Plasma etching apparatus

Abstract

The utility model discloses a kind of plasma etching devices, belong to semiconductor technical field, and plasma etching device includes: chamber, the inside of chamber forms vacuum airtight space;Lower electrode, it is set in chamber;Upper electrode, it is set in chamber, and it is oppositely arranged with lower electrode;Coil assembly, it is set in chamber;Electrode power supply mechanism, for applying high-frequency current between upper electrode and lower electrode, to generate high-frequency electric field;Coil power supply mechanism, for supplying high-frequency current to coil assembly, to generate magnetic field;And acoustic generator, it is set in chamber, for sending high-frequency acoustic wave into chamber, to form acoustic field in the chamber. By the utility model provides a kind of plasma etching device, can solve the technical problem of uneven etching of wafer different regions.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor technology, and in particular to a plasma etching apparatus. Background Technology

[0002] Plasma etching is a dry etching technique based on plasma activation reaction. It achieves precise processing of microstructures through the physicochemical interaction between high-energy ions and materials. This technique complements photolithography in chip manufacturing.

[0003] During plasma etching, various factors can lead to uneven etching. For example, discontinuities in the electric field at the wafer edge cause gradient changes, affecting etching uniformity. Potential changes between the bias surface and the ground and suspended surfaces create voltage gradients at the wafer edge, causing the plasma sheath within the etching chamber to bend and altering the ion trajectory relative to the wafer. Gas flow fields formed at the vacuum port and asymmetric gas distribution also contribute to uneven edge potential, resulting in etching non-uniformity. This non-uniformity not only reduces device dimensional accuracy but can also cause faults such as short circuits and open circuits, directly impacting wafer yield. Utility Model Content

[0004] The purpose of this invention is to provide a plasma etching apparatus that can solve the technical problem of uneven etching in different areas of a wafer.

[0005] To solve the above-mentioned technical problems, this utility model is achieved through the following technical solution: This utility model provides a plasma etching apparatus, comprising at least: A chamber, the interior of which forms a vacuum, sealed space; The lower electrode is disposed within the cavity; The upper electrode is disposed within the cavity and is positioned opposite to the lower electrode. A coil assembly is disposed within the cavity; An electrode power supply mechanism is used to apply a high-frequency current between the upper electrode and the lower electrode to generate a high-frequency electric field; A coil power supply mechanism for supplying high-frequency current to the coil assembly to generate a magnetic field; and A sound wave generator is disposed within the cavity and is used to send high-frequency sound waves into the cavity to form a sound field within the cavity.

[0006] In one embodiment of this utility model, the sound wave generator is disposed on the inner wall of the chamber.

[0007] In one embodiment of this utility model, there are two sound wave generators, which are located on two opposite inner walls of the cavity.

[0008] In one embodiment of this utility model, the sound wave generator is a ring sound wave generator.

[0009] In one embodiment of this utility model, a damping structure is provided between the sound wave generator and the inner wall of the cavity, and the damping structure is used to prevent the high-frequency sound wave from being transmitted to the inner wall of the cavity.

[0010] In one embodiment of the present invention, the damping structure includes a damping layer, and a mounting groove is provided on the side of the damping layer facing the sound wave generator. The sound wave generator is located in the mounting groove, and the side of the sound wave generator away from the damping layer can expose the outer surface of the damping layer.

[0011] In one embodiment of this utility model, the sound wave generator is a directional sound wave generator, and the sound output end of the directional sound wave generator faces the center of the cavity.

[0012] In one embodiment of this utility model, the coil assembly is located below the lower electrode.

[0013] In one embodiment of the present invention, the coil assembly includes a plurality of coils evenly distributed along the length direction of the lower electrode.

[0014] In one embodiment of the present invention, the plasma etching apparatus further includes a focusing ring and an equivalent flow shielding ring disposed on the lower electrode. The focusing ring is used to surround the outer periphery of the wafer, and the equivalent flow shielding ring surrounds the outer periphery of the focusing ring.

[0015] In summary, the plasma etching device provided by this utility model has the following unexpected effect: a sound field is formed by the sound wave generator, a high-frequency electric field is formed between the upper and lower electrodes, and a magnetic field is formed by the coil assembly. The three physical fields (electric field, magnetic field, and sound field) are coupled to each other and work together to affect the plasma. Charged particles (such as electrons) experience the Lorentz force in a magnetic field, causing them to spiral around magnetic field lines, increasing the probability of collisions between electrons and gas molecules and improving plasma density. High-frequency sound waves emitted by the acoustic generator propagate within the etching gas, generating nonlinear effects and forming stable micro-eddies. These eddies stir the gas near the surfaces of the upper and lower electrodes, breaking stagnant boundary layers and promoting the transport of etching gas and byproducts. They also accelerate the movement of the etching gas, improving gas distribution uniformity and increasing the probability of ion collisions. The acoustic flow effect (formed by high-frequency vibrations to create directional fluid motion) enhances gas convection, reducing the temperature difference across the wafer surface and preventing process fluctuations caused by thermal instability, thus improving process stability. The micro-scale eddies generated by acoustic vibrations enable more uniform gas distribution and improve gas diffusion. Combined with the confinement effect of the electromagnetic field on the plasma, this enhances the etching load effect for high aspect ratio structures, improving etching uniformity. The etching uniformity is adjusted by controlling the magnetic field strength through the control of the coil component current and the acoustic wave amplitude.

[0016] Of course, any product implementing this utility model does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of a plasma etching apparatus in one embodiment.

[0019] Label Explanation: 11-Cavity; 12-Lower electrode; 121-Second RF source; 122-Second matching unit; 13-Upper electrode; 131-First RF source; 132-First matching unit; 14-Coil assembly; 15-Acoustic wave generator; 16-Damping structure; 17-Focusing ring; 18-Equivalent current shielding ring. Detailed Implementation

[0020] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model.

[0021] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of this utility model. Therefore, the drawings only show the components related to this utility model and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0022] In this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first" and "second" are used only for descriptive and distinguishing purposes and should not be construed as indicating or implying relative importance.

[0023] It should be noted that the electric field is the foundation and plasma source; the magnetic field is responsible for the macroscopic, large-scale control of plasma density distribution; and the acoustic field is responsible for the microscopic, localized transport of reactants and control of particle distribution.

[0024] Please see Figure 1 As shown, in one embodiment, the plasma etching apparatus includes: Chamber 11, the interior of chamber 11 forms a vacuum-sealed space; The lower electrode 12 is disposed inside the chamber 11; The upper electrode 13 is disposed inside the chamber 11 and is positioned opposite to the lower electrode 12. Coil assembly 14 is disposed inside chamber 11; An electrode power supply mechanism is used to apply a high-frequency current between the upper electrode 13 and the lower electrode 12 to generate a high-frequency electric field. A coil power supply mechanism for supplying high-frequency current to the coil assembly 14 to generate a magnetic field; and A sound wave generator 15 is disposed inside the chamber 11 and is used to send high-frequency sound waves into the chamber 11 to form a sound field inside the chamber 11.

[0025] Specifically, the interior of chamber 11 is vacuum and sealed. The upper electrode 13 is located at the top of chamber 11, and the lower electrode 12 is located at the bottom of chamber 11, with the upper electrode 13 and lower electrode 12 facing each other and parallel to each other. The lower electrode 12 can serve as a substrate, with the wafer placed on top of it. In some examples, the lower electrode 12 is located on a substrate at the bottom of chamber 11. A coil assembly 14 and a sound wave generator 15 are disposed within chamber 11. An electrode power supply mechanism is used to apply a high-frequency current between the upper electrode 13 and the lower electrode 12 to generate a high-frequency electric field; a coil power supply mechanism is used to supply a high-frequency current to the coil assembly 14 to generate a magnetic field; and the sound wave generator 15 is used to transmit high-frequency sound waves into chamber 11.

[0026] The electrode power supply mechanism may include two radio frequency (RF) power matching systems: a first RF power matching system and a second RF power matching system. The first RF power matching system includes a first RF source 131 and a first matching device 132, and the second RF power matching system includes a second RF source 121 and a second matching device 122. For example, the upper electrode 13 can be connected to a higher frequency first RF source 131 (e.g., 60 MHz) and a first matching device 132 to control ion dissociation or plasma density in the reactive gas; simultaneously, a lower frequency second RF source 121 (e.g., 13.56 MHz) and a second matching device 122 can be connected to the lower electrode 12 to introduce a bias voltage to control the ion energy and energy distribution incident on the wafer.

[0027] The coil power supply mechanism includes a matching unit and a high-frequency power supply connected to the matching unit. The high-frequency power supply for the coil assembly 14 is DC powered, supplying high-frequency power to the coil assembly 14 to generate an induced magnetic field within the chamber 11. Then, in this state, etching gas is supplied to the chamber 11, and the induced magnetic field plasmas the etching gas. High-frequency acoustic waves induce microscale eddies in the gas, enhancing gas diffusion; the acoustic flow promotes gas convection, reduces local hot spots, and improves temperature uniformity.

[0028] The chamber 11 is connected to an air intake device for supplying the required reaction gas into the chamber 11. In some embodiments, the air intake device is connected to the top of the chamber 11, but the air intake device is not limited to being connected to the top of the chamber 11. The chamber 11 is connected to an exhaust device for extracting or discharging the reaction gas within the chamber 11. Exemplarily, the air intake device may be a gas pipe, and the exhaust device may be an exhaust pipe and an exhaust pump installed on the exhaust pipe, etc.

[0029] In this embodiment, an unexpected effect is that a sound field is formed by the sound wave generator 15, a high-frequency electric field is formed between the upper electrode 13 and the lower electrode 12, and a magnetic field is formed by the coil assembly 14. The three physical fields (electric field, magnetic field and sound field) are coupled to each other and work together to act on the plasma. Charged particles (such as electrons) in a magnetic field experience the Lorentz force, causing them to spiral around the magnetic field lines, increasing the probability of collisions between electrons and gas molecules and improving plasma density. The high-frequency sound waves emitted by the acoustic generator 15 propagate within the etching gas, generating a nonlinear effect that forms stable micro-eddies. These eddies agitate the gas near the surfaces of the upper electrode 13 and lower electrode 12, breaking stagnant boundary layers and promoting the transport of etching gas and byproducts. They also accelerate the movement of the etching gas, improving gas distribution uniformity and increasing the probability of ion collisions. The acoustic flow effect (formed by high-frequency vibrations to create directional fluid motion) enhances gas convection, reducing the temperature difference across the entire wafer surface, preventing process fluctuations caused by thermal instability, and improving process stability. The micro-scale eddies generated by the acoustic vibrations enable more uniform gas distribution, improving gas diffusion capacity. Combined with the confinement effect of the electromagnetic field on the plasma, this enhances the etching load effect for high aspect ratio structures, improving etching uniformity. The etching uniformity is adjusted by controlling the magnetic field strength through the current in the coil assembly 14 and the acoustic wave amplitude.

[0030] Please see Figure 1 As shown, in one embodiment of this utility model, the sound wave generator 15 is disposed on the inner wall of the chamber 11. Sound waves are mechanical waves that require a medium (solid, gas, or liquid) to propagate. The chamber 11 is a solid structure with high density and large inertia, requiring more energy to generate measurable vibrations. Furthermore, since the energy density of high-frequency sound waves (0.5~2.5 MHz) is low, it is insufficient to drive the solid, resulting in significant sound wave loss.

[0031] An unexpected effect is that by placing the sound wave generator 15 inside the chamber 11, the vibration energy generated by the sound wave generator 15 mainly enters the adjacent gas molecules through direct radiation, causing gas pressure fluctuations (sound pressure). The gas molecules have small mass and strong fluidity, and are easily excited to form sound wave eddies, which can make the gas more evenly distributed, improve the gas diffusion ability, and thus improve the etching uniformity.

[0032] Please see Figure 1 As shown, in one embodiment of this invention, there are two acoustic wave generators 15, located on two opposite inner walls of the chamber 11. High-frequency acoustic waves have short wavelengths and are easily absorbed by gas molecules, resulting in significant energy loss over long distances. An unexpected effect is that by setting two opposite acoustic wave generators 15, the diffusion capability of the gas near the inner wall of the chamber 11 (wafer edge) can be simultaneously improved, thereby enhancing etching uniformity.

[0033] Please see Figure 1 As shown, in one embodiment of this utility model, the acoustic wave generator 15 is a ring acoustic wave generator. An unexpected effect is that the ring acoustic wave generator can simultaneously send acoustic waves in many directions, thereby simultaneously improving the diffusion capacity of gas at many locations within the chamber 11, and further improving the etching uniformity.

[0034] Please see Figure 1 As shown, in one embodiment of this utility model, a damping structure 16 is provided between the sound wave generator 15 and the inner wall of the corresponding chamber 11. The damping structure 16 is used to block the transmission of high-frequency sound waves to the inner wall of the chamber 11. The damping structure 16 includes a high-damping material such as alumina ceramic. High-frequency sound waves have extremely short wavelengths and decay rapidly in gases, with their energy quickly converted into gas kinetic energy (sound flow). They are difficult to transmit through the gas to the wafer surface, so high-frequency sound waves have virtually no effect on the wafer itself. Furthermore, because the inherent frequency of solid structures such as wafers is usually low (<1 kHz), which is significantly different from the frequency of high-frequency sound waves, high-frequency sound waves can prevent wafer resonance. In addition, the lower electrode 12 adsorbs the wafer through electrostatic force, and its adsorption force on the wafer is greater than the vibration caused by the sound waves. An unexpected effect is that by installing a damping structure 16 between the sound wave generator 15 and the cavity wall, the sound waves in the direction of the cavity 11 are absorbed by the damping structure 16. By absorbing the vibration energy, the sound waves are blocked from being transmitted to the solid, thus preventing the cavity 11 from resonating and avoiding the impact of resonance on the wafer etching.

[0035] Please see Figure 1 As shown, in one embodiment of the present invention, the damping structure 16 includes a damping layer. A mounting groove is provided on the side of the damping layer facing the sound wave generator 15. The sound wave generator 15 is located entirely in the mounting groove, and the side of the sound wave generator 15 away from the damping layer can expose the outer surface of the damping layer.

[0036] Specifically, a mounting groove is provided on the side of the damping layer facing the center of the chamber 11, and the acoustic wave generator 15 is mounted in the mounting groove. The damping layer can cover the acoustic wave generator 15, exposing only the side of the acoustic wave generator 15 facing the center of the chamber 11. An unexpected effect is that, through the above structure, the acoustic wave generator 15 can directionally send sound waves towards the center of the chamber 11, which can prevent the sound waves from propagating to the inner wall of the chamber 11, avoid resonance in the chamber 11, and thus avoid resonance affecting wafer etching.

[0037] Please see Figure 1 As shown, in one embodiment of this utility model, the sound wave generator 15 is a directional sound wave generator, and the sound output end of the directional sound wave generator faces the center of the cavity 11. An unexpected effect is that it can prevent sound waves from propagating to the inner wall of the cavity 11, avoid resonance in the cavity 11, and thus avoid resonance affecting wafer etching.

[0038] Please see Figure 1 As shown, in one embodiment of this invention, the coil assembly 14 is located below the lower electrode 12. In one example, the coil assembly 14 may be located below the outer bottom wall of the chamber 11; in another example, the coil assembly 14 may be located at the bottom of the lower electrode 12. An unexpected effect is that the above arrangement allows the coil assembly 14 to be closer to the wafer, improving the potential regulation effect.

[0039] Please see Figure 1 As shown, in one embodiment of this utility model, the coil assembly 14 includes a plurality of coils evenly distributed along the length direction of the lower electrode 12. An unexpected effect is that adding multiple sets of coils below the lower electrode 12 allows for magnetic field compensation at different locations, improving the edge potential of the wafer; it enables adjustment of the wafer's edge potential under different process conditions, ensuring etching uniformity; adjusting the coil current or frequency can control the sheath potential, optimize the etching process, and achieve precise etching of the wafer surface.

[0040] Please see Figure 1 As shown, in one embodiment of the present invention, the plasma etching apparatus further includes a focusing ring 17 and an equivalent flow shielding ring 18 disposed on the lower electrode 12. The focusing ring 17 is used to surround the outer periphery of the wafer, and the equivalent flow shielding ring 18 surrounds the outer periphery of the focusing ring 17.

[0041] An unexpected effect is that adding a focusing ring 17 to the edge of the wafer can effectively regulate the edge potential; the equivalent current shielding ring 18 can confine the plasma, suppress the radio frequency field to the area near the wafer, and allow the exhaust gas to leave the chamber 11.

[0042] In summary, this utility model provides a plasma etching apparatus, comprising: Chamber 11, the interior of chamber 11 forms a vacuum-sealed space; The lower electrode 12 is disposed inside the chamber 11; The upper electrode 13 is disposed inside the chamber 11 and is positioned opposite to the lower electrode 12. Coil assembly 14 is disposed inside chamber 11; An electrode power supply mechanism is used to apply a high-frequency current between the upper electrode 13 and the lower electrode 12 to generate a high-frequency electric field. A coil power supply mechanism for supplying high-frequency current to the coil assembly 14 to generate a magnetic field; and The sound wave generator 15 is installed inside the chamber 11 and is used to send high-frequency sound waves into the chamber 11.

[0043] The plasma etching device provided by this utility model has an unexpected effect: a sound field is formed by the sound wave generator 15, a high-frequency electric field is formed between the upper electrode 13 and the lower electrode 12, and a magnetic field is formed by the coil assembly 14. The three physical fields (electric field, magnetic field and sound field) are coupled to each other and work together to act on the plasma. Charged particles (such as electrons) in a magnetic field experience the Lorentz force, causing them to spiral around the magnetic field lines, increasing the probability of collisions between electrons and gas molecules and improving plasma density. The high-frequency sound waves emitted by the acoustic generator 15 propagate within the etching gas, generating a nonlinear effect that forms stable micro-eddies. These eddies agitate the gas near the surfaces of the upper electrode 13 and lower electrode 12, breaking stagnant boundary layers and promoting the transport of etching gas and byproducts. They also accelerate the movement of the etching gas, improving gas distribution uniformity and increasing the probability of ion collisions. The acoustic flow effect (formed by high-frequency vibrations to create directional fluid motion) enhances gas convection, reducing the temperature difference across the entire wafer surface, preventing process fluctuations caused by thermal instability, and improving process stability. The micro-scale eddies generated by the acoustic vibrations enable more uniform gas distribution, improving gas diffusion capacity. Combined with the confinement effect of the electromagnetic field on the plasma, this enhances the etching load effect for high aspect ratio structures, improving etching uniformity. The etching uniformity is adjusted by controlling the magnetic field strength through the current in the coil assembly 14 and the acoustic wave amplitude.

[0044] The embodiments of this utility model disclosed above are merely illustrative of the present utility model. The embodiments do not exhaustively describe all details, nor do they limit the utility model to the specific implementations described. Obviously, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it. This utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A plasma etching apparatus, characterized in that, include: A chamber, the interior of which forms a vacuum, sealed space; The lower electrode is disposed within the cavity; The upper electrode is disposed within the cavity and is positioned opposite to the lower electrode. A coil assembly is disposed within the cavity; An electrode power supply mechanism is used to apply a high-frequency current between the upper electrode and the lower electrode to generate a high-frequency electric field; A coil power supply mechanism is used to supply high-frequency current to the coil assembly to generate a magnetic field; as well as A sound wave generator is disposed within the cavity and is used to send high-frequency sound waves into the cavity to form a sound field within the cavity.

2. The plasma etching apparatus according to claim 1, characterized in that, The sound wave generator is mounted on the inner wall of the chamber.

3. The plasma etching apparatus according to claim 2, characterized in that, The number of sound wave generators is two, and they are located on two opposite inner walls of the chamber, respectively.

4. The plasma etching apparatus according to claim 2 or 3, characterized in that, The sound wave generator is a ring sound wave generator.

5. The plasma etching apparatus according to claim 4, characterized in that, A damping structure is provided between the sound wave generator and the inner wall of the cavity, and the damping structure is used to prevent the high-frequency sound wave from being transmitted to the inner wall of the cavity.

6. The plasma etching apparatus according to claim 5, characterized in that, The damping structure includes a damping layer, and a mounting groove is provided on the side of the damping layer facing the sound wave generator. The sound wave generator is located in the mounting groove, and the side of the sound wave generator away from the damping layer can expose the outer surface of the damping layer.

7. The plasma etching apparatus according to claim 2, characterized in that, The sound wave generator is a directional sound wave generator, and the sound output end of the directional sound wave generator faces the center of the cavity.

8. The plasma etching apparatus according to claim 1, characterized in that, The coil assembly is located below the lower electrode.

9. The plasma etching apparatus according to claim 8, characterized in that, The coil assembly includes a plurality of coils evenly distributed along the length of the lower electrode.

10. The plasma etching apparatus according to claim 1, characterized in that, The plasma etching apparatus further includes a focusing ring and an equivalent flow shielding ring disposed on the lower electrode. The focusing ring is used to surround the outer periphery of the wafer, and the equivalent flow shielding ring surrounds the outer periphery of the focusing ring.

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