CN107607098B - Preparation method of chip-level MEMS (micro-electromechanical systems) rotation modulation gyroscope - Google Patents
Preparation method of chip-level MEMS (micro-electromechanical systems) rotation modulation gyroscope Download PDFInfo
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Abstract
The invention relates to a preparation method of an MEMS rotation modulation gyro chip, belonging to the fields of inertia technology and Micro Electro Mechanical Systems (MEMS). The MEMS rotary modulation gyroscope and the rotary modulation platform are integrally processed by the micro-nano processing method in the preparation process, the defects of large volume, heavy weight, complex assembly and the like of the original rotary modulation gyroscope are overcome, and the MEMS rotary modulation gyroscope obtained by the preparation method has the characteristics of small volume, no assembly, batch manufacturing and the like, and the volume of the MEMS rotary modulation gyroscope is only a few cubic millimeters.
Description
Belongs to the field of:
the invention relates to a preparation method of an MEMS rotation modulation gyro chip, which is used for measuring the rotation angular rate of an object and acquiring the attitude information of the object and belongs to the fields of inertia technology and Micro Electro Mechanical Systems (MEMS).
Background art:
the gyroscope is an inertial device for measuring the rotation angular rate of an object, and has important application in the fields of navigation guidance, platform stability control, automobile industry, consumer electronics and the like. The output drift stability of the gyroscope is a key factor influencing the error of the inertial navigation system. At present, the method for modulating the output drift of the gyroscope by using the rotating platform is an effective and quick method for obviously reducing the attitude error of the navigation system, and becomes an important research direction of the inertial navigation system.
In "ASelf-alignment Method for Non-orthogonal angles of Gimbals in Tri-axis Rotational inertia Navigation System" and "ASelf-alignment Method for Tri-axis Rotational inertia Navigation System" reported by Gao Pengyu et al, as shown in FIG. 1, the output drift of a rotating modulation commercial micro-mechanical gyroscope (Inertial measurement unit) of a motor is utilized to significantly reduce the attitude error of the Inertial System, however, the conventional assembly Method of the motor, the rotating frame and the gyroscope makes the volume of the rotating modulation System almost reach the cubic meter level, meanwhile, the System has the problems of high installation difficulty and assembly precision requirement, while the processing and assembly Method based on the MEMS technology has the characteristics of small volume, high alignment precision, mass production and the like, and can effectively overcome the problems existing in the conventional rotating modulation gyroscope preparation process, and at present, the preparation method of the chip-scale MEMS rotary modulation gyroscope is not reported in literature.
The invention content is as follows:
the invention provides a preparation method of a chip-level MEMS (micro-electromechanical systems) rotation modulation gyroscope.
The chip-level MEMS rotation modulation gyroscope structure is shown in FIGS. 2 and 3: the device layer of the SOI silicon wafer forms a micromechanical gyroscope 14, a lead group 15 and a detection electrode group 16, wherein the lead group 15 comprises a plurality of leads, each lead is connected with the detection electrode, the substrate layer of the SOI silicon chip forms a rotary modulation platform, the rotary modulation platform comprises a rotary flat plate 17, a torsion beam 18 and a rotary flat plate electrode 19, wherein the lower surface of the rotary modulation platform, the first metal electrode 12 and the second metal electrode 13 respectively form a parallel plate capacitor, the rotary plate 17 is used for supporting the micromechanical gyroscope 14, the rotary plate 17 is axially symmetrical along the torsion beam 18, the centroid of the rotary plate 17 coincides with the centroid, meanwhile, the axial direction of the torsion beam 18 is vertical to the angular velocity sensitive axis of the micro-mechanical gyroscope 14, the lower surface of the rotating plate electrode 19 and the upper surface of the glass sheet 1 form a whole through a bonding process, and the lower surface of the rotating plate electrode 19 and the lower surface of the rotating plate 17 have a height difference.
Referring to fig. 4, according to fig. 2 and 4, the preparation process includes the following steps:
a first step of cleaning a glass sheet 1 as shown in FIG. 4 (a); coating a photoresist 2 on the upper surface of the glass sheet 1, wherein the thickness of the photoresist 2 is 200nm to 800 nm;
step two, as shown in fig. 4(b), performing photolithography and development, and sputtering a metal layer 7 on the surface of the photoresist 2, wherein the metal layer 7 should have good conductivity, such as metal copper, platinum, gold, etc., and the thickness of the metal layer 7 is 100nm-300 nm;
thirdly, as shown in fig. 4(c), cleaning the SOI wafer 3, and performing ICP dry etching on the substrate layer 4 of the SOI wafer 3, wherein the etching depth is 5 μm to 100 μm, the substrate layer 4 is silicon, a step is obtained on the substrate layer 4 of the SOI wafer 3, and the step area is larger than 200 μm × 200 μm;
fourthly, as shown in fig. 4(d), the photoresist 2 on the upper surface of the glass sheet 1 is removed to obtain a first metal electrode 12 and a second metal electrode 13; cleaning the SOI wafer 3, and bonding the step and the glass sheet 1 together by a silicon-glass bonding process;
fifthly, as shown in fig. 4(e), coating a photoresist 6 on the upper surface of the device layer 5 of the SOI wafer 3, wherein the thickness of the photoresist 6 is 200nm to 800nm, and the material of the device layer 5 is silicon; then, photoetching and developing are carried out, a metal layer 7 is sputtered on the surface of the photoresist 6, the metal layer 7 has good conductivity, such as metal copper, platinum, gold and the like, and the thickness of the metal 7 is 100nm-300 nm;
sixthly, as shown in fig. 4(f), removing the photoresist on the surface of the device layer 5 to obtain a lead electrode of the gyroscope structure;
seventhly, as shown in fig. 4(g), coating a photoresist 8 on the surface of the device layer 5 sputtered with the metal layer 7, wherein the thickness of the photoresist 8 is 200nm to 800 nm; then, photoetching and developing are carried out, and dry etching is carried out on the device layer 5, wherein the etching depth is the thickness of the device layer 5;
eighthly, as shown in fig. 4(h), removing the photoresist, and removing the oxide layer 9 of the SOI wafer 3 by using a hydrofluoric acid solution, wherein the oxide layer 9 is made of silicon dioxide, so as to form a micromechanical gyroscope 14, a lead group 15 and a detection electrode group 16;
ninth, as shown in fig. 4(i), a photoresist 10 is coated on the surface of the device layer 5, and the thickness of the photoresist is 10 μm to 12 μm; since the thickness of the substrate layer 4 is significantly greater than that of the device layer 5, in order to prevent the device layer 5 from being etched due to failure of the photoresist 10 when the substrate layer 4 is etched, the step requires that the method for coating the photoresist is different from a common coating method, and the ratio, coating flow rate and coating speed of the photoresist need to be controlled, so that the thickness and uniformity of the photoresist meet the requirements, therefore, the conventional spin-coating photoresist is adjusted to be a special spray coating mode, and the parameters for coating the photoresist are controlled as follows: the dilution ratio of the photoresist 10 is 1:11-1:13, the flow rate of the photoresist is controlled to be 2.0mL/min-2.4mL/min, and the moving speed of the nozzle is 110mm/s-130 mm/s;
tenth, as shown in fig. 4(j), performing photolithography and development, and performing dry etching on the substrate layer 4 to an etching depth equal to the thickness of the substrate layer 4, to obtain a rotary modulation platform, which includes a rotary plate, a torsion beam, and a rotary plate electrode; in the step, the characteristic dimension of the etched substrate layer 4 is obviously larger than that of the device layer 5, and meanwhile, the protective capability of the photoresist 10 on the device layer 5 is limited, so that the step requires that a dry etching process is different from a common dry etching process, the common dry etching process can prevent the lag effect and the footing effect, and if the common dry etching process is adopted in the step, the photoresist 10 is probably failed, and the device layer 5 cannot be protected, so that the structure is failed. Therefore, the dry process with a large etching rate is adopted in the step, the influence of the lag effect and the footing effect is ignored, and the key process parameters are as follows: the ratio of the etching time to the passivation time is 1.6-2, the pressure value is 15mT-45mT, and the power value is 12W-17W.
And a tenth step, as shown in fig. 4(k), removing the photoresist to finally obtain the chip-scale MEMS rotation modulation gyroscope.
The invention has the beneficial effects that: the MEMS gyroscope and the rotary modulation platform are integrally processed by utilizing a micro-nano processing method, the defects of large volume, heavy weight, complex assembly and the like of the original rotary modulation gyroscope are overcome, and the MEMS rotary modulation gyroscope obtained by the preparation method has the characteristics of small volume, no assembly, batch manufacturing and the like, and the volume is only a few cubic millimeters.
The invention is further illustrated with reference to the following figures and examples.
Drawings
FIG. 1 is a schematic diagram of a prior art rotary modulation micromechanical gyroscope;
FIG. 2 is a schematic diagram of a chip-scale MEMS rotary modulation gyroscope of the present invention;
FIG. 3 is a side view of a rotary modulation gyroscope of the present invention;
FIG. 4 is a flow chart of a spin modulated gyroscope chip fabrication process of the present invention;
in the figure, 1-glass sheet, 2-photoresist, 3-SOI wafer, 4-substrate layer, 5-device layer, 6-photoresist, 7-metal layer, 8-photoresist, 9-oxide layer, 10-photoresist, 11-lead electrode, 12-first metal electrode, 13-second metal electrode, 14-micromechanical gyroscope, 15-lead group, 16-detection electrode group, 17-rotary plate, 18-torsion beam and 19-rotary plate electrode.
The specific implementation mode is as follows:
the preparation process of the chip-level MEMS rotation modulation gyroscope in the embodiment comprises the following steps:
a first step of cleaning a glass sheet 1 as shown in FIG. 4 (a); coating a photoresist 2 on the upper surface of the glass sheet 1, wherein the thickness of the photoresist 2 is 500 nm;
step two, as shown in fig. 4(b), photoetching and developing, sputtering a metal layer 7 on the surface of the photoresist 2, wherein the metal layer 7 is made of gold and has the thickness of 200 nm;
thirdly, as shown in fig. 4(c), cleaning the SOI wafer 3, wherein the crystal direction of the SOI wafer 3 is <110>, performing ICP dry etching on the substrate layer 4 of the SOI wafer 3, wherein the etching depth is 10 μm, and obtaining a step, wherein the step area is 500 μm × 500 μm;
fourthly, as shown in fig. 4(d), the photoresist 2 on the upper surface of the glass sheet 1 is removed to obtain a metal electrode 12 and a metal electrode 13; cleaning the SOI wafer 3, and bonding the step and the glass sheet 1 together by a silicon-glass bonding process;
fifthly, as shown in fig. 4(e), coating a photoresist 6 on the upper surface of the device layer 5 of the SOI wafer 3, wherein the thickness of the photoresist 6 is 500 nm; then, photoetching and developing are carried out, a metal layer 7 is sputtered on the surface of the photoresist 6, the metal layer 7 is made of gold, and the thickness is 300 nm;
sixthly, as shown in fig. 4(f), removing the photoresist on the surface of the device layer 5 to obtain a lead electrode of the gyroscope structure;
seventhly, as shown in fig. 4(g), coating a photoresist 8 on the surface of the device layer 5 sputtered with the metal layer 7, wherein the thickness is 500 nm; then, photoetching and developing are carried out, and dry etching is carried out on the device layer 5, wherein the etching depth is equal to the thickness of the device layer 5 and is 30 micrometers;
eighthly, as shown in fig. 4(h), removing the photoresist, and removing the oxide layer 9 of the SOI wafer 3 by using a hydrofluoric acid solution to form a micromechanical gyroscope 14, a lead group 15, and a gyroscope drive detection electrode group 16;
ninthly, as shown in fig. 4(i), spraying a photoresist 10 on the surface of the device layer 5 by a spray coating process, wherein the thickness of the photoresist is 11 μm, the dilution ratio of the photoresist 10 is 1:12, the flow rate of the photoresist is 2.2mL/min, and the moving speed of a nozzle is 120 mm/s;
tenth, as shown in fig. 4(j), performing photolithography and development, and performing dry etching on the substrate layer 4, wherein the dry etching parameters are that the ratio of etching time to passivation time is 1.7, the etching time is 10s, the pressure value is 30mT, the power value is 15W, the etching depth is the thickness of the substrate layer 4 and is 400 μm, so as to obtain a rotary modulation platform which comprises a rotary flat plate, a torsion beam and a rotary flat plate electrode;
and a tenth step, as shown in fig. 4(k), removing the photoresist to finally obtain the MEMS rotation modulation gyro chip.
Claims (6)
1. The preparation method of the chip-level MEMS rotation modulation gyroscope is characterized by comprising the following steps of:
firstly, cleaning a glass sheet (1); coating photoresist (2) on the upper surface of the glass sheet (1), wherein the thickness of the photoresist (2) is 200nm to 800 nm;
step two, photoetching and developing, wherein a metal layer (7) is sputtered on the surface of the photoresist (2), and the thickness of the metal layer (7) is 100nm-300 nm;
thirdly, cleaning the SOI wafer (3), carrying out ICP dry etching on the substrate layer (4) of the SOI wafer (3), wherein the etching depth is 5 mu m to 100 mu m, the substrate layer (4) is silicon, a step is obtained on the substrate layer (4) of the SOI wafer (3), and the area of the step is more than 200 mu m multiplied by 200 mu m;
fourthly, removing the photoresist (2) on the upper surface of the glass sheet (1) to obtain a first metal electrode (12) and a second metal electrode (13); cleaning the SOI wafer (3), and bonding the step and the glass sheet (1) together by a silicon-glass bonding process;
fifthly, coating photoresist (6) on the upper surface of the device layer (5) of the SOI wafer (3), wherein the thickness of the photoresist (6) is 200nm to 800nm, and the material of the device layer (5) is silicon; then carrying out photoetching and developing, and sputtering a metal layer (7) on the surface of the photoresist (6), wherein the thickness of the metal layer (7) is 100nm-300 nm;
sixthly, removing the photoresist (6) on the surface of the device layer (5) to obtain a lead electrode (11) of the gyroscope structure;
seventhly, coating photoresist (8) on the surface of the device layer (5) sputtered with the metal layer (7), wherein the thickness of the photoresist (8) is 200nm to 800 nm; then, photoetching and developing are carried out, dry etching is carried out on the device layer (5), and the etching depth is the thickness of the device layer (5);
eighthly, removing the photoresist (8), removing an oxide layer (9) of the SOI wafer (3), wherein the oxide layer (9) is made of silicon dioxide, and forming a micro-mechanical gyroscope (14), a lead group (15) and a detection electrode group (16);
coating a photoresist (10) on the surface of the device layer (5), wherein the thickness of the photoresist is 10-12 μm;
tenth, carrying out photoetching and developing, carrying out dry etching on the substrate layer (4), wherein the etching depth is the thickness of the substrate layer (4), and obtaining a rotary modulation platform which comprises a rotary flat plate (17), a torsion beam (18) and a rotary flat plate electrode (19);
and the tenth step, removing the photoresist (10) to finally obtain the chip-level MEMS rotary modulation gyroscope.
2. The method for manufacturing a chip-scale MEMS spinning modulating gyroscope of claim 1 wherein in step two the metal layer (7) is metallic copper, platinum or gold.
3. The method for manufacturing a chip-scale MEMS rotary modulation gyroscope according to claim 1, wherein the material of the metal layer (7) in the fifth step is copper, platinum or gold.
4. The method for fabricating a chip-scale MEMS spinning modulation gyroscope according to claim 1, wherein hydrofluoric acid solution is used to remove the oxide layer (9) of the SOI wafer (3) in the eighth step.
5. The method for manufacturing a chip-scale MEMS spinning modulating gyroscope of claim 1 wherein the coating method in the ninth step is a spray coating method, and the parameters for coating the photoresist are controlled as follows: the dilution ratio of the photoresist (10) is 1:11-1:13, the flow rate of the photoresist is controlled to be 2.0-2.4 mL/min, and the moving speed of the nozzle is 110-130 mm/s.
6. The method for manufacturing a chip-scale MEMS spinning modulating gyroscope of claim 1, wherein the critical process parameters of the dry etching in the step ten are: the ratio of the etching time to the passivation time is 1.6-2, the pressure value is 15mT-45mT, and the power value is 12W-17W.
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