Two-stage pressure-regulated plasma etching and cleaning equipment and wafer processing method

Abstract

The present application discloses a dual-stage pressure-regulated plasma etching and cleaning equipment and a wafer processing method, wherein the equipment includes a main chamber, a remote plasma source, a sub-chamber, a vacuum pump, a first valve plate, a second valve plate and a flow limiting plate, wherein a flow limiting hole is provided on the flow limiting plate; the flow limiting hole lays the foundation for the pressure difference, and then cooperates with the second valve plate and the pressure regulating valve to dynamically compensate for the flow fluctuation, thereby achieving millisecond-level precise control of the dual-chamber pressure, and ensuring that both working modes can operate efficiently; the wafer processing method targets polysilicon gates or polysilicon-based structures, and in the degumming stage, free radicals react with etching residues, and the reaction products are all gaseous, which can be extracted by a vacuum pump; through this "etching and degumming integration" collaborative process, the characteristics of polysilicon materials and the advantages of the dual-stage pressure regulation equipment are fully utilized, while ensuring process quality, achieving a balance between efficiency, cost and environmental protection.

Description

Technical Field

[0001] The present application relates to the technical field of wafer manufacturing equipment, and in particular to a dual-stage pressure-regulated plasma etching and cleaning device and a wafer processing method. Background Art

[0002] In semiconductor manufacturing, plasma etching and stripping are key process steps in chip processing. Traditionally, etching and stripping equipment have been designed separately, operating independently. This split architecture, on the one hand, requires two separate sets of equipment to occupy more factory space, increasing procurement costs and site investment. On the other hand, significant time is lost in transferring wafers between different equipment, switching gas environments, and recalibrating process parameters, severely limiting production efficiency. Furthermore, the independent spare parts systems of the two sets of equipment increase management complexity and maintain high maintenance costs.

[0003] With the increasing demand for process integration, the integration of remote plasma source (RPS) and capacitively coupled plasma (CCP) etching systems is becoming a trend. However, CCP etching requires a low pressure environment of 50-100 mTorr to ensure ion directionality, while RPS stripping requires a higher pressure of 300-500 mTorr to increase radical density. Traditional integrated equipment cannot achieve dynamic balance and precise control of the dual pressure domains, resulting in parameter conflicts in the etching and stripping processes. Summary of the Invention

[0004] The purpose of this application is to overcome the deficiencies in the prior art and to provide a dual-stage pressure-regulated plasma etching and cleaning device and a wafer processing method.

[0005] The present application provides a dual-stage pressure-regulated plasma etching and cleaning device, comprising: a main chamber, equipped with a radio frequency power supply for performing a plasma etching process; a remote plasma source for generating active free radicals for degumming; a sub-chamber, connecting the remote plasma source and the main chamber; a vacuum pump, connected to the main chamber, for regulating the gas pressure in the main chamber and connected to the sub-chamber via a bypass branch, wherein a pressure regulating valve is configured in the bypass branch; a first valve plate, provided between the main chamber and the sub-chamber, for dynamically isolating the two chambers; a second valve plate, provided between the main chamber and the sub-chamber, for dynamically isolating the two chambers; and a second valve plate, provided between the main chamber and the sub-chamber. The opening of the second valve plate between the vacuum pumps is adjustable. By adjusting the opening of the second valve plate, the flow conductance between the main chamber and the vacuum pump can be changed, thereby realizing instantaneous control of the pressure. A flow limiting plate is also provided between the main chamber and the sub-chamber, and a flow limiting hole is provided on the flow limiting plate. The flow limiting hole is used to limit the gas flow from the sub-chamber to the main chamber and form a pressure gradient. Through the coordinated action of the bypass branch and the flow limiting plate, a dynamic pressure balance between the high pressure of the sub-chamber and the low pressure of the main chamber can be achieved, so as to support two working modes: etching first and then stripping, and etching while stripping.

[0006] Furthermore, a pneumatic valve is provided in the bypass branch, and the pneumatic valve is connected in parallel with the pressure regulating valve; the pneumatic valve can assist in rapid pressure relief.

[0007] Furthermore, the opening of the second valve plate is linked to the opening of the pressure regulating valve. When the first valve plate is opened, the opening of the second valve plate θ satisfies: θ=k·(P2-P1) / Q P ; Among them, P1 is the target pressure of the main chamber, P2 is the measured pressure of the secondary chamber, Q P is the calibrated pumping speed of the vacuum pump, k is the conductance compensation coefficient, and k is calibrated through simulation experiments.

[0008] Furthermore, the aperture Φ of the flow-limiting hole satisfies: ; Wherein, Q is the inlet flow rate of the remote plasma source, and ρ is the density of the process gas used for debonding.

[0009] Furthermore, the aperture of the flow limiting hole is adjustable; the flow limiting plate is rotatably arranged at the outlet of the sub-chamber, and at least two flow limiting holes with different apertures are provided on the flow limiting plate. The flow limiting plate is rotated so that the flow limiting holes with different apertures are facing the outlet of the sub-chamber, so as to achieve a dynamic balance between different gas flow rates and intra-cavity pressures; a needle valve is also provided at the outlet of the sub-chamber, and the needle tip of the needle valve can be inserted into the flow limiting hole facing the outlet of the sub-chamber, and the cone angle of the needle tip is 55°-65°. The degree of insertion of the needle tip can change the degree of opening of the flow limiting hole; during operation, according to the type of process gas used for degumming and the actual flow rate, a suitable flow limiting hole is selected, and the insertion of the needle valve can better adapt to the cross-process mode.

[0010] Furthermore, the dual-stage pressure-regulated plasma etching and cleaning equipment also includes a filter, which is installed at the output end of the RF power supply and the remote plasma source to eliminate frequency band interference between the RF source and the microwave source.

[0011] Furthermore, a bent air pipe is provided in the sub-chamber, one end of the bent air pipe is connected to the side extraction branch, and the other end faces the cavity wall or bottom wall of the sub-chamber, and the other end of the bent air pipe serves as the entrance of the side extraction branch and is arranged away from the remote plasma source; at least two levels of baffles are also provided in the sub-chamber, and the at least two levels of baffles are nested, any baffle is provided with an opening, and the openings on any two adjacent baffles are far away from each other; the outlet of the sub-chamber connecting to the main chamber is arranged within the innermost primary baffle; the other end of the bent air pipe is arranged between the outermost primary baffle and the cavity wall of the sub-chamber; the bent air pipe and the baffle cooperate to prevent active free radicals from entering the side extraction branch.

[0012] Furthermore, the sub-chamber is arranged in a trumpet shape, and the further away from the remote plasma source, the larger the inner diameter of the sub-chamber; when the active free radicals flow toward the outlet of the sub-chamber, the flow velocity gradually decreases, which can increase the residence time of the active free radicals in the sub-chamber, and is also beneficial for the active free radicals to be more evenly distributed around the outlet of the sub-chamber when the first valve plate is closed; the side of the first valve plate close to the sub-chamber is arranged to have a concave surface, and when the first valve plate is opened, the concave surface can guide the airflow to rush toward the main chamber, thereby reducing the diffusion loss of the active free radicals.

[0013] Furthermore, the etching and stripping working mode includes repeated cycles, the duration of any cycle is T, and any cycle includes an etching period and a cleaning period, the duration of the etching period is T1, and the duration of the cleaning period is T2, T1:T2≥85%:15%; during the etching period, the etching process gas is continuously introduced into the main chamber, the first valve plate is closed, the remote plasma source is working, and the pre-generated active free radicals are temporarily stored in the sub-chamber; during the cleaning period, the etching gas is stopped, the first valve plate is opened, and the active free radicals enter the main chamber, which can remove by-products and increase the etching rate.

[0014] The present application also provides a wafer processing method, which is implemented using the above-mentioned two-stage pressure-regulated plasma etching and cleaning equipment, wherein the wafer is a polysilicon gate or a polysilicon-based structure;

[0015] The wafer processing method includes the following steps: etching the wafer in a main chamber, introducing a mixed gas containing HBr and NF3, or containing SF6 and C4F8, as an etching process gas into the main chamber to generate by-products containing silicon halides or carbon fluorine polymers; the proportion of halogen atoms in the etching process gas is not less than 50%; introducing a mixed gas containing O2 and H2O, or containing NF3 and O2, as a degumming process gas into a remote plasma source to excite the plasma to generate active free radicals; the volume proportion of oxygen-containing components in the degumming process gas is not less than 40%; after etching is completed, allowing the active free radicals to enter the main chamber to achieve degumming on the wafer surface and decomposition of etching residues, and the etching residues are converted into at least one of gaseous substances SiO2, SiF2O, COF2, and HF and are pumped away by a vacuum pump.

[0016] The present application provides a dual-stage pressure-regulated plasma etching and cleaning device, comprising a main chamber, a remote plasma source, a sub-chamber, a vacuum pump, a first valve plate, a second valve plate, and a flow-limiting plate, wherein a flow-limiting hole is provided on the flow-limiting plate; first-stage pressure regulation is achieved by the flow-limiting hole, through which the gas flow from the sub-chamber to the main chamber can be limited, thereby establishing and maintaining a basic pressure gradient between the low-pressure main chamber and the high-pressure sub-chamber, preventing the high pressure of the sub-chamber from directly impacting the main chamber, while ensuring that active free radicals can stably flow into the main chamber; second-stage pressure regulation is achieved by the linkage of the second valve plate and the pressure-regulating valve; when the first valve plate is opened, the second valve plate balances the main chamber pressure by fine-tuning the opening, and the pressure-regulating valve stabilizes the sub-chamber pressure by adjusting the suction force of the bypass branch, and the two work together to limit the gas flow; by laying a foundation for the pressure difference through the flow-limiting hole, and then cooperating with the second valve plate and the pressure-regulating valve to dynamically compensate for flow fluctuations, it is possible to achieve millisecond-level precise control of the dual-chamber pressure, which is beneficial to the process stability of etching and degumming, and can also extend the life of the equipment and ensure that both working modes can operate efficiently. The dual-stage pressure-regulated plasma etching and cleaning equipment provided by the present application solves the problem of large factory space occupation and high procurement and site investment caused by the separation of traditional etching and stripping equipment through the integrated design of remote plasma source, sub-chamber, and main chamber. It eliminates the process of transferring wafers between different equipment and recalibrating parameters, which can reduce time loss and improve production efficiency. At the same time, with the synergistic effect of the vacuum pump, bypass branch and pressure regulating valve (regulating the pressure of the sub-chamber), the first valve plate (dynamically isolating the two chambers), the second valve plate (regulating the pressure of the main chamber) and the flow limiting plate (limiting the gas flow to form a pressure gradient), it effectively solves the pressure parameter conflict between the etching and stripping processes in the integrated equipment. When the first valve plate is opened, the pressure increase trend when the high-pressure gas in the sub-chamber flows into the main chamber is offset, making the pressure fluctuation of the main chamber smaller and ensuring the stability of the working pressure in the main chamber. The dual-stage pressure-regulated plasma etching and cleaning equipment provided by the present application supports dual working modes (etching first and then stripping and etching while stripping), which can adapt to more diverse process requirements.

[0017] The present application also provides a wafer processing method, which is implemented using the above-mentioned two-stage pressure-regulated plasma etching and cleaning equipment. The wafer processed is a polysilicon gate or a polysilicon-based structure. A mixed gas containing HBr and NF3, or containing SF6 and C4F8, is used as the etching process gas, and a mixed gas containing O2 and H2O, or containing NF3 and O2, is used as the degumming process gas. During the degumming stage, free radicals react with the etching residues, and the reaction products are all gaseous. The gaseous products can be pumped out by a vacuum pump to avoid secondary deposition. Through this "integrated etching and degumming" collaborative process, the characteristics of polysilicon materials and the advantages of the two-stage pressure regulation equipment are fully utilized. While ensuring process quality, a balance between efficiency, cost and environmental protection is achieved. It is particularly suitable for the processing of polysilicon structures in advanced semiconductor processes that require extremely high precision and compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic structural diagram of a dual-stage pressure-regulated plasma etching and cleaning device provided in this application;

[0019] Figure 2 A schematic structural diagram of another dual-stage pressure-regulated plasma etching and cleaning device provided in this application;

[0020] Figure 3 for Figure 2 The top view of the structure of the sub-chamber in the dual-stage pressure-regulated plasma etching and cleaning equipment is shown. DETAILED DESCRIPTION

[0021] To make the above-mentioned objects, features, and advantages of the present application more clearly understood, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings. The following description sets forth many specific details to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways than those described herein, and those skilled in the art can make similar improvements without violating the scope of the present application. Therefore, the present application is not limited to the specific embodiments disclosed below.

[0022] The present application provides a two-stage pressure-regulated plasma etching and cleaning device, comprising: a main chamber 11, equipped with a radio frequency power supply for performing a plasma etching process; a remote plasma source 1, for generating active free radicals for degumming; a sub-chamber 12, connecting the remote plasma source 1 and the main chamber 11; a vacuum pump 2, connected to the main chamber 11, for regulating the gas pressure of the main chamber 11, and connected to the sub-chamber 12 via a bypass branch, wherein a pressure regulating valve 3 is configured in the bypass branch; a first valve plate 21, arranged between the main chamber 11 and the sub-chamber 12, for dynamically isolating the two chambers; a second valve plate 22, arranged between the main chamber 11 and the vacuum pump 2, the opening of the second valve plate 22 being adjustable, and by adjusting the opening and closing angle of the second valve plate 22, the flow conductance between the main chamber 11 and the vacuum pump 2 can be changed, thereby achieving instantaneous control of the pressure.

[0023] Among them, a flow limiting plate is also provided between the main chamber 11 and the sub-chamber 12, and a flow limiting hole is opened on the flow limiting plate. The flow limiting hole is used to limit the gas flow from the sub-chamber 12 to the main chamber 11 and form a pressure gradient; through the synergistic effect of the bypass branch and the flow limiting plate, a dynamic pressure balance between the high pressure of the sub-chamber and the low pressure of the main chamber can be achieved, so as to support two working modes: etching first and then stripping, and etching while stripping.

[0024] For details, please refer to Figure 1 In the illustrated embodiment, the sub-chamber 12 is disposed above the main chamber 11, and the remote plasma source 1 is disposed above the sub-chamber 12. The remote plasma source 1, the sub-chamber 12, and the main chamber 11 are stacked vertically.

[0025] Continue to refer to Figure 1 The main chamber 11 is provided with a first gas inlet 5, and the etching process gas can enter the main chamber 11 through the first gas inlet 5. The main chamber 11 is also provided with a gas outlet, and the gas outlet of the main chamber 11 is connected to the vacuum pump 2.

[0026] Continue to refer to Figure 1 The main chamber 11 is equipped with an RF power supply (400-800W, 13.56MHz), which is connected to the carrier and / or the chamber wall. During the etching process, the RF power supply ionizes the etching reaction gas into a plasma. The generated positive ions bombard the wafer surface, achieving physical sputtering and chemical reactions. Simultaneously, the vacuum pump 2 operates at a constant pumping speed (e.g., 2000L / s) to maintain the operating pressure (e.g., 50-100mTorr) within the main chamber 11.

[0027] Continue to refer to Figure 1 A second valve plate 22 is mounted on the vacuum pump 2. During the etching process, the second valve plate 22 adjusts its opening in real time based on feedback from the pressure sensor (both the main chamber 11 and the sub-chamber 12 are equipped with pressure sensors). By varying the conductance, the pressure fluctuation within the main chamber 11 is controlled within ±3 mTorr, thereby ensuring uniform plasma density.

[0028] Continue to refer to Figure 1 The remote plasma source 1 is equipped with a second gas inlet 6, through which the process gas for resist removal enters the quartz chamber of the remote plasma source 1. The remote plasma source 1's power supply (1000-1500W, 2.45GHz) operates, generating an electromagnetic field within the quartz chamber that ionizes the gas molecules, generating plasma. High-energy electrons collide with the gas molecules, triggering a dissociation reaction and producing active free radicals. The outlet of the remote plasma source 1 is connected to the inlet of the sub-chamber 12. The generated free radicals can be temporarily stored in the sub-chamber 12.

[0029] Continue to refer to Figure 1 The secondary chamber 12 is connected to the vacuum pump 2 via a bypass line, which is equipped with a pressure regulating valve 3. When the remote plasma source 1 is operating, the pressure regulating valve 3 maintains a relatively small opening. The vacuum pump 2 continuously pumps air, in conjunction with a pressure sensor, to stabilize the pressure in the secondary chamber 12 (e.g., 500 mTorr, higher than the pressure in the main chamber 11).

[0030] Continue to refer to Figure 1 A first valve plate 21 is provided at the outlet of the secondary chamber 12. The outlet of the secondary chamber 12 communicates with the main chamber 11. When the first valve plate 21 is closed, the two chambers are isolated; when the first valve plate 21 is opened, the two chambers are unobstructed. Under the action of the pressure difference, the active free radicals in the secondary chamber 12 will enter the main chamber 11 through the flow restriction plate, chemically react with the etching residue in the main chamber 11, and achieve cleaning.

[0031] In one embodiment, after completing one stage of etching, the first air inlet 5 is closed, and the second air inlet 6 is opened wider, beginning the full-scale stripping phase. The first valve plate 21 opens, allowing the active free radicals within the sub-chamber 12 to flow into the main chamber 11. Simultaneously, the pressure regulating valve 3 is opened wider, working in conjunction with the vacuum pump 2 to increase suction, thereby preventing a sudden pressure drop in the sub-chamber 12 and thereby preventing a disruption in the subsequent supply of free radicals. After stripping is complete, the pressure regulating valve 3 is reset to a smaller opening, and the vacuum pump 2 removes any residual gas within the sub-chamber 12 through a bypass line, preparing for the next round of free radical storage.

[0032] Furthermore, a flow limiting plate is provided at the outlet of the sub-chamber 12. When the first valve plate 21 is opened, the active free radicals and gases in the sub-chamber 12 can enter the main chamber 11 through the flow limiting hole on the flow limiting plate. The flow limiting hole can limit the gas flow rate and cooperate with the bypass branch to form a pressure gradient between the main chamber (low pressure) and the sub-chamber (high pressure). When the first valve plate 21 is opened, the flow limiting hole controls the amount of active free radicals and gases flowing from the sub-chamber 12 into the main chamber 11 per unit time, thereby preventing the high pressure of the sub-chamber from directly impacting the main chamber 11 and causing a sudden pressure rise. At the same time, it can ensure that the active free radicals enter the main chamber 11 at a stable flow rate and act evenly on the wafer surface. In addition, the flow limiting hole can also filter large particle impurities in the air flow, reducing their contamination of the main chamber 11.

[0033] Specifically, the first-stage pressure regulation is achieved by a flow-limiting orifice. This orifice limits the flow of gas from the secondary chamber 12 to the main chamber 11, establishing and maintaining a basic pressure gradient between the low-pressure main chamber and the high-pressure secondary chamber. This prevents the secondary chamber's high pressure from directly impacting the main chamber, while ensuring a stable flow of active free radicals into the main chamber.

[0034] Second-stage pressure regulation is achieved through the linkage between the second valve plate 22 and the pressure-regulating valve 3. When the first valve plate 21 is open, the second valve plate 22 balances the main chamber pressure by fine-tuning its opening, while the pressure-regulating valve 3 stabilizes the secondary chamber pressure by adjusting the suction force of the bypass branch; the two work together to limit gas flow.

[0035] By establishing a pressure difference foundation through the flow-limiting hole and dynamically compensating for flow fluctuations with the second valve plate 22 and the pressure-regulating valve 3, millisecond-level precise control of the dual-chamber pressure can be achieved, which is beneficial to the process stability of etching and degumming, and can extend the life of the equipment and ensure that both working modes can operate efficiently.

[0036] In one embodiment, the dual-stage pressure-regulated plasma etching and cleaning equipment provided in the present application operates in an etching-first-then-stripping working mode.

[0037] The etching-before-stripping working mode includes an etching stage (independent low-pressure etching in the main chamber 11), a transition stage (the connection between the end of etching and the start of stripping) and a stripping stage (dual-chamber coupled stripping).

[0038] Etching stage:

[0039] The first valve plate 21 is closed, the second valve plate 22 is fully opened (opening degree 100%), the pressure regulating valve 3 is closed, the vacuum pump 2 runs at a constant speed, and the main chamber 11 is evacuated to 50 mTorr by the vacuum pump 2 to establish a low-pressure etching environment (taking about 10 seconds).

[0040] The remote plasma source 1 and the sub-chamber 12 are in a standby state, and the pressure in the sub-chamber 12 is balanced with the atmospheric pressure.

[0041] Open the first gas inlet 5 and introduce a mixed gas containing HBr and NF3 (volume ratio 3:1, total flow rate 100 sccm). At the same time, start the RF power supply (power 400W). The mixed gas is excited into a plasma, in which Br· and F· ions directionally bombard the surface of the wafer (polysilicon gate structure), causing the following etching reaction:

[0042] Si+2HBr→SiBr2+H2↑;

[0043] Si+2NF3→SiF2+2N2↑;

[0044] Silicon-containing halide byproducts SiBr2 and SiF2 are produced.

[0045] During this process, the second valve plate 22 will dynamically fine-tune the opening (fluctuation range 100%±5%) according to the feedback from the main chamber pressure sensor to stabilize the pressure of the main chamber 11 at 50±1mTorr (it takes 60s to complete the etching).

[0046] When the etching time ends, the RF power supply and the first air inlet 5 are turned off, the first valve plate 21 remains closed, the second valve plate 22 remains fully open, and the vacuum pump 2 continues to pump air to remove the residual etching reaction gas and by-products in the main chamber 11 (taking 2 seconds).

[0047] Transition phase:

[0048] When the etching time ends, the second gas inlet 6 is opened to introduce a mixed gas containing O2 and H2O (volume ratio 4:1, total flow rate 200 sccm) into the remote plasma source 1. The remote plasma source 1 is started (power 600 W). O2 and H2O are ionized into active free radicals such as O· and OH·, which enter the sub-chamber 12 through the pipeline.

[0049] At the same time, the pressure regulating valve 3 is opened to 60% of its opening, and the sub-chamber 12 is connected to the vacuum pump 2 through the bypass branch. After 15 seconds of adjustment, the pressure in the sub-chamber 12 is stabilized at 500 mTorr.

[0050] After the pressure in the secondary chamber 12 stabilizes, the second valve plate 22 is gradually closed from fully open to 30% open (taking 50 ms), and the pumping rate of the main chamber 11 is reduced to prepare for the subsequent pressure jump. At this time, the pressure in the main chamber 11 is still maintained at 50±2 mTorr.

[0051] Glue removal stage:

[0052] The first valve plate 21 opens, allowing the O· and OH· reactive free radicals in the secondary chamber 12 to enter the main chamber 11 through the restrictor. The restrictor limits the flow rate, allowing only 5% of the total flow from the secondary chamber 12 to enter the main chamber 11. The pressure in the main chamber 11 begins to rise due to the influx of gas. Simultaneously, the second valve plate 22 is further closed to 15%, reducing the pumping rate to match the intake flow rate. Within 200ms, the pressure in the main chamber 11 steadily rises from 50mTorr to 300mTorr.

[0053] Active free radicals react with the silicon halide byproducts remaining from etching, and the following reaction occurs:

[0054] SiBr2+2O・→SiO2↑+Br2↑;

[0055] SiF2+2OH・→SiF2O↑+H2O↑;

[0056] Generates gaseous products such as SiO2, Br2, SiF2O, and removes the residual photoresist on the wafer surface (the C element in the photoresist reacts with O・ to generate CO2). The reaction lasts for 30 seconds.

[0057] When the degumming time ends, the remote plasma source 1 and the second air inlet 6 are turned off, the first valve plate 21 is closed, the pressure regulating valve 3 is fully opened, and the sub-chamber 12 is quickly depressurized to 100 mTorr through the bypass branch (taking 5 seconds); the second valve plate 22 is gradually fully opened, and the main chamber 11 is evacuated through the vacuum pump 2 to remove the reaction products, completing the entire etching-then-degumming process.

[0058] In this process, stripping can be performed directly after etching because the equipment is an integrated design, eliminating the need to transfer wafers. Furthermore, the O· and OH· active free radicals used for stripping can specifically decompose the silicon-containing halide byproducts and photoresist produced by etching.

[0059] Through the coordinated regulation of the first valve plate 21, the second valve plate 22, the pressure regulating valve 3 and the flow limiting hole, rapid switching between the etching low pressure (50mTorr) and the stripping medium pressure (300mTorr) is achieved, ensuring that the pressure is stable and without drastic fluctuations, which can effectively avoid damage to the wafer.

[0060] It should be noted that the transition phase can be considered the pre-generation phase for active free radicals. In practice, free radical pre-generation can be performed simultaneously with the etching process by closing the first valve plate 21 and properly utilizing the second valve plate 22 and pressure regulating valve 3 to coordinate the process gas pressures on both sides. Pre-generating free radicals while etching can improve process efficiency.

[0061] In another embodiment, the dual-stage pressure-regulated plasma etching and cleaning equipment provided in the present application operates in an etching-while-stripping working mode.

[0062] Specifically, the etching and stripping working mode operates in a repeated cycle, with a single cycle duration of T=20s, wherein the etching period duration is T1=17s, and the cleaning period duration is T2=3s (T1 and T2 are duration values). In each cycle, the main chamber 11 and the sub-chamber 12 achieve dynamic pressure balance and process connection through structural coordination.

[0063] More specifically, the etching period:

[0064] The first valve plate 21 is closed, and the main chamber 11 is physically isolated from the sub-chamber 12; the second valve plate 22 is opened 80% to maintain a stable pumping rate in the main chamber 11; the pressure regulating valve 3 is opened 60%, and the pressure in the sub-chamber 12 is controlled at 400mTorr through the bypass branch; the vacuum pump 2 runs at a constant speed to ensure the pressure in both chambers.

[0065] A mixed gas containing SF6 and C4F8 (volume ratio 2:1, total flow rate 120 sccm) is introduced into the main chamber 11 through the first gas inlet 5. A radio frequency power supply (power 500W) excites plasma, and F· ions bombard the wafer (polysilicon-based structure) in a directionally controlled manner, causing the following etching reaction:

[0066] Si+2SF6→SiF4↑+2S2F2↑.

[0067] During the etching process, C4F8 provides a fluorocarbon polymer protective film to prevent excessive etching on the wafer side. The reaction generates SiF4 (gaseous) and fluorocarbon polymer (solid residue).

[0068] The pressure in the main chamber 11 is stabilized at 60 mTorr (the second valve plate 22 can be fine-tuned according to pressure fluctuations to ensure that the pressure fluctuation is always less than 3%).

[0069] During the etching process, the remote plasma source 1 introduces a mixed gas containing NF3 and O2 (volume ratio 1:2, total flow rate 150sccm) through the second gas inlet 6, ionizing to generate F· and O· active free radicals. The free radicals enter the sub-chamber 12 through the pipeline and are temporarily stored in the sub-chamber 12.

[0070] Cleanout period:

[0071] After the etching period, the first air inlet 5 is immediately closed, and the first valve plate 21 is opened to 100% within 50ms; the second valve plate 22 is quickly closed to 20% (reducing the pumping rate of the main chamber) to offset the pressure jump trend caused by the influx of high-pressure gas in the sub-chamber; the opening of the pressure regulating valve 3 is maintained at 60%, the pressure of the sub-chamber 12 is maintained at 400mTorr, and the pressure of the main chamber is steadily increased to 150mTorr within 200ms.

[0072] The free radicals temporarily stored in the sub-chamber 12 enter the main chamber 11 through the flow restriction hole. The flow restriction hole can limit the gas flow to the main chamber 11 so that the sub-chamber 12 maintains a high pressure of 400mTorr, while allowing only no more than 5% of the gas to penetrate into the main chamber 11 to avoid contaminating the etching plasma.

[0073] The free radicals react with the fluorocarbon polymer residues generated by etching as follows:

[0074] (C x F y ) n +2nO・→nCO2↑+(ny / 2)F2↑.

[0075] At the same time, free radicals can react with SiF4 that has not been extracted to generate SiF2O (gaseous), thereby quickly removing by-products in the main chamber 11 and on the surface of the wafer to prevent their accumulation from affecting the etching accuracy.

[0076] 100 ms before the end of the purge period, the first valve plate 21 is closed, the second valve plate 22 returns to 80% opening, and the pressure in the main chamber 11 drops back to 60 mTorr within 300 ms.

[0077] The first air inlet 5 is reopened, the radio frequency power supply is turned on, and the etching period of the next cycle is entered.

[0078] In the etching-while-stripping mode, the interaction between etching and stripping is achieved through "time-sharing isolation and instantaneous connection." During the etching phase, the main chamber independently maintains a low etching pressure (60mTorr), while the secondary chamber pre-stores a high concentration of free radicals (400mTorr). A flow-limiting orifice ensures high pressure in the secondary chamber while preventing free radicals from prematurely infiltrating the main chamber and disrupting the etching plasma. During the purge phase, the etching gas supply is suspended, and a brief connection is used to introduce free radicals into the main chamber. After the byproducts are quickly removed, etching resumes immediately, without wafer transfer. The linkage between the second valve plate 22 and the pressure regulating valve 3 ensures smooth pressure switching between the main and secondary chambers.

[0079] Compared to the traditional etch-first, then strip mode, the etch-while-strip mode prevents the accumulation of byproducts (such as fluorocarbon polymers) on the wafer surface by removing them in real time. This ensures exposure of a fresh reaction surface while suppressing polymer deposition, thereby maintaining a high etch rate. The integrated equipment also eliminates the time it takes to transfer wafers between the etching and stripping equipment. Two-stage pressure regulation resolves the parameter conflict between the low-pressure etching and high-pressure stripping in the integrated equipment, reducing equipment footprint and maintenance complexity. Furthermore, the dynamic pressure balance design helps improve etching uniformity, meeting the demands of high-precision wafer processing.

[0080] In summary, the dual-stage pressure-regulated plasma etching and cleaning equipment provided by the present application solves the problems of large factory space occupation and high procurement and site investment caused by the separation of traditional etching and stripping equipment through the integrated design of remote plasma source 1, sub-chamber 12, and main chamber 11. It eliminates the process of transferring wafers between different equipment and recalibrating parameters, which can reduce time loss and improve production efficiency. At the same time, with the synergistic effect of vacuum pump 2, bypass branch and pressure regulating valve 3 (regulating the pressure of sub-chamber 12), first valve plate 21 (dynamically isolating the two chambers), second valve plate 22 (regulating the pressure of main chamber 11) and flow restrictor (limiting gas flow to form a pressure gradient), it effectively solves the pressure parameter conflict between etching and stripping processes in the integrated equipment. When the first valve plate 21 is opened, it offsets the pressure increase trend when the high-pressure gas in the sub-chamber flows into the main chamber, making the main chamber pressure fluctuation smaller and ensuring the stable working pressure in the main chamber. The dual-stage pressure-regulated plasma etching and cleaning equipment provided by the present application supports dual working modes (etching first and then stripping and etching while stripping), which can adapt to more diverse process requirements.

[0081] Optionally, a pneumatic valve 4 is further provided in the bypass branch, and the pneumatic valve 4 is connected in parallel with the pressure regulating valve 3; the pneumatic valve 4 can assist in rapid pressure relief.

[0082] For details, please refer to Figure 1 In the illustrated embodiment, the pneumatic valve 4 is located in the bypass branch connecting the sub-chamber 12 and the vacuum pump 2, and is connected in parallel with the pressure regulating valve 3 (i.e., their inlets are connected to the bypass port of the sub-chamber 12, and their outlets are connected to the intake port of the vacuum pump 2). The pneumatic valve 4 is fixed to the bypass branch pipeline via a pipe flange, enabling rapid on / off control.

[0083] Pneumatic valve 4 is primarily used to assist the bypass branch in rapid pressure relief. When switching process modes (e.g., switching from stripping to etching), opening pneumatic valve 4 can instantly reduce the pressure in sub-chamber 12, thereby preventing residual free radicals from reacting with the etching gas to form harmful byproducts.

[0084] The additional pneumatic valve 4 also supports emergency pressure relief mode (such as forced opening when the pressure in the sub-chamber 12 exceeds the preset maximum value) and safety isolation mode (closing together with the pressure regulating valve 3 can isolate the bypass branch to prevent gas backflow during maintenance, or lock the pressure in the event of process abnormalities).

[0085] The provision of the pneumatic valve 4 can compensate for the shortcoming of slow pressure relief speed when only the pressure regulating valve 3 is provided in the bypass branch.

[0086] In one embodiment, the opening of the second valve plate 22 is linked to the opening of the pressure regulating valve 3. When the first valve plate 21 is opened, the opening θ of the second valve plate 22 satisfies: θ=k·(P2-P1) / Q P Wherein, P1 is the target pressure of the main chamber 11, P2 is the measured pressure of the sub-chamber 12 (P1, P2 are numerical values, specifically pressure values), Q P is the calibrated pumping speed of the vacuum pump, k is the conductance compensation coefficient, and k is calibrated through simulation experiments.

[0087] The above formula is based on the need for pressure balance between the main and auxiliary chambers when the first valve plate 21 is open. Specifically, when the first valve plate 21 is open, the high-pressure gas in the auxiliary chamber flows into the low-pressure main chamber. This pressure increase needs to be offset by adjusting the opening of the second valve plate 22 and changing the suction capacity.

[0088] The core logic is that the gas inflow is positively correlated with the pressure difference (P2-P1), and the gas extraction volume is positively correlated with the valve plate opening θ and the pumping speed Q. P Then, the conductance compensation coefficient k is used to correct the deviations of pipeline resistance, valve roughness, etc. in the actual equipment, and finally the result is derived.

[0089] The function of this formula is to accurately calculate the opening of the second valve plate 22, to ensure that the pressure in the main chamber can be maintained or changed steadily after the first valve plate 21 is opened, to avoid drastic pressure fluctuations caused by the influx of gas into the secondary chamber, and to ensure the stability of the low-pressure working environment.

[0090] Wherein, P1 is the process setting value (i.e., the preset pressure of the main chamber 11 is P1); P2 is measured in real time by the pressure sensor (monitoring the pressure of the auxiliary chamber 12) (i.e., the actual pressure of the auxiliary chamber 12 is P2); Q P It is the rated pumping speed marked on the nameplate of vacuum pump 2.

[0091] k is the conductance compensation coefficient (0.5-0.8) calibrated experimentally. The engineering approach to obtaining k requires multiple sets of controlled experiments. The core is to infer the correction coefficient from actual pressure fluctuations to eliminate the impact of individual equipment differences (such as pipe curvature, valve inner wall roughness, chamber flow field disturbances, etc.) on theoretical calculations. The specific steps are as follows:

[0092] Close the first valve plate 21 to ensure that the main and auxiliary chambers are completely isolated;

[0093] The etching process gas is introduced into the main chamber 11, and the main chamber pressure is stabilized at the target value P1 through the second valve plate 22 and the vacuum pump 2. The initial opening θ0 of the second valve plate 22 is recorded at this time, and the vacuum pump 2 is maintained at the calibrated pumping speed Q P Constant speed operation.

[0094] The process gas for debonding is introduced into the secondary chamber 12, and the pressure of the secondary chamber is stabilized at P2 through the pressure regulating valve 3. The pressure of the secondary chamber is monitored and recorded in real time using a capacitive pressure sensor. Then, the first valve plate 21 is quickly opened to allow the high-pressure gas in the secondary chamber to flow into the main chamber, and the instantaneous peak value ΔP of the main chamber pressure is recorded. max (i.e. the maximum difference between the actual P2 and the set P1).

[0095] According to the initial opening θ0, the measured pressure difference ΔP max And pumping speed Q P , substitute into the formula k=(θ0·Q P ) / ΔP max Perform calculations (e.g. θ0=50%=0.5, Q P =2000L / s, ΔP max =30mTorr, then k=(0.5×2000) / 30≈33.3, where the value is a dimensionless coefficient and only reflects the correction ratio).

[0096] Repeat the above steps three times, each time adjusting the secondary chamber pressure P2 (e.g., 400mTorr, 500mTorr, 600mTorr) and the main chamber target pressure P1 (e.g., 60mTorr, 50mTorr, 40mTorr) to obtain multiple sets of k values. Then, use the least squares method to fit the pressure stability curve, remove outliers, and take the average to finally determine the k value of the device.

[0097] Substitute the calibrated k value into the formula θ=k·(P2-P1) / Q P , tested in actual processes. When the first valve plate 21 is open, if the main chamber pressure fluctuation is less than the target value (e.g., ≤±3mTorr), the k value is valid. If the fluctuation exceeds the limit, additional sets of experiments and recalibration are required until the accuracy requirements are met.

[0098] The k value obtained by this method can accurately correct the deviation between the theoretical conductance and the actual equipment, ensuring the accuracy of the opening adjustment of the second valve plate 22.

[0099] In a specific embodiment, the target pressure P1 of the main chamber 11 is 50 mTorr, the measured pressure P2 of the auxiliary chamber 12 is 400 mTorr, and the calibrated pumping speed Q of the vacuum pump 2 is P=2000L / s, experimentally calibrated k = 0.62. Substituting this into the formula yields θ = 0.62 × (400 - 50) / 2000 = 0.1085 (i.e., 10.85°). The first valve plate 21 opens, allowing gas from the secondary chamber to flow into the main chamber. The second valve plate 22 adjusts the pumping capacity by opening at 10.85°. The actual monitored pressure fluctuation in the main chamber is only ±2 mTorr. This formula demonstrates precise pressure balancing and significant reliability.

[0100] In one embodiment, the aperture Φ of the flow-limiting hole satisfies: ; Wherein, Q is the inlet flow rate of the remote plasma source 1, and ρ is the density of the process gas used for degumming.

[0101] The above formula is derived from Poiseuille's law in gas dynamics, which converts the relationship between gas flow Q, pressure difference (ΔP), and viscosity (η) into a relationship with density (ρ). According to the circular hole flow equation Q∝Φ 4 ΔP / η, under constant pressure difference conditions, combined with the theoretical relationship between gas viscosity and density η∝ρvλ (v is the average molecular velocity, λ is the mean free path), derives Φ 4 ∝ρQ; then through the fourth root equivalent transformation and experimental data fitting (testing the relationship between the flow rate and pore size of O2, N2, and Ar under semiconductor process parameters), it is found that Φ is It is linear, and the final calibration coefficient is 0.08. It can accurately match the coupling requirements of gas properties and mechanical design in actual working conditions.

[0102] The function of this formula is to provide an accurate calculation basis for the aperture of the flow-limiting hole under different process conditions, thereby improving the pressure control accuracy and reducing the pressure fluctuation of the sub-chamber 12.

[0103] Q (the inlet gas flow rate of remote plasma source 1) is measured in real time using a gas flowmeter (e.g., a mass flowmeter). Generally, Q is the process setpoint. ρ is determined by the type of gas. The weighted average density of the mixed gas can be calculated based on its volume fraction.

[0104] In a specific embodiment, the process gas for resist removal is O2 (ρ=1.429g / L), and the gas flow rate Q of the remote plasma source 1 is 200sccm. Substituting into the formula Φ=0.08× ≈0.95mm. In actual applications, this aperture stabilizes the pressure of the sub-chamber 12 at 300mTorr (fluctuation ±1%) and only allows 4.8% of the gas to penetrate into the main chamber 11 (meeting the requirement of ≤5%). When the inlet flow rate of the remote plasma source 1 is adjusted to 50sccm, re-substituting it into the formula yields Φ≈0.47mm, at which point the pressure fluctuation of the sub-chamber is still controlled within ±1%; if a fixed aperture of 0.95mm is used, the pressure fluctuation reaches ±6% after the flow rate changes, and the proportion of gas penetrating into the main chamber increases to 12%, which will interfere with the etching process. This shows that the formula can accurately adapt to different flow rates and is remarkably reliable.

[0105] Optionally, the aperture of the flow restriction hole is adjustable.

[0106] Conventional fixed-diameter flow restrictors can only adapt to a preset flow environment, with a narrow adaptation range. When the flow rate of the process gas for desmearing exceeds this range, the fixed-diameter flow restrictor will be unable to maintain the pressure in the secondary chamber 12, which can easily lead to contamination of the main chamber 11 or plasma quenching.

[0107] The flow-limiting orifice is designed with an adjustable aperture, dynamically matching the optimal aperture to process gases of varying flow rates and densities, thereby widening the process window. Furthermore, precise aperture adjustment minimizes pressure fluctuations in the secondary chamber 12, further improving pressure control accuracy.

[0108] In one embodiment, the flow restrictor comprises three circular orifice plates, each with a flow restrictor hole of varying diameters. The secondary chamber 12 is connected to the main chamber 11 via a pipe, which is fitted with a slot into which the circular orifice plates are inserted for installation. During operation, the circular orifice plates can be manually replaced based on flow requirements to adapt to the specific working environment. This is simple to operate and requires no complex actuators.

[0109] In another embodiment, the flow limiting plate includes two metal plates each having a semicircular hole. The two metal plates overlap, and the diameter of the flow limiting hole can be changed by sliding one of the metal plates to change the overlapping area of ​​the holes.

[0110] This application does not limit the specific method of adjusting the aperture of the flow-limiting hole.

[0111] In one embodiment, the flow limiting plate is rotatably disposed at the outlet of the sub-chamber 12, and at least two flow limiting holes with different apertures are provided on the flow limiting plate. The flow limiting plate is rotated so that the flow limiting holes with different apertures are facing the outlet of the sub-chamber 12, so as to achieve a dynamic balance between different gas flow rates and intra-cavity pressures.

[0112] In this embodiment, a flow restrictor plate is rotatably mounted between the secondary chamber 12 and the main chamber 11 via a rotatable support. The flow restrictor plate has a circular shape and is larger than the outlet of the secondary chamber 12. The flow restrictor plate is provided with at least two flow restricting holes of varying diameters (e.g., 0.5 mm, 1.5 mm, and 2.5 mm). These holes are spaced circumferentially, and each hole is precisely aligned with the center of the outlet of the secondary chamber 12 after rotation, thereby achieving an open gas path. During use, the flow restrictor plate is rotated manually or by a drive assembly (e.g., a stepper motor) based on the inlet flow rate of the remote plasma source 1 (e.g., 5 sccm, 200 sccm, 500 sccm) and the density of the process gas used for resist removal, so that the appropriate flow restricting hole is aligned with the outlet of the secondary chamber. For example, a small hole (0.5 mm) is used to maintain high pressure in the secondary chamber at low flow rates (5 sccm), while a large hole (2.5 mm) is used to prevent excessive pressure at high flow rates (500 sccm).

[0113] By setting a rotatable limiting plate, the switching process does not require interruption of the process, and the structure is simple and easy to maintain.

[0114] In another embodiment, a needle valve is further provided at the outlet of the sub-chamber 12, and the needle tip of the needle valve can be inserted into the flow limiting hole facing the outlet of the sub-chamber 12. The cone angle of the needle tip is 55°-65°. By controlling the insertion degree of the needle tip, the opening degree of the flow limiting hole can be changed.

[0115] In this embodiment, the sub-chamber 12 is connected to the main chamber 11 through a pipe, and a flow limiting plate is fixedly installed in the pipe, and a flow limiting hole with a fixed aperture (such as 1.5mm) is provided on the flow limiting plate. A needle valve is also provided in the pipe, and the needle tip of the needle valve is processed to a cone angle of 55°-65° (preferably 60°). The axis of the needle tip is coaxial with the center of the flow limiting hole. The depth of the needle tip inserted axially into the flow limiting hole can be controlled by a driving component (such as a cylinder, an electric cylinder, etc.). When in use, the insertion depth of the needle tip is adjusted according to the inlet flow rate of the remote plasma source 1 and the density of the process gas for degumming: at low flow rates (such as 5sccm), the insertion is deeper (such as 1.2mm), leaving only an open aperture of 0.3mm to maintain the high pressure of the sub-chamber; at high flow rates (such as 500sccm), the needle tip is pulled out (inserted to 0mm), and the full aperture of 1.5mm is used to circulate to avoid a sudden pressure rise.

[0116] By combining a single flow restriction with a needle valve for fine-tuning, continuous flow regulation can be achieved across a wide range. The tapered needle tip forms a linear seal with the orifice wall, enhancing regulation accuracy. Furthermore, the insertion of the needle tip scrapes away polymer from the orifice, enabling self-cleaning of the orifice.

[0117] In another embodiment, the flow limiting plate is rotatably disposed at the outlet of the sub-chamber 12, and at least two flow limiting holes with different apertures are provided on the flow limiting plate. At the same time, a needle valve is also provided at the outlet of the sub-chamber 12. During operation, a suitable flow limiting hole is selected according to the type and actual flow rate of the process gas used for degumming, and the needle valve is inserted to better adapt to the cross-process mode.

[0118] This implementation combines a dual adjustment mechanism: a rotatable flow restrictor plate and a needle valve. The restrictor plate is rotatably mounted in the pipeline via a swivel support. Multiple flow restrictor holes of varying diameters (e.g., 0.5mm, 1.2mm, 2.0mm, and 3.0mm) are evenly distributed along its circumference, each corresponding to a different flow range. The needle valve is mounted perpendicular to the central axis of the pipeline, with a 60° needle tip angle. The insertion depth of the needle valve (e.g., 0-3mm) can be controlled by an electric cylinder. When in use, the system first selects the closest flow-limiting orifice based on the process gas type (such as O2, NF3) and flow range; for example, a small orifice (0.5mm) is selected for low flow (5-50sccm), a medium orifice (1.2mm) is selected for medium flow (50-200sccm), and a large orifice (3.0mm) is selected for high flow (200-500sccm); then, the needle valve accurately adjusts the degree of opening based on real-time pressure feedback. For example, when a 1.2mm orifice is selected and the flow rate is 100sccm, the needle tip is inserted to 0.8mm, so that the actual open aperture is dynamically adjusted to 0.4mm, achieving targeted pressure control.

[0119] Through the dual mechanism of "coarse adjustment + fine adjustment", it takes into account both a wide flow range and high-precision control. It can not only quickly switch to adapt to different process gases, but also compensate for the discreteness of the flow limiting hole through the needle valve, making the equipment compatible with both etching first and then stripping and etching while stripping.

[0120] Optionally, the limiting plate is made of high-purity silicon carbide (SiC) material.

[0121] SiC has extremely high temperature resistance (melting point approximately 2700°C) and chemical inertness, making it resistant to long-term corrosion from active free radicals such as O and F during the stripping process. Furthermore, with a hardness of 9.5 Mohs, SiC effectively resists erosion and wear from etching byproducts (such as silicon halides), extending its service life compared to traditional stainless steel stator plates.

[0122] Optionally, the surface smoothness of the flow limiting plate is Ra less than 0.05 μm, which can reduce polymer adhesion and lower the risk of the flow limiting hole being blocked.

[0123] Optionally, the needle tip surface is covered with a diamond coating with a thickness of 5-10 μm.

[0124] The diamond coating boasts a hardness of up to 10 Mohs and excellent chemical stability. It is unreactive with process gases used for desmearing (such as NF3 and O2) and etch residues, and can withstand the friction generated by frequent contact between the needle tip and the flow restriction (friction coefficient less than 0.1). Furthermore, the diamond coating's low surface energy (less than 30 mN / m) reduces polymer deposition, preventing loss of adjustment accuracy due to needle tip adhesion and ensuring long-term reliability of aperture fine-tuning.

[0125] Optionally, the dual-stage pressure-regulated plasma etching and cleaning equipment provided in the present application further includes a filter, which is installed at the output end of the RF power supply and the remote plasma source 1 to eliminate frequency band interference between the RF source and the microwave source.

[0126] The filter, designed as an LC resonant circuit, is installed between the RF power supply and the output of the remote plasma source 1. Its core function is to selectively attenuate signals in specific frequency bands while allowing the RF power supply's fundamental frequency signal to pass through unattenuated, ensuring stable excitation of the plasma in the main chamber 11. It also suppresses high-frequency harmonics generated by the microwave source from entering the RF circuit, while also preventing stray harmonics of the RF signal from interfering with the microwave source. The filter is connected to the power supply output via a coaxial cable and features a modular design for easy maintenance and replacement.

[0127] After eliminating the frequency band interference, the plasma density fluctuation in the main chamber 11 is smaller, which helps to improve the uniformity of the etching rate; it can also improve the free radical generation efficiency of the remote plasma source 1 and improve the degumming rate.

[0128] Adding a filter can ensure the synchronous excitation of RF and microwave to support the etching and stripping process mode.

[0129] Optionally, a bent air pipe 31 is provided in the sub-chamber 12, one end of the bent air pipe 31 is connected to the bypass branch, and the other end faces the cavity wall or bottom wall of the sub-chamber 12, and the other end of the bent air pipe 31 serves as the entrance of the bypass branch and is arranged away from the remote plasma source 1.

[0130] For details, please refer to Figure 2 In the illustrated embodiment, the bent air pipe 31 is made of 316L stainless steel, with an inner diameter of 8-12 mm and a wall thickness of 1-1.5 mm. The bent air pipe 31 is generally J-shaped (in other embodiments, it can also be L-shaped, S-shaped, spiral-shaped, etc.), including a first horizontal section connecting the bypass branch and extending horizontally toward the axis of the sub-chamber 12, a vertical section, and a second horizontal section extending horizontally toward the chamber wall. The vertical section connects the first horizontal section and the second horizontal section. The bend of the bent air pipe 31 adopts a rounded transition to avoid airflow dead zones caused by sharp angles. The bent air pipe 31 is arranged downward as a whole, away from the remote plasma source 1.

[0131] By extending the gas path through the curved structure, free radicals such as O· and F· can recombine due to collisions with the chamber walls during transport, thereby reducing the concentration of active species entering the bypass branch. The flow resistance created by the multiple bends can also create a pressure gradient within the sub-chamber 12 (for example, when the bypass branch is evacuated through the pressure regulating valve 3 and vacuum pump 2, the flow resistance of the curved gas pipe 31 maintains the pressure in the sub-chamber 12 at 500mTorr, while the inlet pressure of the bypass branch is 480mTorr, creating a pressure differential of 20mTorr, which prevents the pressure in the main chamber 11 from being affected by the bypass), ensuring that the active gas preferentially flows into the main chamber 11 rather than the bypass branch.

[0132] Reducing the amount of corrosive free radicals (such as F·) entering the vacuum pump 2 can also extend the replacement cycle of the pump oil and reduce the corrosion rate of the internal components of the pump body.

[0133] Optionally, at least two levels of baffles 32 are provided in the sub-chamber 12, and the at least two levels of baffles 32 are nested. An opening is provided on any baffle 32, and the openings on any two adjacent baffles 32 are far away from each other; the outlet of the sub-chamber 12 connecting to the main chamber 11 is provided in the innermost primary baffle 32; the inlet of the bypass branch is connected to the channel between the outermost primary baffle 32 and the wall of the sub-chamber 12.

[0134] For details, please refer to Figure 2 and Figure 3 In the illustrated embodiment, a two-stage baffle 32 is provided in the sub-chamber 12. The baffle 32 is made of 316L stainless steel. The two-stage baffle 32 is nested in a concentric ring shape. The height of each baffle 32 matches the height of the sub-chamber 12 (the top and bottom walls of the sub-chamber 12 can be connected to ensure that the gas only flows in the channel formed by the baffle 32, or the height of the baffle 32 can be 2 / 3 of the height of the sub-chamber, so that the active free radicals and the process gas for degumming can quickly fill the sub-chamber 12 and can quickly enter the main chamber 11 under the action of the pressure difference).

[0135] Continue to refer to Figure 3 Any baffle 32 is provided with an opening for gas to flow into the next level channel, and the openings on the two adjacent baffles 32 are directed away from each other (the opening of the inner baffle 32 faces upward, and the opening of the outer baffle 32 faces downward).

[0136] Continue to refer to Figure 3 The inner baffle 32 surrounds the outlet of the sub-chamber 12 (the outlet is located in the central area surrounded by the baffle 32) and is connected to the outlet of the remote plasma source 1. An annular channel is formed between the outermost baffle 32 and the cavity wall of the sub-chamber 12, and the annular channel is connected to the bent gas pipe 31.

[0137] The addition of baffles 32 allows the active free radicals generated by the remote plasma source 1 to enter the secondary chamber 12. To flow toward the bypass branch, they must first pass through the inner baffle 32 and then the outer baffle 32. Because the openings of the two baffles 32 intersect, the free radicals must change direction multiple times and recombine during collisions with the baffles 32, making it difficult for the free radicals to reach the bypass inlet. Free radicals flowing toward the main chamber 11, on the other hand, can flow along the area formed by the inner baffle 32 and directly enter the main chamber through the secondary chamber outlet.

[0138] By extending the path of active free radicals to the side extraction branch through the labyrinth structure, the loss of free radicals drawn away by the vacuum pump 2 can be greatly reduced, which not only improves the utilization rate of free radicals, but also helps to maintain the high pressure and high concentration free radical environment of the sub-chamber 12. It can also avoid corrosion caused by the reaction between free radicals entering the side extraction branch and the pump body, which is beneficial to extending the life of the equipment.

[0139] In a specific embodiment, referring to Figure 2 and Figure 3 A bent air pipe 31 and at least two levels of baffles 32 are provided in the sub-chamber 12, and the other end of the bent air pipe 31 is arranged between the outermost level baffle 32 and the cavity wall of the sub-chamber 12; the bent air pipe 31 and the baffle 32 cooperate to prevent active free radicals from entering the side extraction branch.

[0140] In this embodiment, the coordinated design of the bent air pipe 31 and the multi-stage baffle 32 forms a double-barrier structure. During operation, after entering the sub-chamber 12, free radicals such as O· and F· generated by the remote plasma source 1 partially diffuse into the main chamber 11 and partially diffuse into the side pump branch. The presence of the baffle 32 forces the free radicals to make multiple turns, each of which causes some free radicals to collide with the wall of the baffle 21 and become inactivated. Ultimately, only a small number of initial free radicals can reach the side pump inlet. The presence of the bent air pipe 31 causes the remaining free radicals to collide and recombine within the pipe, further reducing the number of free radicals that can enter the pump body. In addition, the flow resistance of the bent air pipe 31 and the throttling effect of the opening of the baffle 32 work together to increase the central pressure of the sub-chamber 12 to be higher than the side pump inlet pressure, forming a radial pressure gradient that can inhibit the diffusion of free radicals into the side pump branch. This can not only improve the utilization rate of free radicals but also reduce the degree of contamination of the side pump.

[0141] Through this dual-blocking mechanism, the contradiction between active particle loss and system contamination in plasma equipment is effectively resolved. It is particularly suitable for advanced semiconductor manufacturing processes that have strict requirements on free radical concentration and purity.

[0142] Optionally, the structures in the sub-chamber 12, such as the sub-chamber 12, the bent air pipe 31, and the baffle 32, are made of materials with a low free radical recombination coefficient, such as high-purity alumina ceramics (Al2O3) with a purity ≥ 99.5%, anodized aluminum treated with a 20μm oxide layer, or 316L stainless steel passivated by a plasma nitriding process.

[0143] The surfaces of these materials are highly chemically inert and have low reactivity with active free radicals such as O· and F·, which can reduce the collision and recombination losses of free radicals on the wall.

[0144] Optionally, the wall surfaces of the sub-chamber 12 , the bent air pipe 31 , the baffle 32 and other structures in the sub-chamber 12 are mirror-polished to make the surface roughness Ra≤0.02 μm.

[0145] The smooth surface can reduce the probability of collision between free radicals and the wall, which is beneficial to prolonging the residence time of active free radicals in the sub-chamber 12, thereby increasing the free radical concentration and ensuring the debonding efficiency.

[0146] Optionally, the sub-chamber 12 is configured to be trumpet-shaped, and the further away from the remote plasma source 1, the larger the inner diameter of the sub-chamber 12; when the active free radicals flow toward the outlet of the sub-chamber 12, the flow rate gradually decreases, which can increase the residence time of the active free radicals in the sub-chamber 12, and is also beneficial for the active free radicals to be more evenly distributed around the outlet of the sub-chamber 12 when the first valve plate 21 is closed.

[0147] For details, please refer to Figure 2 In the illustrated embodiment, the inner diameter of the sub-chamber 12 increases from top to bottom, and the cross-section of the sub-chamber 12 is shaped like a trumpet with a small top and a large bottom. The axis of the trumpet coincides with the output axis of the remote plasma source 1, ensuring symmetrical diffusion of the airflow.

[0148] For example, when active free radicals enter the sub-chamber 12 at an initial velocity of v1 = 50 m / s, according to the continuity equation Q = A·v, the outlet velocity v2 = v1·(D1 / D2)² ≈ 14 m / s, a 72% decrease in flow rate. This reduced flow rate reduces the frequency of free radical collisions with the wall, prolongs the free radical's residence time, and increases their chances of interacting with the wafer.

[0149] In addition, based on the Bernoulli equation, the expansion structure will cause the static pressure to increase, forming a pressure gradient from the inlet to the outlet, thereby inhibiting the reverse diffusion of free radicals and further reducing pressure fluctuations.

[0150] Optionally, a side of the first valve plate 21 close to the secondary chamber 12 is provided with a concave surface. When the first valve plate 21 is opened, the concave surface can guide the airflow to rush toward the main chamber 11, thereby reducing the diffusion loss of active free radicals.

[0151] For details, please refer to Figure 2 In the illustrated embodiment, the bottom surface of the sub-chamber 12 (the side facing away from the remote plasma source 1, near the outlet connecting to the main chamber 11) is concave and curved. The edges of the curved surface smoothly transition with the sidewalls of the sub-chamber 12 through rounded corners, avoiding airflow dead zones caused by sharp angles. The curved surface is made of 316L stainless steel and electropolished to a surface roughness of Ra ≤ 0.01μm. It forms a sealed integral structure with the sidewalls and outlet flange of the sub-chamber 12, and the central axis of the curved surface coincides with the central axis of the outlet of the sub-chamber 12.

[0152] After entering the sub-chamber 12 , the active free radicals generated by the remote plasma source 1 are guided by the concave surface, and the gas flow converges toward the center along the tangent direction of the surface, which can reduce the loss of diffusion toward the side wall of the sub-chamber 12 .

[0153] The arc-shaped path of the curved surface can prolong the residence time of free radicals in the sub-chamber 12, and the centripetal convergence effect makes the free radical concentration distribution around the outlet more uniform. When the first valve plate 21 is opened, the concentrated airflow can quickly and evenly enter the main chamber 11, avoiding incomplete degumming due to insufficient local concentration. The concave curved surface can also reduce the turbulent disturbance in the sub-chamber 12 by guiding the airflow to concentrate toward the outlet, making the pressure fluctuation in the cavity smaller, and providing a stable basis for the coordinated control of the pressure of etching and degumming. In addition, the airflow converged by the curved surface can form a "targeted match" with the flow limiting hole, thereby improving the stability of the gas flow through the flow limiting hole and reducing the risk of blockage of the flow limiting hole due to airflow turbulence.

[0154] In one embodiment, the etching and stripping working mode includes repeated cycles, the duration of any cycle is T, and any cycle includes an etching period and a cleaning period, the duration of the etching period is T1, and the duration of the cleaning period is T2, T1:T2≥85%:15%; during the etching period, the etching process gas is continuously introduced into the main chamber 11, the first valve plate 21 is closed, the remote plasma source 1 is working, and the pre-generated active free radicals are temporarily stored in the sub-chamber 12; during the cleaning period, the etching gas is stopped, the first valve plate 21 is opened, and the active free radicals enter the main chamber 11, which can remove by-products and increase the etching rate.

[0155] The etching and stripping mode operates in a repetitive cycle T, which is repeated at least twice. The etching period T1 accounts for more than 85% of each cycle, and dynamic switching is achieved through the coordination of high-speed components.

[0156] During the etching phase, the main chamber 11 continuously flows with etching process gas, the RF power supply operates, energizes the plasma, and positive ions bombard the wafer surface in a directionally controlled manner, achieving etching. During this phase, the first valve plate 21 is closed, isolating the main and auxiliary chambers. The vacuum pump 2 operates at a constant speed, and the second valve plate 22 is fully open to maintain the main chamber pressure at a predetermined value.

[0157] During the etching period, the remote plasma source 1 introduces a process gas for resist removal to pre-generate active free radicals, which are temporarily stored in the sub-chamber 12 in preparation for the cleaning period.

[0158] When the etching time ends and the cleaning period begins, the first air inlet 5 is closed and the first valve plate 21 is opened. Free radicals can enter the main chamber 11 through the flow restriction hole under the action of the pressure difference and react with the photoresist to achieve cleaning.

[0159] During the cleaning period, in order to maintain different chamber pressures in the main and sub-chambers, it is necessary to adaptively adjust the opening of the second valve plate 22, the opening of the pressure regulating valve 3 and / or the opening of the flow limiting hole according to the monitoring conditions of the pressure sensor to ensure that the main chamber 11 maintains a normal working low pressure (after entering the cleaning period, the main chamber 11 may need to maintain the low pressure of the etching period, or may need to adjust the pressure to adapt to the cleaning reaction), while the sub-chamber 12 maintains the required high pressure for free radical excitation.

[0160] This periodic etching and desizing mode can not only remove by-products in real time (solid by-products generated during the etching process, such as fluorocarbon polymers, if they remain on the wafer surface or the inner wall of the chamber, will cause the etching rate to decrease and the sidewall morphology to be distorted. The continuous insertion of the removal period can control the residual amount of by-products to below 0.1nm through real-time reaction of free radicals), avoid process degradation, ensure the etching rate, and improve the etching uniformity (real-time removal of by-products can avoid the "micro-load effect" caused by local accumulation); it can also eliminate the wafer transfer link (there is no need to transfer the wafer from the etching chamber to the desizing chamber, which can avoid the introduction of particle contamination during the transfer process, and there is no need to recalibrate the pressure and gas parameters), reducing risks and time.

[0161] By distributing T1 over 85% of the cycles, the main chamber 11 maintains low pressure during the etching period and briefly rises to high pressure during the cleaning period. Combined with the high-speed switching of the first valve plate 21 and the second valve plate 22, it can ensure that the pressure fluctuation is less than ±5mTorr, which not only meets the etching requirements for low-pressure plasma, but also adapts to the requirements of degumming for a high-pressure free radical environment, and is compatible with a variety of processes from shallow trench etching to high aspect ratio structure etching.

[0162] In addition, the etching period of more than 85% ensures the continuity and dominance of the etching process, avoids the rate drop or etching profile deformation due to frequent interruptions of etching, ensures the etching depth per unit time, and achieves a dynamic balance of "etching as the main and degumming as the auxiliary".

[0163] The etching-while-stripping mode has the core advantage of "real-time removal of by-products and improved process efficiency and stability", and is widely used in fields with strict requirements on etching accuracy, surface cleanliness and production efficiency.

[0164] For example, in the field of logic chip and memory chip manufacturing, such as FinFET (fin field-effect transistor) and 3D NAND, the etching of high aspect ratio structures (such as deep trenches and contact holes) needs to avoid "etching stagnation" caused by the accumulation of byproducts such as fluorocarbon polymers. The periodic etching-while-removing mode can remove sidewall polymers in real time through O· free radicals, ensuring the verticality and depth uniformity of etching, which is especially suitable for precision processing of 14nm and below nodes.

[0165] For example, in through-silicon via (TSV) etching, the required etch depth is 50-100μm. Traditional step-by-step processes are prone to interruptions due to byproduct clogging of the via. The periodic etching-while-removing mode utilizes F radicals to continuously clean the via walls through a 15% purge period, keeping the via open.

[0166] For example, in the etching of wide bandgap semiconductors such as GaN (gallium nitride) and SiC (silicon carbide), the periodic etching and removal mode can remove the metal nitrides generated by etching in real time (such as GaN generated by GaN etching). x ), prevent it from redepositing on the wafer surface to form a "shadow effect", ensure the resolution of the etched pattern, and improve key parameters such as the device's breakdown voltage and on-resistance.

[0167] The common requirements of these fields are high-precision etching and low residual contamination, and the etching-while-stripping mode perfectly adapts to their requirements for efficiency, cleanliness and process compatibility through periodic collaborative operation in the same chamber.

[0168] Furthermore, to avoid interference between the two process gases during the purge period, the purge period is switched at high speed within 30ms after the etching time is over. The specific process is executed according to the following time slices:

[0169] t=0ms, the first air inlet 5 is closed, cutting off the etching gas source;

[0170] t=2ms, the flow rate of the process gas for resist removal is increased (during the etching period, the flow rate of the process gas for resist removal will be lower than the normal process flow rate, for example, only 60% of the normal flow rate is introduced to avoid generating too many free radicals and aggravating the loss. After entering the purge phase, the flow rate of the process gas for resist removal is increased to the normal flow rate), and high-density free radicals are excited in the sub-chamber 12;

[0171] At T=5ms, the first valve plate 21 opens instantly to 100% opening, injecting the free radicals in the auxiliary chamber 12 into the main chamber 11. At the same time, the second valve plate 22 opens at θ=k·(P2-P1) / Q P The formula is turned down to maintain low pressure in the main chamber and prevent pressure surges. The RF power supply is also turned off to prevent free radicals from being ionized.

[0172] T=25ms, the first valve plate 21 is closed, isolating the high pressure of the secondary chamber;

[0173] T = 28ms, the pneumatic valve 4 is fully opened, and the auxiliary chamber 12 is depressurized to 10mTorr through the bypass branch within 0.3 seconds to ensure that the residual gas is exhausted;

[0174] T=30ms, switching back to the etching period, the etching process gas is reintroduced, the RF power supply is restarted, the second valve plate 22 is restored to full opening, and etching is continued after the main chamber pressure stabilizes.

[0175] The entire process relies on high-speed piezoelectric valves (response time less than 5ms) to achieve millisecond-level action coordination. By periodically removing etching by-products, their accumulation is prevented from causing a decrease in etching rate. At the same time, switching is completed within 30ms without affecting etching continuity, taking into account both efficient etching and real-time degumming needs.

[0176] The present application also provides a wafer processing method, which is implemented using the above-mentioned dual-stage pressure-controlled plasma etching and cleaning equipment. The wafer processing method is targeted at wafers with polysilicon gates or polysilicon-based structures.

[0177] The wafer processing method includes the following steps:

[0178] The wafer is etched in the main chamber 11, and a mixed gas containing HBr and NF3, or containing SF6 and C4F8, is introduced into the main chamber 11 as an etching process gas to generate a by-product containing silicon halide or fluorocarbon polymer;

[0179] The proportion of halogen atoms in the etching process gas is not less than 50%;

[0180] A mixed gas containing O2 and H2O, or containing NF3 and O2, is introduced into the remote plasma source 1 as a process gas for debonding to excite plasma and generate active free radicals;

[0181] The volume proportion of oxygen-containing components in the process gas used for degumming is not less than 40%;

[0182] After etching is completed, active free radicals enter the main chamber 11 to remove the wafer surface and decompose the etching residues. The etching residues are converted into at least one of the gaseous substances SiO2, SiF2O, COF2, and HF and are pumped away by the vacuum pump 2.

[0183] This wafer processing method targets polysilicon gates or polysilicon-based structures (such as shallow trench isolation (STI) and gate etch areas). Polysilicon has a much higher oxidation resistance than Al, Cu, or Co metal interconnect layers. This process targets only polysilicon areas such as STI and gates, avoiding damage to the metal layers. Furthermore, the differential oxidation resistance between polysilicon and metal ensures that the etching process is limited to the target areas. The metal interconnect layers and ultra-low-k dielectrics, protected by masks or inherently corrosion-resistant, are not susceptible to free radical attack.

[0184] The wafer processing method includes an etching stage (main chamber 11) and a stripping stage (remote plasma source 1+main chamber 11).

[0185] Etching stage:

[0186] A mixed gas containing HBr and NF3 (such as HBr:NF3=60:40sccm) or SF6 and C4F8 (such as SF6:C4F8=100:20sccm) is introduced, in which the proportion of halogen atoms (Br, F) is not less than 50%, which can ensure efficient etching of polysilicon.

[0187] The etching reaction is Si+4NF3→SiF4↑+2N2↑+3F2↑.

[0188] During this process, the pressure of the main chamber 11 is maintained at 50-100 mTorr, the RF power is 400-800 W, and a high-density plasma (electron density 10 11 -10 12 cm -3 ), so that F + Br + Ions bombard the polysilicon surface in a directional manner to form silicon-containing halides (SiF4, SiBr4) and fluorocarbon polymers (C x F y ) by-product.

[0189] During the etching phase, a gas mixture containing O₂ and H₂O (e.g., an O₂ flow rate of 100 sccm and an H₂O flow rate of 20 sccm) or NF₃ and O₂ (e.g., an NF₃ flow rate of 50 sccm and an O₂ flow rate of 50 sccm) is introduced into the remote plasma source 1, wherein the oxygen component accounts for no less than 40%. This generates highly reactive free radicals such as O₂, OH₂, and F₂ under excitation by the remote plasma source 1. These highly reactive free radicals are temporarily stored in the sub-chamber 12.

[0190] Glue removal stage:

[0191] After the etching phase is completed, free radicals are injected into the main chamber 11 through the dual-stage pressure control system and react with the etching residues:

[0192] Fluorocarbon polymer: C x F y +O・→CO2↑+F2↑

[0193] Silicon halide: SiF4+2OH → SiO2↑+2HF↑

[0194] Metal residue (if there is trace exposure): Al2O3+6F・→2AlF3↑+3O2↑

[0195] It can be seen that the reaction products are all in gaseous state, and the gaseous products can be pumped out by the vacuum pump 2 to avoid secondary deposition.

[0196] This allows etching and stripping to be performed continuously within the same equipment, eliminating wafer transfer time, reducing single-wafer processing cycles, and improving wafer processing efficiency. Dual-stage pressure regulation improves free radical utilization and reduces process gas consumption for stripping. The dual-stage pressure evenly distributes free radicals, improving stripping uniformity within the wafer and avoiding edge residue issues associated with traditional wet stripping.

[0197] Through this "integrated etching and de-bonding" collaborative process, the characteristics of polysilicon materials and the advantages of dual-stage pressure control equipment are fully utilized, and a balance between efficiency, cost and environmental protection is achieved while ensuring process quality. It is especially suitable for polysilicon structure processing in advanced semiconductor processes that have extremely high requirements for precision and compatibility.

[0198] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A dual-stage pressure-regulated plasma etching and cleaning device, characterized in that: include: A main chamber (11) is provided with a radio frequency power supply for performing a plasma etching process; A remote plasma source (1) for generating active free radicals for adhesive stripping; A secondary chamber (12) communicating with the remote plasma source (1) and the main chamber (11); a vacuum pump (2), connected to the main chamber (11), for regulating the air pressure of the main chamber (11), and connected to the auxiliary chamber (12) via a bypass branch, wherein a pressure regulating valve (3) is provided in the bypass branch; a first valve plate (21), disposed between the main chamber (11) and the secondary chamber (12), for dynamically isolating the two chambers; a second valve plate (22) disposed between the main chamber (11) and the vacuum pump (2); the opening of the second valve plate (22) is adjustable; by adjusting the opening of the second valve plate (22), the flow conductance between the main chamber (11) and the vacuum pump (2) can be changed, thereby achieving instantaneous pressure control; A flow limiting plate is provided between the main chamber (11) and the auxiliary chamber (12), and a flow limiting hole is provided on the flow limiting plate. The flow limiting hole is used to limit the flow of gas from the auxiliary chamber (12) to the main chamber (11) and form a pressure gradient. Through the synergistic effect of the bypass branch and the current limiting plate, dynamic pressure balance can be achieved between the high pressure of the secondary chamber and the low pressure of the main chamber, so as to support two working modes: etching first and then stripping, and etching while stripping.

2. The dual-stage pressure-regulated plasma etching and cleaning equipment according to claim 1, characterized in that: A pneumatic valve (4) is also provided in the bypass branch, and the pneumatic valve (4) is connected in parallel with the pressure regulating valve (3); The pneumatic valve (4) can assist in rapid pressure relief.

3. The dual-stage pressure-regulated plasma etching and cleaning equipment according to claim 1, characterized in that: The opening of the second valve plate (22) is linked to the opening of the pressure regulating valve (3). When the first valve plate (21) is opened, the opening θ of the second valve plate (22) satisfies: θ=k·(P2-P1) / Q P ; Wherein, P1 is the target pressure of the main chamber (11), P2 is the measured pressure of the secondary chamber (12), Q P is the calibrated pumping speed of the vacuum pump, k is the conductance compensation coefficient, and k is calibrated through simulation experiments.

4. The dual-stage pressure-regulated plasma etching and cleaning equipment according to claim 1, characterized in that: The aperture Φ of the flow-limiting hole satisfies: ； Wherein, Q is the inlet flow rate of the remote plasma source (1), and ρ is the density of the process gas for debonding.

5. The dual-stage pressure-regulated plasma etching and cleaning equipment according to claim 4, characterized in that: The aperture of the flow-limiting hole is adjustable; The flow limiting plate is rotatably arranged at the outlet of the sub-chamber (12), and at least two flow limiting holes with different apertures are formed on the flow limiting plate. The flow limiting plate is rotated so that the flow limiting holes with different apertures face the outlet of the sub-chamber (12), so as to achieve a dynamic balance between different gas flow rates and intra-chamber pressures; A needle valve is also provided at the outlet of the sub-chamber (12), and the needle tip of the needle valve can be inserted into the flow-limiting hole facing the outlet of the sub-chamber (12). The cone angle of the needle tip is 55°-65°, and the degree of opening of the flow-limiting hole can be changed by controlling the insertion degree of the needle tip.

6. The dual-stage pressure-regulated plasma etching and cleaning equipment according to claim 1, characterized in that: It also includes a filter, which is installed at the output end of the radio frequency power supply and the remote plasma source (1) and is used to eliminate frequency band interference between the radio frequency source and the microwave source.

7. The dual-stage pressure-regulated plasma etching and cleaning equipment according to claim 1, characterized in that: A bent air pipe (31) is provided in the sub-chamber (12), one end of the bent air pipe (31) is connected to the side extraction branch, and the other end faces the cavity wall or bottom wall of the sub-chamber (12), and the other end of the bent air pipe (31) serves as the inlet of the side extraction branch and is arranged away from the remote plasma source (1); At least two levels of baffles (32) are further provided in the sub-chamber (12), and the at least two levels of baffles (32) are nested and arranged, and an opening is provided on any baffle (32), and the openings on any two adjacent baffles (32) are away from each other; The outlet of the secondary chamber (12) communicating with the main chamber (11) is located within the innermost first-level baffle (32); The other end of the bent air pipe (31) is arranged between the outermost first-level baffle (32) and the cavity wall of the secondary chamber (12); The bent air pipe (31) and the baffle (32) cooperate to prevent active free radicals from entering the bypass branch.

8. The dual-stage pressure-regulated plasma etching and cleaning equipment according to claim 1, characterized in that: The sub-chamber (12) is arranged in a trumpet shape, and the further away from the remote plasma source (1), the larger the inner diameter of the sub-chamber (12); When the active free radicals flow toward the outlet of the sub-chamber (12), the flow rate gradually decreases, which can increase the residence time of the active free radicals in the sub-chamber (12) and is also conducive to the active free radicals being more evenly distributed around the outlet of the sub-chamber (12) when the first valve plate (21) is closed; A concave curved surface is provided on one side of the first valve plate (21) close to the secondary chamber (12); when the first valve plate (21) is opened, the concave curved surface can guide the airflow to rush toward the main chamber (11), thereby reducing the diffusion loss of active free radicals.

9. The dual-stage pressure-regulated plasma etching and cleaning equipment according to any one of claims 1 to 8, characterized in that: The etching and stripping working mode includes a repeated cycle, the duration of any of the cycles is T, and any of the cycles includes an etching period and a cleaning period, the duration of the etching period is T1, the duration of the cleaning period is T2, and T1:T2≥85%:15%; During the etching period, the etching process gas is continuously introduced into the main chamber (11), the first valve plate (21) is closed, the remote plasma source (1) is operated, and the pre-generated active free radicals are temporarily stored in the sub-chamber (12); During the cleaning period, the etching gas is stopped from being supplied, the first valve plate (21) is opened, and active free radicals enter the main chamber (11), thereby cleaning by-products and increasing the etching rate.

10. A wafer processing method, implemented by using the dual-stage pressure-regulated plasma etching and cleaning equipment according to any one of claims 1 to 8, characterized in that: The wafer is a polysilicon gate or polysilicon-based structure; The wafer processing method comprises the following steps: Etching the wafer in a main chamber (11), introducing a mixed gas containing HBr and NF3, or containing SF6 and C4F8, as an etching process gas into the main chamber (11), to generate a by-product containing silicon halide or a fluorocarbon polymer; The proportion of halogen atoms in the etching process gas is not less than 50%; A mixed gas containing O2 and H2O, or containing NF3 and O2, is introduced into a remote plasma source (1) as a process gas for debonding to excite the plasma and generate active free radicals; The volume proportion of oxygen-containing components in the process gas used for degumming is not less than 40%; After etching is completed, active free radicals enter the main chamber (11), thereby removing the adhesive from the wafer surface and decomposing the etching residues. The etching residues are converted into at least one of the gaseous substances SiO2, SiF2O, COF2, and HF and are pumped away by the vacuum pump (2).

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