Capacitively coupled plasma processing apparatus

Abstract

The disclosure provides a capacitive coupling plasma processing device, comprising a housing, a first electrode, a second electrode, a first radio frequency bias source and a second radio frequency bias source, the housing has a receiving cavity, the first electrode and the second electrode are located in the receiving cavity and are at least partially oppositely arranged, and a to-be-processed piece is located on the side of the first electrode facing the second electrode; the first radio frequency bias source is electrically connected with the first electrode, the second radio frequency bias source is electrically connected with the second electrode, the frequency of the first radio frequency bias source and the second radio frequency bias source is equal, and the interval is half a period. The second radio frequency bias source can hinder the movement of electrons towards the second electrode, hinder the formation of the electron sheath near the second electrode, reduce the attraction of the electron sheath to the positive ions, and improve the movement speed of the positive ions towards the first electrode. Therefore, the capacitive coupling plasma processing device provided by the disclosure can improve the bombardment ability of the positive ions in the plasma to the to-be-processed piece, thereby improving the etching effect on the to-be-processed piece.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a capacitively coupled plasma processing device. Background Art

[0002] Plasma processing has been widely used in the semiconductor industry and other industrial fields. Plasma processing is used in semiconductor process steps such as cleaning, etching, and deposition.

[0003] In related art, a capacitively coupled plasma processing apparatus may include a processing chamber, an upper plate, and a lower plate disposed opposite each other. The upper plate and the lower plate are both located within the processing chamber. A processing gas is introduced between the upper and lower plates, and a radio frequency power source is applied to one of the upper and lower plates. This radio frequency power source excites the processing gas within the processing chamber, causing the processing gas to form a plasma. This plasma then bombards the material on the wafer surface, breaking chemical bonds therein and reacting with the plasma to generate volatile substances. These substances, in the form of gases, separate from the wafer surface and are discharged outside the processing chamber, completing the etching process.

[0004] However, the cations in the plasma have a weak bombardment capability on the wafer, thereby affecting the etching effect of the wafer. Summary of the Invention

[0005] The embodiments of the present disclosure provide a capacitively coupled plasma processing apparatus, which can improve the bombardment capability of cations in the plasma on a workpiece to be processed, thereby improving the etching effect on the workpiece to be processed.

[0006] The embodiments of the present disclosure provide the following technical solutions:

[0007] An embodiment of the present disclosure provides a capacitively coupled plasma processing device, comprising a shell, a first electrode, a second electrode, a first RF bias source, and a second RF bias source. The shell has a receiving cavity, the first electrode and the second electrode are both located in the receiving cavity and are at least partially arranged opposite to each other, and the workpiece to be processed is located on the side of the first electrode facing the second electrode; the first RF bias source is electrically connected to the first electrode, and the second RF bias source is electrically connected to the second electrode. The frequencies of the first RF bias source and the second RF bias source are equal and are separated by half a cycle.

[0008] The capacitively coupled plasma processing device provided by the embodiment of the present disclosure may include a shell, a first electrode, a second electrode, a first RF bias source and a second RF bias source, the shell having a receiving cavity, the first electrode and the second electrode both being located in the receiving cavity and at least partially arranged relative to each other. The shell forms a protection for the first electrode and the second electrode. The workpiece to be processed is located on the side of the first electrode facing the second electrode, the first RF bias source is electrically connected to the first electrode, thereby providing a negative potential to the first electrode to form an ion sheath layer near the first electrode to increase the movement speed of the cations, thereby making the bombardment ability of the cations on the workpiece to be processed stronger, which is conducive to improving the etching effect of the workpiece to be processed. The second RF bias source is electrically connected to the second electrode, and the frequencies of the first RF bias source and the second RF bias source are equal and spaced half a cycle apart. The second RF bias source can hinder the movement of electrons toward the second electrode, thereby hindering the formation of an electron sheath near the second electrode, reducing the attraction of the electron sheath to the cations, increasing the movement speed of the cations toward the first electrode, thereby increasing the bombardment ability of the cations on the workpiece to be processed (for example, a wafer), and improving the etching effect of the workpiece to be processed.

[0009] In one possible embodiment, a capacitively coupled plasma processing apparatus includes a power converter and a radio frequency bias source, wherein an input end of the power converter is connected to the radio frequency bias source, a first output end of the power converter is electrically connected to a first electrode to form a first radio frequency bias source, and a second output end of the power converter is electrically connected to a second electrode to form a second radio frequency bias source.

[0010] The power converter can be used to distribute the radio frequency power generated by the radio frequency bias source to the first electrode and the second electrode. The power converter can be used to synchronously adjust the power distribution of the first electrode and the second electrode, thereby better controlling the movement of electrons.

[0011] In a possible implementation, the capacitively coupled plasma processing apparatus further includes a radio frequency excitation source electrically connected to the first electrode, and a frequency of the radio frequency excitation source is greater than a frequency of the first radio frequency bias source.

[0012] In a possible implementation, the radio frequency excitation source is a pulse power supply, which alternately outputs at least two pulse signals, and the duty cycles of the at least two pulse signals are different.

[0013] By setting a plurality of pulse signals with different duty cycles, different etching morphologies can be formed.

[0014] In a possible implementation, the at least two pulse signals include a first pulse signal and a second pulse signal, and a duty cycle of the first pulse signal is smaller than a duty cycle of the second pulse signal.

[0015] The coordinated operation of two RF working modes, namely the alternating first pulse signal and the second pulse signal, is beneficial to increasing the control over the etching morphology. While ensuring the etching morphology with a high aspect ratio, it does not affect the separation of etching by-products from the surface of the workpiece to be processed.

[0016] In a possible implementation, the power of the first pulse signal is less than the power of the second pulse signal.

[0017] In a possible implementation, a duty cycle of the first pulse signal is less than or equal to 1 / 2.

[0018] The pulse off time of the first pulse signal can be ensured to be longer, thereby facilitating the separation of etching by-products from the surface of the workpiece to be processed.

[0019] In a possible implementation manner, a duty cycle of the second pulse signal is greater than or equal to 3 / 4.

[0020] The pulse on time of the second pulse signal can be ensured to be longer, thereby being beneficial to improving etching efficiency and being beneficial to etching a high aspect ratio feature.

[0021] In a possible implementation manner, the first pulse signal and the second pulse signal have different frequencies.

[0022] Etching byproducts can be promptly removed, resulting in a cleaner surface for the workpiece. This reduces or prevents the deposition of etching byproducts on the workpiece surface, preventing the plasma from etching the underlying film structure, thereby reducing or preventing any impact on the subsequent etching process. Furthermore, the frequency of the two pulse signals can be adjusted to adjust etching uniformity, resulting in more uniform features on the workpiece surface.

[0023] In a possible embodiment, the capacitively coupled plasma processing apparatus further includes a capacitor, and a capacitor is provided between at least one of the first electrode and the RF excitation source, between the first electrode and the first RF bias source, and between the second electrode and the second RF bias source.

[0024] Capacitors cannot allow direct current to pass through, but they can allow alternating current to pass through.

[0025] In a possible embodiment, the capacitively coupled plasma processing apparatus further includes an impedance matcher, and an impedance matcher is provided between at least one of the first electrode and the RF excitation source, between the first electrode and the first RF bias source, and between the second electrode and the second RF bias source.

[0026] Impedance matching box can improve the efficiency of feeding

[0027] In a possible embodiment, the capacitively coupled plasma processing device further includes a carrier, which is located in the accommodating cavity and is located on the side of the first electrode facing the second electrode. The side of the carrier facing the second electrode has a carrying surface, and the part to be processed is located on the carrying surface.

[0028] The carrier may protect the first electrode.

[0029] In a possible implementation, the capacitively coupled plasma processing apparatus further includes a focus ring, which is disposed on the periphery of the carrying surface.

[0030] The focus ring can be used to ensure etching uniformity of the entire workpiece to be processed, thereby reducing structural differences of semiconductor devices formed on the workpiece to be processed and increasing etching yield.

[0031] In a possible implementation manner, the first electrode and the second electrode extend in the same direction.

[0032] The first electrode and the second electrode have simple shapes and low cost.

[0033] In a possible embodiment, the second electrode includes a first extension portion and a second extension portion connected to each other. The first extension portion is arranged opposite to the first electrode and extends in the same direction. The second extension portion is located at an edge of the first extension portion and extends toward the first electrode.

[0034] In one possible implementation, the capacitively coupled plasma processing apparatus includes a capacitively coupled plasma etching apparatus.

[0035] Capacitively coupled plasma etching equipment can etch features with high aspect ratios.

[0036] The configuration of the present disclosure and other inventive objects and advantageous effects thereof will become more apparent through the description of preferred embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 A schematic structural diagram of placing a workpiece to be processed in a capacitively coupled plasma processing device according to an embodiment of the present disclosure;

[0039] Figure 2 A schematic structural diagram of a first electrode and a second electrode provided in an embodiment of the present disclosure;

[0040] Figure 3 Another schematic structural diagram of the first electrode and the second electrode provided in an embodiment of the present disclosure;

[0041] Figure 4 A sinusoidal waveform diagram of a first radio frequency bias source provided in an embodiment of the present disclosure;

[0042] Figure 5 A sinusoidal waveform diagram of a second RF bias source provided in an embodiment of the present disclosure;

[0043] Figure 6 A schematic diagram of the structure of a capacitively coupled plasma processing device provided in an embodiment of the present disclosure, which is provided with a radio frequency bias source and a power converter;

[0044] Figure 7 This is a pulse waveform diagram of the radio frequency excitation source provided in an embodiment of the present disclosure.

[0045] Description of reference numerals:

[0046] 110: housing; 111: accommodating cavity; 112: air inlet;

[0047] 113: exhaust hole; 121: air source; 122: vacuum pump;

[0048] 131: first electrode; 132: second electrode; 1321: first extension portion;

[0049] 1322: second extension portion; 141: base; 142: supporting member;

[0050] 1421: bearing surface; 143: focusing ring; 151: first RF bias source;

[0051] 152: second RF bias source; 153: RF bias source; 154: RF excitation source;

[0052] 155: power converter; 156: impedance matching device; 157: capacitor;

[0053] 200: Pending items. DETAILED DESCRIPTION

[0054] In related art, a capacitively coupled plasma processing apparatus may include a processing chamber, an upper plate, and a lower plate disposed opposite each other, both located within the processing chamber. High-frequency AC power is applied to the lower plate to excite a processing gas within the processing chamber, causing it to dissociate into electrons, ions, and free radicals to form a plasma. This plasma is then used to bombard material on the wafer surface, thereby etching the material.

[0055] Because the mass of electrons in the plasma is much smaller than that of cations, their velocity is much greater than that of cations. Consequently, electrons first accumulate on the lower plate, giving it a negative potential. This negative potential repels subsequent electrons while simultaneously attracting cations until the negative potential of the lower plate reaches a certain value, where the electron flow equals the cation flow. Due to the negative potential of the lower plate, a space charge layer composed of cations forms near it, known as the ion sheath. A low-frequency alternating current can be applied to the lower plate to replenish electrons and maintain its negative potential. The electric field of the ion sheath accelerates the cations toward the wafer on the lower plate, increasing their impact and facilitating etching.

[0056] However, the upper plate can be grounded, and the electrons of the upper plate can be led to the earth, so that the upper plate appears the gathering of cationic species, the upper plate will attract electrons and repel cationic species, and finally form a space charge layer, i.e., an electron sheath, constructed by electrons near the upper plate. The electron sheath can attract cationic species to move toward the upper plate, thereby hindering the movement of cationic species toward the lower plate, causing the bombardment ability of cationic species to the wafer on the lower plate to be less than 0.05, hindering etching, thereby affecting the etching effect of wafer. For example, in the process of preparing the capacitor of dynamic random access memory (DRAM), if the bombardment ability of cationic species is less than 0.05, the etching effect is poor, then higher aspect ratio cannot be obtained, thereby affecting the capacity of DRAM.

[0057] The present disclosure provides a capacitively coupled plasma processing device, which may include a shell, a first electrode, a second electrode, a first RF bias source, and a second RF bias source. The shell has a receiving cavity, and the first electrode and the second electrode are both located in the receiving cavity and are at least partially arranged opposite each other. The shell forms a protection for the first electrode and the second electrode. The workpiece to be processed is located on the side of the first electrode facing the second electrode. The first RF bias source is electrically connected to the first electrode, thereby providing a negative potential to the first electrode to form an ion sheath layer near the first electrode to increase the movement speed of the cations, thereby making the cations have a stronger bombardment ability on the workpiece to be processed, which is conducive to improving the etching effect of the workpiece to be processed. The second RF bias source is electrically connected to the second electrode, and the frequencies of the first RF bias source and the second RF bias source are equal and spaced half a cycle apart. The second RF bias source can hinder the movement of electrons toward the second electrode, thereby hindering the formation of an electron sheath near the second electrode, reducing the attraction of the electron sheath to the cations, and increasing the movement speed of the cations toward the first electrode, thereby increasing the bombardment ability of the cations on the workpiece to be processed (for example, a wafer), and improving the etching effect on the workpiece to be processed.

[0058] To make the objectives, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present disclosure without making any creative efforts shall fall within the scope of protection of the present disclosure.

[0059] The following will be combined Figure 1-Figure 7 The capacitively coupled plasma processing apparatus provided by an embodiment of the present disclosure is described.

[0060] The present disclosure provides a capacitively coupled plasma processing apparatus that can be used to perform plasma processing on a workpiece 200. The plasma processing may include, but is not limited to, doping, deposition, cleaning, and etching. The workpiece 200 may include a wafer or other structural parts to be processed.

[0061] The embodiments of the present disclosure are described by taking a capacitively coupled plasma processing apparatus for etching as an example.

[0062] The capacitively coupled plasma processing apparatus may include a capacitively coupled plasma etching apparatus. Figure 1 The capacitively coupled plasma processing apparatus may include a housing 110, which encloses a receiving chamber 111. The workpiece 200 may be processed in the receiving chamber 111 to avoid being affected by the external environment.

[0063] The housing 110's chamber 111 is connected to an external gas source 121, which is used to supply processing gas to the chamber 111. The housing 110 is provided with a gas inlet 112, through which the gas source 121 inputs processing gas into the chamber 111. A flow controller may be provided between the gas source 121 and the gas inlet 112 to control the flow rate of the gas input into the chamber 111. The capacitively coupled plasma processing apparatus may include a pressure detector for detecting the pressure in the chamber 111.

[0064] In addition, the housing 110 may be provided with an exhaust hole 113, which is connected to an external vacuum pump 122. The vacuum pump 122 is used to exhaust the gas in the accommodating chamber 111. An exhaust valve may be provided between the vacuum pump 122 and the exhaust hole 113 to control the exhaust rate of the gas in the accommodating chamber 111.

[0065] The capacitively coupled plasma processing apparatus may include a gas pressure controller for controlling the gas pressure in the accommodating chamber 111. The gas pressure controller may be electrically connected to at least one of a pressure detector, a flow controller, and an exhaust valve. The disclosed embodiment is described using an example in which the gas pressure controller is electrically connected to the pressure detector, the flow controller, and the exhaust valve. The gas pressure controller may obtain the pressure in the accommodating chamber 111 measured by the pressure detector and control the gas pressure in the accommodating chamber 111 to maintain a desired pressure value through the exhaust valve and the flow controller.

[0066] The first electrode 131 and the second electrode 132 provided by the embodiment of the present disclosure are described below.

[0067] See also Figure 1 The first electrode 131 and the second electrode 132 may be disposed in the accommodating cavity 111. The first electrode 131 and the second electrode 132 may be formed of a conductive material. The first electrode 131 and the second electrode 132 may be disposed at least partially opposite to each other.

[0068] For example, the first electrode 131 and the second electrode 132 may be arranged at least partially opposite to each other along the thickness direction of the housing 110. The first electrode 131 may be a lower electrode, the first electrode 131 may be arranged near the bottom of the housing 110, the first electrode 131 may be used to support the workpiece 200, and the workpiece 200 may be located on the side of the first electrode 131 facing the second electrode 132 (equivalent to Figure 1 The second electrode 132 may be an upper electrode, and the portion of the second electrode 132 opposite to the first electrode 131 may be disposed near the top of the housing 110. The region between the first electrode 131 and the second electrode 132 may be a region where plasma is generated.

[0069] The side of the first electrode 131 facing away from the second electrode 132 can be directly connected to the housing 110, thereby making the structure of the capacitively coupled plasma processing device relatively simple. Figure 1 A base 141 may be provided in the accommodating cavity 111. The base 141 is located on a side of the first electrode 131 away from the second electrode 132 (equivalent to Figure 1 The base 141 is located between the first electrode 131 and the bottom wall of the housing 110. For example, the base 141 may be formed of an insulating material.

[0070] A carrier 142 may be disposed within the accommodating cavity 111. The carrier 142 is located on the side of the first electrode 131 facing the second electrode 132. The side of the carrier 142 facing the second electrode 132 may have a carrier surface 1421, and the workpiece 200 may be located on the carrier surface 1421. In other words, the first electrode 131 may support the workpiece 200 via the carrier 142. The carrier 142 separates the first electrode 131 from the workpiece 200, thereby protecting the first electrode 131. The workpiece 200 may be secured to the carrier surface 1421 of the carrier 142 using static electricity, vacuum, or mechanical force.

[0071] Taking electrostatic adsorption of the workpiece 200 as an example, the support member 142 may be an electrostatic chuck. The electrostatic chuck may be formed of an insulating material and provided with a holding electrode, which may be connected to a DC power supply. The electrostatic chuck utilizes the Coulomb force generated by the DC voltage applied to the holding electrode by the DC power supply to hold the workpiece 200 on the support surface 1421.

[0072] See also Figure 1 A focusing ring 143 may be disposed in the accommodating cavity 111. The focusing ring 143 is disposed around the outer periphery of the supporting surface 1421 so that the focusing ring 143 surrounds the outer periphery of the workpiece 200. During the etching process, the focusing ring 143 can be used to direct at least a portion of the plasma toward the workpiece 200, thereby focusing the plasma on the workpiece 200. Furthermore, the focusing ring 143 can be used to ensure etching uniformity across the entire workpiece 200, thereby reducing structural variations in semiconductor devices formed on the workpiece 200 and increasing etching yield. The material of the focusing ring 143 may include at least one conductive material such as silicon or carbon. The focusing ring 143 may be annular. For example, the focusing ring 143 may be located on the side of the first electrode 131 facing the second electrode 132. The focusing ring 143 may be disposed around the outer periphery of the supporting surface 142, with the surface of the focusing ring 143 facing the second electrode 132 being higher than the surface of the supporting surface 142 or the workpiece 200 facing the second electrode 132.

[0073] For some examples, see Figure 2 , the extension direction of the first electrode 131 and the second electrode 132 can be the same, which is equivalent to the first electrode 131 and the second electrode 132 being parallel to each other. In this way, the structure of the first electrode 131 and the second electrode 132 is relatively simple. The embodiment of the present disclosure does not limit the relative arrangement area of ​​the first electrode 131 and the second electrode 132, the area of ​​the first electrode 131, and the area of ​​the second electrode 132. In other examples, see Figure 3The second electrode 132 may include a first extension portion 1321 and a second extension portion 1322. The first extension portion 1321 is arranged opposite the first electrode 131 and extends in the same direction, that is, the first extension portion 1321 and the first electrode 131 are parallel to each other. The second extension portion 1322 is located at the edge of the first extension portion 1321 and extends toward the first electrode 131, that is, the second extension portion 1322 is located on the side of the first extension portion 1321 closest to the first electrode 131. The second extension portion 1322 may be located at least partially along the edge of the first extension portion 1321. The orthographic projection of the first extension portion 1321 on the plane where the first electrode 131 is located may be a polygon (e.g., a rectangle), a circle, an ellipse, etc. The embodiment of the present disclosure does not limit the shape of the orthographic projection of the first extension portion 1321. For example, if the orthographic projection of the first extension portion 1321 on the plane where the first electrode 131 is located is a rectangle, the edge of the first extension portion 1321 may include four sides connected end to end, and the second extension portion 1322 may be located on any one or more of the four sides. For example, there may be two second extension portions 1322 , and the two second extension portions 1322 are respectively located on two opposite side edges.

[0074] See also Figure 1 The capacitively coupled plasma processing apparatus may further include a radio frequency excitation source 154, which may be electrically connected to the first electrode 131. For example, the radio frequency excitation source 154 may be a high-frequency power generator. The radio frequency excitation source 154 may be configured to excite the process gas between the first electrode 131 and the second electrode 132 into a plasma. The radio frequency excitation source 154 may be configured to provide alternating current to the first electrode 131. For example, the frequency of the radio frequency excitation source 154 may be 100 MHz.

[0075] For example, an impedance matcher 156 may be electrically connected between the RF excitation source 154 and the first electrode 131. Impedance matcher 156 can improve the efficiency of the feed. Alternatively, a capacitor 157 may be electrically connected between the RF excitation source 154 and the first electrode 131. Capacitor 157 does not allow direct current to pass through, but allows alternating current to pass through. Alternatively, an impedance matcher 156 and capacitor 157 may be electrically connected between the RF excitation source 154 and the first electrode 131, with capacitor 157 located between the first electrode 131 and impedance matcher 156.

[0076] See also Figure 1The capacitively coupled plasma processing apparatus may further include a first RF bias source 151, which may be electrically connected to the first electrode 131. The first RF bias source 151 may be used to provide a negative potential to the first electrode 131 to form an ion sheath near the first electrode 131 to increase the movement speed of the cations, thereby making the cations have a stronger bombardment ability on the workpiece 200, which is beneficial to improving the etching effect of the workpiece 200. By controlling the first RF bias source 151, the ability of the cations to bombard the workpiece 200 may be controlled. The first RF bias source 151 may be used to provide alternating current to the first electrode 131. For example, the frequency of the first RF bias source 151 may be 13 MHz. The frequency of the RF excitation source 154 may be greater than the frequency of the first RF bias source 151. The waveform of the first RF bias source 151 may be a sine wave.

[0077] For example, an impedance matcher 156 may be electrically connected between the first RF bias source 151 and the first electrode 131. Impedance matcher 156 can improve feeding efficiency. Alternatively, a capacitor 157 may be electrically connected between the first RF bias source 151 and the first electrode 131. Capacitor 157 does not allow direct current to pass through, but allows alternating current to pass through. Alternatively, an impedance matcher 156 and capacitor 157 may be electrically connected between the first RF bias source 151 and the first electrode 131, with capacitor 157 located between the first electrode 131 and impedance matcher 156.

[0078] See also Figure 1 The capacitively coupled plasma processing apparatus may further include a second RF bias source 152, which may be electrically connected to the second electrode 132. The waveform of the second RF bias source 152 may be a sine wave. Figure 4 shows a waveform diagram of the first RF bias source 151, Figure 5 : shows the waveform of the second RF bias source 152. The frequencies of the first RF bias source 151 and the second RF bias source 152 can be equal and separated by half a cycle. Figure 4 and Figure 5 The horizontal axis can represent time (t), and the vertical axis can represent the amplitude (v) of the signal (for example, current, voltage, etc.).

[0079] On the one hand, when the first RF bias source 151 outputs a positive voltage, the second RF bias source 152 outputs a negative voltage, causing electrons to be attracted by the positive voltage of the first electrode 131 and repelled by the negative voltage of the second electrode 132, thereby hindering the movement of electrons toward the second electrode 132, thereby hindering the formation of an electron sheath near the second electrode 132 and reducing the attraction of the electron sheath to cations. In addition, the electrons can be accelerated toward the first electrode 131, which is beneficial for the movement of electrons toward the first electrode 131, providing a negative potential for the first electrode 131, and facilitating the formation of an ion sheath layer near the first electrode 131, thereby increasing the movement speed of the cations, thereby increasing the bombardment ability of the cations on the workpiece 200, and improving the etching effect of the workpiece 200. In addition, the bombardment ability of the electrons on the workpiece 200 can be improved, thereby reducing the etching byproducts adsorbed on the surface of the workpiece 200, thereby reducing the impact of these etching byproducts on the etching process. If the bombardment power of the cations is small, they may be adsorbed on the surface of the workpiece 200 to be processed. Electrons with high bombardment power can reduce the cations adsorbed on the surface of the workpiece 200 to be processed, thereby reducing the impact of these cations on etching.

[0080] On the other hand, when the first RF bias source 151 outputs a negative voltage, the second RF bias source 152 outputs a positive voltage. This causes the cations to be attracted by the negative pressure of the first electrode 131 and repelled by the positive pressure of the second electrode 132. This prevents the cations from gathering at the second electrode 132, hindering the formation of an electron sheath and reducing the electron sheath's attraction to the cations. Furthermore, the cations are accelerated toward the first electrode 131, facilitating their movement toward the first electrode 131. This results in a stronger bombardment of the cations on the workpiece 200 and improves the etching effect on the workpiece 200.

[0081] For example, see Figure 1 An impedance matcher 156 may be electrically connected between the second RF bias source 152 and the second electrode 132. Impedance matcher 156 can improve feeding efficiency. Alternatively, a capacitor 157 may be electrically connected between the second RF bias source 152 and the second electrode 132. Capacitor 157 does not allow direct current to pass through, but allows alternating current to pass through. Alternatively, an impedance matcher 156 and capacitor 157 may be electrically connected between the second RF bias source 152 and the second electrode 132, with capacitor 157 located between the second electrode 132 and impedance matcher 156.

[0082] It is understood that a capacitor 157 and / or an impedance matcher 156 may be provided between at least one of the first electrode 131 and the RF excitation source 154, between the first electrode 131 and the first RF bias source 151, and between the second electrode 132 and the second RF bias source 152. The first RF bias source 151, the second RF bias source 152, and the RF excitation source 154 may be enabled simultaneously, or one or more of them may be enabled at will.

[0083] In some examples, the first RF bias source 151 and the second RF bias source 152 can be formed by two independent high frequency power generators. Figure 6 , the first RF bias source 151 and the second RF bias source 152 can be formed by the same RF bias source 153 through a power converter 155, and are electrically connected to the first electrode 131 and the second electrode 132 respectively. The power converter 155 can be used to distribute the RF power generated by the RF bias source 153 to the first electrode 131 and the second electrode 132. The power distribution of the first electrode 131 and the second electrode 132 can be synchronously adjusted by the power converter 155 to better control the movement of electrons. For example, the RF bias source 153 may include a high-frequency power generator. Among them, the input terminal A of the power converter 155 is connected to the RF bias source 153, the first output terminal B1 of the power converter 155 is electrically connected to the first electrode 131, and forms the first RF bias source 151, and the second output terminal B2 of the power converter 155 is electrically connected to the second electrode 132, and forms the second RF bias source 152. For example, an impedance matcher 156 may be provided between the RF bias source 153 and the power converter 155. The RF bias source 153 may transmit RF power through the impedance matcher 156. The impedance matcher 156 is used to match the impedance behind the RF bias source 153 to improve the feeding efficiency of the RF bias source 153. In an embodiment in which a capacitor 157 is provided between the first electrode 131 and the first RF bias source 151 and between the second electrode 132 and the second RF bias source 152, the capacitor 157 may be provided between the first output terminal B1 and the first electrode 131, and the capacitor 157 may be provided between the second output terminal B2 and the second electrode 132.

[0084] The radio frequency excitation source 154 provided in the embodiment of the present disclosure is described below.

[0085] It is understood that during the etching process, cations bombard the surface material of the workpiece 200, breaking chemical bonds between the material on the surface of the workpiece 200 and generating etching byproducts with the plasma. These etching byproducts are then separated from the surface of the workpiece 200, thereby completing the etching process. If the plasma continues to bombard the surface of the workpiece 200, the etching byproducts cannot be separated from the surface of the workpiece 200 in a timely manner (for example, the etching byproducts cannot be promptly discharged from the grooves formed by etching, resulting in the accumulation of etching byproducts in the grooves). This can lead to the accumulation of etching byproducts on the surface of the workpiece 200, thereby affecting subsequent etching processes, for example, affecting etching uniformity and / or failing to achieve a high aspect ratio.

[0086] In some embodiments, the RF excitation source 154 can be configured to provide pulsed power, that is, in an on-off-on-off operating mode. During the pulse-on period, the surface of the workpiece 200 is etched. During the pulse-off period, etching byproducts are ensured to be promptly separated from the surface of the workpiece 200, thereby reducing the accumulation of etching byproducts on the surface of the workpiece 200 and minimizing the impact on etching.

[0087] Figure 7 Figure 1 is a pulse waveform diagram of the RF excitation source 154. The pulse power supply can operate in an on / off mode, with the pulse on time being T1 and the pulse off time being T2. A pulse cycle is defined as T = T1 + T2. The duty cycle of the pulse power supply refers to the ratio of the pulse on time to the total pulse time within a pulse cycle (T1 / T). During the pulse on period, the workpiece 200 is etched, and during the pulse off period, etching byproducts are removed.

[0088] For example, the pulse power supply can alternately output at least two pulse signals, and at least two pulse signals have different duty cycles. By setting multiple pulse signals with different duty cycles, different etching morphologies can be formed. In addition, multiple pulse signals with different duty cycles can be set based on the molecular weight of etching byproducts to facilitate the discharge of etching byproducts of different molecular weights.

[0089] For example, see Figure 7, at least two pulse signals may include a first pulse signal M1 and a second pulse signal M2, and the duty cycle of the first pulse signal M1 is smaller than the duty cycle of the second pulse signal M2. The duty cycle of the first pulse signal M1 is small, and the pulse off time (T2) is long, which is conducive to the separation of etching byproducts from the surface of the workpiece 200 to be processed. The duty cycle of the second pulse signal M2 is large, and the etching duration (pulse on time T1) of the workpiece 200 to be processed is long, which can improve the efficiency of etching and is conducive to etching high aspect ratio morphology. The two RF working modes work in coordination, that is, the alternating first pulse signal M1 and the second pulse signal M2, which is conducive to increasing the control of the etching morphology, and can ensure the etching morphology with a high aspect ratio without affecting the separation of etching byproducts from the surface of the workpiece 200. For example, the capacitively coupled plasma processing device can be used to prepare dynamic random access memory (DRAM), which can be conducive to the preparation of high and small capacitors, thereby increasing the number of capacitors in the DRAM to increase the capacity of the DRAM.

[0090] The alternating arrangement of the first pulse signal M1 and the second pulse signal M2 may be such that at least one first pulse signal M1 alternates with at least one second pulse signal M2. For example, the alternating arrangement may be: m first pulse signals M1, n second pulse signals M2, m first pulse signals M1, n second pulse signals M2, and so on. n and / or m may vary over time or remain constant. n and m are positive integers greater than or equal to 1.

[0091] For example, the duty cycle of the first pulse signal M1 can be less than or equal to 1 / 2, which can ensure that the pulse off time of the first pulse signal M1 is longer, thereby facilitating the separation of etching byproducts from the surface of the workpiece 200. For example, this is beneficial for applications where the molecular weight of the etching byproducts is large or the etching depth is large. For example, the duty cycle of the first pulse signal M1 can be 1 / 5, 1 / 4, 1 / 3, 1 / 2, or any value less than 1 / 2.

[0092] For example, the duty cycle of the second pulse signal M2 can be greater than or equal to 3 / 4, which can ensure that the pulse on time of the second pulse signal M2 is longer, thereby improving etching efficiency and facilitating etching of high aspect ratio features. For example, the duty cycle of the second pulse signal M2 can be 3 / 4, 4 / 5, 5 / 6, or any value greater than 3 / 4.

[0093] For example, the power of the first pulse signal M1 can be less than the power of the second pulse signal M2. The lower power of the first pulse signal M1 results in a lower plasma density, thereby reducing the generation of etching byproducts and facilitating the separation of the etching byproducts generated by the first pulse signal M1 and the etching byproducts generated by the second pulse signal M2 from the surface of the workpiece 200. The higher power of the second pulse signal M2 results in a higher plasma density, thereby improving the etching efficiency of the workpiece 200 and facilitating the etching of high aspect ratio features.

[0094] In other examples, the frequencies of the first pulse signal M1 and the second pulse signal M2 can be different, thereby promptly removing etching byproducts, making the surface of the workpiece 200 cleaner, and reducing or preventing the deposition of etching byproducts on the surface of the workpiece 200, which would prevent the plasma from etching the film structure beneath the deposits, thereby reducing or preventing the impact on the subsequent etching process. In addition, the frequencies of the two pulse signals can be adjusted to adjust the etching uniformity, making the various feature sizes on the surface of the workpiece 200 more uniform.

[0095] It should be noted here that the numerical values ​​and numerical ranges involved in the embodiments of the present disclosure are approximate values. Due to the influence of the manufacturing process, there may be a certain range of errors. Those skilled in the art may consider this part of the error to be negligible.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A capacitively coupled plasma processing device, characterized in that: include: A housing, a first electrode, a second electrode, a first RF bias source, and a second RF bias source, wherein the housing has a receiving cavity, the first electrode and the second electrode are both located in the receiving cavity and are at least partially opposite to each other, and the workpiece is located on a side of the first electrode facing the second electrode; The first RF bias source is electrically connected to the first electrode, the second RF bias source is electrically connected to the second electrode, the frequencies of the first RF bias source and the second RF bias source are equal and are separated by half a cycle; It also includes a radio frequency excitation source, the radio frequency excitation source is electrically connected to the first electrode, and the frequency of the radio frequency excitation source is greater than the frequency of the first radio frequency bias source; Wherein, the RF excitation source is a pulse power supply, and the pulse power supply alternately outputs at least two pulse signals, and the at least two pulse signals include a first pulse signal and a second pulse signal, and the duty cycle of the first pulse signal is smaller than the duty cycle of the second pulse signal.

2. The capacitively coupled plasma processing apparatus according to claim 1, wherein: The invention comprises a power converter and a radio frequency bias source, wherein the input end of the power converter is connected to the radio frequency bias source, the first output end of the power converter is electrically connected to the first electrode to form the first radio frequency bias source, and the second output end of the power converter is electrically connected to the second electrode to form the second radio frequency bias source.

3. The capacitively coupled plasma processing apparatus according to claim 1, wherein: The power of the first pulse signal is less than the power of the second pulse signal.

4. The capacitively coupled plasma processing apparatus according to claim 1, wherein: The duty cycle of the first pulse signal is less than or equal to 1 / 2, and / or the duty cycle of the second pulse signal is greater than or equal to 3 / 4.

5. The capacitively coupled plasma processing apparatus according to claim 1, wherein: The first pulse signal and the second pulse signal have different frequencies.

6. The capacitively coupled plasma processing apparatus according to claim 1, wherein: The device further includes a capacitor, wherein the capacitor is provided at least one of between the first electrode and the RF excitation source, between the first electrode and the first RF bias source, and between the second electrode and the second RF bias source.

7. The capacitively coupled plasma processing apparatus according to claim 1, wherein: An impedance matcher is also included. The impedance matcher is provided at least one of between the first electrode and the RF excitation source, between the first electrode and the first RF bias source, and between the second electrode and the second RF bias source.

8. The capacitively coupled plasma processing apparatus according to claim 1 or 2, wherein: Also includes: A carrier, the carrier is located in the accommodating cavity and is located on a side of the first electrode facing the second electrode, the side of the carrier facing the second electrode having a carrying surface, and the workpiece to be processed is located on the carrying surface; A focusing ring, the focusing ring being arranged on the outer periphery of the carrying surface; The first electrode and the second electrode extend in the same direction; or, the second electrode includes a first extending portion and a second extending portion connected to each other, the first extending portion is arranged opposite to the first electrode and extends in the same direction, and the second extending portion is located at an edge of the first extending portion and extends toward the first electrode; The capacitively coupled plasma processing device includes a capacitively coupled plasma etching device.

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