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

Abstract

The invention discloses an efficient etching method and device based on microwave ECR and radio frequency plasma coupling, and relates to the technical field of plasma etching.The device comprises a cylindrical metal waveguide tube, and the interior of the cylindrical metal waveguide tube is divided into an upper cavity on the upper portion and an etching area on the lower portion; a plurality of rectangular waveguide tubes communicated with the interior of the cylindrical metal waveguide tube are uniformly distributed on the outer wall of the cylindrical metal waveguide tube corresponding to the upper cavity, and the tail end of each rectangular waveguide tube is provided with a microwave input port communicated with a microwave source; a quartz cavity communicated with the airflow inlet and a coil wound on the outer wall of the quartz cavity are arranged in the upper cavity, the two ends of the coil are connected with a direct-current power supply and / or a radio-frequency power supply through wires, and a plasma discharge area is arranged in the quartz cavity. The electron cyclotron resonance technology and the radio frequency plasma inductive coupling technology are used for jointly regulating and controlling the microwave plasma, the energy conversion efficiency from microwaves to the plasma is improved, more uniform plasma can be generated, the etching area is remarkably increased, and efficient etching is achieved.

Description

Technical Field

[0001] The present invention relates to the field of plasma etching technology, and more specifically to the field of high-efficiency etching method and equipment technology based on microwave ECR and radio frequency plasma coupling. Background Art

[0002] Plasma technology is widely used in industrial processing, including semiconductor manufacturing, material surface treatment, cleaning, etching, etc. Plasma is composed of partially or fully ionized gas, including electrons, ions and neutral particles, which can be generated under high temperature or electromagnetic field. Plasma technology usually includes microwave plasma (MWP) technology, radio frequency inductively coupled plasma (ICP) technology and microwave electron cyclotron resonance (ECR) technology.

[0003] Microwave plasma (MWP) technology is an advanced processing technology that uses electromagnetic waves at microwave frequencies (2.45 GHz or 915 MHz) to excite the plasma state. The advantages of this technology include high ionization efficiency, no electrode pollution, and the ability to operate over a wide pressure range. Microwave plasma is particularly important in etching and thin film deposition processes because it can provide high-density plasma, thereby achieving higher processing speeds and better uniformity. However, the stability and efficiency of microwave plasma systems may be challenged when faced with different operating conditions (such as gas types, pressure changes, etc.).

[0004] Radio frequency inductively coupled plasma (ICP) technology forms and maintains plasma by generating a magnetic field in a coil using radio frequency current. ICP technology is characterized by the 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 sensitive to changes in equipment design and operating conditions.

[0005] Microwave electron cyclotron resonance (ECR) technology uses microwaves of a specific frequency to make electrons cyclotron in a magnetic field, thereby efficiently ionizing gas molecules to generate plasma. The advantage of ECR ​​is that it can work at a lower gas pressure and produce high-density and low-temperature plasma, which is ideal for processes that require fine control (such as microstructure etching). ECR plasma sources can provide a stable plasma flow, but require high precision control of the magnetic field.

[0006] The plasma generated by microwave plasma (MWP) technology has poor uniformity and is easy to etch the outer wall of the reaction chamber; microwave electron cyclotron resonance (ECR) technology is an extension of microwave plasma (MWP) technology, which improves the uniformity of plasma by constraining the electron motion trajectory through 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 is not robust enough. When conditions such as gas type, gas concentration, pressure, and input power change, the morphology of the plasma is prone to significant changes, resulting in a large change in the plasma's ability to absorb electromagnetic waves, which results in greater reflection and reduces the efficiency of microwave-to-plasma conversion. At the same time, existing equipment is sensitive to pressure and can generally only work in a specific pressure range, and cannot achieve plasma regulation under wide pressure conditions. Summary of the invention

[0008] The purpose of the present invention is to solve the technical problems of low efficiency of microwave to plasma conversion and poor plasma uniformity in existing microwave plasma cleaning and etching equipment. The present invention provides efficient etching equipment and methods based on microwave ECR and radio frequency plasma coupling. This scheme uses electron cyclotron resonance technology and radio frequency plasma inductive coupling technology to jointly control microwave plasma, which improves the energy conversion efficiency from microwave to plasma, and can produce a more uniform plasma, significantly increase the etching area, and achieve efficient etching. At the same time, the present invention improves the flexibility of plasma processing within a wider pressure range, and can achieve efficient and uniform excitation of different pressures and different raw gas. In addition, the device in this patent also has the advantage of a large adjustable parameter space, which can be adjusted according to the needs of the sample to be etched.

[0009] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0010] The first aspect of the present invention provides a high-efficiency etching device based on microwave ECR and radio frequency plasma coupling, comprising a cylindrical metal waveguide, an airflow inlet arranged at the upper end of the cylindrical metal waveguide and an airflow outlet arranged at the lower end of the cylindrical metal waveguide, the interior of the cylindrical metal waveguide is divided into an upper cavity at the upper part and an etching area at the lower part, a plurality of rectangular waveguides connected to the interior of the cylindrical metal waveguide are evenly distributed on the outer wall of the cylindrical metal waveguide corresponding to the upper cavity, and each rectangular waveguide is provided with a microwave input port connected to a microwave source at the end;

[0011] The upper cavity is provided with a quartz cavity connected with the airflow inlet and a coil wound on the outer wall of the quartz cavity. Both ends of the coil are connected with a DC power supply and / or a radio frequency power supply through a wire. The interior of the quartz cavity is a plasma discharge zone.

[0012] Specifically, if Figure 1 and Figure 2As shown, a coil is wound around the periphery of the quartz cavity. In addition to being able to load direct current or RF alternating current (generally 13.56MHz) at both ends of the coil, both currents can also be loaded simultaneously. Add an RF protection circuit to protect the DC power supply, and add a DC protection circuit to protect the RF power supply. There is also a cylindrical metal waveguide on the periphery of the quartz tube, and four BJ22 standard rectangular waveguides feed microwaves into the cylindrical waveguide. The vacuum quartz cavity is a plasma discharge zone, and the plasma is blown into the etching zone after it is generated.

[0013] The electric field distribution of the discharge area with and without the coil under no-load is as follows Figure 3 It is not difficult to find 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, the cylindrical metal waveguide and the quartz cavity are both cylindrical cavities, and the axis of the cylindrical metal waveguide coincides with the axis of the quartz cavity.

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

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

[0017] In one embodiment, the number of the rectangular waveguide tubes is four, and the four rectangular waveguide tubes are radially distributed on the outer wall of the cylindrical metal waveguide tube in a circumferential manner.

[0018] In one embodiment, 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 first port and the third port have the same phase, the second port and the fourth port have the same phase, and the phase difference between the first port and the second port is 180°.

[0019] Specifically, the microwave input powers of the four microwave input ports are the same, the first port and the third port have the same phase, the second port and the fourth port have the same 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 will also significantly affect the electromagnetic field distribution, and thus affect the uniformity and size of the plasma. In actual production, the input power and input phase of the electromagnetic field waves at the four ports can be changed according to the electromagnetic field simulation results, and the plasma can be controlled by regulating the electromagnetic waves.

[0021] In one embodiment, the etching area is located below the quartz chamber, and an etching sample processing table for placing the etching sample and a pressing component arranged on the etching sample processing table for pressing the etching sample are provided in the etching area.

[0022] Specifically, there is a pedestal 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 pedestal for picking up and placing the sample to be etched. There is a quartz pressing plate above the pedestal 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 shows 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 inlet 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 is used. The efficient etching equipment 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, and 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 make them generate 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.

[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 is used. The efficient etching equipment proposes two working processes based on the type of the gas to be processed as a criterion.

[0031] The first workflow: For Penning gas (easily ionized gas), it can usually be excited and discharged at 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 regulated by adjusting the microwave power and pressure. If the problem of uneven plasma discharge still exists, further regulation can be carried out through coupling radio frequency plasma technology.

[0032] The second working process: For gases with high ionization energy, the excitation threshold is high and a strong 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, consider adding RF current to the coil to regulate the uniformity of the plasma and increase the degree of dissociation of the plasma. If the plasma absorbs less microwave power, add DC current to the coil and use the principle of electron cyclotron resonance to increase the energy efficiency of microwave coupling to the plasma.

[0033] Ultimately, this device hopes to obtain a plasma source that is uniform, energy-efficient, has a large processing area, and has good processing effects under different gas pressure environments and types of raw gas.

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

[0035] 1. The present invention couples ECR technology with I CP technology, which can achieve better process control and higher energy efficiency by utilizing the low temperature characteristics of ECR ​​technology and the uniformity of I CP technology while maintaining high-density plasma. This coupling method can alleviate the instability of a single technology when facing changes in operating conditions.

[0036] 2. The present 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 can produce a more uniform plasma, significantly increase the etching area, and achieve efficient etching. At the same time, the present invention improves the flexibility of plasma processing within a wider pressure range, and can achieve efficient and uniform excitation of different pressures and different raw material gases.

[0037] 3. The device of the present invention also has the advantage of a large adjustable parameter space. According to the requirements of the sample to be etched, it can adjust ① the amplitude and phase of different microwave feeding ports; ② the amplitude of the DC current; ③ the amplitude and frequency of the RF current; ④ the flow rate of the raw gas; ⑤ the pressure in the reaction chamber; ⑥ the height of the etching sample stage, thereby exciting and generating plasmas of different types and sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

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

[0040] Figure 2 yes Figure 1 A local three-dimensional image of .

[0041] Figure 3 This is a simulation diagram comparing the electric field of the etching equipment with and without a coil.

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

[0043] Figure 5 It is a simulation flow chart of the discharge process of plasma under the action of magnetic field.

[0044] Figure 6 This is a simulation diagram of the regulating effect on plasma after adding RF 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] Fig. 9 This is a simulation diagram of the electron temperature distribution under different input powers.

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

[0049] Fig.11 is a diagram of the energy efficiency of microwave coupling into plasma at different input powers.

[0050] Fig.12 This is a simulation diagram of the electric field strength under different RF currents.

[0051] Fig.13 This is a simulation diagram of electron temperature under different RF currents.

[0052] Fig.14 is a diagram of the energy efficiency of microwave coupling to plasma under different RF currents.

[0053] Fig.15 It is a flow chart of three single mode excitation methods.

[0054] Fig.16 It is a flow chart of plasma excitation by coupling microwave electron cyclotron resonance and radio frequency plasma. DETAILED DESCRIPTION

[0055] In order to make the technical problems, technical solutions and technical effects of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0057] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0058] In the description of the embodiments of the present invention, it should be noted that the terms "inside", "outside", "upper", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. 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, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0059] Example 1

[0060] The present embodiment provides a high-efficiency etching device based on microwave ECR and radio frequency plasma coupling, comprising a cylindrical metal waveguide, an airflow inlet arranged at the upper end of the cylindrical metal waveguide, and an airflow outlet arranged at the lower end of the cylindrical metal waveguide, the interior of the cylindrical metal waveguide is divided into an upper cavity at the upper part and an etching area at the lower part, a plurality of rectangular waveguides connected to the interior of the cylindrical metal waveguide are evenly distributed on the outer wall of the cylindrical metal waveguide corresponding to the upper cavity, and each rectangular waveguide is provided with a microwave input port connected to a microwave source at the end;

[0061] The upper cavity is provided with a quartz cavity connected with the airflow inlet and a coil wound on the outer wall of the quartz cavity. Both ends of the coil are connected with a DC power supply and / or a radio frequency power supply through a wire. The interior of the quartz cavity is a plasma discharge zone.

[0062] Specifically, if Figure 1 and Figure 2 As shown, a coil is wound around the periphery of the quartz cavity. In addition to being able to load direct current or RF alternating current (generally 13.56MHz) at both ends of the coil, both currents can also be loaded simultaneously. Add an RF protection circuit to protect the DC power supply, and add a DC protection circuit to protect the RF power supply. There is also a cylindrical metal waveguide on the periphery of the quartz tube, and four BJ22 standard rectangular waveguides feed microwaves into the cylindrical waveguide. The vacuum quartz cavity is a plasma discharge zone, and the plasma is blown into the etching zone after it is generated.

[0063] The electric field distribution of the discharge area with and without the coil under no-load is as follows Figure 3 It is not difficult to find that after adding the coil, the electric field is more concentrated in the discharge cavity and the electric field distribution is more uniform.

[0064] The cylindrical metal waveguide and the quartz cavity are both cylindrical cavities, and the axis of the cylindrical metal waveguide coincides with the axis of the quartz cavity.

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

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

[0067] The number of the rectangular waveguide tubes is four, and the four rectangular waveguide tubes are radially distributed on the outer wall of the cylindrical metal waveguide tube in a circumferential manner.

[0068] 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 first port and the third port have the same phase, the second port and the fourth port have the same phase, and the phase difference between the first port and the second port is 180°.

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

[0070] The etching area is located below the quartz cavity. An etching sample processing table for placing etching samples and a pressing component arranged on the etching sample processing table for pressing the etching samples are arranged in the etching area.

[0071] Specifically, there is a base in this area for placing the sample to be etched, and a quartz pressure plate is placed above the base to fix the sample. The entire device is pumped from the bottom to maintain its low-pressure environment. Figure 2 The dashed line shows the direction of air flow.

[0072] A mass flow meter is arranged at the air flow inlet outside 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] Study the effect of the number of coil turns on the central field strength of the plasma discharge area:

[0075] After microwaves are fed from the four microwave input ports, a strong electric field is generated in the center of the plasma discharge area, which is then excited to generate 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 Effect of coil turns on the central field strength of plasma discharge area

[0077] Coil turns (turns) Maximum central electric field strength (V / m) 8 <![CDATA[1.76×10 4 ]]> 12 <![CDATA[4.7×10 4 ]]> 16 <![CDATA[1.6×10 4 ]]> 20 <![CDATA[1.8×10 4 ]]>

[0078] The study found that the appropriate number of coil turns is conducive to electric field focusing and helps to excite plasma. When the number of coil turns is 12, the central field strength can reach up to 4.7×104 (V / m). Adding coils is conducive to focusing the central field strength.

[0079] The coil is evenly wound around the quartz tube, and the number of turns of the coil and the current passing through are set to control the magnetic field, including direct current (DC) current and radio frequency (RF) current, so as to regulate the plasma. In the simulation, only the current size of the coil is reflected, and the distinction between DC and RF is not considered. The current in the coil is set to 14.5A, and the magnetic flux density is as follows Figure 4 shown.

[0080] exist Figure 4 A magnetic flux density is generated from bottom to top, which can be used to regulate the plasma discharge process. The magnetic flux density is consistent with the actual distribution.

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

[0082] like Figure 6 As shown in the figure, when there is no RF current, the electron density is concentrated in the middle of the discharge region. Figure 4After the unidirectional coupling simulation of the RF current shown in the figure, the plasma spreads in the entire discharge area and is more concentrated at the edge close to the quartz wall. The process of adding RF current reflects the regulation of the plasma. As the RF current gradually increases, the plasma tends to gather from the center to the edge. The arrows in the simulation diagram are diffuse electron fluxes. When there is no current, the plasma shows a divergent distribution characteristic from the center to the edge. After adding RF current, the electron diffusion flux is distributed along the Figure 4 The magnetic flux direction distribution is shown in Figure 1, and the plasma range is larger. The simulation results show that adding a magnetic field can effectively improve the uniformity of microwave plasma and increase the discharge area of ​​plasma.

[0083] Study the effects of different RF currents and microwave powers on plasma:

[0084] Changing the microwave input power will cause significant changes in the parameters of the plasma. Under different input powers (400W, 600W, 800W, 1000W), the electric field distribution in the device is as follows Figure 7 shown.

[0085] It is not difficult to find that at a lower input power, the plasma cannot be excited well, and the electric field can penetrate the plasma and gather in the quartz cavity. As the power increases, the position close to the microwave feed port is excited first and produces a sheath. As the input power increases, the rear sheath surrounding the plasma is further stabilized. The area corresponding to the sheath is also the area where the plasma electron density is concentrated, as shown below Figure 8 shown.

[0086] Figure 8 The black line in the middle is the electron density of 7.6×1016 (1 / m 3 ) is the critical electron density for plasma excitation at 2.45 GHz. It can be considered that the area within the isoline range is the plasma region. It is not difficult to find that with the increase of power, the isoline area expands significantly, the central electron density also increases further, and the plasma region covers a wide range.

[0087] In plasma, electron temperature is a physical quantity that describes the intensity of electron thermal motion. Electrons in plasma gain energy under the influence of electric fields, magnetic fields, and collisions between particles, thereby performing thermal motion. The electron temperature in this model is as follows: Fig. 9 shown.

[0088] Gas temperature is a physical quantity that characterizes the intensity of thermal motion of heavy particles (such as atoms, molecules, etc.) in plasma. Gas temperature is mainly determined by collisions between heavy particles and their energy exchange with the environment. In plasma, heavy particles will constantly collide with each other, transfer energy through collisions, and thus reach a thermal equilibrium state. The intensity of thermal motion in this equilibrium state is measured by gas temperature. The gas temperature in this model increases significantly with increasing power, as shown below Fig.10 shown.

[0089] Changing the input power can also have a significant effect on the energy efficiency of microwave coupling to the plasma, as follows Fig.11 As shown in the figure, as the power continues to increase from 450 W, the energy efficiency shows a trend of first increasing and then decreasing. When the input power is 800 W, the energy efficiency is the highest, reaching 95%. Subsequently, as the power further increases, the energy efficiency decreases slightly, reflecting the regulatory effect of changes in input power on plasma.

[0090] Keep the total power at 1000W and calculate the effect of different currents on the electron density. Fig.12 As shown, when the RF current is low, the plasma is not completely excited above the reaction chamber, so the sheath generated above is irregular. As the RF current increases, the plasma above is completely excited, and the field strength above also shows TEM distribution characteristics.

[0091] Fig.13 Demonstrated the regulation of electron temperature by RF current.

[0092] Changing the current also has a significant effect 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%. 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 in Fig.14 shown.

[0093] Example 2

[0094] like Fig.15 As shown, this embodiment provides an efficient etching method based on microwave ECR and radio frequency plasma coupling, using the above-mentioned efficient etching equipment based on microwave ECR and radio frequency plasma coupling, the efficient etching equipment 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 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, and the electron density is high. However, when the power is relatively 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. However, 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 Fig.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, their 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, adding a radio frequency current to the coil can be considered 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, and using the principle of electron cyclotron resonance, the energy efficiency of microwave coupling to the plasma can be increased.

[0103] Ultimately, this device hopes to obtain a plasma source that is uniform, energy-efficient, has a large processing area, and has good processing effects under different gas pressure environments and types of raw gas.

Claims

1. A high-efficiency etching device based on microwave ECR and radio frequency plasma coupling, comprising a cylindrical metal waveguide, an airflow inlet arranged at the upper end of the cylindrical metal waveguide and an airflow outlet arranged at the lower end of the cylindrical metal waveguide, wherein the interior of the cylindrical metal waveguide is divided into an upper cavity at the upper part and an etching area at the lower part, characterized in that: A plurality of rectangular waveguides communicating with the inside of the cylindrical metal waveguide are uniformly distributed on the outer wall of the cylindrical metal waveguide corresponding to the upper cavity, and microwave input ports communicating with a microwave source are arranged at the ends of the rectangular waveguides. A quartz cavity communicating with the gas 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 an RF power supply through wires, and the inside of the quartz cavity is a plasma discharge region.

2. The high-efficiency etching equipment based on microwave ECR and radio frequency plasma coupling according to claim 1 is characterized in that: 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.

3. The high-efficiency etching equipment based on microwave ECR and radio frequency plasma coupling according to claim 1 is characterized in that: Each of the microwave input ports is provided with a tuning triple-pin device for regulating the microwave energy efficiency fed in.

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

5. The high-efficiency etching equipment based on microwave ECR and radio frequency plasma coupling according to claim 4 is 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°.

6. The high-efficiency etching equipment based on microwave ECR and radio frequency plasma coupling according to claim 1 is characterized in that: The etching region is located below the quartz cavity. An etching sample processing table for placing an etching sample and a pressing assembly for pressing the etching sample are arranged on the etching sample processing table.

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

8. A high-efficiency etching method based on microwave ECR and radio frequency plasma coupling, using a high-efficiency etching device based on microwave ECR and radio frequency plasma coupling as claimed in any one of claims 1 to 7, 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 using 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, an RF current passes through the coil, and the air pressure 1 Pa < P < 100 Pa, the radio frequency inductively coupled plasma mode is adopted.

9. The high-efficiency etching method based on microwave ECR and radio frequency plasma coupling according to claim 8, characterized in that: The high-efficiency etching equipment proposes two working processes based on the type of the gas to be processed. The first working process: for Penning gas, which meets the applicable conditions of electron cyclotron resonance, the plasma is further regulated by controlling the microwave power and the 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, the 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 the discharge is uneven, an RF 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 less microwave power, a 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.

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