A plasma source system and a method for using the same

Abstract

The present application provides a plasma source system and a method for using the same, belonging to the technical field of plasma etching. Specifically, it includes a reaction chamber main body; an inductively coupled radio frequency unit located above the reaction chamber main body, and the inductively coupled radio frequency unit is used to generate plasma that enters the reaction chamber main body to participate in the reaction; a support platform and a cavity protection ring with adjustable position are arranged in the reaction chamber main body. The support platform is used to place wafers, the cavity protection ring is arranged around the inner wall of the reaction chamber main body and is located around the support platform. The cavity protection ring is provided with a plurality of magnetic members along the circumferential direction, and the magnetic members are used to adjust the plasma density at the edge of the wafer. Through the processing solution of the present application, the uniformity of the etching rate on the wafer surface is improved, and the reaction chamber main body is effectively protected.

Description

Technical Field

[0001] This application relates to the field of plasma etching technology, and particularly to a plasma source system and a method for using the same. Background Art

[0002] Currently, in a typical plasma etching process, different process gas combinations form plasma under the action of radio frequency excitation in a radio frequency environment. The formed plasma undergoes physical bombardment and chemical reactions with the wafer surface under the action of the electric fields of the upper and lower electrodes in the etching chamber, completing the processing of the designed pattern and key processes on the wafer surface. Usually, due to the reasons of the chamber pumping path, there is more or less a situation where the plasma density at the wafer edge is weak, or it can be explained that the concentration of plasma active reaction groups and the ion density show a trend of gradually decreasing from the center to the edge on the upper surface of the wafer due to the pumping action. This gradient trend usually causes the etching rate on the wafer surface to show a distribution with a high middle and a low edge, and there is a problem of uneven etching rate distribution. Summary of the Invention

[0003] In view of this, embodiments of this application provide a plasma source system and a method for using the same, which at least partially solve the problem of uneven etching rate at the wafer edge existing in the prior art.

[0004] In a first aspect, embodiments of this application provide a plasma source system, including:

[0005] A reaction chamber main body;

[0006] An inductively coupled radio frequency unit located above the reaction chamber main body, and the inductively coupled radio frequency unit is used to generate plasma that enters the reaction chamber main body to participate in the reaction;

[0007] A support platform and a position-adjustable chamber protection ring are provided in the reaction chamber main body. The support platform is used to place the wafer. The chamber protection ring is arranged around the inner wall of the reaction chamber main body and is located around the support platform. The chamber protection ring is provided with a plurality of magnetic members along the circumferential direction, and the magnetic members are used to adjust the plasma density at the wafer edge.

[0008] According to a specific implementation manner of embodiments of this application, a moving actuator is connected to the bottom of the chamber protection ring, and the moving actuator drives the chamber protection ring to move up and down.

[0009] According to a specific implementation manner of embodiments of this application, the moving actuator is a multi-threaded cylinder or a servo motor.

[0010] According to a specific implementation manner of embodiments of this application, the chamber protection ring is arranged in a segmented structure along the circumferential direction, and the position of each segment of the chamber protection ring can be adjusted independently.

[0011] According to a specific implementation manner of an embodiment of the present application, the magnetic member is disposed on the cavity protection ring by being sealed into the interior of the cavity protection ring by means of vacuum welding and sealing, or is mounted on the outer wall of the cavity protection ring.

[0012] According to a specific implementation manner of an embodiment of the present application, the inductive coupling radio frequency unit includes:

[0013] A shielding cover;

[0014] A reaction chamber dielectric tube located inside the shielding cover;

[0015] An antenna system located inside the shielding cover and distributed on the side of the reaction chamber dielectric tube, the antenna system being configured to generate plasma inside the reaction chamber dielectric tube, and the plasma being configured to enter between the support platform and the reaction chamber dielectric tube through the reaction chamber dielectric tube;

[0016] A radio frequency power supply; and

[0017] A radio frequency matcher, one end of the radio frequency matcher is connected to the radio frequency power supply, the other end of the radio frequency matcher is connected to one end of the antenna system, and the other end of the antenna system is grounded.

[0018] According to a specific implementation manner of an embodiment of the present application, the inductive coupling radio frequency unit further includes: an intake pipe located at the top of the reaction chamber dielectric tube, and the intake pipe is configured to introduce an etching gas for etching a wafer into the reaction chamber dielectric tube.

[0019] According to a specific implementation manner of an embodiment of the present application, the plasma source system further includes a cooling device, the cooling device is located at the top of the shielding cover, and the cooling device is configured to cool the radio frequency antenna and the reaction chamber dielectric tube.

[0020] According to a specific implementation manner of an embodiment of the present application, the material of the cavity protection ring is aluminum alloy or ceramic, and a hard anodic oxidation protection layer or a yttrium oxide protection layer is provided on the surface of the aluminum alloy.

[0021] In a second aspect, an embodiment of the present application further provides a method for using a plasma source system as described in any one of the embodiments of the first aspect above, and the method includes:

[0022] Adjust the position of the cavity protection ring and transfer the wafer into the reaction chamber main body;

[0023] Adjust the position of the cavity protection ring and the number of magnetic components according to the density requirement of the plasma at the wafer edge. The inductively coupled radio frequency unit generates plasma, and the plasma enters the reaction chamber main body to etch the wafer.

[0024] After the etching is completed, adjust the position of the cavity protection ring again, and transfer the wafer out of the reaction chamber main body.

[0025] Advantageous Effects

[0026] In the plasma source system and its usage method in the embodiments of the present application, by providing an adjustable-position magnetic cavity protection ring inside the reaction chamber main body, an angular electric field E parallel to the cavity protection ring (or the wafer edge) can be induced at a position close to the wafer edge. The density of the plasma at the wafer edge is enhanced under the action of the angular electric field E, thereby achieving the effect of compensating for the non-uniform etching rate at the wafer edge. Moreover, by adjusting the position of the magnetic component, the intensity of the enhancement effect of the plasma at the wafer edge can be regulated, so as to meet the adjustment requirements of different process processes. The cavity protection ring can also isolate and protect the inner wall of the reaction chamber main body, prevent process by-products from depositing on the inner wall of the cavity, and play a role in rapid maintenance. Description of the Drawings

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0028] Figure 1 Structural diagram of a plasma source system according to an embodiment of the present invention;

[0029] Figure 2 Spatial distribution diagram of the wafer etching rate in the prior art;

[0030] Figure 3 Structural diagram of a cavity protection ring according to an embodiment of the present invention;

[0031] Figure 4 Structural diagram of a cavity protection ring according to an embodiment of the present invention;

[0032] Figure 5 Flowchart of the usage method of a plasma source system according to an embodiment of the present invention.

[0033] In the figure: 1, support platform; 2, wafer; 3, plasma; 4, reaction chamber dielectric tube; 5, antenna system; 6, shield; 7, intake pipe; 8, cooling fan; 9, reaction chamber main body; 10, RF matcher; 11, RF power supply; 12, cavity protection ring; 13, moving actuator; 14, magnetic part; 15, air extraction port; 16, wafer transfer port. Detailed implementation manners

[0034] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0035] The following uses specific specific examples to illustrate the implementation manners of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0036] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present application, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, this device and / or this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0037] It should also be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner. The drawings only show the components related to the present application, rather than being drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in its actual implementation can be an arbitrary change, and the component layout type may also be more complex.

[0038] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0039] In a first aspect, embodiments of the present application provide a plasma source system, which will be described in detail below with reference to the figures.

[0040] Referring to Figure 1 , the plasma source includes a reaction chamber main body 9 and an inductively coupled radio frequency unit located above the reaction chamber main body 9. The inductively coupled radio frequency unit is used to generate plasma 3 that enters the reaction chamber main body 9 to participate in the reaction.

[0041] Specifically, a support platform 1 and a cavity protection ring 12 with adjustable position are provided in the reaction chamber main body 9. The support platform 1 is used to place the wafer 2. A wafer transfer port 16 is provided on the side wall of the reaction chamber main body 9 for the incoming and outgoing of the wafer 2. An air extraction port 15 is also provided on the lower side of the reaction chamber main body 9 for extracting the gas in the cavity. The cavity protection ring 12 is arranged around the inner wall of the reaction chamber main body 9 and is located around the support platform 1. A plurality of magnetic members 14 are provided on the cavity protection ring 12 along the circumferential direction. The magnetic members 14 are used to adjust the density of the plasma 3 at the edge of the wafer 2. In this embodiment, the magnetic members 14 are arranged around the periphery of the wafer 2. The magnetic field H between the magnetic members 14 induces an angular electric field E parallel to the cavity protection ring 12 (or the edge of the wafer 2) at a position near the edge of the wafer 2 inside the cavity protection ring 12. The density of the plasma 3 at the edge of the wafer 2 is enhanced by the action of the angular electric field E, thereby achieving the effect of compensating for the uneven etching rate at the edge of the wafer 2.

[0042] In a preferred embodiment, a moving actuator 13 is connected to the bottom of the cavity protection ring 12. The moving actuator 13 drives the cavity protection ring 12 to move up and down to adapt to the incoming and outgoing of the wafer 2 into and out of the reaction chamber main body 9, and when the wafer 2 is in different reaction stages, the moving actuator 13 drives the cavity protection ring 12 to move up and down, thereby adjusting the position of the magnetic members 14 relative to the wafer 2, and further adjusting the density of the plasma 3 at the edge of the wafer 2.

[0043] Preferably, the moving actuator 13 is a multi-threaded cylinder or a servo motor.

[0044] In one embodiment, referring to Figure 3 , the cavity protection ring 12 can be set as an integral structure, and the magnetic members 14 are uniformly arranged inside the side wall of the cavity protection ring 12. In this setting method, the angular electric field E generated by the uniformly arranged magnetic members 14 is uniform, so it is applicable to the case where the density of the plasma 3 at the edge of the wafer 2 is relatively uniform.

[0045] In order to better adapt to the density asymmetry of the plasma 3 around the wafer 2 during the etching process, the cavity protection ring 12 is arranged as a segmented structure along the circumferential direction, that is, the cavity protection ring 12 is set as a plurality of connected arc segments, referring to Figure 4, the cavity protection ring 12 is evenly divided into 4 arc segments, and the position of each segment of the cavity protection ring 12 can be adjusted independently. The number of magnetic components 14 provided on each segment of the cavity protection ring 12 can be adjusted according to actual needs. The magnetic components 14 can be evenly distributed on each segment of the cavity protection ring 12, or the number of magnetic components 14 on each segment of the cavity protection ring 12 is different.

[0046] In one embodiment, the number of arc segments is greater than or equal to 3.

[0047] In one embodiment, the magnetic component 14 is disposed on the cavity protection ring 12 by being sealed into the interior of the cavity protection ring 12 by means of vacuum welding and sealing, or is mounted on the outer wall of the cavity protection ring 12.

[0048] In one embodiment, the material of the cavity protection ring 12 is a dielectric material such as aluminum alloy or ceramic. The surface of the aluminum alloy is provided with a hard anodic oxidation protective layer or a yttrium oxide protective layer to protect the aluminum alloy.

[0049] The inductive coupling radio frequency unit will be specifically described below. The inductive coupling radio frequency unit includes a shielding cover 6 and a reaction chamber dielectric tube 4 located inside the shielding cover 6; it further includes an antenna system 5 located inside the shielding cover 6 and distributed on the side of the reaction chamber dielectric tube 4. The antenna system 5 is used to generate plasma 3 inside the reaction chamber dielectric tube 4, and the plasma 3 is used to enter between the support platform 1 and the reaction chamber dielectric tube 4 through the reaction chamber dielectric tube 4.

[0050] The inductive coupling radio frequency unit further includes a radio frequency power supply 11 located outside the shielding cover 6, and a radio frequency matcher 10. One end of the radio frequency matcher 10 is connected to the radio frequency power supply 11, the other end of the radio frequency matcher 10 is connected to one end of the antenna system 5, and the other end of the antenna system 5 is grounded.

[0051] In one embodiment, the side wall of the reaction chamber dielectric tube 4 is inclined and the top cross-section of the reaction chamber dielectric tube 4 is smaller than the bottom cross-section. Refer to Figure 1 The longitudinal section of the reaction chamber dielectric tube 4 in [reference] is a trapezoidal structure; in another embodiment, the longitudinal section of the reaction chamber dielectric tube 4 is a rectangular structure, that is, the side wall of the reaction chamber dielectric tube 4 is set perpendicular to the top of the shielding cover 6.

[0052] In one embodiment, the longitudinal profile shape of the reaction chamber dielectric tube 4 is trapezoidal or conical.

[0053] In one embodiment, the inductive coupling radio frequency unit further includes: an intake pipe 7 located at the top of the reaction chamber dielectric tube 4, and the intake pipe is used to introduce an etching gas for etching the wafer 2 into the reaction chamber dielectric tube 4.

[0054] In the above embodiment, the antenna system 5 includes a radio frequency antenna, and the radio frequency antenna surrounds the reaction chamber dielectric tube 4 and has a multi-turn continuous coil.

[0055] In a preferred embodiment, the plasma source system further includes a cooling device located at the top of the shielding cover 6, and the cooling device is used to cool the radio frequency antenna and the reaction chamber dielectric tube 4.

[0056] Preferably, the cooling device is set as a cooling fan 8.

[0057] In the existing technology, during the process that the plasma 3 is formed in the reaction chamber dielectric tube 4 and diffuses to the reaction chamber main body 9, there is a certain three-dimensional spatial distribution of the plasma density. Usually, due to the reason of the cavity pumping path, there is more or less a situation where the plasma density at the wafer edge is weak, or it can be explained that due to the pumping effect, the concentration of plasma active reaction groups and the ion density show a trend of gradually decreasing from the center to the edge on the upper surface of the wafer. This gradient trend usually causes the etching rate on the wafer surface to show a distribution of high in the middle and low at the edge, as Figure 2 shown by the etching rate curve H1. In addition, due to the differences in gas types, gas pressures, and radio frequency power magnitudes in different reaction processes, the degree of high in the middle and low at the edge of the etching rate distribution curve will also be different, as Figure 2 shown by the etching rate curves H1, H2, and H3.

[0058] Based on this problem of uneven etching rate distribution, the present application proposes a magnetically adjustable cavity protection ring structure. The working principle of the cavity protection ring 12 is as follows: A number of magnetically conductive members 14 distributed along the circumference are integrated on the cavity protection ring 12. In one embodiment, the magnetically conductive member 14 is a permanent magnet, and a circumferential electric field E parallel to the cavity protection ring 12 (or the wafer edge) will be induced at the edge position near the wafer 2 inside the structure of the cavity protection ring 12 by the magnetic field H between the permanent magnets; the density of the plasma at the wafer 2 edge is enhanced by the action of the circumferential electric field E, so as to achieve the effect of compensating the etching rate at the wafer 2 edge. The structure of the cavity protection ring 12 can be moved up and down, aiming to adjust the intensity of the plasma enhancement effect at the wafer 2 edge, so as to meet the adjustment requirements of different process processes. In addition, due to the fact that some process by-products cannot be pumped away in time, they usually deposit on the inner wall of the cavity, resulting in poor maintainability of the cavity; the cavity protection ring 12 can isolate and protect the inner wall of the reaction chamber main body 9, prevent process by-products from depositing on the inner wall of the cavity, and play a role of quick maintenance.

[0059] In a second aspect, the embodiments of the present application further provide a method for using a plasma source system according to any one of the embodiments in the first aspect above. The method includes:

[0060] Adjust the position of the cavity protection ring 12 and transfer the wafer 2 into the reaction chamber main body 9;

[0061] Adjust the position of the cavity protection ring 12 and the number of magnetic components according to the density requirement of the plasma at the edge of the wafer 2. The inductively coupled radio frequency unit generates plasma, and the plasma enters the reaction chamber main body 9 to etch the wafer 2;

[0062] After the etching is completed, adjust the position of the cavity protection ring 12 again, and transfer the wafer 2 out of the reaction chamber main body 9.

[0063] Specifically, referring to Figure 5 , the usage method of the plasma source system includes the following steps:

[0064] (a) Wafer 2 transfer: Use the moving actuator 13 to drive the cavity protection ring 12 to move downward, so that the top of the cavity protection ring 12 is lower than the wafer transfer port 16, and transfer the wafer 2 from the wafer transfer port 16 to the support platform 1;

[0065] (b) Reaction stage 1: Use the moving actuator 13 to drive the cavity protection ring 12 to move upward. According to the requirement of the plasma 3 concentration at the edge of the wafer 2 in reaction stage 1, adjust the cavity protection ring 12 to a suitable position for plasma etching;

[0066] (c) Reaction stage 2: Use the moving actuator 13 to drive the cavity protection ring 12 to continue moving upward. According to the requirement of the plasma 3 concentration at the edge of the wafer 2 in reaction stage 2, adjust the cavity protection ring 12 to a suitable position for plasma etching;

[0067] Continue to adjust the position of the cavity protection ring 12 for etching until the etching is completed;

[0068] (d) Wafer transfer out: Use the moving actuator 13 to drive the cavity protection ring 12 to move downward, so that the top of the cavity protection ring 12 is lower than the wafer transfer port 16, and transfer the wafer 2 out of the wafer transfer port 16 to complete the etching process of the entire wafer.

[0069] During the above usage method of the plasma source system, the number of magnetic components 14 on the cavity protection ring 12 can also be adjusted to adjust the plasma 3 concentration distribution at the edge of the wafer 2; or the cavity protection ring 12 can be set as a segmented structure, and the position of each segment of the cavity protection ring 12 and the number of magnetic components 14 thereon are adjusted separately, so as to adjust the plasma 3 concentration distribution at the edge of the wafer 2.

[0070] The plasma source system provided by the embodiments of the present application can induce an azimuthal electric field E parallel to the cavity protection ring (or the edge of the wafer) at a position close to the edge of the wafer by setting a magnetically adjustable cavity protection ring. The density of the plasma at the wafer edge is enhanced under the action of the azimuthal electric field E, thereby achieving the effect of compensating for the uneven etching rate at the wafer edge. Moreover, the intensity of the enhancement effect of the plasma at the wafer edge is adjusted by adjusting the position of the magnetic component, so as to meet the adjustment requirements of different process technologies. The cavity protection ring can also isolate and protect the inner wall of the main body of the reaction chamber, prevent process by-products from depositing on the inner wall of the chamber, and play a role in rapid maintenance.

[0071] As described above, the above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A plasma source system, characterized in that, Comprising: A reaction chamber body; An inductively coupled radio frequency unit located above the reaction chamber body, which is used to generate plasma entering the reaction chamber body to participate in the reaction; A support platform and an adjustable-position cavity protection ring are provided in the reaction chamber body. The support platform is used to place wafers. The cavity protection ring is arranged around the inner wall of the reaction chamber body and is located around the support platform. The cavity protection ring is provided with a plurality of magnetic members along the circumferential direction, and the magnetic members are used to adjust the plasma density at the edge of the wafer; The magnetic field between the magnetic members induces an angular electric field E parallel to the cavity protection ring or the wafer edge at the edge position near the wafer inside the cavity protection ring; By adjusting the number of magnetic members on the cavity protection ring, the plasma concentration distribution at the edge of the wafer is adjusted. Alternatively, the cavity protection ring is set as a segmented structure, and the position of each segment of the cavity protection ring and the number of magnetic members thereon are adjusted separately, so as to adjust the plasma concentration distribution at the edge of the wafer.

2. The plasma source system according to claim 1, wherein A moving actuator is connected to the bottom of the cavity protection ring, and the moving actuator drives the cavity protection ring to move up and down.

3. The plasma source system according to claim 2, wherein The moving actuator is a multi-threaded cylinder or a servo motor.

4. The plasma source system according to claim 1, wherein The magnetic members are arranged on the cavity protection ring by being sealed into the cavity protection ring by vacuum welding, or being installed on the outer wall of the cavity protection ring.

5. The plasma source system according to claim 1, wherein The inductively coupled radio frequency unit includes: A shielding cover; A reaction chamber dielectric tube located inside the shielding cover; An antenna system located inside the shielding cover and distributed on the side of the reaction chamber dielectric tube. The antenna system is used to generate plasma inside the reaction chamber dielectric tube, and the plasma is used to enter the space between the support platform and the reaction chamber dielectric tube through the reaction chamber dielectric tube; A radio frequency power supply; and A radio frequency matcher. One end of the radio frequency matcher is connected to the radio frequency power supply, the other end of the radio frequency matcher is connected to one end of the antenna system, and the other end of the antenna system is grounded.

6. The plasma source system according to claim 5, wherein The inductively coupled radio frequency unit further includes: an intake pipe located at the top of the reaction chamber dielectric tube, and the intake pipe is used to introduce etching gas for etching wafers into the reaction chamber dielectric tube.

7. The plasma source system according to claim 6, wherein The plasma source system further includes a cooling device located at the top of the shielding cover, and the cooling device is used to cool the radio frequency antenna and the reaction chamber dielectric tube.

8. The plasma source system according to any one of claims 1-7, characterized in that, The material of the cavity protection ring is aluminum alloy or ceramic, and a hard anodized protective layer or yttrium oxide protective layer is provided on the surface of the aluminum alloy.

9. A method for using a plasma source system according to any one of claims 1-8, characterized in that, The method includes: Adjusting the position of the cavity protection ring and transferring the wafer into the reaction chamber body; Adjusting the position of the cavity protection ring and the number of magnetic members according to the density requirement of the plasma at the edge of the wafer. The inductively coupled radio frequency unit generates plasma, and the plasma enters the reaction chamber body to etch the wafer; After the etching is completed, adjust the position of the cavity protection ring again and transfer the wafer out of the reaction chamber body.

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