Plasma processing device and plasma processing method
By applying a reverse pulse signal to a radio frequency power source in a plasma processing device and adjusting the thickness of the plasma sheath, the problem of etching tilt in the substrate edge region was solved, and the verticality and uniformity of substrate edge etching were achieved.
Patent Information
- Application Number
- CN202411114575.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-13
- Publication Date
- 2026-02-17
AI Technical Summary
During plasma processing, a tilting problem occurs in the edge region of the substrate, mainly due to uneven etching caused by the non-perpendicular direction of positive ion bombardment in the edge region of the substrate.
By setting up an edge source RF power source, an upper electrode bias RF power source, and an edge bias RF power source in the plasma processing device, and applying reverse pulse RF signals to the edge regions of the upper and lower electrodes respectively, the thickness of the plasma sheath is adjusted to ensure that positive ions bombard the edge region of the substrate vertically. Combined with secondary electrons, the positive charge accumulation is neutralized, thus avoiding etching tilt.
It effectively increases the plasma density and secondary electron concentration in the substrate edge region, ensuring vertical etching of the substrate edge region during the etching process, avoiding tilting of the etching holes/grooves at the substrate edge, and improving etching uniformity.
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Figure CN121545979A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of semiconductor processing equipment technology, and specifically to a plasma processing device and a plasma processing method. Background Technology
[0002] Currently, plasma processing equipment typically employs an upper electrode and a lower electrode within the processing chamber, with the substrate to be processed mounted on the lower electrode. During plasma processes such as plasma etching, a high-frequency discharge from a plasma radio frequency power source is applied to either the upper or lower electrode, generating plasma from the process gas. Simultaneously, a bias power supply is applied to the lower electrode to generate a bias voltage on the substrate, accelerating positive ions in the plasma towards the lower electrode. The accelerated positive ions bombard the substrate surface, etching the desired pattern.
[0003] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art:
[0004] Due to factors such as substrate edge effects, substrate edge tilting occurs in high aspect ratio etching due to tilting of the positive ion bombardment direction and accumulation of positive charge at the bottom of the etched area.
[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention
[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.
[0007] This disclosure provides a plasma processing apparatus and a plasma processing method to solve the problem of substrate edge tilting.
[0008] In some embodiments, the plasma processing apparatus includes: a processing chamber including a lower electrode for carrying a substrate and an upper electrode disposed opposite to the lower electrode; an edge source radio frequency power source for applying a first radio frequency signal to an edge region of the upper electrode and / or the lower electrode, wherein the first radio frequency signal is used to generate plasma in the edge region between the upper electrode and the lower electrode; an upper electrode bias radio frequency power source for applying a second radio frequency signal to the upper electrode, wherein the second radio frequency signal is used to adjust the thickness of the plasma sheath layer on the surface of the edge region of the upper electrode; and an edge bias radio frequency power source for applying a third radio frequency signal to the edge region of the lower electrode, wherein the third radio frequency signal is used to adjust the thickness of the plasma sheath layer on the surface of the edge region of the lower electrode; wherein the second radio frequency signal and the third radio frequency signal are synchronized by an inverse pulse signal.
[0009] Optionally, the processing chamber further includes: an electrostatic chuck for supporting the substrate; an edge ring surrounding the electrostatic chuck; and an edge electrode disposed below the edge ring or on the edge ring itself for introducing radio frequency power into the edge region of the lower electrode.
[0010] Optionally, the edge source radio frequency power source is further configured to apply the first radio frequency signal to the edge electrode to perform high-frequency discharge in the edge region between the upper and lower electrodes through the edge electrode; the edge bias radio frequency power source is further configured to apply the third radio frequency signal to the edge electrode to provide a bias voltage in the edge region of the lower electrode through the edge electrode; wherein the frequency of the first radio frequency signal is much greater than the frequency of the third radio frequency signal.
[0011] Optionally, the plasma processing apparatus further includes: a center source radio frequency power source for applying the fourth radio frequency signal to the central region of the lower electrode to perform high-frequency discharge in the central region between the upper and lower electrodes; and a center bias radio frequency power source for applying the fifth radio frequency signal to the central region of the lower electrode to provide a bias voltage in the central region of the lower electrode; wherein the frequency of the fourth radio frequency signal is much greater than the frequency of the fifth radio frequency signal.
[0012] Optionally, the second radio frequency signal and the fifth radio frequency signal are synchronized by a reverse pulse signal; the third radio frequency signal and the fifth radio frequency signal are synchronized by a synchronization pulse signal.
[0013] Optionally, the first radio frequency signal and the fourth radio frequency signal are inverted pulse signals with a phase difference from the second radio frequency signal; the third radio frequency signal and the fifth radio frequency signal are inverted pulse signals with a phase difference from the second radio frequency signal; the second radio frequency signal is delayed by the first radio frequency signal, the third radio frequency signal, the fourth radio frequency signal and the fifth radio frequency signal, and the delay period is less than or equal to 10µs.
[0014] Optionally, the frequencies of the first and fourth radio frequency signals are 1MHz-200MHz; the frequencies of the second, third, and fifth radio frequency signals are 100kHz-20MHz.
[0015] Optionally, the center-biased RF power source and the edge-biased RF power source are pulsed DC power supplies, and the output frequency of the pulsed DC power supply is 50kHz-1MHz.
[0016] Optionally, the plasma processing apparatus further includes: a pulse signal control unit, which is electrically connected to the center source radio frequency power source, the center bias radio frequency power source, the edge source radio frequency power source, the edge bias radio frequency power source, and the upper electrode bias radio frequency power source, respectively, for providing pulse control signals to individually control the first radio frequency signal and the fourth radio frequency signal, or for providing pulse control signals to synchronously control the first radio frequency signal, the third radio frequency signal, the fourth radio frequency signal, and the fifth radio frequency signal.
[0017] In some embodiments, the plasma processing method includes:
[0018] The substrate to be processed is placed in a plasma processing apparatus as described in this invention;
[0019] A reactive gas is introduced into the plasma processing chamber, and the reactive gas is ionized into plasma in the outer region of the plasma region by an edge source radio frequency power source.
[0020] The plasma located in the outer region of the plasma region is accelerated and bombarded on the surface of the upper electrode by the upper electrode bias radio frequency power source and the edge bias radio frequency power source, so that a large number of secondary electrons are generated in the outer region of the plasma region.
[0021] The plasma processing apparatus and plasma processing method provided in this disclosure can achieve the following technical effects:
[0022] By applying a first radio frequency (RF) signal to the edge region of the upper and / or lower electrodes using an edge-source RF power source, a higher concentration of plasma can be generated in the edge region, thereby increasing the plasma density in the edge region. Simultaneously, a second RF signal is applied to the upper electrode using an upper electrode bias RF power source. This second RF signal is used to adjust the thickness of the plasma sheath in the edge region of the upper electrode. Combined with the higher concentration of plasma in the edge region, this achieves a stronger bombardment effect on the upper electrode, resulting in a higher concentration of secondary electrons in the edge region of the substrate. These secondary electrons can neutralize the positive charge accumulation at the bottom of the deep holes / grooves in the edge region of the substrate.
[0023] Furthermore, a third radio frequency (RF) signal is applied to the edge region of the lower electrode via an edge-biased RF power source. This third RF signal adjusts the thickness of the plasma sheath in the substrate edge region, allowing positive ions to bombard the substrate edge region vertically downwards. By synchronizing a second RF signal with a reverse pulse signal, when the lower electrode edge-biased RF source supplies power to the lower electrode edge region, positive ions in the plasma can bombard the substrate edge region vertically downwards, thereby etching vertically downward-facing deep holes / grooves in the edge region. When the upper electrode biased RF power source supplies power to the upper electrode, the number of secondary electrons in the edge region increases. These increased secondary electrons rapidly accumulate positive charge at the bottom of the vertically downward-facing deep holes / grooves in the edge region. The combined effect of these two mechanisms effectively prevents the tiling problem of etched holes / grooves at the substrate edge.
[0024] The above general description and the description below are exemplary and explanatory only, and are not intended to limit the invention. Attached Figure Description
[0025] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein:
[0026] Figure 1 This is a schematic diagram of the structure of an plasma processing device provided in an embodiment of this disclosure;
[0027] Figure 2 This is a timing diagram of the radio frequency power of a plasma processing apparatus performing a plasma etching process according to an embodiment of this disclosure;
[0028] Figure 3 This is a timing diagram of the radio frequency power during a plasma etching process using another plasma processing apparatus provided in this embodiment of the present disclosure;
[0029] Figure 4This is a timing diagram of the radio frequency power during a plasma etching process using another plasma processing apparatus provided in this embodiment of the present disclosure;
[0030] Figure 5 This is a schematic diagram of another plasma processing device provided in an embodiment of this disclosure;
[0031] Figure 6 This is a schematic diagram of another plasma processing device provided in an embodiment of this disclosure;
[0032] Figure 7 This is a schematic diagram of the secondary electron distribution in a plasma etching process of a plasma processing apparatus provided in an embodiment of this disclosure;
[0033] Figure 8 This is a timing diagram of the radio frequency power during a plasma etching process using another plasma processing apparatus provided in this embodiment of the present disclosure;
[0034] Figure 9 This is a timing diagram of the radio frequency power during a plasma etching process using another plasma processing apparatus provided in this embodiment of the present disclosure;
[0035] Figure 10 This is a schematic diagram of another plasma processing device provided in an embodiment of this disclosure.
[0036] Figure label:
[0037] 10-Upper electrode; 11-Electrostatic chuck; 12-Plasma region; 13-Inner electrode; 14-Edge electrode; 15-Metal base; 16-Edge ring; 17-Ceramic layer; 18-RF matching unit; 19-Pulse signal control unit; 20-Edge source RF power source; 21-Upper electrode bias RF power source; 22-Edge bias RF power source; 23-Center source RF power source; 24-Center bias RF power source. Detailed Implementation
[0038] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.
[0039] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.
[0040] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better description of the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this disclosure according to the specific circumstances.
[0041] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.
[0042] Unless otherwise stated, the term "multiple" means two or more.
[0043] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.
[0044] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.
[0045] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.
[0046] In related technologies, semiconductor chip manufacturing processes include the generation of plasma, and the positive ions and / or free radicals generated after plasma dissociation. These positive ions and / or free radicals are used to directly or indirectly influence changes on the surface of a substrate exposed to the plasma. For example, various plasma-based processes can be used to etch materials from a substrate surface, deposit materials onto a substrate surface, or modify materials already present on a substrate surface. Plasma is typically generated by applying radio frequency (RF) power to a reactive gas in a controlled environment, thereby exciting the reactive gas and converting it into the desired plasma.
[0047] Furthermore, the plasma processing apparatus in this embodiment includes a processing chamber in which reactive gases are introduced. A clamping plate (e.g., an electrostatic clamping plate or a mechanical clamping plate) for holding a substrate is disposed at the lower part of the processing chamber. The substrate can be a semiconductor substrate to be processed or a glass plate to be processed into a flat panel display. A lower electrode is disposed in the clamping plate. Simultaneously, a spray plate for reactive gases and an upper electrode are disposed at the top of the processing chamber, opposite to the lower electrode.
[0048] Combination Figure 1 As shown, this embodiment of the present disclosure provides a plasma processing apparatus, including a processing chamber, an edge source radio frequency power source 20, an upper electrode bias radio frequency power source 21, and an edge bias radio frequency power source 22. The processing chamber includes a lower electrode for supporting a substrate and an upper electrode 10 disposed opposite to the lower electrode, and a plasma region 12 containing plasma with adjustable density is formed between the upper electrode 10 and the lower electrode. The edge source radio frequency power source 20 applies a first radio frequency signal RF1 to the edge region of the upper electrode 10 and / or the lower electrode. The first radio frequency signal RF1 generates plasma in the edge region between the upper electrode 10 and the lower electrode. The upper electrode bias radio frequency power source 21 applies a second radio frequency signal RF2 to the upper electrode 10, and the second radio frequency signal RF2 adjusts the thickness of the plasma sheath layer on the surface of the edge region of the upper electrode 10. The edge bias radio frequency power source 22 applies a third radio frequency signal RF3 to the edge region of the lower electrode, and the third radio frequency signal RF3 adjusts the thickness of the plasma sheath layer on the surface of the edge region of the lower electrode. The second radio frequency signal RF2 and the third radio frequency signal RF3 are synchronized by an inverse pulse signal.
[0049] Using the plasma processing apparatus provided in this embodiment, a first radio frequency signal RF1 is applied to the edge region of the upper electrode and / or lower electrode via an edge source radio frequency power source, which generates a higher concentration of plasma in the edge region, thereby increasing the plasma density in the edge region. Simultaneously, a second radio frequency signal RF2 is applied to the upper electrode via an upper electrode bias radio frequency power source. The second radio frequency signal RF2 is used to adjust the thickness of the plasma sheath in the edge region of the upper electrode. Combined with the higher concentration of plasma in the edge region, this achieves a stronger bombardment effect on the edge of the upper electrode, resulting in a higher concentration of secondary electrons in the edge region of the substrate. These secondary electrons can neutralize the positive charge accumulation at the bottom of the deep holes / grooves in the edge region of the substrate.
[0050] Furthermore, a third radio frequency (RF) signal RF3 is applied to the edge region of the lower electrode via an edge-biased RF power source. RF3 adjusts the thickness of the plasma sheath in the substrate edge region, allowing positive ions to bombard the edge region vertically downwards. This invention synchronizes a second RF signal RF2 with a reverse pulse signal to the third RF signal RF3. When the edge-biased RF source supplies power to the lower electrode edge region, positive ions in the plasma bombard the substrate edge region vertically downwards, thereby etching vertically downward-facing deep holes / grooves in the edge region. When the upper electrode biased RF power source supplies power to the upper electrode, the number of secondary electrons in the edge region increases. These increased secondary electrons rapidly accumulate positive charge at the bottom of the vertically downward-facing deep holes / grooves in the edge region. The combined effect of these two signals effectively prevents the tiling problem of the etched holes / grooves at the substrate edge.
[0051] In one embodiment of the present invention, combined with Figure 1 As shown, an edge ring 16 is provided on the electrostatic chuck 11 (ESC), which typically serves as an energized electrode and supports the substrate. The edge ring 16 surrounds the electrostatic chuck 11. The edge ring 16 is typically used to perform various functions, such as regulating the temperature and electric field distribution in the edge region and protecting lower components not protected by the substrate itself from damage by plasma ions. For example, the substrate is positioned above the electrostatic chuck 11 and surrounded by the edge ring 16, and the lower electrode is positioned on the electrostatic chuck 11 or is the electrostatic chuck 11 itself.
[0052] In one embodiment of the present invention, the electrostatic chuck 11 serves as a base for carrying the substrate and may include a metal base 15 and a ceramic layer 17 located above the metal base 15. In this case, the metal base 15 acts as the lower electrode, and the ceramic layer 17 is typically used to provide a current path from the metal base 15 to the edge ring 16. Radio frequency signals can be applied to the metal base 15 and coupled into the plasma region 12 through the ceramic layer 17.
[0053] In another embodiment of the present invention, the lower electrode includes an inner electrode 13 and an edge electrode 14. The inner electrode 13 is located within the ceramic layer 17 or is the metal substrate 15 itself. The inner electrode 13 is directly electrically connected to the radio frequency (RF) line of the RF power source to introduce RF (power) power into the substrate. The edge electrode 14 is disposed below the edge ring 16 or is the edge ring 16 itself to introduce RF (power) power into the edge region of the lower electrode, thereby controlling the plasma at the edge of the substrate and improving etching uniformity.
[0054] Of course, it should be noted that the specific locations of the inner electrode 13 and the edge electrode 14 include any arrangement and combination described above. Figure 1 Only one method is shown in the image. In this way, by coupling the radio frequency (power) power to the electrostatic chuck 11, the capacitive coupling efficiency of the substrate can be increased.
[0055] In one embodiment of the present invention, combined with Figure 1 As shown, the plasma processing apparatus of the present invention further includes a central source radio frequency power source 23 and a central bias radio frequency power source 24. The central source radio frequency power source 23 is used to apply a fourth radio frequency signal RF4 to the inner electrode 13, thereby generating plasma in the central portion of the plasma region 12 and ensuring the plasma density in the central portion of the plasma region 12. The central bias radio frequency power source 24 is used to apply a fifth radio frequency signal RF5 to the inner electrode 13, causing positive ions in the central portion of the plasma region 12 to accelerate and bombard the substrate with the lower electrode, thereby performing positive ion etching.
[0056] Furthermore, the plasma processing apparatus of the present invention also includes a plurality of radio frequency matching units 18, which are used to couple the radio frequency power of the edge source radio frequency power source 20, the upper electrode bias radio frequency power source 21, the edge bias radio frequency power source 22, the center source radio frequency power source 23 and the center bias radio frequency power source 24 to the processing chamber by capacitive coupling through one radio frequency matching unit 18.
[0057] Furthermore, it is known that the processing chamber of the plasma processing apparatus of the present invention introduces a total of five radio frequency signals. Specifically, the edge source radio frequency power source 20 is further used to apply a first radio frequency signal RF1 to the edge electrode 14, thereby outputting radio frequency power corresponding to the first radio frequency signal RF1 to the edge electrode 14, so as to perform high-frequency discharge in the edge region between the upper electrode 10 and the lower electrode through the edge electrode 14. The upper electrode bias radio frequency power source 21 is further used to apply a second radio frequency signal RF2 to the upper electrode 10, thereby outputting radio frequency power corresponding to the second radio frequency signal RF2 to the upper electrode 10, so as to provide a bias voltage in the edge region of the upper electrode 10. The edge bias radio frequency power source 22 is further used to apply a third radio frequency signal RF3 to the edge electrode 14, thereby outputting radio frequency power corresponding to the third radio frequency signal RF3 to the edge electrode 14, so as to provide a bias voltage in the edge region of the lower electrode through the edge electrode 14. The center source radio frequency power source 23 is further used to apply a fourth radio frequency signal RF4 to the inner electrode 13, thereby outputting radio frequency power corresponding to the fourth radio frequency signal RF4 to the inner electrode 13, so as to perform high-frequency discharge in the central region between the upper electrode 10 and the lower electrode. The center bias RF power source is further used to apply a fifth RF signal RF5 to the inner electrode 13, thereby outputting RF power corresponding to the fifth RF signal RF5 to the inner electrode 13 to provide a bias voltage in the center region of the lower electrode.
[0058] In this configuration, the frequency of the first radio frequency signal RF1 is significantly higher than that of the third radio frequency signal RF3. The frequency of the fourth radio frequency signal RF4 is significantly higher than that of the fifth radio frequency signal RF5. Optionally, the first radio frequency signal RF1 and the fourth radio frequency signal RF4 are high-frequency signals, with a frequency range of 1MHz-200MHz, used to generate plasma. The second radio frequency signal RF2, the third radio frequency signal RF3, and the fifth radio frequency signal RF5 are low-frequency signals, with a frequency range of 100kHz-20MHz, used to provide bias voltage.
[0059] In the above embodiments, the plasma processing apparatus of the present invention further includes a pulse signal control unit 19. The pulse signal control unit 19 is electrically connected to the center source RF power source 23, the center bias RF power source 24, the edge source RF power source 20, the edge bias RF power source 22, and the upper electrode bias RF power source 21, respectively, to provide pulse control signals to individually control the first RF signal RF1 and the fourth RF signal RF4. Alternatively, it can provide pulse control signals to synchronously control the first RF signal RF1, the third RF signal RF3, the fourth RF signal RF4, and the fifth RF signal RF5. That is, the pulse signal control unit 19 can control the on / off times of the first RF signal RF1, the second RF signal RF2, the third RF signal RF3, the fourth RF signal RF4, and / or the fifth RF signal RF5 through the pulse control signals. When the pulse control signal is high, the corresponding RF power source outputs high RF power; when the pulse control signal is low, the corresponding RF power source outputs low RF power or zero power. Optionally, the frequency range of the pulse signal control unit 19 can be 10Hz-10kHz.
[0060] In one embodiment of the present invention, combined with Figure 2 As shown, the second radio frequency signal RF2 and the fifth radio frequency signal RF5 of this invention can be synchronized by an inverted pulse signal. The third radio frequency signal RF3 and the fifth radio frequency signal RF5 can be synchronized by a synchronization pulse signal. Here, "inverted pulse signal" refers to two pulse signals with the same frequency but opposite high-level outputs. Simply put, when the pulse synchronization signal controlling the second radio frequency signal RF2 is high, the pulse synchronization signal controlling the fifth radio frequency signal RF5 is low; that is, when the second radio frequency signal RF2 outputs high power, the fifth radio frequency signal RF5 outputs low power, and vice versa. "Synchronization pulse signal" refers to two pulse signals with the same frequency and in-phase high-level outputs.
[0061] In one embodiment of the present invention, combined with Figure 3 As shown, in this invention, the pulse synchronization signals controlling the first radio frequency signal RF1 and the fourth radio frequency signal RF4 can always be kept at a high level, so that the radio frequency power output by the edge source radio frequency power source 20 and the center source radio frequency power source 23 is always at a high power. In this way, the plasma can be better kept from extinguishing.
[0062] In one embodiment of the present invention, combined with Figure 4As shown, the first radio frequency signal RF1 of the present invention can always be kept at a high level, so that the radio frequency power output by the edge source radio frequency power source 20 is always high. In this way, the plasma density in the outer region of the plasma region 12 can be increased, so that a higher secondary electron concentration can be obtained in this region, so as to neutralize the charge accumulated in the edge region of the substrate more quickly, thereby solving the problem of substrate edge tilting.
[0063] In one specific application of the present invention, combined with Figure 5 As shown, when the third RF signal RF3 and the fifth RF signal RF5 are high-level signals and the second RF signal RF2 is low-level signal, the edge-biased RF power source 22 and the center-biased RF power source 24 output high power, while the upper electrode-biased RF power source 21 outputs low power or zero power. At this time, the edge-biased RF power source 22 and the center-biased RF power source 24 generate a negative self-bias voltage on the substrate. This negative self-bias voltage generates a plasma sheath layer on the surface of the substrate, causing the plasma region 12 to be closer to the upper electrode 10. Furthermore, the negative bias voltage accelerates positive ions down the electrode into the substrate to be processed, and the accelerated positive ions bombard the substrate surface, thereby performing positive ion etching.
[0064] In another specific application of the present invention, combined with Figure 6 As shown, when the third RF signal RF3 and the fifth RF signal RF5 are low-level signals, and the second RF signal RF2 is a high-level signal, the edge-biased RF power source 22 and the center-biased RF power source 24 output low power or 0 power, while the upper electrode-biased RF power source 21 outputs high power. At this time, a negative self-bias voltage generates a plasma sheath near the upper electrode 10, forcing the plasma region 12 to be closer to the lower electrode. Furthermore, combined with... Figure 7 As shown, when the upper electrode biased RF power source 21 outputs high power, due to the presence of the plasma sheath near the upper electrode 10, positive ions located in the outer region of the plasma region 12 accelerate and bombard the surface of the upper electrode 10. Due to the bombardment of positive ions, the upper electrode 10 emits a large number of high-energy secondary electrons. These secondary electrons are then accelerated towards the lower electrode within the plasma sheath and enter the bottom of the etched pattern. Furthermore, because the plasma region 12 is closer to the lower electrode, the rate at which negative ions generated by the deactivated electrons of the plasma attaching to neutral molecules, atoms, or atomic groups enter the bottom of the etched pattern also increases.
[0065] In this way, because the secondary electrons have high energy and a small scattering angle, they can easily reach the bottom of the etched pattern, thereby neutralizing the positive charge accumulated in the edge region of the substrate. That is, by adjusting the output power of the edge source radio frequency power source 20, the present invention can adjust the plasma density in the outer region of the plasma region 12, so as to obtain a higher secondary electron concentration in this region, so as to neutralize the positive charge accumulated in the edge region of the substrate more quickly, thereby solving the problem of substrate edge tilting.
[0066] In one embodiment of the present invention, combined with Figure 8 As shown, the first radio frequency signal RF1, the third radio frequency signal RF3, the fourth radio frequency signal RF4, and the fifth radio frequency signal RF5 of this invention are synchronous pulse signals, and all of them are out-of-phase pulse signals with a phase difference from the second radio frequency signal RF2. Therefore, this invention allows for five delay periods where all radio frequency powers are low, facilitating the free diffusion of positive and negative ions in the plasma. Of course, the delay period of this phase difference should not be too long, for example, less than 10 μs, to avoid plasma extinction.
[0067] In one embodiment of the present invention, combined with Figure 9 As shown, the first radio frequency signal RF1 and the fourth radio frequency signal RF4 of this invention are radio frequency signals that are continuously maintained at a high frequency. The third radio frequency signal RF3 and the fifth radio frequency signal RF5 are synchronous pulse signals, and both are out-of-phase pulse signals with a phase difference from the second radio frequency signal RF2. Therefore, this invention allows for three delay periods where the radio frequency power is low, which facilitates the free diffusion of positive and negative ions in the plasma. Of course, the delay period of this phase difference should not be too long, for example, less than 10 μs, to avoid plasma extinction.
[0068] Optionally, combined Figure 10 As shown, the center-biased RF power source 24 and the edge-biased RF power source 22 of the present invention can be pulsed DC power supplies (PDC). Optionally, the output frequency of the pulsed DC power supply can be 50kHz-1MHz.
[0069] It is important to note that in this embodiment, the "Source RF power source" is used for high-frequency discharge to generate plasma from the reactive gas. The "Bias RF power source" in this embodiment is used to generate a negative self-bias voltage, accelerating positive ions in the plasma to the downward electrode. The accelerated positive ions bombard the substrate surface to etch the desired pattern. Furthermore, the "inverted pulse signal" mentioned above means that the pulse signals of the two RF power sources have the same period and a sum of 100% duty cycles. The "synchronous pulse signal" in this embodiment refers to a pulse signal with completely identical phase, period, and duty cycle. The "low level" in this embodiment includes both the case where the power pulse signal is zero when the power source is off and the pulse signal is at low power.
[0070] Furthermore, this disclosure also provides a plasma processing method, including the following steps:
[0071] The substrate to be processed is placed in a plasma processing apparatus as described in this invention;
[0072] A reactive gas is introduced into the plasma processing chamber, and the reactive gas is ionized into plasma in the outer region of the plasma region by an edge source radio frequency power source.
[0073] The plasma located in the outer region of the plasma region is accelerated and bombarded on the surface of the upper electrode by the upper electrode bias radio frequency power source and the edge bias radio frequency power source, so that a large number of secondary electrons are generated in the outer region of the plasma region.
[0074] In summary, the present invention applies a first radio frequency signal RF1 to the edge region of the upper electrode and / or the lower electrode by means of an edge source radio frequency power source. The first radio frequency signal RF1 is used to generate a large amount of plasma in the outer region of the plasma region, thereby increasing the plasma density in the outer region of the plasma region and thus obtaining a higher secondary electron concentration in the outer region of the plasma region, so as to neutralize the accumulated charge in the outer region of the substrate more quickly, thereby solving the problem of substrate edge tilting.
[0075] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.
Claims
1. A plasma processing device, characterized in that, include: The processing chamber includes a lower electrode and an upper electrode disposed opposite to the lower electrode; An edge source radio frequency power source is used to apply a first radio frequency signal to the edge region of the upper electrode and / or the lower electrode, wherein the first radio frequency signal is used to generate plasma in the edge region between the upper electrode and the lower electrode; An upper electrode bias radio frequency power source is used to apply a second radio frequency signal to the upper electrode, and the second radio frequency signal is used to adjust the thickness of the plasma sheath layer on the surface of the edge region of the upper electrode; An edge-biased radio frequency power source is used to apply a third radio frequency signal to the edge region of the lower electrode, the third radio frequency signal being used to adjust the thickness of the plasma sheath layer on the surface of the edge region of the lower electrode; The second radio frequency signal and the third radio frequency signal are synchronized by a reverse pulse signal.
2. The plasma processing apparatus according to claim 1, characterized in that, The processing chamber further includes: An electrostatic chuck, used to support a substrate; An edge ring is provided around the electrostatic chuck; An edge electrode, disposed below the edge ring or on the edge ring itself, is used to introduce radio frequency power into the edge region of the lower electrode.
3. The plasma processing apparatus according to claim 2, characterized in that, The edge source radio frequency power source is further used to apply the first radio frequency signal to the edge electrode so as to perform high-frequency discharge through the edge electrode in the edge region between the upper electrode and the lower electrode; The edge bias RF power source is further used to apply the third RF signal to the edge electrode to provide a bias voltage in the edge region of the lower electrode through the edge electrode; The frequency of the first radio frequency signal is much greater than the frequency of the third radio frequency signal.
4. The plasma processing apparatus according to claim 1, characterized in that, Also includes: A central source radio frequency power source is used to apply the fourth radio frequency signal to the central region of the lower electrode to perform high-frequency discharge in the central region between the upper electrode and the lower electrode. A center-biased radio frequency power source is used to apply the fifth radio frequency signal to the center region of the lower electrode to provide a bias voltage in the center region of the lower electrode; The frequency of the fourth radio frequency signal is much greater than the frequency of the fifth radio frequency signal.
5. The plasma processing apparatus according to claim 4, characterized in that, The second radio frequency signal and the fifth radio frequency signal are synchronized by an inverted pulse signal; The third radio frequency signal and the fifth radio frequency signal are synchronized by a synchronization pulse signal.
6. The plasma processing apparatus according to claim 4, characterized in that, The first radio frequency signal and the fourth radio frequency signal are inverse pulse signals that have a phase difference from the second radio frequency signal; The third radio frequency signal and the fifth radio frequency signal are inverse pulse signals with a phase difference from the second radio frequency signal; The second radio frequency signal is delayed by the first, third, fourth and fifth radio frequency signals, and the delay period is less than or equal to 10µs.
7. The plasma processing apparatus according to claim 4, characterized in that, The frequencies of the first and fourth radio frequency signals are 1MHz-200MHz; The frequencies of the second, third, and fifth radio frequency signals are 100kHz-20MHz.
8. The plasma processing apparatus according to claim 4, characterized in that, The center-biased RF power source and the edge-biased RF power source are pulsed DC power supplies, and the output frequency of the pulsed DC power supply is 50kHz-1MHz.
9. The plasma processing apparatus according to any one of claims 4 to 8, characterized in that, Also includes: The pulse signal control unit is electrically connected to the center source RF power source, the center bias RF power source, the edge source RF power source, the edge bias RF power source, and the upper electrode bias RF power source, respectively, to provide pulse control signals to individually control the first RF signal and the fourth RF signal, or to provide pulse control signals to synchronously control the first RF signal, the third RF signal, the fourth RF signal, and the fifth RF signal.
10. A plasma processing method, characterized in that, include: The substrate to be processed is placed in the plasma processing apparatus as described in any one of claims 1 to 9; A reactive gas is introduced into the plasma processing chamber, and the reactive gas is ionized into plasma in the outer region of the plasma region by an edge source radio frequency power source. The plasma located in the outer region of the plasma region is accelerated and bombarded on the surface of the upper electrode by the upper electrode bias radio frequency power source and the edge bias radio frequency power source, so that a large number of secondary electrons are generated in the outer region of the plasma region.