Anodic bonding method for analyzing a crystal

Abstract

The application discloses an anodic bonding method for analyzing crystals, which comprises the following steps: S1, wet cleaning a substrate; S2, plasma cleaning the substrate and a single crystal wafer after wet cleaning; and S3, bonding the single crystal wafer after plasma cleaning to the substrate through anodic bonding. The application combines wet cleaning and plasma cleaning to obtain clean silicon wafers and borosilicate glass substrates without dust and hydrocarbon contamination in an atmospheric environment of a common laboratory. Subsequently, a common anodic bonding device can be used to obtain an analysis crystal without air bubbles. The method of the application can be applied to the manufacture of spherical crystals, and also includes the manufacture of planar, cylindrical, toroidal, ellipsoidal and other quadratic or multiple function curved surface crystals. The radius of curvature covers 180 mm to 2 m.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of manufacturing of analyzing crystals, and particularly relates to an anodic bonding method of analyzing crystals. BACKGROUND

[0002] Hard X-ray inelastic X-ray scattering is a new technology for studying the meta-excitation of condensed matter based on the rapid development of the third and fourth generation high-energy synchrotron radiation sources, which covers X-ray Raman scattering with an energy resolution of 1eV, resonance inelastic scattering with a resolution of 100meV, and inelastic X-ray scattering with a resolution of meV. These advanced technologies can detect core level electron transitions, electron-hole interactions, magnetic excitations, and phonon information in condensed matter physics, and are powerful tools for studying solid state physics, materials science, and chemistry.

[0003] Spherical bending X-ray analyzing crystals are core optical elements of Rowland circle spectrometers required for the above experimental technologies. They have dual functions of X-ray focusing and energy dispersion. The manufacturing of such optical elements is generally completed by bonding or bonding a single crystal wafer of Si, Ge, quartz, SiC, or sapphire of a certain size on a concave spherical borosilicate glass substrate. Depending on the energy resolution and process flow, it can be roughly divided into low-energy resolution spherical bending crystals (~1eV), medium-energy resolution strip analyzing crystals (100-500meV), and high-resolution pixel analyzing crystals (1-100meV). The application range of analyzing crystals is very broad, and the manufacturing process is extremely complex. Developing high-quality spherical analyzing crystals with good surface accuracy and high energy resolution has always been a challenging world problem, and the related technology is only mastered by a few synchrotron crystal processing laboratories. It is a "neck" key technology that needs to be overcome in the field of domestic synchrotron radiation.

[0004] The manufacturing of analyzing crystals commonly has two process routes of glue bonding and anodic bonding. The glue-bonded crystals have a large error in the final curvature radius due to the chemical substances between the single crystal silicon wafer and the glass substrate. The anodic bonding process does not require the introduction of chemical substances at the interface, so that the single crystal silicon wafer strictly follows the surface of the glass substrate. Therefore, in recent years, the anodic bonding process has gradually developed into the mainstream method for manufacturing analyzing crystals. However, this process requires that there be no foreign matter between the single crystal silicon wafer and the glass substrate, otherwise bubbles will be formed at the interface, resulting in protrusions on the surface of the crystal and thus destroying the surface of the crystal and reducing the X-ray diffraction efficiency of the crystal. Generally, the elimination of bubbles needs to be realized in an ultra-clean room or a vacuum environment, and the corresponding equipment costs up to millions of dollars. For example, the EVG501 wafer bonding system produced by EVG company costs up to 3 million yuan in China, and the equipment is often only suitable for the bonding of planar crystals, and is not suitable for the bonding of spherical or aspherical crystals. SUMMARY

[0005] In order to solve the above problems, the present application provides an anode bonding method with simple operation, low cost and high reliability, which can realize the production of bubble-free analysis crystal by 100%.

[0006] The present application provides an anode bonding method of analysis crystal, comprising: S1, wet cleaning the substrate; S2, plasma cleaning the substrate and single crystal wafer after wet cleaning; and S3, bonding the single crystal wafer after plasma cleaning to the substrate after plasma cleaning by anode bonding.

[0007] According to an embodiment of the present application, the wet cleaning comprises ultrasonic cleaning in distilled water for a certain time, then ultrasonic cleaning in acetone for a certain time, and finally ultrasonic cleaning for a certain time, and then air drying.

[0008] According to another embodiment of the present application, the wet cleaning is carried out in a hundred-level clean bench.

[0009] According to another embodiment of the present application, after the wet cleaning is completed, dust detection is carried out on the cleaned substrate, the dust detection is observing whether there is dust by irradiating the substrate with a green light dust lamp, and if there is dust, blowing it off with air.

[0010] According to another embodiment of the present application, before the single crystal wafer is plasma cleaned, dust detection is carried out on the single crystal wafer, the dust detection is observing whether there is dust by irradiating the single crystal wafer with a green light dust lamp, and if there is dust, blowing it off with air.

[0011] According to another embodiment of the present application, after the plasma cleaning, dust detection is carried out on the single crystal wafer and the substrate, the dust detection is observing whether there is dust by irradiating the single crystal wafer and the substrate with a green light dust lamp, and if there is dust, blowing it off with air.

[0012] According to another embodiment of the present application, the dust detection is carried out in a hundred-level clean bench.

[0013] According to another embodiment of the present application, the anode bonding comprises bonding the edges of the cleaned single crystal wafer and the substrate, and then carrying out anode bonding.

[0014] The present application combines wet cleaning and plasma cleaning to obtain clean silicon wafer and borosilicate glass substrate without dust and hydrocarbon contamination in normal laboratory atmosphere. Subsequently, normal anodic bonding device can be used to obtain bubble-free analysis crystal. The method of the present application can be applied to the fabrication of spherical crystal, and also includes the fabrication of planar, cylindrical, toroidal, ellipsoidal and other quadratic or multiple function curved surface crystal. The curvature radius covers 180mm to 2m. The method of the present application is simple in operation, low in cost and high in reliability, and can realize 100% bubble-free spherical analysis crystal fabrication. The obtained analysis crystal has high diffraction efficiency and good energy resolution. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 are photos of sample 1 and sample 2 prepared in example 1. DETAILED DESCRIPTION

[0016] The present application will be described in detail below in combination with specific embodiments.

[0017] The bubbles generated in the anodic bonding process mainly originate from the dust and CH x contamination on the bonding surface of the single crystal silicon wafer and the glass substrate. Since the single crystal silicon wafer is a polar material, it is easy to adsorb atmospheric particulate matter such as dust when in contact with air, and the dust cannot be eliminated by conventional nitrogen blowing dry method. Meanwhile, since the wafer box is made of plastic, the surface of the wafer will adsorb CH x contamination during storage, making it very difficult to obtain a clean interface. The present application mainly eliminates dust and CH x contamination as much as possible in the laboratory environment.

[0018] The present application provides an anodic bonding method of analysis crystal, comprising: S1, wet cleaning the substrate; S2, plasma cleaning the wet cleaned substrate and single crystal wafer; and S3, bonding the plasma cleaned single crystal wafer to the plasma cleaned substrate by anodic bonding.

[0019] The present application first removes the dust on the substrate by wet cleaning, and the single crystal wafer is not wet cleaned. Then, plasma cleaning is used to remove CH xContamination. The clean single crystal wafer and substrate without dust and hydrocarbon contamination can be obtained in the general laboratory atmosphere. Then, the bubble-free analysis crystal can be obtained by using the general anode bonding device. The method of the present application mainly uses the hundred-level local clean table to realize the wet cleaning, uses the vacuum plasma cleaning device to realize the plasma cleaning, and uses the anode bonding device to realize the anode bonding. The operation is simple, the cost is low, the reliability is high, and the 100% bubble-free spherical analysis crystal can be realized. The obtained analysis crystal has high diffraction efficiency and good energy resolution. The method of the present application can be applied to the production of spherical crystal, and also includes the production of planar, cylindrical, toroidal, ellipsoidal and other quadratic or multiple function curved surface crystals. The curvature radius covers 180 mm to 2 m.

[0020] In an optional embodiment, the wet cleaning includes ultrasonic cleaning in distilled water for a certain time, then ultrasonic cleaning in acetone for a certain time, and finally ultrasonic cleaning for a certain time, and then air drying. The above cleaning time can be reasonably set according to actual needs, for example, 10 minutes, 15 minutes, etc.

[0021] In an optional embodiment, the wet cleaning is carried out in a hundred-level clean table.

[0022] In an optional embodiment, after the wet cleaning of the substrate is completed, dust detection is performed on the cleaned substrate. The dust detection is to observe whether there is dust by irradiating the substrate with a green light dust lamp. If there is dust, blow it off with air. If there is no dust, continue to the next step.

[0023] In an optional embodiment, the single crystal wafer is not subjected to wet cleaning. Before the single crystal wafer is subjected to plasma cleaning, dust detection is performed on the single crystal wafer. The dust detection is to observe whether there is dust by irradiating the single crystal wafer with a green light dust lamp. If there is dust, blow it off with air. If there is no dust, continue to the next step of plasma cleaning.

[0024] In an optional embodiment, after the plasma cleaning, dust detection is performed on the single crystal wafer and the substrate. The dust detection is to observe whether there is dust by irradiating the single crystal wafer and the substrate with a green light dust lamp. If there is dust, blow it off with air. If there is no dust, continue to the next step.

[0025] In an optional embodiment, the dust detection is carried out in a hundred-level clean table.

[0026] In an optional embodiment, the anode bonding includes bonding the edges of the cleaned single crystal wafer and the substrate, and then performing anode bonding.

[0027] The present application will be further described by specific examples. However, these examples are merely exemplary and do not constitute any limitation on the scope of protection of the present application.

[0028] The reagents, materials and apparatus used in the following examples and comparative examples are commercially available unless otherwise stated.

[0029] Example 1

[0030] A. Wet cleaning

[0031] The monocrystalline silicon wafer was purchased from Si’ltronic, France, with a surface accuracy of one quarter wavelength and a thickness of 300 um. The borosilicate glass substrate had a surface accuracy of one tenth wavelength and a curvature radius of 1 meter with a thickness of 12 mm. A small ultrasonic cleaner was placed in a Class 100 local clean bench (Model: Sunyuan Antai VD-650U). The air supply function of the Class 100 clean bench was turned on, and after 15 minutes, the borosilicate glass substrate was placed in distilled water for ultrasonic cleaning for 10 minutes. The borosilicate glass substrate was taken out and placed in the clean bench to dry. Then it was ultrasonically cleaned in acetone for 10 minutes and dried. Finally, it was ultrasonically cleaned in distilled water for 10 minutes and dried. The silicon wafer was not wet cleaned. The monocrystalline silicon wafer and the borosilicate glass substrate were irradiated with a green dust detection lamp, and the presence or absence of dust was observed. If there was no dust, the next step was continued. If there was dust, it was blown off with air.

[0032] B. Plasma cleaning

[0033] The monocrystalline silicon wafer and the borosilicate glass substrate were placed on a polytetrafluoroethylene cleaning basket, and then quickly placed in the cavity of a vacuum plasma cleaner (Nanen Technology 5L). The vacuum pump was turned on, and an appropriate amount of high-purity argon gas was filled to achieve plasma glow discharge. After cleaning for 600 seconds, the radio frequency power was turned off. The vacuum pump was turned off, and high-purity argon gas was filled until the cavity pressure returned to atmospheric pressure. The cavity door was opened quickly to transfer the silicon wafer and the borosilicate glass to a Class 100 local clean bench.

[0034] C. Dust detection

[0035] The surface of the silicon wafer and the glass was observed in the Class 100 local clean bench using a green dust detection lamp. If there were particulate matter or dust, it was blown off with air until there were no obvious foreign substances on the surface of the silicon wafer and the glass.

[0036] D. Anodic bonding

[0037] The cleaner side of the silicon wafer was attached to the concave surface of the borosilicate glass, and the edges of the silicon wafer were bonded to the borosilicate glass with as little polyimide tape as possible. Then the combination was placed on an anodic bonding copper base, and a convex surface bending mold was placed on the silicon wafer. Finally, the temperature of the heating plate was set to 330 degrees, and the voltage was set to 1800V. When the bonding current was lower than 0.01 mA, the bonding was completed, the power was turned off, and the bonded crystal was taken out and cooled.

[0038] Figure 1The photos of sample 1 and sample 2 after B steps are shown, and it can be seen from the photos that the crystals without air bubbles can be obtained by the plasma cleaning, and the surface shape is closer to the ideal spherical surface, and the experimental requirements can be completely met.

[0039] The preferred embodiments of the application disclosed above are only used to help explain the application. The preferred embodiments do not describe all the details and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of the specification. The specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the application, so that those skilled in the art can well understand and utilize the application. The application is limited only by the claims and their full scope and equivalents.

Claims

1. An anodic bonding method of analyzing a crystal, characterized by, The application relates to a method for anodically bonding a single crystal wafer to a substrate, comprising: S1, wet cleaning the substrate; S2, plasma cleaning the wet cleaned substrate and the single crystal wafer; S3, anodically bonding the plasma cleaned single crystal wafer to the plasma cleaned substrate by using a common anodic bonding device. The plasma cleaning is carried out in a vacuum plasma cleaning machine by using high-purity argon plasma glow discharge for 600 seconds. The anodic bonding comprises bonding the edges of the cleaned single crystal wafer and the substrate, and then carrying out anodic bonding. The wet cleaning comprises ultrasonic cleaning in distilled water for a certain time, then ultrasonic cleaning in acetone for a certain time, and finally ultrasonic cleaning for a certain time, and then air drying.

2. The anodic bonding method according to claim 1, wherein The wet cleaning is carried out in a hundred-level clean bench.

3. The anodic bonding method according to claim 2, wherein After the wet cleaning, dust detection is carried out on the cleaned substrate, the dust detection is carried out by irradiating the substrate with a green light dust lamp to observe whether there is dust, and if there is dust, the dust is blown off by air blowing.

4. The anodic bonding method according to claim 2, wherein Before the single crystal wafer is plasma cleaned, dust detection is carried out on the single crystal wafer, the dust detection is carried out by irradiating the single crystal wafer with a green light dust lamp to observe whether there is dust, and if there is dust, the dust is blown off by air blowing.

5. The anodic bonding method according to claim 1, wherein After the plasma cleaning, dust detection is carried out on the single crystal wafer and the substrate, the dust detection is carried out by irradiating the single crystal wafer and the substrate with a green light dust lamp to observe whether there is dust, and if there is dust, the dust is blown off by air blowing.

6. The anodic bonding method according to claim 1, wherein The dust detection is carried out in a hundred-level clean bench.

7. The anodic bonding method according to claim 4, 5 or 6, wherein ​

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