Microwave plasma etching apparatus and method

Abstract

The application discloses a microwave plasma etching device and method, which comprises an etching chamber, a moving platform, a plasma torch, a gas supply assembly and a microwave generator. The moving platform is movably arranged in the etching chamber and used for placing materials to be processed. The plasma torch comprises a nozzle, the nozzle is arranged relative to the moving platform and connected to the inner wall of the etching chamber, the inside of the nozzle is hollow, and the nozzle is provided with a jet hole relative to the moving platform. The gas supply assembly comprises a first gas supply part, the gas outlet end of the first gas supply part is connected to the inside of the nozzle and used for providing plasma generating gas. The microwave generator is connected to the nozzle and used for providing a microwave signal for the nozzle to form a plasma flame. The application can solve the problem that in the prior art, the bias voltage is easily generated due to the discharge of positive and negative electrodes in the plasma forming process, thereby causing electrostatic discharge loss.

Description

Technical Field

[0001] This invention relates to the field of plasma etching technology, and more particularly to a microwave plasma etching apparatus and method. Background Technology

[0002] To improve the surface uniformity of quartz wafers after thickness processing, plasma etching methods have emerged.

[0003] For example, Chinese invention patent application number CN201810534802.9, entitled "A Semiconductor Wafer Etching Apparatus," includes a sealed housing, an electrostatic adsorption platform, an upper electrode plate, a lower electrode plate, a ring-shaped insulating protective plate, an insulating base, an ion buffer module, an automatic gap compensation module, and an ion extraction module. This invention, through the coordinated operation of the ion buffer module, the automatic gap compensation module, and the ion extraction module, can effectively reduce or avoid arc discharge that could damage the lower electrode plate after plasma A becomes conductive with it, thus extending the service life of the semiconductor wafer etching apparatus. However, because the plasma formation process requires positive and negative electrode discharge, a bias voltage is easily generated, leading to electrostatic discharge losses.

[0004] Therefore, there is an urgent need for a microwave plasma etching device and method to solve the problem in the existing technology that bias voltage is easily generated due to the discharge of positive and negative electrodes during plasma formation, which leads to electrostatic discharge loss. Summary of the Invention

[0005] In view of this, it is necessary to provide a microwave plasma etching apparatus and method to solve the technical problem in the prior art that the need for positive and negative electrode discharge during plasma formation can easily generate bias voltage, thereby causing electrostatic discharge loss.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a microwave plasma etching apparatus, comprising:

[0007] Etching chamber;

[0008] A motion platform, which is movably built into the etching chamber, is used to hold the material to be processed;

[0009] A plasma torch includes a nozzle, which is disposed relative to the motion platform and connected to the inner wall of the etching chamber. The nozzle is hollow inside and has a spray hole relative to the motion platform.

[0010] The gas supply assembly includes a first gas supply component, the outlet of which is connected to the interior of the nozzle for supplying plasma generating gas;

[0011] A microwave generator, connected to the nozzle, is used to provide microwave signals to the nozzle to form a plasma flame.

[0012] Furthermore, the sidewall of the nozzle is provided with an air inlet that communicates with the cavity. The plasma torch also includes a coaxial electrode, which is built into the inner hole of the quartz tube and is coaxially arranged with the jet hole. The microwave generator is electrically connected to the coaxial electrode.

[0013] Furthermore, the plasma torch also includes a quartz tube, which is built into the cavity and coaxially sleeved on the coaxial electrode. An air inlet gap is formed between the outer wall of the quartz tube and the inner wall of the cavity. The outer wall of the quartz tube has multiple connecting holes, which are evenly distributed along the circumference of the quartz tube. The air inlet gap is connected to the air inlet holes and the multiple connecting holes.

[0014] Furthermore, the coaxial electrode is helical, and the plasma torch also includes a connecting bracket, one end of which is connected to the nozzle and the other end is inserted into the inner hole of the quartz tube, and the coaxial electrode is sleeved on the connecting bracket.

[0015] Furthermore, the first gas supply component includes three first gas cylinders and a first mixing chamber. The three first gas cylinders are arranged side by side to provide oxygen, carbon tetrafluoride gas or sulfur hexafluoride gas, and argon or helium gas respectively. The inlet end of the first mixing chamber is connected to the outlet end of each of the three first gas cylinders, and the outlet end of the first mixing chamber is connected to the inlet port.

[0016] Furthermore, the bottom of the nozzle has a protrusion relative to the moving platform, and the injection hole penetrates the protrusion.

[0017] Furthermore, the protrusion has an annular cavity, which is coaxially arranged with and communicates with the injection hole. An auxiliary air hole is provided on the outer wall of the protrusion, which is communicated with the annular cavity. The air supply assembly also includes a second air supply component, the outlet of which is communicated with the auxiliary air hole for providing supplementary gas.

[0018] Furthermore, the second gas supply component includes two second gas cylinders arranged side by side, and the outlet ends of the two second gas cylinders are respectively connected to the annular cavity for replenishing carbon tetrafluoride gas or sulfur hexafluoride gas, argon gas or helium gas.

[0019] Furthermore, the second gas supply component also includes a second mixing chamber, the inlet of which is connected to the outlet of the two second gas cylinders, and the outlet of which is connected to the auxiliary air hole.

[0020] The present invention also provides a microwave plasma etching method, which uses the microwave plasma etching apparatus as described in any one of the above-mentioned methods, and includes the following steps:

[0021] S1. Place the quartz wafer to be processed on the motion platform;

[0022] S2. Open the three first gas cylinders and introduce the mixed gas into the first mixing chamber according to the gas supply volume ratio of oxygen: carbon tetrafluoride gas or sulfur hexafluoride gas: argon or helium = 0.01~0.1: 0.01~0.2: 2~5. After the mixture is evenly mixed, introduce it into the inlet gap.

[0023] S3. Start the microwave generator and form plasma in the nozzle, and make the plasma ejected through the injection hole to form an etching process on the surface of the quartz wafer.

[0024] S4. Open the two second gas cylinders and introduce the replenished carbon tetrafluoride or sulfur hexafluoride, argon or helium gas into the nozzle to form a stable plasma flame.

[0025] Compared with existing technologies, the beneficial effects of this invention include: a motion platform built into the etching chamber and capable of translational movement within its own plane for placing materials; the ambient pressure within the etching chamber can be atmospheric pressure or negative vacuum; a nozzle is positioned relative to the motion platform and has injection holes; the outlet end of the first gas supply component is connected to the interior of the nozzle to provide plasma generating gas; and a microwave generator is connected to the nozzle to provide microwave signals to the nozzle to facilitate the formation of a plasma flame. Compared to existing technologies, by using a microwave generator instead of a radio frequency power supply, as the plasma generating gas is continuously introduced, the microwave signal excites the plasma generating gas to form plasma within the cavity, which is then ejected at high speed from the injection holes of the nozzle. The ejected plasma torch can process the surface thickness of the quartz wafer, helping to improve surface uniformity. Furthermore, since plasma formation does not require positive and negative electrodes, no bias voltage is generated, thus solving the technical problem in existing technologies where bias voltage is easily generated due to the need for positive and negative electrode discharge during plasma formation, leading to electrostatic discharge losses. Attached Figure Description

[0026] Figure 1 This is a cross-sectional structural schematic diagram of a microwave plasma etching apparatus provided in an embodiment of the present invention;

[0027] Figure 2 This is a cross-sectional structural schematic diagram of the plasma torch provided in an embodiment of the present invention. Detailed Implementation

[0028] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0029] Please see Figure 1 This invention provides a microwave plasma etching apparatus, comprising: an etching chamber 1, a motion platform 2, a plasma torch 3, a gas supply assembly 4, and a microwave generator 5. The motion platform 2 is movably built into the etching chamber 1 for placing the material to be processed. The plasma torch 3 includes a nozzle 31, which is disposed relative to the motion platform 2 and connected to the inner wall of the etching chamber 1. The nozzle 31 is hollow inside and has a spray hole relative to the motion platform 2. The gas supply assembly 4 includes a first gas supply component 41, the outlet of which is connected to the inside of the nozzle 31 for providing plasma generating gas. The microwave generator 5 is connected to the nozzle 31 for providing microwave signals to the nozzle 31 to form a plasma flame.

[0030] In this device, the motion platform 2 is built into the etching chamber 1 and can move horizontally on its own plane to place materials. The ambient pressure inside the etching chamber 1 can be atmospheric pressure or negative vacuum. The nozzle 31 is set relative to the motion platform 2 and has an injection hole. The outlet end of the first gas supply component 41 is connected to the inside of the nozzle 31 to provide plasma generating gas. The microwave generator 5 is connected to the nozzle 31 to provide microwave signals to the nozzle 31 to cooperate in forming a plasma flame.

[0031] Compared to existing technologies, by replacing the radio frequency power supply with a microwave generator 5, the plasma generating gas is excited by the continuous introduction of microwave signals to form plasma in the cavity and is ejected at high speed through the injection hole of the nozzle 31. The ejected plasma torch can process the surface thickness of the quartz wafer, which helps to improve the surface uniformity. At the same time, since the formation of plasma does not require positive and negative electrodes, no bias voltage is generated. This can solve the technical problem in existing technologies where bias voltage is easily generated due to the need for positive and negative electrode discharge during plasma formation, resulting in electrostatic discharge loss.

[0032] Furthermore, the ambient pressure inside the etching chamber 1 in this device is atmospheric pressure or negative vacuum, and the device should also include a negative vacuum device. The air inlet of the negative vacuum device is connected to the interior of the etching chamber 1, and is used to discharge the exhaust gas generated in the etching chamber 1 during processing or to evacuate the etching chamber 1 into a vacuum. Specifically, the microwave generator 5 in this device can generate microwave signals and transmit the generated microwaves to the nozzle 31. Here, the etching chamber 1, the negative vacuum device, and the microwave generator 5 are all common and readily available equipment on the market, and are conventional settings known to those skilled in the art. They will not be described in detail here.

[0033] Furthermore, in this device, the motion platform 2 is movably connected to the etching chamber 1 through a drive component. Driven by the drive component, the material to be processed can be translated within the plane of the motion platform 2, thereby continuously adjusting the processing position.

[0034] like Figure 2 As shown, the side wall of the nozzle 31 is provided with an air inlet that communicates with the cavity. The plasma torch 3 also includes a quartz tube 32 and a coaxial electrode 33. The quartz tube 32 is built into the cavity, and the center line of the quartz tube 32 is coaxially arranged with the jet hole. An air inlet gap is formed between the outer wall of the quartz tube 32 and the inner wall of the cavity. The air inlet gap is connected with the air inlet. The outer wall of the quartz tube 32 is provided with at least one connecting hole, which is connected to both the air inlet gap and the inner hole of the quartz tube 32. The coaxial electrode 33 is built into the inner hole of the quartz tube 32 and is coaxially arranged with the jet hole.

[0035] Specifically, in this device, the inert gas is excited to generate plasma by the coaxially arranged quartz tube 32 and coaxial electrode 33 under the action of microwave signal. The principle of microwave excitation to generate plasma is a conventional setup known to those skilled in the art, and will not be elaborated further here.

[0036] The plasma generating gas enters the air inlet gap through the air inlet hole, then enters the interior of the quartz tube 32 through the connecting hole, and comes into contact with the coaxial electrode 33.

[0037] One implementation method is, for example Figure 2 As shown, there are multiple connecting holes, which are evenly distributed along the circumference of the quartz tube 32.

[0038] Multiple connecting holes evenly arranged along the circumference of the quartz tube 32 facilitate the introduction of gas into the quartz tube 32, improve the uniformity of gas introduction, and enhance the stability of device operation.

[0039] As another implementation method, such as Figure 2 As shown, the coaxial electrode 33 is spiral-shaped, and the plasma torch 3 also includes a connecting bracket 34. One end of the connecting bracket 34 is connected to the nozzle 31, and the other end is inserted into the inner hole of the quartz tube 32. The coaxial electrode 33 is sleeved on the connecting bracket 34.

[0040] The connecting bracket 34 connects and supports the coaxial electrode 33, while the spiral-shaped coaxial electrode 33 is used to improve the stability of the device operation.

[0041] like Figure 1 , Figure 2As shown, the first gas supply component 41 includes three first gas cylinders 411 and a first mixing chamber 412. The three first gas cylinders 411 are arranged in parallel to provide oxygen, carbon tetrafluoride gas or sulfur hexafluoride gas, and argon or helium gas respectively. The inlet end of the first mixing chamber 412 is connected to the outlet end of the three first gas cylinders 411, and the outlet end of the first mixing chamber 412 is connected to the inlet port.

[0042] The first mixing chamber 412 is used to fully mix the gas and then supply it to the nozzle 31 to improve the stability of the device operation.

[0043] like Figure 2 As shown, the bottom of the nozzle 31 has a protrusion 311 relative to the moving platform 2, and the injection hole passes through the protrusion 311.

[0044] The protrusion 311 helps to increase the energy of the plasma flame, improve the etching effect, and enhance the stability of the device.

[0045] One implementation method is, for example Figure 2 As shown, the protrusion 311 has an annular cavity, which is coaxially arranged with the injection hole and connected to the injection hole. The outer wall of the protrusion 311 has an auxiliary air hole, which is connected to the annular cavity. The air supply assembly 4 also includes a second air supply component 42, the outlet of which is connected to the auxiliary air hole for providing supplementary gas.

[0046] The second gas supply component 42 is provided to form gas compensation at the injection end of the nozzle 31, which is beneficial to improve the stability of the plasma flame. At the same time, compared with using the first gas supply component 41 for gas compensation, it can reduce gas waste and improve the compensation effect.

[0047] One implementation method is, for example Figure 1 As shown, the second gas supply unit 42 includes two second gas cylinders 421, which are arranged side by side, and the outlets of the two second gas cylinders 421 are respectively connected to the annular cavity to replenish carbon tetrafluoride gas or sulfur hexafluoride gas, argon gas or helium gas.

[0048] The setup of two second gas cylinders 421 can effectively compensate for the presence of either carbon tetrafluoride or sulfur hexafluoride, or either argon or helium as inert gases.

[0049] As another implementation method, such as Figure 1 As shown, the second air supply component 42 also includes a second mixing chamber 422, the air inlet of the second mixing chamber 422 is connected to the air outlet of the two second gas cylinders 421, and the air outlet of the second mixing chamber 422 is connected to an auxiliary air hole.

[0050] The second mixing chamber 422 is used to fully mix the gas and then supply it to the nozzle 31 to improve the stability of the device operation.

[0051] The present invention also provides a microwave plasma etching method, which utilizes the microwave plasma etching apparatus as described above, and includes the following steps:

[0052] S1. Place the quartz wafer to be processed on the motion platform 2;

[0053] S2. Open the three first gas cylinders 411 and introduce the mixed gas into the first mixing chamber 412 according to the gas supply volume ratio of oxygen: carbon tetrafluoride gas or sulfur hexafluoride gas: argon or helium = 0.01~0.1: 0.01~0.2: 2~5. After the mixture is evenly mixed, introduce it into the gas inlet gap.

[0054] S3. Start the microwave generator 5 and form plasma in the nozzle 31, and make the plasma eject plasma flame through the injection hole to form an etching process on the surface of the quartz wafer.

[0055] S4. Open the two second gas cylinders 421 to replenish carbon tetrafluoride gas or sulfur hexafluoride gas, argon or helium gas into the nozzle 31 to form a stable plasma flame.

[0056] Furthermore, this device should also include a detection device and a control device. The detection device scans the thickness of the quartz wafer to be processed, and the control device plans the motion path and trend of the motion platform 2. By working together, the thickness processing of the quartz wafer is completed, ensuring the consistency and uniformity of the quartz wafer thickness processing. Specifically, a white light interferometer is used to measure the thickness value at each point on the surface of the quartz wafer, and the above thickness value is fitted into a thickness distribution surface using Gaussian or other functions. Then, based on the above thickness distribution surface, the plasma etching time at each point on the surface of the quartz wafer is obtained using a deconvolution algorithm, and a plasma scanning processing route is generated. After the processing is completed, a white light interferometer is used to measure the thickness value at each point on the surface of the etched quartz wafer, and the thickness uniformity of the quartz wafer is calculated. Further details are omitted here.

[0057] In the specific workflow of this invention, the motion platform 2 is built into the etching chamber 1 and can move horizontally within its own plane to place materials. The ambient pressure inside the etching chamber 1 can be atmospheric pressure or negative vacuum. The nozzle 31 is positioned relative to the motion platform 2 and has injection holes. The outlet end of the first gas supply component 41 is connected to the interior of the nozzle 31 to provide plasma generating gas. The microwave generator 5 is connected to the nozzle 31 to provide microwave signals to the nozzle 31 to cooperate in forming a plasma flame. Compared with the prior art, by using the microwave generator 5 instead of the radio frequency power supply, as the plasma generating gas is continuously introduced, the microwave signal excites the plasma generating gas to form plasma in the cavity, which is then ejected at high speed from the injection holes of the nozzle 31. The ejected plasma torch can process the surface thickness of the quartz wafer, which helps to improve surface uniformity. At the same time, since the formation of plasma does not require positive and negative electrodes, no bias voltage is generated.

[0058] In operation, the quartz wafer to be processed is first placed on the motion platform 2; the three first gas cylinders 411 are opened, and the mixed gas is introduced into the first mixing chamber 412 according to the gas supply volume ratio of oxygen: carbon tetrafluoride or sulfur hexafluoride: argon or helium = 0.01~0.1: 0.01~0.2: 2~5. After the mixture is evenly mixed, it is introduced into the gas inlet gap; the microwave generator 5 is started, and plasma is formed in the nozzle 31, and the plasma is ejected through the jet hole to form a plasma flame to form an etching process on the surface of the quartz wafer; the two second gas cylinders 421 are opened, and the supplemented carbon tetrafluoride or sulfur hexafluoride, argon or helium are introduced into the nozzle 31 to form a stable plasma flame.

[0059] This device, through the aforementioned structure, can solve the technical problem in the prior art where bias voltage is easily generated due to the need for positive and negative electrode discharge during plasma formation, leading to electrostatic discharge loss.

[0060] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A microwave plasma etching apparatus, characterized by comprising: include: Etching chamber; A motion platform, which is movably built into the etching chamber, is used to hold the material to be processed; A plasma torch includes a nozzle, which is disposed relative to the motion platform and connected to the inner wall of the etching chamber. The nozzle is hollow to form a cavity, and the nozzle has a spray hole relative to the motion platform. The gas supply assembly includes a first gas supply component, the outlet of which is connected to the interior of the nozzle for supplying plasma generating gas; A microwave generator, connected to the nozzle, is used to provide microwave signals to the nozzle to form a plasma flame; The nozzle has an air inlet hole on its side wall that communicates with the cavity. The plasma torch also includes a quartz tube and a coaxial electrode. The coaxial electrode is built into the inner hole of the quartz tube and is coaxially arranged with the jet hole. The microwave generator is electrically connected to the coaxial electrode. The quartz tube is built into the cavity and coaxially sleeved on the coaxial electrode. An air inlet gap is formed between the outer wall of the quartz tube and the inner wall of the cavity. The outer wall of the quartz tube has multiple connecting holes, which are evenly distributed along the circumference of the quartz tube. The air inlet gap is connected to the air inlet holes and the multiple connecting holes. The nozzle has a protrusion at its bottom relative to the moving platform, and the injection hole penetrates the protrusion.

2. The microwave plasma etching apparatus according to claim 1, characterized in that, The coaxial electrode is spiral-shaped, and the plasma torch also includes a connecting bracket. One end of the connecting bracket is connected to the nozzle, and the other end is inserted into the inner hole of the quartz tube. The coaxial electrode is sleeved on the connecting bracket.

3. The microwave plasma etching apparatus according to claim 2, characterized in that, The first gas supply unit includes three first gas cylinders and a first mixing chamber. The three first gas cylinders are arranged in parallel to provide oxygen, carbon tetrafluoride gas or sulfur hexafluoride gas, and argon or helium gas respectively. The inlet end of the first mixing chamber is connected to the outlet end of each of the three first gas cylinders, and the outlet end of the first mixing chamber is connected to the inlet port.

4. The microwave plasma etching apparatus according to claim 3, characterized in that, The protrusion has an annular cavity, which is coaxially arranged with and communicates with the injection hole. The outer wall of the protrusion has an auxiliary air hole, which is communicated with the annular cavity. The air supply assembly also includes a second air supply component, the outlet of which is communicated with the auxiliary air hole for providing supplementary gas.

5. The microwave plasma etching apparatus according to claim 4, characterized in that, The second gas supply unit includes two second gas cylinders arranged side by side, and the outlets of the two second gas cylinders are respectively connected to the annular cavity for replenishing carbon tetrafluoride gas or sulfur hexafluoride gas, argon gas or helium gas.

6. The microwave plasma etching apparatus according to claim 5, characterized in that, The second gas supply component also includes a second mixing chamber, the inlet of which is connected to the outlet of the two second gas cylinders, and the outlet of which is connected to the auxiliary air hole.

7. A microwave plasma etching method, characterized in that, The method employs the microwave plasma etching apparatus as described in any one of claims 1 to 6, comprising the following steps: S1. Place the quartz wafer to be processed on the motion platform; S2. Open the three first gas cylinders and introduce the mixed gas into the first mixing chamber according to the gas supply volume ratio of oxygen: carbon tetrafluoride gas or sulfur hexafluoride gas: argon or helium = 0.01~0.1: 0.01~0.2: 2~5. After the mixture is evenly mixed, introduce it into the inlet gap. S3. Start the microwave generator and form plasma in the nozzle, and make the plasma ejected through the injection hole to form an etching process on the surface of the quartz wafer. S4. Open the two second gas cylinders and introduce the replenished carbon tetrafluoride or sulfur hexafluoride, argon or helium gas into the nozzle to form a stable plasma flame.

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