High-performance z-axis accelerometer and method of manufacturing the same

Abstract

The present disclosure provides a high-performance Z-axis accelerometer and a preparation method thereof, which comprises a movable electrode layer and two fixed electrode plates, and the two fixed electrode plates are respectively covered on opposite sides of the movable electrode layer; the movable electrode layer comprises an electrode frame body and two sealing frame bodies, and one sealing frame body is arranged between each fixed electrode plate and the electrode frame body; the movable electrode layer further comprises a cantilever beam and a mass block, the electrode frame body forms a closed frame structure, the cantilever beam and the mass block are located on the inner side of the electrode frame body, the two ends of the cantilever beam are respectively connected with the electrode frame body and the mass block, and there is a gap between each fixed electrode plate and the mass block when the high-performance Z-axis accelerometer is in a non-acceleration state along the Z-axis. By arranging the sealing frame bodies on the double sides of the movable electrode layer, the chip parasitic capacitance can be significantly reduced, and the process reliability can be improved. By reasonably designing the structure of the mass block and the cantilever beam, the chip sensitivity and dynamic response characteristics are balanced, and the impact resistance of the structure is improved.

Description

TECHNICAL FIELD

[0001] Embodiments of the present disclosure belong to the technical field of MEMS devices, and particularly relate to a high-performance Z-axis accelerometer and a preparation method thereof. BACKGROUND

[0002] Micro-electro-mechanical accelerometer is an inertial device based on MEMS (Micro-Electro-Mechanical System) technology, which is used to measure linear motion acceleration of an object. It has the characteristics of small size, high reliability, low cost, and suitability for mass production, and is widely used in consumer electronics, aerospace, automotive, medical devices, weapons and other fields. However, the accelerometer in the prior art has the problems of high chip parasitic capacitance and poor process reliability. SUMMARY

[0003] Embodiments of the present disclosure aim to at least solve one of the technical problems existing in the prior art, and provide a high-performance Z-axis accelerometer and a preparation method thereof.

[0004] A high-performance Z-axis accelerometer is provided in the first aspect of the present disclosure, which comprises an active electrode layer and two fixed electrode plates, and the two fixed electrode plates are respectively covered on opposite sides of the active electrode layer.

[0005] The active electrode layer comprises an electrode frame and two sealing frames, and one sealing frame is arranged between each fixed electrode plate and the electrode frame.

[0006] The active electrode layer further comprises a cantilever beam and a mass block, the electrode frame forms a closed frame structure, the cantilever beam and the mass block are located on the inner side of the electrode frame, the two ends of the cantilever beam are respectively connected to the electrode frame and the mass block, and when the high-performance Z-axis accelerometer is in a non-acceleration state along the Z-axis, there is a gap between each fixed electrode plate and the mass block.

[0007] In some embodiments of the present disclosure, the active electrode layer comprises two cantilever beams and two mass blocks, each mass block is connected to the electrode frame through a corresponding cantilever beam, and the two mass blocks are symmetrically arranged about the lengthwise center line of the electrode frame, and each mass block is symmetrically arranged about the widthwise center line of the electrode frame.

[0008] In some embodiments of the present disclosure, the material of the sealing frame is BF33 glass.

[0009] In some embodiments of the present disclosure, the end face of the sealing frame close to the fixed electrode plate is in the same plane as the end face of the electrode frame close to the fixed electrode plate.

[0010] In some embodiments of the present disclosure, the thickness of the mass is less than the thickness of the electrode frame.

[0011] In some embodiments of the present disclosure, the electrode frame is arranged around the inner ring of the electrode frame, and the outer ring size of the electrode frame is the same as the outer ring size of the sealing frame.

[0012] In some embodiments of the present disclosure, the movable electrode layer includes a movable outer electrode connected to the outer side of the electrode frame, and the fixed electrode plate includes a fixed outer electrode located on the same side of the electrode frame as the movable outer electrode, and the fixed outer electrode is arranged in a spaced manner with the movable outer electrode.

[0013] The second aspect of the present disclosure provides a preparation method of a high-performance Z-axis accelerometer, which is used for preparing the high-performance Z-axis accelerometer of any one of the above-mentioned embodiments, and the method comprises:

[0014] S100: pretreatment of the fixed electrode plate and formation of the fixed outer electrode;

[0015] S200: bonding of the sealing frame of the silicon plate of the movable electrode layer and the BF33 glass, and etching of the electrode frame, the cantilever beam and the mass of the movable electrode layer;

[0016] S300: bonding of the movable electrode layer and the fixed electrode plate on both sides thereof.

[0017] In some embodiments of the present disclosure, S100 comprises:

[0018] S101: uniform coating of the front surface of the silicon wafer;

[0019] S102: photoetching of the silicon wafer to expose the ear platform area;

[0020] S103: dry etching of the ear platform area to form a support base of the fixed outer electrode;

[0021] S104: uniform coating and photoetching of the front surface of the silicon wafer again, sputtering of metal TiAu or metal Al on the support base of the fixed outer electrode to form the fixed outer electrode;

[0022] S105: removing the glue.

[0023] In some embodiments of the present disclosure, S200 comprises:

[0024] S201: photoetching of the silicon wafer on both sides to expose the sealing frame area;

[0025] S202: dry etching of the silicon wafer on both sides, and then removing the photoresist;

[0026] S203: Bonding the silicon wafer to the BF33 glass on both sides;

[0027] S204: Filling the BF33 glass into the recess of the sealing frame by high temperature reflow, forming the sealing frame structure, and then polishing both sides;

[0028] S205: Sputtering the metal M1 layer on both sides of the silicon wafer, and the metal M1 is Cr or Au;

[0029] S206: Patterning the metal M1 layer by wet etching to form the capacitor gap;

[0030] S207: Removing the metal M1, and then patterning the metal M2 layer to expose the mass release area and the ear non-plate area, and the metal M2 is Cr or Au;

[0031] S208: Wet etching the mass release area and the ear non-plate area to a certain depth;

[0032] S209: Patterning the metal M2 layer again to expose the cantilever beam area;

[0033] S210: Continuing to wet etch the mass release area, cantilever beam area, and ear non-plate area to form the cantilever beam, mass, and ear of the movable outer electrode;

[0034] S211: Removing the metal M2 layer on both sides of the silicon wafer;

[0035] S212: Preparing metal on the ear by a stripping process to form the movable outer electrode.

[0036] The high-performance Z-axis accelerometer and the preparation method thereof according to the embodiments of the present disclosure include two fixed electrode plates and a movable electrode layer, the two fixed electrode plates are bonded with opposite sides of the movable electrode layer, specifically, the movable electrode layer includes an electrode frame body and two sealing frame bodies, the two sealing frame bodies are arranged on opposite sides of the electrode frame body, and the two sides of the electrode frame body are bonded with the fixed electrode plates through the corresponding sealing frame bodies, so that the two fixed electrode plates and the electrode frame body form a closed space. By arranging the sealing frame bodies on the double sides of the movable electrode layer, the chip parasitic capacitance can be significantly reduced, the process reliability is improved, and the product engineering mass production is suitable. In addition, the movable electrode layer further includes a cantilever beam and a mass block, the mass block is connected to the inner side of the electrode frame body through the cantilever beam, the movable mass block is anchored through the cantilever beam, the mass block is clamped between the upper and lower fixed electrodes, and a “sandwich” structure is formed. When the high-performance Z-axis accelerometer moves along the sensitive axis (such as the Z-axis) perpendicular to the chip plane, the inertial force causes the mass block to displace, thereby changing the distance between the mass block and the upper and lower fixed electrode plates, resulting in a change in the differential capacitance between the mass block and the fixed electrode plates on both sides. The integrated detection circuit measures the change amount of the pair of differential capacitances, and converts it into an electrical signal (usually voltage) corresponding to the acceleration size and direction output. By reasonably designing the structure of the mass block and the cantilever beam, the chip sensitivity and dynamic response characteristics are balanced, and the impact resistance of the structure is improved. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is an assembly structure diagram of the high-performance Z-axis accelerometer of the present disclosure.

[0038] Figure 2 It is a split structure diagram of the high-performance Z-axis accelerometer shown. Figure 1

[0039] Figure 3 It is a cross-sectional view of the high-performance Z-axis accelerometer shown. Figure 1

[0040] Figure 4 It is a structure diagram of the fixed electrode plate shown. Figure 1

[0041] Figure 5 It is a structure diagram of the movable electrode layer shown. Figure 1

[0042] Figure 6 It is the state and capacitance diagram of the high-performance Z-axis accelerometer shown when acceleration is generated in the Z-axis. Figure 1

[0043] Figure 7 It is a flow chart of the preparation method of the fixed electrode plate of the high-performance Z-axis accelerometer of the present disclosure. Figure 7 ​​​​​(a) is a structural diagram of step S101; Figure 7 (b) is a structural diagram of step S102; Figure 7 (c) is a structural diagram of step S103; Figure 7 (d) is a structural diagram of step S104; Figure 7 (e) is a structural diagram of step S105;

[0044] Figure 8 is Figure 7 a schematic diagram of the fixed electrode plate prepared by the preparation method shown in the figure;

[0045] Figure 9 is a flow chart of a preparation method of a movable electrode layer of a high-performance Z-axis accelerometer of the present application; Figure 9 (a) is a structural diagram of step S201; Figure 9 (b) is a structural diagram of step S202; Figure 9 (c) is a structural diagram of step S203; Figure 9 (d) is a structural diagram of step S204; Figure 9 (e) is a structural diagram of step S205; Figure 9 (f) is a structural diagram of step S206; Figure 9 (g) is a structural diagram of step S207; Figure 9 (h) is a structural diagram of step S208; Figure 9 (i) is a structural diagram of step S209; Figure 9 (j) is a structural diagram of step S210; Figure 9 (k) is a structural diagram of step S211; Figure 10 (l) is a structural diagram of step S212;

[0046] Figures 1 to 6 is a bonding diagram of a high-performance Z-axis accelerometer of the present application.

[0047] In the drawings, each reference numeral represents the following:

[0048] 100, high-performance Z-axis accelerometer;

[0049] 10, fixed electrode plate; 11, fixed outer electrode;

[0050] 20, movable electrode layer; 21, electrode frame; 22, sealing frame; 23, cantilever beam; 24, mass; 25, movable outer electrode. DETAILED DESCRIPTION

[0051] In order for those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be further described in detail below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure and not to limit the disclosure. The described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present disclosure.

[0052] As shown in Figure 6 The first aspect of the present disclosure provides a high-performance Z-axis accelerometer 100, which comprises a movable electrode layer 20 and two fixed electrode plates 10, and the two fixed electrode plates 10 are respectively covered on opposite sides of the movable electrode layer 20.

[0053] The movable electrode layer 20 comprises an electrode frame 21 and two sealing frames 22, and one sealing frame 22 is arranged between each fixed electrode plate 10 and the electrode frame 21. The movable electrode layer 20 further comprises a cantilever beam 23 and a mass block 24, and the electrode frame 21 forms a closed frame structure, the cantilever beam 23 and the mass block 24 are located on the inner side of the electrode frame 21, and the two ends of the cantilever beam 23 are respectively connected to the electrode frame 21 and the mass block 24. When the high-performance Z-axis accelerometer 100 is in a non-acceleration state along the Z-axis, there is a gap between each fixed electrode plate 10 and the mass block 24.

[0054] The high-performance Z-axis accelerometer 100 according to the embodiments of the present disclosure comprises two fixed electrode plates 10 and a movable electrode layer 20, and the two fixed electrode plates 10 are respectively bonded to opposite sides of the movable electrode layer 20. Specifically, the movable electrode layer 20 comprises an electrode frame 21 and two sealing frames 22, and the two sealing frames 22 are respectively arranged on opposite sides of the electrode frame 21. The two sides of the electrode frame 21 are respectively bonded to the fixed electrode plates 10 through the corresponding sealing frames 22, so that the two fixed electrode plates 10 and the electrode frame 21 form a closed space. By arranging the sealing frames 22 on both sides of the movable electrode layer 20, the chip parasitic capacitance can be significantly reduced, the process reliability can be improved, and the product engineering mass production can be applied.

[0055] In addition, the movable electrode layer 20 further comprises a cantilever beam 23 and a mass block 24, and the mass block 24 is connected to the inner side of the electrode frame 21 through the cantilever beam 23. The movable mass block 24 anchored by the cantilever beam 23 is clamped between the upper and lower fixed electrodes, forming a "sandwich" structure. When the high-performance Z-axis accelerometer 100 accelerates along the sensitive axis perpendicular to the chip plane (such as the Z-axis), the mass block 24 will move along the Z-axis, and the cantilever beam 23 will be bent to generate a stress. Figures 7 to 10As shown in FIG. 1, when the acceleration is applied to the MEMS chip, the inertial force causes the mass 24 to displace, thereby changing the distance between the mass 24 and the two fixed electrode plates 10, such as the distance between the mass 24 and one side of the fixed electrode plate 10 increases, and the distance between the mass 24 and the other side of the fixed electrode plate 10 decreases, resulting in a change in the differential capacitance between the mass 24 and the two sides of the fixed electrode plate 10. The integrated detection circuit measures the amount of change in the pair of differential capacitances and converts it into an electrical signal (usually voltage) corresponding to the size and direction of the acceleration. By reasonably designing the structure of the mass 24 and the cantilever beam 23, the sensitivity and dynamic response characteristics of the balance chip are balanced, and the impact resistance of the structure is improved.

[0056] In some embodiments of the present disclosure, the movable electrode layer 20 includes two cantilever beams 23 and two masses 24, each mass 24 is connected to the electrode frame 21 through a corresponding cantilever beam 23, and the two masses 24 are symmetrically arranged about the lengthwise center line of the electrode frame 21, and each mass 24 is symmetrically arranged about the widthwise center line of the electrode frame 21. By arranging two symmetric masses 24, the symmetry of the movable electrode layer 20 can be improved, and the non-uniform stress caused by process errors can be offset, thereby improving the zero bias and temperature stability of the device while reducing the cross-axis sensitivity of the chip.

[0057] In some embodiments of the present disclosure, the sealing frame 22 is made of BF33 glass, the electrode frame 21 made of silicon is bonded to the sealing frame 22 made of BF33 glass, and the fixed electrode plate 10 made of silicon is bonded to the sealing frame 22 made of BF33 glass.

[0058] In some embodiments of the present disclosure, the end surface of the sealing frame 22 near the fixed electrode plate 10 is flush with the end surface of the electrode frame 21 near the fixed electrode plate 10. That is, the movable electrode layer 20 is bonded to the fixed electrode plate 10 through the sealing frame 22.

[0059] In some embodiments of the present disclosure, two sealing frames 22 are respectively embedded into opposite sides of the electrode frame 21 to ensure the reliability of the connection between the electrode frame 21 and the sealing frame 22.

[0060] In some embodiments of the present disclosure, the overall thickness of the embedded structure formed by the two sealing frames 22 and the electrode frame 21 is greater than the thickness of the mass 24, so as to ensure that there is a movable gap between the two sides of the mass 24 and the two fixed electrode plates 10.

[0061] In other embodiments of the present disclosure, a receiving groove capable of accommodating the movement of the mass 24 can also be provided on the fixed electrode plate 10. At this time, the overall thickness of the embedded structure formed by the two sealing frames 22 and the electrode frame 21 can be equal to the thickness of the mass 24.

[0062] In some embodiments of the present disclosure, the electrode frame 21 is arranged around the inner ring of the electrode frame 21, and the outer ring of the electrode frame 21 has the same size as the outer ring of the sealing frame 22, so that the sealing frame 22 can isolate the electrode frame 21 and fix the electrode plate 10, while reducing the volume and weight of the sealing frame 22.

[0063] In some embodiments of the present disclosure, the movable electrode layer 20 includes a movable outer electrode 25 connected to the outer side of the electrode frame 21, and the fixed electrode plate 10 includes a fixed outer electrode 11 located on the same side of the electrode frame 21 as the movable outer electrode 25, and the fixed outer electrode 11 is arranged in a spaced manner with the movable outer electrode 25. Specifically, along the width direction of the electrode frame 21, one fixed outer electrode 11, the movable outer electrode 25, and another fixed outer electrode 11 are arranged in sequence in a spaced manner.

[0064] In embodiments of the present disclosure, the fixed electrode plate 10 is a rectangular plate structure, one side of the fixed electrode plate 10 is provided with a fixed outer electrode 11, and the electrode frame 21 and the sealing frame 22 are both rectangular frame structures, and in a plane perpendicular to the thickness direction of the fixed electrode plate 10, the outer edges of the sealing frame 22 and the electrode frame 21 both coincide with the rectangular edge profile of the fixed electrode plate 10, two fixed electrode plates 10 are respectively covered on two sides of the electrode frame 21, and the two fixed electrode plates 10 are respectively bonded and connected to the electrode frame 21 through two sealing frames 22, so that the two fixed electrode plates 10 and the electrode frame 21 together form a closed space accommodating the mass block 24 and the cantilever beam 23.

[0065] It should be noted that the inner side of the electrode frame 21 refers to one side of the rectangular space surrounded by the rectangular structure frame, and the outer side of the electrode frame 21 refers to the side of the rectangular structure frame facing away from the rectangular space.

[0066] As shown in FIG. 1, Figure 7 The second aspect of the present disclosure provides a preparation method of a high-performance Z-axis accelerometer 100, which is used for preparing the high-performance Z-axis accelerometer 100 of any of the above-mentioned embodiments, and the method comprises:

[0067] S100: pretreatment of the fixed electrode plate 10 and formation of the fixed outer electrode 11;

[0068] S200: bonding of the sealing frame 22 of the silicon plate and the BF33 glass of the movable electrode layer 20, and etching of the electrode frame 21, the cantilever beam 23, and the mass block 24 of the movable electrode layer 20;

[0069] S300: bonding of the movable electrode layer 20 and the fixed electrode plate 10 on both sides of the movable electrode layer 20.

[0070] According to the preparation method of the high-performance Z-axis accelerometer 100, by arranging the sealing frame 22 on both sides of the movable electrode layer 20, the chip parasitic capacitance can be significantly reduced, the process reliability is improved, and the product engineering mass production is suitable. By reasonably designing the structure of the mass block 24 and the cantilever beam 23, the chip sensitivity and dynamic response characteristics are balanced, and the impact resistance of the structure is improved.

[0071] In some embodiments of the present disclosure, S100 includes:

[0072] S101: uniformly glue the front surface of the silicon wafer for preparing the fixed electrode plate 10 (as shown in Figure 7 a);

[0073] S102: photoetching the silicon wafer to expose the Si in the non-polar plate area, that is, the Si in the ear platform area (as shown in Figure 7 b);

[0074] S103: dry etching the exposed Si in the ear platform area to form a silicon support base of the fixed outer electrode 11, that is, the part of the fixed electrode plate 10 prepared by retaining the ear platform area, and the remaining part of the ear platform area is removed (as shown in Figure 8 c) and Figure 7 d);

[0075] S104: uniformly glue the front surface of the silicon wafer again, and sputter metal TiAu or metal Al on the fixed outer electrode 11 to form a metal layer on the silicon support base, that is, to form the fixed outer electrode (as shown in Figure 7 d);

[0076] S105: remove the glue to obtain the structure of the electrode plate 10 connected with the fixed outer electrode 11 (as shown in Figure 8 e) and Figure 9 f);

[0077] In some embodiments of the present disclosure, S200 includes:

[0078] S201: photoetching and patterning on both sides of the silicon wafer for preparing the movable electrode layer 20 to expose the corresponding area of the sealing frame 22 (as shown in Figure 9 a);

[0079] S202: dry etching the silicon surface to a depth of 90-110 μm, preferably 100 μm, to form an annular groove accommodating the sealing frame 22, and then removing the photoresist (as shown in Figure 9 b);

[0080] S203: anodic bonding of the silicon wafer Si on both sides with the BF33 glass plate (as shown in Figure 9 c);

[0081] S204: BF33 glass high temperature melting reflow filling to the annular groove of the containment frame 22, forming the containment frame 22 structure, and then double-sided grinding and polishing (as shown in Figure 9 d) ;

[0082] S205: double-sided sputtering of the silicon wafer with a metal M1 layer, which is used as a subsequent wet etching hard mask, and the metal M1 is Cr or Au (as shown in Figure 9 e) ;

[0083] S206: patterning the metal M1 layer to expose the area of the non-annular groove, and wet etching the silicon wafer in the non-annular groove area to a depth of 1.5-2.5 μm, preferably 2 μm, to form a capacitor gap (as shown in Figure 9 f) ;

[0084] S207: removing the metal M1, double-sided sputtering of the metal M2 layer, and then patterning to expose the mass release area and the ear non-plate area, and the metal M2 is Cr or Au (as shown in Figure 9 g) ;

[0085] S208: wet etching the mass release area and the ear non-plate area to a certain depth (as shown in Figure 9 h) ;

[0086] S209: patterning the metal M2 layer again to expose the cantilever beam area (as shown in Figure 9 i) ;

[0087] S210: continuing to wet etch the mass release area, the cantilever beam area, and the ear non-plate area to form the cantilever beam 23, the mass 24, and the ear of the movable outer electrode 25 (as shown in Figure 9 j) ;

[0088] S211: removing the metal M2 on both sides (as shown in Figure 9 k) ;

[0089] S212: using a stripping process to prepare a metal in the ear area, which can be TiAu or Al, to form a movable outer electrode (as shown in ​ l).

[0090] It can be understood that the above embodiments are only exemplary embodiments adopted to illustrate the principles of the present disclosure, and the present disclosure is not limited thereto. Various modifications and improvements can be made by those of ordinary skill in the art without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered within the protection scope of the present disclosure.

Claims

1. A high-performance Z-axis accelerometer, characterized in that, The high-performance Z-axis accelerometer includes a movable electrode layer and two fixed electrode plates, with the two fixed electrode plates respectively covering opposite sides of the movable electrode layer; The active electrode layer includes an electrode frame and two sealing frames. Each fixed electrode plate is provided with a sealing frame between itself and the electrode frame. The sealing frame is formed on the electrode frame by high-temperature reflow filling of silicon wafer grooves with BF33 glass. The active electrode layer also includes a cantilever beam and a mass block. The electrode frame forms a closed frame structure. The cantilever beam and the mass block are both located inside the electrode frame. The two ends of the cantilever beam are respectively connected to the electrode frame and the mass block. When the high-performance Z-axis accelerometer is in a non-accelerating state along the Z-axis, there is a gap between each of the fixed electrode plates and the mass block. The active electrode layer includes two cantilever beams and two mass blocks. Each mass block is connected to the electrode frame through a corresponding cantilever beam. The two mass blocks are symmetrically arranged about the centerline of the electrode frame in the length direction and about the centerline of the electrode frame in the width direction.

2. The high-performance Z-axis accelerometer according to claim 1, characterized in that, The end face of the sealing frame near the fixed electrode plate is on the same plane as the end face of the electrode frame near the fixed electrode plate.

3. The high-performance Z-axis accelerometer according to claim 1, characterized in that, The thickness of the mass block is less than the thickness of the electrode frame.

4. The high-performance Z-axis accelerometer according to claim 1, characterized in that, The sealing frame is arranged around the inner ring of the electrode frame, and the outer ring size of the electrode frame is the same as the outer ring size of the sealing frame.

5. The high-performance Z-axis accelerometer according to claim 1, characterized in that, The movable electrode layer includes a movable outer electrode, which is connected to the outside of the electrode frame. The fixed electrode plate includes a fixed outer electrode, which is located on the same side of the electrode frame as the movable outer electrode. The fixed outer electrode and the movable outer electrode are spaced apart.

6. A method for preparing a high-performance Z-axis accelerometer, used to prepare the high-performance Z-axis accelerometer according to any one of claims 1 to 5, characterized in that, The method includes: S100: Pretreatment of the fixed electrode plate and formation of the fixed external electrode; S200: The silicon plate of the active electrode layer is bonded to the sealing frame of BF33 glass. The BF33 glass is reflowed at high temperature to fill the groove of the silicon plate to form a sealing frame structure integrated with the electrode frame. The end face of the sealing frame and the end face of the electrode frame are made to be on the same plane by grinding. Corrosion of the electrode frame, cantilever beam and mass block of the active electrode layer. S300: Bond the active electrode layer and the fixed electrode plates on both sides thereof.

7. The method for preparing a high-performance Z-axis accelerometer according to claim 6, characterized in that, S100 includes: S101: Apply adhesive to the front side of the silicon wafer; S102: Perform photolithography on the silicon wafer to expose the ear area; S103: Dry etching through the earpiece area to form a support base for fixing the external electrode; S104: Photolithography is performed again on the front side of the silicon wafer to sputter metal TiAu or metal Al onto the support substrate for fixing the external electrode to form the fixed external electrode; S105: Remove glue.

8. The method for preparing a high-performance Z-axis accelerometer according to claim 6, characterized in that, S200 includes: S201: Photolithography is performed on both sides of the silicon wafer to pattern the sealing frame area; S202: Dry etching on both sides of the silicon wafer, followed by removal of photoresist; S203: The silicon wafer is bonded to BF33 glass on both sides; S204: BF33 glass is refluxed at high temperature and filled into the groove of the sealing frame to form a sealing frame structure, and then double-sided grinding and polishing are performed. S205: A double-sided sputtered metal M1 layer on a silicon wafer, where the metal M1 is Cr or Au; S206: Patterned metal M1 layer, wet etching to form capacitor gaps; S207: Remove metal M1, pattern the double-sided sputtered metal M2 layer, and expose the mass block release area and the non-electrode area of ​​the earpiece. Metal M2 is Cr or Au. S208: Wet etching of the mass block release area and the non-electrode plate area of ​​the ear platform to a certain depth; S209: Re-pattern the metal M2 layer to expose the cantilever beam area; S210: Continue wet etching of the mass block release area, cantilever beam area and ear platform non-electrode plate area to form the ear platform of cantilever beam, mass block and movable external electrode; S211: Remove the metal M2 layer from both sides of the silicon wafer; S212: Metal is prepared on the earpiece using a stripping process to form a movable external electrode.

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