Ion etching device for PVD (Physical Vapor Deposition) coating equipment

Abstract

The invention discloses an ion etching device for PVD (Physical Vapor Deposition) coating equipment. The ion etching device comprises an auxiliary anode, a main and standby double-group tungsten filament heating module, an inert gas directional introduction module, a vacuum and electric connection module and a control and protection module. Through the design of the main and standby tungsten filaments and the automatic overlapping switching strategy, it is ensured that when one tungsten filament fails, seamless switching to the standby tungsten filament can be achieved, shutdown caused by filament breakage or degradation is effectively avoided, the service life of the device is prolonged, long-period continuous production is guaranteed, and the operation efficiency and production continuity of the device are greatly improved. Meanwhile, electric arc particle pollution is avoided through hot electron emission, and the surface cleanliness is high; the matching range of pressure, bias pressure and gas is wide, the method is suitable for multiple materials and complex morphology, and the process repeatability is good; the flange and the electric penetration assembly are modularized, and the tungsten filament / anode / gas supply assembly is quickly replaced, so that the maintenance time is shortened, and the maintenance cost is reduced; the whole system is simple in structure, does not need a complex magnetic field and a multi-stage electrode, and is low in equipment manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of physical vapor deposition (PVD) coating equipment technology, specifically to an ion etching apparatus for PVD coating equipment. Background Technology

[0002] In physical vapor deposition (PVD) processes, the cleanliness, activity, and microstructure of the workpiece surface have a decisive impact on the adhesion strength, density, and overall performance of the coating. In the pretreatment stage of PVD coating, ion etching effectively removes contaminants and oxide layers by bombarding the substrate surface with high-energy ions, while simultaneously forming a micro-roughened structure, significantly improving the adhesion strength between the coating and the substrate. Currently, the mainstream ion etching technologies include three routes: arc etching, ion source etching, and thermionic emission etching.

[0003] Among these technologies, arc etching boasts advantages such as high ionization rate and fast etching rate, but its inherent limitations restrict its application. During arc discharge, the unstable migration of the cathode spot generates a large number of micron- and submicron-sized particles. These particles deposit on the substrate surface, severely impacting surface cleanliness and microstructure quality. Furthermore, the fixed installation position of the arc excitation device restricts the spatial distribution flexibility of the plasma field. Combined with the inherent instability of the discharge itself, this leads to a significant decrease in etching uniformity and the emergence of noticeable etching blind zones when processing tools with complex geometries, especially in shielded areas such as deep holes and narrow slits.

[0004] Ion source etching technology can generate highly directional and stable ion beams, avoiding particle contamination problems. However, the system is highly complex, requiring precise magnetic field control and protection modules and multi-stage electrode structures, resulting in high equipment manufacturing costs. Furthermore, the long-term stability of the magnetic field system, the sputtering resistance of the electrode materials, and the matching accuracy of system components all pose challenges to process stability, making its process window relatively narrow and limiting its adaptability to different materials and workpiece shapes.

[0005] Thermionic emission etching (TEE) technology generates thermionic electrons by heating a tungsten filament, maintaining a stable glow discharge in a low-pressure inert gas environment. It boasts advantages such as simple structure, low cost, and strong adaptability, making it a promising technology. However, existing technologies suffer from the following problems: 1) After thermionic electrons are generated, there is a lack of effective trajectory control. Most electrons fly directly to the anode and are collected, resulting in short effective collision paths and a low probability of collision with gas molecules, leading to insufficient ionization efficiency; 2) The electron trajectory lacks regulation, and the mismatch between the electric field and the gas flow field distribution leads to uneven plasma spatial distribution, resulting in edge and shielding effects when processing complex workpieces; 3) Traditional devices use a single tungsten filament design. When the tungsten filament fails due to high-temperature evaporation, thermal stress, or contamination, the process must be interrupted for vacuum replacement, severely impacting production efficiency and equipment reliability. These technical bottlenecks significantly restrict the application of TEE technology in high-end PVD coating fields.

[0006] Therefore, there is an urgent need to develop a new ion etching device for PVD coating equipment. While retaining the advantages of thermionic etching technology, this device should effectively solve key technical problems such as electron utilization efficiency, plasma uniformity and system reliability through innovative system design and control strategies, so as to achieve simultaneous improvement in etching quality and equipment stability. Summary of the Invention

[0007] The purpose of this invention is to provide an ion etching device for PVD coating equipment. This system has the advantages of controllable electron movement, uniform plasma, high reliability and easy maintenance. It can overcome the defects of low electron utilization, uneven plasma distribution and poor system reliability in the prior art, and achieve efficient, low-pollution and repeatable etching of complex tools.

[0008] To achieve the above objectives, the present invention provides the following technical solution: an ion etching apparatus for PVD coating equipment, comprising: (1) Auxiliary anode: The rectangular gradually expanding auxiliary anode cover formed by the four side walls and the front axial straight section are integrally formed. The auxiliary anode is only open on the side facing the rotating frame without an end cap. The opening surface is arranged perpendicular to the horizontal plane. The auxiliary anode is provided with a closed end cap on the side facing away from the rotating frame and is electrically connected to the anode lead-out end. When installed, the opening surface of the auxiliary anode faces the rotating frame and maintains a direct line of sight between it and the workpiece frame. It does not block the path of ions accelerating from the near-field of the tungsten wire to the workpiece of the rotating frame, so as to provide a direct line of sight for ions. To smooth the electric field at the opening edge and suppress local field enhancement, an axial straight section is integrally extended coaxially with the expanding section on the opening side of the auxiliary anode cover. This straight section is a short rectangular tube with parallel sidewalls, its inner cross-sectional dimension is not smaller than the outer cross-sectional dimension of the cover, its length is limited, and it does not form an obstruction. Both the sidewalls and the straight section are continuous conductive solid surfaces, applying a single adjustable positive potential to the entire structure.

[0009] (2) Main and backup dual-group tungsten wire heating module: includes a main tungsten wire group and a backup tungsten wire group, as well as corresponding clamping components and power supply, and each of the main tungsten wire group and the backup tungsten wire group includes two tungsten wires, and the clamping components are fixedly installed on the inner side of the auxiliary anode; Specifically, Group A tungsten filament heating units are set up as the main units for conventional thermionic emission, consisting of a first tungsten filament and its corresponding first and third clamping components, a second tungsten filament and its corresponding second and fourth clamping components, and power supplies 1 and 2; Group B tungsten filament heating units are set up as online backup, consisting of a third tungsten filament and its corresponding fifth and seventh clamping components, a fourth tungsten filament and its corresponding sixth and eighth clamping components, and power supplies 3 and 4. The control and protection module monitors the emission / plasma current and cavity operating conditions in real time, and automatically and seamlessly switches to Group B when Group A is abnormal, ensuring continuous operation. (3) Inert gas directional introduction module: Inert gas is directionally injected into the near-field of tungsten wire through mass flow controller and gas introduction component, with nozzle facing the gap area between tungsten wire and auxiliary anode, forming a local high ionization zone and increasing the probability of electron-gas collision; (4) Vacuum and electrical connection module: includes a vacuum flange and a vacuum through electrode. The vacuum flange is connected to the etching device and is arranged in parallel with the auxiliary anode to achieve sealed installation with the PVD cavity. The vacuum through electrode is inserted into the side wall of the vacuum flange to provide a reliable electrical connection between the tungsten wire and the external power supply under high vacuum. (5) Control and protection module: It is electrically connected to each power supply and mass flow controller. Specifically, it is electrically connected to the tungsten filament heating power supply, anode power supply, mass flow controller and workpiece bias power supply. It has ramp heating / cooling, ramp voltage increase / decrease, threshold criterion, overvoltage / overcurrent / overtemperature / undervoltage protection and interlocking, and realizes orderly management of ignition, steady state, abnormal switching and shutdown.

[0010] Preferably, in the main and backup dual-group tungsten filament heating module, the control and protection module monitors the emission current and plasma current in real time, and automatically switches to the backup tungsten filament group when the main tungsten filament group is abnormal.

[0011] Preferably, the tungsten wire has a diameter of 0.5–1.2 mm, an effective length of 200–500 mm, a distance of 20–50 mm between the tungsten wire and the auxiliary anode, an operating temperature of 2200–2600 K, and an operating current of 30–80 A.

[0012] Preferably, the throat of the auxiliary anode is located near the tungsten wire side, is rectangular, and has dimensions of 800-1200mm in length × 80-120mm in width. The outer opening is proportionally enlarged to the throat opening, with an area ratio of 1.2-2.5, and the corners are rounded to R1-R8mm. The opening surface is arranged perpendicular to the horizontal plane and faces the rotating frame.

[0013] Preferably, the expanding section (sloping wall) of the auxiliary anode transitions from the throat to the outer opening of the cover, with an effective axial length of 10-60mm, a expanding angle of 5°-25°, and a corner radius of R1-R8mm; ensuring that the ion direct channel is not blocked; the axial straight section (equal cross-section) is coaxial with the expanding section, with a length of 5-25mm (preferably 8-15mm), and the window size inside the straight section is 1.00-1.10 times the size of the outer opening of the cover to avoid blocking the effective opening, with an outer lip chamfer or radius of R1-R5mm, and does not intrude into the effective opening, thereby ensuring that the ion direct channel is unobstructed.

[0014] Preferably, the inert gas is a mixture of Ar as the main component and Kr / Xe volume fraction ≤30%, used to enhance ionization in the deep cavity region; the total flow rate is 50-300 sccm, and the working chamber pressure is 0.5-3.0 Pa; the nozzle diameter of the gas introduction component is 1-3 mm, the distance from the tungsten wire is 30-80 mm, and it points towards the tungsten wire-auxiliary anode gap.

[0015] The present invention also provides an ion etching process for PVD coating equipment, comprising the following steps: Pre-extraction and baking: Extract the cavity to 1×10 -1 ~1×10 -3 Pa, heating the workpiece and fixture to 400-550℃ and maintaining the temperature to remove adsorbed and volatile substances; Ignition and plasma establishment: Introduce inert gas to achieve a pressure of 0.1-10 Pa (preferably 0.5-3 Pa), apply a small positive potential of 0-100 V (preferably 50-80 V) to the auxiliary anode, and ramp up the tungsten filament current to 30-80 A to establish a stable glow discharge; Bias etching: Apply a negative bias voltage (DC or pulsed DC) with a typical voltage amplitude of -200 to -1000V to the workpiece and etch for 10-60 minutes (preferably 15-45 minutes); use the workpiece bias current or plasma current as the main control variable, and finely adjust the auxiliary anode potential and near-field gas flow rate to maintain the target etching power density. Termination and Cooling: Reduce power in reverse order of workpiece bias voltage → auxiliary anode potential → tungsten wire current, and stop gas supply. After the cavity pressure and temperature stabilize, proceed to the subsequent coating process.

[0016] Preferably, in the bias etching step, the workpiece bias current or plasma current is used as the main control variable, and the auxiliary anode potential and inert gas flow rate are finely adjusted in conjunction.

[0017] Preferably, the bias etching uses a pulsed DC bias with a frequency of 10-150kHz and a duty cycle of 20%-80%.

[0018] Preferably, during the process, the workpiece rotates or planetarily rotates at a speed of 1-5 rpm, and the etching uniformity is improved by optimizing the installation spacing / attitude, matching the throat size and the involute angle of the auxiliary anode, optimizing the length of the axial straight section and the window size, and distributing the direction and flow of the inert gas.

[0019] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, through a dual-set tungsten filament design with primary and backup and an automatic overlapping switching strategy, ensures seamless switching to the backup set when one set of tungsten filaments fails, effectively avoiding downtime caused by filament breakage or degradation, extending the life of the equipment, ensuring long-cycle continuous production, and significantly improving the operating efficiency and production continuity of the equipment.

[0020] 2. This invention utilizes a unique rectangular gradually expanding auxiliary anode cover and a closed end cap. The gradually expanding section constructs a potential well, extending the effective electron path and forcing hot electrons to undergo helical or reciprocating motion within it. This significantly lengthens the effective electron path and dramatically improves the collisional ionization efficiency between electrons and gas molecules, thereby forming a stable, high-density plasma region around the tungsten filament. Meanwhile, the straight axial section at the front end smooths the electric field at the opening edge, reducing hot spots and micro-discharges. Combined with geometric and installation optimizations, this improves the uniformity of complex workpieces while ensuring that the ion direct channel is not obstructed, thus playing a role in plasma extraction and ion beam shaping. This allows ions to bombard the workpiece more uniformly and directionally through the line-of-sight channel, making it particularly suitable for the uniform processing of large-area workpieces.

[0021] 3. This invention uses thermionic emission to avoid arc particle contamination, resulting in high surface cleanliness; at the same time, it has a wide range of pressure, bias and gas ratio, adapting to multiple materials and complex morphologies, and has good process repeatability; while modular flanges and electrical penetration components, quick-change tungsten wire / anode / gas supply components shorten maintenance time and reduce maintenance costs; the overall system structure is simple, requiring no complex magnetic field and multi-stage electrodes, resulting in low equipment manufacturing costs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the ion etching apparatus in an embodiment of the present invention; Figure 2 This is a schematic diagram comparing the adhesion of AlTiN coatings in Example 1 and Comparative Example 1 of the present invention.

[0023] Legend: 1. Tungsten wire; 101. First tungsten wire; 102. Second tungsten wire; 103. Third tungsten wire; 104. Fourth tungsten wire; 2. Clamping components; 201. First clamping component; 202. Second clamping component; 203. Third clamping component; 204. Fourth clamping component; 205. Fifth clamping component; 206. Sixth clamping component; 207. Seventh clamping component; 208. Eighth clamping component; 3. Gas introduction assembly; 4. Auxiliary anode; 5. Vacuum flange; 6. Vacuum through electrode. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1 Please see Figure 1 The present invention provides an ion etching device for PVD coating equipment, including a tungsten filament heating main and backup dual-group module, an inert gas directional introduction module, an auxiliary anode 4, a vacuum and electrical connection module, and a control and protection module.

[0026] In the dual-group module for tungsten filament heating, group A tungsten filament heating unit is set as the main unit. Group A tungsten filament heating unit consists of two parallel wires: the first tungsten filament 101 and its corresponding first clamping component 201 and third clamping component 203, the second tungsten filament 102 and its corresponding second clamping component 202 and fourth clamping component 204, and power supplies (not shown) 1 and 2. Set up a group B tungsten wire heating unit as an online backup. The group B tungsten wire heating unit consists of two parallel wires: the third tungsten wire 103 and its corresponding fifth clamping component 205 and seventh clamping component 207, the fourth tungsten wire 104 and its corresponding sixth clamping component 206 and eighth clamping component 208, and power supplies (not shown) 3 and 4.

[0027] The control and protection module monitors the emission / plasma current and cavity operating conditions in real time, automatically and seamlessly switching to group B when group A malfunctions. The inert gas directional introduction module injects Ar into the near-field of the tungsten filament via a mass flow controller and gas introduction component 3, with the nozzle facing the gap between the tungsten filament and the auxiliary anode. The auxiliary anode 4 is an integrated anode consisting of a rectangular expanding cover and a front axial straight section. The vacuum and electrical connection module includes a vacuum flange 5 and a vacuum through-electrode 6. The control and protection module is electrically connected to each power supply and controller for orderly management. The tungsten filament diameter is 0.8–mm, with an effective single-filament length of 500–mm; the tungsten filament-anode spacing is 30–mm; and the auxiliary anode opening rate is 50%.

[0028] Etching process: cavity drawn down to 1×10 -2 Pa, after the workpiece is heated to 500°C, Ar is introduced to make the pressure 1Pa, an 80V positive potential is applied to the auxiliary anode, and the tungsten wire current is ramped up to 50A; a -500V pulsed DC bias voltage is applied to the workpiece, with a frequency of 50kHz and a duty cycle of 50%, and etching is performed for 30min; the workpiece is rotated 3rpm, and segmented anode potential and multi-point gas supply compensation are applied; after etching is completed, the power is reduced in reverse order and the gas supply is stopped.

[0029] Example 2 An ion etching apparatus for PVD coating equipment has the same structure as in Example 1, but the process parameters are adjusted as follows: the cavity is evacuated to 5×10⁻⁶. -2 Pa, after the workpiece is heated to 350°C, Ar is introduced to make the pressure 2Pa, a 30V positive potential is applied to the auxiliary anode, and the tungsten wire current is ramped up to 40A; a -800V DC bias voltage is applied to the workpiece, and etching is performed for 45 minutes; the workpiece is rotated 2 rpm, and segmented anode potential and multi-point gas supply compensation are applied; after etching is completed, the power is reduced in reverse order and the gas supply is stopped.

[0030] Example 3 An ion etching apparatus for PVD coating equipment has the same structure as in Example 1, but the process parameters are adjusted as follows: the cavity is reduced to 1×10⁻⁶. -3 After heating the workpiece to 400°C, a mixture of Ar and Kr gas is introduced to bring the pressure to 0.5Pa. A positive potential of 100V is applied to the auxiliary anode, and the tungsten wire current is ramped up to 35A. A pulsed DC bias of -1000V is applied to the workpiece at a frequency of 100kHz and a duty cycle of 70%, and etching is performed for 20 minutes. The workpiece is rotated at 5 rpm, and segmented anode potential and multi-point gas supply compensation are applied. After etching is completed, the power is reduced in reverse order, and the gas supply is stopped.

[0031] Example 4 An ion etching apparatus for PVD coating equipment has the same structure as in Example 1, but the process parameters are adjusted as follows: the cavity is reduced to 1×10⁻⁶. -1Pa, after the workpiece is heated to 250°C, Ar is introduced to make the pressure 3Pa, a 50V positive potential is applied to the auxiliary anode, and the tungsten wire current is ramped up to 80A; a -300V pulsed DC bias voltage is applied to the workpiece, with a frequency of 20kHz and a duty cycle of 30%, and etching is performed for 60min; the workpiece is rotated 1rpm, and segmented anode potential and multi-point gas supply compensation are applied; after etching is completed, the power is reduced in reverse order and the gas supply is stopped.

[0032] Comparative Example 1 An ion etching apparatus for PVD coating equipment has the same structure as in Example 1, but without an auxiliary anode module. The etching process is exactly the same as in Example 1, including pre-evacuation and baking, ignition and plasma establishment, bias etching, uniformity control, and termination and cooling steps. Due to the lack of potential control by the auxiliary anode, the hot electron trajectory is not effectively extended, resulting in lower ionization efficiency, decreased plasma spatial distribution uniformity, and poor etching effect.

[0033] Working principle: During operation, the tungsten filaments of the main tungsten filament assembly are heated to the thermionic emission temperature (preferably 2200-2600K) and emit thermionic electrons. Under the potential well formed by the rectangular expanding cover and the end cap, the electrons cannot fly directly to the anode, but instead travel back and forth between the tungsten filaments and the side wall of the cover multiple times. The trajectory changes from a straight line to a spiral or reciprocating motion, which significantly prolongs the effective collision path with the inert gas. At the same time, the electrons collide frequently with the directional Ar gas molecules, generating efficient avalanche ionization and forming a stable high-density plasma region around the tungsten filaments. During this process, the integrated axial straight section on the opening side smooths the equipotential surface at the opening edge under a single anode potential, reduces local field spikes, and provides short-range electric field shaping and plasma outflow buffer. At the same time, because its inner cross section is not smaller than the outer opening of the cover and its length is limited, it maintains a direct line of sight to the rotating frame and does not form geometric obstruction for ion acceleration.

[0034] A negative bias voltage (DC or pulsed DC) is applied to the workpiece, and inert gas ions are accelerated along the direct line-of-sight channel to bombard the workpiece surface with a set kinetic energy, removing contaminants and oxide layers, while simultaneously achieving surface activation and micro-roughening, completing the etching process and providing an ideal interface for subsequent coatings. The entire process is monitored in real time and the parameters are optimized through closed-loop control, and the system automatically switches to the backup group in case of an anomaly in the main tungsten filament group, maintaining continuous and stable process operation.

[0035] Result evaluation: Observation using a scanning electron microscope (SEM), such as Figure 2 As shown, after processing with this process, the AlTiN coatings prepared by the same deposition process after etching according to the method described in Example 1 and Comparative Example 1 show that the AlTiN coating etched using the device described in Example 1 has a significantly better adhesion than that of Comparative Example 1.

[0036] In summary, this invention addresses the low electron utilization rate and poor plasma inhomogeneity and continuity issues inherent in thermionic emission etching (TEE) by proposing an integrated solution: "gradually expanding auxiliary anode + coaxial axial straight section + near-field directional gas supply + primary / backup tungsten filament design + closed-loop control." By introducing an auxiliary anode near the tungsten filament for potential regulation and directional gas supply, combined with primary / backup redundancy and closed-loop control strategies, this solution addresses three key challenges—electron utilization rate, plasma uniformity, and system reliability—while retaining the advantages of TEE. This achieves the goal of efficient, low-pollution, and repeatable etching of complex tools and workpieces, and is suitable for pre-coating ion etching cleaning and activation of tools and complex workpieces made of cemented carbide, mold steel, high-speed steel, and ceramics.

[0037] Specifically, this invention integrates a rectangular, gradually expanding anode with an axially straight section on the opening side, creating both an electron potential trap and a smooth electric field at the opening. The straight section window is no smaller than the outer opening, ensuring unobstructed ion access. Inert gas is directionally injected into the tungsten wire-anode gap, significantly extending the effective electron collision path and improving ionization rate. Workpiece bias voltage / plasma current are used as the main control variables to link the anode potential and near-field flow rate, achieving high-density plasma and controllable uniformity. Real-time monitoring and automatic seamless switching between the main and backup tungsten wires ensure continuous production without downtime. This solution, with its simple structure and controllable cost, significantly improves etching consistency in shielded areas such as deep holes and narrow slits and expands the process window, making it suitable for pre-coating cleaning and activation of complex tools and irregularly shaped workpieces.

[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ion etching device for a PVD coating plant, characterized in that It comprises: auxiliary anode (4): the rectangular gradually expanding auxiliary anode cover body composed of four side walls and the front end axial straight section are integrally formed, the auxiliary anode (4) is provided with a closed end cover on the side away from the trolley and is electrically connected with the anode lead-out end, and the opening surface of the auxiliary anode (4) faces the trolley and provides a direct line of sight channel for ions; main and standby double tungsten wire heating modules: containing a main tungsten wire group and a standby tungsten wire group, and corresponding clamping components (2) and power supplies, and the main tungsten wire group and the standby tungsten wire group each contain two tungsten wires (1), and the clamping components (2) are fixedly installed on the inner side of the auxiliary anode (4); inert gas directional introduction module: inert gas is introduced into the gap between the tungsten wire (1) and the auxiliary anode (4) through a mass flow controller and a gas introduction assembly (3); vacuum and electrical connection module: containing a vacuum flange (5) and a vacuum through electrode (6), the vacuum through electrode (6) is inserted through the side wall of the vacuum flange (11), and the vacuum flange (11) is arranged in parallel with the auxiliary anode (4); control and protection module: electrically connected with each power supply and mass flow controller.

2. The ion etching device for a PVD coating installation according to claim 1, characterized in that In the main and standby double tungsten wire heating module, the control and protection module monitors the emission current and plasma current in real time, and automatically switches to the standby tungsten wire group when the main tungsten wire group is abnormal.

3. The ion etching device for a PVD coating installation according to claim 1, characterized in that The tungsten wire (1) has a diameter of 0.5-1.2mm, an effective length of single wire of 200-500mm, a distance between the tungsten wire (1) and the auxiliary anode (4) of 20-50mm, a working temperature of 2200-2600K, and a working current of 30-80A.

4. The ion etching device for a PVD coating installation according to claim 1, characterized in that The throat size of the auxiliary anode (4) is 800-1200mm in length and 80-120mm in width, the outer opening and the throat are enlarged at the same ratio, the area ratio is 1.2-2.5, and the corner radius R1-R8mm; the opening surface is perpendicular to the horizontal plane and faces the trolley.

5. The ion etching device for a PVD coating installation according to claim 1, characterized in that The auxiliary anode (4) has an axial effective length of the gradually expanding section of 10-60mm and a gradually expanding angle of 5°-25°; the axial straight section has a length of 5-25mm, the window size in the straight section is 1.00-1.10 times the size of the outer opening of the cover body, the outer lip has a chamfer or a round corner R1-R5mm, and does not invade the effective opening.

6. The ion etching device for a PVD coating installation according to claim 1, characterized in that The inert gas is a mixture of Ar as the main component and Kr / Xe with a volume fraction of ≤30%; the total flow is 50-300sccm, the working cavity pressure is 0.5-3.0Pa; the gas introduction assembly (3) has a nozzle diameter of 1-3mm, a distance of 30-80mm from the tungsten wire (1) and is directed to the gap between the tungsten wire (1) and the auxiliary anode (4).

7. An ion etching process for a PVD coating installation, using an ion etching device for a PVD coating installation according to any one of claims 1 to 6, characterized in that It comprises the following steps: Pre-pumping and baking: Pump the chamber to 1 x 10 -1 ~ 1 x 10 -3 Pa and heat the workpiece and fixture to 400-550°C; ignition and plasma establishment: introducing inert gas to make the pressure reach 0.1-10Pa, applying a positive potential of 0-100V to the auxiliary anode (4), and increasing the tungsten wire (1) current to 30-80A; bias etching: applying a negative bias of -200 to -1000V to the workpiece for etching for 10-60 minutes; termination and cooling: reducing the power in the reverse order of the workpiece bias→auxiliary anode potential→tungsten wire current, and stopping the gas supply.

8. Ion etching process for PVD coating devices according to claim 7, characterized in that, In the bias etching step, the workpiece bias current or plasma current is used as the main control quantity to link and fine-tune the auxiliary anode (4) potential and the inert gas flow.

9. Ion etching process for PVD coating devices according to claim 7, characterized in that, The bias etching adopts a pulse DC bias with a frequency of 10-150 kHz and a duty cycle of 20%-80%.

10. The ion etching process for a PVD coating installation according to claim 7, characterized in that, In the process, the workpiece rotates at a speed of 1-5 rpm, and through the matching of the throat size and the taper angle of the auxiliary anode (4), the optimization of the axial straight section length and the window size, and the direction and flow distribution of the directional introduction of the inert gas, the directional compensation of the shielded area of deep holes, narrow slits and sharp corners is realized to improve the etching uniformity.

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