Plasma etching method, plasma etching apparatus, control method, and computer-readable storage medium

Abstract

The application discloses a kind of plasma etching method, plasma etching equipment, control method and computer readable storage medium, it is related to the field of semiconductors, for solving the problem that wafer surface is subjected to particle pollution without interrupting plasma etching process sequence.The plasma etching method includes etching stage, transition stage and desorption stage;Etching stage includes: under first environmental parameter, etching is carried out to wafer placed in etching chamber;The first environmental parameter includes first power and first chamber pressure;Transition stage includes: the chamber pressure of the etching chamber is stepped up from the first chamber pressure to the second chamber pressure;Desorption stage includes: under second environmental parameter, desorption treatment is carried out to the wafer;The second environmental parameter includes second power and second chamber pressure, and the second power is less than the first power.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a plasma etching method, plasma etching equipment, control method, and computer-readable storage medium. Background Technology

[0002] In plasma etching processes, especially in capacitively coupled plasma (CCP) etching, particulate contaminants generated within the process chamber are a key factor leading to product defects and reduced yield. The bombardment of components within the chamber (such as the upper electrode, chamber walls, and electrostatic chuck) by high-energy plasma generates particulate contaminants that contaminate the wafer or deposit on the chamber surface via sputtering; simultaneously, reaction byproducts also deposit on the chamber surface. During the process, these particles and reaction byproducts may peel off and resuspend due to plasma disturbances, pressure surges, or thermal stress, ultimately depositing on the wafer surface and forming defects.

[0003] Currently, the commonly used particle control strategies mainly rely on wet or dry cleaning that involves periodically interrupting equipment operation. This passive maintenance method significantly reduces equipment utilization, affects the continuous production capacity of the production line, and cannot suppress particle contamination during process equipment operation in real time. In addition, related technologies also mitigate particle generation by replacing hardware materials such as chamber linings with more splash-resistant ones, but this approach incurs additional costs and fails to fundamentally solve the problem of dynamic particle generation and adhesion in the process flow.

[0004] Therefore, there is an urgent need for a solution that can achieve real-time control of particulate contamination in the etching process without interrupting the normal process flow. Summary of the Invention

[0005] This application discloses a plasma etching method, plasma etching equipment, control method, and computer-readable storage medium, which are used to solve the problem of reducing particle contamination on the wafer surface without interrupting the plasma etching process sequence.

[0006] In a first aspect, this application provides a plasma etching method, including an etching stage, a transition stage, and a desorption stage; the etching stage includes: etching a wafer placed in an etching chamber under first environmental parameters; the first environmental parameters include a first power and a first chamber pressure; the transition stage includes: increasing the chamber pressure of the etching chamber from the first chamber pressure to a second chamber pressure in a stepwise manner; the desorption stage includes: performing a desorption treatment on the wafer under second environmental parameters; the second environmental parameters include a second power and a second chamber pressure, wherein the second power is less than the first power.

[0007] In the embodiments of this application, a transition stage is added between the etching stage and the desorption stage. This allows for the control of particulate contamination in the plasma etching process without interrupting normal equipment operation and the corresponding process flow. The transition stage employs a stepped transition process, which enables a smooth switching of power and pressure, preventing large-scale peeling off of loosened particles due to inertial forces caused by a sudden drop in ion bombardment energy during the process flow. Simultaneously, the chamber pressure of the etching chamber is increased stepwise from the first chamber pressure to the second chamber pressure during the transition stage, avoiding strong airflow disturbances caused by sudden pressure changes. These airflow disturbances prevent accidental peeling off and resuspension of particles attached to the chamber walls and component surfaces, reducing the risk of particulate contamination on the wafer surface during the process flow.

[0008] In one possible implementation, the step of increasing the chamber pressure of the etching chamber from the first chamber pressure to the second chamber pressure in a stepped manner includes a first sub-stage and a second sub-stage; the first sub-stage includes: increasing the chamber pressure of the etching chamber from the first chamber pressure to the third chamber pressure, wherein the chamber pressure of the etching chamber is maintained at the third chamber pressure for a first preset time; the second sub-stage includes: increasing the chamber pressure of the etching chamber from the third chamber pressure to the second chamber pressure.

[0009] The aforementioned first preset time is the time required for the plasma equipment to reach a stable operating state. This state may include at least one of the following: chamber pressure, gas flow rate, and temperature. By maintaining this first preset time, a smooth transition in chamber pressure and gas flow rate can be achieved. This ensures that during the transition phase, the gas carrying particulate matter can flow stably towards the vacuum pump in a defined direction. This keeps the opening of the throttle valve stable, preventing turbulence caused by the flow rate increase, reducing disturbance to the particulate matter within the etching chamber, and ensuring that the particulate matter is extracted along a defined direction, thus avoiding wafer contamination. Furthermore, the throttle valve opening will not suddenly increase, preventing impact or vibration to the vacuum pump caused by drastic fluctuations in gas pressure or flow rate, extending its lifespan. Temperature stability reduces differences in etching rates and improves etching uniformity.

[0010] In one possible implementation, the transition phase further includes: reducing the power of the etching chamber from the first power to the second power in a stepped manner.

[0011] By using a stepped power reduction method, a smooth transition of ion energy can be ensured, avoiding the "charge effect" caused by charge accumulation on the wafer surface. At the same time, it compensates for the change in ionization rate caused by increased pressure, preventing large-scale sputtering of loosened particles due to inertial forces caused by a sudden drop in ion bombardment energy.

[0012] In one possible implementation, the step of reducing the power of the etching chamber from the first power to the second power in a stepped manner includes: a first sub-stage including: reducing the power of the etching chamber from the first power to the third power, wherein the power of the etching chamber is maintained at the third power for a second preset time; and a second sub-stage including: reducing the power of the etching chamber from the third power to the second power.

[0013] By gradually decreasing the power, accumulated charges can be slowly and uniformly neutralized or released through the plasma sheath, avoiding electrostatic damage caused by excessive potential difference. The second preset time is the time it takes for the plasma equipment to reach a stable operating state, which includes at least the plasma's reflected power. In other words, during the second preset time, the plasma excitation efficiency and ion energy can be finely adjusted to achieve a phased and smooth transition of power and pressure. This ensures a gradual transition of ion energy during the transition phase, avoiding the "charge effect" caused by charge accumulation on the wafer surface. At the same time, it compensates for the change in ionization rate caused by the increase in pressure, preventing large-scale sputtering of loosened particles due to inertial forces caused by a sudden drop in ion bombardment energy.

[0014] In one possible implementation, the ratio of the third power to the sum of the first power and the second power is in the range of 0.4 to 0.6; and / or, the ratio of the third chamber pressure to the sum of the first chamber pressure and the second chamber pressure is in the range of 0.4 to 0.6.

[0015] Setting the above ratio range can maintain the relative stability of the throttle valve opening, avoid turbulence or pressure overshoot in the etching chamber, reduce disturbance to particulate matter in the etching chamber, ensure that particulate matter can be drawn away in a certain direction, and avoid contaminating the wafer; while controlling the plasma reflection ratio is to control the impedance matching degree between the plasma etching chamber and the RF power supply, thereby ensuring the stability of the etching chamber environment and the stability of the plasma.

[0016] In one possible implementation, the first environmental parameter further includes: a first flow rate, which is the flow rate of the etching gas introduced into the etching chamber during the etching stage; the first sub-stage further includes: maintaining the flow rate of the etching gas at the first flow rate; the second sub-stage further includes: reducing the flow rate of the etching gas from the first flow rate to a second flow rate, and introducing a desorption gas at a third flow rate.

[0017] By maintaining the etching gas flow rate at a constant level in the first sub-stage, the inertia of the airflow is preserved, ensuring that particulate matter continues its directional movement along a predetermined path and does not drift erratically due to fluctuations in chamber pressure. In the second sub-stage, the decrease in flow rate is synchronized with the increase in chamber pressure, ensuring a new equilibrium between the convection and diffusion velocities of gas molecules within the etching chamber, thus avoiding localized eddies caused by sudden changes in flow rate. Furthermore, as the first flow rate decreases to the second flow rate, a third flow rate is introduced to ensure a smooth change in the total number of gas molecules, maintaining a stable gas flow field and preventing particle resuspension and secondary adhesion caused by valve overshoot or sudden changes in airflow, thereby reducing the risk of particle adsorption on the wafer surface.

[0018] In one possible implementation, the ratio of the second flow rate to the first flow rate is in the range of 0.4 to 0.6.

[0019] Setting the above ratio range ensures that the reduction in flow rate matches the change in pumping speed of the molecular pump caused by the increase in chamber pressure, thereby ensuring the relative stability of the throttle valve opening, the stability of the environment in the etching chamber 10, and thus avoiding turbulence or chamber pressure overshoot in the etching chamber 10. This reduces disturbance to particulate matter in the etching chamber 10, ensuring that particulate matter can be pumped away in a defined direction, and preventing wafer contamination.

[0020] In one possible implementation, the third flow rate is greater than the second flow rate.

[0021] By setting the flow rate, a stable gas flow field can be maintained during gas exchange, avoiding local airflow rebound and eddies. This also prevents particle resuspension and secondary adhesion caused by overshooting of the throttle valve or sudden changes in airflow, reducing the risk of particle adsorption on the wafer surface.

[0022] In one possible implementation, the transition phase further includes a third sub-phase: reducing the flow rate of the etching gas to 0 and continuing to introduce the desorbed gas into the etching chamber at a fourth flow rate; wherein the fourth flow rate is greater than the third flow rate.

[0023] By introducing a fourth flow rate of desorption gas while the etching gas flow rate decreases, an equal displacement of etching gas to desorption gas can be achieved, maintaining a stable pressure field and keeping the throttle valve opening stable. This avoids particle resuspension and secondary adhesion caused by pressure fluctuations, reducing the risk of particle adsorption on the wafer surface. Setting the fourth flow rate to be greater than the third flow rate, and having a higher dynamic pressure, the fourth flow rate can remove residual gas from areas that are difficult to reach by diffusion alone, thus purifying the etching chamber.

[0024] In one possible implementation, the second environmental parameter further includes a fifth flow rate, which is the flow rate of the desorbed gas introduced into the etching chamber during the desorption stage; the fifth flow rate is greater than the fourth flow rate.

[0025] By setting the flow rate of the desorbed gas to increase in a stepwise manner, the stability of the throttle valve opening is ensured, a stable gas flow field is maintained, and particle resuspension and secondary adhesion caused by overshooting of the throttle valve adjustment or sudden changes in airflow are avoided, thereby reducing the risk of particle adsorption on the wafer surface.

[0026] In one possible implementation, the sum of the third flow rate and the fourth flow rate is equal to the fifth flow rate.

[0027] The above flow rate relationship ensures that the flow rate of desorption gas introduced into the etching chamber is continuous from the second sub-stage to the third sub-stage and then to the desorption stage, so as to avoid residual etching gas being left behind. Through the phenomenon of diffusion backflow, the gas environment in the etching chamber is made to have a sufficient flow of desorption gas.

[0028] In one possible implementation, the product of the fifth flow rate and the relative atomic mass of the desorbed gas is greater than the product of the first flow rate and the relative atomic mass of the etching gas.

[0029] By setting the above parameter relationships, it can be ensured that when the particulate matter in the etching chamber is falling from the wall, the airflow in the desorption stage can exert a greater upward drag force. This force is sufficient to counteract the gravity of the particulate matter, preventing it from falling and settling onto the wafer surface, but instead lifting it until it flows to the molecular pump.

[0030] In one possible implementation, the fifth flow rate ranges from 200 sccm to 800 sccm.

[0031] The setting of the fifth flow rate range mentioned above can apply sufficient drag force to the residual particulate matter after etching, preventing it from falling and settling on the wafer surface. The particulate matter is in a supported state until it flows stably towards the molecular pump in a certain direction, and will not be resuspended or re-attached due to turbulence.

[0032] In one possible implementation, an radio frequency (RF) signal is applied to the RF electrodes of the etching chamber, the RF signal being a periodic pulse signal; the first power, the second power, and the third power are the power during the high-level phase of the RF signal; during the etching phase and / or the transition phase, the power during the low-level phase of the RF signal is greater than 0.

[0033] By setting the power of the low-level phase of the radio frequency signal to be greater than 0, it is equivalent to maintaining a low-density plasma with low-level power. The plasma sheath still exists, meaning that the plasma sheath will not collapse. It can exert a repulsive force on negatively charged particulate matter during the etching and / or transition phases to prevent particulate matter from settling onto the wafer surface by gravity or airflow disturbance.

[0034] In one possible implementation, during the etching stage, the first sub-stage, and the second sub-stage, the power range of the low-level stage of the radio frequency signal is 100W to 600W.

[0035] The power range setting of the aforementioned low-level stage can provide sufficient electric field strength to ensure that the plasma sheath does not collapse and maintain a stable plasma sheath structure. It can apply a repulsive force to negatively charged particulate matter during the etching stage, the first sub-stage, and the second sub-stage to prevent particulate matter from settling onto the wafer surface by gravity or airflow disturbance.

[0036] In one possible implementation, the radio frequency signal is a bias radio frequency signal, the first power ranges from 5000W to 33000W, the second power ranges from 100W to 600W, and the third power ranges from 100W to 15000W.

[0037] In one possible implementation, the radio frequency signal is a source radio frequency signal, the first power ranges from 1000W to 15000W, the second power ranges from 100W to 600W, and the third power ranges from 500W to 8000W.

[0038] By gradually decreasing the power, the accumulated charge can be slowly and uniformly neutralized or released through the plasma sheath, avoiding electrostatic damage caused by excessive potential difference.

[0039] In one possible implementation, the pressure range of the first chamber is 10mT to 30mT, the pressure range of the second chamber is 100mT to 500mT, and the pressure range of the third chamber is 50mT to 250mT.

[0040] By gradually increasing the chamber pressure, strong airflow disturbances caused by sudden pressure changes are avoided. These airflow disturbances prevent accidental peeling and resuspension of particles attached to the chamber walls and component surfaces, reducing the risk of wafer surface particle contamination during the process.

[0041] Secondly, this application provides a plasma etching apparatus, including an etching chamber, a gas delivery system, a pressure control system, a radio frequency electrode, and a first controller: the etching chamber is configured to accommodate a wafer; the gas delivery system is configured to deliver etching gas and / or desorption gas into the etching chamber; the pressure control system is configured to control the chamber pressure within the etching chamber; the radio frequency electrode is configured to receive a radio frequency signal and, based on the radio frequency signal, apply radio frequency power to the etching chamber; the first controller is configured to control the gas delivery system, the pressure control system, and the radio frequency electrode to perform the method described in any of the above embodiments. Therefore, the first controller provided by this application has all the beneficial effects of the plasma etching method provided in any of the above embodiments, which will not be elaborated here.

[0042] Thirdly, this application provides a control method for a plasma etching apparatus, the plasma etching apparatus including an etching chamber, a gas delivery system, a pressure control system, and a radio frequency motor; the method includes: in an etching stage, controlling the pressure control system to adjust the chamber pressure in the etching chamber to a first chamber pressure, and controlling the radio frequency electrode to apply a first power to the etching chamber to etch a wafer placed in the etching chamber; in a transition stage, controlling the pressure control system to increase the chamber pressure in the etching chamber from the first chamber pressure to a second chamber pressure in a stepped manner; in a desorption stage, controlling the pressure control system to adjust the chamber pressure in the etching chamber to the second chamber pressure, and controlling the radio frequency electrode to apply a second power to the etching chamber to desorb the wafer placed in the etching chamber; wherein the second power is less than the first power.

[0043] By precisely coordinating and controlling each subsystem, the stability of the plasma etching equipment is ensured, and the uniformity of the etching rate is guaranteed. At the same time, the stepped increase in chamber pressure avoids strong airflow disturbances caused by sudden pressure changes. Airflow disturbances prevent accidental peeling and resuspension of particles attached to the chamber walls and component surfaces, reducing the risk of particle contamination on the wafer surface during the process. Furthermore, it ensures that the particles always move stably in a defined direction without backflow or stagnation, guaranteeing the "self-cleaning" capability of the etching chamber.

[0044] In one possible implementation, the method further includes: during the transition phase, controlling the power of the etching chamber to decrease in a stepwise manner from the first power to the second power.

[0045] By controlling the stepwise decrease in power, a smooth transition of ion energy can be ensured, avoiding the "charge effect" caused by charge accumulation on the wafer surface. At the same time, it compensates for the change in ionization rate caused by the increase in pressure, and avoids the large-scale sputtering of loose particles due to inertial force caused by the sudden drop in ion bombardment energy.

[0046] Fourthly, this application provides a computer-readable storage medium storing instructions that, when executed on a computer, enable the computer to perform the control method described in the above embodiments.

[0047] Fifthly, this application provides a computer program product, including computer program code or instructions, which, when executed on a computer, cause the control method described in the above embodiments to be performed.

[0048] Sixthly, this application also provides a plasma etching method, including an etching stage and a desorption stage; the etching stage includes: etching a wafer placed in the etching chamber by sending a radio frequency (RF) signal to an RF electrode in the etching chamber; the RF signal has a first power; the desorption stage includes: reducing the power of the RF signal from the first power to a second power to desorb the wafer; wherein the RF signal is a periodic pulse signal, the first power and the second power are the power of the high-level phase of the RF signal, and in the etching stage, the power of the low-level phase of the RF signal is greater than 0.

[0049] By setting the power of the low-level stage of the radio frequency signal to be greater than 0 during the etching stage, it is equivalent to maintaining a low-density plasma with low-level power, ensuring the existence of the plasma sheath, that is, the plasma sheath will not collapse. This allows the negatively charged particulate matter to be repelled during the etching stage, so as to prevent the particulate matter from settling to the wafer surface by gravity or airflow disturbance.

[0050] In one possible implementation, during the etching stage, the chamber pressure of the etching chamber is a first chamber pressure; between the etching stage and the desorption stage, the plasma etching method further includes a transition stage, comprising: increasing the chamber pressure of the etching chamber from the first chamber pressure to a second chamber pressure in a stepped manner, and reducing the power of the high-level stage of the radio frequency signal from the first power to the second power; wherein, during the transition stage, the power of the low-level stage of the radio frequency signal is greater than 0.

[0051] During the control transition phase, the chamber pressure increases in a stepwise manner, avoiding strong airflow disturbances caused by sudden pressure changes. These airflow disturbances prevent accidental peeling and resuspension of particles attached to the chamber walls and component surfaces, reducing the risk of wafer surface particle contamination during the process. Simultaneously, during the control transition phase, the power of the low-level RF signal is greater than zero, enhancing the efficiency of particle count control and further reducing the risk of wafer surface particle contamination.

[0052] In one possible implementation, during the etching stage and / or the transition stage, the power range of the low-level phase of the radio frequency signal is 100W to 600W.

[0053] By setting the power range of the low-level phase of the RF signal during the etching and / or transition phases, sufficient electric field strength can be provided to ensure that the plasma sheath does not collapse during the etching and / or transition phases, maintaining a stable plasma sheath structure. This allows the plasma sheath to exert a repulsive force on negatively charged particulate matter, preventing it from settling onto the wafer surface by gravity or airflow disturbance.

[0054] In a seventh aspect, this application provides a plasma etching apparatus, including a unit / module for performing the plasma etching method as described in the sixth aspect. Attached Figure Description

[0055] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0056] Figure 1 This is a structural diagram of the plasma etching apparatus according to an embodiment of this application; Figure 2 This is a structural diagram of the etching chamber according to an embodiment of this application; Figure 3 This is a flowchart of a plasma etching method according to an embodiment of this application; Figure 4 This is another flowchart of the plasma etching method according to an embodiment of this application; Figure 5 This is a particle defect image after a plasma etching process, as shown in some embodiments of related technologies. Figure 6 This is another particle defect image after plasma etching process in some embodiments of related technologies; Figure 7A This is a particle defect diagram after plasma etching process according to an embodiment of this application; Figure 7B This is another particle defect diagram after the plasma etching process in an embodiment of this application; Figure 8A This is another particle defect diagram after the plasma etching process in an embodiment of this application. Figure 8B This is another particle defect image after the plasma etching process in this application embodiment; Figure 9 This is a line graph comparing the particle number as a function of radio frequency time in embodiments of this application and related technologies.

[0057] Explanation of reference numerals in the attached figures: 100 - Plasma etching equipment; 10 - Etching chamber; 1-Electrostatic chuck; 11-Base; 12-Insulator; 13-Lower electrode; 2-Upper electrode; 3-Plasma sheath; 20 - Gas delivery system; 30 - Air pressure control system; 40 - Radio frequency electrode; 50 - First Controller; S1 - Etching stage; S2 - Transition phase; S21 - First sub-phase; S22 - Second sub-phase; S23 - Third sub-phase; S3 - Desorption stage; F1 - Pressure in the first chamber; F2 - Pressure in the second chamber; F3 - Pressure in the third chamber; P1 - First power; P2 - Second power; P3 - Third power; L1 - First flow; L2 - Second flow; L3 - Third flow; L4 - Fourth flow; L5 - Fifth flow. Detailed Implementation

[0058] like Figure 1 As shown, this application provides a plasma etching apparatus 100, which is mainly used in the manufacturing of semiconductor devices. As a very important component, the plasma etching apparatus 100 mainly functions to achieve nanometer-level precision control and pattern transfer, as well as control of particulate contamination and process continuity.

[0059] It should be noted that the plasma etching equipment 100 uses a "dry" etching method, which is different from wet etching using chemical solutions. It utilizes plasma, a "gas" composed of high-energy substances such as charged particles and free radicals, to achieve precise processing, reduce wafer damage, and improve etching efficiency.

[0060] In some embodiments, such as Figure 1 As shown, Figure 1 This is a structural diagram of a plasma etching apparatus 100, which includes an etching chamber 10, a gas delivery system 20, a pressure control system 30, a radio frequency electrode 40, and a first controller 50. The etching chamber 10 is configured to accommodate a wafer; the gas delivery system 20 is configured to deliver etching gas and / or desorption gas into the etching chamber 10; the pressure control system 30 is configured to control the chamber pressure within the etching chamber 10; the radio frequency electrode 40 is configured to receive radio frequency signals and, based on the radio frequency signals, apply radio frequency power to the etching chamber 10; and the first controller 50 is configured to control the gas delivery system 20, the pressure control system 30, and the radio frequency electrode 40.

[0061] For example, the etching chamber 10 is a closed reaction space that can hold the wafer and isolate it from the external environment.

[0062] For example, the gas delivery system 20 precisely adjusts the gas ratio and flow rate through a mass flow controller, ensuring etching rate and uniformity. The etching gas can be a fluorocarbon gas used for chemical etching, such as carbon tetrafluoride (CF4), tetracarbon octafluoride (C4F8), dicarbide hexafluoride (C2F6), oxygen, etc., and the desorption gas is used to remove reaction byproducts, including argon (Ar).

[0063] For example, the air pressure control system 30 controls the chamber pressure in the etching chamber 10 to maintain it within a reasonable range, so as to avoid the chamber pressure being too high, which would reduce the plasma density and affect the etching rate, or the chamber pressure being too low, which might cause arc discharge and damage the electrode.

[0064] The pressure control system 30 may include a vacuum pump and a throttle valve, wherein the vacuum pump may be a molecular pump. During the etching process, the vacuum pump and the throttle valve work together, and the pressure control system 30 controls and adjusts the pumping speed or air intake of the vacuum pump to ensure the stability of the chamber pressure within the etching chamber 10.

[0065] For example, the radio frequency electrode 40 receives a radio frequency signal and, based on the radio frequency signal, applies radio frequency power to the etching chamber 10, causing the gas to ionize and form plasma under the action of an electric field.

[0066] For example, the first controller 50 collects data in real time through sensors (such as pressure sensors or flow meters) and then adjusts parameters to achieve precise control. These parameters include gas ratio, chamber pressure, power, etc. For instance, when a pressure fluctuation is detected, the first controller 50 adjusts the vacuum pump speed to maintain stability.

[0067] It should be noted that the above-described plasma etching apparatus 100 including the first controller 50 is merely an example. Specifically, the first controller 50 can be located inside or outside the plasma etching apparatus 100, or a portion of the first controller 50 may be located inside the plasma etching apparatus 100, while another portion may be located outside. The etching chamber 10 is used to receive commands sent by the first controller 50.

[0068] In the embodiments of this application, the etching methods of the plasma etching apparatus 100 include, but are not limited to, capacitively coupled plasma etching. The following description uses capacitively coupled plasma etching as an example.

[0069] In some embodiments, refer to Figure 2 The etching chamber 10 includes an electrostatic chuck 1, which includes a base 11 and an insulator 12 disposed on the base 11. A lower electrode 13 is disposed inside the insulator 12, and an upper electrode 2 is disposed above the base 11.

[0070] For example, the electrostatic chuck 1 uses the principle of electrostatic adsorption to firmly adsorb the wafer onto its surface, which can avoid physical contact, prevent the wafer surface from being scratched or contaminated, and ensure the absolute stability of the wafer under high-speed rotation or plasma impact, providing a basic guarantee for high-precision etching.

[0071] For example, such as Figure 2 As shown, the base 11 is made of a high thermal conductivity material and integrates a coolant channel and a temperature sensor, which can achieve precise temperature control on the back side of the wafer to avoid wafer warping or doping diffusion caused by thermal stress.

[0072] For example, the material of insulator 12 is aluminum nitride (AlN) or aluminum oxide (Al2O3).

[0073] For example, such as Figure 1 As shown, and in combination Figure 2 The radio frequency electrode 40 is disposed inside the etching chamber 10. The radio frequency electrode 40 includes an upper electrode 2 and a lower electrode 13. The upper electrode 2 and the lower electrode 13 form a parallel plate capacitor structure. When a radio frequency signal is applied, an electric field is excited, and the gas is ionized to generate plasma.

[0074] It should be noted that in plasma etching processes, particulate contaminants generated by plasma bombardment or reaction byproducts can peel off and deposit on the wafer surface, leading to wafer defects and reduced yield. If periodic cleaning or replacement of sputtering materials is used, it requires interrupting normal equipment operation, resulting in low equipment utilization, high costs, and the inability to suppress dynamic contamination in real time.

[0075] Based on this, the plasma etching method provided in this application can achieve real-time control of particulate contamination in the etching process without interrupting the normal process flow.

[0076] like Figure 3 As shown, Figure 3 This is a flowchart of a plasma etching method according to an embodiment of this application. The plasma etching method provided in this application is applied in a plasma etching apparatus 100. The plasma etching method includes an etching stage S1, a transition stage S2, and a desorption stage S3.

[0077] The etching stage S1 includes: etching a wafer placed in an etching chamber under first environmental parameters; the first environmental parameters include a first power and a first chamber pressure; The transition phase S2 includes: increasing the chamber pressure of the etching chamber 10 from the first chamber pressure F1 to the second chamber pressure F2 in a stepwise manner; The desorption stage S3 includes: performing desorption treatment on the wafer under the second environmental parameters; the second environmental parameters include the second power P2 and the second chamber pressure F2, wherein the second power P2 is less than the first power P1.

[0078] In the embodiments of this application, by adding a transition stage S2 between the etching stage S1 and the desorption stage S3, and by adopting a step-like transition process in the transition stage S2, a smooth switching of power and pressure can be achieved, avoiding the large-scale peeling off of loosened particles under the action of inertial force due to the sudden drop in ion bombardment energy during the process. At the same time, in the transition stage S2, the chamber pressure of the etching chamber 10 is increased stepwise from the first chamber pressure F1 to the second chamber pressure F2, avoiding strong airflow disturbances caused by sudden pressure changes. Airflow disturbances prevent accidental peeling off and resuspension of particles attached to the chamber wall and component surface, reducing the risk of wafer surface particle contamination during the process.

[0079] It should be noted that the chamber pressure of the etching chamber 10 increases in a stepwise manner from the first chamber pressure F1 to the second chamber pressure F2. This stepwise increase means that the chamber pressure of the etching chamber 10 is not continuous from the first chamber pressure F1, but gradually increases to the second chamber pressure F2 in stages. Each stage corresponds to a specific chamber pressure range. By precisely controlling the gas flow rate, the pumping speed of the vacuum pump, and the plasma parameters, the yield of the etching process can be improved.

[0080] For example, the chamber pressure of the etching chamber 10 increases in a stepwise manner from the first chamber pressure F1 to the second chamber pressure F2. This can be achieved by first increasing the first chamber pressure F1 to a preset chamber pressure, maintaining it for a preset time, and then continuing to increase until it reaches the second chamber pressure F2. Here, the preset chamber pressure can be at least one between the first chamber pressure F1 and the second chamber pressure F2. For example, the preset chamber pressure includes both a first preset chamber pressure and a second preset chamber pressure. The preset time for maintaining the first preset chamber pressure and the preset time for maintaining the second preset chamber pressure can be the same or different, depending on the gas state and the requirements for particulate matter control, etc.

[0081] In some implementations, such as Figure 4 As shown, combined with Figure 3 The etching chamber 10 is raised from the first chamber pressure F1 to the second chamber pressure F2 in a stepwise manner, including a first sub-stage S21 and a second sub-stage S22. The first sub-stage S21 includes raising the chamber pressure of the etching chamber 10 from the first chamber pressure F1 to the third chamber pressure F3, wherein the chamber pressure of the etching chamber 10 is maintained at the third chamber pressure F3 for a first preset time. The second sub-stage S22 includes raising the chamber pressure of the etching chamber 10 from the third chamber pressure F3 to the second chamber pressure F2.

[0082] For example, the pressure F1 in the first chamber can range from 10 mT to 30 mT, the pressure F2 in the second chamber can range from 100 mT to 500 mT, the pressure F3 in the third chamber can range from 50 mT to 250 mT, and the first preset time can range from 3 s to 8 s. For instance, the pressure F1 in the first chamber is 30 mT, the pressure F3 in the third chamber is 70 mT, the pressure F2 in the second chamber is 100 mT, and the first preset time can range from 3 s to 8 s.

[0083] It should be noted that the first preset time is the time it takes for the plasma device 100 to reach a stable operating state. For example, the parameters used to represent the device state include at least one of chamber pressure, gas flow rate, and temperature. In other words, during the first preset time when the third chamber pressure F3 is maintained, a smooth transition in gas flow rate and from the first chamber pressure F1 to the third chamber pressure F3 can be achieved. This ensures that the gas carrying particulate matter in the transition phase S2 can flow stably towards the vacuum pump in a defined direction, keeping the opening of the throttle valve stable. This prevents the increase in flow rate from causing turbulence, reduces disturbance to the particulate matter in the etching chamber 10, and ensures that the particulate matter can be drawn away in a defined direction, avoiding wafer contamination. Furthermore, keeping the opening of the throttle valve from suddenly increasing prevents shocks or vibrations to the vacuum pump caused by drastic fluctuations in gas pressure or flow rate, extending its lifespan. Temperature stability reduces the difference in etching rates and improves etching uniformity.

[0084] In some implementations, such as Figure 3 As shown, the transition stage S2 also includes: reducing the power of the etching chamber 10 from the first power P1 to the second power P2 in a stepwise manner.

[0085] It should be noted that by using a stepped power reduction method, the ion energy transition is ensured to be smooth, avoiding the "charge effect" caused by charge accumulation on the wafer surface. At the same time, it compensates for the change in ionization rate caused by the increase in pressure, and avoids the large-scale sputtering of loose particles due to inertial force caused by the sudden drop in ion bombardment energy.

[0086] In some implementations, such as Figure 4 As shown, combined with Figure 3 The power of the etching chamber 10 is reduced from the first power P1 to the second power P2 in a stepped manner, including a first sub-stage S21 and a second sub-stage S22; wherein, the first sub-stage S21 includes: reducing the power of the etching chamber 10 from the first power P1 to the third power P3, wherein the power of the etching chamber 10 is maintained at the third power P3 for a second preset time; the second sub-stage S22 includes: reducing the power of the etching chamber 10 from the third power P3 to the second power P2.

[0087] It should be noted that an RF signal is applied to the RF electrode 40 of the etching chamber 10. The RF signal is a periodic pulse signal. The first power P1, the second power P2 and the third power P3 are the powers during the high-level phase of the RF signal.

[0088] For example, the power of the etching chamber 10 decreases in a stepped manner from a first power P1 to a second power P2. This can be achieved by first reducing the first power P1 to a preset power, such as a third power P3, maintaining this power for a second preset time, and then continuing to decrease until it reaches the second power P2. The preset power can be at least one preset power between the first power P1 and the second power P2. For example, the preset power includes a first preset power and a second preset power. The preset time for maintaining the first preset power and the preset time for maintaining the second preset power can be the same or different.

[0089] For example, when the radio frequency signal is a bias radio frequency signal, the range of the first power P1 is 5000W to 33000W, the range of the second power P2 is 100W to 600W, and the range of the third power P3 is 1000W to 15000W. For example, the first power P1 is 15500W, the third power P3 is 9000W, and the second power P2 is 200W. This is just an example; specifically, the settings of the first power P1, the second power P2, and the third power P3 refer to the above ranges.

[0090] For example, when the source radio frequency signal is the radio frequency signal, the range of the first power P1 is 1000W to 15000W, the range of the second power P2 is 100W to 600W, and the range of the third power P3 is 500W to 8000W. For example, the first power P1 is 10000W, the third power P3 is 5000W, and the second power P2 is 200W. This is just an example; specifically, the settings of the first power P1, the second power P2, and the third power P3 refer to the above ranges.

[0091] It should be noted that, as Figure 2 As shown, during the plasma etching process, the wafer is adsorbed onto the electrostatic chuck 1, and plasma is generated between the upper electrode 2 and the wafer. The bottom of the plasma near the wafer is the plasma sheath layer 3.

[0092] By gradually decreasing the power, the accumulated charge can be slowly and uniformly neutralized or released through the plasma sheath 3, avoiding electrostatic damage caused by excessive potential difference.

[0093] It should be noted that the second preset time is the time it takes for the plasma device 100 to reach a stable operating state. The parameters used to represent the device state include at least the plasma's reflected power. In other words, during the second preset time, the excitation efficiency and ion energy of the plasma can be finely adjusted, achieving a smooth transition in reflected power and chamber pressure. This ensures a gradual transition in ion energy during the S2 transition phase, avoiding the "charge effect" caused by charge accumulation on the wafer surface. Simultaneously, it compensates for the change in ionization rate caused by increased pressure, preventing large-scale sputtering of loosened particles due to inertial forces caused by a sudden drop in ion bombardment energy. The plasma excitation power can be used to control the plasma density; increasing the excitation power reduces the plasma's reflected power. The plasma's ion energy refers to the energy of the plasma bombarding the wafer, which can be adjusted by the radio frequency bias power supply. Impedance mismatch in the plasma load will cause an increase in reflected power.

[0094] In some implementations, the ratio of the third power P3 to the sum of the first power P1 and the second power P2 ranges from 0.4 to 0.6.

[0095] In other embodiments, the ratio of the third chamber pressure F3 to the sum of the first chamber pressure F1 and the second chamber pressure F2 ranges from 0.4 to 0.6.

[0096] For example, the above ratio range is set based on the throttle valve opening and the plasma reflection ratio (the ratio of the power reflected back to the RF power supply from the plasma load to the forward output power).

[0097] Specifically, maintaining a relatively stable opening of the throttle valve can prevent turbulence or pressure overshoot in the etching chamber 10, reduce disturbance to particulate matter within the etching chamber 10, and ensure that particulate matter is drawn away in a defined direction, thus preventing wafer contamination. Controlling the plasma reflection ratio is to control the impedance matching between the plasma in the etching chamber 10 and the RF power supply, thereby ensuring a stable environment in the etching chamber 10 and plasma stability. For example, the ratio of the third power P3 to the sum of the first power P1 and the second power P2 can be 0.4, 0.5, or 0.6, and the ratio of the third chamber pressure F3 to the sum of the first chamber pressure F1 and the second chamber pressure F2 can be 0.4, 0.5, or 0.6.

[0098] In some implementations, such as Figure 4 As shown, combined with Figure 3The first environmental parameter also includes: a first flow rate L1, which is the flow rate of the etching gas introduced into the etching chamber 10 during the etching stage S1; the first sub-stage S21 also includes: maintaining the flow rate of the etching gas at the first flow rate L1; the second sub-stage S22 also includes: reducing the flow rate of the etching gas from the first flow rate L1 to the second flow rate L2, and introducing the desorption gas at the third flow rate L3.

[0099] It should be noted that, as described above, in the first sub-stage S21, the chamber pressure of the etching chamber 10 is increased from the first chamber pressure F1 to the third chamber pressure F3. Furthermore, in the first sub-stage S21, the flow rate of the etching gas is kept constant at the first flow rate L1. This maintains the inertia of the airflow and ensures that the particulate matter can still move along the predetermined path and will not deviate from the path due to fluctuations in the chamber pressure.

[0100] In the second sub-stage S22, the chamber pressure of the etching chamber 10 is increased from the third chamber pressure F3 to the second chamber pressure F2. Simultaneously, the flow rate of the etching gas is reduced from the first flow rate L1 to the second flow rate L2, and a desorption gas is introduced at a third flow rate L3. This simultaneous decrease in flow rate and increase in chamber pressure ensures a new equilibrium between the convection and diffusion velocities of gas molecules within the etching chamber 10, preventing localized eddies caused by sudden flow rate changes. Furthermore, the simultaneous introduction of desorption gas at the third flow rate L3 while the first flow rate L1 decreases to the second flow rate L2 ensures a gradual change in the total number of gas molecules, maintaining a stable gas flow field and preventing particle resuspension and secondary adhesion due to valve overshoot or sudden airflow changes, thus reducing the risk of particle adsorption on the wafer surface.

[0101] In some implementations, the ratio of the second flow rate L2 to the first flow rate L1 ranges from 0.4 to 0.6.

[0102] For example, the ratio of the second flow rate L2 to the first flow rate L1 can be 0.4, 0.5, or 0.6. This setting ensures that the reduction in flow rate matches the change in the pumping speed of the molecular pump caused by the increase in chamber pressure, thereby ensuring the relative stability of the throttle valve opening and the stability of the etching chamber 10 environment. This avoids turbulence or chamber pressure overshoot in the etching chamber 10, reduces disturbance to particulate matter within the etching chamber 10, and ensures that particulate matter can be drawn away in a defined direction, preventing wafer contamination. If the second flow rate L2 is reduced too low, the gas residence time in the second sub-stage S22 will be prolonged, preventing byproducts from being discharged in time and potentially causing them to redeposit on the wafer. If the second flow rate L2 is not reduced sufficiently, combined with the target second chamber pressure F2, the residence time may be too short, which is not conducive to the full action of the desorbed gas.

[0103] In some implementations, the third flow rate L3 is greater than the second flow rate L2.

[0104] It should be noted that the third flow rate L3 is the flow rate of the desorbed gas, and the second flow rate L2 is the flow rate of the etching gas. Since the molecular weight of the etching gas is much larger than that of the desorbed gas, setting the third flow rate L3 to be greater than the second flow rate L2 can ensure that a stable gas flow field is maintained during the gas exchange process, avoid local airflow rebound and eddies, avoid particle resuspension and secondary adhesion caused by overshoot of the throttle valve adjustment or sudden airflow, and reduce the risk of particle adsorption on the wafer surface.

[0105] In some implementations, such as Figure 4 As shown, combined with Figure 3 The transition stage S2 also includes a third sub-stage S23: reducing the flow rate of the etching gas to 0 and continuing to introduce desorption gas into the etching chamber 10 at a fourth flow rate L4; wherein the fourth flow rate L4 is greater than the third flow rate L3.

[0106] It should be noted that the flow rate of the etching gas here can be the second flow rate L2, or it can be an intermediate flow rate where the second flow rate L2 is reduced to 0.

[0107] For example, by introducing a fourth flow rate L4 of desorbed gas while the etching gas flow rate decreases, an equal displacement of the etching gas to the desorbed gas can be achieved, maintaining the stability of the pressure field and keeping the throttle valve opening stable. This avoids particle resuspension and secondary adhesion caused by pressure fluctuations, reducing the risk of particle adsorption on the wafer surface. Setting the fourth flow rate L4 to be greater than the third flow rate L3, i.e., the fourth flow rate L4 has a higher dynamic pressure, can remove residual gas in areas that are difficult to reach by diffusion alone, thus purifying the etching chamber 10.

[0108] In some embodiments, the second environmental parameter further includes: a fifth flow rate L5, which is the flow rate of the desorbed gas introduced into the etching chamber 10 during the desorption stage S3; the fifth flow rate L5 is greater than the fourth flow rate L4.

[0109] For example, since the stability of the chamber pressure depends on the dynamic balance between the total inlet flow rate and the pumping speed of the molecular pump, the desorbed gas gradually increases from the third flow rate L3 in the third sub-stage S23 to the fifth flow rate L5. This allows the flow rate of the desorbed gas to increase in a stepwise manner, ensuring the stability of the throttle valve opening, maintaining a stable gas flow field, avoiding particle resuspension and secondary adhesion caused by throttle valve overshoot or sudden airflow changes, and reducing the risk of particle adsorption on the wafer surface.

[0110] In some implementations, the sum of the third flow rate L3 and the fourth flow rate L4 is equal to the fifth flow rate L5.

[0111] It should be noted that, based on L5=L3+L4, the flow rate of the desorption gas introduced into the etching chamber 10 is ensured to be continuous from the second sub-stage S22 to the third sub-stage S23 and then to the desorption stage S3, so as to avoid residual etching gas being left behind. Through the phenomenon of diffusion backflow, the gas environment in the etching chamber 10 contains a sufficient flow of desorption gas.

[0112] In some embodiments, the product of the fifth flow rate L5 and the relative atomic mass of the desorbed gas is greater than the product of the first flow rate L1 and the relative atomic mass of the etching gas.

[0113] For example, since the drag force of the airflow on the particles is proportional to the dynamic pressure of the airflow and the projected area of ​​the particles, while the density of the gas is proportional to the molecular mass and pressure, the flow velocity is proportional to the flow rate, and the product of the flow rate and the relative atomic mass is proportional to the mass flow rate of the gas, the momentum flux is affected. That is to say, the gas momentum flux in the desorption stage S3 is greater than the gas momentum flux in the etching stage S1. Therefore, when the particulate matter in the etching chamber 10 is falling from the wall, the airflow in the desorption stage S3 can exert a greater upward drag force. This force is sufficient to counteract the gravity of the particulate matter, preventing it from falling and settling onto the wafer surface, but instead continuing to be lifted until it flows to the molecular pump.

[0114] In some implementations, the fifth flow rate L5 ranges from 200 sccm to 800 sccm.

[0115] For example, the fifth flow rate L5 can be 200 sccm, 300 sccm, 400 sccm, 500 sccm, 600 sccm, 700 sccm, or 800 sccm. Setting the range of the fifth flow rate L5 as described above can apply sufficient drag force to the particulate matter remaining after etching, preventing the particulate matter from falling and settling onto the wafer surface. The particulate matter is in a supported state until it flows stably towards the molecular pump in a defined direction, without being resuspended or re-attached due to turbulence.

[0116] In some embodiments, an radio frequency (RF) signal is applied to the RF electrode 40 of the etching chamber 10. The RF signal is a periodic pulse signal; the first power P1, the second power P2, and the third power P3 are the powers during the high-level phase of the RF signal. During the etching phase S1 and / or the transition phase S2, the power during the low-level phase of the RF signal is greater than 0.

[0117] It should be noted that, as Figure 2 As shown, the plasma sheath 3 is a positively charged region with an electric field pointing from the plasma to the wafer. This electric field determines the energy of the ion bombardment and at the same time has a repulsive effect on negatively charged particulate matter, which can suppress the migration of particulate matter to the wafer surface.

[0118] For example, if the power of the low-level phase of the radio frequency signal is equal to 0, the plasma will decay rapidly, the plasma sheath 3 will collapse, the electric field will disappear, and the particulate matter suspended in the plasma will fall and settle onto the wafer surface, causing contamination.

[0119] By setting the power of the low-level stage of the radio frequency signal to be greater than 0 in the etching stage S1 and / or the transition stage S2, it is equivalent to maintaining a low-density plasma with low-level power. The plasma sheath 3 still exists and will not collapse. It can apply a repulsive force to the negatively charged particulate matter in the etching stage S1 and / or the transition stage S2 to prevent the particulate matter from settling to the wafer surface by gravity or airflow disturbance.

[0120] In some implementations, the power range of the low-level stage of the radio frequency signal is 100W to 600W in any of the etching stage S1, the first sub-stage S21, and the second sub-stage S22.

[0121] For example, the power range of the low-level phase of the radio frequency signal is 100W, 200W, 300W, 400W, 500W, or 600W.

[0122] By setting the power range of the low-level stage of the radio frequency signal in any of the etching stages S1, the first sub-stage S21, and the second sub-stage S22, sufficient electric field strength can be provided to ensure that the plasma sheath 3 does not collapse and maintain a stable plasma sheath 3 structure. It can also apply a repulsive force to negatively charged particulate matter in the etching stages S1, the first sub-stage S21, and the second sub-stage S22 to prevent particulate matter from settling onto the wafer surface by gravity or airflow disturbance.

[0123] The following section uses four sets of particle defect images as examples to illustrate the comparison of experimental results obtained using different plasma etching processes for obtaining particle defect images.

[0124] like Figure 5 and Figure 6 The images shown are particle defect maps obtained under the conditions of an etching process that involves periodic cleaning or replacement of the sputtering material, and where the power is 0 during the low-level phase of the RF signal. However, as shown... Figure 7A and Figure 7B The particle defect map obtained by using the plasma etching process described in this application, i.e., when a transition stage is added between the etching stage and desorption stage, is as follows: Figure 8A and Figure 8B The image shown is a particle defect map obtained using the plasma etching process of this application, where the power range of the low-level stage of the radio frequency signal in etching stage S1, first sub-stage S21, and second sub-stage S22 is 100W~600W.

[0125] For example, as shown in Tables 1 and 2, these are the detection results of particle defect maps obtained when the plasma process lasts for 100 s.

[0126] Table 1

[0127] Table 2

[0128] Refer to Tables 1 and 2, and Figure 5 , Figure 6 , Figure 7A and Figure 7B , able to obtain Figure 7A and Figure 7B The plasma etching process described in this application results in a significantly reduced number of particulate contaminants on the wafer surface compared to... Figure 5 and Figure 6 The particulate contaminants on the wafer surface obtained by the traditional plasma etching process are significantly reduced, and the uniformity of particle distribution is also improved.

[0129] Understandably, the above experimental results demonstrate that by adding a transition stage S2 between the etching stage S1 and the desorption stage S3, and by adopting a step-like transition process in the transition stage S2, it is possible to achieve synchronous and stable switching of power and pressure. This avoids the large-scale peeling off of loosened particles due to inertial forces caused by a sudden drop in ion bombardment energy during the process. At the same time, the step-like increase in chamber pressure avoids strong airflow disturbances caused by sudden pressure changes. Airflow disturbances prevent the accidental peeling off and resuspension of particles attached to the chamber walls and component surfaces, thereby reducing the risk of particle contamination on the wafer surface during the process.

[0130] Refer to Tables 1 and 2, and Figure 5 , Figure 6 , Figure 8A and Figure 8B , able to obtain Figure 8A and Figure 8B To utilize the plasma etching process described in this application, the power range during the low-level phase of the S1 RF signal in the etching stage is 100W~600W. This results in a reduction in the number of particulate contaminants on the wafer surface compared to... Figure 5 and Figure 6 The particulate contaminants on the wafer surface obtained by the conventional plasma etching process are further reduced, and the uniformity of particle distribution is also further improved.

[0131] Understandably, the above experimental results demonstrate that the power range of the low-level stage of the radio frequency signal can provide sufficient electric field strength to ensure that the plasma sheath 3 does not collapse and maintain a stable plasma sheath 3 structure. It can apply a repulsive force to the negatively charged particulate matter during the etching stage S1 to prevent the particulate matter from settling onto the wafer surface by means of gravity or airflow disturbance.

[0132] In some implementations, refer to Figure 9 and combined Figure 4 ,in, Figure 9 The solid lines represent line graphs showing the change in particle number with radio frequency time using conventional plasma etching processes. The dashed lines represent line graphs showing the change in particle number with radio frequency time using the plasma etching process of this application, where the power range of the low-level stage of the radio frequency signal in etching stage S1, the first sub-stage S21, and the second sub-stage S22 is 100W~600W. The radio frequency times of 25h, 50h, 75h, 100h, and 150h are used as examples for illustration.

[0133] It is understandable that, within each time period, the number of particulate contaminants on the wafer surface obtained using the plasma etching process of this application is lower than the number of particulate contaminants on the wafer surface obtained using the conventional plasma etching process. In other words, the plasma etching process of this application can achieve continuous and uninterrupted control of particulate contamination during the etching process. The power range of the low-level stage of the radio frequency signal can provide sufficient electric field strength to ensure that the plasma sheath 3 does not collapse and maintains a stable plasma sheath 3 structure. It can apply a repulsive force to the negatively charged particulate matter in the etching stage S1, the first sub-stage S21, and the second sub-stage S22 to prevent the particulate matter from settling to the wafer surface by gravity or airflow disturbance. The addition of a transition stage S2 between the etching stage S1 and the desorption stage S3, and the step transition process of the transition stage S2 can achieve a smooth switching of power and pressure. This avoids the large-scale peeling off of loosened particles under the action of inertial force due to the sudden drop in ion bombardment energy during the process. The step-increasing chamber pressure avoids strong airflow disturbance caused by pressure change. The airflow disturbance prevents the accidental peeling off and resuspension of particles attached to the chamber wall and component surface, thereby reducing the risk of particulate contamination on the wafer surface during the process.

[0134] like Figure 1As shown, some embodiments of this application also provide a plasma etching apparatus 100, including an etching chamber 10, a gas delivery system 20, a pressure control system 30, a radio frequency electrode 40, and a first controller 50. The etching chamber 10 is configured to accommodate a wafer; the gas delivery system 20 is configured to deliver etching gas and / or desorption gas into the etching chamber 10; the pressure control system 30 is configured to control the chamber pressure within the etching chamber 10; the radio frequency electrode 40 is configured to receive radio frequency signals and, based on the radio frequency signals, apply radio frequency power to the etching chamber 10; the first controller 50 is configured to control the gas delivery system 20, the pressure control system 30, and the radio frequency electrode 40 to execute the plasma etching method provided in any of the above embodiments. Therefore, the first controller 50 provided in this application has all the beneficial effects of the plasma etching method provided in any of the above embodiments, and will not be elaborated further here.

[0135] For example, the specific structure and function of each subsystem in the plasma etching apparatus 100 described above are as described in the foregoing content, and will not be repeated here.

[0136] Some embodiments of this application also provide a control method for a plasma etching apparatus 100, the plasma etching apparatus 100 including an etching chamber 10, a gas delivery system 20, a gas pressure control system 30, and a radio frequency electrode 40; combined with Figure 3 The control method includes: During the etching stage S1, the air pressure control system 30 adjusts the chamber pressure in the etching chamber 10 to the first chamber pressure F1, and controls the radio frequency electrode 40 to apply the first power P1 to the etching chamber 10 to etch the wafer placed in the etching chamber 10.

[0137] During the transition phase S2, the control air pressure control system increases the chamber pressure in the etching chamber 10 from the first chamber pressure F1 to the second chamber pressure F2 in a stepwise manner.

[0138] In the desorption stage S3, the control gas pressure control system 30 adjusts the chamber pressure in the etching chamber 10 to the second chamber pressure F2, and controls the radio frequency electrode 40 to apply the second power P2 to the etching chamber 10 to perform desorption treatment on the wafer; wherein, the second power P2 is less than the first power P1.

[0139] For example, the above control method can be executed by the plasma etching apparatus 100, specifically by the control device installed in the plasma etching apparatus 100, or by a host computer that is communicatively connected to the plasma etching apparatus 100.

[0140] For example, the above control method ensures the stability of the equipment state of the plasma etching equipment 100 through precise coordinated control of each subsystem, and ensures the uniformity of the etching rate. At the same time, the stepped increase in chamber pressure avoids strong airflow disturbance caused by pressure change. Airflow disturbance prevents accidental peeling and resuspension of particles attached to the chamber wall and component surface, reduces the risk of particle contamination on the wafer surface during the process, and ensures that the particulate matter always moves stably in a certain direction without backflow or stagnation, thus ensuring the "self-cleaning" capability of the etching chamber 10.

[0141] In some embodiments, the control method further includes: during the transition phase S2, controlling the power of the etching chamber 10 to decrease in a stepwise manner from a first power P1 to a second power P2.

[0142] For example, the stepwise decrease in control power ensures a smooth transition of ion energy, avoids the "charge effect" caused by charge accumulation on the wafer surface, and compensates for the change in ionization rate caused by the increase in pressure, thus preventing the large-scale sputtering of loosened particles due to inertial forces caused by the sudden drop in ion bombardment energy.

[0143] This application also provides a plasma etching method, including an etching stage S1 and a desorption stage S3. For example... Figure 1 As shown, and in combination Figure 3 The etching stage S1 includes: sending a radio frequency signal to the radio frequency electrode in the etching chamber to etch the wafer placed in the etching chamber 10; the radio frequency signal has a first power P1; the desorption stage S3 includes: reducing the power of the radio frequency signal from the first power P1 to a second power P2 to desorb the wafer; wherein the radio frequency signal is a periodic pulse signal, the first power P1 and the second power P2 are the power of the high-level phase of the radio frequency signal, and in the etching stage S1, the power of the low-level phase of the radio frequency signal is greater than 0.

[0144] The plasma etching method can be performed by the aforementioned plasma etching apparatus 100.

[0145] It should be noted that, referring to Figure 2 As described above, the plasma sheath 3 is a positively charged region with an electric field pointing from the plasma towards the wafer. This electric field determines the energy of the ion bombardment and simultaneously exerts a repulsive effect on negatively charged particulate matter, inhibiting its migration to the wafer surface. If the power of the low-level phase of the radio frequency signal is zero, the plasma will rapidly decay, causing the plasma sheath 3 to collapse, the electric field to disappear, and the particulate matter suspended in the plasma to fall and settle onto the wafer surface, causing contamination.

[0146] For example, in the plasma etching method described above, by setting the power of the low-level stage of the radio frequency signal to be greater than 0 in the etching stage S1, it is equivalent to maintaining a low-density plasma with low-level power, ensuring the existence of the plasma sheath 3, that is, the plasma sheath 3 will not collapse, and can apply a repulsive force to the negatively charged particulate matter in the etching stage S1, so as to prevent the particulate matter from settling to the wafer surface by means of gravity or airflow disturbance.

[0147] Specifically, refer to Figure 5 , Figure 6 , Figure 8A and Figure 8B In the plasma etching process, the power of the low-level stage of the radio frequency signal in the etching stage S1 is set to be greater than 0, for example, the power range is 100W~600W, resulting in... Figure 8A and Figure 8B The number of particles shown in the particle defect diagram is compared to Figure 5 and Figure 6 In plasma etching, setting the power of the low-level stage of the radio frequency signal in the etching stage S1 to 0 significantly reduces the number of particles in the particle defect image. In other words, in the above plasma etching method, setting the power of the low-level stage of the radio frequency signal in the etching stage S1 to be greater than 0 is beneficial for controlling the number of particles and thus reducing the risk of contamination.

[0148] In some embodiments, during the etching stage S1, the chamber pressure of the etching chamber 10 is a first chamber pressure F1; between the etching stage S1 and the desorption stage S3, the plasma etching method further includes a transition stage S2, which includes: increasing the chamber pressure of the etching chamber 10 from the first chamber pressure F1 to a second chamber pressure F2 in a stepwise manner, and reducing the power of the high-level stage of the radio frequency signal from a first power P1 to a second power P2; wherein, during the transition stage S2, the power of the low-level stage of the radio frequency signal is greater than 0.

[0149] For example, the chamber pressure in the control transition phase S2 increases in a stepwise manner, avoiding strong airflow disturbances caused by sudden pressure changes. These airflow disturbances prevent accidental peeling and re-suspension of particles attached to the chamber walls and component surfaces, reducing the risk of wafer surface particle contamination during the process. Simultaneously, in the control transition phase S2, the power of the low-level stage of the RF signal is greater than 0, which enhances the efficiency of particle count control, further reducing the risk of wafer surface particle contamination.

[0150] In some embodiments, refer to Figure 2 and combined Figure 3 During the etching stage S1 and / or the transition stage S2, the power range of the low-level stage of the radio frequency signal is 100W~600W.

[0151] For example, the power range of the low-level phase of the radio frequency signal is 100W, 200W, 300W, 400W, 500W, or 600W.

[0152] By setting the power range of the low-level phase of the radio frequency signal during the etching stage S1 and / or transition stage S2, sufficient electric field strength can be provided to ensure that the plasma sheath 3 does not collapse during the etching stage S1 and / or transition stage S2, maintaining a stable plasma sheath 3 structure. This allows the plasma sheath 3 to exert a repulsive force on negatively charged particulate matter, preventing it from settling onto the wafer surface by gravity or airflow disturbance.

[0153] The control methods provided in some embodiments of this application are applicable to the plasma etching apparatus 100 described above, and the plasma etching apparatus 100 can perform the plasma etching method provided in any of the above embodiments. Therefore, the control methods provided in this application also have all the beneficial effects provided in any of the above embodiments, which will not be elaborated here.

[0154] Embodiments of this application also provide a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the control method provided in any of the above embodiments. Therefore, the computer-readable storage medium provided in this application possesses all the beneficial effects of the control methods provided in any of the above embodiments, and will not be elaborated upon here.

[0155] This application also provides a computer program product, which includes computer program code or instructions. When the computer program code or instructions are run on a computer, the control method in the control method embodiment of this application is executed.

[0156] Furthermore, this application also provides a chip including a processor. A memory for storing a computer program is provided independently of the chip, and the processor is used to execute the computer program stored in the memory so that the control method in the control method embodiment of this application is executed.

[0157] Furthermore, the chip may also include a communication interface. The communication interface may be an input / output interface or an interface circuit, etc. Furthermore, the chip may also include a memory.

[0158] It should be understood that the processor in the embodiments of this application can be an integrated circuit chip with the ability to process signals. In implementation, the steps of the above method embodiments can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. A general-purpose processor can be a microprocessor or any conventional processor.

[0159] The memory in the embodiments of this application can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. Volatile memory can be random access memory (RAM), which serves as an external cache. By way of example, but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), and synchronous link dynamic memory (SLDRAM).

[0160] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA, or other programmable logic device, discrete gate or transistor logic device, or discrete hardware component, the memory can be integrated into the processor.

[0161] It should also be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0162] The above description is merely a specific implementation of this application, but the scope of protection of this application is not limited thereto. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the scope of protection of this application.

Claims

1. A plasma etching method, characterized in that, include: The etching stage includes: etching a wafer placed in an etching chamber under first environmental parameters; the first environmental parameters include a first power and a first chamber pressure; The transition phase includes: increasing the chamber pressure of the etching chamber from the first chamber pressure to the second chamber pressure in a stepwise manner; The desorption stage includes: performing desorption treatment on the wafer under a second environmental parameter; the second environmental parameter includes a second power and a second chamber pressure, wherein the second power is less than the first power.

2. The plasma etching method according to claim 1, characterized in that, The step of increasing the chamber pressure of the etching chamber from the first chamber pressure to the second chamber pressure in a stepped manner includes: The first sub-stage includes: increasing the chamber pressure of the etching chamber from the first chamber pressure to the third chamber pressure, wherein the chamber pressure of the etching chamber is maintained at the third chamber pressure for a first preset time; The second sub-stage includes: increasing the chamber pressure of the etching chamber from the third chamber pressure to the second chamber pressure.

3. The plasma etching method according to claim 1 or 2, characterized in that, The transition phase further includes: reducing the power of the etching chamber from the first power to the second power in a stepped manner.

4. The plasma etching method according to claim 3, characterized in that, The step of reducing the power of the etching chamber from the first power to the second power in a stepped manner includes: The first sub-stage includes: reducing the power of the etching chamber from a first power to a third power, wherein the power of the etching chamber is maintained at the third power for a second preset time; The second sub-stage includes reducing the power of the etching chamber from the third power to the second power.

5. The plasma etching method according to claim 4, characterized in that, The ratio of the third power to the sum of the first power and the second power ranges from 0.4 to 0.6; and / or, The ratio of the pressure in the third chamber to the sum of the pressures in the first chamber and the second chamber is in the range of 0.4 to 0.

6.

6. The plasma etching method according to any one of claims 2 to 5, characterized in that, The first environmental parameter further includes: a first flow rate, which is the flow rate of the etching gas introduced into the etching chamber during the etching stage; The first sub-stage further includes: maintaining the flow rate of the etching gas at the first flow rate; The second sub-stage further includes: reducing the flow rate of the etching gas from the first flow rate to the second flow rate, and introducing the desorption gas at a third flow rate.

7. The plasma etching method according to claim 6, characterized in that, The ratio of the second flow rate to the first flow rate is in the range of 0.4 to 0.

6.

8. The plasma etching method according to claim 6 or 7, characterized in that, The third flow rate is greater than the second flow rate.

9. The plasma etching method according to any one of claims 6 to 8, characterized in that, The transition phase also includes: Third sub-stage: Reduce the flow rate of the etching gas to 0, and continue to introduce the desorbed gas into the etching chamber at a fourth flow rate; The fourth flow rate is greater than the third flow rate.

10. The plasma etching method according to claim 9, characterized in that, The second environmental parameter also includes: a fifth flow rate, which is the flow rate of the desorbed gas introduced into the etching chamber during the desorption stage; The fifth flow rate is greater than the fourth flow rate.

11. The plasma etching method according to claim 10, characterized in that, The sum of the third flow rate and the fourth flow rate equals the fifth flow rate.

12. The plasma etching method according to claim 10 or 11, characterized in that, The product of the fifth flow rate and the relative atomic mass of the desorbed gas is greater than the product of the first flow rate and the relative atomic mass of the etching gas.

13. The plasma etching method according to any one of claims 10 to 12, characterized in that, The range of the fifth flow rate is 200 sccm to 800 sccm.

14. The plasma etching method according to claim 4 or 5, characterized in that, The radio frequency electrodes in the etching chamber are subjected to a radio frequency signal, which is a periodic pulse signal; The first power, the second power, and the third power are the power during the high-level phase of the radio frequency signal; During the etching phase and / or the transition phase, the power of the low-level phase of the radio frequency signal is greater than 0.

15. The plasma etching method according to claim 14, characterized in that, During the etching stage, the first sub-stage, and the second sub-stage, the power range of the low-level stage of the radio frequency signal is 100W~600W.

16. The plasma etching method according to claim 14 or 15, characterized in that, The radio frequency signal is a bias radio frequency signal, the first power ranges from 5000W to 33000W, the second power ranges from 100W to 600W, and the third power ranges from 1000W to 15000W.

17. The plasma etching method according to claim 14 or 15, characterized in that, The radio frequency signal is a source radio frequency signal, the first power ranges from 1000W to 15000W, the second power ranges from 100W to 600W, and the third power ranges from 500W to 8000W.

18. The plasma etching method according to any one of claims 2 to 17, characterized in that, The pressure range of the first chamber is 10mT to 30mT, the pressure range of the second chamber is 100mT to 500mT, and the pressure range of the third chamber is 50mT to 250mT.

19. A plasma etching apparatus, characterized in that, include: The etching chamber is configured to accommodate the wafer; A gas delivery system is configured to deliver etching gas and / or desorption gas into the etching chamber; A pneumatic control system is configured to control the chamber pressure within the etching chamber; The radio frequency electrode is configured to receive a radio frequency signal and apply radio frequency power to the etching chamber based on the radio frequency signal; A first controller is configured to control the gas delivery system, the gas pressure control system, and the radio frequency electrode to perform the method as described in any one of claims 1 to 18.

20. A control method, characterized in that, For use in plasma etching equipment, the plasma etching equipment includes an etching chamber, a gas delivery system, a gas pressure control system, and radio frequency electrodes; The method includes: During the etching stage, the air pressure control system adjusts the chamber pressure in the etching chamber to a first chamber pressure, and the radio frequency electrode applies a first power to the etching chamber to etch the wafer placed in the etching chamber. During the transition phase, the air pressure control system controls the chamber pressure in the etching chamber to increase stepwise from the first chamber pressure to the second chamber pressure. During the desorption stage, the air pressure control system adjusts the chamber pressure in the etching chamber to the second chamber pressure, and the radio frequency electrode applies a second power to the etching chamber to perform desorption treatment on the wafer; wherein the second power is less than the first power.

21. The control method according to claim 20, characterized in that, The method further includes: during the transition phase, controlling the power of the etching chamber to decrease in a stepwise manner from the first power to the second power.

22. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores instructions that, when executed on a computer, enable the computer to perform the method as described in claim 20 or 21.

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