CN115415664A - Preparation method of black silicon - Google Patents
Preparation method of black silicon Download PDFInfo
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- CN115415664A CN115415664A CN202211154718.7A CN202211154718A CN115415664A CN 115415664 A CN115415664 A CN 115415664A CN 202211154718 A CN202211154718 A CN 202211154718A CN 115415664 A CN115415664 A CN 115415664A
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- 229910021418 black silicon Inorganic materials 0.000 title claims abstract description 19
- 238000002360 preparation method Methods 0.000 title abstract description 9
- 230000006698 induction Effects 0.000 claims abstract description 47
- 239000000463 material Substances 0.000 claims abstract description 25
- 238000000034 method Methods 0.000 claims abstract description 25
- 239000002086 nanomaterial Substances 0.000 claims abstract description 8
- 238000003754 machining Methods 0.000 claims description 17
- 230000001939 inductive effect Effects 0.000 claims 1
- 239000000126 substance Substances 0.000 abstract description 3
- 238000004140 cleaning Methods 0.000 description 5
- 239000012535 impurity Substances 0.000 description 5
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 4
- 230000031700 light absorption Effects 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 239000012153 distilled water Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 239000002210 silicon-based material Substances 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 238000009827 uniform distribution Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000001312 dry etching Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000001039 wet etching Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
- B23K26/04—Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
- B23K26/046—Automatically focusing the laser beam
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K26/00—Working by laser beam, e.g. welding, cutting or boring
- B23K26/70—Auxiliary operations or equipment
- B23K26/702—Auxiliary equipment
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/02—Elements
- C30B29/06—Silicon
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
- C30B33/08—Etching
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Plasma & Fusion (AREA)
- Mechanical Engineering (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Laser Beam Processing (AREA)
Abstract
The invention provides a preparation method of black silicon, which comprises the following steps: after the induction processing of the previous processing path is finished, forming a first light spot on the surface of the current processing path by a laser beam in a focusing mode so as to perform the first induction processing on the current processing path and enable the surface of the current processing path to form a micron-scale structure; and after the first induction processing is finished, forming a second light spot on the surface of the current processing path by the laser beam in a negative defocusing mode so as to perform second induction processing on the current processing path, so that a nano-scale structure is formed on the surface of the current processing path. The preparation method of the black silicon provided by the invention can reduce the protection requirement on materials in the laser processing process and reduce the use of dangerous chemical articles.
Description
Technical Field
The invention relates to the technical field of semiconductors, in particular to a preparation method of black silicon.
Background
There are many ways to prepare black silicon surfaces, including sol-gel methods, electron etching, wet etching, dry etching, laser processing, etc. The laser processing can meet the requirements of the processing structure on the arbitrariness and controllability and the high precision; secondly, laser processing has the advantages of being programmable, suitable for large-area processing, environment-friendly and the like. In addition, the laser processing has structure designability, and is beneficial to the surface design and later-stage preparation of the antireflection structure. At present, two laser processing methods are mainly used for preparing the silicon-based light trapping structure: one is a 'black silicon' technology, pulse laser directly scans silicon-based materials in a sulfur system atmosphere (SF 6, H2S and the like) to generate a peak micron structure; the other is that a pulsed laser irradiates a silicon-based material through a liquid environment (distilled water, sulfuric acid solution, etc.) to produce a columnar structure. However, both methods have the defects of complex operation, complex laser equipment, dangerous chemical articles and the like.
Disclosure of Invention
The preparation method of the black silicon provided by the invention can reduce the protection requirement on materials in the laser processing process and reduce the use of dangerous chemical articles.
The invention provides a preparation method of black silicon, which comprises the following steps:
after the induction processing of the previous processing path is finished, forming a first light spot on the surface of the current processing path by a laser beam in a focusing mode so as to perform the first induction processing on the current processing path and enable the surface of the current processing path to form a micron-scale structure;
and after the first induction processing is finished, forming a second light spot on the surface of the current processing path by the laser beam in a negative defocusing mode so as to perform second induction processing on the current processing path, so that a nano-scale structure is formed on the surface of the current processing path.
Optionally, the diameter of the second spot is 1.15-2.5 times the diameter of the first spot.
Optionally, the diameter of the first light spot is 40-60 μm, and the diameter of the second light spot is 70-100 μm.
Optionally, the distance between the previous processing path and the current processing path is 1/3-3/4 times of the first spot diameter.
Optionally, the distance between the previous processing path and the current processing path is 20-30 μm.
Optionally, the energy density of the first light spot is 0.7-2J/cm 2 (ii) a The energy density of the second light spot is 0.3-0.5J/cm 2 。
Optionally, the output power of the laser used for the first induction processing and the second induction processing is 2-10W, the frequency is 200-400KHz, the pulse wavelength is 650nm or less, and the pulse width is less than 10ns.
Optionally, the current path includes a plurality of processing points, and each processing point is processed by using a light spot formed by 300 to 700 pulses during the first induction processing and the second induction processing.
Optionally, the number of pulses per machining point at the second induction machining is greater than the number of pulses per machining point at the first induction machining.
Alternatively, the material to be treated is set in an air atmosphere at the first induction processing and the second induction processing.
In the technical scheme provided by the invention, a focusing mode is adopted in the first induction processing, so that a first light spot with high energy density is formed on the surface of a material to be processed, a micron-scale light trapping structure is processed, a defocusing mode is adopted in the second induction processing, so that a second light spot with low energy density is formed on the surface of the material to be processed, and a nano-scale light trapping structure is further formed on the surface of the micron-scale light trapping structure, thereby further improving the light absorption capacity of the black silicon. Meanwhile, by adopting the technical scheme provided by the invention, impurities in the next processing path are accumulated to form cleaning when the second large light spot is used for carrying out the second induction processing on the current processing path, so that the protection requirement of the material to be processed in the laser processing process is reduced, and the processing efficiency is improved. The black silicon prepared by the technical scheme of the invention has the pointed cone structure with the height of 3-10 mu m and the light absorption rate of more than 93 percent in the spectral range of 400nm-2.5 mu m.
Drawings
FIG. 1 is a flow chart of a method for preparing black silicon according to an embodiment of the present invention;
fig. 2 is a scanning electron micrograph of black silicon prepared by a method for preparing black silicon according to another embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
The embodiment of the invention provides a preparation method of black silicon, which comprises the following steps:
in some embodiments, the surface of the material to be processed will define multiple processing paths that will be processed in the same manner. In the present embodiment, the machining method of the current machining route is described. The laser beam forms a first spot on the surface of the current processing path in a focusing manner, that is, the focusing position of the laser is set on the surface of the material to be processed. Since the surface of the material to be machined usually has small undulations, the corner points of the laser beam can be set at the average height of the surface of the material to be machined in order to reduce the movement of the follow-up head of the laser during machining. In this way, the following head does not need to follow in the height direction, the distance change between the surface of the material to be processed and the laser is minimal during the processing, and the energy density change of the light spot is within the allowable range even if the surface of the material to be processed slightly fluctuates.
And 200, after the first induction processing is finished, forming a second light spot on the surface of the current processing path by the laser beam in a negative defocusing mode so as to perform second induction processing on the current processing path, so that a nano-scale structure is formed on the surface of the current processing path.
In some embodiments, a negative defocus refers to the focused focus of the laser beam being above the surface of the material to be processed, and a positive defocus refers to the focused focus of the laser beam being below the surface of the material to be processed, i.e. the focus is within the material to be processed. By adopting a defocusing mode, the size of a second light spot formed on the surface of the material to be processed is larger, and meanwhile, the energy density of the second light spot is lower, so that a finer nano-scale structure can be formed on the surface of a micro-scale structure. Although the second light spot with larger size and lower energy density can be formed by adopting the positive defocusing mode, the focus is positioned inside the material to be processed by adopting the positive defocusing mode, and the higher energy at the focus can form cracks on the inside of the material, so that the material is cut. Therefore, in the present embodiment, a negative defocus mode is adopted instead of a positive defocus mode.
In the technical scheme provided by the embodiment of the invention, a focusing mode is adopted during the first induction processing to enable the surface of the material to be processed to form a first light spot with high energy density, so as to process a micron-scale light trapping structure, a defocusing mode is adopted during the second induction processing to enable the surface of the material to be processed to form a second light spot with low energy density, and a nano-scale light trapping structure is further formed on the surface of the micron-scale light trapping structure, so that the light absorption capacity of the black silicon is further improved. Meanwhile, by adopting the technical scheme provided by the embodiment of the invention, the impurities in the next processing path are accumulated to form cleaning during the second induction processing of the current processing path by using the larger second light spot, so that the protection requirement on the material to be processed in the laser processing process is reduced, and the processing efficiency is improved. The black silicon prepared by the technical scheme of the embodiment of the invention has the pointed cone structure with the height of 3-10 mu m and the light absorption rate of more than 93 percent in the spectral range of 400nm-2.5 mu m.
In an alternative embodiment, the diameter of the second light spot is 1.15-2.5 times the diameter of the first light spot. In some embodiments, during the first induction processing of the first light spot, the impurity accumulation is inevitably formed in the region outside the current processing path, and in this embodiment, the diameter of the second light spot is set to be 1.15-2.5 times of the diameter of the first light spot, so that a cleaning effect can be formed on the adjacent region outside the current processing path, so as to reduce the influence of the accumulated impurities on the processing of the next processing path. In a preferred embodiment, the diameter of the first light spot is 40-60 μm, and the diameter of the second light spot is 70-100 μm.
As an alternative embodiment, the distance between the previous processing path and the current processing path is 1/3-3/4 times the diameter of the first spot. In some embodiments, since the processing of the material generally uses a gaussian spot, the energy of the gaussian spot is mainly concentrated around the central region, and in order to improve the distribution uniformity of the micron-scale structures, the distance between the previous processing path and the current processing path is 1/3-3/4 times the diameter of the first spot in this embodiment. Meanwhile, the smaller distance between the processing paths can also ensure that the second light spot covers the next processing path adjacent to the current processing path. Therefore, the cleaning of the next processing path is realized while the second induction processing of the current path is carried out. In a preferred embodiment, the distance between the previous processing path and the current processing path is 20-30 μm.
As an alternative embodiment, the energy density of the first light spot is 0.7-2J/cm 2 (ii) a The energy density of the second light spot is 0.3-0.5J/cm 2 . In some embodiments, the energy density of the second light spot is far less than that of the first light spot, which is beneficial for forming the nano-scale structure on the surface of the micro-scale structure.
As an optional implementation mode, the output power of the laser adopted by the first induction processing and the second induction processing is 2-10W, the frequency is 200-400KHz, the pulse wavelength is 650nm or less, and the pulse width is less than 10ns.
As an alternative embodiment, the current path includes a plurality of processing points, and each processing point is processed by using a light spot formed by 300-700 pulses in the first induction processing and the second induction processing. In some embodiments, the laser light is typically output in pulses, i.e., each pulse comes with the laser light output. In this embodiment, each machining point is stopped for a period of 300-700 pulses, thereby allowing each machining point to be machined by a spot formed by 300-700 pulses.
In an alternative embodiment, the number of pulses per machining point at the second induction machining is greater than the number of pulses per machining point at the first induction machining. In some embodiments, the second induction processing is performed with lower energy and more pulses, which is beneficial to uniform distribution of the thermal field and formation of the nano-scale structure with fine size and uniform distribution on the surface of the micro-scale structure.
As an alternative embodiment, the material to be treated is placed in an air atmosphere during the first induction process and the second induction process. In some embodiments, the second spot is of a larger size than the first spotThe size is larger, and in the secondary induction processing process of the current processing path, impurities in the next processing path are accumulated to form a cleaning effect, so that the processing can be realized in the air atmosphere by the implementation mode without adopting a sulfur system atmosphere environment (SF) 6 、H 2 S, etc.) or a liquid environment (distilled water, sulfuric acid solution, etc.).
An exemplary embodiment of the present invention is provided as follows, which explains the technical solution of the present invention:
the embodiment provides a method for rapidly preparing a large-area micron nano black silicon structure, which is characterized in that an ultrafast laser with the wavelength of 532nm and the pulse width of 500fs is adopted to process a silicon wafer area, and the processing line spacing is 30 micrometers. For each processing line, the first scan used a spot diameter of 50 μm with a spot density of 1J/cm 2 The number of the single-point repeated light spots is 500; the second scan uses a spot diameter of 80 μm with a spot density of 0.3J/cm 2 The number of the single-point repeated light spots is 700. After all the processing is finished, the morphology of the light trapping structure is observed by using a scanning electron microscope, as shown in fig. 2. In the magnified view, the nano-scale structures are grown on the pyramidal microstructures.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A method for preparing black silicon, which is characterized by comprising the following steps:
after the induction processing of the previous processing path is finished, forming a first light spot on the surface of the current processing path by a laser beam in a focusing mode so as to perform the first induction processing on the current processing path and enable the surface of the current processing path to form a micron-scale structure;
and after the first induction processing is finished, forming a second light spot on the surface of the current processing path by the laser beam in a negative defocusing mode so as to perform second induction processing on the current processing path, so that a nano-scale structure is formed on the surface of the current processing path.
2. The method of claim 1, wherein the diameter of the second spot is 1.15-2.5 times the diameter of the first spot.
3. The method of claim 2, wherein the first spot has a diameter of 40-60 μm and the second spot has a diameter of 70-100 μm.
4. The method of claim 1, wherein the distance between the previous processing path and the current processing path is 1/3-3/4 times the first spot diameter.
5. A method according to claim 4, characterized in that the distance between the previous processing path and the current processing path is 20-30 μm.
6. The method of claim 1, wherein the first spot has an energy density of 0.7 to 2J/cm 2 (ii) a The energy density of the second light spot is 0.3-0.5J/cm 2 。
7. The method of claim 1, wherein the first and second inducing processes use a laser output power of 2-10W, a frequency of 200-400KHz, a pulse wavelength of 650nm or less, and a pulse width of less than 10ns.
8. The method of claim 1, wherein the current path comprises a plurality of processing points, each processing point using a spot of 300-700 pulses for processing during the first and second induction processing.
9. The method of claim 1, wherein the number of pulses per machining site at the second induction machining is greater than the number of pulses per machining site at the first induction machining.
10. The method according to claim 1, wherein the material to be treated is placed in an air atmosphere at the first induction processing and the second induction processing.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211154718.7A CN115415664A (en) | 2022-09-21 | 2022-09-21 | Preparation method of black silicon |
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| CN202211154718.7A CN115415664A (en) | 2022-09-21 | 2022-09-21 | Preparation method of black silicon |
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