Plasma etching device with precisely adjustable electrode gap and adjusting method

Abstract

The invention discloses a plasma etching device capable of precisely adjusting an electrode gap and an adjusting method.The etching device comprises a vacuum chamber, an upper electrode assembly, a lower electrode assembly, a portal frame, a lead screw assembly and distance sensors are arranged in the vacuum chamber, and the distance sensors are arranged on the upper electrode assembly in a grouped mode; the lower electrode assembly is fixed at the bottom of the vacuum chamber, and the upper electrode assembly is fixedly connected with the portal frame; the two ends of the portal frame are connected with the lead screw assemblies respectively. According to the etching device, the gap and the angle between the upper electrode and the workpiece can be precisely adjusted, uniform distribution of plasmas is promoted, and machining uniformity and consistency are improved; and meanwhile, the cooling system is arranged, so that the temperature fluctuation in the etching device can be effectively controlled. According to the adjusting method, the distance between the upper electrode nozzle and the workpiece can be continuously and precisely adjusted in the etching process, the machining distance between the upper electrode nozzle and the workpiece is kept constant, and more efficient and more stable machining capacity is provided.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor manufacturing, and in particular to a plasma etching device with precisely adjustable electrode gap and an adjustment method. Background Art

[0002] In the field of semiconductor manufacturing, capacitively coupled plasma processing equipment (such as CCP etching equipment) is widely used in key processes such as etching, thin film deposition and sputtering because it can generate large-area plasma. The working principle of plasma etching equipment is based on the principle of capacitive coupling, which uses the principle of parallel plate capacitors to continuously excite and generate plasma. RF power is applied to the two poles of the parallel plate, and the process gas enters the reaction chamber, where plasma is generated under the excitation of the RF power supply. Under the action of the electric field force, the charged particles continuously bombard the surface of the workpiece, thereby removing the material on the surface of the workpiece to achieve the purpose of etching. With the continuous miniaturization and performance improvement of semiconductor devices, the performance requirements for plasma etching equipment are also increasing.

[0003] However, there are some urgent problems in the plasma etching equipment in the prior art, which limit its application efficiency and quality in the semiconductor manufacturing process. The non-uniformity of plasma density can lead to azimuthal asymmetry of etching rate or critical dimensions, which in turn affects the etching effect and yield. In order to improve the uniformity of plasma, researchers have tried a variety of methods, including taking magnetic shielding measures to correct the non-uniformity caused by the earth's magnetic field induction, and adjusting the electrode gap technology to achieve uniform ion flux on the surface of the silicon wafer.

[0004] In plasma etching equipment, the distance between electrode plates directly determines the movement range and collision frequency of electrons in high-frequency electric fields. When the gap between electrode plates increases, the movement path of electrons between electrode plates becomes longer, the number of collisions may decrease, and the plasma density decreases. Conversely, when the gap between electrode plates decreases, the collision frequency of electrons increases, which helps to produce a higher density plasma. In addition, the adjustment of the gap between electrode plates can also affect the uniformity of plasma distribution and ensure the consistency and accuracy of the etching process. However, the existing plasma etching equipment has low accuracy when adjusting the electrode plates, resulting in low surface uniformity and consistency of the workpiece after processing; during the processing, the material on the surface of the workpiece is continuously removed, resulting in a larger distance between the workpiece and the upper electrode plate, affecting the etching efficiency and effect. In addition, since the vacuum processing environment cannot dissipate heat in time, the device will produce local overheating, resulting in poor processing stability, which not only affects the uniformity of workpiece processing, but also may shorten the service life of the equipment. Summary of the invention

[0005] In order to overcome the deficiencies in the prior art, the present invention provides a plasma etching device and an adjustment method with precisely adjustable electrode gap; the plasma etching device of the present invention can precisely adjust the gap between the upper electrode plate and the workpiece, ensure the parallelism between the upper electrode plate and the workpiece, maintain a constant processing distance between the upper electrode plate and the workpiece, promote the uniform distribution of plasma on the surface of the workpiece, provide more efficient and more stable processing capabilities, meet the needs of high-precision semiconductor processing, and further improve the uniformity and consistency of processing; the etching device of the present invention is also provided with a cooling system, which can effectively control the temperature fluctuations in the etching device, make the working environment more stable, ensure the processing quality, prevent the device from being damaged due to local overheating, and extend the service life of the device; in addition, the present invention also provides a method for precisely adjusting the electrode gap, by which the distance between the upper electrode nozzle and the workpiece can be continuously and precisely adjusted during the etching process, the processing distance between the upper electrode nozzle and the workpiece can be maintained constant, and more efficient and more stable processing capabilities can be provided.

[0006] For the plasma etching device, the technical solution of the present invention is as follows:

[0007] A plasma etching device with a precisely adjustable electrode gap comprises a vacuum chamber; an upper electrode assembly, a lower electrode assembly, a gantry, a lead screw assembly and a distance sensor are arranged in the vacuum chamber; the distance sensors are arranged in groups 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; the two ends of the gantry are respectively connected to the corresponding lead screw assemblies, and the distance and angle between the upper electrode assembly and the workpiece can be adjusted; a process gas inlet pipe and a process gas outlet pipe are inserted into the shell of the vacuum chamber; the upper electrode assembly comprises 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 the gas distributor is fixedly connected to the gantry through the upper insulating ring; the lower end of the gas distributor is connected to the upper electrode gas nozzle, and the process gas inlet pipe can transport the process gas to the gas distributor for uniform distribution, and then spray it into the gap between the upper electrode assembly and the lower electrode assembly through the upper electrode gas nozzle; the lower electrode assembly includes a lower electrode workbench and a rotating motor; the stator part of the rotating motor is fixedly connected to the bottom of the vacuum chamber, and the rotor part of the rotating motor is connected to the lower electrode workbench; a temperature sensor and a cooling system are arranged in the lower electrode workbench.

[0008] Compared with the prior art, the plasma etching device with precisely adjustable electrode gap of the present invention has made significant progress, as follows:

[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 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 needs of high-precision semiconductor processing. In addition, the etching device of the present invention is equipped with a rotating motor at the bottom of the lower electrode workbench, which can drive the workpiece to rotate synchronously at a uniform speed during the processing process, promote the uniform distribution of plasma in the processing area, and further improve the uniformity and consistency of the processing.

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

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

[0012] Furthermore, in the above-mentioned 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 in 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 connected to the coolant storage tank through the coolant inlet and the coolant outlet respectively, and a cooling pump is arranged between the coolant storage tank and the coolant inlet. The cooling pump can pump cooling water from the coolant storage tank into the cooling pipe, and then flow back to the coolant storage tank after heat exchange with the lower electrode workbench. Further, the cooling pipe is distributed in the shape of a "J" in the lower electrode workbench. The "J"-shaped distribution increases the contact area between the cooling pipe and the lower electrode workbench, thereby improving the cooling efficiency.

[0013] Furthermore, in the above-mentioned plasma etching device with precisely adjustable electrode gap, the screw assembly includes a screw rack and an adjustment slider, the screw rack is provided with two adjustment motors, and the output end of the adjustment motor is connected to a screw; the adjustment slider is simultaneously matched with the gaps of the two screws 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 above-mentioned plasma etching device with precisely adjustable electrode gap, the material of the upper electrode gas nozzle is high-purity aluminum. High-purity aluminum has excellent electrical conductivity. Using it as the material of the upper electrode nozzle can enhance the adsorption capacity of the upper electrode nozzle surface for process gas and improve the discharge efficiency. Further, the surface of the upper electrode gas nozzle is roughened. This roughening treatment involves manufacturing tiny structures on the surface of the upper electrode nozzle, which can increase the surface area of ​​the upper electrode nozzle and improve the efficiency of plasma generation.

[0015] Furthermore, in the above-mentioned plasma etching device with precisely adjustable electrode gap, the gas distributor and the upper electrode gas nozzle are connected to each other through threads. The connection between the gas distributor and the upper electrode gas nozzle is realized by threads, which has the characteristic of being easy to implement.

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

[0017] A method for precisely adjusting the gap between electrodes of a plasma etching device is provided. The method is used to adjust the gap between electrodes of the plasma etching device. The process is as follows:

[0018] Before the start of processing, the adjustment motor controls the position of the adjustment slide according to the detection data of the distance sensor, adjusts the distance between the upper electrode gas nozzle and the workpiece to the set value, and at the same time, adjusts the upper electrode gas nozzle and the workpiece to be parallel to perform initial positioning;

[0019] During the machining process, the total thickness of the workpiece becomes smaller, the distance between the gas nozzle and the workpiece becomes larger, and the distance sensor detects that there is a deviation between the distance and the set value. The adjustment motor will make slight adjustments to compensate for the deviation.

[0020] Compared with the prior art, the adjustment method of the present invention adopts the above-mentioned plasma etching device with precisely 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 stable processing capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of a plasma etching device with precisely adjustable electrode gap according to the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the gas nozzle of the upper electrode in the plasma etching device with precisely adjustable electrode gap of the present invention;

[0023] Figure 3 It is a schematic structural diagram of the lower electrode assembly in the plasma etching device with precisely adjustable electrode gap of the present invention;

[0024] Figure 4 It is a structural schematic diagram of a lead screw assembly in a plasma etching device with a precisely adjustable electrode gap according to the present invention;

[0025] Figure 5 It is a structural schematic diagram of a cooling system in a plasma etching device with precisely adjustable electrode gap according to the present invention.

[0026] The markings in the accompanying drawings are: 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 workbench; 302-rotating motor; 4-gantry; 5-screw assembly; 501-screw rack; 502-adjustment motor; 503-adjustment 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 DESCRIPTION

[0027] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not used as the basis of the present invention. The contents not described in detail in the following embodiments are all common technical knowledge in the art.

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

[0029] A plasma etching device with a precisely adjustable electrode gap comprises a vacuum chamber 1; an upper electrode assembly 2, a lower electrode assembly 3, a gantry 4, a screw assembly 5 and a distance sensor 6 are arranged in the vacuum chamber 1; the distance sensor 6 is arranged in a group 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 4; the two ends of the gantry 4 are respectively connected to the corresponding screw assembly 5, and the distance and angle between the upper electrode assembly 2 and the workpiece 10 can be adjusted; 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, the vacuum chamber 1 needs to be continuously evacuated from the process gas outlet pipe 12, on the one hand to maintain the vacuum degree of the reaction process, and on the other hand to continuously extract the reaction product and discharge it out of 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, 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.

[0031] In this embodiment, the lower electrode assembly 3 includes a lower electrode worktable 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 worktable 301; a temperature sensor and a cooling system 7 are provided in the lower electrode worktable 301.

[0032] In this embodiment, the distance sensors 6 are evenly arranged along the circumference of the upper electrode gas nozzle 203 , and the number of the distance sensors 6 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 arranged in the lower electrode workbench 301, and the coolant inlet 702 and the coolant outlet 703 are arranged at both ends of the lower electrode workbench 301; the cooling pipe 701 is connected to the coolant storage tank 8 through the coolant inlet 702 and the coolant outlet 703 respectively, and a cooling pump 9 is arranged 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, and then flow back to the coolant storage tank 8 after heat exchange with the lower electrode workbench 301.

[0034] In this embodiment, the cooling pipes 701 are distributed in a “J” shape in the lower electrode workbench 301. The “J” shape distribution increases the contact area between the cooling pipes 701 and the lower electrode workbench 301, thereby improving the cooling efficiency.

[0035] In this embodiment, the screw assembly 5 includes a screw frame 501 and an adjustment slider 503, and the screw frame 501 is provided with two adjustment motors 502, and the output end of the adjustment motor 502 is connected to a screw 504; the adjustment slider 503 is clearance-matched with the two screws 504 to form a transmission connection, and 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 2 and the adjustment slider 503 can realize the single adjustment of the screw 2, thereby making a fine angle adjustment of the gantry 2 to make the upper electrode nozzle 203 and the workpiece 10 parallel).

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

[0037] In this embodiment, the surface of the upper electrode gas nozzle 203 is roughened. This roughening process involves manufacturing a tiny structure on the surface of the upper electrode nozzle 203, which can increase the surface area of ​​the upper electrode nozzle 203 and improve the efficiency of plasma generation.

[0038] In this embodiment, the gas distributor 202 and the upper electrode gas nozzle 203 are connected to each other through threads. The connection between the gas distributor 202 and the upper electrode gas nozzle 203 is realized by threads, which has the characteristic of being easy to implement.

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

[0040] Before the processing starts, 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 a set value, and at the same time, adjusts the upper electrode gas nozzle 203 and the workpiece 10 to be parallel to perform initial positioning;

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

[0042] In an experiment using the plasma etching device 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 motor 502 was adjusted to precisely control the position of the adjustment slider 503, and the distance between the upper electrode gas nozzle 203 and the workpiece 10 was adjusted to 2 mm for initial positioning; the vacuum chamber 1 was evacuated to 1.5 torr, and process gas (the process gas included CF4 and SF6) was introduced into the vacuum chamber 1, and the process gas was evenly introduced into the upper electrode gas nozzle 203 through the gas distributor 202, and was sprayed from the upper electrode gas nozzle 203 to between the upper electrode gas nozzle 203 and the lower electrode worktable 301, and 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 workbench 301, and the RF power parameter is 900W, which excites the reaction gas to form plasma between the upper and lower electrodes; the ions in the plasma will be attracted and accelerated by the lower electrode workbench 301, rushing towards the workpiece 10 at high speed to remove the material on 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, and the adjustment motor 502 will make a slight adjustment to compensate for this deviation, thereby maintaining the processing accuracy.

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

[0046] The above general description of the invention involved in this application and the description of its specific implementation methods should not be understood as limiting the technical solutions of the invention. Based on the disclosure of this application, those skilled in the art can add, reduce or combine the disclosed technical features in the above general description and / or specific implementation methods (including examples) without violating the constituent elements of the invention involved, to form other technical solutions within the scope of protection of this application.

Claims

1. A plasma etching device with a precisely adjustable electrode gap, comprising a vacuum chamber (1); characterized in that: The vacuum chamber (1) is provided with an upper electrode assembly (2), a lower electrode assembly (3), a gantry (4), a screw assembly (5) and a distance sensor (6); the distance sensor (6) is arranged in a group 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 (4); the two ends of the gantry (4) are respectively connected to the corresponding screw assembly (5), and the distance and angle between the upper electrode assembly (2) and the workpiece (10) can be adjusted; the shell of the vacuum chamber (1) is provided with a process gas inlet pipe (11) and a process gas outlet pipe (12); The upper electrode assembly (2) comprises an upper insulating ring (201), a gas distributor (202) and an upper electrode gas nozzle (203); the gas distributor (202) is connected to a process gas inlet pipe (11), and the gas distributor (202) is fixedly connected to a gantry (4) via 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 the process gas into the gap between the upper electrode assembly (2) and the lower electrode assembly (3) via the upper electrode gas nozzle (203); The lower electrode assembly (3) comprises a lower electrode worktable (301) and a rotating motor (302); the stator portion of the rotating motor (302) is fixedly connected to the bottom of the vacuum chamber (1), and the rotor portion of the rotating motor (302) is connected to the lower electrode worktable (301); a temperature sensor and a cooling system (7) are provided in the lower electrode worktable (301).

2. The plasma etching device with precisely adjustable electrode gap according to claim 1, characterized in that: The distance sensors (6) are evenly arranged along the circumference of the upper electrode gas nozzle (203), and the number thereof is 3-10.

3. The plasma etching device with precisely adjustable electrode gap according to claim 1, characterized in that: The cooling system (7) comprises a cooling pipeline (701), a cooling liquid inlet (702), and a cooling liquid outlet (703); the cooling pipeline (701) is arranged in the lower electrode workbench (301); the cooling liquid inlet (702) and the cooling liquid outlet (703) are arranged at two ends of the lower electrode workbench (301); the cooling pipeline (701) is connected to a cooling liquid storage tank (8) through the cooling liquid inlet (702) and the cooling liquid outlet (703), respectively; a cooling pump (9) is arranged between the cooling liquid storage tank (8) and the cooling liquid inlet (702); the cooling pump (9) can pump cooling water from the cooling liquid storage tank (8) into the cooling pipeline (701), perform heat exchange with the lower electrode workbench (301), and then flow back to the cooling liquid storage tank (8).

4. The plasma etching device with precisely adjustable electrode gap according to claim 3, characterized in that: The cooling pipes (701) are distributed in a "J" shape inside the lower electrode workbench (301).

5. The plasma etching device with precisely adjustable electrode gap according to claim 1, characterized in that: The screw rod assembly (5) comprises a screw rod frame (501) and an adjustment slider (503); the screw rod frame (501) is provided with two adjustment motors (502); the output end of the adjustment motor (502) is connected to a screw rod (504); the adjustment slider (503) is loosely matched with the two screw rods (504) 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).

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

7. The plasma etching device with precisely adjustable electrode gap according to claim 6, characterized in that: The surface of the upper electrode gas nozzle (203) is roughened.

8. The plasma etching device 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 via threads.

9. A method for precisely adjusting the gap between electrodes of a plasma etching device, characterized in that: The adjustment method is used to adjust the electrode spacing of the plasma etching device of claim 1, and the process is as follows: Before the processing starts, 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, and at the same time, adjusts the upper electrode gas nozzle (203) and the workpiece (10) to be parallel to perform initial positioning; 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 that the distance deviates from the set value, and the adjustment motor (502) performs a slight adjustment to compensate for the deviation.

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