Electrochemical abrasive water jet sub-aperture processing device and method for semiconductor element

Abstract

The invention relates to an electrochemical abrasive water jet sub-aperture machining device and method based on a semiconductor element, and belongs to the field of ultra-precision machining.The device comprises a water jet system, a direct-current power source, a mechanical arm and a conductive tray; the conductive tray is used for fixing a semiconductor element; the water jet system is used for conveying a polishing solution containing abrasive particles and forming a water jet to act on the semiconductor element; the manipulator is used for adjusting the position and the spraying angle of the water jet relative to the semiconductor element; the positive electrode of the direct-current power supply is connected with the conductive tray, and the negative electrode is connected with the water jet system for providing potential difference for the semiconductor element and the water jet. The oxidation area and the material removal area of the semiconductor element only occur in the water jet impact area, sub-aperture machining is achieved, machining of the curved surface or the surface microstructure of the semiconductor element can be achieved, non-contact machining is achieved, surface scratches and subsurface damage are avoided, and the polishing solution is the sodium chloride deionized water solution and is environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the field of ultra-precision machining, and particularly relates to an electrochemical abrasive water jet sub-aperture machining device and method for semiconductor components. Background Art

[0002] Traditional contact machining methods, such as numerically controlled small grinding head machining and polishing disc machining, highly rely on mechanical action. Although they have a high material removal rate, it is difficult to have both surface quality and cannot completely avoid subsurface damage. Traditional non-contact machining methods, such as ion beam machining, electron beam machining, and magnetorheological machining, rely on media such as high-energy ion beams, electron beams, or magnetically driven rheological fluids to directly remove the surface material of the workpiece, with almost no mechanical action, which can avoid subsurface damage and achieve sub-nanometer roughness, but the material removal rate is low, and there are many technical difficulties to overcome, such as high control difficulty, strict equipment conditions, and high cost.

[0003] To solve the problem that high surface quality and high material removal rate cannot be achieved simultaneously, some scholars have proposed electrochemical machining methods. By adding strong oxidants to the polishing fluid to enhance the oxidation reaction, the removal rate is increased. According to the type of oxidant, it can be divided into acidic oxidants and alkaline oxidants. Some scholars add acidic oxidants such as potassium permanganate and hydrogen peroxide to the polishing fluid to oxidize the surface, and add solutions such as hydrofluoric acid and nitric acid to directly dissolve the oxides. Due to the anisotropy of the material, the chemical reaction is uncontrollable, resulting in irregular bumps and pits on the surface of the workpiece after machining. And most of these methods first oxidize the entire surface of the semiconductor workpiece and then remove the oxide layer, which is a full-aperture machining method. Due to factors such as material anisotropy and high machining accuracy requirements, it is impossible to complete the machining of the curved surface or surface microstructures of semiconductor workpieces, and these methods cannot generate micro-scale features with specific microstructures. Moreover, this electrochemical machining method uses environmentally unfriendly strong oxidants, strong acids, and strong alkalis, which does not conform to the current development concept of green manufacturing. Summary of the Invention

[0004] The purpose of the present invention is to provide an electrochemical abrasive water jet sub-aperture machining device and method for semiconductor components to solve the problems that the existing electrochemical machining methods for semiconductor components cannot complete the machining of the curved surface or surface microstructures of semiconductor workpieces, and strong oxidants, strong acids, and strong alkalis do not conform to the development concept of green manufacturing.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows: The present invention relates to an electrochemical abrasive water jet sub-aperture processing device for semiconductor components, which comprises a water jet system, a DC power supply, a manipulator and a conductive tray; the conductive tray is used for fixing the semiconductor component; the water jet system is used for conveying the polishing liquid containing abrasive grains and forming a water jet acting on the semiconductor component; the manipulator is used for adjusting the position and spraying angle of the water jet relative to the semiconductor component; the positive electrode of the DC power supply is connected to the conductive tray, and the negative electrode is connected to the water jet system, for providing a potential difference for the semiconductor component and the water jet.

[0006] Preferably, the water jet system comprises a polishing liquid storage tank and a nozzle; the polishing liquid storage tank is used for storing the polishing liquid; the nozzle is communicated with the polishing liquid storage tank through a water pump and an adjustment switch, for conveying the polishing liquid and forming a water jet; the nozzle is fixed on the manipulator; the negative electrode of the DC power supply is connected to the nozzle.

[0007] Preferably, a tungsten electrode is arranged inside the nozzle, and the tungsten electrode is conical with the tip facing the liquid outlet of the nozzle.

[0008] Preferably, the polishing liquid adopts a sodium chloride deionized aqueous solution, the conductivity of the polishing liquid is controlled at 0.1 mS / cm to 10 mS / cm, and the ejection pressure of the water jet is 0.5 Mpa to 5 Mpa.

[0009] Preferably, the hardness of the abrasive grains is lower than that of the semiconductor component, and the particle size of the abrasive grains is 30 nm - 800 nm.

[0010] Preferably, the output voltage of the DC power supply is 20 V to 100 V.

[0011] Preferably, the water jet system further comprises a polishing liquid recovery tank, the conductive tray is placed in the polishing liquid recovery tank, and the polishing liquid recovery tank is communicated with the polishing liquid storage tank through a polishing liquid recovery pipeline.

[0012] Preferably, a pressure gauge is further arranged between the nozzle and the polishing liquid storage tank for detecting the spraying pressure of the nozzle; the polishing liquid storage tank is also equipped with an electric stirrer for stirring the polishing liquid containing abrasive grains.

[0013] The present invention also relates to an electrochemical abrasive water jet sub-aperture processing method for semiconductor components, which comprises the following steps: S1. Fix the semiconductor component on the conductive tray, connect the positive electrode of the DC power supply to the conductive tray, and connect the negative electrode to the water jet system, so that the potential difference between the electrodes connecting the semiconductor component and the water jet system reaches a set value; S2. Start the water jet system and adjust the water jet pressure; S3. Start the manipulator to control the machining distance and path of the water jet, ensure that the normal line of the water jet is always at the same angle as the normal line of the semiconductor component machining point, and control the residence time of the water jet at each machining point, thereby performing non-contact sub-aperture machining on the semiconductor workpiece.

[0014] Preferably, in S3, the residence time is obtained by deconvolving the removal function and the surface shape error, and the calculation formula is: , where, is the residence time at any position point coordinate , is the removal function at , is the surface shape error at , and

[0015] is the convolution calculation symbol.

[0015] Adopting the technical solution provided by the present invention, compared with the prior art, it has the following beneficial effects: 1. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components involved in the present invention includes a water jet system, a DC power supply, a manipulator, and a conductive tray. The conductive tray is used to fix the semiconductor component. The water jet system is installed on the manipulator and is used to transport the abrasive polishing liquid and form a water jet acting on the semiconductor component. Moreover, the position, spraying angle, and mainstream time of the water jet relative to the semiconductor component are adjusted through the manipulator. The positive pole of the DC power supply is connected to the conductive tray, and the negative pole is connected to the water jet system, which is used to provide a potential difference for the semiconductor component and the water jet. The oxidation region and the material removal region only occur in the water jet impact region. It is a sub-aperture machining method and can realize the machining of the curved surface or surface micro-structure of the semiconductor component.

[0016] 2. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components involved in the present invention uses sodium chloride deionized aqueous solution as the polishing liquid, and the hardness of the abrasive is lower than that of the semiconductor component. Using sodium chloride deionized aqueous solution as the polishing liquid is environmentally friendly and conforms to the current development concept of green manufacturing. Using abrasives with a hardness much lower than that of the semiconductor component for non-contact machining avoids problems such as surface scratches and subsurface damage. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the electrochemical abrasive water jet sub-aperture machining device for semiconductor components; Figure 2 is a schematic principle diagram of the electrochemical abrasive water jet sub-aperture machining of semiconductor components; Figure 3 is an experimental result diagram of the electrochemical abrasive water jet sub-aperture machining microstructure of semiconductor components.

[0018] Reference numerals: 1 - polishing liquid storage tank, 2 - nozzle, 3 - DC power supply, 4 - manipulator, 5 - conductive tray, 6 - water pump, 7 - adjustment switch, 8 - electric stirrer, 9 - polishing liquid recovery tank, 10 - polishing liquid recovery pipeline, 11 - pressure gauge. Detailed implementation manners

[0019] To further understand the content of the present invention, the present invention will be described in detail in combination with embodiments. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0020] Referring to the attached Figure 1 As shown, an electrochemical abrasive water jet sub-aperture processing device for a semiconductor element according to the present invention includes a water jet system, a DC power supply 3, a manipulator 4, and a conductive tray 5.

[0021] The conductive tray 5 is used to fix the semiconductor element. Among them, the semiconductor element can be a semiconductor material such as silicon carbide (SiC), silicon (Si), gallium nitride (GaN), etc.

[0022] The water jet system is used to transport the polishing liquid containing abrasive grains and form a water jet acting on the semiconductor element. Specifically, it includes a polishing liquid storage tank 1 and a nozzle 2. The polishing liquid storage tank 1 is used to store the polishing liquid containing abrasive grains. The nozzle 2 is connected to the polishing liquid storage tank 1 through a water pump 6 and an adjustment switch 7, and is used to transport the polishing liquid and form a water jet. The nozzle 2 is fixed on the manipulator 4. To conform to the current development concept of green manufacturing and safe manufacturing, the polishing liquid uses a sodium chloride deionized aqueous solution, and the conductivity of the polishing liquid needs to be controlled between 0.1 mS / cm and 10 mS / cm; to achieve no scratches and no subsurface damage on the surface, the hardness of the abrasive grains is lower than that of the semiconductor element, such as cerium oxide, silicon dioxide, etc. To achieve the best processing effect, the particle size of the abrasive grains needs to be controlled between 30 nm and 800 nm. In order to monitor the water flow pressure of the water jet at the nozzle 2 in real time, a pressure gauge 11 is also provided between the nozzle 2 and the polishing liquid storage tank 1 to detect the injection pressure of the nozzle 2 and adjust the water pressure through the adjustment switch 7. The exit pressure of the water jet is 0.5 Mpa to 5 Mpa. In order to make the distribution of the abrasive grains in the polishing liquid more uniform, the polishing liquid storage tank 1 is also equipped with an electric stirrer 8 for stirring the polishing liquid containing abrasive grains. In order to realize the recycling and reuse of the polishing liquid, the water jet system also includes a polishing liquid recovery tank 9. The conductive tray 5 is placed in the polishing liquid recovery tank 9, and the polishing liquid recovery tank 9 is connected to the polishing liquid storage tank 1 through a polishing liquid recovery pipeline 10.

[0023] The manipulator 4 is used to adjust the position and injection angle of the water jet relative to the semiconductor element, ensure that the normal line of the nozzle 2 and the normal line of the processing point of the semiconductor element are at the same angle, perform processing according to the accurate dwell time and processing path, drive the nozzle 2 to move to achieve controllable removal of sub-apertures, and obtain the dwell time distribution through deconvolution of the removal function and the surface shape error. Combining multi-axis linkage can achieve controllable deterministic processing of any surface shape or micro-structure in the entire domain. The calculation formula for the above dwell time is as follows: , wherein, is the dwell time at any position point coordinate , is the removal function at is the surface shape error at is the convolution calculation symbol.

[0024] The positive electrode of the DC power supply 3 is connected to the conductive tray 5, and the negative electrode is connected to the water jet system, specifically to the injection connection, for providing a potential difference for the semiconductor element and the water jet. To achieve the effect of electrochemical anodic oxidation on the surface of the semiconductor element, the output voltage of the DC power supply 3 is 20V - 100V. And, to reduce the influence range of the electrochemical reaction on the surface of the semiconductor element and further improve the processing accuracy, a tungsten electrode can also be provided inside the nozzle 2. The tungsten electrode is conical and its tip faces the liquid outlet of the nozzle 2.

[0025] Referring to the attached Figure 2 shown, taking silicon carbide as an example, the working principle of the above electrochemical abrasive water jet sub-aperture processing device for semiconductor elements is as follows: When the water jet approaches / comes into contact with the surface of the semiconductor element, a suitable positive charge is applied to the semiconductor element to make SiC act as the anode. Under the action of the electric field, the hydroxide ions (OH - in the electrolyte lose an electron (e - ), generating hydroxyl radicals (·OH) and oxygen (O 2 ). These active substances react with the silicon atoms and carbon atoms on the surface of SiC to generate silicon dioxide (SiO 2 ) and carbon dioxide (CO 2 ). Among them, SiO 2 is deposited on the surface of SiC in an amorphous form, forming an easily removable softening layer, while CO 2It escapes in the form of gas. The formation of this oxide layer significantly reduces the surface hardness of SiC. Subsequently, the newly formed oxide layer is continuously removed by the abrasive grains in the water jet impact, exposing a new semiconductor surface. The exposed semiconductor material is oxidized again in the electric field, forming a "oxidation-removal" cycle process. Through this mechanism, the processing efficiency of semiconductor components is significantly improved, achieving sustainable material removal. The manipulator 4 drives the nozzle 2 to achieve controllable removal of the sub-aperture. By increasing the voltage or conductivity, the anodic oxidation of the semiconductor component surface is accelerated, or the pressure is increased to increase the number of times the abrasive grains act on the semiconductor component surface per unit time, thereby improving the material removal rate. The dwell time distribution is obtained by deconvolving the removal function and the surface shape error. Combining the six-axis linkage of the manipulator 4 to ensure that the normal of the water jet and the normal of the processing point of the semiconductor component are at the same angle, and given the accurate dwell time, controllable deterministic processing of any surface shape in the whole domain can be achieved.

[0026] An electrochemical abrasive water jet sub-aperture processing method for semiconductor components based on the above device, which includes the following steps: S1. Fix the semiconductor component on the conductive tray 5 with silver paste with good conductivity. Fix the nozzle 2 of the water jet system at the end of the manipulator 4. Add sufficient polishing liquid containing abrasive grains to the polishing liquid storage tank 1 until the entire water jet system can operate normally. Connect the positive pole of the DC power supply 3 to the conductive tray 5 and the negative pole to the nozzle 2 to make the potential difference between the electrodes connecting the semiconductor component and the water jet system reach the set value. S2. Start the water jet system through the water pump 6. Detect the pressure of the water jet through the pressure gauge 11 and adjust the water jet pressure value to the required value through the adjustment switch 7. S3. Start the manipulator 4 to control the processing distance and processing path of the water jet. For each processing point on the processing path, also control the angle of the nozzle 2 through the manipulator 4, so as to control the normal of the water jet to be always at the same angle as the normal of the processing point of the semiconductor component, and control the dwell time of the water jet at each processing point to reach the calculated value, so as to perform non-contact sub-aperture processing on the semiconductor workpiece.

[0027] In the present invention, the dwell time is obtained by deconvolving the removal function and the surface shape error, and the calculation formula is: , where, is the dwell time at the coordinate of any position point , is the removal function at , is the surface shape error at is the convolution calculation symbol.

[0028] The 4H-SiC silicon surface is processed by the electrochemical abrasive water jet micro-hole diameter processing method of semiconductor components using the above device. Silicon dioxide with a Mohs hardness of 7 is used as the abrasive, and the result is as follows Figure 3 As a result, under the conditions of a conductivity of 1 mS / cm and a voltage of 50 V, by using the electrochemical abrasive water jet micro-hole diameter processing method of semiconductor components involved in the present invention, different microstructures are successfully processed on the surface of silicon carbide, further verifying the remarkable potential of the present invention in high-precision processing.

[0029] The present invention has been described in detail above in conjunction with the embodiments, but the above content is only the preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention shall still fall within the scope covered by the patent of the present invention.

Claims

1. An electrochemical abrasive water jet sub-aperture machining device for semiconductor components, characterized in that: It includes a water jet system, a DC power supply, a manipulator and a conductive tray; the conductive tray is used to fix the semiconductor element; the water jet system is used to transport the polishing liquid containing abrasive particles and form a water jet to act on the semiconductor element; the manipulator is used to adjust the position and spray angle of the water jet relative to the semiconductor element; the positive pole of the DC power supply is connected to the conductive tray, and the negative pole is connected to the water jet system, which is used to provide a potential difference between the semiconductor element and the water jet.

2. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components according to claim 1, characterized in that: The water jet system includes a polishing liquid storage box and a nozzle; the polishing liquid storage box is used to store polishing liquid; the nozzle is connected to the polishing liquid storage box through a water pump and an adjusting switch, and is used to transport polishing liquid and form a water jet; the nozzle is fixed on the manipulator; the negative pole of the DC power supply is connected to the nozzle.

3. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components according to claim 2, characterized in that: A tungsten electrode is arranged inside the nozzle, and the tungsten electrode is conical with the tip facing the liquid outlet of the nozzle.

4. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components according to claim 1, characterized in that: The polishing liquid is a sodium chloride deionized water solution, the conductivity of the polishing liquid is controlled at 0.1mS / cm~10mS / cm, and the ejection pressure of the water jet is 0.5Mpa~5Mpa.

5. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components according to claim 1, characterized in that: The hardness of the abrasive grains is lower than that of semiconductor elements, and the particle size of the abrasive grains is 30nm-800nm.

6. The electrochemical abrasive water jet aperture machining device for semiconductor components according to claim 1, characterized in that: The output voltage of the DC power supply is 20V~100V.

7. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components according to claim 2, characterized in that: The water jet system also includes a polishing liquid recovery box, the conductive tray is placed in the polishing liquid recovery box, and the polishing liquid recovery box is connected to the polishing liquid storage box through a polishing liquid recovery pipeline.

8. The electrochemical abrasive water jet sub-aperture machining device for semiconductor components according to claim 2, characterized in that: A pressure gauge is also provided between the nozzle and the polishing liquid storage tank for detecting the spraying pressure of the nozzle; the polishing liquid storage tank is also equipped with an electric stirrer for stirring the polishing liquid containing abrasive particles.

9. A method for electrochemical abrasive water jet sub-aperture machining of semiconductor components, characterized in that: It includes the following steps: S1. Fix the semiconductor element on the conductive tray, connect the positive electrode of the DC power supply to the conductive tray, and connect the negative electrode to the water jet system, so that the potential difference between the electrodes connecting the semiconductor element and the water jet system reaches a set value; S2. Start the water jet system and adjust the water jet pressure; S3. Start the robot to control the processing distance and processing path of the water jet, control the normal of the water jet to always be at the same angle as the normal of the semiconductor component processing point, and control the residence time of the water jet at each processing point, thereby performing non-contact sub-aperture processing on the semiconductor workpiece.

10. The method for electrochemical abrasive water jet sub-aperture machining of semiconductor components according to claim 9, characterized in that: The S3 is obtained by deconvolving the removal function with the surface shape error to obtain the dwell time, and the calculation formula is: ， in, Any point coordinates The residence time at for The removal function at for The surface error at Computes the sign for the convolution.

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