CN109056051B - Preparation method of silicon-based concave reflector - Google Patents
Preparation method of silicon-based concave reflector Download PDFInfo
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- CN109056051B CN109056051B CN201810937158.XA CN201810937158A CN109056051B CN 109056051 B CN109056051 B CN 109056051B CN 201810937158 A CN201810937158 A CN 201810937158A CN 109056051 B CN109056051 B CN 109056051B
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25F—PROCESSES FOR THE ELECTROLYTIC REMOVAL OF MATERIALS FROM OBJECTS; APPARATUS THEREFOR
- C25F3/00—Electrolytic etching or polishing
- C25F3/16—Polishing
- C25F3/30—Polishing of semiconducting materials
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
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Abstract
The invention discloses a method for preparing a silicon-based concave reflector, which comprises the steps of making a thin platinum sheet which is conventionally used as an electrode into a hollow sphere, making a spherical crown cut from the hollow sphere into a cathode, taking a circular silicon wafer as an anode, and enabling the convex surface of the spherical crown-shaped thin platinum sheet to face the silicon wafer; firstly, performing electrochemical corrosion on a silicon wafer by adopting a constant current source, and forming a porous silicon film with a concave section on one side surface of the silicon wafer close to the spherical crown-shaped thin platinum sheet; and etching off the porous silicon film by adopting a chemical etching method so as to form the silicon-based concave reflecting mirror. The method can obtain the silicon-based concave reflecting mirror, can be widely applied to micro-opto-electro-mechanical systems, and makes a great contribution to the field of micro-opto-electro-mechanical systems.
Description
Technical Field
The invention relates to the field of semiconductor technology and optical engineering, in particular to a preparation method of a silicon-based concave reflecting mirror.
Background
In 1956, Uhlir found the existence of porous silicon when the silicon wafer was subjected to electrochemical polishing treatment in HF solution; in 1990, Canham discovered that porous silicon emits visible light at room temperature, which opens up a new era for the research of porous silicon, namely, the research stage of luminescent porous silicon at room temperature; the luminescence of porous silicon at room temperature shows the wide application prospect of silicon in the aspects of optoelectronics, optical devices, display technology and the like. Particularly, in 1996, the first realization of a silicon-based optoelectronic integrated prototype device by Hirschman is a milestone for the application and research of porous silicon.
The porous silicon film is a spongy porous material with a large specific surface area. The material has the advantages of low cost, good biocompatibility and complete compatibility with the existing integrated circuit process. Although porous silicon has attracted much attention as a high-quality sensor material since the 90 s in the 20 th century, the use of porous silicon materials for optical devices has been rare and is especially rare in the field of optical, mechanical and electrical integration research.
Micro-Electro-Mechanical systems (MEMS) are also called Micro-electromechanical systems, microsystems, micromachines, and the like. The micro-sensor micro-actuator is a high-tech device which integrates a micro-sensor, a micro-actuator, a micro-mechanical structure, a micro-power supply, a micro-energy source, a signal processing and control circuit, a high-performance electronic integrated device, an interface and communication into a whole, and has the size of several millimeters or less.
In recent years, with the rapid development of microelectronic technology, the sizes of electronic devices, MEMS accelerometers, MEMS microphones, micro motors, micro pumps, micro vibrators, MEMS optical sensors, MEMS pressure sensors, MEMS gyroscopes, MEMS humidity sensors, and MEMS gas sensors have become smaller and smaller. The micro-optical-mechanical-electrical system integration research is rapidly developing, silicon-based micro-optical, mechanical, electrical and integration technologies are highly regarded, micro-optical elements such as lenses, prisms and reflectors are important components of the micro-optical-mechanical-electrical system, and can convert, transmit and process micro-optical paths to achieve the purposes of light emission, light collection, light polarization, light interference and light scattering, but the research on the micro-optical elements such as micro-lenses, prisms and reflectors prepared by using porous silicon materials is still few.
There has been much research in the literature on nanoporous silicon Bragg mirrors and their application, but less research on silicon-based concave mirrors.
Disclosure of Invention
The invention aims to provide a preparation method of a silicon-based concave reflecting mirror in order to realize the integration of silicon-based micro-light, mechanical and electrical micro-systems.
In order to achieve the purpose, the invention adopts the technical scheme that: a silicon-based concave reflector is prepared as making thin platinum sheet as electrode into hollow sphere, making a spherical cap cut from hollow sphere as cathode, making circular silicon wafer as anode and making convex surface of spherical cap shaped thin platinum sheet opposite to silicon wafer; the silicon chip and the spherical crown-shaped thin platinum sheet are arranged in parallel, and the central axis of the silicon chip, the circle center of the spherical crown-shaped thin platinum sheet and the central axis of the spherical crown-shaped thin platinum sheet are superposed; firstly, performing electrochemical corrosion on a silicon wafer by adopting a constant current source, and forming a porous silicon film with a concave section on one side surface of the silicon wafer close to the spherical crown-shaped thin platinum sheet; and etching off the porous silicon film by adopting a chemical etching method so as to form the silicon-based concave reflecting mirror.
The principle of the invention is as follows: the preparation of the silicon-based concave reflector is divided into 2 processes, firstly, a silicon wafer is subjected to electrochemical corrosion by using constant-current corrosion current to form a porous silicon film, on one hand, the porous silicon film is formed on the silicon wafer under the condition of normal constant-current corrosion current density, on the other hand, as a constant-corrosion current and spherical-crown-shaped thin platinum sheet electrode is used, the center axis of the spherical-crown-shaped thin platinum sheet is taken as the extension line of the center of the spherical-crown-shaped thin platinum sheet and the bottom perpendicular line of the spherical-crown-shaped thin platinum sheet, the farther from the center axis, the smaller the corrosion current density is, and the slower the speed of forming porous silicon by the electrochemical corrosion on the silicon wafer is, so that the porous silicon film is formed by taking the center axis of the silicon wafer as the center axis, the farther from the center axis, the thinner the porous silicon film is. And secondly, after the concave porous silicon film is prepared, corroding the formed porous silicon film with the concave section by using a sodium hydroxide solution, and corroding the porous silicon film to form the silicon-based concave reflecting mirror.
The curvature radius of the concave reflector can be changed by changing the radius R of the hollow sphere of the thin platinum sheet, the height H of the spherical cap, the distance L between the top D of the spherical cap and the silicon sheet and the electrochemical corrosion condition.
Preferably, the spherical cap height H = 0.05-0.5R of the spherical cap-shaped thin platinum sheet used as the cathode.
Preferably, the concentration of the sodium hydroxide corrosive liquid is 0.1-5%.
Drawings
FIG. 1 is a schematic view of an electrochemical etching cell according to the present invention
Wherein, 1, a corrosion groove, 2, a silicon chip, 3, a spherical crown shaped thin platinum sheet, and D, a spherical crown shaped platinum sheet vertex.
Detailed Description
The present invention will be further described with reference to the following examples. The present invention is not limited to the above-described embodiments, and any modifications and variations may be made by those skilled in the art without departing from the scope of the present invention. Therefore, the following embodiments may be modified or changed in a similar manner without departing from the scope of the invention.
Example one
The preparation method of the silicon-based concave reflecting mirror comprises the following steps:
1. selecting silicon wafer 2 as P type100A circular silicon wafer with the resistivity of 0.01 omega cm and the thickness of 500 mu m is plated with aluminum on the back surface of the silicon wafer to be used as an anode, a thin platinum sheet (with the thickness of 200 mu m) is selected to be made into a hollow sphere, the length of the crown bottom surface of a sphere (the radius of the hollow sphere is 2 cm) cut from the hollow sphere = the diameter of the silicon wafer to be used as a cathode, and the convex surface part of the spherical crown-shaped thin platinum sheet 3 faces the silicon wafer 2; the silicon chip 2 and the spherical crown-shaped thin platinum sheet 3 are completely immersed in an electrolytic corrosion solution for electrochemical corrosion, wherein the electrolytic corrosion solution is prepared by mixing hydrofluoric acid: the volume ratio of absolute ethyl alcohol to deionized water is 1:1: 2.
2. As shown in figure 1, a circuit is connected, namely, corrosive liquid is placed in a corrosion tank 1, a silicon wafer 2 is arranged at one end in the corrosion tank 1, a spherical crown-shaped thin platinum sheet 3 (the thickness is 200 um) is arranged at the other end in the corrosion tank 1, the distance L between the vertex D of the spherical crown-shaped thin platinum sheet 3 and the corrosion center of the silicon wafer 2 is 0.20 cm (which is 0.1 time of the diameter of the corrosion part of the silicon wafer 2), the silicon wafer 2 and the spherical crown-shaped thin platinum sheet 3 (the corrosion diameter of the silicon wafer 2 is equal to the diameter of a circular plane projected by the bottom of the spherical crown-shaped thin platinum sheet 3, and both the diameters are 2 cm) are soaked in the corrosive liquid, the plane where the silicon wafer 2 and the spherical crown-shaped thin platinum sheet 3 are positioned is parallel and the central axes of the silicon wafer 2 and the spherical crown-shaped thin platinum sheet 3 are superposed, a constant current source is arranged outside the corrosion tank 1, the constant current source is generated by an arbitrary waveform generator AFG3101, the anode of the constant current source is connected with the silicon wafer 2 by a lead, and the cathode of.
3. Forming porous silicon with a concave section on a silicon wafer: the current density of the constant current source is 50mA/cm2The etching time was 100Min, and a porous silicon thin film having a concave cross-section was formed on the silicon wafer 2 on the side facing the spherical crown-shaped thin platinum plate 3.
4. Forming a porous silicon concave reflector: and eroding the electrochemically etched silicon wafer into a 1% sodium hydroxide solution (prepared according to the mass ratio of sodium hydroxide to deionized water of 1: 99) for 30 minutes, and eroding off the porous silicon film on the surface of the silicon wafer to form the silicon-based concave reflector.
5. According to the relevant documents and by combining the experimental conditions, the vertical depths of the center and the edge of the bottom of the formed silicon-based concave reflecting mirror surface from the silicon-based polished surface are respectively about 360 and 170 micrometers;
6. after the preparation is finished, washing with deionized water, and finally drying in the air;
7. and (5) obtaining a finished product after the product is qualified through inspection.
Example two
The preparation method of the silicon-based concave reflecting mirror comprises the following steps:
1. selecting the silicon wafer type as P100A circular silicon wafer with resistivity of 0.01 omega cm and thickness of 500 μm, and aluminum plated on the back surface thereof as an anode; selecting a thin platinum sheet (the thickness is 200 mu m) to be made into a hollow sphere, taking the length of the crown bottom surface of a sphere (the radius of the hollow sphere is 2 cm) cut from the hollow sphere = the diameter of a silicon wafer as a cathode, and enabling the convex part of the spherical crown-shaped thin platinum sheet 3 to face the silicon wafer 2; the silicon chip 2 and the spherical crown-shaped thin platinum sheet 3 are completely immersed in an electrolytic corrosion solution for electrochemical corrosion, wherein the electrolytic corrosion solution is prepared by mixing hydrofluoric acid: the volume ratio of absolute ethyl alcohol to deionized water is 1:1: 2.
2. As shown in fig. 1, the circuit is connected: the method is characterized in that corrosive liquid is placed in a corrosion tank 1, a silicon wafer 2 is arranged at one end in the corrosion tank 1, a spherical crown-shaped thin platinum sheet 3 (the thickness is 200 um) is arranged at the other end in the corrosion tank 1, the distance between the vertex D of the spherical crown-shaped thin platinum sheet 3 and the corrosion center of the silicon wafer 2 is 0.20 cm (which is 0.1 time of the diameter of the corrosion part of the silicon wafer 2), the silicon wafer 2 and the spherical crown-shaped thin platinum sheet 3 (the corrosion diameter of the silicon wafer is equal to the diameter of a circular plane projected by the bottom of the spherical crown-shaped thin platinum sheet, and both the diameters are 2 cm) are soaked in the corrosive liquid, and the planes of the silicon wafer 2 and the spherical crown-shaped platinum sheet 3 are parallel and the. A constant current source is arranged outside the corrosion tank 1 and is generated by a TekVisa AFG3101 arbitrary waveform generator, the anode of the constant current source is connected with a silicon wafer 2 through a lead, the cathode of the constant current source is connected with a spherical crown-shaped thin platinum sheet 3 through a lead, and the anode and the cathode of the constant current source form a current loop through corrosive liquid during work.
3. Forming porous silicon with a concave section on a silicon wafer: the current density of the constant current source is 40mA/cm2Etching time is 100Min, and a section is formed on the silicon wafer and on the side facing the spherical crown-shaped thin platinum sheetPorous silicon film with concave surface.
4. Forming a porous silicon concave reflector: and eroding the electrochemically etched silicon wafer into a 2% sodium hydroxide solution (prepared according to the mass ratio of sodium hydroxide to deionized water of 1: 49) for 25 minutes, and eroding off the porous silicon film on the surface of the silicon wafer to form the silicon-based concave reflector.
5. According to experimental measurement, the vertical depth of the center and the edge of the bottom of the formed silicon-based concave reflecting mirror surface from the silicon-based polished surface is about 290 and 135 micrometers;
6. after the preparation is finished, washing with deionized water, and finally drying in the air;
7. and (5) obtaining a finished product after the product is qualified through inspection.
Claims (4)
1. A method for preparing a silicon-based concave reflector is characterized in that a thin platinum sheet which is conventionally used as an electrode is made into a hollow sphere, a spherical crown cut from the hollow sphere is made into a cathode, a circular silicon wafer is used as an anode, the spherical crown height H = 0.05-0.5R of the spherical crown-shaped thin platinum sheet used as the cathode, wherein R is the radius of the hollow sphere where the spherical crown electrode is located; the convex surface of the spherical crown-shaped thin platinum sheet faces the silicon wafer, wherein the length of the bottom surface of the spherical crown is equal to the diameter of the silicon wafer; the silicon chip and the spherical crown-shaped thin platinum sheet are arranged in parallel, the central axis of the silicon chip, the circle center of the spherical crown-shaped thin platinum sheet and the central axis of the spherical crown-shaped thin platinum sheet are superposed, the silicon chip and the spherical crown-shaped thin platinum sheet are both soaked in electrolytic corrosion liquid, and the electrolytic corrosion liquid is prepared from hydrofluoric acid: the absolute ethyl alcohol and the deionized water are prepared according to the volume ratio of 1:1: 2; firstly, performing electrochemical corrosion on a silicon wafer by adopting a constant current source, and forming a porous silicon film with a concave section on one side surface of the silicon wafer close to the spherical crown-shaped thin platinum sheet; and etching off the porous silicon film by adopting a chemical etching method so as to form the silicon-based concave reflecting mirror.
2. The method for manufacturing a silicon-based concave reflecting mirror according to claim 1, wherein the specific process of the electrochemical etching is such that, first, a constant current etching current is used to electrochemically etch a silicon wafer to form a porous silicon thin film, on one hand, the porous silicon thin film is formed on the silicon wafer under the normal constant current etching current density condition, and on the other hand, since a constant etching current and a spherical cap electrode are used, the porous silicon forming speed by the electrochemical etching on the silicon wafer is slower with the center of the spherical cap thin platinum sheet and the bottom perpendicular of the spherical cap as the central axis, and the porous silicon thin film is thinner with the farther distance from the central axis, resulting in the formation of a porous silicon thin film with a concave cross section on one side of the silicon wafer close to the spherical cap thin platinum sheet.
3. The method according to claim 1 or 2, wherein the chemical etching is performed by etching the porous silicon film having a concave cross-section with a sodium hydroxide solution after the concave porous silicon film is formed, and etching away the porous silicon film to form the concave silicon-based mirror.
4. The method of claim 3, wherein the concentration of the NaOH solution is 0.1-5%.
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Citations (5)
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| CN1191903A (en) * | 1996-12-06 | 1998-09-02 | 佳能株式会社 | Electrode structure, electrolytic etching process and apparatus using same, and process for producing photo-electricity generating device |
| CN1743916A (en) * | 2004-09-01 | 2006-03-08 | 精工爱普生株式会社 | Method of manufacturing microlens, microlens, microlens array, electro-optical device, and electronic apparatus |
| CN101175628A (en) * | 2005-05-18 | 2008-05-07 | 松下电工株式会社 | Technique for producing optics lens |
| CN102766892A (en) * | 2012-08-10 | 2012-11-07 | 重庆绿色智能技术研究院 | Micro-nano processing method and device |
| CN106531626A (en) * | 2016-11-08 | 2017-03-22 | 湖南文理学院 | Novel method for improving uniformity of porous silicon radial physical microstructure |
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- 2018-08-16 CN CN201810937158.XA patent/CN109056051B/en active Active
Patent Citations (5)
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|---|---|---|---|---|
| CN1191903A (en) * | 1996-12-06 | 1998-09-02 | 佳能株式会社 | Electrode structure, electrolytic etching process and apparatus using same, and process for producing photo-electricity generating device |
| CN1743916A (en) * | 2004-09-01 | 2006-03-08 | 精工爱普生株式会社 | Method of manufacturing microlens, microlens, microlens array, electro-optical device, and electronic apparatus |
| CN101175628A (en) * | 2005-05-18 | 2008-05-07 | 松下电工株式会社 | Technique for producing optics lens |
| CN102766892A (en) * | 2012-08-10 | 2012-11-07 | 重庆绿色智能技术研究院 | Micro-nano processing method and device |
| CN106531626A (en) * | 2016-11-08 | 2017-03-22 | 湖南文理学院 | Novel method for improving uniformity of porous silicon radial physical microstructure |
Non-Patent Citations (1)
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| 多孔硅层的剥离及反射率研究;陈庆东等;《人工晶体学报》;20071231;第36卷(第6期);1435-1439 * |
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