Micro pressure sensor and packaging manufacturing method

Abstract

The micro-pressure sensor comprises a wafer substrate, a supporting film and a wafer cover plate are sequentially arranged on the wafer substrate from bottom to top, an etching cavity is formed in the center of the lower surface of the wafer cover plate, and a cross-shaped pressing column is arranged in the middle of the etching cavity; the lower surface of the cross pressing column tightly abuts against the middle of the upper surface of the supporting film, a piezoelectric material film is embedded in the middle of the lower surface of the supporting film, an interdigital electrode is attached to the lower surface of the piezoelectric material film, an induction cavity is formed in the middle of the upper surface of the wafer substrate, and TSV conductive columns are arranged in the wafer substrate and located on the two sides of the induction cavity in a penetrating mode respectively. The upper ends of the TSV conductive columns are correspondingly and electrically connected with the positive electrode and the negative electrode of the interdigital electrode respectively, the lower ends of the TSV conductive columns are electrically connected with metal solder balls, a transmission part and an acoustic resonance part can be isolated, the manufacturing process is equivalent to the fact that the acoustic resonance part adopts an inverted structure, and the sensor is long in service life and can be suitable for various severe environments.

Description

Technical Field

[0001] The invention relates to the technical field of sensors, in particular to a micro pressure sensor and a packaging manufacturing method. Background Art

[0002] Pressure sensors are one of the most widely used sensors and are widely used in various industrial automatic control environments, involving many industries such as water conservancy and hydropower, railway transportation, intelligent buildings, production automatic control, aerospace, military industry, petrochemicals, oil wells, electricity, ships, machine tools, pipelines, etc.

[0003] The application document with publication number CN113790833A discloses a pressure sensor, including a substrate layer and a piezoelectric stack structure arranged on the upper surface of the substrate layer, a groove is arranged on the upper surface of the substrate layer, and a closed first cavity is formed between the groove and the piezoelectric stack structure. A closed second cavity is also formed inside the substrate layer, and the second cavity is separated from the first cavity and is located under the first cavity.

[0004] The above-mentioned device has the following shortcomings: the above-mentioned device lacks a protective structure for the acoustic resonator structure itself when in use, resulting in a short service life and a single application scenario. In addition, the above-mentioned device needs to maintain a vacuum environment during production, the production process is difficult, and additional packaging processes are still required, and the overall production cost is high. Summary of the invention

[0005] The purpose of the present invention is to provide a micro pressure sensor and a packaging manufacturing method to improve the overall work efficiency in view of the above-mentioned problems and shortcomings.

[0006] The present invention solves at least one of the following technical problems:

[0007] (1) The above device lacks a protective structure for the acoustic resonator structure itself during use, resulting in a short service life and a single application scenario;

[0008] (2) The above-mentioned device needs to maintain a vacuum environment during production, the production process is difficult, and additional packaging processes are still required, resulting in a high overall production cost.

[0009] The objective of the present invention can be achieved through the following technical scheme: a micro pressure sensor, comprising a wafer substrate, on which a supporting film and a wafer cover are arranged in sequence from bottom to top, an etched cavity is opened in the center of the lower surface of the wafer cover, a cross pressure column is arranged in the middle of the etched cavity, the lower surface of the cross pressure column is tightly abutted against the middle of the upper surface of the supporting film, a piezoelectric material film is embedded in the middle of the lower surface of the supporting film, a forked electrode is attached to the lower surface of the piezoelectric material film, an induction cavity is opened in the middle of the upper surface of the wafer substrate, TSV conductive columns are respectively penetrated in the wafer substrate and located on both sides of the induction cavity, the upper ends of the TSV conductive columns are respectively electrically connected to the positive and negative electrodes of the forked electrodes, and the lower ends of the TSV conductive columns are electrically connected to metal solder balls.

[0010] A packaging and manufacturing method for a micro pressure sensor, the method comprising the following steps:

[0011] S1: Make substrate, provide wafer substrate, and open sensing cavity;

[0012] S2: making a resonant mechanism, filling a sacrificial filler into the sensing cavity, then sequentially forming an interdigitated electrode and a piezoelectric material film on the upper surface of the sacrificial filler, and then forming a supporting film, and making the supporting film cover the upper surface of the wafer substrate and the upper surface of the piezoelectric material film;

[0013] S3: manufacturing a cover plate, providing a wafer cover plate, opening an etching cavity in the middle of the lower surface of the wafer cover plate, and forming a cross pressure column in the etching cavity;

[0014] S4: bonding, aligning and bonding the wafer cover plate and the wafer substrate together, and aligning and closely contacting the cross pressure pin with the middle of the upper surface of the supporting film;

[0015] S5: processing the substrate, burying TSV conductive pillars in the wafer substrate, wherein the upper ends of the two TSV conductive pillars are electrically connected to the positive and negative electrodes of the interdigital electrodes respectively, and then the sacrificial filler in the sensing cavity is emptied, and then a metal solder ball is welded to the lower end of the TSV conductive pillar;

[0016] S6: Test the sensor. Connect the sensor to the test circuit, apply different pressures on the upper surface of the wafer cover, calculate the corresponding value based on the different electrical signals measured, and then compare it with the applied pressure to detect the quality of the sensor and complete the manufacturing and packaging.

[0017] As a further solution of the invention, in step S1, an etching process, such as a photolithography process, is used to etch the middle portion of the upper surface of the wafer substrate to form a sensing cavity, and the top edge of the sensing cavity is wrapped around the piezoelectric material film.

[0018] As a further solution of the invention, in step S2, a sacrificial filler is filled into the sensing cavity using a sacrificial layer filling process, and then a CMP planarization process is used to make the upper surface of the sacrificial filler flush with the upper surface of the wafer substrate. The material of the sacrificial filler can be PSG or TEOS.

[0019] As a further solution of the invention, in step S2, when making the interdigitated electrodes, the electrode metal is deposited on the upper surface of the sacrificial filler using a deposition process, such as a PVD process, and then the deposited electrode metal is trimmed into a centrally symmetrical comb-like structure using an etching process, such as a photolithography process, to form the interdigitated electrodes.

[0020] As a further solution of the invention, in step S2, when making the piezoelectric material film, the piezoelectric material is deposited on the interdigital electrodes using a deposition process, such as a PVD process. The piezoelectric material can be one or more of PZT, AlN or thin film lithium niobate.

[0021] As a further solution of the invention, in step S, when making the support film, a deposition process, such as LPCVD process, is used to deposit silicon material on top of the piezoelectric material film. The silicon material can be polycrystalline silicon, and the thickness of the support film ranges from 0.5um to 5um.

[0022] As a further solution of the invention, in step S3, an etching process, such as a photolithography process, is used, and the four sides of the etched cavity are made larger than the sensing cavity. When etching and forming a cross pressure column, side pressure columns are formed at the angles between each adjacent side of the cross pressure column.

[0023] As a further solution of the invention, in step S5, an etching process, such as a photolithography process, is used to open a first channel on the wafer substrate at positions corresponding to the positive and negative poles of the interdigitated electrodes, and a second channel is opened on the wafer substrate at the bottom of the sensing cavity. The cross-sectional diameter of the first channel matches the electrode width of the interdigitated electrodes, and the cross-sectional diameter of the second channel is much smaller than the first channel.

[0024] As a further solution of the invention, in step S5, the sacrificial filler is completely released from the second channel through a release process, such as a wet release process or a gaseous hydrogen fluoride release process, so that the sensing cavity forms a complete cavity structure. In step S5, TSV conductive columns are formed in the first channel through ALD deposition and electroplating processes, and the TSV conductive columns are electrically connected to the positive and negative electrodes of the interdigitated electrodes respectively.

[0025] Beneficial effects of the present invention:

[0026] (1) The present invention can directly manufacture and package wafer-level pressure sensors, and can isolate transmission components and acoustic resonant components. The manufacturing process is equivalent to using a flip-chip structure for the acoustic resonant component. Due to the flip-chip acoustic resonator process structure and steps, the present invention has the advantages of isolating the transmission column and the resonator, and having a longer working life of the sensor. At the same time, the use environment of the sensor is almost unrestricted and can be applied to various harsh environments.

[0027] (2) The stable electrical connection formed by the TSV process after bonding of the present invention makes the generation and transmission process of the electrical signal of the present invention very stable, so that the pressure can be accurately sensed and the value can be accurately output to the outside, thereby improving the overall working accuracy;

[0028] (3) The present invention utilizes two wafers and a polysilicon film to form a device package by silicon-silicon bonding, thereby achieving more efficient durability and high temperature resistance, and can reduce the steps of the subsequent slicing process, saving the overall manufacturing cost;

[0029] (4) The present invention calculates the frequency shift by using the deformation of the support column on the surface of the resonant component caused by the change in pressure, thereby calculating the pressure. The resonant component can be made extremely thin, thereby achieving better working accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0031] Figure 1 It is the overall structural front view of the present invention;

[0032] Figure 2 It is a side view of the planar structure of the present invention;

[0033] Figure 3 for Figure 2 Sectional view of the middle section AA;

[0034] Figure 4 A bottom view of the overall structure of the wafer cover plate of the present invention;

[0035] Figures 5 to 17 It is a schematic diagram of the manufacturing process of the present invention;

[0036] In the figure: 101, wafer substrate; 102, sensing cavity; 103, sacrificial filler; 104, interdigital electrode; 105, piezoelectric material film; 106, supporting film; 107, first channel; 108, second channel; 109, TSV conductive column; 110, metal solder ball; 201, wafer cover; 202, etched cavity; 203, cross pressure column; 204, side pressure column. DETAILED DESCRIPTION

[0037] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation mode, structure, characteristics and effects of the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0038] See also Figure 1-17 As shown: a micro pressure sensor, including a wafer substrate 101, on which a supporting film 106 and a wafer cover plate 201 are arranged in order from bottom to top, an etched cavity 202 is opened at the center of the lower surface of the wafer cover plate 201, a cross pressure column 203 is arranged in the middle of the etched cavity 202, the lower surface of the cross pressure column 203 is tightly abutted with the middle of the upper surface of the supporting film 106, a piezoelectric material film 105 is embedded in the middle of the lower surface of the supporting film 106, and a forked electrode 104 is attached to the lower surface of the piezoelectric material film 105, a sensing cavity 102 is opened in the middle of the upper surface of the wafer substrate 101, TSV conductive columns 109 are respectively penetrated in the wafer substrate 101 and located on both sides of the sensing cavity 102, the upper ends of the TSV conductive columns 109 are respectively electrically connected to the positive and negative electrodes of the forked electrode 104, and the lower ends of the TSV conductive columns 109 are electrically connected to the metal solder balls 110;

[0039] When this embodiment is working, the sensor of this embodiment is attached to the surface of the to-be-tested position of the object to be tested, for example, attached to a certain surface of the PCB substrate. When sensing pressure, the middle part of the surface of the wafer cover plate 201 is subjected to force, and the cross pressure column 203 is subjected to pressure to produce an up and down displacement, which excites the supporting film 106 and the piezoelectric material film 105 thereon and the interdigital electrode 104 to produce tensile or compressive deformation, thereby generating an electrical signal corresponding to the pressure. The electrical signal is then analyzed to calculate the pressure of the environment in which the sensor and the object to which it is attached are located.

[0040] Specifically, the packaging and manufacturing method of the micro pressure sensor comprises the following steps:

[0041] S1: manufacturing a substrate, providing a wafer substrate 101, and opening a sensing cavity 102;

[0042] S2: manufacturing a resonant mechanism, filling the sensing cavity 102 with a sacrificial filler 103, then sequentially forming an interdigitated electrode 104 and a piezoelectric material film 105 on the upper surface of the sacrificial filler 103, and then forming a supporting film 106, and making the supporting film 106 cover the upper surface of the wafer substrate 101 and the upper surface of the piezoelectric material film 105;

[0043] S3: manufacturing a cover plate, providing a wafer cover plate 201, opening an etching cavity 202 in the middle of the lower surface of the wafer cover plate 201, and forming a cross pressure column 203 in the etching cavity 202;

[0044] S4: bonding, aligning and bonding the wafer cover plate 201 and the wafer substrate 101 together, and aligning and closely contacting the cross pressure pin 203 with the middle of the upper surface of the supporting film 106;

[0045] S5: processing the substrate, embedding TSV conductive pillars 109 in the wafer substrate 101, wherein the upper ends of the two TSV conductive pillars 109 are electrically connected to the positive and negative electrodes of the interdigital electrodes 104 respectively, and then the sacrificial filler 103 in the sensing cavity 102 is emptied, and then the metal solder ball 110 is welded to the lower end of the TSV conductive pillars 109;

[0046] S6: Test the sensor, connect the sensor to the test circuit, apply different pressures on the upper surface of the wafer cover 201, calculate the corresponding values ​​based on the different measured electrical signals, and then compare them with the applied pressure to detect the quality of the sensor and complete the manufacturing and packaging.

[0047] In step S1 , an etching process, such as a photolithography process, is used to etch the middle portion of the upper surface of the wafer substrate 101 to form a sensing cavity 102 , and the top edge of the sensing cavity 102 is in an envelope form around the piezoelectric material film 105 .

[0048] In step S2, a sacrificial filler 103 is filled into the sensing cavity 102 using a sacrificial layer filling process, and then a CMP planarization process is used to make the upper surface of the sacrificial filler 103 flush with the upper surface of the wafer substrate 101. The material of the sacrificial filler 103 can be PSG (phosphosilicate glass) or TEOS (tetraethyl orthosilicate).

[0049] In step S2, when manufacturing the interdigital electrodes 104, electrode metal is deposited on the upper surface of the sacrificial filler 103 by using a deposition process, such as a PVD process, and then the deposited electrode metal is trimmed into a centrally symmetrical comb-shaped structure by using an etching process, such as a photolithography process, to form the interdigital electrodes 104;

[0050] The interdigital spacing of the interdigital electrodes 104 is adjusted according to the designed frequency, ranging from 1 um to 100 nm;

[0051] The material of the interdigital electrodes 104 may be one or more of Mo, Al, Au or Pt.

[0052] In step S2, when manufacturing the piezoelectric material film 105, a deposition process, such as a PVD process, is used to deposit the piezoelectric material on the interdigital electrodes 104. The piezoelectric material may be one or more of PZT, AlN or thin-film lithium niobate.

[0053] In step S2, when manufacturing the support film 106, a deposition process, such as LPCVD process, is used to deposit silicon material on the piezoelectric material film 105. The silicon material may be polycrystalline silicon. The thickness of the support film 106 is in the range of 0.5um-5um.

[0054] In step S3, an etching process, such as a photolithography process, is used to make the four sides of the etched cavity 202 larger than the sensing cavity 102;

[0055] When the cross pressure pillar 203 is etched and formed, side pressure pillars 204 are formed at the angles between adjacent sides of the cross pressure pillar 203 .

[0056] In step S4, the bonding method may be silicon-silicon bonding, and the two wafers are aligned and then bonded into one.

[0057] In step S5, an etching process, such as a photolithography process, is used to open a first channel 107 on the wafer substrate 101 at positions corresponding to the positive and negative electrodes of the interdigitated electrodes 104, and a second channel 108 is opened on the wafer substrate 101 at the bottom of the sensing cavity 102. The cross-sectional diameter of the first channel 107 matches the electrode width of the interdigitated electrodes 104, and the cross-sectional diameter of the second channel 108 is much smaller than that of the first channel 107.

[0058] In step S5 , the sacrificial filler 103 is completely released from the second channel 108 through a release process, such as a wet release process or a gaseous hydrogen fluoride release process, so that the sensing cavity 102 forms a complete cavity structure.

[0059] In step S5 , a TSV conductive pillar 109 is formed in the first channel 107 by ALD deposition and electroplating processes, and the TSV conductive pillar 109 is electrically connected to the positive and negative electrodes of the interdigital electrodes 104 respectively.

[0060] In step S6, the test steps are as follows: the electrical signal value obtained when the applied pressure is zero is recorded as F0, and then the electrical signal value obtained when the force is applied in a direction perpendicular to the interdigital electrode 104 is recorded as F1, and the electrical signal value obtained when the force is applied in a direction perpendicular to the interdigital electrode 104 is recorded as F2. After comparing F1 and F2 with F0, the numerical value of the applied pressure is calculated.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A micro pressure sensor, characterized in that: The invention comprises a wafer substrate (101), on which a supporting film (106) and a wafer cover plate (201) are sequentially arranged from bottom to top, an etching cavity (202) is opened at the center of the lower surface of the wafer cover plate (201), a cross pressure column (203) is arranged in the middle of the etching cavity (202), the lower surface of the cross pressure column (203) is tightly abutted against the middle of the upper surface of the supporting film (106), a piezoelectric material film (105) is embedded in the middle of the lower surface of the supporting film (106), and a pressure An interdigital electrode (104) is attached to the lower surface of the electrical material film (105); a sensing cavity (102) is opened in the middle of the upper surface of the wafer substrate (101); TSV conductive columns (109) are respectively provided in the wafer substrate (101) and on both sides of the sensing cavity (102); the upper ends of the TSV conductive columns (109) are respectively electrically connected to the positive and negative electrodes of the interdigital electrode (104); and the lower ends of the TSV conductive columns (109) are electrically connected to metal solder balls (110).

2. A packaging and manufacturing method for a micro pressure sensor, characterized in that: The method comprises the following steps: S1: manufacturing a substrate, providing a wafer substrate (101), and opening a sensing cavity (102); S2: manufacturing a resonant mechanism, filling a sacrificial filler (103) into the sensing cavity (102), then sequentially forming an interdigitated electrode (104) and a piezoelectric material film (105) on the upper surface of the sacrificial filler (103), and then forming a supporting film (106), and making the supporting film (106) cover the upper surface of the wafer substrate (101) and the upper surface of the piezoelectric material film (105); S3: manufacturing a cover plate, providing a wafer cover plate (201), opening an etching cavity (202) in the middle of the lower surface of the wafer cover plate (201), and forming a cross pressure column (203) in the etching cavity (202); S4: bonding, aligning and bonding the wafer cover plate (201) and the wafer substrate (101) together, and aligning and tightly contacting the cross pressure column (203) with the middle of the upper surface of the supporting film (106); S5: processing the substrate, embedding TSV conductive pillars (109) in the wafer substrate (101), wherein the upper ends of the two TSV conductive pillars (109) are respectively and electrically connected to the positive electrode and the negative electrode of the interdigital electrode (104), and then the sacrificial filler (103) in the sensing cavity (102) is emptied, and then a metal solder ball (110) is welded to the lower end of the TSV conductive pillar (109); S6: Testing the sensor, connecting the sensor to a test circuit, applying different pressures on the upper surface of the wafer cover plate (201), calculating corresponding values ​​based on the different electrical signals measured, and then comparing them with the applied pressures to detect the quality of the sensor, and completing the manufacturing and packaging.

3. The packaging and manufacturing method of a micro pressure sensor according to claim 2, characterized in that: In step S1, an etching process, such as a photolithography process, is used to etch the middle portion of the upper surface of the wafer substrate (101) to form a sensing cavity (102), and the top edge of the sensing cavity (102) is wrapped around the piezoelectric material film (105).

4. The packaging and manufacturing method of a micro pressure sensor according to claim 2, characterized in that: In step S2, a sacrificial filler (103) is filled into the sensing cavity (102) using a sacrificial layer filling process, and then a CMP planarization process is used to make the upper surface of the sacrificial filler (103) flush with the upper surface of the wafer substrate (101). The material of the sacrificial filler (103) can be PSG or TEOS.

5. The packaging and manufacturing method of a micro pressure sensor according to claim 2, characterized in that: In step S2, when manufacturing the interdigitated electrode (104), a deposition process, such as a PVD process, is used to deposit electrode metal on the upper surface of the sacrificial filler (103), and then an etching process, such as a photolithography process, is used to trim the deposited electrode metal into a centrally symmetrical comb-like structure to form the interdigitated electrode (104).

6. The packaging and manufacturing method of a micro pressure sensor according to claim 2, characterized in that: In step S2, when manufacturing the piezoelectric material film (105), a deposition process, such as a PVD process, is used to deposit the piezoelectric material on the interdigital electrodes (104). The piezoelectric material may be one or more of PZT, AlN or thin film lithium niobate.

7. The packaging and manufacturing method of a micro pressure sensor according to claim 2, characterized in that: In step S2, when manufacturing the support film (106), a deposition process, such as LPCVD process, is used to deposit silicon material on the piezoelectric material film (105). The silicon material can be polycrystalline silicon. The thickness of the support film 106 ranges from 0.5um to 5um.

8. The packaging and manufacturing method of a micro pressure sensor according to claim 2, characterized in that: In step S3, an etching process, such as a photolithography process, is used to make the four sides of the etched cavity (202) larger than the sensing cavity (102). When a cross pressure column (203) is etched and formed, a side pressure column (204) is formed at the angle between each adjacent side of the cross pressure column (203).

9. The packaging and manufacturing method of a micro pressure sensor according to claim 2, characterized in that: In step S5, an etching process, such as a photolithography process, is used to open a first channel (107) on the wafer substrate (101) at positions corresponding to the positive and negative electrodes of the interdigitated electrodes (104), and a second channel (108) is opened on the wafer substrate (101) at the bottom of the sensing cavity (102). The cross-sectional diameter of the first channel (107) matches the electrode width of the interdigitated electrodes (104), and the cross-sectional diameter of the second channel (108) is much smaller than that of the first channel (107).

10. The packaging and manufacturing method of a micro pressure sensor according to claim 9, characterized in that: In step S5, the sacrificial filler (103) is completely released from the second channel (108) through a release process, such as a wet release process or a gaseous hydrogen fluoride release process, so that the sensing cavity (102) forms a complete cavity structure. In step S5, a TSV conductive column (109) is formed in the first channel (107) through an ALD deposition and electroplating process, and the TSV conductive column (109) is electrically connected to the positive and negative electrodes of the interdigital electrodes (104) respectively.

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