CN102530841B - Processing method of high depth-width ratio microstructure of optical glass - Google Patents

Abstract

The invention discloses a high-aspect-ratio microstructure processing method for optical glass, which is characterized in that high-precision optical glass components are used as research objects, and different indentation shapes and indentation arrays are produced by using different-shaped indenter microhardness testers Based on the mechanical processing method of the pattern, combined with the wet etching process, the samples are etched at different time intervals with different concentrations of BOE solutions (a mixture of HF and NH ₄ F solutions), resulting in different shapes and different height-to-width ratios. Structured high-precision optical glass microstructure.

Description

A high aspect ratio microstructure processing method for optical glass

technical field

The invention relates to an optical glass microstructure processing and etching technology.

Background technique

With the development of large-scale integrated circuit manufacturing technology, micro-machinery has completed the development from unit to system, and successfully applied to the field of optics to form a new hotspot - Micro-Opto-Electro-Mechanical System MOEMS (Micro-Optic-Electro-Mechanical- System), and has been applied in many ways. Since MOEMS needs to perform various optical inspections, it needs to be applied to a large number of transparent materials, and optical glass is the first choice. At present, optical glass has been widely used in MEMS (micro-electromechanical systems), MOEMS, and biochips. In addition to the demand for silicon materials, various new MEMS devices based on optical glass have emerged. Existing The high-aspect-ratio etching technology used in the processing of optical glass microstructures has the following problems: most of the existing technologies use dry etching to directly process high-aspect-ratio structures, and are mostly used for processing anisotropic structures such as silicon crystals. For isotropic materials such as optical glass, it is difficult to control its processing parameters; in addition, this dry etching processing method has high costs and is not suitable for large-scale production and processing; while the existing wet etching It is difficult to process a microstructure with a high aspect ratio on this isotropic material, which requires the development of a high aspect ratio processing technology specially for optical glass .

Contents of the invention

The purpose of the present invention is to find the relationship between the mechanical indentation method and the etching process conditions by studying the influence of different indenters on the shape and holographic characteristics of the optical glass microstructure, and to provide a combination of mechanical and traditional chemical etching. Optical glass high aspect ratio microstructure processing method.

To achieve the above object, the present invention is achieved by taking the following technical solutions:

A high aspect ratio microstructure processing method for optical glass, characterized in that it comprises the following steps:

(1) Take an optical glass sheet as a sample, and use a microhardness tester to make regularly arranged two-dimensional indentations on one side. There are four radial cracks on the four diagonals of each indentation. This radial crack is used for Fabricate high aspect ratio microstructures;

(2) Wrap the periphery of the glass sheet sample with paraffin, leaving only the indented place unwrapped;

(3) Prepare BOE solution, that is, a mixed solution of HF and NH ₄ F for use, wherein the volume concentration ratio of NH ₄ F and HF is 6:1;

(4) Ultrasonic cleaning is performed on the glass sheet sample wrapped with paraffin, and after drying, it is placed in a petri dish filled with BOE solution, so that the BOE solution submerges the glass sheet sample, and the petri dish is etched in a constant temperature water bath at 25°C for at least Take it out after 10 minutes;

(5) Repeat step (4) until the microstructure of cracks with the desired aspect ratio is obtained.

In the above method, the ultrasonic cleaning is three times, the first ultrasonic cleaning with deionized water in a 25°C water bath for 5 minutes; the second ultrasonic cleaning in a water bath with acetone at 25°C for 5 minutes; Ultrasonic cleaning in a water bath for 5 minutes. Described drying adopts nitrogen to blow dry.

The advantages of the present invention are:

1. Combining mechanical processing and chemical etching methods to produce high-precision optical glass high aspect ratio microstructures, the method is fast and operable.

2. It can be selected according to different processing methods, that is, the selection of the shape of the micro-indentation indenter, and the different arrangement and shape of the indentation to make different indentation arrays and produce different crack arrays. These cracks with high aspect ratio structures The array is applied to its suitable field of microfabrication.

3. Apply the wet etching method to the production of high aspect ratio microstructures on the surface of isotropic optical glass, which greatly reduces the processing cost compared with the previous dry etching method, and combined with mechanical processing, it has further enhanced controllability of the present invention.

The invention is suitable for processing finer and deeper (hundreds of micrometers) microchannel microstructures on the K9 glass substrate, and is favored because of its good micromachining performance and relatively cheap price. But the present invention is not limited to K9 glass, and can also be used to make micro- and nano-scale microstructures of brittle optical materials, etc. These microstructures can be widely used in microwave technology, sensors, optical elements and other occasions.

Description of drawings

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic diagram of the indentation of the method of the present invention. Among them: (a) is a schematic diagram of a Vickers regular pyramidal indentation array (two rows); (b) is a schematic diagram of a Knoop indentation array.

Figure 2 is a photo of the indentation made with a force of 4.903N under an optical microscope magnified 1000 times.

Figure 3 shows a paraffin-coated glass sample (four indentations exposed).

Figure 4 is a confocal laser confocal measurement photo of the crack in the indentation in Figure 2 with an indentation force of 4.903N and a dwell time of 10s after 40 minutes of corrosion.

FIG. 5 is a three-dimensional schematic diagram of the indentation after corrosion in FIG. 4 measured by confocal laser.

Fig. 6 is the shape of the array indentation in Fig. 1 after being etched for 30 minutes.

Detailed ways

Micro-hardness testers are used to create micro-scale cracks of various shapes on high-precision optical glass with different indenters, and obtain microstructures with different aspect ratios. Different shapes of indentations and array structures of indentations can be made by using regular quadrangular pyramid indenters, Knoop indenters, regular triangular pyramid indenters, wedge-shaped indenters, double-cone indenters, and double-cylindrical indenters. Based on this, the microstructure with high aspect ratio on the surface of high-precision optical glass is fabricated. As shown in Figure 1(a), two rows of indentations can be made with a Vickers regular pyramid indenter, and the surrounding radial cracks also form regular small cracks. In the same way, a series of indentations can be made with a Knoop indenter. The shape of the indentations is shown in Figure 1(b). The surrounding cracks form a group of regular arrangements. After the next step of corrosion, it can become a structure with a high aspect ratio. Crack groups can be used in microstructures such as MEMS gratings and MEMS switches.

Use different concentrations of BOE solutions to corrode glass samples with indentations on the surface for a certain period of time. Since optical glass is a non-single crystal silicon material, its corrosion is isotropic. Also changes. In this way, through the corrosion of a buffer solution with a certain concentration ratio, the indentation can be corroded and the cracks around the indentation can be enlarged at the same time, so that a desired high aspect ratio microstructure can be produced.

In this embodiment, K9 optical glass is used as the base material, the glass specification is φ12mm, and the thickness is 6mm.

Experimental equipment: HVS-1000 digital display microhardness tester is composed of the main body of the testing machine, worktable, lifting screw, loading system, soft key display operation panel, high magnification optical measurement system and other parts (see Figure 3). Through the soft key input, it can adjust the strength of the measuring light source, preset the holding time of the test force, and switch between Vickers and Knoop test methods. On the LCD display on the soft key panel, it can display the test method, test force, indentation length, hardness value, test force holding time, measurement times, etc., and can input the test time. The specific implementation plan is as follows:

(1) Take a K9 glass sheet of φ12×6mm as a sample, and use a microhardness tester (Vickers hardness tester) to make four square pyramid indentations with different loads on one side, and four pairs of each indentation The corner line has four radial slits, and this radial slit is the structure used in this example to create a high aspect ratio. The indentation made with a force of 4.903N is shown in Figure 2. The different loads are shown in Table 1.

Table 1

Load (GF) 10 300 500 1000 Force (N) 0.0981 2.942 4.903 9.807 Dwell time (S) 10 10 10 10 Crack width (μm) 0.34 0.76 0.82 1.10 Crack depth (μm) 0.67 19.25 22.23 28.7

(2) Wrap the periphery of the glass sample with paraffin, leaving only the indented area unwrapped, as shown in Figure 3. The purpose of this is to ensure that the measurement reference plane is not damaged.

(3) Preparation of BOE solution (mixed solution of HF and NH ₄ F): 90 g of NH ₄ F was dissolved in 130 ml of water to form a 40% NH ₄ F solution, and 180 ml was taken for use;

Then take 15ml of HF acid with a mass concentration of 40% and add 17ml of water to dilute it into an HF acid solution with a mass concentration of 18.75%, add it to 180ml of NH ₄ F solution and mix to obtain a BOE solution. The volume concentration ratio of NH ₄ F and HF at this time was 6:1.

(4) Cleaning of glass slides: First, put the sample in a glass beaker filled with deionized water and use a 25°C water bath to ultrasonically clean it for 5 minutes, then put it into a plastic beaker filled with acetone and heat it in a 25°C water bath. Ultrasonic cleaning for 5 minutes, then put it into a glass beaker filled with absolute ethanol, use a water bath at 25°C and ultrasonic cleaning for 5 minutes, take it out, and dry it with nitrogen.

(5) Put the sample in a plastic petri dish filled with the BOE solution prepared in the third step (so that the BOE solution submerges the sample glass), and put the petri dish into a constant temperature water bath (25°C) for corrosion, after 10 minutes Then take it out.

(6) Observing with a laser confocal microscope, the width d ₁ and depth h ₁ of the crack are measured, and the ratio is ω ₁ =h ₁ /d ₁ , at this time, the microscopic depth-width ratio of the surface of the isotropic glass material can be obtained. structure.

(7) Steps (4) and (5) can also be repeated to obtain ω ₂ =h ₂ /d ₂ , ω ₃ =h ₃ /d ₃ , ..., ω _n =h with further improved aspect ratio _n /d _n .

For example, where the indentation strength is 4.903N and the dwell time is 10s, the crack width measured by laser confocal microscope after being corroded for 40 minutes is d ₄ =2.372μm, h ₄ =24.718μm, then The aspect ratio at this time is ω ₄ =10.420, and the measurement results are shown in FIG. 4 . Figure 5 is a three-dimensional schematic view of the indentation.

Various array structures can be processed during processing (Fig. 1). This not only ensures diversification, but also expands its application value. Figure 6 is the pattern observed under the laser confocal microscope after the array of square pyramid indentations in Figure 1 was corroded for 30 minutes. The obtained multi-tissue pattern has a high aspect ratio and can be well applied in the processing of micro-sensors and micro-optical devices. Such arrays of high-aspect-ratio cracks can be used to process micro-gratings with arrays of high depth-width The micro-devices of the specific structure can reflect its application value.

Claims (2)

1. A high aspect ratio microstructure processing method of optical glass, characterized in that, comprising the following steps: (1) Take an optical glass sheet as a sample, and use a microhardness tester to make regularly arranged two-dimensional indentations on one side. There are four radial cracks on the four diagonals of each indentation. This radial crack is used for Fabricate high aspect ratio microstructures; (2) Wrap the periphery of the glass sample with paraffin, leaving only the indented area unwrapped; (3) Prepare BOE solution, that is, a mixed solution of HF and NH ₄ F for use, wherein the volume concentration ratio of NH ₄ F and HF is 6:1; (4) Ultrasonic cleaning is performed on the glass sheet sample wrapped with paraffin, dried and placed in a petri dish filled with BOE solution, so that the BOE solution submerges the glass sheet sample, and the petri dish is corroded in a constant temperature water bath at 25°C for at least Take it out after 10 minutes; (5) Repeat step (4) until the microstructure of cracks with the required aspect ratio is obtained. 2. The high aspect ratio microstructure processing method of optical glass as claimed in claim 1, characterized in that, the ultrasonic cleaning is three times, the first time with deionized water 25 ℃ water bath ultrasonic cleaning for 5 minutes; the second time Ultrasonic cleaning with acetone in a 25°C water bath for 5 minutes; third time ultrasonic cleaning in a 25°C water bath with absolute ethanol for 5 minutes.