CN101913552B - Method for preparing suspension micro-sensitive structure based on aluminum sacrificial layer process - Google Patents

Abstract

The invention discloses a method for preparing a suspension micro-sensitive structure based on an aluminum sacrificial layer process. The method comprises the following steps of: introducing a sacrificial layer into a three-layer suspension micro-sensitive structure to restrict a micro-sensitive suspension mass block during the processing, and connecting the suspension micro-sensitive structure and bulk silicon by using an aluminum light film so as to avoid influence of subsequent processing on the suspension structure; removing the sacrificial layer by wet etching; and finally replacing an etching solvent with clean water and ethanol, and drying. The method effectively ensures the integrity and mobility of the suspension micro-sensitive structure without changing the conventional process flow, does not reduce the performance of a micro-mechanical sensor because the mechanical restriction is not increased, reduces the process difficulty, improves the yield and can be widely used for processing various silicon micro-components with the suspension micro-sensitive structure.

Description

A preparation method of suspended micro-sensitive structure based on aluminum sacrificial layer technology

technical field

The invention relates to the field of preparation technology for micro-silicon device processing, in particular to a method for preparing a suspended micro-sensitive structure based on an aluminum sacrificial layer technology.

Background technique

Micro-silicon electromechanical processing technology is the mainstream technology of micro-electro-mechanical systems MEMS developed with integrated circuit technology in recent years. Micro-silicon devices are manufactured using micro-electromechanical system microelectronics and micro-machining technology. It has small size, light weight, low cost, low power consumption, high reliability, suitable for mass production, easy integration and realizable Intelligent features. At the same time, the feature size on the order of microns enables it to perform functions that some traditional mechanical sensors cannot achieve, so microelectronics and micromachining technology of microelectromechanical systems are increasingly becoming the main development direction of microsilicon device manufacturing processes.

In the microsilicon device method processed by the microelectronics and micromachining technology of the microelectromechanical system, the glass-silicon-glass three-layer flat plate structure is a typical structure of the micromechanical sensor processed by it, that is, in the silicon micromechanical device It usually contains a suspended mass that senses acceleration or force. This slightly sensitive suspended mass is generally etched from bulk silicon, which is limited to the existing bulk silicon processing technology in my country. During the processing process, the suspended mass has no or only With very small mechanical constraints, the micro-sensitive suspended mass can easily cause structural distortion during subsequent cleaning and processing, or enter and exit from the silicon cavity, resulting in degradation or destruction of device characteristics. There are two ways to solve this problem: increase the mechanical constraints of the micro-sensitive suspended structure during the design process and introduce sacrificial layers that are removed after processing. However, increasing the mechanical constraints will inevitably lead to a decrease in the performance of the micromechanical sensor. At the same time, due to the small internal space and relatively closed structure of the glass-silicon-glass sandwich structure, the current sacrificial layer technology for this structure is not mature. Now some Technology has tried to introduce a silicon dioxide sacrificial layer, but due to the certain damage to the bulk silicon when removing the sacrificial layer, the processing difficulty of micro-silicon devices has been greatly increased, resulting in micro-mechanical sensors generally facing difficulties in processing, high processing costs, Low yield and other issues.

Contents of the invention

In order to overcome the deficiencies in the above-mentioned prior art, the object of the present invention is to provide a process for preparing a suspended micro-sensitive structure based on the aluminum sacrificial layer process, through the glass-silicon-glass three-layer suspended micro-sensitive structure in the process of processing Introduce a sacrificial layer to constrain the micro-sensitive suspended mass, and use an aluminum thin film to connect the suspended micro-sensitive structure and bulk silicon to avoid the impact of subsequent processing on the suspended structure. After completion, wet-etch the sacrificial layer Finally, replace the etching solvent with water and ethanol, and dry the microstructure; this method effectively ensures the integrity and mobility of the suspended microsensitive structure without changing the original process flow, and does not need to be enlarged. The mechanical constraint will not cause the degradation of the performance of the micromechanical sensor, and at the same time reduce the difficulty of the process and improve the yield, and can be widely used in the processing of various silicon microdevices with suspended movable sensitive structures.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for preparing a suspended micro-sensitive structure based on an aluminum sacrificial layer process, the steps are as follows:

Step 1: Etch more than one electrode groove 3 with a depth of 120 to 160 nm on the surface of the top glass 1 and the bottom glass 2 respectively by buffered hydrofluoric acid BHF wet method. Outwardly extending lead groove 60, and according to the order from left to right, the size and longitudinal position of each pair of electrode grooves 3 corresponding to the top glass 1 and the bottom glass 2 are consistent, such that each pair of electrode grooves 3 constitutes a differential Move the electrode groove, and then sputter 170-210nm thick titanium gold alloy in each electrode groove 3 to form more than one electrode 41, and sputter the lead wire 42 extending outward on the outer surface of each electrode 41 to enter Corresponding to the lead groove 60 of the electrode groove 3, the width of each lead 42 is not less than 30 μm, and the interval between adjacent lead wires 42 is not less than 10 μm, so that the top glass 1 with the electrode 41 and the top glass with the electrode 41 are obtained. The underlying glass 2, and the number, size and position of the electrodes 41 and their lead wires 42 in each pair of differential electrode grooves 3 are also correspondingly consistent, and each pair of correspondingly consistent electrodes 41 and their lead wires 42 constitutes a differential electrode 4 ;

Step 2: Use an n-type or p-type crystal-oriented single-crystal silicon wafer 5 with a resistivity of 0.002-0.004 Ω·cm. After standard cleaning, use reactive ion etching RIE or inductively coupled plasma ICP dry The bottom surface of the silicon wafer 5 is etched to form more than one electrode lead shallow groove 6, the depth of which is 5-10 μm, and in order from left to right, the electrode lead shallow grooves 6 on the bottom surface of the silicon wafer 5 can accommodate the bottom layers one by one. The lead 42 in the corresponding electrode groove 3 in the glass 2, and the protruding plane between each adjacent electrode lead shallow groove 6 constitutes the bonding table 52; wherein the standard cleaning is to use 80% pure sulfuric acid and 20% hydrogen peroxide mixed solution to clean the silicon chip 5 for 3-5 minutes to remove the organic matter on the silicon chip 5, then mix the ammonia water, hydrogen peroxide and pure water with a mass concentration of 60% according to the mass ratio of 1:1:5, and use The mixed solution cleans the silicon chip 5 for 3-5 minutes to remove the non-metallic contamination on the silicon chip 5, and finally mixes hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% according to the mass ratio of 1:1:5, and uses The mixed solution cleans the silicon wafer 5 for 3-5 minutes to remove metal contamination on the silicon wafer 5;

Step 3: then make more than one aluminum film 7 as a sacrificial layer on the bottom surface of the silicon wafer 5 by metal sputtering, thus forming a silicon wafer 5 with an aluminum film 7, the thickness of each aluminum film 7 500-1000nm, all aluminum films are located on the bottom surface of the silicon wafer 5 and within the preset vertical projection of the edge of the suspended micro-sensitive structure 51;

Step 4: Clean the silicon chip 5 with the aluminum film 7 for 3-5 minutes with a mixed solution of 80% pure sulfuric acid and 20% hydrogen peroxide by mass to remove organic matter on the silicon chip 5, and then clean the silicon chip 5 with a mass concentration of 60% Ammonia, hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the silicon wafer 5 with the aluminum film 7 is cleaned with the mixed solution for 3-5 minutes to remove non-metallic contamination on the silicon wafer 5, and finally Mix hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% according to the mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 with the aluminum film 7 for 3-5 minutes to remove the silicon wafer 5. metal pollution; then carry out the bottom glass-silicon electrostatic bonding, that is, the silicon wafer 5 with the aluminum film 7 and the bottom glass 2 with the electrode 41 are in contact together, and in order from left to right, the silicon wafer 5 The electrode lead shallow grooves 6 on the bottom surface of the bottom surface are in turn opposed to the corresponding electrode grooves 3 in the bottom glass 2 one by one, and then a DC voltage of 800-1500V is applied at 350-450 degrees Celsius, and the silicon chip 5 is connected to the positive pole of the DC power supply, and the bottom glass 2 Connect the negative pole of the DC power supply, and the bonding is completed after 25 to 30 minutes of switching on the DC voltage;

Step 5: After the bottom glass-silicon is electrostatically bonded, the thickness of the silicon wafer 5 is uniformly etched and thinned from the upper end to 100-150 μm with a mass concentration of 25% tetramethylammonium hydroxide TMAH etching solution, and then used The silicon wafer 5 is polished with a phosphating solution with a concentration of 25%, and the polishing time is 3-6 minutes;

Step 6: Reactive ion etching (RIE) or inductively coupled plasma (ICP) dry method is used to etch the upper surface of the silicon wafer 5 to form more than one electrode lead shallow groove 6, the depth of which is 5-10 μm, And according to the order from left to right, the shallow electrode lead grooves 6 on the upper surface of the silicon wafer 5 can accommodate the lead wires 42 in the corresponding electrode grooves 3 in the top glass 1 one by one, and each adjacent electrode lead shallow groove 6 The protruding planes in between constitute the bonding mesa 52; the standard cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer 5 for 3-5 minutes to remove the organic matter on the silicon wafer 5, Next, mix ammonia water, hydrogen peroxide and pure water with a mass concentration of 60% according to the mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 for 3-5 minutes to remove non-metallic contamination on the silicon wafer 5, Finally, mix hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% according to a mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 for 3-5 minutes to remove metal contamination on the silicon wafer 5;

Step 7: Then adopt the inductively coupled plasma ICP dry method, respectively place the electrode groove 3 along the edge of the preset floating micro-sensitive structure 51 and the edge of the electrode groove 3 with the outwardly extending lead groove 60 on the outside of the bottom glass 2. The silicon wafer 5 is carved vertically without penetrating the aluminum film 7 to form a suspended micro-sensing structure 51 and conductive silicon 54. The other parts of the silicon wafer are bulk silicon 53, and the bulk silicon 53 passes through the aluminum film 7 and the suspended micro-sensing structure 51. In addition, grooves 8 are carved laterally on the side of the bulk silicon 53, thus forming a bottom glass-silicon chip assembly with suspended micro-sensitive structures 51 and conductive silicon 54;

Step 8: Wash the bottom glass-silicon wafer combination sheet with a solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 3-5 minutes to remove organic matter on it, and then treat the ammonia water with a mass concentration of 60%, Hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer composite sheet is cleaned with the mixed solution for 3-5 minutes to remove the non-metallic contamination on it, and finally, the mass concentration is 30%. Hydrochloric acid, hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer assembly sheet is cleaned with the mixed solution for 3-5 minutes to remove the metal contamination on it; then the top glass -Silicon electrostatic bonding, that is, the bottom glass-silicon wafer composite sheet and the top glass 1 with electrodes 41 are in contact together, and in order from left to right, the electrode lead shallow grooves 6 on the upper surface of the silicon wafer 5 are sequentially One by one, it is opposite to the corresponding electrode grooves 3 in the top glass 1, and then a DC voltage of 800-1500V is applied at 350-450 degrees Celsius. The bulk silicon 53 is connected to the positive pole of the DC power supply, and the top glass 1 is connected to the negative pole of the DC power supply. After 25-30 minutes of DC voltage, the bonding is completed to obtain a three-layer composite sheet;

Step 9: immerse the three-layer composite sheet in an aluminum etchant, and ultrasonically clean it for 20 to 30 minutes to remove the aluminum film 7 as a sacrificial layer. The aluminum etchant is composed of phosphoric acid with a mass concentration of 85%, Nitric acid, acetic acid and water with a mass concentration of 70% are mixed according to volume percentages of 10-30%, 0.5-2%, 5-10% and 60-80% respectively;

Step 10: Immediately take the three-layer composite chip out of the aluminum etchant, wash it with clean water for 20-30 minutes in an ultrasonic environment, and replace it with suspended micro-sensitive structure 51, conduction silicon 54 and bulk silicon 53 Residual reactants and aluminum etchant inside the structure are cleaned with ethanol for 10 to 30 minutes in an ultrasonic environment to replace clean water, thus completing the preparation of the suspended micro-sensitive structure based on the aluminum sacrificial layer process.

By this method, after the bottom glass-silicon is electrostatically bonded, and before the suspended microsensitive structure 51 is processed on the silicon wafer 5, the aluminum film 7 as a sacrificial layer is introduced so that the subsequently processed suspended microsensitive structure 51 and the bulk silicon 53 together, on the one hand to prevent the suspended micro-sensitive structure 51 from falling off during the etching process, and on the other hand to provide an elastic force opposite to the electrostatic force generated by the bonding during the top glass-silicon electrostatic bonding process, so that The suspended microsensitive structures 51 are not attracted to the top glass 1 during the bonding process. In addition, the aluminum film 7 serving as the sacrificial layer can be easily removed with an aluminum etchant at the end. In addition, nitric acid in the aluminum etchant oxidizes aluminum into aluminum oxide, and then phosphoric acid dissolves it into phosphate. Acetic acid is mainly used to reduce the surface tension of the corrosion solution, increase the infiltration of the aluminum film surface and the corrosion solution, and improve the corrosion resistance. Uniformity plays a buffer role. This solution effectively ensures the integrity and mobility of the suspended micro-sensitive structure 51 without changing the original process flow, and will not cause performance degradation of the micro-mechanical sensor without increasing mechanical constraints. It can be widely used in the processing of various silicon micro devices with suspended movable sensitive structures.

Description of drawings

Fig. 1 is a schematic view of the state of the top glass and the bottom glass in step 1 of the present invention.

Fig. 2 is a structural schematic diagram of an electrode groove of the top glass in step 1 of the present invention.

Fig. 3 is a schematic structural view of an electrode groove of the bottom glass in step 1 of the present invention.

Fig. 4 is a schematic structural diagram of the silicon wafer in step 3 of the present invention.

Fig. 5 is a schematic diagram of the state of forming the suspended micro-sensitive structure in step 7 of the present invention.

Fig. 6 is a schematic bottom view of a partial structure with an aluminum film in step 7 of the present invention.

Fig. 7 is a schematic diagram of a partial top view structure with a suspended micro-sensitive structure in step 7 of the present invention.

Fig. 8 is a schematic diagram of the state of the present invention having completed the preparation of the suspended micro-sensitive structure based on the aluminum sacrificial layer process.

Detailed ways

Below in conjunction with embodiment the present invention is described in more detail.

Example 1:

The preparation method of the suspended micro-sensitive structure based on the aluminum sacrificial layer technology in this embodiment, the steps are as follows:

Step 1: Etch three 120nm-deep electrode grooves 3 on the surface of the top glass 1 and the bottom glass 2 respectively with buffered hydrofluoric acid BHF wet method, each electrode groove 3 has an outwardly extending Lead groove 60, and in order from left to right, the size and longitudinal position of each pair of electrode grooves 3 corresponding to the top glass 1 and the bottom glass 2 are consistent, and each pair of electrode grooves 3 constitutes a differential electrode groove groove, and then sputter 170nm thick titanium gold alloy in each electrode groove 3 to form four electrodes 41, and sputter outwardly extending leads 42 into the corresponding electrode groove 3 on the outer side of each electrode 41 lead groove 60, the width of each lead 42 is 35 μm, and the interval between adjacent lead 42 is 15 μm, so just obtain the top glass 1 with electrode 41 and the bottom glass 2 with electrode 41, and each pair The number, size and position of the electrodes 41 and their lead wires 42 in the differential electrode groove 3 are also correspondingly consistent, and each pair of correspondingly consistent electrodes 41 and their lead wires 42 constitute a differential electrode 4 as shown in Figures 1, 2 and Fig. 3 shown;

Step 2: Use an n-type crystal-oriented single crystal silicon wafer 5 with a resistivity of 0.002Ω·cm, perform standard cleaning, and then etch the bottom surface of the silicon wafer 5 by reactive ion etching (RIE) to form three electrode leads The shallow groove 6 has a depth of 5 μm, and according to the order from left to right, the electrode lead shallow groove 6 on the bottom surface of the silicon wafer 5 can successively accommodate the lead wires 42 in the corresponding electrode grooves 3 in the bottom glass 2 one by one, and each The protruding planes between the adjacent electrode lead shallow grooves 6 constitute the bonding mesa 52; the standard cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer 5 for 3 minutes to remove The organic matter on the silicon chip 5 is then mixed with ammonia water, hydrogen peroxide and pure water with a mass concentration of 60% in a mass ratio of 1:1:5, and the silicon chip 5 is cleaned for 3 minutes with the mixed solution to remove the organic matter on the silicon chip 5. Finally, mix hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% according to the mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 for 3 minutes to remove the metal on the silicon wafer 5 tarnish;

Step 3: then make four aluminum films 7 as sacrificial layers to the bottom surface of the silicon wafer 5 by metal sputtering, so that the silicon wafer 5 with the aluminum films 7 is formed, and the thickness of each aluminum film 7 is 500nm, the positions of all aluminum films are on the bottom surface of the silicon wafer 5 and in the longitudinal projection of the edge of the preset suspended micro-sensitive structure 51 as shown in Figure 4;

Step 4: Clean the silicon chip 5 with the aluminum film 7 with a mixed solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 3 minutes to remove the organic matter on the silicon chip 5, and then treat the ammonia water with a mass concentration of 60%, Hydrogen peroxide and pure water were mixed according to the mass ratio of 1:1:5, and the silicon wafer 5 with the aluminum film 7 was cleaned for 3 minutes with the mixed solution to remove the non-metallic contamination on the silicon wafer 5, and finally with a mass concentration of 30 % hydrochloric acid, hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the silicon wafer 5 with the aluminum film 7 is cleaned for 3 minutes with the mixed solution to remove metal contamination on the silicon wafer 5; then Bottom glass-silicon electrostatic bonding, that is, the silicon chip 5 with the aluminum film 7 and the bottom glass 2 with the electrode 41 are in contact together, and in order from left to right, the electrode leads on the bottom surface of the silicon chip 5 The shallow grooves 6 are in turn opposed to the corresponding electrode grooves 3 in the bottom glass 2 one by one, and then a DC voltage of 800V is applied at 350 degrees Celsius, the silicon chip 5 is connected to the positive pole of the DC power supply, the bottom glass 2 is connected to the negative pole of the DC power supply, and the The bonding is completed after 25 minutes of DC voltage;

Step 5: After the bottom glass-silicon is electrostatically bonded, the thickness of the silicon wafer 5 is uniformly etched from its upper end to 100 μm by using a tetramethylammonium hydroxide TMAH etching solution with a mass concentration of 25%, and then using a mass concentration of 25% phosphating solution is used to polish the silicon wafer 5, and the polishing time is 3 minutes;

Step 6: Reactive ion etching (RIE) is used to etch the upper surface of the silicon wafer 5 to form more than one electrode lead shallow groove 6, the depth of which is 5 μm, and in order from left to right, on the silicon wafer 5 The electrode lead shallow grooves 6 on the surface can successively accommodate the leads 42 in the corresponding electrode grooves 3 in the top glass 1 one by one, and the protruding planes between each adjacent electrode lead shallow grooves 6 constitute a bonding table 52; Cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer 5 for 3 minutes to remove the organic matter on the silicon wafer 5, and then use a mass concentration of 60% ammonia water, hydrogen peroxide and pure water according to the mass concentration. The ratio of 1: 1: 5 was mixed, and the silicon chip 5 was cleaned for 3 minutes with the mixed solution to remove the non-metallic pollution on the silicon chip 5, and finally the hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% were used according to the mass ratio of 1 : 1:5, and the silicon wafer 5 was cleaned for 3 minutes with the mixed solution to remove metal contamination on the silicon wafer 5;

Step 7: Then adopt the inductively coupled plasma ICP dry method, respectively place the electrode groove 3 along the edge of the preset floating micro-sensitive structure 51 and the edge of the electrode groove 3 with the outwardly extending lead groove 60 on the outside of the bottom glass 2. The silicon wafer 5 is carved vertically without penetrating the aluminum film 7 to form a suspended micro-sensing structure 51 and conductive silicon 54. The other parts of the silicon wafer are bulk silicon 53, and the bulk silicon 53 passes through the aluminum film 7 and the suspended micro-sensing structure 51. In addition, grooves 8 are carved laterally on the side of the bulk silicon 53, thus forming a bottom glass-silicon chip assembly with a suspended micro-sensitive structure 51 and conductive silicon 54, as shown in Figure 5, Figure 6 and Figure 7 shown;

Step 8: Clean the underlying glass-silicon chip combination with a solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 3 minutes to remove the organic matter on it, and then wash it with 60% ammonia water, hydrogen peroxide and pure Water is mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon chip assembly sheet is cleaned with the mixed solution for 3 minutes to remove the non-metallic contamination on it, and finally with 30% mass concentration of hydrochloric acid, hydrogen peroxide and Pure water is mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer assembly is cleaned with the mixed solution for 3 minutes to remove the metal contamination on it; then the top glass-silicon electrostatic bonding is carried out, that is, The bottom glass-silicon chip combination sheet is in contact with the top glass 1 with electrodes 41, and in the order from left to right, the electrode lead shallow grooves 6 on the upper surface of the silicon chip 5 are connected to the top glass 1 one by one. The corresponding electrode grooves 3 are facing each other, and then a DC voltage of 800V is applied at 350 degrees Celsius. The bulk silicon 53 is connected to the positive pole of the DC power supply, and the top glass 1 is connected to the negative pole of the DC power supply. After the DC voltage is turned on for 25 minutes, the bonding is completed to obtain three layers. combination piece;

Step 9: immerse the three-layer composite sheet in an aluminum etchant, and ultrasonically clean it for 20 minutes to remove the aluminum film 7 as a sacrificial layer. The aluminum etchant is composed of phosphoric acid with a mass concentration of 85% and a mass concentration of 70% nitric acid, acetic acid and water are mixed according to volume percentage of 10%, 0.5%, 9.5% and 80% respectively;

Step 10: Immediately take the three-layer composite chip out of the aluminum etchant, wash it with clean water for 20 minutes in an ultrasonic environment, and replace it with suspended micro-sensitive structure 51, conduction silicon 54 and bulk silicon 53 inside the structure The remaining reactants and aluminum etchant were cleaned with ethanol for 10 minutes in an ultrasonic environment to replace water, thus completing the preparation of the suspended micro-sensitive structure based on the aluminum sacrificial layer process, as shown in Figure 8.

Example 2:

The preparation method of the suspended micro-sensitive structure based on the aluminum sacrificial layer technology in this embodiment, the steps are as follows:

Step 1: Etch three 140nm-deep electrode grooves 3 on the surface of the top glass 1 and the bottom glass 2 respectively with buffered hydrofluoric acid BHF wet method, each electrode groove 3 has an outwardly extending Lead groove 60, and in order from left to right, the size and longitudinal position of each pair of electrode grooves 3 corresponding to the top glass 1 and the bottom glass 2 are consistent, and each pair of electrode grooves 3 constitutes a differential electrode groove groove, and then sputter 190nm thick titanium gold alloy in each electrode groove 3 to form four electrodes 41, and sputter outwardly extending leads 42 into the corresponding electrode groove 3 on the outer side of each electrode 41 lead groove 60, the width of each lead 42 is 40 μm, and the interval between adjacent lead 42 is 20 μm, so just obtain the top glass 1 with electrode 41 and the bottom glass 2 with electrode 41, and each pair The number, size and position of the electrodes 41 and their lead wires 42 in the differential electrode groove 3 are also correspondingly consistent, and each pair of correspondingly consistent electrodes 41 and their lead wires 42 constitute a differential electrode 4 as shown in Figures 1, 2 and Fig. 3 shown;

Step 2: Use an n-type crystal-oriented single-crystal silicon wafer 5 with a resistivity of 0.002Ω·cm, perform standard cleaning, and etch the bottom surface of the silicon wafer 5 by inductively coupled plasma ICP dry method to form three electrodes Lead wire shallow groove 6, its depth is 7 μ m, and according to the order from left to right, the electrode lead wire shallow groove 6 on the bottom surface of silicon chip 5 can accommodate the lead wire 42 in the corresponding electrode groove 3 in the bottom glass 2 one by one, and The protruding plane between each adjacent electrode lead shallow groove 6 constitutes the bonding table top 52; wherein the standard cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer 5 for 4 minutes. Remove the organic matter on the silicon wafer 5, then mix the ammonia water, hydrogen peroxide and pure water with a concentration of 60% according to the mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 for 4 minutes to remove the silicon wafer 5. Finally, mix hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% according to the mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 for 4 minutes to remove the metal on the silicon wafer 5 tarnish;

Step 3: then make four aluminum films 7 as sacrificial layers to the bottom surface of the silicon wafer 5 by metal sputtering, so that the silicon wafer 5 with the aluminum films 7 is formed, and the thickness of each aluminum film 7 is 700nm, the positions of all aluminum films are on the bottom surface of the silicon wafer 5 and in the vertical projection of the edge of the preset suspended micro-sensitive structure 51 as shown in Figure 4;

Step 4: Clean the silicon wafer 5 with the aluminum film 7 with a mixed solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 4 minutes to remove the organic matter on the silicon wafer 5, and then treat the ammonia water with a mass concentration of 60%, Hydrogen peroxide and pure water were mixed according to the mass ratio of 1:1:5, and the silicon wafer 5 with the aluminum film 7 was cleaned for 4 minutes with the mixed solution to remove the non-metallic contamination on the silicon wafer 5, and finally with a mass concentration of 30 % hydrochloric acid, hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the silicon wafer 5 with the aluminum film 7 is cleaned for 4 minutes with the mixed solution to remove metal contamination on the silicon wafer 5; then Bottom glass-silicon electrostatic bonding, that is, the silicon chip 5 with the aluminum film 7 and the bottom glass 2 with the electrode 41 are in contact together, and in order from left to right, the electrode leads on the bottom surface of the silicon chip 5 The shallow grooves 6 are in turn opposed to the corresponding electrode grooves 3 in the bottom glass 2 one by one, and then a DC voltage of 1000V is applied at 400 degrees Celsius, the silicon wafer 5 is connected to the positive pole of the DC power supply, the bottom glass 2 is connected to the negative pole of the DC power supply, and the The bonding is completed after 28 minutes of DC voltage;

Step 5: After the bottom glass-silicon is electrostatically bonded, the thickness of the silicon wafer 5 is uniformly etched from its upper end to 100 μm by using a tetramethylammonium hydroxide TMAH etching solution with a mass concentration of 25%, and then using a mass concentration of 25% phosphating solution is used to polish the silicon wafer 5, and the polishing time is 5 minutes;

Step 6: Reactive ion etching (RIE) is used to etch the upper surface of the silicon wafer 5 to form more than one electrode lead shallow groove 6, the depth of which is 8 μm, and in order from left to right, on the silicon wafer 5 The electrode lead shallow grooves 6 on the surface can successively accommodate the leads 42 in the corresponding electrode grooves 3 in the top glass 1 one by one, and the protruding planes between each adjacent electrode lead shallow grooves 6 constitute a bonding table 52; Cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer 5 for 4 minutes to remove the organic matter on the silicon wafer 5, and then use a mass concentration of 60% ammonia water, hydrogen peroxide and pure water according to the mass concentration. The ratio of 1: 1: 5 was mixed, and the silicon wafer 5 was cleaned for 4 minutes with the mixed solution to remove the non-metallic contamination on the silicon wafer 5, and finally the hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% were used according to the mass ratio of 1 : 1:5, the silicon wafer 5 was cleaned for 4 minutes with the mixed solution to remove metal contamination on the silicon wafer 5;

Step 7: Then adopt the inductively coupled plasma ICP dry method, respectively place the electrode groove 3 along the edge of the preset floating micro-sensitive structure 51 and the edge of the electrode groove 3 with the outwardly extending lead groove 60 on the outside of the bottom glass 2. The silicon wafer 5 is carved vertically without penetrating the aluminum film 7 to form a suspended micro-sensing structure 51 and conductive silicon 54. The other parts of the silicon wafer are bulk silicon 53, and the bulk silicon 53 passes through the aluminum film 7 and the suspended micro-sensing structure 51. In addition, grooves 8 are carved laterally on the side of the bulk silicon 53, thus forming a bottom glass-silicon chip assembly with a suspended micro-sensitive structure 51 and conductive silicon 54, as shown in Figure 5, Figure 6 and Figure 7 shown;

Step 8: Clean the bottom glass-silicon chip combination with a solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 4 minutes to remove the organic matter on it, and then wash it with 60% ammonia water, hydrogen peroxide and pure Water is mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon chip assembly sheet is cleaned with the mixed solution for 4 minutes to remove the non-metallic contamination on it, and finally with 30% mass concentration of hydrochloric acid, hydrogen peroxide and Pure water is mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer assembly is cleaned with the mixed solution for 4 minutes to remove the metal contamination on it; then the top glass-silicon electrostatic bonding is carried out, that is, The bottom glass-silicon chip combination sheet is in contact with the top glass 1 with electrodes 41, and in the order from left to right, the electrode lead shallow grooves 6 on the upper surface of the silicon chip 5 are connected to the top glass 1 one by one. The corresponding electrode grooves 3 are facing each other, and then a DC voltage of 1000V is applied at 400 degrees Celsius. The bulk silicon 53 is connected to the positive pole of the DC power supply, and the top glass 1 is connected to the negative pole of the DC power supply. After 28 minutes of connecting the DC voltage, the bonding is completed to obtain three layers. combination piece;

Step 9: immerse the three-layer composite sheet in an aluminum etchant, and ultrasonically clean it for 20 minutes to remove the aluminum film 7 as a sacrificial layer. The aluminum etchant is composed of phosphoric acid with a mass concentration of 85% and a mass concentration of 70% nitric acid, acetic acid and water are mixed according to volume percentage of 15%, 0.5%, 4.5% and 80% respectively;

Step 10: Immediately take the three-layer composite chip out of the aluminum etchant, wash it with clean water for 20 minutes in an ultrasonic environment, and replace it with suspended micro-sensitive structure 51, conduction silicon 54 and bulk silicon 53 inside the structure The remaining reactants and aluminum etchant were cleaned with ethanol for 10 minutes in an ultrasonic environment to replace water, thus completing the preparation of the suspended micro-sensitive structure based on the aluminum sacrificial layer process, as shown in Figure 8.

Example 3:

The preparation method of the suspended micro-sensitive structure based on the aluminum sacrificial layer technology in this embodiment, the steps are as follows:

Step 1: Etch three 155nm-deep electrode grooves 3 on the surface of the top glass 1 and the bottom glass 2 respectively with buffered hydrofluoric acid BHF wet method, and the outer side of each electrode groove 3 has an outwardly extending Lead groove 60, and in order from left to right, the size and longitudinal position of each pair of electrode grooves 3 corresponding to the top glass 1 and the bottom glass 2 are consistent, and each pair of electrode grooves 3 constitutes a differential electrode groove groove, and then sputter 205nm thick titanium gold alloy in each electrode groove 3 to form four electrodes 41, and sputter outwardly extending leads 42 into the corresponding electrode groove 3 on the outer side of each electrode 41 lead groove 60, the width of each lead 42 is 45 μm, and the interval between adjacent lead 42 is 25 μm, so just obtain the top glass 1 with electrode 41 and the bottom glass 2 with electrode 41, and each pair The number, size and position of the electrodes 41 and their lead wires 42 in the differential electrode groove 3 are also correspondingly consistent, and each pair of correspondingly consistent electrodes 41 and their lead wires 42 constitute a differential electrode 4 as shown in Figures 1, 2 and Fig. 3 shown;

Step 2: Use an n-type crystal-oriented monocrystalline silicon wafer 5 with a resistivity of 0.003Ω·cm, perform standard cleaning, and etch the bottom surface of the silicon wafer 5 by inductively coupled plasma ICP dry method to form three electrodes Lead wire shallow groove 6, its depth is 9 μm, and according to the order from left to right, the electrode lead wire shallow groove 6 on the bottom surface of silicon wafer 5 can accommodate the lead wire 42 in the corresponding electrode groove 3 in the bottom glass 2 one by one, and The protruding plane between each adjacent electrode lead shallow groove 6 constitutes the bonding table top 52; wherein the standard cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer 5 for 5 minutes. Remove the organic matter on the silicon wafer 5, then mix ammonia water, hydrogen peroxide, and pure water with a mass concentration of 60% in a mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 for 5 minutes to remove the silicon wafer 5. For non-metallic contamination on the surface, finally mix hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% according to the mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer 5 for 5 minutes to remove the silicon wafer 5 metal contamination on

Step 3: then make four aluminum films 7 as sacrificial layers to the bottom surface of the silicon wafer 5 by metal sputtering, so that the silicon wafer 5 with the aluminum films 7 is formed, and the thickness of each aluminum film 7 is 900nm, the positions of all aluminum films are on the bottom surface of the silicon wafer 5 and in the longitudinal projection of the edge of the preset suspended micro-sensitive structure 51 as shown in Figure 4;

Step 4: Clean the silicon wafer 5 with the aluminum film 7 with a mixed solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 4 minutes to remove the organic matter on the silicon wafer 5, and then treat the ammonia water with a mass concentration of 60%, Hydrogen peroxide and pure water were mixed according to the mass ratio of 1:1:5, and the silicon wafer 5 with the aluminum film 7 was cleaned for 4 minutes with the mixed solution to remove the non-metallic contamination on the silicon wafer 5, and finally with a mass concentration of 30 % hydrochloric acid, hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the silicon wafer 5 with the aluminum film 7 is cleaned for 4 minutes with the mixed solution to remove metal contamination on the silicon wafer 5; then Bottom glass-silicon electrostatic bonding, that is, the silicon chip 5 with the aluminum film 7 and the bottom glass 2 with the electrode 41 are in contact together, and in order from left to right, the electrode leads on the bottom surface of the silicon chip 5 The shallow grooves 6 are opposed to the corresponding electrode grooves 3 in the bottom glass 2 one by one, and then a DC voltage of 1300V is applied at 420 degrees Celsius. The silicon wafer 5 is connected to the positive pole of the DC power supply, and the bottom glass 2 is connected to the negative pole of the DC power supply. The bonding is completed after 29 minutes of DC voltage;

Step 5: After the bottom glass-silicon is electrostatically bonded, the thickness of the silicon wafer 5 is uniformly etched from its upper end to 100 μm by using a tetramethylammonium hydroxide TMAH etching solution with a mass concentration of 25%, and then using a mass concentration of 25% phosphating solution is used to polish the silicon wafer 5, and the polishing time is 6 minutes;

Step 6: Reactive ion etching (RIE) is used to etch the upper surface of the silicon wafer 5 to form more than one electrode lead shallow groove 6, the depth of which is 8 μm, and in order from left to right, on the silicon wafer 5 The electrode lead shallow grooves 6 on the surface can successively accommodate the leads 42 in the corresponding electrode grooves 3 in the top glass 1 one by one, and the protruding planes between each adjacent electrode lead shallow grooves 6 constitute a bonding table 52; Cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer 5 for 4 minutes to remove the organic matter on the silicon wafer 5, and then use a mass concentration of 60% ammonia water, hydrogen peroxide and pure water according to the mass concentration. The ratio of 1: 1: 5 was mixed, and the silicon wafer 5 was cleaned for 4 minutes with the mixed solution to remove the non-metallic contamination on the silicon wafer 5, and finally the hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% were used according to the mass ratio of 1 : 1:5, the silicon wafer 5 was cleaned for 4 minutes with the mixed solution to remove metal contamination on the silicon wafer 5;

Step 7: Then adopt the inductively coupled plasma ICP dry method, respectively place the electrode groove 3 along the edge of the preset floating micro-sensitive structure 51 and the edge of the electrode groove 3 with the outwardly extending lead groove 60 on the outside of the bottom glass 2. The silicon wafer 5 is carved vertically without penetrating the aluminum film 7 to form a suspended micro-sensing structure 51 and conductive silicon 54. The other parts of the silicon wafer are bulk silicon 53, and the bulk silicon 53 passes through the aluminum film 7 and the suspended micro-sensing structure 51. In addition, grooves 8 are carved laterally on the side of the bulk silicon 53, thus forming a bottom glass-silicon chip assembly with a suspended micro-sensitive structure 51 and conductive silicon 54, as shown in Figure 5, Figure 6 and Figure 7 shown;

Step 8: Wash the bottom glass-silicon chip combination with a solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 4 minutes to remove the organic matter on it, and then wash it with 60% ammonia water, hydrogen peroxide and Pure water is mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer composite sheet is cleaned with the mixed solution for 4 minutes to remove the non-metallic contamination on it, and finally the hydrochloric acid and hydrogen peroxide with a mass concentration of 30% and pure water are mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer assembly is cleaned with the mixed solution for 4 minutes to remove the metal contamination on it; then the top glass-silicon electrostatic bonding is carried out, That is to say, the bottom glass-silicon wafer composite sheet is in contact with the top glass 1 with electrodes 41, and in order from left to right, the electrode lead shallow grooves 6 on the upper surface of the silicon wafer 5 are successively connected to the top glass 1 one by one. The corresponding electrode grooves 3 are opposite to each other, and then a DC voltage of 1000V is applied at 400 degrees Celsius. The bulk silicon 53 is connected to the positive pole of the DC power supply, and the top glass 1 is connected to the negative pole of the DC power supply. After 28 minutes of connecting the DC voltage, the bonding is completed to obtain three Layered combination sheet;

Step 9: immerse the three-layer composite sheet in an aluminum etchant, and ultrasonically clean it for 20 minutes to remove the aluminum film 7 as a sacrificial layer. The aluminum etchant is composed of phosphoric acid with a mass concentration of 85% and a mass concentration of 70% nitric acid, acetic acid and water are mixed according to volume percentage of 15%, 0.5%, 4.5% and 80% respectively;

Step 10: Immediately take the three-layer composite chip out of the aluminum etchant, wash it with clean water for 20 minutes in an ultrasonic environment, and replace it with suspended micro-sensitive structure 51, conduction silicon 54 and bulk silicon 53 inside the structure The remaining reactants and aluminum etchant were cleaned with ethanol for 10 minutes in an ultrasonic environment to replace water, thus completing the preparation of the suspended micro-sensitive structure based on the aluminum sacrificial layer process, as shown in Figure 8.

According to the preparation method of the suspended micro-sensitive structure based on the aluminum sacrificial layer process in Example 1, Example 2 and Example 3, after the bottom glass-silicon is electrostatically bonded, before the suspended micro-sensitive structure 51 is processed on the silicon wafer 5 , the introduction of the aluminum film 7 as a sacrificial layer can connect the suspended micro-sensitive structure 51 and the bulk silicon 53 together. On the one hand, it prevents the suspended micro-sensitive structure 51 from falling off during the etching process; During the glass-silicon electrostatic bonding process, an elastic force opposite to the electrostatic force generated by the bonding is provided, so that the suspended micro-sensitive structure 51 is not attracted to the top glass 1 during the bonding process. In addition, the aluminum film 7 serving as the sacrificial layer can be easily removed with an aluminum etchant at the end. In addition, nitric acid in the aluminum etchant oxidizes aluminum into aluminum oxide, and then phosphoric acid dissolves it into phosphate. Acetic acid is mainly used to reduce the surface tension of the corrosion solution, increase the infiltration of the aluminum film surface and the corrosion solution, and improve the corrosion resistance. Uniformity plays a buffer role. This solution effectively ensures the integrity and mobility of the suspended micro-sensitive structure 51 without changing the original process flow, and will not cause performance degradation of the micro-mechanical sensor without increasing mechanical constraints. It can be widely used in the processing of various silicon micro devices with suspended movable sensitive structures.

Claims (1)

1. A method for preparing a suspended micro-sensitive structure based on aluminum sacrificial layer technology, characterized in that the steps are as follows: Step 1: Etch more than one electrode groove (3) with a depth of 120-160nm on the surface of the top glass (1) and the bottom glass (2) respectively with buffered hydrofluoric acid BHF wet method, each electrode groove The outer side of (3) has an outwardly extending lead groove (60), and in order from left to right, the size of each pair of electrode grooves (3) corresponding to the top glass (1) and the bottom glass (2) in turn Consistent with the longitudinal position, each pair of electrode grooves (3) constitutes a differential electrode groove, and then sputters a 170-210nm thick titanium-gold alloy in each electrode groove (3) to form more than one electrode (41), and on the outer surface of each electrode (41), the lead wires (42) extending outwards are sputtered into the lead wire slots (60) of the corresponding electrode grooves (3), and the width of each lead wire (42) is not is less than 30 μm, and the interval between adjacent lead wires (42) is not less than 10 μm, so that the top glass (1) with electrodes (41) and the bottom glass (2) with electrodes (41) are obtained, and each pair The number, size and position of the electrodes (41) and their lead wires (42) in the differential electrode groove (3) are also correspondingly consistent, and each pair of correspondingly consistent electrodes (41) and their lead wires (42) constitute a differential electrode (41) and their lead wires (42). electrode (4); Step 2: Use an n-type or p-type crystal-oriented single-crystal silicon wafer (5) with a resistivity of 0.002-0.004Ω·cm, perform standard cleaning, and use reactive ion etching RIE or inductively coupled plasma ICP dry method Etching is performed on the bottom surface of the silicon wafer (5) to form more than one electrode lead shallow groove (6), the depth of which is 5-10 μm, and in order from left to right, the electrode leads on the bottom surface of the silicon wafer (5) The shallow grooves (6) can successively accommodate the lead wires (42) in the corresponding electrode grooves (3) in the bottom glass (2) one by one, and the protruding planes between each adjacent electrode lead shallow grooves (6) constitute the key combined table top (52); where the standard cleaning is to use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer (5) for 3-5 minutes to remove the organic matter on the silicon wafer (5), and then Mix the ammonia water, hydrogen peroxide and pure water with a mass concentration of 60% according to the mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer (5) for 3-5 minutes to remove the non-toxic impurities on the silicon wafer (5). For metal contamination, mix 30% hydrochloric acid, hydrogen peroxide and pure water in a mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer (5) for 3-5 minutes to remove the silicon wafer (5) metal contamination on Step 3: Next, make more than one aluminum film (7) as a sacrificial layer on the bottom surface of the silicon wafer (5) by metal sputtering, thus forming a silicon wafer (5) with an aluminum film (7) , the thickness of each aluminum film (7) is 500-1000nm, and the position of all aluminum films is on the bottom surface of the silicon wafer (5) and within the longitudinal projection of the edge of the preset suspended micro-sensitive structure (51); Step 4: Clean the silicon wafer (5) with the aluminum film (7) for 3-5 minutes with a mixed solution of 80% pure sulfuric acid and 20% hydrogen peroxide to remove organic matter on the silicon wafer (5), then Mix ammonia water, hydrogen peroxide, and pure water with a mass concentration of 60% in a mass ratio of 1:1:5, and use the mixed solution to clean the silicon wafer (5) with the aluminum film (7) for 3-5 minutes to remove For the non-metallic contamination on the silicon wafer (5), mix hydrochloric acid, hydrogen peroxide, and pure water with a mass concentration of 30% at a mass ratio of 1:1:5, and use the mixed solution to coat the aluminum film (7) The silicon wafer (5) is cleaned for 3-5 minutes to remove metal contamination on the silicon wafer (5); then carry out the bottom glass-silicon electrostatic bonding, that is, the silicon wafer (5) with the aluminum film (7) and the electrode The bottom glass (2) of (41) is in contact together, and according to the order from left to right, the electrode lead shallow grooves (6) on the bottom surface of the silicon wafer (5) are in turn corresponding to the bottom glass (2) one by one. The electrode groove (3) is opposite to each other, and then a DC voltage of 800-1500V is applied at 350-450 degrees Celsius, the silicon wafer (5) is connected to the positive pole of the DC power supply, the bottom glass (2) is connected to the negative pole of the DC power supply, and the DC voltage is turned on After 25 to 30 minutes, the bonding is completed; Step 5: After the bottom glass-silicon is electrostatically bonded, the thickness of the silicon wafer (5) is uniformly etched from the upper end to 100-150 μm by using tetramethylammonium hydroxide TMAH etching solution with a mass concentration of 25%, and then Polishing the silicon wafer (5) with a phosphating solution with a mass concentration of 25%, and the polishing time is 3-6 minutes; Step 6: Etching the upper surface of the silicon wafer (5) by reactive ion etching or inductively coupled plasma dry method to form more than one electrode lead shallow groove (6), the depth of which is 5-10 μm, and according to From left to right, the electrode lead shallow grooves (6) on the upper surface of the silicon wafer (5) can accommodate the lead wires (42) in the corresponding electrode grooves (3) in the top glass (1) one by one, and each phase The protruding plane between the adjacent electrode lead shallow grooves (6) constitutes the bonding table (52); wherein the standard cleaning is to first use a solution of 80% pure sulfuric acid and 20% hydrogen peroxide to clean the silicon wafer (5) Clean for 3-5 minutes to remove the organic matter on the silicon wafer (5), then mix ammonia, hydrogen peroxide and pure water with a mass concentration of 60% according to the mass ratio of 1:1:5, and use the mixed solution to place the silicon wafer ( 5) Wash for 3-5 minutes to remove non-metallic contamination on the silicon wafer (5), and finally mix hydrochloric acid, hydrogen peroxide and pure water with a mass concentration of 30% according to the mass ratio of 1:1:5, and use the mixed solution Cleaning the silicon wafer (5) for 3-5 minutes to remove metal contamination on the silicon wafer (5); Step 7: Then adopt the inductively coupled plasma ICP dry method, respectively along the edge of the preset suspended micro-sensitive structure (51) and the outer side of the bottom glass (2) with the electrode recesses extending outwards with the lead groove (60) The edge of the groove (3) vertically cuts through the silicon wafer (5) without penetrating the aluminum film (7) to form a suspended micro-sensitive structure (51) and conductive silicon (54), and the other parts of the silicon wafer are bulk silicon (53), the bulk silicon (53) is connected to the suspended micro-sensing structure (51) through the aluminum film (7), and in addition, grooves (8) are carved laterally on the side of the bulk silicon (53), forming a band A bottom glass-silicon wafer combination sheet having a suspended micro-sensitive structure (51) and conducting silicon (54); Step 8: Wash the bottom glass-silicon wafer combination sheet with a solution of 80% pure sulfuric acid and 20% hydrogen peroxide for 3-5 minutes to remove organic matter on it, and then treat the ammonia water with a mass concentration of 60%, Hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer composite sheet is cleaned with the mixed solution for 3-5 minutes to remove the non-metallic contamination on it, and finally, the mass concentration is 30%. Hydrochloric acid, hydrogen peroxide and pure water are mixed according to the mass ratio of 1:1:5, and the bottom glass-silicon wafer assembly sheet is cleaned with the mixed solution for 3-5 minutes to remove the metal contamination on it; then the top glass -Silicon electrostatic bonding, that is, the bottom glass-silicon wafer composite sheet and the top glass (1) with electrodes (41) are in contact together, and in order from left to right, the upper surface of the silicon wafer (5) The electrode lead shallow grooves (6) face the corresponding electrode grooves (3) in the top glass (1) one by one, and then apply a DC voltage of 800-1500V at 350-450 degrees Celsius, and the bulk silicon (53) is connected to a DC power supply Positive electrode, top glass (1) connected to the negative electrode of the DC power supply, and the bonding is completed after the DC voltage is switched on for 25 to 30 minutes to obtain a three-layer composite sheet; Step 9: immerse the three-layer composite sheet in an aluminum etchant, and ultrasonically clean it for 20 to 30 minutes to remove the aluminum film (7) as a sacrificial layer. The aluminum etchant is made of phosphoric acid with a mass concentration of 85%. 1. Nitric acid, acetic acid and water with a mass concentration of 70% are mixed according to volume percentages of 10-30%, 0.5-2%, 5-10% and 60-80% respectively; Step 10: Immediately take the three-layer composite chip out of the aluminum etchant, wash it with clean water for 20 to 30 minutes in an ultrasonic environment, and replace it with a suspended microsensitive structure (51) and conductive silicon (54) As well as the residual reactants and aluminum etchant inside the bulk silicon (53) structure, and then wash it with ethanol for 10 to 30 minutes in an ultrasonic environment to replace the water, thus completing the suspended micro-sensitive structure based on the aluminum sacrificial layer process preparation.

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