Gauge pressure sensor with isolation structure and preparation method and packaging structure thereof
By designing an isolation structure in the gauge pressure sensor, absorbing and releasing external environmental changes and packaging stress, the problems of high cost, large volume and poor performance stability of traditional gauge pressure sensors are solved, and the effects of miniaturization, low cost and high precision are achieved.
Patent Information
- Application Number
- CN202411837567.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-13
- Publication Date
- 2025-03-21
AI Technical Summary
Traditional gauge pressure sensors have high cost, large size and poor performance stability, making them difficult to meet the needs of miniaturization, low cost and high precision applications.
A gauge pressure sensor with an isolation structure is designed, including a chip outer frame, an isolation structure and an inner chip structure. The isolation structure is formed by an etching process and surrounds the inner chip structure and the outer frame of the chip, absorbing and releasing the changes in the external environment and stresses generated during the packaging process.
It improves the stability and accuracy of the sensor, reduces zero-point output, enhances anti-environmental interference capabilities, and achieves the goal of small size and low cost.
Smart Images
Figure CN119660667A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of microelectronic sensors and relates to a gauge pressure sensor with an isolation structure and a preparation method and a packaging structure thereof. Background Art
[0002] In recent years, with the widespread use of consumer electronic products, MEMS sensors have gradually developed towards miniaturization and low cost. However, most traditional gauge pressure sensors use ceramic or metal packaging, which is costly, large in size, and poor in performance stability, and cannot meet the needs of the application market. Therefore, it is urgent to produce a gauge pressure sensor with good stability, high accuracy, small zero output, strong anti-environmental interference ability, small size, and low cost. Summary of the invention
[0003] The gauge pressure sensor with an isolation structure and the packaging structure thereof of the present invention not only solve the influence of stress generated in the packaging process on the performance, but also improve the ability to resist environmental interference in the application process.
[0004] The object of the present invention is to provide a gauge pressure sensor with an isolation structure, comprising a chip outer frame, an isolation structure and an inner chip structure.
[0005] The chip outer frame is located at the outermost side of the gauge pressure sensor and is used for supporting and fixing the entire structure and connecting it with the outside world, including the electrode lead-out terminal and the substrate structure.
[0006] The isolation structure is connected to the chip frame at one end and to the inner chip structure at the other end, that is, it surrounds the outer side of the inner chip structure and the inner side of the chip frame, and includes an isolation suspension beam and a narrow slit. The isolation suspension beam can be a folded beam or a straight beam, and the number of beams is ≥1. It is made by etching process. The number, length and form of the isolation suspension beam can be designed according to the actual manufacturing process of the sensor or the stress caused by the application occasion so that the sensor has the effect of stress isolation. The narrow slit is a multi-fold form, distributed on the outer side of the inner chip structure and the inner side of the chip frame, and the number of folds of the narrow slit is ≥1.
[0007] The inner chip structure is located inside the gauge pressure sensor structure and is connected to the chip outer frame by an isolation structure. It includes a thin film structure, a piezoresistive resistor and a cavity structure, and is mainly used to detect pressure signals and convert them into electrical signals for output.
[0008] At the same time, the present invention also provides a packaging form of a gauge pressure sensor with an isolation structure, including a gauge pressure sensor with an isolation structure, an adhesive, a frame, an atmospheric vent, a plastic packaging material and a lead.
[0009] The lower surface of the cavity structure in the inner chip structure is connected to the frame, and the upper surface is connected to the lower surface of the film structure in the inner chip structure. The plastic packaging material is connected to the chip outer frame of the gauge pressure sensor on all sides, and its bottom surface is connected to the frame to protect the gauge pressure sensor with an isolation structure inside.
[0010] The lead wire is used to connect the electrical signal of the gauge pressure sensor with an external signal and is protected and fixed by a plastic packaging material, so that the lead wire can resist the impact of the external environment and improve the overload resistance of the gauge pressure sensor with an isolation structure.
[0011] The atmospheric vent is located on the frame and connected to the lower surface of the cavity structure, and is used to connect the lower surface of the thin film structure of the inner chip structure in the gauge pressure sensor to the outside atmosphere. The upper surface of the thin film structure is connected to the ambient pressure to form a gauge pressure sensor structure for pressure testing. The lead is located in the plastic packaging material and is used to connect the electrical signal of the gauge pressure sensor to the external signal. The adhesive is located on the frame and connected to the area of the lower surface of the cavity structure of the inner chip structure except the atmospheric vent.
[0012] The frame is located below the entire packaging structure and plays a role in supporting and electrically connecting the entire structure.
[0013] The chip outer frame of the gauge pressure sensor with an isolation structure is connected to the plastic packaging material on all sides, and the bottom surface is connected to the frame through adhesive. The inner chip structure is separated from the plastic packaging material by the isolation structure, so that the gauge pressure sensor is not affected by the packaging process and changes in the external environment.
[0014] Compared with the existing structure, the gauge pressure sensor with an isolation structure of the present invention has the following advantages:
[0015] First, good stability and high precision. The isolation structure of the gauge pressure sensor proposed by the present invention can eliminate the influence of changes in the external environment on the performance of the internal chip structure itself during the application process, so it has good stability and high precision.
[0016] Second, the zero-point output is small. The gauge pressure sensor with an isolation structure proposed by the present invention can absorb the stress generated during the packaging process, so that the film structure in the chip structure is deformed less, and thus the zero-point output is small.
[0017] Third, it has strong anti-environmental interference capability. The lead wire of the gauge pressure sensor with an isolation structure proposed by the present invention is wrapped by a plastic packaging material, the lead wire is firm and not easy to break, and the signal transmission can be maintained in a complex environment, so it has strong anti-environmental interference capability.
[0018] Fourth, small size and low cost. The gauge pressure sensor with an isolation structure proposed by the present invention is packaged with plastic packaging materials. Compared with traditional packaging forms, it has small size, cheap materials and low cost.
[0019] Another object of the present invention is to provide a method for preparing the gauge pressure sensor with an isolation structure, which method has a simple process and comprises the following steps:
[0020] 1. SOI silicon wafer front oxidation, photolithography, and implantation to form piezoresistive resistors;
[0021] 2. Photolithography and etching on the front side of SOI silicon wafer to form electrode lead holes;
[0022] 3. Metal is sputtered on the front of the SOI silicon wafer, and the metal is photoetched and etched to form leads and pads;
[0023] 4. A passivation layer is deposited on the front of the SOI silicon wafer, and the electrode lead interface is formed by photolithography and etching;
[0024] 5. The front side of the SOI silicon wafer is photolithographically processed and etched to the oxide layer, and beams and narrow slits are formed on the front side;
[0025] 6. Photolithography and etching of the back side of the SOI silicon wafer until it is penetrated to form isolation cantilever beams, narrow gaps, inner chips and cavity structures;
[0026] 7. Slicing;
[0027] Advantages and positive effects of the present invention:
[0028] The gauge pressure sensor with an isolation structure of the present invention has an isolation structure designed on the outer surface of the inner chip structure, which can absorb changes in the external environment and stress generated during the packaging process, thereby preventing the inner chip structure from being affected by the external environment and having stable and reliable performance. The packaging form of the gauge pressure sensor with an isolation structure is also described, in which the lower surface of the thin film structure in the inner chip structure of the gauge pressure sensor is connected to the external atmosphere by designing an atmospheric vent on the frame, and the upper and lower surfaces of the thin film structure are separated by connecting the lower surface of the gauge pressure sensor to the frame with an adhesive, so as to form a gauge pressure sensor for pressure detection.
[0029] Compared with traditional gauge pressure sensors, the gauge pressure sensor with an isolation structure of the present invention not only solves the influence of the stress generated in the packaging process on the performance of the gauge pressure sensor itself, but also improves the ability of the gauge pressure sensor to resist environmental interference during application. It has a simple manufacturing process and has the characteristics of good stability, high precision, small zero point output, strong resistance to environmental interference, small size, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG1 is a schematic diagram of the sensor structure with an isolation structure of the present invention. FIG1(a) is a top view of a sensor with a folded beam isolation structure, FIG1(b) is a top view of a sensor with a straight beam isolation structure, and FIG1(c) is a cross-sectional view of the central axis of a gauge pressure sensor with an isolation structure.
[0031] Figure 2 Schematic diagram of the gauge pressure sensor package with an isolation structure.
[0032] Figure 3(a) to Figure 3(f) The present invention mainly provides a preparation process for the gauge pressure sensor with an isolation structure.
[0033] In the figure:
[0034] 1-substrate structure 2-film structure 3-piezoresistive resistor 4-electrode lead 5-isolation cantilever 6-narrow slit 7-cavity structure
[0035] 8-isolation structure 9-internal chip structure 10-chip frame 11-gauge pressure sensor with isolation structure 12-adhesive
[0036] 13-frame 14-atmospheric vent 15-plastic sealing material 16-lead 17-gauge pressure sensor packaging structure with isolation structure DETAILED DESCRIPTION
[0037] Example 1: Sensor structure with isolation structure
[0038] Figures 1(a) and (b) show a top view of a sensor with an isolation structure. This structure adopts the form of surrounding the isolation structure 8 outside the inner chip structure 9 and connecting it to the chip outer frame 10 to prevent the packaging process or external environmental factors from interfering with the performance of the internal chip 9. The isolation structure 8 includes an isolation suspension beam 5 and a narrow slit 6. The isolation suspension beam 5 can be in the form of a folded beam or a straight beam. The number of beams is ≥1. The number of isolation suspension beams drawn in this example is 4, and they are centrally symmetrically distributed with the center of the inner chip structure 9. The stress changes caused by changes in the chip outer frame 10 due to changes in external environmental factors are released through the isolation structure 8, and the inner chip structure 9 completely overlaps with the center of the chip outer frame 10, that is, the upper, lower, left, and right directions of the inner chip structure 9 have the same strength of resisting external interference, so that the inner chip structure 9 is isolated from the external environment. The longer the length of the isolation suspension beam, the better the stress release effect caused by changes in the external environment. Therefore, the number and length of the isolation suspension beam can be designed according to the stress caused by the actual manufacturing process or application of the sensor to achieve the effect of stress isolation.
[0039] Example 2: Gauge pressure sensor structure with isolation structure
[0040] FIG1(c) shows a cross-sectional view of the central axis of a gauge pressure sensor with the isolation structure of FIG1(a) and (b). The gauge pressure sensor 11 with an isolation structure of the present invention is composed of an isolation structure 8, an inner chip structure 9 and a chip outer frame 10. The isolation structure 8 is composed of an isolation cantilever 5 and a narrow slit 6, which is located between the inner chip structure 9 and the chip outer frame 10. They are formed by an SOI silicon wafer through an etching process, and their main function is to release the stress of the chip outer frame 10 caused by changes in the external environment; the inner chip structure 9 is composed of a thin film structure 2, a piezoresistive resistor 3 and a cavity structure 7, and is located at the center of the gauge pressure sensor structure, and its main function is to convert the external pressure signal into an electrical signal for output; the chip outer frame 10 is composed of an electrode lead-out terminal 4 and a substrate structure 1, and is located on the outside of the gauge pressure sensor structure, playing a role in supporting the entire structure and connecting it to the outside world.
[0041] Example 3: Packaging of a gauge pressure sensor structure with an isolation structure
[0042] The packaging structure of FIG1(c) with the isolation structure of FIG1(a) and (b) is as follows Figure 2 As shown. The gauge pressure sensor packaging structure 17 with an isolation structure of the present invention is composed of a gauge pressure sensor 11 with an isolation structure, an adhesive 12, a frame 13, an atmospheric vent 14, a plastic packaging material 15 and a lead 16. The gauge pressure sensor 11 is connected to the frame 13 through the adhesive 12; the vent 14 is located on the frame 13, and is connected to the cavity structure 7 of the inner chip structure 9 in the gauge pressure sensor 11. The lower surface of the inner chip structure 9 seals the lower surface of the cavity structure 7 through the adhesive 12, so that the lower surface of the film structure 2 is connected to the external atmospheric pressure only through the atmospheric vent 14, and the upper surface of the film structure 2 is connected to the ambient pressure, thereby forming a gauge pressure sensor structure for pressure testing. The plastic encapsulation material 15 completely surrounds the chip outer frame 10 in the gauge pressure sensor 11 with an isolation structure, and is separated from the inner chip structure 9 in the gauge pressure sensor 11 by the isolation structure 8. Therefore, the residual stress of the gauge pressure sensor with an isolation structure of the present invention will be released through the isolation structure 8 during the packaging process, and the interference of the external environment on the gauge pressure sensor of the present invention in the subsequent application process will also be eliminated through the isolation structure 8, so that the performance of the gauge pressure sensor 11 with an isolation structure is stable and reliable. The lead 16 is wrapped in the plastic encapsulation material 15, making the lead 16 more firm and durable, and improving the overload resistance of the gauge pressure sensor 11 with an isolation structure.
[0043] Example 4: Preparation method of a gauge pressure sensor with an isolation structure
[0044] The main preparation process of gauge pressure sensor with isolation structure.
[0045] 1. The SOI silicon wafer is oxidized, photolithographically processed, and implanted to form a piezoresistive resistor, as shown in Figure 3(a);
[0046] 2. Boron push on SOI silicon wafer, deposit silicon dioxide on the front, photolithography and etching to form electrode lead holes, as shown in Figure 3(b);
[0047] 3. Metal is sputtered on the front of the SOI silicon wafer, and the metal is photolithographically and etched to form leads and pads to transmit and convert electrical signals, as shown in Figure 3(c);
[0048] 4. A passivation layer is deposited on the front of the SOI silicon wafer, and an electrode lead interface is formed by photolithography and etching, as shown in FIG3(d);
[0049] 5. The front side of the SOI silicon wafer is photolithographically processed and etched to the oxide layer, and beams and narrow slits are formed on the front side, as shown in FIG3(e);
[0050] 6. The back of the SOI silicon wafer is photolithographically processed and etched until it is penetrated to form an isolation cantilever, a narrow gap, an inner chip and a cavity structure, as shown in Figure 3
[0051] (f)
[0052] 7. Slicing.
[0053] The above method is used to prepare a gauge pressure sensor with an isolation structure. The structure is divided into three parts from the outside to the inside, namely, a chip frame, an isolation structure and an inner chip structure. The three structures are formed by an etching process, and the isolation structure connects the chip frame and the inner chip structure into a whole. The chip frame is mainly used to support, fix and connect the gauge pressure sensor to the outside world; the isolation structure is used to absorb and release the stress generated by changes in the external environment; the inner chip structure is used to convert and transmit the pressure signal, thereby realizing pressure measurement. When the external pressure acts on the upper surface of the film structure 2 of the inner chip structure 9, and the lower surface of the film structure 2 is connected to the atmosphere through the atmospheric vent 14 of the frame 13, the film structure 2 will deform, and the piezoresistive resistor 3 will convert the signal and transmit the signal to the external detection circuit through the electrode lead 4.
[0054] The gauge pressure sensor with an isolation structure proposed by the present invention is manufactured into a chip outer frame, an isolation structure and an inner chip structure through an etching process. When the chip outer frame is subjected to stress caused by changes in the external environment, the stress is released and absorbed through the isolation structure. Therefore, the inner chip structure can resist the transmission of stress during the packaging process, eliminating the influence of residual stress generated during the packaging process on the chip performance. At the same time, the gauge pressure sensor with an isolation structure proposed by the present invention can also prevent the influence of external environmental factors on the performance of the inner chip structure during the application process, so that the sensor has strong stability and good repeatability; the present invention also describes the packaging form of the gauge pressure sensor with an isolation structure by using an example. The packaging connects the lower surface of the film structure with the external atmospheric pressure by designing an atmospheric vent on the frame, and connects the lower surface of the cavity structure with the frame by applying adhesive on the lower surface of the inner chip structure, so that the lower surface and upper surface of the film structure are connected to the atmospheric pressure and the environmental pressure respectively, forming a gauge pressure sensor for pressure measurement and conversion. At the same time, compared with the existing packaging, the packaging form is small in size and low in manufacturing cost.
[0055] Therefore, the gauge pressure sensor with an isolation structure proposed in the present invention not only solves the influence of stress generated during the packaging process or changes in the external environment on the performance of the gauge pressure sensor, has a small zero point output, but also reduces the size of the gauge pressure sensor after packaging, reduces the cost, and has broad application prospects.
[0056] The above-described example is only one embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A gauge pressure sensor with an isolation structure, characterized in that: It includes a chip frame, an isolation structure and an inner chip structure; one end of the isolation structure is connected to the chip frame, and the other end is connected to the inner chip structure, that is, it surrounds the outer side of the inner chip structure and the inner side of the chip frame, and includes an isolation suspension beam and a narrow slit; the isolation suspension beam can be in the form of a folded beam or a straight beam; the narrow slit is in a multi-fold form, distributed on the outer side of the inner chip structure and the inner side of the chip frame.
2. A gauge pressure sensor with an isolation structure as claimed in claim 1, characterized in that: The number of isolation beams is ≥1, and they are made by etching process. The number, length and form of the isolation beams can be designed according to the stress caused by the actual manufacturing process or application of the sensor so that the sensor has stress isolation effect; the number of folds of the narrow slit is ≥1.
3. The gauge pressure sensor with an isolation structure as claimed in claim 1, characterized in that: The inner chip structure is located inside the gauge pressure sensor structure, including a thin film structure, a piezoresistive resistor and a cavity structure, and is mainly used to detect pressure signals and convert them into electrical signals for output; the chip outer frame is located at the outermost side of the gauge pressure sensor, including electrode lead terminals and a substrate structure.
4. A packaging structure of a gauge pressure sensor with an isolation structure, comprising an adhesive, a frame, an atmospheric vent, a plastic packaging material, leads, and the gauge pressure sensor with an isolation structure according to any one of claims 1 to 3.
5. The gauge pressure sensor with an isolation structure as claimed in claim 4, characterized in that: The lower surface of the cavity structure in the inner chip structure is connected to the frame, and the upper surface is connected to the lower surface of the film structure in the inner chip structure; the plastic packaging material is connected to the chip outer frame on all sides, and its bottom surface is connected to the frame, thereby protecting the gauge pressure sensor with an isolation structure inside.
6. The gauge pressure sensor with an isolation structure as claimed in claim 4, characterized in that: The atmospheric vent is located on the frame and connected to the lower surface of the cavity structure, and is used to connect the lower surface of the film structure of the inner chip structure to the outside atmosphere, and the upper surface of the film structure to the ambient pressure, to form a gauge pressure sensor structure for pressure testing.
7. The gauge pressure sensor with an isolation structure as claimed in claim 4, characterized in that: The lead is located in the plastic packaging material and is used to connect the electrical signal of the gauge pressure sensor with an external signal; the adhesive is located on the frame and is connected to the area of the lower surface of the cavity structure of the inner chip structure except the atmospheric vent.
8. The gauge pressure sensor with an isolation structure as claimed in claim 4, characterized in that: The chip outer frame of the gauge pressure sensor with an isolation structure is connected to the plastic packaging material on all sides, and the bottom surface is connected to the frame through adhesive. The inner chip structure is separated from the plastic packaging material by the isolation structure, so that the gauge pressure sensor is not affected by the packaging process and changes in the external environment.
9. A method for preparing a gauge pressure sensor with an isolation structure, characterized in that: The following steps are involved: (1) SOI silicon wafer front side oxidation, photolithography, and implantation to form piezoresistive resistors; (2) Photolithography and etching on the front side of the SOI silicon wafer to form electrode lead holes; (3) Metal is sputtered on the front of the SOI silicon wafer, and the metal is photolithographically and etched to form leads and pads; (4) A passivation layer is deposited on the front of the SOI silicon wafer, and an electrode lead interface is formed by photolithography and etching; (5) The front side of the SOI silicon wafer is photolithographically processed and etched to the oxide layer, and beams and narrow slits are formed on the front side; (6) Photolithography and etching of the back side of the SOI silicon wafer until it is penetrated to form isolation cantilever beams, narrow gaps, inner chips and cavity structures; (7) Slicing.