Radio frequency assembly with plasma processing device

Abstract

The utility model discloses a kind of radio frequency assembly and plasma processing equipment.Radio frequency assembly includes first radio frequency coil, second radio frequency coil, first filter and second filter.First radio frequency coil has the first feed-in end of access first frequency radio frequency signal and the first ground end grounded through first filter, second radio frequency coil has the second feed-in end of access second frequency radio frequency signal and the second ground end grounded through second filter.First filter allows first frequency to pass and suppress second frequency, and second filter allows second frequency to pass and suppress first frequency.Plasma processing equipment includes process cavity and dielectric window, and radio frequency assembly is located outside dielectric window to excite plasma in process cavity.The structure is conducive to blocking different frequency radio frequency current through ground path mutual streaming, reduce the cross coupling of radio frequency current between multi-frequency coil.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor plasma processing equipment technology, specifically to a radio frequency component and plasma processing equipment. Background Technology

[0002] Inductively coupled or transformer-coupled plasma processing equipment couples radio frequency (RF) energy to the process cavity via RF coils to excite and sustain the plasma. Some processes require the simultaneous application of RF power at different frequencies to control plasma density and ion energy separately; therefore, multiple RF coils operating at different frequencies are employed. In known multi-frequency coil structures, the grounding terminals of each coil are directly connected to ground. When two coils of different frequencies are arranged adjacent to each other, the RF current of one coil can be induced to the other coil through electromagnetic coupling between the coils, and then flows into the common ground plane via the grounding terminal of the other coil, forming cross-coupling of the RF current. This cross-coupling prevents the independent adjustment of the RF power at each frequency, leading to a decrease in the accuracy of plasma parameter control.

[0003] Another approach involves connecting a filter in series at the feed end of the RF coil, attempting to suppress interference between different frequencies through the filter's frequency selectivity. However, the feed end is a high-potential RF terminal, requiring the filter to withstand high RF voltages, thus placing high demands on component voltage withstand and power capacity. Furthermore, the filter, connected in series between the RF source and the coil, alters the feed end impedance, affecting impedance matching between the RF source and the coil. More critically, cross-coupled RF currents primarily flow through the common ground path, and the feed end filter cannot directly block this cross-current in the ground path. Another frequency, after being induced into the coil through electromagnetic coupling, can still flow into the common ground through the ground end. Utility Model Content

[0004] The technical problem to be solved by this utility model is: to address the shortcomings of the feed-end filtering affecting impedance matching and the inability to directly block cross-current in the grounding path, a radio frequency component and plasma processing equipment are provided to achieve frequency-selective grounding at the grounding end, so as to reduce the cross-coupling of radio frequency current between coils of different frequencies.

[0005] To solve the above-mentioned technical problems, the technical solution of this utility model is as follows:

[0006] A radio frequency (RF) component includes two independent RF coils. A first RF coil has a first feed terminal and a first ground terminal, the first feed terminal being used to receive an RF signal of a first frequency. A second RF coil has a second feed terminal and a second ground terminal, the second feed terminal being used to receive an RF signal of a second frequency. A first filter is connected in series between the first ground terminal and ground, and a second filter is connected in series between the second ground terminal and ground. The first filter allows the RF signal of the first frequency to pass through and be grounded, while suppressing the RF signal of the second frequency; the second filter allows the RF signal of the second frequency to pass through and be grounded, while suppressing the RF signal of the first frequency.

[0007] In some embodiments, the first filter includes a band-pass filter, a low-pass filter, or a high-pass filter, and the second filter includes a band-pass filter, a low-pass filter, or a high-pass filter.

[0008] In some embodiments, both the first RF coil and the second RF coil are planar spiral coils, with the second RF coil located inside the first RF coil, and the two are arranged in a nested configuration.

[0009] In some embodiments, the first radio frequency coil and the second radio frequency coil are arranged concentrically.

[0010] In some embodiments, the first filter and the second filter each include an LC resonant network.

[0011] In some embodiments, the LC resonant network includes a series inductor and a series capacitor connected in series between the corresponding ground terminal and ground, the series inductor and the series capacitor being configured to resonate in series at the operating frequency of the corresponding radio frequency coil.

[0012] In some embodiments, the first filter includes a first series inductor and a first series capacitor connected in series between the first ground terminal and ground, and the second filter includes a second series inductor and a second series capacitor connected in series between the second ground terminal and ground. The first frequency is less than the second frequency, and the product of the inductance value of the first series inductor and the capacitance value of the first series capacitor is greater than the product of the inductance value of the second series inductor and the capacitance value of the second series capacitor.

[0013] In some embodiments, the LC resonant network further includes a parallel resonant branch connected in series with the series inductor and the series capacitor. The parallel resonant branch includes a notch inductor and a notch capacitor connected in parallel with each other. The parallel resonant branch is configured to resonate in parallel with the operating frequency of another RF coil.

[0014] In some embodiments, the series inductor and the series capacitor are connected in series between the ground terminal and the intermediate node. The intermediate node is grounded through a notch inductor and a notch capacitor connected in parallel. The notch inductor and the notch capacitor are configured to resonate in parallel at the operating frequency of another RF coil. The intermediate node is also grounded through an additional series inductor and an additional series capacitor. The additional series inductor and the additional series capacitor are configured to resonate in series at the operating frequency of the corresponding RF coil.

[0015] In some embodiments, the first frequency is lower than the second frequency, the first filter is a low-pass filter, the second filter is a high-pass filter, and the cutoff frequency of the low-pass filter and the cutoff frequency of the high-pass filter are both between the first frequency and the second frequency.

[0016] In some embodiments, the first feed terminal is electrically connected to a first radio frequency source, the second feed terminal is electrically connected to a second radio frequency source, the first radio frequency source outputs a first frequency radio frequency signal, and the second radio frequency source outputs a second frequency radio frequency signal.

[0017] This utility model also provides a plasma processing device, including a process cavity having a dielectric window, and further including the aforementioned radio frequency component, the radio frequency component being disposed outside the dielectric window, and radio frequency energy being coupled into the process cavity through the dielectric window to excite plasma.

[0018] This invention connects a filter in series between the grounding terminal of each RF coil and ground. The filter has a low impedance to the operating frequency of the coil itself but a high impedance to the operating frequencies of other coils. This prevents the RF current induced by electromagnetic coupling from other coils from flowing into the common ground plane through the grounding terminal. This helps to block the path of cross-flow of RF currents of different frequencies through the grounding path and reduces the cross-coupling of RF currents between multi-frequency coils.

[0019] Compared to a scheme that connects a filter in series at the feed end, this invention places the filter between the ground terminal and ground, directly acting on the common ground path of the cross-coupled current, thus blocking crosstalk more directly. Simultaneously, the filter is not connected in series between the RF source and the coil, thus not changing the feed end impedance and avoiding interference with impedance matching between the RF source and the coil. Furthermore, the ground end potential is lower than the feed end potential, resulting in a lower RF voltage that the filter withstands, which helps reduce component withstand voltage requirements and improves operational reliability under high-power conditions. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of a radio frequency component according to an embodiment.

[0021] Figure 2 This is a circuit topology diagram of a filter according to one embodiment.

[0022] Figure 3 This is a circuit topology diagram of a filter according to another embodiment.

[0023] Figure 4 This is a circuit topology diagram for pairing a low-pass filter with a high-pass filter.

[0024] Figure 5 This is a circuit topology diagram of a filter according to yet another embodiment.

[0025] Figure 6 This is a schematic diagram of the plasma processing equipment.

[0026] Explanation of markings in the diagram

[0027] 100-RF components,

[0028] 110 - First RF coil, 111 - First feed-in terminal, 112 - First ground terminal.

[0029] 120 - Second RF coil, 121 - Second feed terminal, 122 - Second ground terminal

[0030] 130 - First filter, 131 - First series inductor, 132 - First series capacitor, 133 - First notch inductor, 134 - First notch capacitor, 135 - First low-pass inductor, 136 - First additional series inductor, 137 - First additional series capacitor.

[0031] 140 - Second filter, 150 - First RF source, 160 - Second RF source

[0032] 200 - Plasma processing equipment, 210 - Process chamber, 211 - Base, 220 - Dielectric window. Detailed Implementation

[0033] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0034] like Figure 1 As shown, the radio frequency component 100 includes a first radio frequency coil 110, a second radio frequency coil 120, a first filter 130, and a second filter 140.

[0035] The first radio frequency coil 110 has a first feed terminal 111 and a first ground terminal 112. The first feed terminal 111 is used to receive a radio frequency signal of a first frequency. A first filter 130 is connected in series between the first ground terminal 112 and ground, and is configured to allow the radio frequency signal of the first frequency to pass through and suppress the radio frequency signal of the second frequency.

[0036] The second RF coil 120 has a second feed terminal 121 and a second ground terminal 122. The second feed terminal 121 is used to receive a second frequency RF signal. The second filter 140 is connected in series between the second ground terminal 122 and ground, and is configured to allow the second frequency RF signal to pass through and suppress the first frequency RF signal.

[0037] The first frequency and the second frequency are not equal. By connecting a filter with frequency selectivity in series between the ground terminal of each RF coil and ground, the RF current induced by electromagnetic coupling from other coils cannot flow into the common ground plane through the ground terminal, thereby blocking the path for RF currents of different frequencies to cross-flow through the grounding path.

[0038] In one embodiment, the first filter 130 includes a bandpass filter, a low-pass filter, or a high-pass filter, and the second filter 140 includes a bandpass filter, a low-pass filter, or a high-pass filter. The first filter 130 and the second filter 140 can be of the same or different types, as long as their passband covers the operating frequency of the corresponding RF coil and their stopband covers the operating frequency of the other RF coil.

[0039] In one embodiment, the first filter 130 and the second filter 140 are bandpass filters. The passband center frequency of the bandpass filter is configured to be equal to the operating frequency of the corresponding RF coil, so that the operating frequency of the corresponding RF coil is within the passband and can be successfully grounded, while the operating frequency of the other RF coil is within the stopband and is suppressed, making it difficult to ground. The bandpass filter can be constructed from an LC series resonant network, utilizing the frequency selectivity characteristic of series resonance—low impedance at the resonant frequency and high impedance at deviations from the resonant frequency—to achieve frequency-selective grounding.

[0040] In one embodiment, both the first RF coil 110 and the second RF coil 120 are planar spiral coils, with the second RF coil 120 located inside the first RF coil 110, and the two are nested together. The planar spiral coil structure is beneficial for forming a uniform coupling magnetic field outside the dielectric window, and the nested arrangement is beneficial for accommodating two RF coils operating at different frequencies within a limited space.

[0041] In one embodiment, the first RF coil 110 and the second RF coil 120 are arranged concentrically. This concentric arrangement ensures that the coupled magnetic fields generated by the two coils are symmetrically distributed circumferentially, which helps to improve the uniformity of plasma distribution within the process cavity.

[0042] In one embodiment, the first filter 130 and the second filter 140 each include an LC resonant network. By configuring the parameters of the inductance and capacitance in the LC resonant network, the network resonates with low impedance at the operating frequency of the corresponding RF coil and detunes with high impedance at the operating frequency of the other RF coil, thereby achieving frequency-selective grounding.

[0043] In one embodiment, the LC resonant network includes a series inductor and a series capacitor connected in series between the corresponding ground terminal and ground, the series inductor and series capacitor being configured to resonate in series at the operating frequency of the corresponding RF coil.

[0044] like Figure 2 As shown, taking the first filter 130 as an example, it is a bandpass filter, including a first series inductor 131 and a first series capacitor 132 connected in series between the first ground terminal 112 and ground. The first series inductor 131 and the first series capacitor 132 are connected in series, and their series resonant frequency is equal to the first frequency. At the first frequency, the inductive reactance of the first series inductor 131 and the capacitive reactance of the first series capacitor 132 cancel each other out, and the impedance of the series circuit is only the sum of the parasitic resistances of the components, which is close to zero impedance, allowing the radio frequency current of the first frequency to flow smoothly to ground. At the second frequency, the series circuit is detuned and has high impedance, thereby suppressing the radio frequency current of the second frequency from flowing to ground through the first ground terminal 112.

[0045] The second filter 140 adopts the same topology as the first filter 130, including a second series inductor and a second series capacitor connected in series between the second ground terminal 122 and ground, and the series resonant frequency of the two is equal to the second frequency.

[0046] In one embodiment, when the first frequency is lower than the second frequency, the product of the inductance of the first series inductor 131 and the capacitance of the first series capacitor 132 is greater than the product of the inductance of the second series inductor and the capacitance of the second series capacitor. Since the series resonant frequency is inversely proportional to the square root of the product of the inductance and capacitance values, when the first frequency is lower than the second frequency, the product of the inductance and capacitance values ​​corresponding to the first filter 130 is correspondingly greater than the product corresponding to the second filter 140.

[0047] In one embodiment, the LC resonant network further includes a parallel resonant branch connected in series with a series inductor and a series capacitor. The parallel resonant branch includes a notch inductor and a notch capacitor connected in parallel with each other. The parallel resonant branch is configured to resonate in parallel at the operating frequency of another RF coil.

[0048] like Figure 3As shown, taking the first filter 130 as an example, it also includes a parallel resonant branch connected in series with the first series inductor 131 and the first series capacitor 132. This parallel resonant branch includes a first notch inductor 133 and a first notch capacitor 134 connected in parallel, and their parallel resonant frequency is equal to the second frequency. At the second frequency, the first notch inductor 133 and the first notch capacitor 134 resonate in parallel, and the parallel resonant branch exhibits extremely high impedance. This impedance, combined with the series detuned impedance, forms an additional attenuation pole at the second frequency, further improving the suppression capability of the second frequency RF current. At the first frequency, the parallel resonant branch is detuned and exhibits low impedance, which does not affect the normal grounding of the first frequency RF current.

[0049] The second filter 140 adopts the same composite topology as the first filter 130 but with reversed parameter configuration. Its parallel resonant branch includes a second notch inductor and a second notch capacitor connected in parallel, and their parallel resonant frequency is equal to the first frequency.

[0050] In one embodiment, a series inductor and a series capacitor are connected in series between the ground terminal and the intermediate node. The intermediate node is grounded through a notch inductor and a notch capacitor connected in parallel. The notch inductor and the notch capacitor are configured to resonate in parallel at the operating frequency of another RF coil. The intermediate node is also grounded through an additional series inductor and an additional series capacitor. The additional series inductor and the additional series capacitor are configured to resonate in series at the operating frequency of the corresponding RF coil.

[0051] like Figure 5 As shown, taking the first filter 130 as an example, the first series inductor 131 and the first series capacitor 132 are connected in series between the first ground terminal 112 and the intermediate node, and the first series inductor 131 and the first series capacitor 132 resonate in series at the first frequency. The intermediate node is grounded through the first notch inductor 133 and the first notch capacitor 134 connected in parallel, and the first notch inductor 133 and the first notch capacitor 134 resonate in parallel at the second frequency, exhibiting extremely high impedance at the second frequency. The intermediate node is also grounded through the first additional series inductor 136 and the first additional series capacitor 137 connected in series, and the first additional series inductor 136 and the first additional series capacitor 137 resonate in series at the first frequency, exhibiting near-zero impedance at the first frequency.

[0052] At the first frequency, the first series inductor 131 and the first series capacitor 132 resonate in series, exhibiting low impedance; the first notch inductor 133 and the first notch capacitor 134 are detuned, exhibiting low impedance; and the first additional series inductor 136 and the first additional series capacitor 137 resonate in series, exhibiting near-zero impedance. The RF current at the first frequency, after passing through the intermediate node, mainly flows to ground through the first additional series inductor 136 and the first additional series capacitor 137. The first notch inductor 133 also provides a redundant grounding path. At the second frequency, the first series inductor 131 and the first series capacitor 132 are detuned, exhibiting high impedance; the first notch inductor 133 and the first notch capacitor 134 resonate in parallel, exhibiting extremely high impedance; and the first additional series inductor 136 and the first additional series capacitor 137 are detuned, exhibiting high impedance. The RF current at the second frequency is subject to triple blocking, making it difficult to reach ground.

[0053] The second filter 140 adopts the same composite topology as the first filter 130 but with reversed parameter configuration. The second series inductor and the second series capacitor resonate in series at the second frequency, the second notch inductor and the second notch capacitor resonate in parallel at the first frequency, and the second additional series inductor and the second additional series capacitor resonate in series at the second frequency.

[0054] In one embodiment, the first frequency is lower than the second frequency, the first filter 130 is a low-pass filter, and the second filter 140 is a high-pass filter. The cutoff frequencies of both the low-pass filter and the high-pass filter are between the first frequency and the second frequency.

[0055] like Figure 4 As shown, the first filter 130 includes a first low-pass inductor 135 connected in series between the first ground terminal 112 and ground. The inductance value of the first low-pass inductor 135 is configured such that the inductive reactance is small at a first frequency, allowing the radio frequency current of the first frequency to flow to ground through the first low-pass inductor 135; and the inductive reactance is large at a second frequency, making it difficult for the radio frequency current of the second frequency to flow to ground by being blocked by the first low-pass inductor 135.

[0056] The second filter 140 includes a second high-pass capacitor connected in series between the second ground terminal 122 and ground. The capacitance value of the second high-pass capacitor is configured such that the capacitive reactance is small at the second frequency, allowing the radio frequency current of the second frequency to flow to ground through the second high-pass capacitor; and the capacitive reactance is large at the first frequency, making it difficult for the radio frequency current of the first frequency to flow to ground by the second high-pass capacitor.

[0057] In one embodiment, the first feed terminal 111 is electrically connected to the first radio frequency source 150, and the second feed terminal 121 is electrically connected to the second radio frequency source 160. The first radio frequency source 150 outputs a first frequency radio frequency signal, and the second radio frequency source 160 outputs a second frequency radio frequency signal.

[0058] The operation of this embodiment is as follows: The first RF source 150 outputs an RF current of the first frequency, which flows into the first RF coil 110 through the first feed terminal 111, and then to ground through the first ground terminal 112 and the first filter 130. The first filter 130 has a low impedance to the first frequency, thus the grounding loop of the first frequency RF current remains unobstructed. The second RF source 160 outputs an RF current of the second frequency, which flows into the second RF coil 120 through the second feed terminal 121, and then to ground through the second ground terminal 122 and the second filter 140. The second filter 140 has a low impedance to the second frequency, thus the grounding loop of the second frequency RF current remains unobstructed.

[0059] When the second frequency radio frequency current is induced in the first radio frequency coil 110 due to electromagnetic coupling between the coils and flows to the first ground terminal 112, the first filter 130 presents a high impedance to the second frequency, thus suppressing the path of the second frequency radio frequency current to ground through the first ground terminal 112. Similarly, when the first frequency radio frequency current is induced in the second radio frequency coil 120 and flows to the second ground terminal 122, the second filter 140 presents a high impedance to the first frequency, thus suppressing the path of the first frequency radio frequency current to ground through the second ground terminal 122. Therefore, it is difficult for the radio frequency currents of the two frequencies to cross-couple through the grounding path, which helps to reduce cross-coupling and improve the independent adjustment capability of the radio frequency power at each frequency.

[0060] In some embodiments, each inductor may be wound with a hollow copper tube to withstand a larger RF current and reduce high-frequency loss; each capacitor may be a vacuum variable capacitor or a high-power ceramic capacitor to withstand RF voltage and facilitate tuning.

[0061] like Figure 6 As shown, this embodiment also provides a plasma processing apparatus 200, including a process cavity 210, the process cavity 210 having a dielectric window 220, and also including the aforementioned radio frequency component 100, the radio frequency component 100 being disposed on the side of the dielectric window 220 facing away from the process cavity 210, i.e., outside the dielectric window 220. A first radio frequency coil 110 and a second radio frequency coil 120 are arranged in a plane outside the dielectric window 220, and radio frequency energy is coupled into the interior of the process cavity 210 through the dielectric window 220 to excite and maintain the plasma within the process cavity 210.

[0062] The dielectric window 220 can be made of insulating materials such as ceramic or quartz. The process chamber 210 may also be equipped with a base 211 for supporting the substrate to be processed and an air inlet device for introducing process gas.

[0063] Since the plasma processing equipment 200 uses the aforementioned radio frequency component 100, the first filter 130 and the second filter 140 can respectively suppress the cross-current of radio frequency current of another frequency through the grounding path, which helps to reduce the cross-coupling between the first radio frequency coil 110 and the second radio frequency coil 120, so that the radio frequency power of each frequency can be adjusted independently, thereby improving the control accuracy of plasma density and ion energy in the process cavity 210.

[0064] It should be noted that the above embodiments are merely preferred embodiments of the present utility model and are not intended to limit the scope of protection of the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the scope of protection of the present utility model.

Claims

1. A radio frequency (RF) component, comprising a first RF coil and a second RF coil, the first RF coil having a first feed terminal and a first ground terminal for receiving a first frequency RF signal, and the second RF coil having a second feed terminal and a second ground terminal for receiving a second frequency RF signal, characterized in that, It also includes a first filter and a second filter. The first filter is connected in series between the first ground terminal and ground and is configured to allow the first frequency radio frequency signal to pass through and suppress the second frequency radio frequency signal. The second filter is connected in series between the second ground terminal and ground and is configured to allow the second frequency radio frequency signal to pass through and suppress the first frequency radio frequency signal.

2. The radio frequency component according to claim 1, characterized in that, The first filter includes a band-pass filter, a low-pass filter, or a high-pass filter, and the second filter includes a band-pass filter, a low-pass filter, or a high-pass filter.

3. The radio frequency component according to claim 1, characterized in that, Both the first RF coil and the second RF coil are planar spiral coils, with the second RF coil located inside the first RF coil, and the two are nested together.

4. The radio frequency component according to claim 3, characterized in that, The first radio frequency coil and the second radio frequency coil are arranged concentrically.

5. The radio frequency component according to claim 1, characterized in that, The first filter and the second filter each include an LC resonant network.

6. The radio frequency component according to claim 5, characterized in that, The LC resonant network includes a series inductor and a series capacitor connected in series between the corresponding ground terminal and ground. The series inductor and the series capacitor are configured to resonate in series at the operating frequency of the corresponding radio frequency coil.

7. The radio frequency component according to claim 6, characterized in that, The first filter includes a first series inductor and a first series capacitor connected in series between the first ground terminal and ground. The second filter includes a second series inductor and a second series capacitor connected in series between the second ground terminal and ground. The first frequency is less than the second frequency. The product of the inductance value of the first series inductor and the capacitance value of the first series capacitor is greater than the product of the inductance value of the second series inductor and the capacitance value of the second series capacitor.

8. The radio frequency component according to claim 6, characterized in that, The LC resonant network also includes a parallel resonant branch connected in series with the series inductor and the series capacitor. The parallel resonant branch includes a notch inductor and a notch capacitor connected in parallel with each other. The parallel resonant branch is configured to resonate in parallel with the operating frequency of another RF coil.

9. The radio frequency component according to claim 6, characterized in that, The series inductor and the series capacitor are connected in series between the ground terminal and the intermediate node. The intermediate node is grounded through a notch inductor and a notch capacitor connected in parallel. The notch inductor and the notch capacitor are configured to resonate in parallel at the operating frequency of another RF coil. The intermediate node is also grounded through an additional series inductor and an additional series capacitor. The additional series inductor and the additional series capacitor are configured to resonate in series at the operating frequency of the corresponding RF coil.

10. The radio frequency component according to claim 2, characterized in that, The first frequency is lower than the second frequency, the first filter is a low-pass filter, the second filter is a high-pass filter, and the cutoff frequency of the low-pass filter and the cutoff frequency of the high-pass filter are both between the first frequency and the second frequency.

11. The radio frequency component according to claim 1, characterized in that, The first feed terminal is electrically connected to the first radio frequency source, and the second feed terminal is electrically connected to the second radio frequency source. The first radio frequency source outputs a first frequency radio frequency signal, and the second radio frequency source outputs a second frequency radio frequency signal.

12. A plasma processing apparatus, comprising a process chamber having a dielectric window, characterized in that, It also includes a radio frequency component as described in any one of claims 1 to 11, the radio frequency component being disposed outside the dielectric window to excite plasma within the process cavity.

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