Wafer chamfering processing method, processing device and system

Abstract

The invention discloses a wafer chamfering machining method, device and system, and the method comprises the steps: providing a to-be-machined wafer, a counter electrode and a flexible adjustable auxiliary electrode, and enabling the to-be-machined wafer and the counter electrode to be connected with the positive electrode and the negative electrode of a power supply respectively; placing a wafer to be processed in the electrolyte opposite to the counter electrode and the flexible adjustable counter electrode at intervals; the preset shape of the auxiliary electrode is obtained through electric field simulation according to the target chamfer of the wafer to be machined, and the flexible adjustable auxiliary electrode is set to be in the preset shape; voltage is applied through a power supply, electrolytic plasmas are generated on the surface of the edge of the to-be-processed wafer, the surface of the area is subjected to an oxidation reaction under the action of the electrolytic plasmas, and the oxidized wafer and the electrolyte are subjected to a chemical reaction to be removed. According to the method, the non-contact machining technology is adopted, mechanical stress and surface damage in the machining process are avoided, the plasma has extremely high energy density, rapid machining can be achieved, and the machined surface is smooth and free of microcracks.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer processing, and in particular, to a wafer chamfering processing method, processing apparatus and system. Background Art

[0002] In the process of semiconductor manufacturing, wafer edge treatment is mainly to prevent the wafer edge from cracking, prevent thermal stress concentration, and increase the flatness of the epitaxial layer and photoresist layer at the wafer edge. This process is an important and challenging link. Microcracks, burrs and other defects are likely to occur at the wafer edge. These defects not only affect the mechanical strength of the wafer, but may also cause particle contamination in the subsequent production process, thereby affecting the yield and reliability of the chip. How to achieve wafer chamfering in a manner of low surface damage, high efficiency and environmental protection has long been a difficult problem in the field of wafer manufacturing.

[0003] Currently, the common process for wafer chamfering is mechanical grinding, but this method still has some drawbacks. First of all, edge chipping is one of the main problems. Due to the brittleness of materials such as silicon, microcracks and fractures will occur during the grinding process. These small defects may expand, resulting in serious damage or wafer breakage in the subsequent manufacturing stage. Secondly, the grinding process will also cause surface and internal damage. Factors such as temperature, applied force and strain rate will all affect this damage, thereby affecting the structural integrity and performance of the wafer. In addition, it is challenging to achieve a uniform edge profile. Variations during the grinding process may lead to uneven edges, affecting the performance of semiconductor devices. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. For this purpose, the present invention provides a wafer chamfering processing method, processing apparatus and system.

[0005] In the first aspect of the present invention, a wafer chamfering processing method is provided, including the following steps:

[0006] Provide a wafer to be processed, a counter electrode and a flexible adjustable auxiliary electrode;

[0007] Connect the wafer to be processed and the counter electrode to the positive and negative poles of a power supply respectively;

[0008] Place the wafer to be processed, the counter electrode and the flexible adjustable auxiliary electrode in an electrolyte; the wafer to be processed and the counter electrode are arranged opposite to each other at intervals, and the flexible adjustable auxiliary electrode is arranged opposite to the chamfering part to be processed on the wafer to be processed;

[0009] Obtain a predetermined shape of the auxiliary electrode through electric field simulation according to the target chamfer of the wafer to be processed, and set the flexible adjustable auxiliary electrode to the predetermined shape;

[0010] A voltage is applied through the power supply, and electrolytic plasma is generated on the edge surface of the wafer to be processed. The edge surface undergoes an oxidation reaction under the action of the electrolytic plasma, and the oxidized wafer undergoes a chemical reaction with the electrolyte and is removed.

[0011] The wafer chamfering method according to the embodiment of the present invention has at least the following beneficial effects: The wafer chamfering method uses a flexible and adjustable auxiliary electrode with a controllable shape. The positive and negative electrodes of the power supply are respectively connected to the wafer to be processed and the counter electrode. The wafer to be processed is disposed opposite to the counter electrode and the flexible and adjustable auxiliary electrode at intervals in the electrolyte, and the flexible and adjustable auxiliary electrode is controlled to face the chamfering part to be processed on the wafer to be processed. According to the target chamfer of the wafer to be processed, the predetermined shape of the auxiliary electrode is obtained through electric field simulation, and the flexible and adjustable auxiliary electrode is set to this predetermined shape. Then, a voltage is applied through the power supply, and electrolytic plasma is generated on the edge surface of the wafer to be processed. Under the action of the electrolytic plasma, thermal oxidation occurs on the edge surface of the wafer to be processed, and the oxidized wafer undergoes a chemical reaction with the electrolyte, thereby realizing the chamfering processing of the wafer. Specifically, after the voltage is applied, the local electrolyte near the wafer to be processed is heated and evaporated to form an air film on the surface of the wafer to be processed. The air film at the edge of the wafer is thinner and discharges preferentially. After the air film is electrically broken down, a plasma channel is formed, and anode plasma is generated on the surface at the edge of the wafer to be processed. The plasma in the plasma channel with high energy and high activity (such as ·OH - 、O - 、O2、H and other high-energy electrons and active particles) bombards the surface at the edge of the wafer to be processed to generate local high-temperature regions (suddenly heated surfaces). These high-temperature regions promote chemical reactions (specifically, thermal oxidation reactions), so that the material on the wafer surface is oxidized. The oxidized material on the wafer surface can further undergo a chemical reaction with the electrolyte to be further removed, and the processed surface is smooth and free of microcracks. Among them, based on the target chamfer of the wafer to be processed, the predetermined shape of the auxiliary electrode is obtained through electric field simulation, and by adjusting the flexible and adjustable auxiliary electrode to this predetermined shape, it can be ensured that the target chamfer is machined on the edge of the wafer to be processed. The above processing method adopts a non-contact processing technology, which not only avoids mechanical stress and surface damage during the processing, but also the plasma has an extremely high energy density and can quickly remove the workpiece material, greatly improving the processing efficiency and saving time, making the material removal faster and more efficient, and the processed surface is smooth and free of microcracks.

[0012] In some embodiments of the present invention, the concentration of the electrolyte is 1 wt% to 10 wt%. Further, the concentration of the electrolyte can be 1% to 8%, 3% to 7%, 4 wt% to 8 wt%, 4 wt% to 6 wt%, 7% to 9% or 5 wt% to 10 wt%.

[0013] By controlling the concentration of the electrolyte within the above concentration range, chamfer machining can be effectively achieved. If the electrolyte concentration is too high, an oxide film will form on the surface of the wafer to be machined, deteriorating the surface topography of the wafer. As the electrolyte concentration increases, the density, surface tension, kinematic viscosity, and conductivity coefficient increase, while the contact angle and thermal conductivity coefficient show a downward trend. Specifically, referring to the relationship between the characteristics of liquid molecules and the electrolyte concentration, when the solution concentration decreases, these characteristics will change favorably. On the contrary, when the concentration is too high, the critical heat flux q value is higher, and the film boiling state may not occur, making it impossible to achieve uniform material removal.

[0014] The relationship between the characteristics of liquid molecules and the electrolyte concentration, or the specific calculation formula for the critical heat flux q is as follows:

[0015]

[0016] Among them, q is the critical heat flux, λ is the thermal conductivity of the liquid, ρ is the liquid density, ρ′ is the vapor density, σ is the surface tension coefficient, T is the boiling point of the liquid, and v is the kinematic viscosity of the liquid.

[0017] In some embodiments of the present invention, the components of the electrolyte include sodium hydroxide and a solvent.

[0018] In some embodiments of the present invention, the components of the electrolyte further include a surfactant.

[0019] In some embodiments of the present invention, the content of sodium hydroxide in the electrolyte is 1 wt% - 15 wt%, 4 wt% - 8 wt%, 5 wt% - 10 wt%, or 6 wt% - 12 wt%.

[0020] According to the target chamfer of the wafer to be machined, the predetermined shape of the auxiliary electrode is obtained through electric field simulation. Specifically, it may include: first setting the initial shape of the auxiliary electrode, then simulating the electric field between the auxiliary electrode and the anode (i.e., the wafer to be machined), and then the shape change (i.e., material removal) of the anode under this electric field can be obtained. If too much material is removed in a certain area, the corresponding part of the auxiliary electrode is adjusted to be farther away, and vice versa, the corresponding part of the auxiliary electrode is made closer. Through continuous iterative optimization in this way, the final shape of the auxiliary electrode can be obtained. In the above simulation process, generally, the electric field strength is greater and the material removal rate is also greater where the distance between the auxiliary electrode and the wafer to be machined is smaller, and vice versa, the removal rate is smaller. By controlling the distance between the auxiliary electrode and different positions on the wafer to be machined, the material removal rate at the corresponding positions of the wafer can be regulated, thereby machining a chamfer with a specific shape.

[0021] In some embodiments of the present invention, the voltage is 190V - 250V. Further, the voltage can be 200V - 250V or 210V - 230V.

[0022] In some embodiments of the present invention, the voltage is a DC voltage.

[0023] The inventors found through experimental research that during the chamfering process, the oxidation intensity of the electrolytic plasma and the chemical reaction removal rate of the oxidized wafer and the electrolyte are mainly determined by the electric field strength. If the voltage is too low, the activation energy provided is insufficient, that is, the removal rate of the oxidized wafer is greater than the wafer oxidation generation rate; while if the voltage is too high, sufficient activation energy is provided, the removal rate of the oxidized wafer cannot increase, but the wafer oxidation ability continues to improve, showing that the removal rate of the oxidized wafer is less than the wafer oxidation generation rate. Therefore, whether the voltage is too high or too low, it is difficult to achieve uniform material removal. In the above method, under the condition that the electrolyte concentration is 1wt% - 15wt%, a DC voltage of 190V - 250V is used during the chamfering process, which can make the removal rate of the oxidized wafer equal to the wafer oxidation generation rate, and can achieve uniform material removal, thereby realizing stable chamfering processing.

[0024] In some embodiments of the present invention, the wafer to be processed is a silicon carbide wafer. The silicon carbide wafer may include a first surface and a second surface disposed opposite to each other. The first surface is a silicon surface, and the second surface is a carbon surface.

[0025] For the silicon carbide wafer, using the above wafer chamfering processing method, after applying voltage, electrolytic plasma is generated on the surface of the wafer to be processed. The plasma undergoes a thermal oxidation reaction with the wafer to be processed. The silicon element in SiC is oxidized into silicon dioxide (SiO2), and the carbon element is oxidized into carbon dioxide (CO2). Then, the oxidized wafer undergoes a chemical reaction with sodium hydroxide (NaOH) in the electrolyte to achieve material removal.

[0026] In some embodiments of the present invention, the target chamfer of the wafer to be processed is a T-shaped chamfer or an R-shaped chamfer.

[0027] In a second aspect of the present invention, a wafer chamfering processing device is proposed, including:

[0028] A receiving groove for receiving the electrolyte;

[0029] A power supply having a positive electrode and a negative electrode, the positive electrode being used to connect to the wafer to be processed;

[0030] A counter electrode connected to the negative electrode;

[0031] A flexible adjustable auxiliary electrode configured to be placed in the electrolyte received in the receiving groove in cooperation with the wafer to be processed and the counter electrode, and spaced relatively from the chamfering part to be processed on the wafer to be processed for chamfering processing.

[0032] The above wafer chamfering processing device can be used to implement the foregoing wafer chamfering processing method, that is, the device can be used as a wafer chamfering processing device for implementing the foregoing wafer chamfering processing method; correspondingly, the foregoing processing method can be realized by this device, that is, the wafer chamfer is processed by using this device. During specific processing, electrolyte can be injected into the accommodation groove, the wafer to be processed is connected to the positive electrode of the power supply, and it is controlled that the wafer to be processed is spaced relatively from the counter electrode and the flexible adjustable auxiliary electrode respectively in the electrolyte, and the flexible adjustable auxiliary electrode is arranged opposite to the chamfering part to be processed on the wafer to be processed. According to the target chamfer of the wafer to be processed, the predetermined shape of the auxiliary electrode is obtained through electric field simulation, and then the flexible adjustable auxiliary electrode is set to the predetermined shape. A voltage is applied through the power supply, and a gas film is formed on the surface of the wafer to be processed due to the heating and evaporation of the nearby electrolyte. The gas film at the edge of the wafer is thinner and will discharge preferentially. After the gas film is broken down, anode plasma will be generated on the surface of the wafer to be processed. Furthermore, the activity of the plasma can be used to promote the plasma thermal oxidation of the wafer, and then under the high temperature and high pressure environment provided by the plasma, a chemical reaction occurs between the electrolyte and the oxidized wafer to achieve the removal of the edge material.

[0033] In some embodiments of the present invention, the flexible adjustable auxiliary electrode includes a flexible electrode and a driving component; the flexible electrode is configured to be placed in the electrolyte accommodated in the accommodation groove in cooperation with the wafer to be processed and the counter electrode, and is spaced relatively from the chamfering part to be processed on the wafer to be processed for chamfering processing; the driving component is used to adjust the shape of the flexible electrode.

[0034] In some embodiments of the present invention, the driving component includes:

[0035] An actuator, the actuator is connected to the flexible electrode;

[0036] An actuator controller, the actuator controller is communicatively connected to the actuator, and is used to control the actuator to adjust the shape of the flexible electrode.

[0037] In some embodiments of the present invention, a number of connecting cable nodes are uniformly arranged on the flexible electrode, and the actuator is connected to the connecting cable nodes through a cable.

[0038] In some embodiments of the present invention, the wafer chamfering processing device further includes:

[0039] An installation component, the installation component includes an installation frame, and a first fixing member and a second fixing member provided on the installation frame. The first fixing member is provided above the accommodation groove and is used to fix the counter electrode; the second fixing member is arranged opposite to the first fixing member and is provided above the accommodation groove inside, and is used to fix the wafer to be processed.

[0040] In some embodiments of the present invention, the second fixing member is slidably connected to the mounting bracket and configured to move in a direction approaching or departing from the flexible adjustable auxiliary electrode.

[0041] In some embodiments of the present invention, the wafer chamfering processing device further includes a lifting mechanism disposed below the accommodating groove for controlling the lifting of the accommodating groove.

[0042] In a third aspect of the present invention, a wafer chamfering processing system is proposed, including any one of the foregoing wafer processing devices; and further including at least one of an electrolyte circulation device, a monitoring device, and a gas recovery device;

[0043] Wherein, the electrolyte circulation device includes a liquid storage tank, a circulation pipeline, and a filter; the liquid storage tank is connected to the accommodating groove for storing electrolyte and providing electrolyte for the accommodating groove; the filter is disposed between the accommodating groove and the liquid storage tank and is respectively connected to the accommodating groove and the liquid storage tank through the circulation pipeline;

[0044] The monitoring device is disposed in the accommodating groove, and the monitoring device is selected from at least one of a temperature sensor, a conductivity sensor, a pH electrode, and a hydrogen sensor;

[0045] The gas recovery device is used for collecting the gas generated by the processing reaction in the accommodating groove. Description of the Drawings

[0046] The present invention will be further described below with reference to the drawings and embodiments, wherein:

[0047] Figure 1 is a schematic structural diagram of an embodiment of the wafer chamfering processing device of the present invention;

[0048] Figure 2 is Figure 1 a schematic structural diagram of the flexible adjustable auxiliary electrode in the wafer chamfering processing device shown;

[0049] Figure 3 is Figure 2 a schematic structural diagram of the flexible electrode in the flexible adjustable auxiliary electrode shown;

[0050] Figure 4 is a schematic structural diagram of an embodiment of the wafer chamfering processing system of the present invention;

[0051] Figure 5 is a schematic diagram of the target T-shaped chamfer structure of the wafer chamfering processing in Embodiment 3;

[0052] Figure 6 is a schematic process flow diagram of the wafer chamfering processing method in Embodiment 3;

[0053] Figure 7 Schematic diagram of the wafer chamfering processing system in Embodiment 3;

[0054] Figure 8 Working principle diagram of the wafer chamfering processing method in Embodiment 3;

[0055] Figure 9 Confocal laser images of the wafer to be processed before and after chamfering in Embodiment 3;

[0056] Figure 10 Schematic diagram of the target R-shaped chamfer structure for wafer chamfering in Embodiment 4;

[0057] Figure 11 Process flow schematic diagram of the wafer chamfering processing method in Embodiment 4. Detailed implementation manners

[0058] The concept of the present invention and the technical effects generated will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present invention.

[0059] Embodiment 1

[0060] This embodiment proposes a wafer chamfering processing device, and its structural schematic diagram is as shown in Figure 1 shown, including a receiving groove 11, a power supply, a counter electrode 15 and a flexible adjustable auxiliary electrode 12. Among them, the receiving groove 11 is used to hold the electrolyte; the power supply has a positive electrode and a negative electrode, the positive electrode is used to connect with the wafer to be processed, and the negative electrode is connected with the counter electrode 15; the flexible adjustable auxiliary electrode 12 is configured to cooperate with the wafer to be processed and the counter electrode 15 and be placed in the electrolyte held by the receiving groove 11 for chamfering processing.

[0061] Among them, the receiving groove 11 serves as the working area for wafer chamfering processing and is used to hold the working medium electrolyte. The material of the receiving groove 11 generally adopts an insulating material, and its shape is not limited and can be a cylindrical shape, a square column shape, etc. In order to facilitate observing the processing reaction situation in the receiving groove 11, the receiving groove 11 can adopt a transparent insulating material, or an observation window can be provided on the side of the receiving groove 11.

[0062] The power supply can specifically adopt a DC power supply. The positive electrode and the negative electrode of the power supply are respectively connected with the wafer to be processed and the counter electrode 15. During use, through the cooperation of the wafer to be processed, the counter electrode 15 and the flexible adjustable auxiliary electrode 12, the three electrodes are placed in the electrolyte working medium for wafer chamfering processing.

[0063] The counter electrode 15 is configured to cooperate with the wafer to be processed, and is disposed opposite and spaced apart in the electrolyte accommodated in the accommodation groove 11 for chamfering processing. Specifically, the counter electrode 15 is configured to be placed in the electrolyte accommodated in the accommodation groove 11 in cooperation with the wafer to be processed and the flexible adjustable auxiliary electrode 12, and is disposed opposite and spaced apart from the wafer to be processed for chamfering processing. The material of the counter electrode 15 can be a metal conductive material.

[0064] The auxiliary electrode uses the flexible adjustable auxiliary electrode 12, which is specifically disposed in the accommodation groove 11 and is configured to be placed in the electrolyte accommodated in the accommodation groove 11 in cooperation with the wafer to be processed and the counter electrode during chamfering processing, and is disposed opposite and spaced apart from the chamfering part to be processed on the wafer to be processed for chamfering processing. On this basis, the specific setting position of the flexible adjustable auxiliary electrode 12 can be adjusted according to the actual situation. For example, the flexible adjustable auxiliary electrode 12 can be configured to be below the wafer to be processed and is disposed opposite and spaced apart from the wafer to be processed; if the wafer to be processed is completely immersed in the electrolyte during the processing, the flexible adjustable auxiliary electrode 12 can also be controlled to be above the wafer to be processed and is disposed opposite and spaced apart from the wafer to be processed.

[0065] During use, based on the flexibility and structure adjustable characteristics of the auxiliary electrode, after obtaining a predetermined shape through electric field simulation according to the target chamfer of the wafer to be processed, the shape of the flexible adjustable auxiliary electrode 12 can be correspondingly adjusted. And during the chamfering processing, the flexible adjustable auxiliary electrode 12 does not need to be powered on, but only needs to be placed in the electrolyte, and is controlled to be disposed opposite and spaced apart from the chamfering part to be processed on the wafer to be processed. This auxiliary electrode only plays an electric field constraint role and does not participate in the discharge circuit, but mainly relies on the electric field concentration effect, that is, the place where the distance between the auxiliary electrode and the wafer to be processed is small discharges preferentially to achieve the processing of chamfers of any shape. Thus, by controlling the distance between the auxiliary electrode and different positions on the wafer to be processed, the material removal rate of the corresponding positions of the wafer can be regulated, so as to process chamfers of a specific shape.

[0066] See Figure 2 and Figure 3 , in some embodiments, the flexible adjustable auxiliary electrode 12 can be designed to include a flexible electrode 121 and a driving component. The driving component is used to regulate the shape of the flexible electrode 121. The flexible electrode 121 is configured to be placed in the electrolyte accommodated in the accommodation groove 11 in cooperation with the wafer to be processed and the counter electrode, and is disposed opposite and spaced apart from the chamfering part to be processed on the wafer to be processed for chamfering processing. Specifically, the driving component can include an actuator 122 and an actuator controller 123. The actuator 122 is connected to the flexible electrode 121, and the actuator controller 123 is communicatively connected to the actuator 122 for controlling the actuator 122 to regulate the shape of the flexible electrode 121. Among them, the actuator 122 can be designed as several, such as 2, 3, 5, 6, 8, etc., and each actuator 122 is evenly connected to the flexible electrode 121.

[0067] Further, in some embodiments, a plurality of connecting cable nodes 124 are uniformly arranged on the flexible electrode 121, and the actuator 122 is connected to each connecting cable node 124 through a cable 125. The flexible electrode 121 can be specifically designed to include a plurality of electrode plates 121' connected in a uniform arrangement, and connecting cable nodes 124 are arranged between at least some of the connected electrode plates 121'. Through the above structural arrangement of the flexible adjustable auxiliary electrode 12, during use, the actuator controller 123 can send instructions to each actuator 122 through an electrical signal, precisely control the positions and angles of each position of the flexible electrode 121. By adjusting the expansion and contraction of the cable 125, the flexible electrode 121 can be adjusted to a predetermined shape to meet the requirements of target chamfering processing.

[0068] To facilitate processing and improve the structural stability of the device, the wafer chamfering processing device may further include a mounting assembly 13. The mounting assembly includes a mounting frame 131, and a first fixing member 132 and a second fixing member 133 provided on the mounting frame 131. The first fixing member 132 is provided above the accommodating groove 11 for fixing the counter electrode 15, and the second fixing member 133 is arranged opposite to the first fixing member 132 and is provided above the accommodating groove 11 for fixing the wafer to be processed.

[0069] In this embodiment, the first fixing member 132 is a fixture, and the second fixing member 133 includes a connecting member and a vacuum chuck. The first fixing member 132 has electrical conductivity. One end of the first fixing member 132 close to the accommodating groove 11 is used to clamp and fix the counter electrode 15, and the end far from the accommodating groove 11 is connected to the negative pole of the power supply; in the second fixing member 133, the vacuum chuck is fixed to the mounting frame 131 through the connecting member, and the vacuum chuck is connected to one end of the connecting member close to the accommodating groove 11 for adsorbing and fixing the wafer to be processed; the connecting member includes a conductive connecting portion. One end of the conductive connecting portion is used to conductively connect with the wafer to be processed, and the other end far from the accommodating groove 11 is connected to the positive pole of the power supply. Thus, during use, the counter electrode 15 and the wafer to be processed can be respectively connected to the negative pole and the positive pole of the power supply through the conductive connecting portions on the first fixing member 132 and the second fixing member 133. Specifically, the power supply may include a positive pole clip 141 connected to the positive pole of the power supply and a negative pole clip 142 connected to the negative pole of the power supply. The positive pole clip 141 is clamped and connected to one end of the conductive connecting portion far from the accommodating groove 11, and the negative pole clip 142 is clamped and connected to one end of the first fixing member 132 far from the accommodating groove 11.

[0070] In other embodiments, the first fixing member 132 may also be made of an insulating material and is only used for mounting and fixing the counter electrode 15. The counter electrode 15 is connected to the negative pole of the power supply through an additional conductive connecting member. The second fixing member 133 for fixing the wafer to be processed may also adopt a structural arrangement similar to that of the first fixing member 132.

[0071] Furthermore, in order to improve the flexibility of the device, the second fixing member 133 can be designed to be slidably connected to the mounting bracket 131 and configured to move in a direction close to or away from the flexibly adjustable auxiliary electrode 12, so as to facilitate the installation of the wafer to be processed and the initial distance between the two electrodes. Alternatively, the flexibly adjustable auxiliary electrode 12 can be movably arranged in the accommodation groove 11 and specifically configured to move in a direction close to or away from the wafer to be processed.

[0072] In some embodiments, the mounting bracket 131 can be designed as a mounting housing 131' with a receiving cavity. The accommodation groove 11 is arranged in the receiving cavity of the mounting housing 131'. A working window 134 is provided on the side of the mounting housing 131' for the staff to perform the wafer chamfering processing operation; a fixture mounting through-hole 135 is provided on the top of the mounting housing 131'. The first fixing member 132 and the second fixing member 133 are installed on the top of the mounting housing 131' and inserted into the accommodation groove 11 in the receiving cavity of the mounting housing 131' through the mounting through-hole 135. Through the above design of the mounting housing 131', the main processing environment for wafer chamfering is basically delimited within the receiving cavity of the mounting housing 131', which can improve the cleanliness of the working environment.

[0073] In this embodiment, the wafer chamfering device further includes a lifting mechanism 15. The lifting mechanism 15 is arranged below the accommodation groove 11 and is used to control the lifting of the accommodation groove 11. Specifically, during processing, the up and down movement of the lifting mechanism 15 can be used to control the wafer to be processed and the counter electrode 15 to be immersed in the electrolyte and to adjust the immersion depth of the electrodes in the electrolyte.

[0074] In some embodiments, the mounting bracket 131 can also be designed as a lifting bracket. The first fixing member 132 and the second fixing member 133 are installed on the lifting bracket. The lifting bracket is configured to mount the first fixing member 132 and the second fixing member 133 and control the first fixing member 132 and the second fixing member 133 to move in a direction close to or away from the accommodation groove 11. Furthermore, during use, the up and down movement of the installed lifting bracket can also be used to control the wafer to be processed and the counter electrode 15 to be immersed in the electrolyte and to adjust the immersion depth of the electrodes in the electrolyte.

[0075] When chamfering the wafer using the above wafer chamfering processing device, electrolyte can be injected into the accommodation groove 11 first. The counter electrode 15 and the wafer to be processed are respectively connected to the negative and positive electrodes of the power supply, and the wafer to be processed is arranged at intervals relative to the counter electrode 15 and the flexible adjustable auxiliary electrode 12 and immersed in the electrolyte. The flexible adjustable auxiliary electrode 12 is arranged opposite to the chamfering part to be processed on the wafer to be processed. After obtaining the predetermined shape of the auxiliary electrode through electric field simulation according to the target chamfer of the wafer to be processed, the flexible adjustable auxiliary electrode 12 is set to the predetermined shape. A voltage is applied through the power supply, and plasma is preferentially generated on the surface of the edge position of the wafer to be processed. The surface of the edge of the wafer to be processed undergoes an oxidation reaction under the action of the plasma, and the oxidized wafer reacts chemically with the electrolyte and is removed, thereby realizing wafer chamfering processing.

[0076] Embodiment 2

[0077] This embodiment provides a wafer chamfering processing system, and its structural schematic diagram is as Figure 4 shown, including a wafer chamfering processing device 10, and also including an electrolyte circulation device 20, a monitoring device 30 and a gas recovery device 40. Among them, the wafer chamfering processing device can adopt Figures 1 to 3 the wafer chamfering processing device shown, and the specific structure will not be elaborated.

[0078] The electrolyte circulation device 20 includes a liquid storage tank 21, a circulation pipeline and a filter 22; the liquid storage tank 21 is connected to the accommodation groove in the wafer chamfering processing device 10 for storing electrolyte and providing electrolyte for the accommodation groove; the filter 22 is arranged between the accommodation groove and the liquid storage tank 21 and is respectively connected to the accommodation groove and the liquid storage tank 21 through the circulation pipeline. Thus, the electrolyte processed in the accommodation groove can be transported to the filter 22 through the circulation pipeline, and after being filtered by the filter 22, it flows back to the liquid storage tank 21, thereby realizing recycling, which can reduce resource waste and improve utilization rate.

[0079] In order to improve the reaction efficiency, the electrolyte circulation device 20 may further include an electrolyte heating device 23, and the electrolyte heating device is connected to the liquid storage tank 21. The electrolyte heating device 23 can adopt a steam generator to introduce the heated steam into the liquid storage tank 21 to realize heating of the electrolyte.

[0080] The monitoring device 30 is arranged in the accommodation groove, and the monitoring device is selected from at least one of a temperature sensor 31, a conductivity sensor 32, a pH electrode 33, and a hydrogen sensor 34. Through the setting of the above monitoring device 30, it is convenient to monitor the processing situation in the accommodation groove.

[0081] The gas recovery device 40 is used to collect the gas generated by the processing reaction in the containing tank. The gas recovery device 40 may include a suction fan 41 and a gas adsorption device 42. The suction fan 41 is configured to extract the gas generated by the reaction in the containing tank into the gas adsorption device 42 to adsorb and remove the gas.

[0082] In some embodiments of the wafer chamfering processing system, it can also be designed to include one or two of the electrolyte circulation device 20, the monitoring device 30, and the gas recovery device 40 in addition to the wafer chamfering processing device 10.

[0083] Embodiment 3

[0084] This embodiment proposes a wafer chamfering processing method, which is implemented by using the Figures 1 to 3 shown wafer processing device. The target chamfer for wafer chamfering is a T-shaped chamfer, specifically as Figure 5 shown, Figure 5 where T represents the total chamfer thickness; X1 represents the horizontal distance of the chamfer leading edge; X2 represents the horizontal distance of the chamfer trailing edge; Y1 represents the vertical distance of the upper part of the chamfer; Y2 represents the vertical distance of the lower part of the chamfer; Y3 represents the vertical distance of the middle part of the chamfer; R1 represents the upper fillet radius; R2 represents the lower fillet radius; A1 represents the upper chamfer angle; A2 represents the lower chamfer angle.

[0085] The process flow of this wafer chamfering processing method is as Figure 6 shown, including the following steps:

[0086] (1) As Figure 7 shown, build a wafer chamfering processing system, provide a wafer to be processed, connect the wafer to be processed to the positive electrode of the power supply, connect the counter electrode 15 to the negative electrode of the power supply, and inject electrolyte into the containing tank 11.

[0087] Among them, the wafer to be processed is a silicon carbide (SiC) wafer with two surfaces being a carbon surface (C surface) and a silicon surface (Si surface) respectively. Specifically, the wafer to be processed is adsorbed on the vacuum chuck at one end of the second fixing member 133 close to the containing tank 11. The counter electrode 15 is clamped on the first fixing member 132 at one end close to the containing tank 11. One end of the first fixing member 132 away from the containing tank 11 is electrically connected to the negative electrode of the power supply. One end of the conductive connecting member in the second fixing member 133 is connected to the wafer to be processed, and the end away from the containing tank 11 is connected to the positive electrode of the power supply. Thus, the wafer to be processed and the counter electrode 15 are respectively electrically connected to the positive and negative electrodes of the power supply through the conductive connecting member in the second fixing member 133 and the first fixing member 132. The electrolyte injected into the containing tank 11 contains sodium hydroxide, surfactant and solvent water. Among them, the content of sodium hydroxide is controlled to be 1wt% - 15wt%.

[0088] (2) Place the wafer to be processed opposite to the counter electrode 15 and the flexible adjustable auxiliary electrode 12 at intervals, and place them in the electrolyte. At the same time, control the flexible adjustable auxiliary electrode 12 to be opposite to the chamfering part of the wafer to be processed.

[0089] By controlling the second fixing member 133 to slide on the mounting frame 131, control the relative interval setting between the wafer to be processed and the flexible adjustable auxiliary electrode 12, and adjust the distance between the two, as Figure 6 shown in (a); control the accommodating groove 11 to move upward through the lifting mechanism 15 so that the wafer to be processed and the flexible electrode 121 are immersed in the electrolyte in the accommodating groove 11.

[0090] (3) According to the target chamfer of the wafer to be processed, obtain the predetermined shape of the auxiliary electrode through electric field simulation, and set the flexible adjustable auxiliary electrode 12 to the predetermined shape.

[0091] According to the target T-shaped chamfer of the wafer to be processed, obtain the predetermined shape of the auxiliary electrode through electric field simulation. The actuator controller 123 in the flexible adjustable auxiliary electrode 12 sends instructions to each actuator 122 through an electrical signal. The actuator 122 adjusts the pulling positions and angles on the flexible electrode 121 through the telescopic cable 125, so as to adjust the flexible electrode 121 to the predetermined shape obtained by simulation, as Figure 6 shown in (b).

[0092] (4) Apply a voltage through the power supply, and electrolytic plasma is generated on the edge surface of the wafer to be processed. The edge surface of the wafer to be processed undergoes an oxidation reaction under the action of the electrolytic plasma, and the oxidized part of the wafer reacts chemically with the electrolyte and is removed.

[0093] Among them, the upper half and the lower half of the wafer to be processed can be processed sequentially. Specifically, the lower half area can be immersed in the electrolyte for chamfering processing first. After the lower half area is processed, the wafer to be processed is rotated 180°, and the upper half area is immersed in the electrolyte for processing.

[0094] The processing process specifically uses a DC power supply to apply a DC voltage of 190V - 250V. The working principle diagram of applying voltage for wafer chamfering processing is as Figure 8 shown. Specifically, after the voltage is applied, the local electrolyte near the wafer to be processed is heated and evaporated to form a gas film on the surface of the wafer to be processed. The gas film at the edge of the wafer is thinner and discharges preferentially. After the gas film is broken down, a plasma channel is formed, and plasma is generated on the surface at the edge of the wafer to be processed. The plasma in the plasma channel has high energy and high activity (such as ·OH - 、O -High-energy electrons and active particles such as O2 and H bombard the surface of the wafer, generating local high-temperature regions (suddenly heated surfaces). These high-temperature regions promote the thermal oxidation reaction between the plasma and the wafer. The silicon element in SiC is oxidized to silicon dioxide (SiO2), and the carbon element is oxidized to carbon dioxide (CO2). The specific reactions are as follows:

[0095]

[0096] Then, the oxidized wafer can react with sodium hydroxide (NaOH) in the electrolyte through the following chemical reaction to achieve material removal:

[0097] SiO2 + 2NaOH → Na2SiO3 + H2O.

[0098] As described above, through the shape control of the flexible adjustable auxiliary electrode 12 and the cooperation of the above plasma thermal oxidation and chemical reactions, precise machining and material removal of the wafer edge chamfer can be achieved, and a target T-shaped chamfer can be machined on the wafer, as shown in Figure 6 Figure (c). And the machined surface is smooth and free of microcracks. Specifically, as shown in Figure 9 Figure Figure 9 Figure (a) is a laser confocal image of the wafer to be machined before chamfering, and (b) is a laser confocal image of the wafer to be machined after chamfering. Among them, the wafer to be machined before machining is a wafer sample obtained by diamond wire cutting, and the cutting results in an uneven damaged layer on the wafer surface, as shown in Figure 9 Figure (a). After the above chamfering process, the damaged layer on the wafer surface can be removed, and the machined wafer surface is smooth and free of microcracks, as shown in Figure 9 Figure (b). Among them, the target chamfer of the wafer chamfering is a T-shaped chamfer, the upper fillet radius R1 of the chamfer is 79.46 μm, and the lower fillet radius R2 is 93.57 μm.

[0099] Example 4

[0100] This example proposes a wafer chamfering method. The main difference between this example and Example 3 is that in this example, the target chamfer of the wafer chamfering is an R-shaped chamfer, specifically as shown in Figure 10 Figure Figure 10 where T represents the total chamfer thickness; X1 represents the horizontal distance of the chamfer leading edge; X2 represents the horizontal distance of the chamfer trailing edge; Y1 represents the vertical distance of the upper part of the chamfer; Y2 represents the vertical distance of the lower part of the chamfer; R represents the chamfer arc radius; A1 represents the upper chamfer angle; A2 represents the lower chamfer angle. The specific operation is similar to that of Example 3.

[0101] The process flow of this wafer chamfering method is as shown in Figure 11 Figure, and specifically includes the following steps:

[0102] (1) Perform the same operation as step (1) in Embodiment 3, provide the wafer to be processed, connect the wafer to be processed to the positive electrode of the power supply, connect the electrode 15 to the negative electrode of the power supply, and inject electrolyte into the receiving groove 11.

[0103] (2) Perform an operation similar to step (2) in Embodiment 3, as Figure 11 shown in (a), relatively arrange the wafer to be processed, the counter electrode 15 and the flexible adjustable auxiliary electrode 12 at intervals, place them in the electrolyte, and at the same time control the flexible adjustable auxiliary electrode to be relatively arranged with the chamfering part to be processed of the wafer to be processed.

[0104] (3) Perform an operation similar to step (3) in Embodiment 3, obtain the predetermined shape of the auxiliary electrode through electric field simulation according to the target chamfer of the wafer to be processed, and set the flexible adjustable auxiliary electrode 12 to the predetermined shape.

[0105] Obtain the predetermined shape of the auxiliary electrode through electric field simulation according to the target R-shaped chamfer of the wafer to be processed. The actuator controller 123 in the flexible adjustable auxiliary electrode 12 sends instructions to each actuator 122 through an electric signal. The actuator 122 regulates the pulling positions and adjustment angles on the flexible electrode 121 through the telescopic cable 125, so as to adjust the flexible electrode 121 to the predetermined shape obtained by simulation, as Figure 11 shown in (b).

[0106] (4) Perform an operation similar to step (4) in Embodiment 3, apply a voltage through the power supply, electrolytic plasma is generated on the edge surface of the wafer to be processed, an oxidation reaction occurs on the edge surface of the wafer to be processed under the action of the electrolytic plasma, and the oxidized wafer reacts chemically with the electrolyte and is removed, and a target R-shaped chamfer is processed on the wafer, as Figure 11 shown in (c), and the processed surface is smooth and has no microcracks.

[0107] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A method for chamfering a wafer, characterized in that, Comprising the following steps: Providing a wafer to be processed, a counter electrode, and a flexible adjustable auxiliary electrode; Connecting the wafer to be processed and the counter electrode to the positive and negative electrodes of a power supply respectively; Placing the wafer to be processed, the counter electrode, and the flexible adjustable auxiliary electrode in an electrolyte; the wafer to be processed and the counter electrode are disposed opposite to each other at an interval, and the flexible adjustable auxiliary electrode is disposed opposite to the chamfering portion to be processed on the wafer to be processed; Obtaining a predetermined shape of the auxiliary electrode through electric field simulation according to the target chamfer of the wafer to be processed, and setting the flexible adjustable auxiliary electrode to the predetermined shape; Applying a voltage through the power supply, generating an electrolytic plasma on the edge surface of the wafer to be processed, and an oxidation reaction occurs on the edge surface under the action of the electrolytic plasma, and the oxidized wafer reacts chemically with the electrolyte and is removed.

2. The wafer chamfering processing method according to claim 1, wherein The concentration of the electrolyte is 1 wt% to 10 wt%; and / or, the voltage is 190 V to 250 V.

3. A wafer chamfering processing device, characterized in that, Including: A containing groove for containing an electrolyte; A power supply having a positive electrode and a negative electrode, and the positive electrode is used to connect to a wafer to be processed; A counter electrode connected to the negative electrode; A flexible adjustable auxiliary electrode configured to be placed in the electrolyte contained in the containing groove in cooperation with the wafer to be processed and the counter electrode, and disposed opposite to the chamfering portion to be processed on the wafer to be processed at an interval for chamfering processing.

4. The wafer chamfering processing device according to claim 3, characterized in that, The flexible adjustable auxiliary electrode includes a flexible electrode and a driving assembly; the flexible electrode is configured to be placed in the electrolyte contained in the containing groove in cooperation with the wafer to be processed and the counter electrode, and disposed opposite to the chamfering portion to be processed on the wafer to be processed at an interval for chamfering processing; the driving assembly is used to regulate the shape of the flexible electrode.

5. The wafer chamfering processing device according to claim 4, characterized in that, The driving assembly includes: An actuator connected to the flexible electrode; An actuator controller communicatively connected to the actuator for controlling the actuator to regulate the shape of the flexible electrode.

6. The wafer chamfering processing device according to claim 5, wherein, A plurality of connecting cable nodes are uniformly arranged on the flexible electrode, and the actuator is connected to the connecting cable nodes through a cable.

7. The wafer chamfering processing device according to any one of claims 3 to 6, characterized in that Further including: An installation assembly including an installation frame, a first fixing member and a second fixing member provided on the installation frame, the first fixing member is provided above the containing groove for fixing the counter electrode; the second fixing member is disposed opposite to the first fixing member and is provided above the containing groove for fixing the wafer to be processed.

8. The wafer chamfering processing device according to claim 7, characterized in that, The second fixing member is slidably connected to the installation frame and is configured to move in a direction close to or away from the flexible adjustable auxiliary electrode.

9. The wafer chamfering processing device according to claim 7, wherein Further including a lifting mechanism provided below the containing groove for controlling the lifting of the containing groove.

10. A wafer chamfering processing system, characterized in that, Including the wafer chamfering processing device according to any one of claims 3 to 9; further including at least one of an electrolyte circulation device, a monitoring device, and a gas recovery device; Among them, the electrolyte circulation device includes a liquid storage tank, a circulation pipeline and a filter; the liquid storage tank is connected to the accommodation tank for storing electrolyte and providing electrolyte for the accommodation tank; the filter is arranged between the accommodation tank and the liquid storage tank and is respectively connected to the accommodation tank and the liquid storage tank through the circulation pipeline; The monitoring device is arranged in the accommodation tank, and the monitoring device is selected from at least one of a temperature sensor, a conductivity sensor, a pH electrode, and a hydrogen sensor; The gas recovery device is used to collect the gas generated by the processing reaction in the accommodation tank.

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