MEMS package structure

Abstract

This invention provides a MEMS packaging structure, including a first substrate and a second substrate. The second substrate and the first substrate are bonded together at a predetermined distance to seal the bonding area into a closed microvacuum cavity. A microvacuum gauge is disposed inside the closed microvacuum cavity to monitor the vacuum level inside the cavity. By incorporating a microvacuum gauge within the MEMS packaging structure, the vacuum level inside the vacuum cavity where the MEMS sensor is located can be monitored in real time and in situ. This allows for determination of whether the vacuum level inside the cavity is within the range required for normal operation of the MEMS sensor, providing timely early warning and enabling appropriate countermeasures to be taken promptly to ensure the continuous and normal operation of the sensor.

Description

Technical Field

[0001] This invention relates to the field of semiconductor sensor technology, and in particular to a MEMS packaging structure. Background Technology

[0002] For many semiconductor sensors, especially MEMS sensors, their performance is affected by the vacuum level they operate in, typically requiring a high vacuum (~10). -2 A high vacuum environment is necessary to achieve the required sensitivity and quality factor. These MEMS devices include inertial sensors such as MEMS gyroscopes and MEMS accelerometers, as well as other types of sensors such as pressure sensors, MEMS micromirrors, and microbolometers. For gyroscopes, increasing the vacuum level within their sealed cavity reduces air damping during operation by decreasing the number of gas molecules inside, thereby achieving a high quality factor and low noise. For accelerometers, changes in vacuum level are a key factor affecting their dynamic response performance; a high vacuum level keeps the air damping of the accelerometer's compression diaphragm at a low level, thus improving sensitivity. For pressure sensors, a high vacuum environment ensures high sensitivity and a high quality factor in device measurements. For MEMS micromirrors, collisions of gas molecules on the micromirror surface significantly affect the device's quality factor, while a high vacuum environment reduces energy loss from the micromirror, thus improving the quality factor. For microbolometers, which absorb infrared energy to cause temperature changes, a vacuum environment results in a longer average molecular free path for particles, which helps suppress gas heat conduction, allowing heat to be primarily conducted through thermal radiation, thereby improving device sensitivity.

[0003] The Q-factor of a MEMS sensor depends not only on the sensor design but also, to a large extent, on the pressure level of the sealed MEMS. To ensure the sensor operates at an ideal state, it is necessary to monitor the vacuum level of the sensor. However, in practical applications, because the packaged sensor is in a sealed state, it is difficult to monitor its internal vacuum level without damaging the sensor. Consequently, the decrease in internal vacuum is only discovered after the sensor malfunctions, by which time it is often too late.

[0004] Therefore, how to provide a MEMS packaging structure to achieve real-time monitoring and control of the airtightness inside the vacuum cavity where microelectronic devices are located, to ensure the normal operation of the devices and reduce measurement errors, has become an important technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a MEMS packaging structure to solve the problem that in the prior art, it is difficult to monitor the vacuum level inside the vacuum cavity where the MEMS sensor is located in real time, which leads to the inability to detect and adjust the vacuum level in time when it drops, thus causing the MEMS sensor to malfunction.

[0006] To achieve the above and other related objectives, the present invention provides a MEMS packaging structure, characterized in that it comprises:

[0007] The first substrate has a first main surface and a second main surface arranged opposite to each other. The first main surface is provided with a first insulating cover layer and a first cavity. A first supporting cover layer is provided in the first cavity. A miniature vacuum gauge is provided in the first supporting cover layer.

[0008] The second substrate has a third main surface and a fourth main surface disposed opposite to each other, and the third main surface is provided with a second insulating cover layer;

[0009] The third main surface of the second substrate is bonded to the first main surface of the first substrate at a predetermined distance to seal the interior of the bonding area into a closed microvacuum cavity; wherein, the closed microvacuum cavity includes the first cavity and a gas molecule channel formed by the predetermined distance between the first substrate and the second substrate, and the gas molecule channel is connected to the first cavity, and the micro vacuum gauge is used to monitor the vacuum level inside the closed microvacuum cavity.

[0010] Optionally, the miniature vacuum gauge includes a MEMS Pirani vacuum gauge, a diode-type vacuum gauge, or a thin-film capacitance gauge vacuum gauge.

[0011] Optionally, the first support cover layer includes a first support body and a first support arm, one end of the first support arm is connected to the first support body, and the other end is connected to the first insulating cover layer of the first substrate. The micro vacuum gauge is disposed in the first support body and extends along the first support arm into the interior of the first insulating cover layer.

[0012] Optionally, the third main surface of the second substrate is provided with a second cavity, and a vacuum degree regulating structure is provided in the second cavity. The third main surface of the second substrate is bonded to the first main surface of the first substrate, and the second cavity is sealed as part of the closed micro vacuum cavity. The second cavity is connected to the first cavity and the gas molecule channel. The vacuum degree regulating structure is used to regulate the vacuum degree in the closed micro vacuum cavity.

[0013] Furthermore, a suspended second support covering layer is provided in the second cavity; the vacuum degree control structure includes a micro heater and a getter film, the micro heater is disposed in the second support covering layer, and the getter film is disposed on the surface of the second support covering layer on the side of the micro heater away from the second cavity.

[0014] Furthermore, the second support cover layer includes a second support body and a second support arm. One end of the second support arm is connected to the second support body, and the other end is connected to the second insulating cover layer of the second substrate. The micro heater is disposed in the second support body and extends along the second support arm into the interior of the second insulating cover layer.

[0015] Furthermore, the material of the micro heater is one or more combinations of titanium, nickel, molybdenum, tungsten, rhodium, platinum, iridium, aluminum, copper, gold, tantalum, chromium, titanium nitride, polycrystalline silicon, monocrystalline silicon, carbon nanotubes, and graphene; the material of the second supporting capping layer is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, alumina, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the getter film is one or more combinations of Ti-based non-evaporable getter materials, Zr-based non-evaporable getter materials, Hf-based non-evaporable getter materials, V-based non-evaporable getter materials, Nb-based non-evaporable getter materials, Ta-based non-evaporable getter materials, Pd-based non-evaporable getter materials, Cr / Ni alloy-based non-evaporable getter materials, and rare earth-based non-evaporable getter materials.

[0016] Furthermore, the MEMS packaging structure also includes a temperature monitoring structure disposed inside the first main surface of the first substrate, for monitoring the temperature inside the sealed micro vacuum cavity to perform temperature compensation correction on the micro vacuum gauge, and to monitor whether the temperature of the micro heater reaches the activation temperature of the getter film.

[0017] Furthermore, the temperature monitoring structure may be a diode, a thermistor, a thermocouple, a thermopile, or a resonator.

[0018] Furthermore, the temperature monitoring structure includes a first N-type doped region, a second N-type doped region, a first P-type doped region, and a second P-type doped region. The first P-type doped region is disposed on the outer periphery of the bottom and side surfaces of the second P-type doped region. The first N-type doped region is disposed on the outer periphery of the bottom and side surfaces of the first P-type doped region. The second N-type doped region extends inward from a portion of the surface of the first N-type doped region and surrounds the outer periphery of the first P-type doped region at intervals.

[0019] Furthermore, the second cavity and the first cavity are spatially misaligned, and the second cavity is spatially corresponding to the temperature monitoring structure. The second cavity and the first cavity are connected through the gas molecule channel.

[0020] Furthermore, the third main surface of the second substrate is provided with a third cavity corresponding to the first cavity space of the first substrate. When the third main surface of the second substrate is bonded to the first main surface of the first substrate, the third cavity is also sealed as part of the sealed micro vacuum cavity. The third cavity is connected to the second cavity, the first cavity and the gas molecule channel. A heat sink is provided on the bottom surface of the third cavity.

[0021] Furthermore, the spatial height of the gas molecule channel is 0.1μm~100μm, and the orthographic projection shape of the gas molecule channel on the plane of the first substrate is circular, rectangular, or polygonal.

[0022] Furthermore, the MEMS packaging structure also includes a MEMS sensor disposed in the first cavity or the second cavity, the MEMS sensor including one or more combinations of MEMS gyroscope, MEMS accelerometer, MEMS pressure sensor, MEMS resonator, and MEMS micromirror.

[0023] Optionally, the first substrate is a single-layer structure or a stacked structure of one or more of the following: a silicon substrate, a SiC substrate, a quartz substrate, a sapphire substrate, or a glass substrate; the second substrate is a single-layer structure or a stacked structure of one or more of the following: a silicon substrate, a SiC substrate, a quartz substrate, a sapphire substrate, or a glass substrate; the material of the first supporting capping layer is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, alumina, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the first insulating capping layer is silicon, oxygen... The material of the first insulating layer is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, aluminum scandium nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the second insulating covering layer is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, aluminum scandium nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the micro vacuum gauge is one or more combinations of titanium, nickel, molybdenum, tungsten, rhodium, platinum, iridium, aluminum, copper, gold, tantalum, chromium, titanium nitride, polycrystalline silicon, monocrystalline silicon, carbon nanotubes, and graphene.

[0024] As described above, the MEMS packaging structure of the present invention, by setting a miniature vacuum gauge inside the MEMS packaging structure, can monitor the vacuum level inside the vacuum cavity where the MEMS sensor is located in real time and in situ. This allows it to determine whether the vacuum level inside the vacuum cavity where the MEMS sensor is located is within the vacuum level range required for the normal operation of the MEMS sensor, thereby playing a timely warning role and enabling timely implementation of corresponding countermeasures to ensure the continuous normal operation of the sensor. Attached Figure Description

[0025] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the embodiments of this application and to illustrate the implementation of this application, together with the textual description, to explain the principles of this application. Obviously, the drawings described below are merely some embodiments of this application.

[0026] Figure 1 The diagram shows a cross-sectional view of an example of the first substrate and the structures formed on its surface and in its bulk before bonding of the MEMS packaging structure of the present invention.

[0027] Figure 2 The diagram shows a cross-sectional view of an example of the second substrate and the structure formed on its surface before bonding of the MEMS packaging structure of the present invention.

[0028] Figure 3 The diagram shown is a cross-sectional schematic of a first example of the MEMS packaging structure of the present invention.

[0029] Figure 4 The diagram shown is a top view of a first example of a micro vacuum gauge representing the MEMS packaging structure of the present invention.

[0030] Figure 5 The diagram shown is a top view of a second example of a micro vacuum gauge representing the MEMS packaging structure of the present invention.

[0031] Figure 6 The diagram shown is a cross-sectional schematic of a second example of the MEMS packaging structure of the present invention.

[0032] Figure 7 The diagram shown is a cross-sectional schematic of a third example of the MEMS packaging structure of the present invention.

[0033] Figure 8 The diagram shown is a top view of a first example of a micro heater representing the MEMS packaging structure of the present invention.

[0034] Figure 9 The diagram shown is a top view of a second example of a micro heater representing the MEMS packaging structure of the present invention.

[0035] Figure 10The diagram shown is a top view of a third example of a micro heater representing the MEMS packaging structure of the present invention.

[0036] Figure 11 The diagram shown is a cross-sectional schematic of the fourth example of the MEMS packaging structure of the present invention.

[0037] Figure 12 The diagram shown is a top view of a first example of a temperature monitoring structure for a MEMS package structure according to the present invention.

[0038] Figure 13 The diagram shown is a top view of a second example of a temperature monitoring structure for a MEMS package structure according to the present invention.

[0039] Figure 14 The diagram shown is a cross-sectional schematic of the temperature monitoring structure of the MEMS packaging structure of the present invention.

[0040] Figure 15 The diagram shown is a cross-sectional schematic of the fifth example of the MEMS packaging structure of the present invention.

[0041] Component designation explanation

[0042] 100 First substrate 101 First Main Page 102 Second Main Page 103 First insulating layer 104 First cavity 105 Miniature vacuum gauge 106 First support covering layer 107 First supporting entity 108 First support arm 109 First Introduction 110 First wire bonding pad 111 Second wire bonding pad 112 Third wire bonding pad 113 Second introduction section 114 First bonding section 200 Second substrate 201 Third Main Face 202 Fourth Main Face 203 Second insulating layer 204 Second bonding section 205 Second cavity 206 Vacuum degree control structure 207 Miniature heater 208 getter film 209 Second support covering layer 210 Second support arm 211 Second supporting entity 213 Third Exit Section 214 Lead wire 215 Lead plate 216 Connecting pads 300 Temperature monitoring structure 301 First N-type doped region 302 Second N-type doped region 303 First P-type doped region 304 Second P-type doped region 305 Fourth Introduction 400 Third cavity 401 heat sink 500，501，502 Electrical connection wires 504 Packaging substrate 600 Sealed micro vacuum chamber 603 gas molecule channels Detailed Implementation

[0043] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0044] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, whole, step, or component, but does not exclude the presence or addition of one or more other features, wholes, steps, or components.

[0045] Features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0046] In the detailed description of embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged and not to scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In actual fabrication, the three-dimensional spatial dimensions of length, width, and depth should be included.

[0047] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one element or feature shown in the accompanying drawings and other elements or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the drawings for devices in use or operation. Furthermore, when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or there may be one or more layers in between.

[0048] In the context of this application, the structure described above the first feature may include embodiments in which the first and second features are formed in direct contact, or embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0049] It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0050] like Figures 1 to 3 As shown, this embodiment provides a MEMS packaging structure, including:

[0051] like Figure 1 As shown, the first substrate 100 has a first main surface 101 and a second main surface 102 disposed opposite to each other. The first main surface 101 is provided with a first insulating cover layer 103 and a first cavity 104. A first supporting cover layer 106 is suspended in the first cavity 104. A miniature vacuum gauge 105 is disposed in the first supporting cover layer 106.

[0052] like Figure 2 As shown, the second substrate 200 has a third main surface 201 and a fourth main surface 202 disposed opposite to each other, and the third main surface 201 is provided with a second insulating cover layer 203;

[0053] like Figure 3 As shown, the third main surface 201 of the second substrate 200 is bonded to the first main surface 101 of the first substrate 100 at a predetermined distance to seal the interior of the bonding area into a closed micro vacuum cavity 600; wherein, the closed micro vacuum cavity 600 includes the first cavity 104 and a gas molecule channel 603 formed by the predetermined distance between the first substrate 100 and the second substrate 200, and the gas molecule channel 603 is connected to the first cavity 104; the micro vacuum gauge 105 is used to monitor the vacuum level inside the closed micro vacuum cavity 600.

[0054] The process by which the micro vacuum gauge 105 monitors the vacuum level inside the sealed micro vacuum cavity 600 is as follows: the reading of the micro vacuum gauge 105 can reflect the vacuum level inside the sealed micro vacuum cavity 600. Specifically, when the reading of the micro vacuum gauge 105 changes, it indicates that the vacuum level inside the sealed micro vacuum cavity 600 has begun to change. By observing the change in the reading of the micro vacuum gauge 105, it can be determined whether the vacuum level inside the sealed micro vacuum cavity 600 is within the preset vacuum level range, that is, within the vacuum level range required for the normal operation of the chip, thereby realizing real-time monitoring of the vacuum level inside the sealed micro vacuum cavity 600.

[0055] The MEMS packaging structure of the present invention, by setting a miniature vacuum gauge inside the MEMS packaging structure, can monitor the vacuum level inside the vacuum cavity where the MEMS sensor is located in real time and in situ. This allows the system to determine whether the vacuum level inside the vacuum cavity where the MEMS sensor is located is within the vacuum level range required for the normal operation of the MEMS sensor, thereby providing a timely warning and enabling timely countermeasures to ensure the continuous normal operation of the sensor.

[0056] The miniature vacuum gauge 105 can be selected from any suitable vacuum gauge for measuring vacuum, such as a MEMS Pirani vacuum gauge, a diode vacuum gauge, or a thin-film capacitance gauge, etc.

[0057] The specific routing of the miniature vacuum gauge 105 within the first support cover layer 106 can be freely designed as needed, and no excessive restrictions are imposed here. As an example, such as... Figure 4 As shown, the first support cover layer 106 can be configured to include a first support body 107 and a first support arm 108. One end of the first support arm 108 is connected to the first support body 107, and the other end is connected to the first insulating cover layer 103 of the first substrate 100. The miniature vacuum gauge 105 is disposed within the first support body 107 and extends along the first support arm 108 into the interior of the first insulating cover layer 103. The arrangement of the miniature vacuum gauge 105 within the first support body 107 can be any suitable form. For example, please refer to [link to example]. Figure 4 and Figure 5 As shown, it is set in a continuous U-shaped broken line form, but it can also be set in other forms according to actual needs, without excessive restrictions. The number of the first support bodies 107 of the miniature vacuum gauge 105 can be selected according to actual needs, such as... Figure 4 There is one in the middle, such as Figure 5 There are three in total. The shape of the first support body 107 can also be adjusted according to usage requirements without changing the longitudinal structure of its heating structure, such as... Figure 4 The center is a square. Figure 5 The design incorporates both square and rectangular shapes. The number of the first support arms 108 ranges from 1 to 100, such as 1, 2, 3, 4, 5, etc., and can be specifically selected according to needs. Figure 4 The number is 4. Figure 5 There can be multiple first support arms 108, and the number of first support arms 108 is not limited to the examples listed here. The shape of the first support arm 108 can be selected in any suitable way, such as a straight line, a broken line, or an arc, etc., as needed, and is not limited to the examples listed here.

[0058] Specifically, the structural parameters such as the area and depth of the first cavity 104 can be determined based on the structure of the miniature vacuum gauge 105 it houses. The main function of the first cavity 104 is to provide a certain amount of space for the miniature vacuum gauge 105, allowing the circuit resistance of the miniature vacuum gauge 105 to become a suspended thin film, thus providing conditions for the operation of the miniature vacuum gauge 105 and monitoring the vacuum level inside the vacuum cavity. The size, area, and other structural parameters of the miniature vacuum gauge 105 can be determined based on the required range of vacuum level to be monitored within the vacuum cavity.

[0059] like Figure 1 , Figure 3 and Figure 4 As shown, in some embodiments, the first substrate 100 is provided with a first lead-out portion 109 and a first wire bonding pad 110. The first lead-out portion 109 is connected to the miniature vacuum gauge 105 and to the first wire bonding pad 110 to realize the electrical lead-out of the miniature vacuum gauge 105, and is connected to the package substrate 504 through an electrical connection line 500, such as... Figure 3 As shown, the electrical leads of the entire device are brought out, facilitating subsequent testing.

[0060] In some embodiments, the material of the first substrate 100 is a single-layer structure or a stacked structure of one or more of the following: silicon substrate, SiC substrate, quartz substrate, sapphire substrate, glass substrate, or other suitable insulating substrate; the material of the second substrate 200 is a single-layer structure or a stacked structure of one or more of the following: silicon substrate, SiC substrate, quartz substrate, sapphire substrate, glass substrate, or other suitable insulating substrate, which can be selected as needed and is not limited to the examples listed herein.

[0061] In some embodiments, the material of the first supporting cover layer 106 is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the first insulating cover layer 103 is silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, aluminum oxide, and silicon oxide. The second insulating cover layer 203 is made of one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel, which can be selected as needed and are not limited to the examples listed here.

[0062] In some embodiments, the material of the micro vacuum gauge 105 is one or more combinations of titanium, nickel, molybdenum, tungsten, rhodium, platinum, iridium, aluminum, copper, gold, tantalum, chromium, titanium nitride, polysilicon, single-crystal silicon, carbon nanotube, and graphene.

[0063] like Figures 1 to 3 As shown, in some embodiments, the first insulating cover layer 103 of the first substrate 100 is provided with a first bonding portion 114, and the second insulating cover layer 203 of the second substrate 200 is provided with a second bonding portion 204 facing the first bonding portion 114. The first substrate 100 and the second substrate 200 are bonded to each other through the first bonding portion 114 and the second bonding portion 204.

[0064] Specifically, in the bonding region, the first insulating cover layer 103 on the first main surface 101 and the second insulating cover layer 203 on the third main surface 201 are in airtight contact, surrounding the sealed micro vacuum cavity 600 and isolating it from the surrounding environment.

[0065] In some embodiments, the bonding types of the first bonding portion 114 and the second bonding portion 204 include, but are not limited to, anodic bonding, eutectic bonding, direct bonding, adhesive bonding, glass slurry bonding, instantaneous liquid phase bonding, metal hot pressing bonding, and diffusion bonding. The specific bonding types can be selected as needed and are not limited to the examples listed herein.

[0066] In some embodiments, the material of the first bonding portion 114 is one or more combinations of silicon, glass, gold, tin, aluminum, germanium, glass paste, and polymer; the material of the second bonding portion 204 is one or more combinations of silicon, glass, gold, tin, aluminum, germanium, glass paste, and polymer, which can be selected as needed and are not limited to the examples listed herein.

[0067] like Figure 6and Figure 7 As shown, in a preferred example, the third main surface 201 of the second substrate 200 is provided with a second cavity 205, and a vacuum degree regulating structure 206 is provided in the second cavity 205. The third main surface 201 of the second substrate 200 is bonded to the first main surface 101 of the first substrate 100, and at the same time, the second cavity 205 is sealed as part of the sealed micro vacuum cavity 600. The second cavity 205 is connected to the first cavity 104 and the gas molecule channel 600. The vacuum degree regulating structure 206 is used to regulate the vacuum degree in the sealed micro vacuum cavity 600.

[0068] The vacuum degree adjustment structure 206 can be arranged opposite to the miniature vacuum gauge 105, such as... Figure 6 As shown, the settings can also be staggered, such as... Figure 7 As shown, since the vacuum degree control structure 206 will cause a local temperature rise when heated, it may affect the accuracy of the vacuum gauge reading. In this embodiment, it is preferable to set the structure in a staggered manner to facilitate the accurate measurement of the vacuum gauge.

[0069] As an example, such as Figure 6 and Figure 7 As shown, the vacuum control structure 206 includes a micro heater 207 and a getter film 208. The micro heater 207 is disposed in a suspended second support cover layer 209 in the second cavity 205, and the getter film 208 is disposed on the surface of the second support cover layer 209 on the side of the micro heater 207 away from the second cavity 205.

[0070] Specifically, the area, depth, and other structural parameters of the second cavity 205 can be determined based on the structure of the micro heater 207 it houses. The main function of the second cavity 205 is to provide space for the micro heater 207, allowing the heater film of the micro heater 207 to become a suspended film, providing space for the movement of gas molecules and ensuring real-time control of the vacuum level inside the vacuum chamber. The size, area, and other structural parameters of the micro heater 207 can be determined based on the range of vacuum levels to be controlled.

[0071] When the reading of the micro vacuum gauge 105 changes, it indicates that the internal vacuum level of the sealed micro vacuum cavity 600 has begun to change. At the same time, it can be determined whether the vacuum level control structure 206 should be activated based on the vacuum level monitoring results. For example, if the change in the reading of the micro vacuum gauge 105 exceeds a preset range, it is determined that the vacuum level control structure 206 needs to be activated. By energizing the micro heater 207 of the vacuum level control structure 206, its temperature rises, and the getter film 208 starts to work, adsorbing gas molecules inside the sealed micro vacuum cavity 600, allowing the sealed micro vacuum cavity 600 to return to the required vacuum level, thereby providing the best working environment for microelectronic devices to ensure operational reliability and service life.

[0072] As an example, the specific routing of the microheater 207 within the second support cover layer 209 can be freely designed as needed, and no excessive restrictions are imposed here. For example, please refer to... Figure 8 The second support cover layer 209 includes a second support body 211 and a second support arm 210. One end of the second support arm 210 is connected to the second support body 211, and the other end is connected to the second insulating cover layer 203 of the second substrate 200. The micro heater 207 is disposed within the second support body 211 and extends along the second support arm 210 into the interior of the second insulating cover layer 203. The arrangement of the micro heater 207 within the second support body 211 can be any suitable form. For example, please refer to [link to example]. Figures 8 to 10 As shown, it is set in the form of a continuous U-shaped broken line, but it can also be set in other forms according to actual needs. There are no excessive restrictions here.

[0073] In some embodiments, the shape of the second support body 211 of the micro heater 207 can be adjusted according to usage requirements without changing the longitudinal structure of its heating structure. The second support arm 210 of the micro heater 207 can be in a straight line, a broken line, or an arc shape, etc., and can be selected as needed, and is not limited to the examples listed here. The number of the second support arms 210 ranges from 1 to 100, such as 1, 2, 3, 4, 5, etc., and can be selected as needed, and is not limited to the examples listed here. As an example, such as Figure 8 As shown, the second support body 211 of the micro heater 207 is rectangular, the second support arm 210 of the micro heater 207 is zigzag-shaped, and the number of the second support arms 210 is 4.

[0074] As an example, such as Figure 9As shown, when the second support arm 210 of the micro heater 207 is a polygonal shape, the corners of the micro heater 207 and the second support arm 210 are preferably rounded, which helps to improve stress concentration.

[0075] As an example, the number of the micro heaters 207 can be multiple, such as 2, 3, 4, 5, or 6, etc. Figure 9 As shown, the number of miniature heaters 207 is two, as follows: Figure 10 As shown, there are three miniature heaters 207.

[0076] In some embodiments, such as Figures 6 to 8 As shown, the second substrate 200 has a third lead-out portion 213 and a connecting pad 216, and the first substrate 100 has a second wire bonding pad 111. The third lead-out portion 213 is connected to the vacuum degree control structure 206 and is connected to the second wire bonding pad 111 through the connecting pad 216 to realize the electrical lead-out of the vacuum degree control structure 206. Furthermore, it is connected to the packaging substrate 504 through an electrical connection line 501 to realize the electrical lead-out of the entire device, facilitating subsequent testing. For example, as shown... Figure 8 As shown, there are two third lead-out sections 213, which are respectively connected to the positive and negative terminals of the micro heater 207. Each third lead-out section 213 includes a lead wire 214 and a lead plate 215. The second support arm 210 serves as a channel for laying the lead wire 214 and provides a certain support strength for the second support body 211 supporting the micro heater 207 to prevent collapse.

[0077] In some embodiments, the material of the micro heater 207 is one or more combinations of titanium, nickel, molybdenum, tungsten, rhodium, platinum, iridium, aluminum, copper, gold, tantalum, chromium, titanium nitride, polycrystalline silicon, monocrystalline silicon, carbon nanotubes, and graphene; the material of the second support cover layer 209 is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel, which can be selected as needed and are not limited to the examples listed herein.

[0078] In some embodiments, the material of the getter film 208 is one or more combinations of Ti-based non-evaporable getter materials, Zr-based non-evaporable getter materials, Hf-based non-evaporable getter materials, V-based non-evaporable getter materials, Nb-based non-evaporable getter materials, Ta-based non-evaporable getter materials, Pd-based non-evaporable getter materials, Cr / Ni alloy-based non-evaporable getter materials, and rare earth-based non-evaporable getter materials. The specific material can be selected as needed and is not limited to the examples listed herein.

[0079] In some embodiments, the material of the second support cover layer 209 is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel, which may be selected as needed and are not limited to the examples listed herein.

[0080] In some embodiments, such as Figure 11 As shown, the MEMS packaging structure also includes a temperature monitoring structure 300, which is disposed inside the first main surface 101 of the first substrate 100. It is used to monitor the temperature inside the sealed micro vacuum cavity 600 to perform temperature compensation correction on the micro vacuum gauge 105, thereby achieving accurate measurement of the vacuum level inside the cavity. At the same time, it can monitor the temperature of the micro heater 207 to determine whether the activation temperature of the getter film 208 has been reached.

[0081] like Figure 11 As shown, when the second cavity 205 and the first cavity 104 are spatially misaligned, the second cavity 205 is spatially corresponding to the temperature monitoring structure 300, and the second cavity 205 and the first cavity 104 are connected through the gas molecule channel 603. In some embodiments, when the second cavity 205 and the first cavity 104 are spatially aligned, the second cavity 205 is spatially misaligned with the temperature monitoring structure 300. In this embodiment, it is preferable that the second cavity 205 and the temperature monitoring structure 300 are spatially corresponding, so that the temperature monitoring structure 300 can more accurately monitor the temperature of the micro heater 207, and make a more accurate judgment on whether the activation temperature of the getter film 208 has been reached. At the same time, the gas molecule channel 603 solves the problem of maintaining the same vacuum level inside the first cavity 104 and the second cavity 205, making the MEMS packaging structure more compact, the cost lower, and suitable for more microelectronic devices.

[0082] The type of temperature monitoring structure 300 is not limited and can be selected according to actual needs, such as diode, thermistor, thermocouple, thermopile or resonator.

[0083] As an example, such as Figures 11 to 14As shown, the temperature monitoring structure 300 includes a first N-type doped region 301, a second N-type doped region 302, a first P-type doped region 303, and a second P-type doped region 304. The first P-type doped region 303 is disposed on the outer periphery of the bottom and side surfaces of the second P-type doped region 304. The first N-type doped region 301 is disposed on the outer periphery of the bottom and side surfaces of the first P-type doped region 303. The second N-type doped region 302 extends inward from a portion of the surface of the first N-type doped region 301 and surrounds the outer periphery of the first P-type doped region 303 at intervals. The doping concentration of the second N-type doped region 302 is greater than that of the first N-type doped region 301, and the doping concentration of the second P-type doped region 304 is greater than that of the first P-type doped region 303, thereby reducing the bulk equivalent resistance in the circuit and achieving the function of electrical lead-out. The short distance between the second N-type doped region 302 and the second P-type doped region 304 reduces the bulk equivalent resistance, which helps improve the linearity and accuracy of temperature monitoring. A PN junction is formed at the interface between the first N-type doped region 301 and the first P-type doped region 303. Its forward bias voltage under constant current drive changes linearly with temperature, thus it can be used for temperature monitoring. The positions of the N-type and P-type doped portions can be flexibly interchanged and adjusted, depending on the specific needs, and are not limited to the examples listed here. The shape of the temperature monitoring structure 300 is not excessively limited and can be selected according to actual needs; for example, it can be as follows... Figure 12 The circle shown, or as shown Figure 13 The rectangle shown.

[0084] like Figure 11 As shown, in some embodiments, the first substrate 100 is provided with a second lead-out portion 113, a third wire bonding pad 112, and a fourth lead-out portion 305. The fourth lead-out portion 305 is disposed on the upper surface of the first insulating cover layer 103 and extends inward to the second N-type doped layer 302 and the second P-type doped layer 304, respectively. The second lead-out portion 113 is disposed inside the first insulating cover layer 103 and connects the fourth lead-out portion 305 to the third wire bonding pad 112 to realize the electrical lead-out of the temperature monitoring structure 300. It is also connected to the packaging substrate 504 through an electrical connection line 502 to realize the electrical lead-out of the entire device, which facilitates subsequent testing.

[0085] In some embodiments, the first bonding portion 114, the first wire bonding pad 110, the second wire bonding pad 111, the third wire bonding pad 112 and the fourth lead-out portion 305 of the temperature monitoring structure 300 are located in the same material layer, and the second bonding portion 204 and the connecting pad 216 are located in the same material layer.

[0086] In some embodiments, in the region where the gas molecule channel 603 is located, neither the first insulating cover layer 103 nor the second insulating cover layer 203 may be etched. In other embodiments, in the region where the gas molecule channel 603 is located, at least one of the first insulating cover layer 103 and the second insulating cover layer 203 is etched to a certain depth so that the final gas molecule channel 603 has a greater height.

[0087] In some embodiments, the orthographic projection shape of the gas molecule channel 603 onto the plane of the first substrate 100 is circular, rectangular, or polygonal. The height of the gas molecule channel 603 ranges from 0.1 μm to 100 μm, such as 0.1 μm, 1 μm, 10 μm, 20 μm, 40 μm, 60 μm, 80 μm, 90 μm, 100 μm, etc. The specific height can be selected as needed and is not limited to the examples listed here.

[0088] In some embodiments, such as Figure 15As shown, the third main surface 201 of the second substrate 200 is provided with a third cavity 400 corresponding to the space of the first cavity 104 of the first substrate 100. When the third main surface 201 of the second substrate 200 is bonded to the first main surface 101 of the first substrate 100, the third cavity 400 is also sealed as part of the sealed microvacuum cavity 600. The third cavity 400 is connected to the second cavity 205, the first cavity 104, and the gas molecule channel 603. A heat sink 401 is provided on the bottom surface of the third cavity 400. The heat sink 401 can reduce the mean free path of molecular collisions, enhance the performance of the micro vacuum gauge 105 in the first cavity 104, and improve the measurement accuracy of the micro vacuum gauge 105. At this time, the first cavity 104, the third cavity 400, the gas molecule channel 603, and the second cavity 205, which are connected in sequence, together constitute the sealed microvacuum cavity 600. By employing a combined structure of the micro vacuum gauge 105, the vacuum degree control structure 206, and the temperature monitoring structure 300, it is possible to achieve real-time, in-situ, precise monitoring of the vacuum degree within the sealed micro vacuum cavity 600, while also enabling online control of the vacuum degree within the sealed micro vacuum cavity 600. Specifically, the micro vacuum gauge 105 is used for real-time, in-situ monitoring of the vacuum degree within the sealed micro vacuum cavity 600; the combination of the micro heater 207 and the getter film 208 enables online control of the vacuum degree within the sealed micro vacuum cavity 600; and the temperature monitoring structure 300... This system enables monitoring of the ambient temperature within the sealed micro-vacuum cavity 600 to perform temperature compensation correction on the micro-vacuum gauge 105, thereby improving monitoring accuracy. Simultaneously, it monitors whether the temperature of the micro-heater 207 reaches the activation temperature of the getter film 208. This allows for real-time, in-situ, precise monitoring and online control of the vacuum level within the sealed micro-vacuum cavity 600. The system is independent of its components, with a simple and compact structure, compatible with other sensor manufacturing processes. It is suitable for various MEMS devices requiring vacuum maintenance, providing greater design flexibility and a wide range of applications.

[0089] The MEMS packaging structure also includes a MEMS sensor (not shown in the figure) disposed in the first cavity 104 or the second cavity 205. The MEMS sensor includes one or more combinations of MEMS gyroscope, MEMS accelerometer, MEMS pressure sensor, MEMS resonator, and MEMS micromirror. The specific selection can be made as needed and is not limited to the examples listed here.

[0090] In summary, this invention provides a MEMS packaging structure. By incorporating a miniature vacuum gauge within the MEMS packaging structure, the vacuum level inside the vacuum chamber where the MEMS sensor is located can be monitored in real time and in situ. This allows for the determination of whether the vacuum level inside the vacuum chamber is within the range required for the normal operation of the MEMS sensor, thus providing timely early warning and enabling appropriate countermeasures to be taken promptly to ensure the continuous and normal operation of the sensor. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0091] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A MEMS packaging structure, characterized in that, include: The first substrate has a first main surface and a second main surface arranged opposite to each other. The first main surface is provided with a first insulating cover layer and a first cavity. A first supporting cover layer is provided in the first cavity. A miniature vacuum gauge is provided in the first supporting cover layer. The second substrate has a third main surface and a fourth main surface disposed opposite to each other, and the third main surface is provided with a second insulating cover layer; The third main surface of the second substrate is bonded to the first main surface of the first substrate at a predetermined distance to seal the interior of the bonding area into a closed microvacuum cavity; wherein, the closed microvacuum cavity includes the first cavity and a gas molecule channel formed by the predetermined distance between the first substrate and the second substrate, and the gas molecule channel is connected to the first cavity, and the micro vacuum gauge is used to monitor the vacuum level inside the closed microvacuum cavity.

2. The MEMS packaging structure according to claim 1, characterized in that: The miniature vacuum gauge includes a MEMS Pirani vacuum gauge, a diode-type vacuum gauge, or a thin-film capacitance gauge vacuum gauge.

3. The MEMS packaging structure according to claim 1, characterized in that: The first support cover layer includes a first support body and a first support arm. One end of the first support arm is connected to the first support body, and the other end is connected to the first insulating cover layer of the first substrate. The micro vacuum gauge is disposed in the first support body and extends along the first support arm into the interior of the first insulating cover layer.

4. The MEMS packaging structure according to claim 1, characterized in that: The third main surface of the second substrate is provided with a second cavity, and a vacuum degree regulating structure is provided in the second cavity. The third main surface of the second substrate is bonded to the first main surface of the first substrate, and at the same time, the second cavity is sealed as part of the sealed micro vacuum cavity. The second cavity is connected to the first cavity and the gas molecule channel. The vacuum degree regulating structure is used to regulate the vacuum degree in the sealed micro vacuum cavity.

5. The MEMS packaging structure according to claim 4, characterized in that: The second cavity is provided with a suspended second support covering layer; the vacuum degree control structure includes a micro heater and a getter film, the micro heater is disposed in the second support covering layer, and the getter film is disposed on the surface of the second support covering layer on the side of the micro heater away from the second cavity.

6. The MEMS packaging structure according to claim 5, characterized in that: The second support cover layer includes a second support body and a second support arm. One end of the second support arm is connected to the second support body, and the other end is connected to the second insulating cover layer of the second substrate. The micro heater is disposed in the second support body and extends along the second support arm into the interior of the second insulating cover layer.

7. The MEMS packaging structure according to claim 5, characterized in that: The micro heater is made of one or more of the following materials: titanium, nickel, molybdenum, tungsten, rhodium, platinum, iridium, aluminum, copper, gold, tantalum, chromium, titanium nitride, polycrystalline silicon, monocrystalline silicon, carbon nanotubes, and graphene. The second support capping layer is made of one or more of the following materials: silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel. The getter film is made of one or more of the following materials: Ti-based non-evaporable getter material, Zr-based non-evaporable getter material, Hf-based non-evaporable getter material, V-based non-evaporable getter material, Nb-based non-evaporable getter material, Ta-based non-evaporable getter material, Pd-based non-evaporable getter material, Cr / Ni alloy-based non-evaporable getter material, and rare earth-based non-evaporable getter material.

8. The MEMS packaging structure according to claim 5, characterized in that: The MEMS packaging structure also includes a temperature monitoring structure disposed inside the first main surface of the first substrate. The temperature monitoring structure is used to monitor the temperature inside the sealed micro vacuum cavity to perform temperature compensation correction on the micro vacuum gauge and to monitor whether the temperature of the micro heater reaches the activation temperature of the getter film.

9. The MEMS packaging structure according to claim 8, characterized in that: The types of temperature monitoring structures include diodes, thermistors, thermocouples, thermopile, or resonators.

10. The MEMS packaging structure according to claim 8, characterized in that: The temperature monitoring structure includes a first N-type doped region, a second N-type doped region, a first P-type doped region, and a second P-type doped region. The first P-type doped region is disposed on the outer periphery of the bottom and side surfaces of the second P-type doped region. The first N-type doped region is disposed on the outer periphery of the bottom and side surfaces of the first P-type doped region. The second N-type doped region extends inward from a portion of the surface of the first N-type doped region and surrounds the outer periphery of the first P-type doped region at intervals.

11. The MEMS packaging structure according to claim 8, characterized in that: The second cavity and the first cavity are spatially misaligned, and the second cavity is spatially corresponding to the temperature monitoring structure. The second cavity and the first cavity are connected through the gas molecule channel.

12. The MEMS packaging structure according to claim 11, characterized in that: The third main surface of the second substrate is provided with a third cavity corresponding to the first cavity space of the first substrate. When the third main surface of the second substrate is bonded to the first main surface of the first substrate, the third cavity is also sealed as part of the sealed micro vacuum cavity. The third cavity is connected to the second cavity, the first cavity and the gas molecule channel. A heat sink is provided on the bottom surface of the third cavity.

13. The MEMS packaging structure according to claim 1, characterized in that: The spatial height of the gas molecule channel is 0.1μm~100μm, and the orthographic projection shape of the gas molecule channel on the plane of the first substrate is circular, rectangular or polygonal.

14. The MEMS packaging structure according to claim 4, characterized in that: The MEMS packaging structure also includes a MEMS sensor disposed in the first cavity or the second cavity, wherein the MEMS sensor includes one or more combinations of MEMS gyroscope, MEMS accelerometer, MEMS pressure sensor, MEMS resonator, and MEMS micromirror.

15. The MEMS packaging structure according to claim 1, characterized in that: The first substrate is a single-layer structure or a stacked structure of one or more of the following: silicon substrate, SiC substrate, quartz substrate, sapphire substrate, or glass substrate; the second substrate is a single-layer structure or a stacked structure of one or more of the following: silicon substrate, SiC substrate, quartz substrate, sapphire substrate, or glass substrate; the material of the first supporting capping layer is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, scandium aluminum nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the first insulating capping layer is silicon or silicon oxide. The material of the first insulating layer is one or more combinations of silicon nitride, aluminum nitride, aluminum scandium nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the second insulating covering layer is one or more combinations of silicon, silicon oxide, silicon nitride, aluminum nitride, aluminum scandium nitride, aluminum oxide, polytetrafluoroethylene, polyamide, polyimide, parylene, and hydrogel; the material of the micro vacuum gauge is one or more combinations of titanium, nickel, molybdenum, tungsten, rhodium, platinum, iridium, aluminum, copper, gold, tantalum, chromium, titanium nitride, polycrystalline silicon, monocrystalline silicon, carbon nanotubes, and graphene.

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