WO2019019783A1

WO2019019783A1 - Wide-range high-precision double-film-integrated capacitive pressure sensor and preparation method therefor

Info

Publication number: WO2019019783A1
Application number: PCT/CN2018/087790
Authority: WO
Inventors: 秦明; 王振军; 龙克文; 何华娟
Original assignee: 佛山市川东磁电股份有限公司; 东南大学
Priority date: 2017-07-28
Filing date: 2018-05-22
Publication date: 2019-01-31
Also published as: CN107389230B; CN107389230A

Abstract

Disclosed are a wide-range high-precision double-film-integrated capacitive pressure sensor and a preparation method therefor. The pressure sensor comprises a glass substrate (8), wherein a first shallow groove (80) and a second shallow groove (81) are arranged in the glass substrate (8); the first shallow groove (80) is in communication with the second shallow groove (81) by means of a thin groove (82); a central position of the second shallow groove (81) is provided with a shallow groove through-hole (83); the shallow groove through-hole (83) extends to a bottom face of the glass substrate (8) from a bottom face of the second shallow groove (81); the first shallow groove (80) is provided with a capacitor (C1) capable of measuring a low pressure difference; the second shallow groove (81) is provided with a capacitor (C2) capable of measuring a high pressure difference; the capacitor (C1) capable of measuring the low pressure difference comprises a bottom electrode plate (1) and a thin pressure sensitive film (2); the capacitor (C2) capable of measuring the high pressure difference comprises a thick pressure sensitive film (4) and a top electrode plate (5); the shallow groove through-hole (83) and the capacitor (C1) capable of measuring the low pressure difference are arranged correspondingly by means of the thin groove (82); and the shallow groove through-hole (83) and the capacitor (C2) capable of measuring the high pressure difference are arranged correspondingly by means of the second shallow groove (81). By means of the capacitor (C1) capable of measuring the low pressure difference and the capacitor (C2) capable of measuring the high pressure difference, the pressure sensor realizes high-precision measurement in a low pressure section and a high pressure section respectively.

Description

Wide-range high-precision integrated double-film capacitive pressure sensor and manufacturing method thereof

Technical field

[0001] The present invention relates to the field of pressure sensor technology, and particularly relates to a wide-range high-precision integrated dual-membrane capacitive pressure sensor and a manufacturing method thereof, especially in a low-pressure section formed by a thin two-layer pressure sensitive film distributed in a horizontal direction. The high pressure section has the same pressure sensor structure with high measurement sensitivity.

Background technique

[0002] Pressure sensors are widely used in medical, health, industrial process control, automotive electronics, and consumer electronics. There are many types of pressure sensors available on the market. According to the measurement principle, there are several types: strain, silicon piezoresistive, piezoelectric, capacitive, and resonant. Among them, the capacitive pressure sensor is an ideal upgrade product for piezoresistive pressure sensors because of its high sensitivity, fast response, and low temperature influence. The principle is to use the relationship between the capacitance and the effective plate area and the distance between the plates to realize the conversion of the pressure signal to the electrical signal. Traditional capacitive pressure sensor. Because of the characteristics of its structure, the range and sensitivity are mutually constrained. In order to achieve higher sensitivity, it is inevitably at the expense of the range, which limits the application range of such sensors.

technical problem

Problem solution

Technical solution

[0003] In view of the above problems, the present invention provides a wide-range, high-precision integrated dual-film capacitive pressure sensor and a manufacturing method thereof. The measuring structure is mainly composed of two layers of pressure sensitive films having different thicknesses and a fixed two-layer plate. The structure of the left side of the sensor is bottom electrode plate, thin pressure sensitive film, first support material and deformation barrier film from bottom to top, and the right side structure is thick pressure sensitive film, second support material and top electrode plate from bottom to top. . In the left structure, the bottom electrode plate and the thin pressure sensitive film constitute a capacitor C1 for measuring a low voltage difference. In the right structure, the thick pressure sensitive film and the top electrode plate constitute a capacitor C2 for measuring a high voltage difference, when there is a small The pressure difference acts on the sensor, and the thin pressure sensitive film is pressed to produce an upward deformation, which causes the capacitance C1 to become smaller and smaller. The upward pressure deformation of the thick pressure sensitive film is extremely small, resulting in a change in C2 and C1. The ratio is negligible. When the maximum deformation of the thin pressure sensitive film reaches the spacing between the thin pressure sensitive film and the deformation barrier film, the thin pressure sensitive film contacts the deformation barrier film, and the deformation barrier film inhibits further thin pressure sensitive film. Bending upwards to achieve overload protection, the same C1 does not have the ability to measure a larger pressure difference, and this thick pressure sensitive film bends upwards significantly under the action of large differential pressure, causing the capacitance C2 to become larger from small to small, according to the capacitance and the pole. The relationship between the spacing, the variation of the capacitance C2 increases as the pole spacing decreases, ensuring that C2 has a higher sensitivity in the high-voltage range, and the low voltage is realized by the ingenious combination of the two parallel pressure sensitive membranes. High precision measurement of segments and high pressure sections.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A wide-range high-precision integrated dual-film capacitive pressure sensor, comprising a glass substrate, wherein a shallow groove and a shallow groove are provided on the glass substrate, and the shallow groove and the shallow groove are connected through the narrow groove, the shallow groove The two central positions are provided with shallow groove through holes, the shallow groove through holes are extended from the bottom surface of the shallow groove to the bottom surface of the glass substrate, the shallow groove is provided with a capacitor Cl which can measure the low pressure difference, and the shallow groove 2 is provided with the measurable high pressure difference. Capacitor C2, Capacitor C1 that can measure low dropout voltage includes bottom electrode plate and thin pressure sensitive film. Capacitor C2 which can measure high voltage difference includes thick pressure sensitive film and top electrode plate. Shallow groove through hole passes through fine groove and can measure low dropout The capacitor C1 is correspondingly arranged, and the shallow slot through hole is correspondingly set by the shallow slot 2 and the capacitor C2 which can measure the high voltage difference.

[0006] Further, the bottom electrode plate covers the bottom surface of the shallow groove, the left side of the thin pressure sensitive film covers the upper surface of the glass substrate, and the thin pressure sensitive film has a thin pressure sensitive film through hole on the right side of the thin pressure sensitive film. The through hole of the pressure sensitive film is flush with the groove wall of the shallow groove 2. The left side of the thin pressure sensitive film is provided with a deformation blocking film through the first supporting material, and the deformation blocking film through hole is formed on the left side of the deformation blocking film, the deformation blocking film A thick pressure sensitive film is disposed on the right side, and a thick pressure sensitive film covers the first supporting material. The top electrode plate is disposed above the thick pressure sensitive film through the second supporting material, and the top electrode plate is provided with a top electrode plate through hole.

[0007] Further, a first supporting material through hole 1 is disposed on a left side of the first supporting material, and a first supporting material through hole is disposed flush with a groove wall of the shallow groove, and a right side of the first supporting material is disposed There is a first supporting material through hole 2, and the first supporting material through hole 2 is flush with the groove wall of the shallow groove 2.

[0008] Further, the second supporting material is provided with a second supporting material through hole, and the second supporting material through hole is flush with the groove wall of the shallow groove 2. [0009] A wide-range high-precision integrated dual-film capacitive pressure sensor, the manufacturing method thereof, the steps are as follows: [0010] Step one, preparing a cleaned glass substrate, and etching the upper surface with a hydrofluoric acid solution a shallow groove 1 and a shallow groove 2 having a fine groove connection;

[0011] Step two, through the hydrofluoric acid solution etching or laser drilling technology in the shallow groove two center position shallow shallow groove through hole, and the shallow groove through hole from the shallow groove two bottom surface to the bottom surface of the glass substrate;

[0012] Step 3, depositing a layer of aluminum on the bottom surface of the shallow trench by magnetron sputtering as the bottom electrode plate;

[0013] Step 4, preparing the cleaned SOI sheet, the top and bottom layers of the three layers of material are respectively a thin layer of silicon, a silicon dioxide dielectric layer and a bulk silicon layer, and a thin layer of a region is etched by photolithography and dry process. Silicon and silicon dioxide dielectric layer; [0014] Step 5, by anodic bonding technology, the glass substrate and the SOI sheet are aligned and bonded together, the bonding surface is the upper surface of the glass substrate and the thin silicon layer Surface

[0015] Step 6: The body silicon layer of the SOI sheet is thinned to a certain thickness by a chemical mechanical polishing technique, and the thin layer silicon above the shallow trench is used as a thin pressure sensitive film of the sensor, and the bulk silicon above the shallow trench The layer acts as a deformation barrier film of the sensor, and the bulk silicon layer above the shallow groove serves as a thick pressure sensitive film of the sensor;

[0016] Step VII, etching the deformation barrier film via hole at the center of the deformation barrier film by reactive ion etching; [0017] Step VIII, bulk silicon above the shallow trench by chemical vapor deposition and photolithography Depositing a layer of silicon dioxide on the layer;

[0018] Step IX, depositing metal chromium on the deposited silicon dioxide by the magnetron sputtering method, and removing the chromium at the center position by a lift-off technique, and the remaining portion is used as the top electrode plate;

[0019] Step 10, using a hydrofluoric acid solution to etch the silica dielectric layer above the shallow trench, leaving the surrounding portion as the first support material for releasing the thin pressure sensitive film, and etching the shallow trench with the hydrofluoric acid solution The silica, which retains the surrounding portion as a second support material, is used to release the thick pressure sensitive film.

Advantageous effects of the invention

Beneficial effect

[0020] Advantageous effects of the invention:

[0021] 1. The invention adopts the variable pitch principle to realize the pressure-to-capacitance conversion, and the capacitor C1 which can measure the low-drop difference and the capacitor C2 which can measure the high-pressure difference respectively realize the high-precision measurement of the low-pressure section and the high-pressure section, which not only improves the pressure. Measurement accuracy also increases the measurement range of the sensor;

[0022] 2. The deformation barrier film of the invention effectively solves the overload protection of the thin pressure sensitive film under high pressure measurement Problem, the measurement range of the sensor is increased and the reliability is improved;

[0023] 3. The thin pressure sensitive film and the thick pressure sensitive film are all composed of a single material, and the precision is more easily ensured.

Brief description of the drawing

DRAWINGS

1 is a plan view of the overall structure of the present invention;

Figure 2 is a cross-sectional view taken along line A-A of Figure 1;

3 to 12 are flowcharts showing the fabrication of the present invention.

[0027] 1. Bottom electrode plate; 2. Thin pressure sensitive film; 20. Thin pressure sensitive film through hole; 3. Deformation barrier film; 30. Deformation barrier film through hole; 4. Thick pressure sensitive film; 5. Top electrode 50; top electrode plate through hole; 6. first support material; 60. first support material through hole one; 61. first support material through hole two; 7. second support material; 70. second support material Through hole; 8. Glass substrate; 80. Shallow groove one; 81. Shallow groove two; 82. Fine groove; 83. Shallow groove through hole.

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] The technical solution of the present invention will be described below with reference to the accompanying drawings and embodiments.

[0029] As shown in FIG. 1 and FIG. 2, a wide-range high-precision integrated dual-film capacitive pressure sensor according to the present invention comprises a glass substrate 8, and a shallow groove 80 and a shallow groove are provided on the glass substrate 8. 2, 81, shallow groove 80 and shallow groove 2 81 are communicated through the narrow groove 82. The shallow groove 2 is provided with a shallow groove through hole 83 at the center position, and the shallow groove through hole 83 extends from the bottom surface of the shallow groove 2 81 to the bottom surface of the glass substrate 8. The shallow groove 80 is provided with a capacitor C1 capable of measuring a low voltage difference, and the shallow groove 2 81 is provided with a capacitor C2 capable of measuring a high voltage difference, and the capacitor C1 capable of measuring a low voltage difference includes a bottom electrode plate 1 and a thin pressure sensitive film 2, The capacitor C2 for measuring the high voltage difference includes a thick pressure sensitive film 4 and a top electrode plate 5, and the shallow groove through hole 83 is disposed corresponding to the capacitor C1 which can measure the low voltage difference through the narrow groove 82, and the shallow groove through hole 83 passes through the shallow groove two 81 and The capacitance C2 for measuring the high voltage difference is set correspondingly. The above description constitutes the basic structure of the present invention.

[0030] The present invention employs a configuration in which the operation principle is as follows: the pressure acts upwardly on the entire sensor surface (ie, the bottom surface of the glass substrate 8) by the shallow groove through hole 83, and the pressure is at a low pressure (the pressure sensitive film 4 is at a low pressure) The deformation is extremely small, negligible) is transmitted to the shallow groove 80 through the narrow groove 82, causing the thin pressure sensitive film 2 to bend upward, and the measurable low pressure difference capacitance composed of the bottom electrode plate 1 and the thin pressure sensitive film 2 The C1 starts to decrease as the pressure increases. When the pressure reaches a certain value, the thin pressure sensitive film 2 is bent upward to come into contact with the deformation barrier film 3, and the deformation barrier film 3 suppresses further upward bending of the thin pressure sensitive film 2 to prevent thin pressure. Min The sensitized membrane 2 ruptures at a higher pressure, and thereafter, the pressure at the high pressure enthalpy through the shallow groove XX 81 causes the thick pressure sensitive membrane 4 to produce a significant upward deformation at a higher pressure, the thick pressure sensitive membrane 4 and the top electrode The capacitance C2 of the measurable high voltage difference formed by the plate 5 also changes significantly, and the initial increase with the increase of the pressure, and the sensitivity also increases with the increase of the pressure. The invention adopts the variable pitch principle to realize the pressure-to-capacitance conversion, and the capacitor C1 which can measure the low-drop difference and the capacitor C2 which can measure the high-voltage difference respectively realize the high-precision measurement of the low-pressure section and the high-pressure section, thereby improving the pressure measurement accuracy and improving. The measurement range of the sensor. In addition, the deformation barrier film 3 of the present invention effectively solves the overload protection problem of the thin pressure sensitive film 2 under high pressure measurement, and increases the measurement range of the sensor and improves the reliability.

[0031] More specifically, the bottom electrode plate 1 covers the bottom surface of the shallow groove 80, the left side of the thin pressure sensitive film 2 covers the upper surface of the glass substrate 8, and the thin pressure sensitive film 2 is provided with a thin pressure on the right side. The sensitive film through hole 20, the thin pressure sensitive film through hole 20 is flush with the groove wall of the shallow groove two 81, and the left side of the thin pressure sensitive film 2 is provided with a deformation blocking film 3 through the first supporting material 6, and the deformation blocking film 3 is formed. The deformation blocking film through hole 30 is disposed on the left side, the thick pressure sensitive film 4 is disposed on the right side of the deformation blocking film 3, the thick pressure sensitive film 4 is covered on the first supporting material 6, and the top electrode plate 5 is separated by the second supporting material 7. It is disposed above the thick pressure sensitive film 4, and the top electrode plate 5 is provided with a top electrode plate through hole 50. With such a structural arrangement, the present invention utilizes two layers of pressure sensitive membranes and fixed plates of different thicknesses which are laterally parallel distributed to form two capacitive pressure sensors, a shallow groove-80 position bottom electrode plate 1 and a thin pressure sensitive film 2 A capacitor C1 constituting a low-drop difference is formed, and the thick pressure-sensitive film 4 at the position of the shallow groove two 81 and the top electrode plate 5 constitute a capacitor C2 capable of measuring a high-voltage difference.

[0032] More specifically, a first supporting material through hole 60 is disposed on the left side of the first supporting material 6, and the first supporting material through hole 60 is flush with the groove wall of the shallow groove 80, first The first supporting material through hole 216 is disposed on the right side of the supporting material 6, and the first supporting material through hole 216 is flush with the groove wall of the shallow groove XX1. With such a configuration, the thin pressure sensitive film 2 is released through the first support material through hole 60 to facilitate the bending of the thin pressure sensitive film 2 by low pressure.

More specifically, the second supporting material 7 is provided with a second supporting material through hole 70, and the second supporting material through hole 70 is flush with the groove wall of the shallow groove two 81. With such a structural arrangement, the through-holes 70 for releasing the thick pressure sensitive film 4 through the second support material facilitate the high pressure bending of the thick pressure sensitive film 4.

[0034] A wide-range high-precision integrated dual-film capacitive pressure sensor, the manufacturing method thereof, the steps are as follows: [0035] Step one, preparing a cleaned glass substrate 8 and etching the upper surface thereof with a hydrofluoric acid solution With a narrow groove 82 Connected shallow groove 80 and shallow groove 2 81 (as shown in Figure 3);

[0036] Step two, through the hydrofluoric acid solution etching or laser drilling technology in the shallow groove two 81 center position shallow groove through hole

83, and the shallow groove through hole 83 extends from the bottom surface of the shallow groove two 81 to the bottom surface of the glass substrate 8 (as shown in FIG. 4);

[0037] Step 3, depositing a layer of aluminum on the bottom surface of the shallow trench 80 by magnetron sputtering as the bottom electrode plate 1 (as shown in FIG. 5);

[0038] Step 4, preparing the cleaned SOI sheet, the top and bottom of the three layers of material are respectively a thin layer of silicon, a silicon dioxide dielectric layer and a bulk silicon layer, and a thin layer of a region is etched by photolithography and dry process. Silicon and silicon dioxide dielectric layers (as shown in Figure 6);

[0039] Step 5, by anodic bonding technology, the glass substrate 8 and the SOI sheet are aligned and bonded together, the bonding surface is the upper surface of the glass substrate 8 and the upper surface of the thin layer of silicon (as shown in FIG. 7). Show);

[0040] Step 6: by chemical mechanical polishing technology, the bulk silicon layer of the SOI sheet is thinned to a certain thickness, and the thin layer of silicon above the shallow trench 80 is used as the thin pressure sensitive film 2 of the sensor, above the shallow trench 80 The bulk silicon layer acts as the deformation barrier film 3 of the sensor, and the bulk silicon layer above the shallow trench II 81 serves as the thick pressure sensitive film 4 of the sensor (as shown in FIG. 8);

[0041] Step VII, etching the deformation barrier film through hole at the center position of the deformation barrier film 3 by reactive ion etching

(as shown in Figure 9);

[0042] Step VIII, depositing a layer of silicon dioxide on the bulk silicon layer above the shallow trenches 181 by a chemical vapor deposition technique and a photolithography process (as shown in FIG. 10);

[0043] Step IX, depositing metal chromium on the deposited silicon dioxide by the magnetron sputtering method, and removing the chromium at the center position by a lift-off technique, and the remaining portion is used as the top electrode plate 5 (as shown in FIG. 11). Show);

[0044] Step 10: etching the silicon dioxide dielectric layer above the shallow trench 80 with a hydrofluoric acid solution, leaving the surrounding portion as the first support material 6 for releasing the thin pressure sensitive film 2, and etching with a hydrofluoric acid solution. The silicon dioxide above the groove two 81 retains the peripheral portion as the second supporting material 7 for releasing the thick pressure sensitive film 4 (as shown in Fig. 12).

The embodiments of the present invention have been described above with reference to the drawings, but the present invention is not limited to the specific embodiments described above, and the specific embodiments described above are merely illustrative and not restrictive. A person skilled in the art can make various forms within the scope of the present invention without departing from the scope of the invention and the scope of the invention.

Claims

Claim

[Claim 1] A wide-range high-precision integrated dual-film capacitive pressure sensor, comprising: a glass substrate (8) having a shallow groove (80) and a shallow a slot (81), the shallow slot one (80) and the shallow slot two (81) are communicated through the slot (82), and the shallow slot two (81) is provided with a shallow slot through hole (83) at the center position. The shallow slot through hole (83) extends from the bottom surface of the shallow slot 2 (81) to the bottom surface of the glass substrate (8), and the shallow slot one (80) is provided with a capacitor C1 capable of measuring a low voltage difference, the shallow slot 2 ( 81) A capacitor C2 capable of measuring a high voltage difference is provided, and the capacitor C1 capable of measuring a low differential voltage includes a bottom electrode plate (1) and a thin pressure sensitive film (2), wherein the capacitor C2 capable of measuring a high differential voltage includes a thick pressure a sensitive film (4) and a top electrode plate (5), wherein the shallow groove through hole (83) is disposed through a thin groove (82) corresponding to a capacitance C1 capable of measuring a low voltage difference, and the shallow groove through hole (83) is shallow Slot 2 (81) is set corresponding to capacitor C2 which can measure high voltage difference.

[Claim 2] A wide-range, high-precision integrated dual-film capacitive pressure sensor according to claim 1.

The bottom electrode plate (1) covers the bottom surface of the shallow groove (80), and the left side of the thin pressure sensitive film (2) covers the upper surface of the glass substrate (8), the thin pressure A thin pressure sensitive film through hole (20) is disposed on the right side of the sensitive film (2), and the thin pressure sensitive film through hole (20) is flush with the groove wall of the shallow groove two (81), and the thin pressure sensitive film (2) a deformation blocking film (3) is disposed on the left side through the first supporting material (6), and a deformation blocking film through hole (30) is disposed on the left side of the deformation blocking film (3), and the deformation blocking film (30) 3) A thick pressure sensitive membrane (4) is placed on the right side, the thick pressure sensitive membrane (4) is covered on the first support material (6), and the top electrode plate (5) is passed through the second support material (7) The interval is disposed above the thick pressure sensitive film (4), and the top electrode plate (5) is provided with a top electrode plate through hole (50).

[Claim 3] A wide-range high-precision integrated dual-film capacitive pressure sensor according to claim 2

The first support material (6) is provided with a first support material through hole (60) on the left side, and a groove of the first support material through hole (60) and the shallow groove one (80). The wall is flush, the first support material (6) has a first support material through hole 2 (61) on the right side thereof, and the first support material through hole 2 (61) and the shallow groove 2 (81) groove Wall flush setting

[Claim 4] A wide-range, high-precision integrated dual-film capacitive pressure sensor according to claim 2.

The second supporting material (7) is provided with a second supporting material through hole (70), and the second supporting material through hole (70) is flush with the groove wall of the shallow groove two (81). Flat setting

[Claim 5] A wide-range high-precision integrated dual-film capacitive pressure sensor according to any one of claims 1 to 4, wherein the manufacturing method is as follows:

Step one, preparing a cleaned glass substrate (8), and etching a shallow groove (80) and a shallow groove 2 (81) with a fine groove (82) on the upper surface thereof with a hydrofluoric acid solution;

Step 2: through the hydrofluoric acid solution etching or laser drilling technology, the shallow groove through hole (83) is located at the center of the shallow groove 2 (81), and the shallow groove through hole (83) is extended from the bottom surface of the shallow groove 2 (81) to the glass. Substrate (8) bottom surface;

Step 3, depositing a layer of aluminum on the bottom surface of the shallow trench (80) by magnetron sputtering as the bottom electrode plate (1);

Step 4, preparing the cleaned SOI sheet, the top and bottom layers of the three layers of material are respectively a thin layer of silicon, a silicon dioxide dielectric layer and a bulk silicon layer, and a thin layer of silicon and two regions are etched away by photolithography and dry process. Silicon oxide dielectric layer;

Step 5, by anodic bonding technology, the glass substrate (8) and the SOI sheet are aligned and bonded together, and the bonding surface is the upper surface of the glass substrate (8) and the upper surface of the thin silicon layer; Thinning the bulk silicon layer of the SOI sheet to a certain thickness by chemical mechanical polishing

, a thin layer of silicon above the shallow groove (80) as a thin pressure sensitive film for the sensor (2)

The bulk silicon layer above the shallow trench (80) acts as the deformation barrier film of the sensor (3), and the bulk silicon layer above the shallow trench (81) acts as the thick pressure sensitive film of the sensor (4);

Step 7: etching the barrier film through hole (30) at the center of the deformation barrier film (3) by reactive ion etching;

Step 8. depositing a layer of silicon dioxide on the bulk silicon layer above the shallow trench (81) by a chemical vapor deposition technique and a photolithography process;

Step IX, depositing metallic chromium on the deposited silicon dioxide by magnetron sputtering, and The chromium at the center position is removed by a stripping technique, and the remaining portion is used as the top electrode plate (5); Step 10, the silicon dioxide dielectric layer above the shallow groove one (80) is etched with a hydrofluoric acid solution, and the peripheral portion is retained as the first support Material (6) for releasing the thin pressure sensitive film (2), etching the silica above the shallow groove two (81) with a hydrofluoric acid solution, and retaining the surrounding portion as the second supporting material (7) for release Thick pressure sensitive membrane (4).