Precision adjustable plasma etching apparatus and adjustment method for electrode gap

Abstract

This invention discloses a plasma etching apparatus and adjustment method with precisely adjustable electrode gap. The etching apparatus includes a vacuum chamber, within which are arranged an upper electrode assembly, a lower electrode assembly, a gantry, a lead screw assembly, and distance sensors. The distance sensors are grouped on the upper electrode assembly, the lower electrode assembly is fixed to the bottom of the vacuum chamber, and the upper electrode assembly is fixedly connected to the gantry. Both ends of the gantry are connected to the lead screw assembly. The etching apparatus of this invention can precisely adjust the gap and angle between the upper electrode and the workpiece, promoting uniform plasma distribution and improving the uniformity and consistency of processing. Simultaneously, a cooling system is included to effectively control temperature fluctuations within the etching apparatus. The adjustment method of this invention can continuously and precisely adjust the distance between the upper electrode nozzle and the workpiece during the etching process, maintaining a constant processing distance between the upper electrode nozzle and the workpiece, providing more efficient and stable processing capabilities.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and more specifically to a plasma etching apparatus and adjustment method with precisely adjustable electrode gap. Background Technology

[0002] In the semiconductor manufacturing field, capacitively coupled plasma (CCP) etching equipment is widely used in key processes such as etching, thin film deposition, and sputtering due to its ability to generate large-area plasma. The working principle of plasma etching equipment is based on capacitive coupling, utilizing the principle of parallel-plate capacitors to continuously generate plasma. An radio frequency (RF) power supply is applied to the two electrodes of the parallel plates, and process gas enters the reaction chamber, generating plasma under the excitation of the RF power supply. Charged particles, under the influence of the electric field, continuously bombard the workpiece surface, thereby removing material and achieving the etching purpose. With the continuous miniaturization and performance improvement of semiconductor devices, the performance requirements for plasma etching equipment are also increasing.

[0003] However, existing plasma etching equipment suffers from several unresolved issues that limit its efficiency and quality in semiconductor manufacturing processes. Non-uniformity in plasma density can lead to asymmetry in etching rates or the azimuth of critical dimensions, thus affecting etching performance and yield. To improve plasma uniformity, researchers have explored various methods, including magnetic shielding to correct non-uniformity induced by the Earth's magnetic field and adjusting electrode gap techniques to achieve uniform ion flux across the silicon wafer surface.

[0004] In plasma etching equipment, the distance between electrode plates directly determines the range of electron movement and collision frequency in the high-frequency electric field. When the electrode plate gap increases, the electron path lengthens, potentially reducing the number of collisions and thus lowering the plasma density. Conversely, when the electrode plate gap decreases, the electron collision frequency increases, contributing to the generation of higher-density plasma. Furthermore, adjusting the electrode plate gap can affect the uniformity of plasma distribution, ensuring the consistency and accuracy of the etching process. However, existing plasma etching equipment suffers from low precision in electrode plate adjustment, resulting in lower surface uniformity and consistency after workpiece processing. During processing, the continuous removal of material from the workpiece surface increases the distance between the workpiece and the upper electrode plate, affecting etching efficiency and effectiveness. Additionally, the vacuum processing environment hinders timely heat dissipation, leading to localized overheating and poor processing stability. This not only affects the uniformity of workpiece processing but may also shorten the equipment's lifespan. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a plasma etching apparatus and adjustment method with precisely adjustable electrode gap. The plasma etching apparatus of this invention can precisely adjust the gap between the upper electrode plate and the workpiece, ensuring parallelism between them, maintaining a constant processing distance, promoting uniform plasma distribution on the workpiece surface, providing more efficient and stable processing capabilities, and further improving the uniformity and consistency of processing to meet the needs of high-precision semiconductor processing. The etching apparatus of this invention also includes a cooling system, which can effectively control temperature fluctuations within the etching apparatus, making the working environment more stable, ensuring processing quality, preventing damage due to localized overheating, and extending the lifespan of the apparatus. Furthermore, this invention provides a method for precisely adjusting the electrode gap, which allows for continuous and precise adjustment of the distance between the upper electrode nozzle and the workpiece during the etching process, maintaining a constant processing distance and providing more efficient and stable processing capabilities.

[0006] The technical solution of the present invention for plasma etching apparatus is as follows:

[0007] A plasma etching apparatus with precisely adjustable electrode gap includes a vacuum chamber. The vacuum chamber houses an upper electrode assembly, a lower electrode assembly, a gantry, a lead screw assembly, and distance sensors. The distance sensors are grouped on the upper electrode assembly. The lower electrode assembly is fixed to the bottom of the vacuum chamber. The upper electrode assembly is fixedly connected to the gantry. Both ends of the gantry are connected to corresponding lead screw assemblies, enabling adjustment of the distance and angle between the upper electrode assembly and the workpiece. A process gas inlet pipe and a process gas outlet pipe are inserted into the shell of the vacuum chamber. The upper electrode assembly includes an upper insulating ring, a gas distributor, and an upper electrode gas spray nozzle. The gas distributor is connected to the process gas inlet pipe and is fixedly connected to the gantry frame via an upper insulating ring. The lower end of the gas distributor is connected to the upper electrode gas nozzle. The process gas inlet pipe transports the process gas to the gas distributor for uniform distribution, and then it is injected through the upper electrode gas nozzle into the gap between the upper electrode assembly and the lower electrode assembly. The lower electrode assembly includes a lower electrode worktable and a rotary motor. The stator of the rotary motor is fixedly connected to the bottom of the vacuum chamber, and the rotor of the rotary motor is connected to the lower electrode worktable. The lower electrode worktable is equipped with a temperature sensor and a cooling system.

[0008] Compared with the prior art, the plasma etching apparatus with precisely adjustable electrode gap of the present invention has achieved significant progress, as detailed below:

[0009] 1) Good processing effect. The etching device of the present invention adjusts the distance between the upper electrode gas nozzle and the workpiece through the screw rod assembly. During the etching process, the distance between the upper electrode gas nozzle and the workpiece is maintained, providing more efficient and stable processing capabilities to meet the requirements of high-precision semiconductor processing. In addition, a rotating motor is added to the bottom of the lower electrode workbench of the etching device of the present invention, which can drive the workpiece to rotate synchronously and uniformly during the processing, promoting the uniform distribution of plasma in the processing area, and further improving the uniformity and consistency of the processing.

[0010] 2) High stability. The etching device of the present invention sets a cooling system on the lower electrode workbench to improve the thermal management performance, ensuring that during the long-term processing, the temperature is maintained at a safe and stable level, making the working environment more stable, guaranteeing the processing quality of the surface of the workpiece, ensuring the uniformity of the workpiece etching, and at the same time, preventing local overheating of the device from causing damage and extending the service life of the device.

[0011] Further, in the above plasma etching device with precisely adjustable electrode gap, the distance sensors are evenly arranged along the circumferential direction of the upper electrode gas nozzle, and the number can be 3 - 10.

[0012] Further, in the above plasma etching device with precisely adjustable electrode gap, the cooling system includes a cooling pipe, a coolant inlet, and a coolant outlet. The cooling pipe is arranged inside the lower electrode workbench, and the coolant inlet and the coolant outlet are arranged at both ends of the lower electrode workbench. The cooling pipe is respectively connected to the coolant storage tank through the coolant inlet and the coolant outlet. A cooling pump is arranged between the coolant storage tank and the coolant inlet, and the cooling pump can pump the cooling water from the coolant storage tank into the cooling pipe, exchange heat with the lower electrode workbench, and then flow back into the coolant storage tank. Still further, the cooling pipe is distributed in a "zigzag" shape inside the lower electrode workbench. The "zigzag" distribution increases the contact area between the cooling pipe and the lower electrode workbench, thereby improving the cooling efficiency.

[0013] Further, in the above plasma etching device with precisely adjustable electrode gap, the screw rod assembly includes a screw rod frame and an adjustment slider. Two adjustment motors are arranged on the screw rod frame, and the output ends of the adjustment motors are connected with screw rods. The adjustment slider is simultaneously in clearance fit with the two screw rods to form a transmission connection, and the gantry is fixedly connected to the adjustment slider, so that the position of the gantry can be adjusted by the adjustment motor.

[0014] Furthermore, in the aforementioned plasma etching apparatus with precisely adjustable electrode gap, the upper electrode gas nozzle is made of high-purity aluminum. High-purity aluminum has excellent electrical conductivity; using it as the material for the upper electrode nozzle enhances the nozzle's surface adsorption capacity for process gases, thereby improving discharge efficiency. Moreover, the surface of the upper electrode gas nozzle undergoes a roughening treatment. This roughening treatment involves creating microstructures on the surface of the upper electrode nozzle, which increases the nozzle's surface area and improves plasma generation efficiency.

[0015] Furthermore, in the aforementioned plasma etching apparatus with precisely adjustable electrode gap, the gas distributor and the upper electrode gas nozzle are interconnected via threads. Using threads to connect the gas distributor and the upper electrode gas nozzle is easy to implement.

[0016] Regarding the adjustment method, the technical solution of the present invention is as follows:

[0017] A method for precisely adjusting the electrode spacing of a plasma etching apparatus, the method being used to adjust the electrode spacing of the aforementioned plasma etching apparatus, the process of which is as follows:

[0018] Before processing begins, the motor controls the position of the slider based on the detection data from the distance sensor, adjusting the distance between the upper electrode gas nozzle and the workpiece to the set value. At the same time, the upper electrode gas nozzle and the workpiece are adjusted to be parallel for initial positioning.

[0019] During processing, the total thickness of the workpiece decreases, the distance between the gas nozzle and the workpiece increases, the distance sensor detects a deviation between the distance and the set value, and the adjusting motor will make a slight adjustment to compensate for the deviation.

[0020] Compared with the prior art, the adjustment method of the present invention uses the above-mentioned plasma etching device with precise adjustable electrode gap for adjustment, which can continuously and precisely adjust the distance between the upper electrode nozzle and the workpiece during the etching process, keep the processing distance between the upper electrode nozzle and the workpiece constant, and provide more efficient and more stable processing capabilities. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the plasma etching apparatus with precisely adjustable electrode gap of the present invention;

[0022] Figure 2 This is a schematic diagram of the upper electrode gas nozzle in the plasma etching apparatus with precisely adjustable electrode gap of the present invention.

[0023] Figure 3 This is a schematic diagram of the lower electrode assembly in the plasma etching apparatus with precisely adjustable electrode gap of the present invention.

[0024] Figure 4 This is a schematic diagram of the lead screw assembly in the plasma etching apparatus with precisely adjustable electrode gap of the present invention;

[0025] Figure 5 This is a schematic diagram of the cooling system in the plasma etching apparatus with precisely adjustable electrode gap of the present invention.

[0026] The labels in the attached diagram are as follows: 1-Vacuum chamber; 2-Upper electrode assembly; 201-Upper insulating ring; 202-Gas distributor; 203-Upper electrode gas nozzle; 3-Lower electrode assembly; 301-Lower electrode worktable; 302-Rotary motor; 4-Gantry frame; 5-Screw assembly; 501-Screw support; 502-Adjusting motor; 503-Adjusting slider; 504-Screw; 6-Distance sensor; 7-Cooling system; 701-Cooling pipe; 702-Coolant inlet; 703-Coolant outlet; 8-Coolant storage tank; 9-Cooling pump; 10-Workpiece; 11-Process gas inlet pipe; 12-Process gas outlet pipe. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments, but these descriptions are not intended to be construed as providing a basis for the invention. Contents not described in detail in the following embodiments are all common knowledge in the art.

[0028] Example (see) Figure 1-5 ):

[0029] A plasma etching apparatus with precisely adjustable electrode gap includes a vacuum chamber 1; the vacuum chamber 1 is equipped with an upper electrode assembly 2, a lower electrode assembly 3, a gantry frame 4, a lead screw assembly 5, and a distance sensor 6; the distance sensor 6 is grouped on the upper electrode assembly 2, the lower electrode assembly 3 is fixed to the bottom of the vacuum chamber 1, and the upper electrode assembly 2 is fixedly connected to the gantry frame 4; both ends of the gantry frame 4 are respectively connected to the corresponding lead screw assemblies 5, which can adjust the distance and angle between the upper electrode assembly 2 and the workpiece 10; a process gas inlet pipe 11 and a process gas outlet pipe 12 are inserted into the shell of the vacuum chamber 1 (during the processing, it is necessary to continuously evacuate the vacuum chamber 1 from the process gas outlet pipe 12 to maintain the vacuum level of the reaction process on the one hand, and to continuously extract the reaction products and discharge them from the vacuum chamber 1).

[0030] In this embodiment, the upper electrode assembly 2 includes an upper insulating ring 201, a gas distributor 202, and an upper electrode gas nozzle 203; the gas distributor 202 is connected to the process gas inlet pipe 11, and the gas distributor 202 is fixedly connected to the gantry 4 through the upper insulating ring 201; the lower end of the gas distributor 202 is connected to the upper electrode gas nozzle 203. The process gas inlet pipe 11 can transport the process gas to the gas distributor 202 for uniform distribution, and then spray it into the gap between the upper electrode assembly 2 and the lower electrode assembly 3 through the upper electrode gas nozzle 203.

[0031] In this embodiment, the lower electrode assembly 3 includes a lower electrode workbench 301 and a rotating motor 302; the stator part of the rotating motor 302 is fixedly connected to the bottom of the vacuum chamber 1, and the rotor part of the rotating motor 302 is connected to the lower electrode workbench 301; a temperature sensor and a cooling system 7 are provided inside the lower electrode workbench 301.

[0032] In this embodiment, the distance sensors 6 are evenly arranged along the circumferential direction of the upper electrode gas nozzle 203, and the number is 6.

[0033] In this embodiment, the cooling system 7 includes a cooling pipe 701, a coolant inlet 702, and a coolant outlet 703. The cooling pipe 701 is provided inside the lower electrode workbench 301, and the coolant inlet 702 and the coolant outlet 703 are provided at both ends of the lower electrode workbench 301; the cooling pipe 701 is respectively connected to the coolant storage tank 8 through the coolant inlet 702 and the coolant outlet 703. A cooling pump 9 is provided between the coolant storage tank 8 and the coolant inlet 702. The cooling pump 9 can pump the cooling water from the coolant storage tank 8 into the cooling pipe 701, exchange heat with the lower electrode workbench 301, and then flow back into the coolant storage tank 8.

[0034] In this embodiment, the cooling pipe 701 is distributed in a "U" shape inside the lower electrode workbench 301. The "U" shape distribution increases the contact area between the cooling pipe 701 and the lower electrode workbench 301, thereby improving the cooling efficiency.

[0035] In this embodiment, the screw rod assembly 5 includes a screw rod frame 501 and an adjustment slider 503. Two adjustment motors 502 are provided on the screw rod frame 501, and the output ends of the adjustment motors 502 are connected with screw rods 504; the adjustment slider 503 is in clearance fit with the two screw rods 504 at the same time to form a transmission connection. The gantry 4 is fixedly connected to the adjustment slider 503, so that the position of the gantry 4 can be adjusted by the adjustment motor 502 (the clearance fit between the screw rod 2 and the adjustment slider 503 can achieve the single adjustment of the screw rod 2, thereby performing a fine angle adjustment on the gantry 2 to make the upper electrode nozzle 203 and the workpiece 10 parallel).

[0036] In this embodiment, the upper electrode gas nozzle 203 is made of high-purity aluminum. High-purity aluminum has excellent electrical conductivity, and using it as the material for the upper electrode nozzle 203 can enhance the adsorption capacity of the upper electrode nozzle 203 surface for process gases, thereby improving discharge efficiency.

[0037] In this embodiment, the surface of the upper electrode gas nozzle 203 is roughened. This roughening process involves creating tiny structures on the surface of the upper electrode nozzle 203, which increases the surface area of ​​the upper electrode nozzle 203 and improves the plasma generation efficiency.

[0038] In this embodiment, the gas distributor 202 and the upper electrode gas nozzle 203 are connected to each other via threads. Using threads to connect the gas distributor 202 and the upper electrode gas nozzle 203 is easy to implement.

[0039] In this embodiment, the specific process for precise adjustment of the electrode gap is as follows:

[0040] Before processing begins, the adjustment motor 502 controls the position of the adjustment slider 503 according to the detection data of the distance sensor 6, adjusts the distance between the upper electrode gas nozzle 203 and the workpiece 10 to the set value, and at the same time, adjusts the upper electrode gas nozzle 203 and the workpiece 10 to be parallel for initial positioning.

[0041] During the processing, the total thickness of the workpiece 10 decreases, the distance between the gas nozzle 203 and the workpiece 10 increases, the distance sensor 6 detects a deviation between the distance and the set value, and the adjusting motor 502 will make a slight adjustment to compensate for the deviation.

[0042] In an experiment using the plasma etching apparatus of the above embodiment, a silicon carbide wafer with a diameter of 150 mm and a thickness of 350 μm was selected for processing. Before processing, the position of the adjusting slider 503 was precisely controlled by the motor 502 to adjust the distance between the upper electrode gas nozzle 203 and the workpiece 10 to 2 mm for initial positioning. The vacuum chamber 1 was evacuated to 1.5 torr, and process gas (including CF4 and SF6) was introduced into the vacuum chamber 1. The process gas was uniformly introduced into the upper electrode gas nozzle 203 through the gas distributor 202, and sprayed from the upper electrode gas nozzle 203 to the space between the upper electrode gas nozzle 203 and the lower electrode stage 301. The gas flow rate was 1500 sccm.

[0043] When the power is turned on, a high-frequency electric field is formed between the upper electrode gas nozzle 203 and the lower electrode stage 301. The radio frequency power parameter is 900W, which excites the reactive gas to form plasma between the upper and lower electrodes. The ions in the plasma are attracted and accelerated by the lower electrode stage 301, rushing towards the workpiece 10 at high speed to remove the material from the surface of the workpiece 10.

[0044] During the processing, the distance sensor 6 continuously monitors the distance between the upper electrode gas nozzle 203 and the workpiece 10 in real time to verify whether the preset processing conditions are met. As the surface of the workpiece 10 is continuously etched, the distance sensor 6 detects that the distance between the upper electrode gas nozzle 203 and the workpiece 10 deviates from the set value. The adjustment motor 502 will make a slight adjustment to compensate for this deviation, thereby maintaining the processing accuracy.

[0045] Once the predetermined process conditions are met, the power supply is stopped, the plasma gradually dissipates, and the etching process ends. The material removal rate is measured to be 15 μm / h.

[0046] The foregoing general description of the invention and its specific embodiments should not be construed as a limitation on the technical solution of the invention. Those skilled in the art, based on the disclosure of this application, can add, reduce, or combine the disclosed technical features in the foregoing general description and / or specific embodiments (including examples) without departing from the constituent elements of the invention, to form other technical solutions within the scope of protection of this application.

Claims

1. A plasma etching apparatus with precisely adjustable electrode gap, comprising a vacuum chamber (1); characterized in that: The vacuum chamber (1) is equipped with an upper electrode assembly (2), a lower electrode assembly (3), a gantry frame (4), a lead screw assembly (5), and a distance sensor (6). The distance sensor (6) is arranged in groups on the upper electrode assembly (2). The lower electrode assembly (3) is fixed to the bottom of the vacuum chamber (1). The upper electrode assembly (2) is fixedly connected to the gantry frame (4). The two ends of the gantry frame (4) are respectively connected to the corresponding lead screw assembly (5), which can adjust the distance and angle between the upper electrode assembly (2) and the workpiece (10). A process gas inlet pipe (11) and a process gas outlet pipe (12) are inserted into the shell of the vacuum chamber (1). The upper electrode assembly (2) includes an upper insulating ring (201), a gas distributor (202), and an upper electrode gas nozzle (203); the gas distributor (202) is connected to the process gas inlet pipe (11), and the gas distributor (202) is fixedly connected to the gantry (4) through the upper insulating ring (201); the lower end of the gas distributor (202) is connected to the upper electrode gas nozzle (203), and the process gas inlet pipe (11) can transport the process gas to the gas distributor (202) for uniform distribution, and then spray it into the gap between the upper electrode assembly (2) and the lower electrode assembly (3) through the upper electrode gas nozzle (203); The lower electrode assembly (3) includes a lower electrode worktable (301) and a rotary motor (302); the stator of the rotary motor (302) is fixedly connected to the bottom of the vacuum chamber (1), and the rotor of the rotary motor (302) is connected to the lower electrode worktable (301); the lower electrode worktable (301) is equipped with a temperature sensor and a cooling system (7). The distance sensors (6) are evenly arranged along the circumference of the upper electrode gas nozzle (203), and the number is 3-10. The lead screw assembly (5) includes a lead screw frame (501) and an adjusting slider (503). The lead screw frame (501) is equipped with two adjusting motors (502), and the output end of the adjusting motors (502) is connected to a lead screw (504). The adjusting slider (503) is in clearance fit with the two lead screws (504) to form a transmission connection. The gantry frame (4) is fixedly connected to the adjusting slider (503), so that the position of the gantry frame (4) can be adjusted by adjusting the adjusting motors (502). The surface of the upper electrode gas nozzle (203) is roughened.

2. The plasma etching apparatus with precisely adjustable electrode gap according to claim 1, characterized in that: The cooling system (7) includes a cooling pipe (701), a coolant inlet (702), and a coolant outlet (703). The cooling pipe (701) is disposed within the lower electrode table (301), and the coolant inlet (702) and the coolant outlet (703) are disposed at both ends of the lower electrode table (301). The cooling pipe (701) is connected to a coolant storage tank (8) through the coolant inlet (702) and the coolant outlet (703) respectively. A cooling pump (9) is provided between the coolant storage tank (8) and the coolant inlet (702). The cooling pump (9) can pump cooling water from the coolant storage tank (8) into the cooling pipe (701), exchange heat with the lower electrode table (301), and then flow back into the coolant storage tank (8).

3. The plasma etching apparatus with precisely adjustable electrode gap according to claim 2, characterized in that: The cooling pipe (701) is distributed in a "U" shape within the lower electrode table (301).

4. The plasma etching apparatus with precisely adjustable electrode gap according to claim 1, characterized in that: The material of the upper electrode gas nozzle (203) is high-purity aluminum.

5. The plasma etching apparatus with precisely adjustable electrode gap according to claim 1, characterized in that: The gas distributor (202) and the upper electrode gas nozzle (203) are connected to each other by threads.

6. A method for precisely adjusting the electrode gap of a plasma etching apparatus, characterized in that: This adjustment method is used to adjust the electrode spacing of the plasma etching device according to Claim 1, and the process is as follows: Before the start of processing, the adjustment motor (502) controls the position of the adjustment slider (503) according to the monitoring data of the distance sensor (6), adjusts the distance between the upper electrode gas nozzle (203) and the workpiece (10) to a set value. At the same time, the upper electrode gas nozzle (203) and the workpiece (10) are adjusted to be parallel for initial positioning. During the processing, the total thickness of the workpiece (10) becomes smaller, the distance between the gas nozzle (203) and the workpiece (10) becomes larger, and the distance sensor (6) detects that the distance deviates from the set value. The adjustment motor (502) makes a fine adjustment to compensate for the deviation.

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