Diamond micron-nanowire manufacturing method based on laser and ion beam

Abstract

The invention discloses a laser and ion beam-based diamond micron-nano wire manufacturing method, and belongs to the technical field of micro-nano machining, and the method comprises the following steps: firstly, preparing a boron-doped diamond film through chemical vapor deposition, and after polishing and cleaning, rapidly machining a diamond micron wire by using femtosecond laser; and then, performing nanoscale fine etching on the micron wire by using a focused ion beam to finally obtain the diamond nanowire. According to the method, through process cooperation and parameter optimization of femtosecond laser and focused ion beams, perfect combination of high efficiency and high precision is achieved, the problems of machining damage, low efficiency or insufficient precision and the like existing in a single technology are effectively solved, and a reliable technical scheme is provided for manufacturing of high-performance diamond nanometer devices.

Description

Technical Field

[0001] This invention relates to the field of micro-nano fabrication technology, and in particular to a method for manufacturing diamond micro-nanowires based on lasers and ion beams. Background Technology

[0002] Diamond, due to its extremely high hardness, excellent thermal conductivity, good biocompatibility, and wide bandgap semiconductor properties, has broad application prospects in high-end sensors, quantum devices, and biomedicine. Diamond nanowires not only retain the excellent properties of bulk diamond, but also exhibit new physicochemical properties due to their huge specific surface area and quantum confinement effect, making their performance particularly outstanding.

[0003] Currently, the manufacturing methods for diamond nanowires mainly include two types of processes: "bottom-up" and "top-down". "Bottom-up" methods form nanostructures through the aggregation of atoms or molecules, but the process is complex and lacks controllability. "Top-down" methods, on the other hand, involve progressively etching or reducing the size of bulk materials or thin films down to the nanoscale, with focused ion beam and femtosecond laser processing attracting significant attention due to their maskless and high-precision characteristics.

[0004] However, in existing technologies, single focused ion beam processing is extremely inefficient, making it difficult to rapidly fabricate large-size structures. Furthermore, high-energy ion beams can easily introduce lattice damage and gallium ion contamination on the material surface. While single femtosecond laser processing is highly efficient, its processing precision is limited, making it difficult to reach the nanoscale. Moreover, thermal effects may cause phase transitions or microcracks in the material.

[0005] To address the aforementioned issues, a method for manufacturing diamond micro- and nanowires based on lasers and ion beams is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for manufacturing diamond micro- and nanowires based on lasers and ion beams, in order to solve the problems in the prior art.

[0007] To achieve the above objectives, the present invention provides a method for manufacturing diamond micro- and nanowires based on lasers and ion beams, comprising the following steps: S1. Preparation of boron-doped diamond film: grow boron-doped diamond film on substrate; S2. Polishing treatment: Polish the boron-doped diamond film to achieve a surface roughness at the nanometer level, and measure the electrical parameters. S3. Cleaning treatment: Ultrasonic cleaning of the polished boron-doped diamond film; S4. Using femtosecond laser to process micron wires: Using a femtosecond laser to process rectangular groove structures on the surface of boron-doped diamond film to form diamond micron wires; S5. Perform a second cleaning: Repeat the cleaning process in step S3 to remove residues generated during laser processing; S6. Nanowire etching using focused ion beam: The cleaned diamond microwires are etched at the nanoscale using a focused ion beam. By controlling the ion beam scanning path and parameters, the micrometer linewidth is etched to the nanoscale to form diamond nanowires.

[0008] Preferably, in step S1, the boron-doped diamond film is grown on a substrate by chemical vapor deposition. The substrate is one of high-resistivity silicon, silicon carbide, or diamond, and the boron doping amount of the boron-doped diamond is 500~5000ppm.

[0009] Preferably, in step S1, the specific steps for growing a boron-doped diamond film on the substrate are as follows: 1) First, check whether each component of the microwave plasma CVD equipment is normal, clean the reaction chamber and install the substrate fixture; then, clean the substrate sequentially with acetone, ethanol and deionized water for 10-15 minutes each, then put it into the chamber, evacuate it and pass H2 through it, and perform H2 plasma etching at a power of 500-800W for 10-30 minutes to remove the oxide layer and introduce nucleation sites. 2) Then the deposition stage begins. During the nucleation stage, the cavity pressure is adjusted to 2-4 kPa, the CH4 / H2 ratio is 2%-5%, the power is 800-1000 W, and the temperature is 800-900℃. The nucleus is formed in 10-30 minutes. During the doping growth phase, the power is increased to 1000~1500W, the pressure is 4~8kPa, the CH4 / H2 ratio is 1%~2%, TMB is introduced, and deposition is carried out at 900~1100℃ for 1~5h. During the annealing phase, the carbon source and boron source are turned off, and only H2 (200sccm) is introduced. Annealing is carried out at 500W power and 800~900℃ for 30~60min. Finally, after the chamber cools down, the sample is taken out, polished with 0.5~1μm diamond polishing paste for 1~2h (to make Ra<1nm), rinsed with deionized water, ultrasonically cleaned for 5~10min, and dried with nitrogen.

[0010] Preferably, in step S2, the thickness of the polished boron-doped diamond film is greater than 15 μm, and the surface roughness is 9~11 nm.

[0011] Preferably, in step S2, the thickness of the polished boron-doped diamond film is 27 μm, and the surface roughness is 10 nm.

[0012] Preferably, the electrical parameters include Hall coefficient, resistivity, carrier mobility, and bulk carrier concentration.

[0013] Preferably, in step S3, the cleaning step involves ultrasonic cleaning with acetone, anhydrous ethanol, and deionized water in sequence, with each cleaning session lasting 5-8 minutes, followed by drying with nitrogen gas after cleaning.

[0014] Preferably, in step S4, the femtosecond laser has a laser power of 2.8~3.6W, a pulse repetition frequency of 10~50kHz, and a scanning speed of 20~40mm / s.

[0015] Preferably, in step S4, the femtosecond laser has a laser power of 3.2W, a pulse repetition frequency of 30kHz, and a scanning speed of 34mm / s.

[0016] Preferably, in step S6, the focused ion beam is a gallium ion beam with an accelerating voltage of 30kV, a beam current of 0.1~20nA, an S-shaped scanning path, 10~1000 scans, and a dwell time of 1μs~1ms.

[0017] Therefore, the diamond micro-nanowire manufacturing method based on laser and ion beam of the present invention has the following beneficial effects: (1) This invention combines the high efficiency of femtosecond lasers with the high precision of focused ion beams, achieving a seamless connection between roughing and finishing, and effectively solving the industry problem of balancing efficiency and precision.

[0018] (2) By optimizing the laser parameters, the present invention effectively suppressed the heat accumulation effect and obtained diamond microwires with flat bottoms and steep sidewalls, which laid a good morphological foundation for subsequent focused ion beam finishing and finally obtained diamond nanowires with complete structure and uniform size.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention; Figure 2 The following are related figures for femtosecond laser processing in Embodiment 1 of the present invention, wherein (a) is a design drawing for processing a rectangular groove, and (b) is a SEM image of the diamond micron wire obtained after processing; Figure 3 The diagrams shown are related to focused ion beam etching in Embodiment 1 of the present invention, wherein (a) is the etching design diagram and (b) is the SEM image of the diamond nanowires obtained after processing. Figure 4 SEM images of diamond nanowires obtained after processing in Example 2 of the present invention are shown, where (a) is a top view and (b) is a front view. Figure 5The images shown are SEM images of diamond nanowires obtained after processing in Example 3 of the present invention, where (a) is a top view and (b) is a front view. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0023] Example 1 This embodiment provides a method for manufacturing diamond nanowires based on laser and focused ion beam, such as... Figure 1 As shown, it includes the following steps: S1. Preparation of boron-doped diamond film: using a size of 8.5 × 8.5 mm. 2 The resistivity is 10000 High-resistivity silicon was used as the substrate for diamond film growth. A boron-doped diamond film with a boron doping concentration of 5000 ppm was grown on the substrate by chemical vapor deposition. The specific operation used in this embodiment is as follows: 1) First, check whether each component of the microwave plasma CVD equipment is normal, clean the reaction chamber and install the substrate fixture; then, ultrasonically clean the substrate with acetone, ethanol and deionized water for 10 minutes each, then put it into the chamber, evacuate it and pass H2 through it, and perform H2 plasma etching at 500W power for 20 minutes to remove the oxide layer and introduce nucleation sites. 2) Then the deposition stage begins. During the nucleation period, the cavity pressure is adjusted to 2 kPa, the CH4 / H2 ratio is 5%, the power is 1000 W, and the temperature is 900℃. This is maintained for 30 minutes to form a diamond nucleus. During the doping growth phase, the power was increased to 1500W, the pressure to 8kPa, and the CH4 / H2 ratio to 2%. TMB was introduced, and deposition was carried out at 900℃ for 1-5 hours. During the annealing phase, the carbon and boron sources were turned off, and only H2 (200 sccm) was introduced. Annealing was carried out at 500W power and 900℃ for 60 minutes. Finally, after the chamber cooled down, the sample was taken out, polished with 1μm diamond polishing paste for 2 hours (to make Ra < 1nm), rinsed with deionized water, ultrasonically cleaned for 5 minutes, and dried with nitrogen.

[0024] S2. Polishing treatment: The boron-doped diamond film is polished to a thickness of 27µm and a surface roughness of approximately 10nm. Simultaneously, an ECOPIAHMS-5300 Hall effect meter is used to measure the Hall coefficient of the boron-doped diamond film to ensure it meets a requirement of 72.3cm. 3 / C, resistivity 0.84 The carrier mobility is 86.2 cm⁻¹. 3 / Vs, the bulk carrier concentration is 8.62×10 16 / cm 3 ; S3. Cleaning treatment: Use acetone, anhydrous ethanol and deionized water to ultrasonically clean the polished boron-doped diamond for 5 minutes each, and then blow it dry with nitrogen. S4. Femtosecond laser processing of micron-wires: Femtosecond laser processing is performed using a high-precision three-axis moving platform multi-pulse-multi-energy field laser composite processing platform. An infrared femtosecond laser is used, and the infrared femtosecond laser processing parameters are set to a power of 3.2W, a repetition frequency of 30kHz, and a scanning speed of 34mm / s. Rectangular grooves are processed on the surface of boron-doped diamond to produce boron-doped diamond micron-wires.

[0025] The specific parameters of the multi-pulse-multi-energy field laser composite processing platform used in this process are shown in Table 1.

[0026] Table 1: Parameters of Composite Machining Platform ;

[0027] During processing, a sample plate thickness of 3mm was used for coarse focal length adjustment. Fine focal length adjustment was achieved by observing and simultaneously adjusting the Z-axis using a charge-coupled device (CCD). The target origin was set at the lower left corner of the diamond. The processing parameters were: edge distance of 0, S-shaped laser path, 100 engraving strokes, 0° starting angle, and 90° cumulative angle. This involved first engraving along a horizontal path, then rotating 90° clockwise for further engraving. The scanning interval was 0.005mm.

[0028] The machined rectangular groove pattern is as follows Figure 2 As shown in (a), the machining parameters a is 0.1 mm and b is 0.5 mm. Figure 2 As shown in (b), the boron-doped diamond microwires obtained by processing have a width of 22.51 μm and a height of 12.25 μm, and are uniform and without defects. S5. Perform a second cleaning: Repeat the cleaning process in step S3 to remove residues generated during laser processing; S6. Nanowire Etching Using Focused Ion Beam: Focused ion beam etching was performed using a TescanLYRA3XMUFIB-SEM system equipped with a gallium ion source and a secondary electron detector. During this process, the accelerating voltage was 30 kV, the beam current was 11 nA, an S-shaped scanning path was used, and the polishing direction was the direction of the pre-reserved diamond wire. The number of scans was 1000, the incident angle was 0°, the beam spot diameter was 250 nm, the pixel overlap rate in both the X and Y directions was 50%, and the dwell time was 1 μs.

[0029] Etched patterns such as Figure 3 As shown in (a), the rectangular scanning mode is selected and the process is carried out in two steps. The specific graphic parameters are divided into ① and ②. In ①, a1 is 5μm, b1 is 10μm, and the initial c1 is 10μm. In ②, a2 is 1μm, b2 is 10μm, and the initial c2 is 10μm. In actual processing, after the diamond etching in ① is complete, ② is then etched.

[0030] Ultimately, the linewidth will be reduced from the micrometer scale to the nanometer scale, such as... Figure 3 As shown in (b), the obtained diamond nanowires have a length of about 10 μm, a width of about 0.8 μm, and a height of about 3.5 μm, achieving the fabrication of diamond nanowires that balances efficiency and precision.

[0031] Example 2 This embodiment follows the same steps as Embodiment 1, except that the infrared femtosecond laser processing parameters in step S4 are modified to a power of 2.8W, a repetition frequency of 40kHz, and a scanning speed of 40mm / s; the SEM image of the processed diamond microgroove is shown below. Figure 4 As shown.

[0032] Example 3 This embodiment follows the same steps as Embodiment 1, except that the infrared femtosecond laser processing parameters in step S4 are modified to a power of 3.2W, a repetition rate of 30kHz, and a scanning speed of 20mm / s. The SEM image of the processed diamond microgroove is shown below. Figure 5 As shown.

[0033] Example 4 This embodiment is the same as the steps in Embodiment 1, except that the infrared femtosecond laser processing parameters in step S4 are modified to a power of 2.8W, a repetition frequency of 10kHz, and a scanning speed of 20mm / s.

[0034] Example 5 This embodiment is the same as the steps in Embodiment 1, except that the infrared femtosecond laser processing parameters in step S4 are modified to a power of 3.6W, a repetition frequency of 50kHz, and a scanning speed of 40mm / s.

[0035] Comparative Example 1 This comparative example uses only a single femtosecond laser for processing, and the specific steps are exactly the same as steps S1-S3 of Example 1, using the same substrate, materials, and pretreatment processes.

[0036] In Example 1, the laser power in step S4 of the femtosecond laser processing of micron-wires was modified to 1.5W, the scanning speed was modified to 100mm / s, and the scanning spacing was reduced to 0.001mm; an attempt was made to directly process the diamond film into nanowires with a width of about 1μm using only femtosecond laser processing.

[0037] Testing revealed that a continuous and complete nanowire structure could not be formed. This is because if the laser energy is too low, it cannot effectively etch the diamond, or if the energy is slightly higher, the material will break or evaporate due to thermal effects, forming irregular nanoparticle chains or completely interrupted grooves, making it impossible to achieve high-precision, high-completeness nanowire manufacturing.

[0038] Comparative Example 2 This comparative example addresses the efficiency issues of directly engraving nanowires from bulk diamond films using focused ion beams. It employs the same sample as in steps S1-S3 of Example 1; omitting the femtosecond laser processing step, it directly uses the same FIB-SEM system and parameters (accelerating voltage 30kV, beam current 11nA) as in step S6 of Example 1 to engrave a structure on the diamond film with a size comparable to the final nanowires of Example 1.

[0039] Testing revealed that while this comparative example could fabricate nanowires with a linewidth of approximately 0.8 μm with high precision, the total processing time was extremely long. Because FIB (Film Injection Bombardment) requires removing a significant amount of material from a 27 μm thick film, the entire process took over 10 hours. Furthermore, the prolonged ion beam bombardment introduced a thicker amorphous damage layer and significant gallium ion implantation contamination onto the nanowire surface, resulting in a substantial negative impact on its electrical and mechanical properties.

[0040] Comparative Example 3 The specific steps in this comparative example are the same as those in Example 1, except that the laser power in step S4 of Example 1, which is used to process micrometer lines with femtosecond laser, is modified to 3.7W, the pulse repetition frequency is modified to 400kHz, the scanning speed is modified to 60mm / s, and the scanning spacing is reduced to 0.01mm.

[0041] Testing revealed that a continuous and complete micron-wire structure could not be formed, rendering the resulting nanowires essentially unusable. This is because the laser processing power and repetition frequency were too high, causing excessive energy accumulation at the same location within a given timeframe. This resulted in over-etching of the diamond, particularly since the laser energy exhibited a Gaussian distribution with extremely high energy at its center. This excessive energy led to over-processing during the rectangular groove process, preventing the formation of nanowires. Furthermore, the high energy caused material melting and re-solidification, further increasing the sidewall tilt angle and hindering the production of high-precision, high-completeness nanowires.

[0042] Comparative Example 4 The specific steps in this comparative example are the same as those in Example 1, except that the laser power in step S4 of Example 1, which is used to process micrometer lines with femtosecond laser, is modified to 2.5W, the pulse repetition frequency is modified to 8kHz, the scanning speed is modified to 80mm / s, and the scanning spacing is reduced to 0.0001mm.

[0043] Testing revealed that continuous and complete nanowire structures could not be formed. This is because the laser processing power was too low and the scanning speed too high, resulting in insufficient energy available in the same area to effectively etch the diamond. High scanning speed means a short dwell time of the laser at the same processing position, resulting in a small thermal effect and a smaller tilt angle. Furthermore, the effect of high scanning speed on diamond is limited, especially with low processing power, making it impossible to achieve high-precision, high-completeness nanowire manufacturing.

[0044] Therefore, the present invention provides a method for manufacturing diamond micron-nanowires based on lasers and ion beams. First, a femtosecond laser is used to rapidly process diamond micron-wires, and then a focused gallium ion beam is used to reduce the linewidth to the nanoscale, thereby achieving rapid processing of the approximate shape and realizing the structural transformation from the micron to the nanoscale. This improves the efficiency and resolution of laser processing and focused ion beam processing, thereby improving the efficiency and precision of manufacturing diamond nanowires.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for manufacturing diamond micro-nano wires based on laser and ion beam, characterized in that, The method comprises the following steps: S1, preparing a boron-doped diamond film: growing a boron-doped diamond film on a substrate; S2, performing polishing treatment: polishing the boron-doped diamond film to make the surface roughness reach the nanometer level and measuring the electrical parameters; S3, performing cleaning treatment: ultrasonic cleaning the polished boron-doped diamond film; S4, processing microwires by using femtosecond laser: using a femtosecond laser to process a rectangular groove structure on the surface of the boron-doped diamond film to form diamond microwires; S5, performing secondary cleaning: repeating the cleaning process of step S3 to remove the residues generated by laser processing; S6, etching nanowires by using a focused ion beam: using a focused ion beam to etch the cleaned diamond microwires to a nanometer level to reduce the line width to the nanometer scale to form diamond nanowires.

2. The method of claim 1, wherein the method is a laser and ion beam based diamond micro- nanowire fabrication method. In the S1, the boron-doped diamond film is grown on the substrate by a chemical vapor deposition method, and the substrate is one of high-resistance silicon, silicon carbide or diamond.

3. The method of claim 1, wherein the method is a laser and ion beam based diamond micro- nanowire fabrication method. In the S2, the thickness of the polished boron-doped diamond film is greater than 15 mu m, and the surface roughness is 9-11 nm.

4. The method of claim 1, wherein the method is a laser and ion beam based diamond micro- nanowire fabrication method. In the S3, the cleaning step is to sequentially use acetone, anhydrous ethanol and deionized water for ultrasonic cleaning, each cleaning time is 5-8 min, and after cleaning, nitrogen is used for drying.

5. The method of claim 1, wherein the method is a laser and ion beam based diamond micro- nanowire fabrication method. In the S4, the laser power of the femtosecond laser is 2.8-3.6 W, the pulse repetition frequency is 10-50 kHz, and the scanning speed is 20-40 mm / s.

6. The method of claim 1, wherein the method is a laser and ion beam based diamond micro- nanowire fabrication method. In the S4, the laser power of the femtosecond laser is 3.2 W, the pulse repetition frequency is 30 kHz, and the scanning speed is 34 mm / s.

7. The method of claim 1, wherein the method is a laser and ion beam based diamond micro- nanowire fabrication method. In the S6, the focused ion beam is a gallium ion beam, the beam current is 0.1-20 nA, and an S-shaped scanning path is adopted.

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