Highly efficient etching method and equipment based on microwave ECR and radio frequency plasma coupling

Abstract

This invention discloses a highly efficient etching method and apparatus based on microwave ECR and radio frequency plasma coupling, relating to the field of plasma etching technology. It includes a cylindrical metal waveguide, the interior of which is divided into an upper cavity and a lower etching region. Multiple rectangular waveguides, communicating with the interior of the cylindrical metal waveguide, are evenly distributed on the outer wall of the upper cavity. Each rectangular waveguide has a microwave input port at its end, communicating with a microwave source. The upper cavity contains a quartz cavity communicating with a gas flow inlet and a coil wound around the outer wall of the quartz cavity. The two ends of the coil are connected to a DC power supply and / or a radio frequency power supply via wires. The interior of the quartz cavity is a plasma discharge region. This invention utilizes electron cyclotron resonance technology and radio frequency plasma inductive coupling technology to jointly control the microwave plasma, improving the energy conversion efficiency from microwave to plasma and generating a more uniform plasma, significantly increasing the etching area and achieving highly efficient etching.

Description

Technical Field

[0001] This invention relates to the field of plasma etching technology, and more specifically to the field of efficient etching methods and equipment based on microwave ECR and radio frequency plasma coupling. Background Technology

[0002] Plasma technology is widely used in industrial processes, including semiconductor manufacturing, material surface treatment, cleaning, and etching. Plasma consists of partially or fully ionized gas containing electrons, ions, and neutral particles, and can be generated under high temperatures or electromagnetic fields. Plasma technologies typically include microwave plasma (MWP), radio frequency inductively coupled plasma (ICP), and microwave electron cyclotron resonance (ECR).

[0003] Microwave plasma (MWP) technology is an advanced fabrication technique that uses electromagnetic waves at microwave frequencies (2.45 GHz or 915 MHz) to excite a plasma state. This technology offers advantages such as high ionization efficiency, no electrode contamination, and the ability to operate over a wide pressure range. Microwave plasma is particularly important in etching and thin film deposition processes because it provides high-density plasma, enabling higher processing speeds and better uniformity. However, the stability and efficiency of microwave plasma systems can be challenged when faced with varying operating conditions, such as gas type and pressure changes.

[0004] Radio frequency inductively coupled plasma (ICP) technology generates and sustains plasma by using a magnetic field in a coil to produce a radio frequency current. ICP technology is characterized by its ability to generate high-density plasma at low pressure, good uniformity, and the ability to independently control ion energy and plasma density. This makes it very useful in precision etching and deposition processes. However, ICP is also quite sensitive to changes in equipment design and operating conditions.

[0005] Microwave electron cyclotron resonance (ECR) technology uses microwaves of a specific frequency to induce electrons to cyclotron in a magnetic field, thereby efficiently ionizing gas molecules to generate plasma. The advantage of ECR ​​lies in its ability to operate at relatively low gas pressures, producing high-density and low-temperature plasmas, which is ideal for processes requiring precise control, such as microstructure etching. ECR plasma sources can provide a stable plasma flow, but require highly precise control of the magnetic field.

[0006] Microwave plasma (MWP) technology produces plasma with poor uniformity, which easily erodes the outer wall of the reaction cavity; microwave electron cyclotron resonance (ECR) technology is an extension of microwave plasma (MWP) technology, which improves the uniformity of plasma by confining the trajectory of electrons with a strong magnetic field; radio frequency inductively coupled plasma (ICP) technology has good uniformity, but a low ionization rate.

[0007] Existing plasma cleaning and etching equipment generally uses one of the three plasma technologies mentioned above, which has shortcomings in robustness. When conditions such as gas type, gas concentration, pressure, and input power change, the plasma morphology is prone to significant changes, leading to large variations in the plasma's absorption capacity for electromagnetic waves. This results in significant reflections and reduces the efficiency of microwave-to-plasma conversion. Furthermore, existing equipment is pressure-sensitive and generally can only operate within a specific pressure range, failing to achieve plasma control under wide pressure conditions. Summary of the Invention

[0008] The purpose of this invention is to address the technical problems of low microwave-to-plasma conversion efficiency and poor plasma uniformity in existing microwave plasma cleaning and etching equipment. This invention provides a high-efficiency etching device and method based on microwave ECR and radio frequency plasma coupling. This solution utilizes electron cyclotron resonance technology and radio frequency plasma inductive coupling technology to jointly regulate microwave plasma, improving the energy conversion efficiency from microwave to plasma and generating a more uniform plasma, significantly increasing the etching area and achieving high-efficiency etching. Simultaneously, this invention improves the flexibility of plasma processing over a wide pressure range, enabling efficient and uniform excitation of different pressures and raw material gases. Furthermore, the device in this patent has the advantage of a large adjustable parameter range, allowing for customization according to the requirements of the sample to be etched.

[0009] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0010] The first aspect of the present invention provides a high-efficiency etching apparatus based on microwave ECR and radio frequency plasma coupling, including a cylindrical metal waveguide, an airflow inlet disposed at the upper end of the cylindrical metal waveguide and an airflow outlet disposed at the lower end of the cylindrical metal waveguide. The interior of the cylindrical metal waveguide is divided into an upper cavity and a lower etching region. Multiple rectangular waveguides communicating with the interior of the cylindrical metal waveguide are evenly distributed on the outer wall of the cylindrical metal waveguide corresponding to the upper cavity. Each rectangular waveguide has a microwave input port communicating with a microwave source at its end.

[0011] The upper cavity contains a quartz cavity connected to the airflow inlet and a coil wound around the outer wall of the quartz cavity. The two ends of the coil are connected to a DC power supply and / or a radio frequency power supply through wires. The inside of the quartz cavity is a plasma discharge region.

[0012] Specifically, such as Figure 1 and Figure 2As shown, a coil is wound around the periphery of the quartz cavity. The two ends of the coil can be loaded with either direct current (DC) or radio frequency alternating current (RF AC) (typically 13.56MHz), or both currents simultaneously. RF protection circuitry is added to protect the DC power supply, and DC protection circuitry is added to protect the RF power supply. A cylindrical metal waveguide is also located around the quartz tube, and four standard BJ22 rectangular waveguides feed microwaves into the cylindrical waveguide. The vacuum quartz cavity is a plasma discharge region; the generated plasma is then blown into the etching region.

[0013] The electric field distribution in the discharge region with and without coil under no-load conditions is as follows: Figure 3 As shown, it is easy to see that after adding the coil, the electric field is more concentrated in the discharge cavity, and the electric field distribution is more uniform.

[0014] In one embodiment, both the cylindrical metal waveguide and the quartz cavity are cylindrical cavities, and the axis of the cylindrical metal waveguide and the axis of the quartz cavity coincide.

[0015] In one embodiment, each microwave input port is provided with a tuning three-pin device for adjusting the efficiency of the fed microwave energy.

[0016] Specifically, each microwave input port is equipped with a tuning three-pin device to regulate the efficiency of the fed microwave energy.

[0017] In one embodiment, there are four rectangular waveguides, which are radially distributed on the outer wall of the cylindrical metal waveguide.

[0018] In one embodiment, the four microwave input ports have the same microwave input power. The four microwave input ports are sequentially designated as a first port, a second port, a third port, and a fourth port. The first port and the third port are in phase, the second port and the fourth port are in phase, and the phase difference between the first port and the second port is 180°.

[0019] Specifically, the microwave input power of the four microwave input ports is the same, the first port and the third port are in phase, the second port and the fourth port are in phase, and the phase difference between the first port and the second port is 180°.

[0020] The amplitude and phase of the microwave input port also significantly affect the electromagnetic field distribution, thereby influencing the uniformity and size of the plasma. In actual production, the input power and phase of the electromagnetic field waves at the four ports can be changed based on electromagnetic field simulation results, thus controlling the plasma by modulating the electromagnetic waves.

[0021] In one embodiment, the etching zone is located below the quartz cavity, and the etching zone is provided with an etching sample processing stage for placing the etching sample and a pressing component for pressing the etching sample on the etching sample processing stage.

[0022] Specifically, there is a platen in this area for placing the sample to be etched. There is a mechanical control component below it, which can be used to control the lifting of the platen for picking up and placing the sample to be etched. There is a quartz pressing plate above the platen to fix the sample. The whole device maintains a low-pressure environment by pumping air from the bottom. Figure 2 The dotted line in the figure indicates the air flow direction.

[0023] In one embodiment, a mass flow meter is provided at the air flow inlet outside the quartz cavity.

[0024] Specifically, a mass flow meter (MFC) is connected directly above the cavity to control the intake rate of the target raw material gas.

[0025] The second aspect of the present invention provides an efficient etching method based on the coupling of microwave ECR and radio frequency plasma. The above-mentioned efficient etching equipment based on the coupling of microwave ECR and radio frequency plasma has three single modes: microwave plasma mode, electron cyclotron resonance microwave plasma mode, and radio frequency inductively coupled plasma mode. By controlling the type of current in the coil and taking the pressure of the gas to be processed as a criterion, the efficient etching equipment selectively selects three different single modes.

[0026] The first mode: When no current passes through the coil and the air pressure P > 100 Pa, the microwave plasma mode is adopted.

[0027] In this mode, the plasma is completely excited by microwaves. In this mode, the plasma ionization rate is high, the variable range of air pressure is wide, the electron density is high, but when the power is high, the plasma energy efficiency is low.

[0028] The second mode: When a direct current passes through the coil and the air pressure P < 10 Pa, the electron cyclotron resonance microwave plasma mode is adopted. At this time, the constant magnetic field generated by the direct current acts on the electrons in the plasma to produce cyclotron resonance, and the ionization efficiency is improved. However, this method is only suitable for working under low pressure and relatively low temperature conditions, and the microwave input power is low.

[0029] The third mode: When the microwave source is turned off, a radio frequency current passes through the coil, and the air pressure 1 Pa < P < 100 Pa, the radio frequency inductively coupled plasma mode is adopted. At this time, the plasma is only excited by the alternating magnetic field generated by the coil. At this time, the plasma distribution area is large and the uniformity is good, but precise radio frequency matching is required, and at the same time, the ionization rate is low.

[0030] The third aspect of the present invention provides an efficient etching method based on the coupling of microwave ECR and radio frequency plasma. The above-mentioned efficient etching equipment based on the coupling of microwave ECR and radio frequency plasma proposes two working processes based on the type of the gas to be processed as a criterion.

[0031] The first working process: For Penning gas (easily ionized gas), it can usually be excited and discharged under low power and low pressure, which meets the applicable conditions of electron cyclotron resonance. The plasma excited by the electron cyclotron resonance microwave plasma mode itself has high uniformity, and the efficiency of microwave coupling to plasma is high. The plasma can be further controlled by adjusting the microwave power and gas pressure. If there is still a problem of uneven plasma discharge, further control can be achieved by coupling radio frequency plasma technology.

[0032] The second workflow: For gases with high ionization energy, the excitation threshold is high, requiring a strong electric field to break down the gas. Therefore, microwave plasma is used as the main excitation method. After plasma excitation, the plasma discharge state can be adjusted by adjusting the microwave energy and power. If uneven discharge occurs, radio frequency current can be added to the coil to regulate the uniformity of the plasma and increase the degree of plasma dissociation. If the plasma absorbs less microwave power, DC current can be added to the coil to increase the energy efficiency of microwave coupling to the plasma by utilizing the principle of electron cyclotron resonance.

[0033] Ultimately, this device aims to achieve a uniform, highly efficient, large-area, and effective plasma source under different gas pressure environments and raw material gas types.

[0034] The beneficial effects of the present invention are as follows:

[0035] 1. This invention couples ECR and ICP technologies, which can maintain high-density plasma while leveraging the low-temperature characteristics of ECR ​​and the uniformity of ICP to achieve better process control and higher energy efficiency. This coupling method can alleviate the instability of a single technology when faced with changes in operating conditions.

[0036] 2. This invention utilizes electron cyclotron resonance technology and radio frequency plasma inductive coupling technology to jointly regulate microwave plasma, thereby improving the energy conversion efficiency from microwave to plasma and generating more uniform plasma, significantly increasing the etching area and achieving efficient etching. At the same time, this invention improves the flexibility of plasma processing within a wide pressure range, enabling efficient and uniform excitation of different pressures and different raw material gases.

[0037] 3. The device in this invention also has the advantage of a large range of adjustable parameters. It can adjust ① the amplitude and phase of different microwave feed ports; ② the amplitude of DC current; ③ the amplitude and frequency of radio frequency current; ④ the flow rate of raw material gas; ⑤ the pressure in the reaction chamber; and ⑥ the height of the etching sample stage according to the requirements of the sample to be etched, thereby exciting the generation of plasmas of different types and sizes. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the structure of the high-efficiency etching device based on microwave ECR and radio frequency plasma coupling of the present invention.

[0040] Figure 2 yes Figure 1 A partial 3D image.

[0041] Figure 3 It is a simulation diagram of the electric field comparison between etching equipment with and without coils.

[0042] Figure 4 This is a schematic diagram of the magnetic flux density mode when the current in the coil is 14.5A.

[0043] Figure 5 This is a simulation flowchart of the plasma discharge process under the influence of a magnetic field.

[0044] Figure 6 This is a simulation diagram of the modulation effect on plasma after adding radio frequency current.

[0045] Figure 7 This is a simulation diagram of the electric field distribution under different input powers.

[0046] Figure 8 This is a simulation diagram of the electron density distribution under different input powers.

[0047] Figure 9 This is a simulation diagram of the electron temperature distribution under different input powers.

[0048] Figure 10 This is a simulation diagram of the gas temperature distribution under different input powers.

[0049] Figure 11 This is a graph showing the energy efficiency of microwave coupling into plasma under different input powers.

[0050] Figure 12 These are simulation diagrams of electric field intensity under different radio frequency currents.

[0051] Figure 13 These are simulation graphs of electron temperature under different radio frequency currents.

[0052] Figure 14 This is a graph showing the energy efficiency of microwave coupling to plasma under different radio frequency currents.

[0053] Figure 15 These are flowcharts for three single-mode incentive methods.

[0054] Figure 16 This is a flowchart of microwave electron cyclotron resonance and radio frequency plasma coupling to excite plasma. Detailed Implementation

[0055] To make the technical problems, technical solutions, and technical effects of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0057] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0058] In the description of the embodiments of the present invention, it should be noted that the terms "inner", "outer", "upper", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention 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 limiting the present invention.

[0059] Example 1

[0060] This embodiment provides a high-efficiency etching device based on microwave ECR and radio frequency plasma coupling, including a cylindrical metal waveguide, an airflow inlet disposed at the upper end of the cylindrical metal waveguide, and an airflow outlet disposed at the lower end of the cylindrical metal waveguide. The interior of the cylindrical metal waveguide is divided into an upper cavity and a lower etching area. Multiple rectangular waveguides that communicate with the interior of the cylindrical metal waveguide are evenly distributed on the outer wall of the cylindrical metal waveguide corresponding to the upper cavity. Each rectangular waveguide has a microwave input port that communicates with a microwave source at its end.

[0061] The upper cavity contains a quartz cavity connected to the airflow inlet and a coil wound around the outer wall of the quartz cavity. The two ends of the coil are connected to a DC power supply and / or a radio frequency power supply through wires. The inside of the quartz cavity is a plasma discharge region.

[0062] Specifically, such as Figure 1 and Figure 2 As shown, a coil is wound around the periphery of the quartz cavity. The two ends of the coil can be loaded with either direct current (DC) or radio frequency alternating current (RF AC) (typically 13.56MHz), or both currents simultaneously. RF protection circuitry is added to protect the DC power supply, and DC protection circuitry is added to protect the RF power supply. A cylindrical metal waveguide is also located around the quartz tube, and four standard BJ22 rectangular waveguides feed microwaves into the cylindrical waveguide. The vacuum quartz cavity is a plasma discharge region; the generated plasma is then blown into the etching region.

[0063] The electric field distribution in the discharge region with and without coil under no-load conditions is as follows: Figure 3 As shown, it is easy to see that after adding the coil, the electric field is more concentrated in the discharge cavity, and the electric field distribution is more uniform.

[0064] Both the cylindrical metal waveguide and the quartz cavity are cylindrical cavities, and the axis of the cylindrical metal waveguide and the axis of the quartz cavity coincide.

[0065] Each microwave input port is equipped with a tuning three-pin device for adjusting the efficiency of the fed microwave energy.

[0066] Specifically, each microwave input port is equipped with a tuning three-pin device to regulate the efficiency of the fed microwave energy.

[0067] There are four rectangular waveguides, which are distributed radially around the outer wall of the cylindrical metal waveguide.

[0068] The four microwave input ports have the same microwave input power. The four microwave input ports are sequentially named port 1, port 2, port 3, and port 4. Port 1 and port 3 are in phase, port 2 and port 4 are in phase, and the phase difference between port 1 and port 2 is 180°.

[0069] Specifically, the microwave input power of the four microwave input ports is the same, the first port and the third port are in phase, the second port and the fourth port are in phase, and the phase difference between the first port and the second port is 180°.

[0070] The etching zone is located below the quartz cavity. The etching zone is equipped with an etching sample processing stage for placing the etching sample and a pressing component on the etching sample processing stage for pressing the etching sample.

[0071] Specifically, this area contains a base for placing the sample to be etched, and a quartz pressure plate above the base to hold the sample in place. The entire device is maintained at a low pressure by bottom evacuation. Figure 2 The dashed line indicates the direction of airflow.

[0072] A mass flow meter is installed at the airflow inlet on the outside of the quartz cavity.

[0073] Specifically, a mass flow meter (MFC) is connected directly above the cavity to control the intake rate of the target raw material gas.

[0074] Investigating the effect of coil turns on the central field strength of the plasma discharge region:

[0075] Microwaves are fed in from four microwave input ports, generating a strong electric field at the center of the plasma discharge region, which subsequently excites the generation of plasma. The effect of the number of coil turns on the field distribution is studied, and the simulation results are shown in Table 1 below.

[0076] Table 1. Influence of Coil Turns Number on the Center Field Strength of the Plasma Discharge Region

[0077]

[0078] Studies have found that an appropriate number of coil turns is beneficial for focusing the electric field and helps to excite the plasma. When the number of coil turns is 12, the center field strength can reach up to 4.7×104 (V / m). Adding coils is beneficial for focusing the center field strength.

[0079] A coil is uniformly wound around a quartz tube. The number of turns and the current flowing through the coil are set to control the magnetic field, including both direct current (DC) and radio frequency (RF) current, thereby modulating the plasma. In the simulation, only the magnitude of the coil current is shown, without distinguishing between DC and RF currents. The current in the coil is set to 14.5A, and the magnetic flux density is as follows: Figure 4 As shown.

[0080] exist Figure 4 A magnetic flux density is generated from bottom to top, and this magnetic field can be used to control the plasma discharge process. This magnetic flux density is consistent with the actual distribution.

[0081] Study of microwave plasma discharge process under the influence of magnetic field:

[0082] like Figure 6 As shown, in the absence of radio frequency current, the electron density is concentrated in the center of the discharge region, and the addition of... Figure 4As shown in the simulation, after unidirectional coupling with the radio frequency (RF) current, the plasma spreads throughout the entire discharge region, becoming more concentrated near the edge of the quartz wall. The addition of the RF current demonstrates the control over the plasma. As the RF current gradually increases, the plasma tends to accumulate from the center to the edge. The arrows in the simulation diagram represent the diffusion electron flux. Without current, the plasma exhibits a divergent distribution from the center to the edge; after adding the RF current, the electron diffusion flux along... Figure 4 The magnetic flux distribution shown indicates a larger plasma area. This simulation result demonstrates that adding a magnetic field can effectively improve the uniformity of microwave plasma and increase the plasma discharge region.

[0083] Investigating the effects of different radio frequency currents and microwave powers on plasma:

[0084] Changing the microwave input power significantly alters the plasma parameters. The electric field distribution within the device at different input powers (400W, 600W, 800W, 1000W) is as follows. Figure 7 As shown.

[0085] It is easy to observe that at lower input power, the plasma cannot be effectively excited, and the electric field can penetrate the plasma, accumulating within the quartz cavity. As the power increases, the region closest to the microwave feed port is excited first, forming a sheath. With further increases in input power, the sheath surrounding the plasma becomes more stable. The region corresponding to the sheath is the area of ​​concentrated plasma electron density, as shown below. Figure 8 As shown.

[0086] Figure 8 The black line represents the electron density of 7.6 × 10¹⁶ (1 / m²). 3 The contour lines represent the critical electron density of plasma excitation at 2.45 GHz. The area within these contour lines can be considered the plasma region. It is easy to see that the contour region expands significantly with increasing power, and the central electron density also increases further, resulting in a wide coverage of the plasma region.

[0087] In plasma, electron temperature is a physical quantity describing the intensity of electron thermal motion. Electrons in plasma gain energy under the influence of electric fields, magnetic fields, and collisions between particles, thus undergoing thermal motion. The electron temperature in this model is as follows: Figure 9 As shown.

[0088] Gas temperature is a physical quantity characterizing the intensity of thermal motion of heavy particles (such as atoms and molecules) in a plasma. Gas temperature is primarily determined by collisions between heavy particles and their energy exchange with the environment. In plasma, heavy particles constantly collide with each other, transferring energy through these collisions to reach a state of thermal equilibrium. The intensity of thermal motion in this equilibrium state is measured by gas temperature. In this model, the gas temperature increases significantly with increasing power, as follows: Figure 10 As shown.

[0089] Changing the input power can also significantly affect the energy efficiency of microwave coupling to plasma, as follows: Figure 11 As shown, as the power increases from 450W, the energy efficiency first increases and then decreases. The energy efficiency is highest at 800W, reaching 95%. Subsequently, as the power increases further, the energy efficiency decreases slightly, demonstrating the regulatory effect of changing the input power on the plasma.

[0090] Keeping the total power at 1000W, calculate the effect of different currents on electron density. Figure 12 As shown, when the radio frequency current is low, the plasma is not fully excited above the reaction chamber, resulting in an irregular sheath layer. As the radio frequency current increases, the plasma above is fully excited, and the field strength above also exhibits TEM distribution characteristics.

[0091] Figure 13 This demonstrates how radio frequency current can regulate electron temperature.

[0092] Changing the current also has a significant impact on the energy efficiency of microwave coupling to plasma. Specifically, as the current increases, the energy efficiency increases significantly. When the input current is greater than 30A, the energy efficiency increases to 82.68%, and when the input current is greater than 40A, the energy efficiency of microwave coupling to plasma exceeds 90%. The trend of energy efficiency with current is shown below. Figure 14 As shown.

[0093] Example 2

[0094] like Figure 15 As shown, this embodiment provides a high-efficiency etching method based on microwave ECR and radio frequency plasma coupling. The high-efficiency etching equipment based on microwave ECR and radio frequency plasma coupling has three single modes: microwave plasma mode, electron cyclotron resonance microwave plasma mode, and radio frequency inductively coupled plasma mode. By controlling the type of current in the coil and using the pressure of the gas to be processed as a criterion, the high-efficiency etching equipment selects one of the three different single modes.

[0095] The first mode: when no current passes through the coil and the air pressure P > 100 Pa, the microwave plasma mode is adopted;

[0096] In this mode, the plasma is completely excited by microwaves. In this mode, the plasma ionization rate is high, the variable range of air pressure is wide, the electron density is high, but when the power is high, the plasma energy efficiency is low;

[0097] The second mode: when a direct current passes through the coil and the air pressure P < 10 Pa, the electron cyclotron resonance microwave plasma mode is adopted; at this time, the constant magnetic field generated by the direct current acts on the electrons in the plasma to cause cyclotron resonance, and the ionization efficiency is improved, but this method is only suitable for working under low pressure and relatively low temperature conditions, and the microwave input power is low;

[0098] The third mode: when the microwave source is turned off, a radio frequency current passes through the coil, and the air pressure 1 Pa < P < 100 Pa, the radio frequency inductively coupled plasma mode is adopted. At this time, the plasma is only excited by the alternating magnetic field generated on the coil. At this time, the plasma distribution area is large and the uniformity is good, but precise radio frequency matching is required, and at the same time, the ionization rate is low.

[0099] Example 3

[0100] As Figure 16 shown, this example provides an efficient etching method based on the coupling of microwave ECR and radio frequency plasma. Using the above-mentioned efficient etching equipment based on the coupling of microwave ECR and radio frequency plasma, the efficient etching equipment proposes two working processes based on the type of gas to be processed;

[0101] The first working process: For Penning gas (easily ionizable gas), generally it can be excited and discharged at low power and low air pressure, which meets the applicable conditions of electron cyclotron resonance. The plasma excited by the electron cyclotron resonance microwave plasma mode itself has relatively high uniformity, and the efficiency of microwave coupling to the plasma is high. The plasma can be further regulated by adjusting the microwave power and air pressure; if there are still problems with uneven plasma discharge, further regulation can be carried out by coupling radio frequency plasma technology;

[0102] The second working process: For gases with high ionization energy, its excitation threshold is high, and a stronger electric field is required to break down the gas. Therefore, microwave plasma is used as the main excitation means. After the plasma is excited, the plasma discharge state can be adjusted by adjusting the microwave energy and power. If uneven discharge occurs, considering adding a radio frequency current to the coil to regulate the uniformity of the plasma and increase the dissociation degree of the plasma; if the plasma absorbs less microwave power, a direct current can be added to the coil, using the principle of electron cyclotron resonance to increase the energy efficiency of microwave coupling to the plasma.

[0103] Ultimately, this device aims to achieve a uniform, highly efficient, large-area, and effective plasma source under different gas pressure environments and raw material gas types.

Claims

1. A high-efficiency etching apparatus based on microwave ECR and radio frequency plasma coupling, comprising a cylindrical metal waveguide, an airflow inlet disposed at the upper end of the cylindrical metal waveguide, and an airflow outlet disposed at the lower end of the cylindrical metal waveguide, wherein the interior of the cylindrical metal waveguide is divided into an upper cavity and a lower etching region, characterized in that, A plurality of rectangular waveguides communicating with the inside of the cylindrical metal waveguide are evenly distributed on the outer wall of the cylindrical metal waveguide corresponding to the upper cavity, and a microwave input port communicating with a microwave source is provided at the end of each rectangular waveguide; A quartz cavity communicating with the air inlet is arranged in the upper cavity, and a coil wound around the outer wall of the quartz cavity, and both ends of the coil are connected to a DC power supply and / or a radio frequency power supply through wires, and the inside of the quartz cavity is a plasma discharge area; Both the cylindrical metal waveguide and the quartz cavity are cylindrical cavities, and the axes of the cylindrical metal waveguide and the quartz cavity coincide; The etching area is located below the quartz cavity, and an etching sample processing table for placing an etching sample and a pressing component for pressing the etching sample are arranged on the etching sample processing table in the etching area.

2. The high-efficiency etching apparatus based on microwave ECR and radio frequency plasma coupling according to claim 1, characterized in that, A tuning triple-pin device for regulating the microwave energy efficiency fed in is provided at each microwave input port.

3. The high-efficiency etching apparatus based on microwave ECR and radio frequency plasma coupling according to claim 2, characterized in that, The number of the rectangular waveguides is four, and the four rectangular waveguides are radially distributed in a circumferential direction on the outer wall of the cylindrical metal waveguide.

4. The high-efficiency etching apparatus based on microwave ECR and radio frequency plasma coupling according to claim 3, characterized in that, The microwave input powers of the four microwave input ports are the same. The four microwave input ports are sequentially divided into a first port, a second port, a third port and a fourth port. The phases of the first port and the third port are the same, the phases of the second port and the fourth port are the same, and the phase difference between the first port and the second port is 180°.

5. The high-efficiency etching apparatus based on microwave ECR and radio frequency plasma coupling according to claim 1, characterized in that, A mass flowmeter is arranged at the air inlet outside the quartz cavity.

6. A high-efficiency etching method based on microwave ECR and radio frequency plasma coupling, employing the high-efficiency etching equipment based on microwave ECR and radio frequency plasma coupling as described in any one of claims 1 to 5, characterized in that, The high-efficiency etching equipment has three single modes: a microwave plasma mode, an electron cyclotron resonance microwave plasma mode, and a radio frequency inductively coupled plasma mode; by controlling the type of current in the coil and taking the pressure of the gas to be processed as a criterion, the high-efficiency etching equipment selectively selects three different single modes; The first mode: when no current passes through the coil and the air pressure P>100 Pa, the microwave plasma mode is adopted; The second mode: when a DC current passes through the coil and the air pressure P<10 Pa, the electron cyclotron resonance microwave plasma mode is adopted; The third mode: when the microwave source is turned off, a radio frequency current passes through the coil, and the air pressure 1 Pa<P<100 Pa, the radio frequency inductively coupled plasma mode is adopted.

7. The high-efficiency etching method based on microwave ECR and radio frequency plasma coupling according to claim 6, characterized in that, The high-efficiency etching equipment proposes two working processes taking the type of the gas to be processed as a criterion; The first working process: for Penning gas, which meets the applicable conditions of electron cyclotron resonance, the plasma is further regulated by regulating the microwave power and air pressure; if there is still a problem of uneven plasma discharge, it is further regulated by coupling radio frequency plasma technology; The second working process: for gases with high ionization energy, microwave plasma is used as the main excitation means. After the plasma is excited, the plasma discharge state is adjusted by adjusting the microwave energy and power. If the discharge is uneven, a radio frequency current is added to the coil to regulate the uniformity of the plasma and increase the dissociation degree of the plasma; If the plasma absorbs little microwave power, add a DC current to the coil and use the principle of electron cyclotron resonance to increase the energy efficiency of microwave coupling to the plasma.

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