is branched and input to third filter 410 and fourth filter 411.

[0019] The output of the third filter 410 is input to the first inductor L1, and the output of the fourth filter 411 is input to the second inductor L2. The outputs of the first inductor L1 and the second inductor L2 join together and are input to the variable capacitor VC, and the output of the variable capacitor VC is input to the second electrode 402.

[0020] The first filter 408, the second filter 409, the third filter 410, and the fourth filter 411 are so-called band-stop filters that block specific frequency components while passing frequency components lower or wider than those frequency components without attenuation. The first inductor L1 and the second inductor L2 are, for example, coils. The capacitor C disposed between the first filter 408 and the first electrode 401 blocks the DC component flowing to the first electrode 401.

[0021] (Operation) Next, the operation of the plasma processing apparatus 400 will be described with reference to Fig. 5. Fig. 5 is a diagram schematically showing the frequency characteristics of the gain of the resonant circuit 412. Fig. 5(a) shows a hypothetical case where the resonant circuit 412 has the configuration of a conventional resonant circuit, and Fig. 5(b) shows a case where the resonant circuit 412 has the configuration of Fig. 4.

[0022] 1, the frequency characteristics of the gain of the resonant circuit 412 increase at the resonant frequency C, as shown in FIG. 5A. Meanwhile, the first inductor L1 corresponds to the first frequency A, and the second inductor L2 corresponds to the second frequency B. Specifically, if the resonant circuit 412 is an LC series circuit of the first inductor L1 and the variable capacitor VC, the resonant frequency is A [Hz].

[0023] Furthermore, if the resonant circuit 412 is an LC series circuit of the second inductor L2 and the variable capacitor VC, the resonant frequency will be B [Hz]. The high-frequency power output from the first high-frequency power supply 403 passes through the first filter 408 in the superposition branching section 407, then branches, and is applied to the first electrode 401 and the second electrode 402, respectively. That is, the voltage applied to the second electrode 402 is adjusted in the state of the resonant frequency C.

[0024] To explain the change in power in the circuit in order, high frequency power P output from first high frequency power supply 403 passes through first filter 408 in superimposed branching section 407, is branched, and is applied to first electrode 401 and second electrode 402. In the following description, the high frequency power flowing to first electrode 401 is designated as P1, and the high frequency power flowing to second electrode 402 is designated as P2.

[0025] Here, if the resonant circuit has a conventional configuration, the first high-frequency power supply 403 is set to output high-frequency power P having a frequency that satisfies the resonant frequency in Figure 5 (a), and power is applied to the second electrode 402.

[0026] In contrast, in the present disclosure, the high-frequency power P2 applied to the second electrode 402 passes through the third filter 410, and a portion of the power P22 branches off within the resonant circuit 412 and flows toward the fourth filter 411. The power P22 is then reflected by the fourth filter 411 and interferes with the power P21 applied to the second electrode 402. Due to the phase shift in the delay direction that occurs when the power passes through the second inductor L2 in the resonant circuit 412 and the phase shift in the advance direction that occurs due to reflection by the fourth filter 411, the gain of the high-frequency power applied to the second electrode 402 increases sharply on the frequency side lower than A [Hz] (e.g., region AL) and decreases sharply on the frequency side higher than A [Hz] (e.g., region AH), as shown in FIG. 5B. The resonant frequency C in FIG. 5 can be adjusted by changing the variable capacitor VC, and the resonant frequency C can be adjusted in an offset manner so that the regions AL and AH are shifted toward the lower or higher frequencies.

[0027] The above description also applies to the second high-frequency power supply 404, the second filter 409, the third filter 410, and the resonant circuit 412. Specifically, as shown in Fig. 5B, the gain of the high-frequency power increases sharply on the frequency side lower than B [Hz] (e.g., in the region BL) and decreases sharply on the frequency side higher than B [Hz] (e.g., in the region BH). The number of adjustable frequencies is not limited to two, and the number of adjustable frequencies can be increased by increasing the number of filters and coils in the resonant circuit 412.

[0028] In this way, it is possible to actively utilize the steep slope of the gain that is generated by the presence of the third filter 410 and the fourth filter 411. For example, by finely adjusting the resonant frequency of the resonant circuit 412 during discharge, it is possible to simultaneously control the high frequency output on the second electrode 402 side to be greater than the high frequency output on the first electrode 401 side for two or more frequencies.

[0029] As described above, according to the present disclosure, it is possible to control a plurality of high-frequency powers having different frequencies. For example, since it is possible to precisely control the power applied to the first electrode 401 and the power applied to the second electrode 402 according to the conditions, it is possible to control the plasma distribution in the surface direction and improve the in-surface uniformity of the etching process.

[0030] (Modification 1) Next, Modification 1 will be described with reference to Fig. 6. Modification 1 differs from the first embodiment in that the plasma processing apparatus uses capacitively coupled plasma (CCP) and applies power to a first upper electrode 604 and a second upper electrode 605. Fig. 6 is a diagram showing the configuration of the plasma processing apparatus of Modification 1. In the following description, descriptions of components that are the same as or equivalent to those in the first embodiment will be simplified or omitted.

[0031] The plasma processing apparatus 600 includes an antenna 619 facing a sample stage 601, and a second electrode (second upper electrode 605) is disposed within the antenna 619. Specifically, the plasma processing apparatus 600 includes a processing chamber formed within a vacuum chamber 606, which includes the sample stage 601, a lower electrode 602, a wafer 603, a first upper electrode 604, and a second upper electrode 605. The configuration for applying power to the first upper electrode 604 and the second upper electrode 605 is the same as that in the plasma processing apparatus 400 of the first embodiment. The first high-frequency power supply 609, the second high-frequency power supply 610, the first impedance matching box 611, the second impedance matching box 612, and the overlapping branching unit 613 in the plasma processing apparatus 600 correspond to the first high-frequency power supply 403, the second high-frequency power supply 404, the first impedance matching box 405, the second impedance matching box 406, and the overlapping branching unit 407 in the plasma processing apparatus 400 of the first embodiment, respectively.

[0032] Furthermore, the first filter 614, the second filter 615, the third filter 616, and the fourth filter 617 in the overlapping branching unit 613 correspond to the first filter 408, the second filter 409, the third filter 410, and the fourth filter 411 in the overlapping branching unit 407, respectively.

[0033] Furthermore, the first inductor L1, the second inductor L2, and the variable capacitor VC in the resonant circuit 618 correspond to the first inductor L1, the second inductor L2, and the variable capacitor VC in the resonant circuit 412, respectively.

[0034] The high frequency power supply 607 for attracting ions outputs high frequency power to the lower electrode 602. The impedance matching device 608 performs impedance matching for the output of the high frequency power for attracting ions.

[0035] (Actions and Effects) In the plasma processing apparatus 600, plasma is generated using a high-frequency electric field generated between the lower electrode 602 and the upper electrodes (first upper electrode 604 and second upper electrode 605), and plasma processing is performed on the wafer 603. Since the distribution of the plasma generated using the first upper electrode 604 can be controlled while the plasma is generated using the second upper electrode 605 and the antenna 619, a desired plasma distribution can be achieved. Furthermore, since multiple high-frequency powers with different frequencies can be controlled, the controllability of the etching shape can be improved compared to conventional CCP-type plasma processing apparatuses.

[0036] (Modification 2) Next, Modification 2 will be described with reference to Fig. 7. Modification 2 differs from the first embodiment in that the first electrode 702 and the second electrode 703 are electrodes of the same size and that the first electrode 702 and the second electrode 703 are disposed within a sample stage 701. Fig. 7 is a diagram showing the configuration of a plasma processing apparatus according to Modification 2. In the following description, the description of components that are the same as or equivalent to those in the first embodiment will be simplified or omitted.

[0037] The plasma processing apparatus 700 has a sample stage 701, a first electrode 702, and a second electrode 703 in a processing chamber formed in a vacuum chamber 714. Specifically, the plasma processing apparatus 700 has a configuration in which the first electrode 702 and the second electrode 703 are disposed within the sample stage 701. The configuration for applying power to the first electrode 702 and the second electrode 703 is the same as that in the plasma processing apparatus 400 of the first embodiment. The first high-frequency power supply 704, the second high-frequency power supply 705, the first impedance matching box 706, the second impedance matching box 707, and the overlapping branching unit 708 in the plasma processing apparatus 700 correspond to the first high-frequency power supply 403, the second high-frequency power supply 404, the first impedance matching box 405, the second impedance matching box 406, and the overlapping branching unit 407 in the plasma processing apparatus 400, respectively.

[0038] Furthermore, the first filter 709, the second filter 710, the third filter 711, and the fourth filter 712 in the overlapping branching section 708 correspond to the first filter 408, the second filter 409, the third filter 410, and the fourth filter 411 in the overlapping branching section 407 of the plasma processing apparatus 400 of the first embodiment, respectively.

[0039] Furthermore, the first inductor L1, the second inductor L2, and the variable capacitor VC in the resonant circuit 713 correspond to the first inductor L1, the second inductor L2, and the variable capacitor VC in the resonant circuit 412 of the plasma processing apparatus 400 of the first embodiment, respectively.

[0040] (Operations and Effects) The first electrode 702 and the second electrode 703 are electrodes of the same size, and have, for example, a semicircular shape or a shape obtained by dividing a circle. It is possible to control the plasma distribution while controlling multiple high-frequency powers with different frequencies. According to Modification 2, it is possible to improve the uniformity of the in-plane distribution, regardless of the shape of the electrodes.

[0041] (Modification 3) Next, Modification 3 will be described with reference to Fig. 8. Modification 3 differs from the first embodiment in that the high-frequency power supply can output high-frequency power at a plurality of frequencies. Fig. 8 is a diagram showing the configuration of a plasma processing apparatus 800 according to Modification 3. In the following description, the description of components that are the same as or equivalent to those in the first embodiment will be simplified or omitted.

[0042] The plasma processing apparatus 800 includes a processing chamber in which a sample is subjected to plasma processing, and a plurality of high frequency power sources 803 that supply high frequency power to a first electrode 801 and a second electrode 802. １ From 803 ｎ and a sample stage on which a sample is placed. When n is an integer of 2 or more, the nth high frequency power supply 803 ｎ is the nth impedance matching device 804 ｎ and the nth filter 805 ｎ High frequency power is supplied to the first electrode 801 via the n-th impedance matching device 804 ｎ , nth filter 805 ｎ , 2nth filter 806 ２ｎ , the nth inductor L ｎ And high frequency power is supplied to the second electrode 802 via a variable capacitor VC.

[0043] Also, the 2nth filter 806 ２ｎ and the n-th inductor L ｎ is the (2n-1)th filter 806 ２ｎ－１ and the (n-1)th inductor L ｎ－１ In addition, the n-th filter 805 ｎ and the 2nth filter 806 ２ｎ is the nth frequency f ｎ is the pass frequency. Note that, although a case where n high frequency power sources 803, n impedance matching devices 804, n filters 805, n filters 806, and n inductors are included will be described, the present disclosure is not limited to this case. The present disclosure can also be applied to a case where the number of devices is n or more.

[0044] To specifically describe the configuration of the plasma processing apparatus 800, the plasma processing apparatus 800 includes a vacuum chamber 809, and a wafer (sample) is plasma-processed in a processing chamber within the vacuum chamber 809. A first electrode 801 and a second electrode 802 are disposed within the processing chamber. The plasma processing apparatus 800 further includes a member disposed on the outer periphery of a sample stage, with the first electrode 801 disposed within the sample stage and the second electrode 802 disposed within the member. The configuration for applying power to the first electrode 801 and the second electrode 802 is similar to the configuration in the plasma processing apparatus 400 of the first embodiment.

[0045] Multiple high frequency power sources 803 １ From 803 ｎ The mth (m is an integer from 1 to n) high frequency power supply 803 ｍ is the frequency f ｍ The mth impedance matching device 804 outputs a high frequency power of ｍ is the mth high frequency power supply 803 ｍ and the mth filter 805 ｍ Impedance matching is performed between

[0046] nth filter 805 ｎ and the 2nth filter 806 ２ｎ The first filter 805 is a bandpass filter that passes a specific frequency component while blocking frequency components lower or wider than the specific frequency component. １ and the (n+1)th filter 806 ｎ＋１ The passing frequency of １ , second filter 805 ２ and the (n+2)th 806 ｎ＋２ The passing frequency of ２ to n-th filter 805 ｎ and the 2nth filter 806 ２ｎ The passing frequency of ｎ The (n+1)th filter 806 ｎ＋１ to the 2n-th filter 806 ２Ｍ The inductor L １ , inductor L ２ to inductor L ｎare connected, and each inductor corresponds to the pass frequency of the filter to which it is connected. １ From L ｎ The output of is connected to a variable capacitor VC. ０ is the largest, and f １ , ..., f ｎ It is also possible to set it so that it becomes smaller as

[0047] In addition, the filter 805 １ From 805 ｎ , filter 806 ｎ＋１ From 806 ２ｎ , resonant circuit 807, capacitor C, inductor L １ From L ｎ , the circuit configuration including the variable capacitor VC is also referred to as a superposition branch section 808 for convenience. １ From L ｎ The circuit configuration including the variable capacitor VC is also called a resonant circuit 807.

[0048] (Function and Effect) The gain of the resonant circuit 807 is １ , f ２ ~f ｎ The frequency of the high frequency power output by the high frequency power source 803 is f １ , f ２ ~f ｎ By selecting one of these frequencies, it becomes possible to utilize a large gain and easily control the power applied to the second electrode 802. Even if the frequency of the high frequency power is limited, it becomes possible to utilize the gain characteristics using the resonant circuit 807 by adjusting the frequency of the high frequency power output from the high frequency power supply.

[0049] (Modification 4) Next, Modification 4 will be described with reference to Fig. 9. Modification 4 differs from Modification 2 in that the configuration of the resonant circuit 713 in Modification 2 is changed. Fig. 9 is a diagram showing the configuration of a plasma processing apparatus 900 of Modification 4. In the following description, the description of components that are the same as or equivalent to those in the first embodiment described above will be simplified or omitted.

[0050] The plasma processing apparatus 900 includes a processing chamber in which a sample is plasma-processed, a first high-frequency power supply 904 that supplies high-frequency power of a first frequency A to a first electrode 902 via a first impedance matching device 906 and a first filter 909 having a cutoff frequency of a second frequency B, a second high-frequency power supply 905 that supplies second high-frequency power of a second frequency B to a second electrode 903 via a second impedance matching device 907 and a second filter 910 having a cutoff frequency of the first frequency A, and a sample stage 901 on which the sample is placed. In the plasma processing apparatus 900, a third filter 911, a first capacitor C1, and a variable inductor VL are arranged in series between the second filter 910 and the second electrode 903, a fourth filter 912 and a second capacitor C2 are arranged in series between the second filter 910 and the second electrode 903 and in parallel with the third filter 911 and the first capacitor C1, and the transmission path between the first filter 909 and the first electrode 902 is connected to the transmission path between the second filter 910 and the third filter 911. A specific description will be given below.

[0051] The plasma processing apparatus 900 includes a sample stage 901, a first electrode 902, and a second electrode 903 in a processing chamber formed within a vacuum chamber 914. Specifically, the plasma processing apparatus 900 has a configuration in which the first electrode 902 and the second electrode 903 are disposed within the sample stage 901. The configuration for applying power to the first electrode 902 and the second electrode 903 is the same as that in the plasma processing apparatus 400 of the first embodiment. A first impedance matching box 906 performs impedance matching between the first high-frequency power supply 403 and the first filter 408. A second impedance matching box 406 performs impedance matching between the second high-frequency power supply 404 and the second filter 409. The first filter 408 and the third filter 410 have a cutoff frequency of B [Hz], and the second filter 409 and the fourth filter 411 have a cutoff frequency of A [Hz]. Note that A [Hz] is smaller than B [Hz].

[0052] Furthermore, the first filter 909, the second filter 910, the third filter 911, and the fourth filter 912 in the overlapping branching section 908 correspond to the first filter 408, the second filter 409, the third filter 410, and the fourth filter 411 in the overlapping branching section 407 in the plasma processing apparatus 400 of the first embodiment, respectively.

[0053] The resonant circuit 913 includes a first capacitor C1 and a second capacitor C2, which are fixed capacitors, and a variable inductor VL. In the resonant circuit 913, an LC series circuit of the first capacitor C1 and the variable inductor VL, and an LC series circuit of the second capacitor C2 and the variable inductor VL can be virtually formed. By adjusting the values ​​of the first capacitor C1, the second capacitor C2, and the variable inductor VL, two resonance points can be set in the gain frequency characteristics of the resonant circuit 913.

[0054] (Operations and Effects) In addition to forming a resonant circuit using a combination of a fixed inductor and a variable capacitor, a resonant circuit can be formed using a combination of a fixed capacitor and a variable inductor, and the gain can be amplified.

[0055] (Modification 5) Next, Modification 5 will be described with reference to FIGS. 10 and 11 . Modification 5 differs from the first embodiment in that the cutoff frequency of first filter 1008 is different from the cutoff frequency of third filter 1010 and the cutoff frequency of second filter 1009 is different from the cutoff frequency of fourth filter 1011. FIG. 10 is a diagram showing the configuration of a plasma processing apparatus 1000 according to Modification 5. FIG. 11 is a diagram showing a schematic diagram of the gain-frequency characteristics of resonant circuit 1012. In the following description, descriptions of components that are the same as or equivalent to those in the first embodiment will be simplified or omitted.

[0056] The plasma processing apparatus 1000 is, for example, a plasma etching apparatus, and includes a bias application system including a first high-frequency power supply 1003 that outputs a high-frequency signal at an oscillation frequency of A [Hz], a second high-frequency power supply 1004 that outputs a high-frequency signal at B [Hz], a first impedance matching device 1005 that performs impedance matching for the high-frequency signal at A [Hz], a second impedance matching device 1006 that performs impedance matching for the high-frequency signal at B [Hz], and a superposition / branching unit 1007 that superimposes multiple high-frequency signals and then branches the superimposed signals to an electrode (first electrode) 1001 and an outer ring (second electrode) 1002. The superposition branching unit 1007 includes a first filter 1008 having a cutoff frequency of B1 [Hz], a second filter 1009 having a cutoff frequency of A1 [Hz], a third filter 1010 having a cutoff frequency of B2 [Hz], a fourth filter 1011 having a cutoff frequency of A2 [Hz], and a resonant circuit 1012 having a resonant frequency of α [Hz].

[0057] The relationships between the cutoff frequency and resonant frequency of each circuit are A = A1 < A2 < α and B = B1 < B2 < α. In other words, the cutoff frequency A1 of the second filter 1009 is lower than the cutoff frequency A2 of the fourth filter 1011, which is lower than the resonant frequency α of the resonant circuit 1012 formed by the first inductor L1, the second inductor L2, and the variable capacitor VC. The cutoff frequency B1 of the first filter 1008 is lower than the cutoff frequency B2 of the third filter 1010, which is lower than the resonant frequency α of the resonant circuit 1012.

[0058] The vacuum chamber 1013, the electrode 1001, and the outer ring 1002 correspond to the vacuum chamber 413, the first electrode 401, and the second electrode 402, respectively, in the plasma processing apparatus 400 of the first embodiment. The overlapping branching portion 1007 and the resonant circuit 1012 correspond to the overlapping branching portion 407 and the resonant circuit 412, respectively, in the plasma processing apparatus 400 of the first embodiment.

[0059] (Operation) Next, the operation of the plasma processing apparatus 1000 will be described with reference to Fig. 11. Fig. 11 is a diagram schematically showing the frequency characteristics of the gain of the resonant circuit 1012.

[0060] In the plasma processing apparatus 1000, high-frequency power P output from the first high-frequency power supply 1003 passes through the first filter 1008, the third filter 1010, and the resonant circuit 1012 and is applied to the outer ring 1002, but a portion of the power branches off at the resonant circuit 1012 and flows toward the fourth filter 1011. The power P2 that flows toward the fourth filter 1011 is then reflected by the fourth filter 1011 and interferes with the power applied to the outer ring 1002. In FIG. 11 , the power flowing to the electrode 1001 is designated P1, and the power flowing toward the fourth filter 1011 is designated P2. Of the power P2, the power flowing to the fourth filter 1011 is designated P22, and the power flowing to the outer ring 1002 is designated P21.

[0061] In this case, the power that has undergone a phase shift in the lag direction when passing through the second inductor L2 in the resonant circuit 1012 and the power that has undergone a phase shift in the lead direction when reflected by the fourth filter 1011 are superimposed on the original high-frequency power, forming a steep slope as the gain-frequency characteristic at frequency A [Hz] (e.g., region AL1). By actively utilizing this slope, for example, by finely adjusting the resonant frequency α of the resonant circuit 1012 during discharge in the processing chamber of the vacuum chamber 1013, it is possible to greatly control the high-frequency output on the outer ring 1002 side relative to the high-frequency output on the electrode 1001 side. In FIG. 11 , of the power P22, the power that has undergone a phase shift in the lag direction when passing through the second inductor L2 is designated P22d, and the power that has undergone a phase shift in the lead direction after being reflected by the fourth filter 1011 is designated P22a. The power P22d and the power P22a are superimposed on the power P21.

[0062] Furthermore, a steep increase in gain occurs in region AL1, while a steep decrease in gain occurs in region AL2, which is a region including frequency A2. Region AL1 is located on the higher frequency side compared to region AL in the first embodiment. This is because the cutoff frequency A2 of the fourth filter 1011 is higher than the cutoff frequency A1 of the second filter 1009. Compared to the first embodiment, a steep change in gain occurs on the higher frequency side than frequency A [Hz], which allows for more flexible control of the high-frequency output on the outer ring 1002 side.

[0063] The above description can be similarly applied to the relationship between the second high-frequency power supply 1004, the second filter 1009, the third filter 1010, and the resonant circuit 1012. For example, as shown in region BL1 in Fig. 11 , it is possible to utilize the steep slope of the gain at frequency B [Hz]. Furthermore, region BH1 occurs on the higher frequency side than region BH in the first embodiment, so that the high-frequency output on the outer ring 1002 side can be controlled more flexibly.

[0064] (Functions and Effects) By making the cutoff frequency of the third filter 1010 higher than the cutoff frequency of the first filter 1008 and by making the cutoff frequency of the fourth filter 1011 higher than the cutoff frequency of the second filter 1009, it is possible to expand the range in which the gain frequency characteristics change sharply, thereby enabling more flexible control of the high frequency output.

[0065] (Variation 6) Next, Variation 6 will be described with reference to Fig. 12. Variation 6 shows a case where the filter frequency relationship in Variation 5 is applied to the configuration in Variation 4. Fig. 12 is a diagram showing the configuration of a plasma processing apparatus according to Variation 6. In the following description, the description of components that are the same as or equivalent to those in the first embodiment or Variation 5 described above will be simplified or omitted.

[0066] The plasma processing apparatus 1100 is, for example, a plasma etching apparatus. The plasma processing apparatus 1100 has a bias application system including a first high-frequency power supply 1104 that generates a high-frequency output at an oscillation frequency A [Hz], a second high-frequency power supply 1105 that generates a high-frequency output at B [Hz], a first impedance matching device 1106 that performs impedance matching for the high-frequency output at A [Hz], a second impedance matching device 1107 that performs impedance matching for the high-frequency output at B [Hz], and a superposition branching unit 1108 that superimposes multiple high-frequency outputs and then branches the superimposed output to a first electrode 1102 and a second electrode 1103. The superposition branching unit 1108 includes a first filter 1109 with a cutoff frequency of B1 [Hz], a second filter 1110 with a cutoff frequency of A1 [Hz], a third filter 1111 with a cutoff frequency of B2 [Hz], a fourth filter 1112 with a cutoff frequency of A2 [Hz], and a resonant circuit 1113 with a resonant frequency of α1 [Hz].

[0067] The relationships between the cutoff frequency and resonant frequency of each circuit are A = A1 < A2 < α1 and B = B1 < B2 < α1. In other words, the cutoff frequency A1 of the second filter 1110 is lower than the cutoff frequency A2 of the fourth filter 1112, which in turn is lower than the resonant frequency α1 of the resonant circuit 1113 formed by the first capacitor C1, the second capacitor C2, and the variable inductor VL. The cutoff frequency B1 of the first filter 1109 is lower than the cutoff frequency B2 of the third filter 1111, which in turn is lower than the resonant frequency α1 of the resonant circuit 1113.

[0068] The sample stage 1101, the vacuum chamber 1114, the first electrode 1102, and the second electrode 1103 correspond to the sample stage 901, the vacuum chamber 914, the first electrode 902, and the second electrode 903, respectively, in the plasma processing apparatus 900 of Modification 4. The overlapping branching portion 1108 and the resonant circuit 1113 correspond to the overlapping branching portion 908 and the resonant circuit 913, respectively, in the plasma processing apparatus 900 of Modification 4.

[0069] By adjusting the values ​​of the first capacitor C1, the second capacitor C2, and the variable inductor VL, it is possible to set two resonance points in the gain-frequency characteristics of the resonant circuit 913. Furthermore, as in the case of the fifth modification, by making the cutoff frequency of the third filter 1111 higher than the cutoff frequency of the first filter 1109 and by making the cutoff frequency of the fourth filter 1112 higher than the cutoff frequency of the second filter 1110, it is possible to expand the range in which the gain-frequency characteristics change sharply.

[0070] (Operations and Effects) In addition to forming a resonant circuit using a combination of a fixed inductor and a variable capacitor, a resonant circuit can be formed using a combination of a fixed capacitor and a variable inductor, and the gain can be amplified.

[0071] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention.

[0072] The following are some non-limiting aspects of the present invention. (Aspect 1) A plasma processing apparatus comprising: a processing chamber for plasma processing a sample; a first high-frequency power supply that supplies high-frequency power of a first frequency to a first electrode via a first impedance matcher and a first filter having a cutoff frequency of a second frequency; a second high-frequency power supply that supplies second high-frequency power of a second frequency to a second electrode via a second impedance matcher and a second filter having a cutoff frequency of the first frequency; and a sample stage on which the sample is placed, wherein a third filter, a first inductor, and a variable capacitor are arranged in series between the second filter and the second electrode; a fourth filter and a second inductor are arranged in series between the second filter and the second electrode and in parallel with the third filter and the first inductor; and a transmission line between the first filter and the first electrode connected to a transmission line between the second filter and the third filter. (Aspect 2) The plasma processing apparatus according to Aspect 1, wherein the first frequency is lower than the second frequency. (Aspect 3) The plasma processing apparatus according to Aspect 1 or 2, further comprising a member arranged on the outer periphery of the sample stage, wherein the first electrode is arranged within the sample stage, and the second electrode is arranged within the member. (Aspect 4) The plasma processing apparatus according to any one of Aspects 1 to 3, further comprising an antenna facing the sample stage, wherein the second electrode is arranged within the antenna. (Aspect 5) The plasma processing apparatus according to any one of Aspects 1 to 4, further comprising the first electrode and the second electrode arranged within the sample stage.(Aspect 6) A plasma processing apparatus comprising: a processing chamber in which a sample is plasma-processed; a plurality of radio frequency power sources that supply radio frequency power to a first electrode and a second electrode; and a sample stage on which the sample is placed; wherein, where n is an integer of 2 or greater, an nth radio frequency power source supplies radio frequency power to the first electrode via an nth impedance matching device and an nth filter, and supplies radio frequency power to the second electrode via the nth impedance matching device, the nth filter, a 2nth filter, an nth inductor, and a variable capacitor; the 2nth filter and the nth inductor are arranged in parallel with the (2n-1)th filter and the (n-1)th inductor; and the nth filter and the 2nth filter are filters that have the nth frequency as their pass frequency. (Aspect 7) A plasma processing apparatus comprising: a processing chamber in which a sample is plasma processed; a first high frequency power supply that supplies high frequency power of a first frequency to a first electrode via a first impedance matching device and a first filter having a cutoff frequency of a second frequency; a second high frequency power supply that supplies second high frequency power of a second frequency to a second electrode via a second impedance matching device and a second filter having a cutoff frequency of the first frequency; and a sample stage on which the sample is placed, characterized in that a third filter, a first capacitor, and a variable inductor are arranged in series between the second filter and the second electrode; a fourth filter and a second capacitor are arranged in series between the second filter and the second electrode and in parallel with the third filter and the first capacitor; and a transmission path between the first filter and the first electrode is connected to a transmission path between the second filter and the third filter.(Aspect 8) The plasma processing apparatus according to any one of Aspects 1 to 7, wherein the cutoff frequency of the second filter is lower than the cutoff frequency of the fourth filter, the cutoff frequency of the fourth filter is lower than the resonant frequency of a resonant circuit formed by the first inductor, the second inductor, and the variable capacitor, the cutoff frequency of the first filter is lower than the cutoff frequency of the third filter, and the cutoff frequency of the third filter is lower than the resonant frequency of the resonant circuit. (Aspect 9) The plasma processing apparatus according to any one of Aspects 1 to 7, wherein the cutoff frequency of the second filter is lower than the cutoff frequency of the fourth filter, the cutoff frequency of the fourth filter is lower than the resonant frequency of a resonant circuit formed by the first capacitor, the second capacitor, and the variable inductor, the cutoff frequency of the first filter is lower than the cutoff frequency of the third filter, and the cutoff frequency of the third filter is lower than the resonant frequency of the resonant circuit.

[0073] 400: plasma processing apparatus, 401: first electrode, 402: second electrode, 403: first high frequency power supply, 404: second high frequency power supply, 405: first impedance matching box, 406: second impedance matching box, 407: overlapping branch section, 408: first filter, 409: second filter, 410: third filter, 411: fourth filter, 412: resonant circuit, 413: vacuum chamber, L1: first inductor, L2: second inductor, VC: variable capacitor, 600: plasma processing apparatus, 601: sample stage, 602: lower electrode, 603: wafer, 604: first upper electrode, 605: second upper electrode, 606: vacuum chamber, 607: high frequency power supply for ion attraction, 608: impedance matching box, 609: first high frequency power supply, 610: second high frequency power supply, 611: first impedance matching box, 612: second impedance matching box, 613: overlapping branch section, 614: first filter, 615: second filter, 616: third filter, 617: fourth filter, 618: resonant circuit, 619: antenna, 700: plasma processing apparatus, 701: sample stage, 702: first electrode, 703: second electrode, 704: first high frequency power supply, 705: second high frequency power supply, 706: first impedance matching box, 707: second impedance matching box, 708: overlapping branch section, 709: first filter, 710: second filter, 711: third filter, 712: fourth filter, 713: resonant circuit, 714: vacuum chamber, 800: plasma processing apparatus, 801: first electrode, 802: second electrode, 803 １ ~803 ｎ :High frequency power supply, 804 １ ~804 ｎ : Impedance matching box, 805 １ ~805 ｎ , 806 ｎ＋１ ~806 ２ｎ : filter, 807: resonant circuit, 808: superposition branching section, 809: vacuum chamber, L １ ~L ｎ: inductor, 900: plasma processing apparatus, 901: sample stage, 902: first electrode, 903: second electrode, 904: first high frequency power supply, 905: second high frequency power supply, 906: first impedance matching box, 907: second impedance matching box, 908: overlapping branch section, 909: first filter, 910: second filter, 911: third filter, 912: fourth filter, 913: resonant circuit, 914: vacuum chamber, C1: first capacitor, C2: second capacitor, 1000: plasma processing apparatus, 1001: electrode (first electrode), 1002: outer ring (second electrode), 1003: first high frequency power supply, 1004: second high frequency power supply, 1005: first impedance matching box, 1006: second impedance matching box, 1007: overlapping branch section, 1008: first filter, 1009: second filter, 1010: third filter, 1011: fourth filter, 1012: resonant circuit, 1013: vacuum chamber, C1: first capacitor, C2: second capacitor, VL: variable inductor, 1100: plasma processing apparatus, 1101: sample stage, 1102: first electrode, 1103: second electrode, 1104: first high frequency power supply, 1105: second high frequency power supply, 1106: first impedance matching box, 1107: second impedance matching box, 1108: overlapping branch section, 1109: first filter, 1110: second filter, 1111: third filter, 1112: fourth filter, 1113: resonant circuit, 1114: vacuum chamber

Claims

1. A plasma processing apparatus comprising: a processing chamber in which a sample is plasma-processed; a first high-frequency power supply that supplies high-frequency power of a first frequency to a first electrode via a first impedance matcher and a first filter having a cutoff frequency of a second frequency; a second high-frequency power supply that supplies second high-frequency power of a second frequency to a second electrode via a second impedance matcher and a second filter having a cutoff frequency of the first frequency; and a sample stage on which the sample is placed, characterized in that a third filter, a first inductor, and a variable capacitor are arranged in series between the second filter and the second electrode; a fourth filter and a second inductor are arranged in series between the second filter and the second electrode and in parallel with the third filter and the first inductor; and a transmission line between the first filter and the first electrode is connected to a transmission line between the second filter and the third filter.

2. A plasma processing apparatus according to claim 1, wherein the first frequency is lower than the second frequency.

3. A plasma processing apparatus according to claim 1, further comprising a member arranged on the outer periphery of the sample stage, wherein the first electrode is arranged within the sample stage, and the second electrode is arranged within the member.

4. A plasma processing apparatus according to claim 1, further comprising an antenna facing said sample stage, said second electrode being disposed within said antenna.

5. A plasma processing apparatus according to claim 1, wherein the first electrode and the second electrode are disposed within the sample stage.

6. A plasma processing apparatus comprising a processing chamber in which a sample is plasma-processed, a plurality of high frequency power supplies that supply high frequency power to a first electrode and a second electrode, and a sample stage on which the sample is placed, wherein, where n is an integer of 2 or greater, the nth high frequency power supply supplies high frequency power to the first electrode via the nth impedance matching device and the nth filter, and supplies high frequency power to the second electrode via the nth impedance matching device, the nth filter, a 2nth filter, an nth inductor, and a variable capacitor, the 2nth filter and the nth inductor are arranged in parallel with the (2n-1)th filter and the (n-1)th inductor, and the nth filter and the 2nth filter are filters that pass the nth frequency.

7. A plasma processing apparatus comprising: a processing chamber in which a sample is plasma-processed; a first high-frequency power supply that supplies high-frequency power of a first frequency to a first electrode via a first impedance matcher and a first filter having a cutoff frequency of a second frequency; a second high-frequency power supply that supplies second high-frequency power of a second frequency to a second electrode via a second impedance matcher and a second filter having a cutoff frequency of the first frequency; and a sample stage on which the sample is placed, characterized in that a third filter, a first capacitor, and a variable inductor are arranged in series between the second filter and the second electrode; a fourth filter and a second capacitor are arranged in series between the second filter and the second electrode and in parallel with the third filter and the first capacitor; and a transmission line between the first filter and the first electrode is connected to a transmission line between the second filter and the third filter.

8. A plasma processing apparatus according to claim 1, wherein the cutoff frequency of the second filter is lower than the cutoff frequency of the fourth filter, the cutoff frequency of the fourth filter is lower than the resonant frequency of a resonant circuit formed by the first inductor, the second inductor and the variable capacitor, the cutoff frequency of the first filter is lower than the cutoff frequency of the third filter, and the cutoff frequency of the third filter is lower than the resonant frequency of the resonant circuit.

9. A plasma processing apparatus according to claim 7, wherein the cutoff frequency of the second filter is lower than the cutoff frequency of the fourth filter, the cutoff frequency of the fourth filter is lower than the resonant frequency of a resonant circuit formed by the first capacitor, the second capacitor and the variable inductor, the cutoff frequency of the first filter is lower than the cutoff frequency of the third filter, and the cutoff frequency of the third filter is lower than the resonant frequency of the resonant circuit.

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