CN103232023B - A kind of silicon microstructure processing method processed based on femtosecond laser with wet etching - Google Patents
A kind of silicon microstructure processing method processed based on femtosecond laser with wet etching Download PDFInfo
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- CN103232023B CN103232023B CN201310141035.2A CN201310141035A CN103232023B CN 103232023 B CN103232023 B CN 103232023B CN 201310141035 A CN201310141035 A CN 201310141035A CN 103232023 B CN103232023 B CN 103232023B
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Abstract
The invention discloses a kind of silicon microstructure processing method processed with wet etching based on femtosecond laser: in oxygen-containing gas atmosphere, utilize femtosecond laser scanning monocrystalline silicon substrate, induce silicon to produce variations in refractive index at scanning area, remove variations in refractive index district again through Fluohydric acid. wet etching and form silicon microstructure.The method technique of the present invention is simple, and compared with prior art, it need not use the distribution pattern of mask plate definition micro structure；Relative to common wet method and dry etching, etch selectivities is good, and etch areas is determined by femtosecond laser processing region completely, is absent from lateral undercutting；The processing of deep silicon groove can obtain depth-to-width ratio height, silicon groove that the degree of depth is big.The method of the present invention can be applicable to MEMS.
Description
Technical field
The invention belongs to MEMS (MEMS) and semiconductor integrated circuit technical field, the processing method relating to a kind of silicon microstructure, especially a kind of deep silicon groove processing method processed with wet etching based on femtosecond laser.
Background technology
In the processing of semiconductor device and MEMS, currently mainly adopt wet etching and be dry-etched on silicon and process micro-nano structure.Wet etching and dry etching are it is generally required to adopt mask definition etch areas.Wet etching utilizes the solution that energy and silicon carry out chemical reaction that silicon is performed etching, and generally adopts alkali (KOH, NaOH etc.) or acid (HF and HNO3Mixed solution etc.) solution.Dry etching is to utilize the effect that plasma passes through chemistry or physics that silicon is realized etching.Anisotropic dry etching is the deep topmost method of silicon groove processing high-aspect-ratio at present.
The deep silicon groove of high-aspect-ratio isolation channel in the semiconductor device, micro-fluidic chip and MEMS has important application.Such as in bulk silicon MEMS device, the electric isolution of micro structure and circuit part and interconnection are a kind of very important technology.Owing to bulk silicon technological and traditional cmos process are incompatible, the silicon isolation channel of formation high-aspect-ratio becomes technological problems urgently to be resolved hurrily.Generally requiring that this isolation channel degree of depth reaches 20～100 μm, depth-to-width ratio is more than 25:1.The method generally adopting deep reaction ion etching (DRIE) processes deep silicon groove.DRIE processing method first adopts photoetching technique to define groove figure, then utilizes inductively coupled plasma (ICP) lithographic technique to be repeatedly performed etching and passivation, until processing enough deep High Aspect Ratio Trench.The depth-to-width ratio of current this method etching silicon groove has reached 40:1.But this method technics comparing is numerous and diverse.
Summary of the invention
It is an object of the invention to the shortcoming overcoming above-mentioned prior art, a kind of silicon microstructure processing method processed based on femtosecond laser with wet etching is provided, it adopts the mode that femtosecond laser irradiates to define etch areas, and the method for recycling wet etching etches silicon microstructure.The method not only operation is more simple, and need not define etch areas by mask.
It is an object of the invention to solve by the following technical programs:
It is this that based on femtosecond laser, the silicon microstructure processing method processed with wet etching is to utilize femtosecond laser scanning monocrystalline silicon substrate in oxygen-containing gas atmosphere, induce silicon to produce variations in refractive index at scanning area, remove variations in refractive index district again through Fluohydric acid. wet etching and form silicon microstructure.
Further, above method specifically carries out according to following steps:
(1) select monocrystalline silicon substrate, clean in acetone, ethanol and deionized water successively；
(2) utilize femtosecond laser to scan the distribution pattern of definition micro structure on silicon in oxygen-containing gas atmosphere, make scanning area refraction index changing；
(3) silicon chip after being processed by femtosecond laser carries out ultrasonic assistant corrosion in Fluohydric acid., removes variations in refractive index region, forms silicon microstructure；
(4) silicon chip after being corroded by Fluohydric acid. cleans in deionized water.
Further, above-mentioned monocrystalline silicon substrate is the silicon chip in<100>,<111>,<110>crystal orientation.
Further, in above step (2), described oxygen-containing gas selects air.
In above-mentioned steps (2), utilizing femtosecond laser scanning monocrystalline silicon substrate to form oxygen containing variations in refractive index region therein, surface laser removes the degree of depth less than 5 microns.
In above-mentioned steps (2), femtosecond laser irradiates the variations in refractive index regional depth produced and width and is controlled by the femtosecond laser energy irradiated, focused condition and scanning speed；The degree of depth in variations in refractive index region is more than 200 microns.
Compared with prior art, the method have the advantages that
The present invention processes based on femtosecond laser and the silicon microstructure processing method technique of wet etching is simple, and compared with prior art, it need not use the distribution pattern of mask plate definition micro structure；Fluohydric acid. only carries out chemical reaction with variations in refractive index region, and relative to common wet method and dry etching, etch selectivities is good, and etch areas is determined by femtosecond laser processing region completely, is absent from lateral undercutting；The processing of deep silicon groove can obtain depth-to-width ratio height, silicon groove that the degree of depth is big.The present invention is lower relative to the laser energy required for the method for femtosecond laser direct etching silicon groove in prior art.The method of the present invention can be applicable to MEMS.
Accompanying drawing explanation
Fig. 1 is the processing unit (plant) figure that this processing method adopts；
Fig. 2 is that the present invention etches silicon microstructure schematic flow sheet；
Fig. 3 is side scanning electron microscope (SEM) image of silicon after femtosecond laser scanning in the inventive method course of processing and etches SEM image and the elements are contained result of silicon flute profile looks；
Fig. 4 is the shape appearance figure of the silicon groove that embodiment 2 finally processes；
Fig. 5 is the shape appearance figure of the silicon groove that embodiment 3 finally processes.
Wherein, 1 is monocrystalline silicon substrate；2 is microcobjective；3 is femtosecond laser；4 produce variations in refractive index region for femtosecond laser induction；5 is HF solution；6 is deionized water；7 is computer；8 is three-D electric translation stage；9 is CCD.
Detailed description of the invention
The present invention processes based on femtosecond laser and the silicon microstructure processing method of wet etching is to utilize femtosecond laser scanning monocrystalline silicon substrate in oxygen-containing gas atmosphere, induce silicon produce variations in refractive index rather than directly remove silicon materials at scanning area, remove variations in refractive index district again through Fluohydric acid. wet etching and form silicon microstructure.The present invention is applicable to the monocrystalline silicon substrate in various crystal orientation, the silicon chip in the present invention preferably<100>,<111>,<110>crystal orientation.
The concrete steps of the method carry out according to following steps:
(1) select monocrystalline silicon substrate, clean in acetone, ethanol and deionized water successively；
(2) utilizing femtosecond laser to scan the distribution pattern of definition micro structure on silicon chip in air or other oxygen-containing gas atmosphere, scanning area generation refraction index changing, without being directly removed or only surface is removed on a small quantity；In this step, utilizing femtosecond laser scanning monocrystalline silicon substrate to form oxygen containing variations in refractive index region therein, surface laser removes the degree of depth below 5 microns.And femtosecond laser irradiates the variations in refractive index regional depth produced and width and is controlled by the femtosecond laser energy irradiated, focused condition and scanning speed；The degree of depth in variations in refractive index region is more than 200 microns.
(3) silicon chip after being processed by femtosecond laser carries out ultrasonic assistant corrosion in Fluohydric acid..The time of ultrasonic assistant corrosion is relevant to the variations in refractive index region that step (2) femtosecond laser induces.Typical time period is 20-40min, but is not limited to this scope.In Fluohydric acid., during corrosion, temperature at 20 DEG C but is not limited to this temperature.The concentration of Fluohydric acid. is about 20%, but is not limited only to this concentration.
(4) silicon chip after hydrofluoric acid solution corrodes is cleaned in deionized water.
After completing above step, it would however also be possible to employ the silicon microstructure of etching is further improved by the method for wet etching.
Below in conjunction with drawings and Examples, the present invention is described in further detail:
Fig. 1 is for realizing a kind of processing unit (plant) schematic diagram of the present invention, it is made up of microcobjective 2, three-D electric translation stage 8, computer 7, femtosecond laser 3., monocrystalline silicon substrate 1 is placed on three-D electric translation stage 8, computer 7 and three-D electric translation stage 8 and be arranged on the CCD above microcobjective 2 and be connected, femtosecond laser 3 is radiated on monocrystalline silicon substrate 1 after microcobjective 2 focuses on.
Utilize the device shown in Fig. 1, provide several embodiments of the present invention below in conjunction with accompanying drawing:
Embodiment 1
The present embodiment is to process deep silicon groove, specific as follows:
Original material: the n type single crystal silicon sheet of single-sided polishing,<100>crystal orientation, thickness 500 μm.
The preparation process detailed embodiment of the deep silicon groove of high-aspect-ratio is described below:
(1) utilize acetone, ethanol and deionized water that monocrystalline silicon substrate 1 is carried out ultrasonic assistant cleaning successively, dried up after cleaning, see Fig. 2 (a).
(2) femtosecond laser 3 pulse width is 50fs, and power setting is 30mW.Select 10 ×, the microcobjective 2 of numerical aperture 0.3, make femtosecond laser 3 focus on monocrystalline silicon substrate 1 by microcobjective 2, three-D electric translation stage 8 sweep speed is 2 μm/s.Utilize femtosecond laser 3 to scan the distribution pattern of groove on silicon chip, see Fig. 2 (b).Femtosecond laser 3 produces variations in refractive index region 4 in scanning area induction, and femtosecond laser 3 is the irradiation area surface removal degree of depth about 5 μm, and deep 270 μm of variations in refractive index region, its scanning electron microscope (SEM) photograph is such as shown in Fig. 3 (a).
(3) monocrystalline silicon piece after laser scanning is carried out in 20%HF solution 5 ultrasonic assistant corrosion, etching time 20min, see Fig. 2 (c).The variations in refractive index region that femtosecond laser 3 induction produces is corroded, and forms silicon groove, sees Fig. 2 (d).Corrosion utilizes deionized water 6 that the silicon chip after HF solution 5 corrosion is carried out ultrasonic cleaning after terminating.
The pattern of the Fig. 3 (a) the silicon groove for finally processing.It can be seen that the degree of depth of groove is 270 μm, depth-to-width ratio is 36:1, it is possible to meet the demand of isolation channel.Fig. 3 (b) measures for the elemental composition of processing silicon groove, only has element silicon, it does not have the pollution of other element around the silicon groove of final processing.
Embodiment 2
Original material: the n type single crystal silicon sheet of single-sided polishing,<100>crystal orientation, thickness 500 μm.
(1) respective process of the cleaning reference example 1 of monocrystalline silicon substrate 1.
(2) femtosecond laser 3 scans the respective process of the process reference example 1 of monocrystalline silicon substrate 1, and parameter is: femtosecond laser 3 pulse width is 50fs, and power setting is 30mW；Select 50 ×, the microcobjective 2 of numerical aperture 0.5；Three-D electric translation stage 8 sweep speed is 2 μm/s.
(3) respective process of the corrosion reference example 1 of silicon chip after femtosecond laser 3 scanning.
(4) respective process of the cleaning reference example 1 of silicon chip after corrosion.
Fig. 4 is the pattern of the silicon groove that embodiment 2 finally processes.It can be seen that the degree of depth of groove is 100 μm, depth-to-width ratio is 8.5:1.
Embodiment 3
Original material: the n type single crystal silicon sheet of single-sided polishing,<100>crystal orientation, thickness 500 μm.
(1) respective process of the cleaning reference example 1 of monocrystalline silicon substrate 1.
(2) femtosecond laser 3 scans the respective process of the process reference example 1 of monocrystalline silicon substrate 1, and parameter is: femtosecond laser 3 pulse width is 50fs, and power setting is 40mW；Select 10 ×, the microcobjective 2 of numerical aperture 0.3；Three-D electric translation stage 8 sweep speed is 2 μm/s.
(3) respective process of the corrosion reference example 1 of silicon chip after femtosecond laser 3 scanning.
(4) respective process of the cleaning reference example 1 of silicon chip after corrosion.
Fig. 5 is the pattern of the silicon groove that embodiment 3 finally processes.It can be seen that the degree of depth of groove is 285 μm, depth-to-width ratio is 44:1.
Claims (3)
1. the silicon microstructure processing method based on femtosecond laser process and wet etching, it is characterized in that: in oxygen-containing gas atmosphere, utilize femtosecond laser scanning monocrystalline silicon substrate, induce silicon to produce variations in refractive index at scanning area, remove variations in refractive index district again through Fluohydric acid. wet etching and form micro structure at silicon face；The method specifically carries out according to following steps:
(1) selecting monocrystalline silicon substrate, clean successively in acetone, ethanol and deionized water, described monocrystalline silicon substrate is the silicon chip in<100>,<111>,<110>crystal orientation；
(2) utilizing femtosecond laser to scan the distribution pattern of definition micro structure on silicon in oxygen-containing gas atmosphere, make the refraction index changing of scanning area silicon, described oxygen-containing gas selects air；
(3) silicon chip after being processed by femtosecond laser carries out ultrasonic assistant corrosion in Fluohydric acid., removes variations in refractive index region, forms micro structure at silicon face；
(4) silicon chip after Fluohydric acid. corrodes is cleaned in deionized water.
2. the silicon microstructure processing method processed based on femtosecond laser with wet etching according to claim 1, it is characterized in that, in step (2), utilizing femtosecond laser scanning monocrystalline silicon substrate to form oxygen containing variations in refractive index region therein, surface laser removes the degree of depth less than 5 microns.
3. the silicon microstructure processing method processed based on femtosecond laser with wet etching according to claim 1, it is characterized in that, in step (2), femtosecond laser irradiates the variations in refractive index regional depth produced and width and is controlled by the femtosecond laser energy irradiated, focused condition and scanning speed；The degree of depth in variations in refractive index region is more than 200 microns.
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| CN106735947A (en) * | 2016-11-30 | 2017-05-31 | 北京理工大学 | A kind of method of efficiently controllable processing bulk silicon micro-nano structure |
| CN106744662A (en) * | 2017-01-12 | 2017-05-31 | 北京理工大学 | A kind of method that utilization dynamic control prepares silicon nanowire structure |
| CN109037026A (en) * | 2017-06-09 | 2018-12-18 | 中国科学院上海高等研究院 | Epitaxial layer shifts monocrystalline silicon seed crystal array substrate and preparation method thereof |
| TWI726225B (en) * | 2018-07-18 | 2021-05-01 | 李俊豪 | Method for manufacturing biochips |
| CN109592685B (en) * | 2018-12-07 | 2020-05-19 | 西南交通大学 | Method for preparing porous silicon by combining laser etching and electrochemical anodic oxidation |
| CN110534880B (en) * | 2019-09-04 | 2020-06-26 | 暨南大学 | Single nanoparticle light scattering electric control antenna and preparation and electric control methods thereof |
| CN113247859B (en) * | 2021-05-13 | 2022-07-15 | 北京理工大学 | Method for preparing crack type nano gap structure based on femtosecond laser |
| CN115535959B (en) * | 2022-11-23 | 2023-04-11 | 山东大学 | Wet etching auxiliary femtosecond laser processing method for monocrystalline silicon microstructure array |
| CN117285002B (en) * | 2023-11-23 | 2024-02-23 | 华东理工大学 | Method for rapidly manufacturing silicon micro-channel by laser induction and wet etching |
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