JP5325535B2 - Sensor device and manufacturing method thereof - Google Patents

Description

  The present invention relates to a composite sensor device including an angular velocity sensor and an acceleration sensor, and a manufacturing method thereof.

  As this type of conventional composite physical quantity sensor, for example, there is a composite sensor element disclosed in Japanese Patent No. 3435665 (Patent Document 1). A typical embodiment structure of this composite sensor element is shown in FIG. This composite sensor element is a structure in which a glass substrate and a silicon substrate are bonded and sealed by micromachining technology applying semiconductor manufacturing process technology. A fixed electrode and an electrode pad are formed on the upper and lower surfaces of the glass substrate, respectively, and conductive wiring for conducting both is embedded so as to penetrate the upper and lower surfaces of the glass substrate. The silicon substrate is composed of a single-crystal silicon substrate with depressions formed on both upper and lower surfaces, and a glass substrate and a silicon substrate are anodically bonded in a reduced-pressure atmosphere so that a pressure vessel formed on the inner side is sealed under reduced pressure. In addition, a sensor having a vibration structure is provided therein. A part of the glass substrate is provided with a ventilation path communicating with the outside air and the hermetic sealing portion, and the pressure vessel interior is maintained at substantially atmospheric pressure by the sealing member disposed in the groove. It has become.

Japanese Patent No. 3435665

  In Patent Document 1 described above, the entire sensor element is strictly protected from the outside air in order to ensure that long-term reliability is ensured so that the physical quantity sensor disposed in the substantially atmospheric pressure container does not come into contact with the outside air having a poor sensor use environment. The mounting structure needs to be installed outside the sensor element. As a result, the entire mounting structure becomes large and the cost may increase. Known mounting structures include a structure in which a sensor element is installed in a metal container and sealed by welding with a metal lid, and a structure in which a solder material is sealed in a ceramic container. This leads to an increase in cost, and there is a problem in that the advantage of mounting the sensor element mounting structure on the wafer cannot be fully exhibited.

  Furthermore, when sealing the groove communicating with the outside air provided in a part of the glass substrate and the hermetic sealing portion with the sealing member, the impurity gas contained in the sealing member is mixed into the substantially atmospheric pressure container. There has been a problem of reducing the reliability of the sensor element itself.

  A first object of the present invention is to provide a sensor mounting structure that solves the above-described problems, is small and inexpensive, and can ensure long-term reliability.

  A second object of the present invention is to provide a wafer bonding mounting method that realizes a sensor mounting structure that is small and inexpensive and ensures long-term reliability.

The above-mentioned purpose is that the angular velocity sensor and the acceleration sensor are sealed in the pressure vessel with different gas pressures, and there is a groove connected from the inside of the pressure vessel to the outside at the bonding interface with the sealing cap on the one sensor substrate side, The groove is buried without using a joining member for joining the sensor substrate and the sealing cap by deformation and flow of the sealing cap material.

  According to the sensor mounting structure of the first to third aspects of the present invention, it is possible to realize a sensor that is small and inexpensive and ensures long-term reliability.

  Further, according to the wafer bonding and mounting method of the fourth and fifth aspects of the present invention, it is possible to realize a sensor mounting structure that is small and inexpensive and ensures long-term reliability.

  Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. The same reference numerals in the drawings of the respective embodiments indicate the same or equivalent. In addition, this invention includes making it more effective by combining each embodiment suitably.

(First embodiment)
A sensor mounting structure according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of the entire sensor mounting structure of this embodiment. 2 is a plan view showing a mounting structure of the sensor element 1 in which the exterior package 5 is omitted from the sensor mounting structure of FIG. FIG. 3 is a plan view showing a mounting structure of the sensor element 1 of another form in which the exterior package 5 is omitted from the sensor mounting structure of FIG.

  The sensor mounting structure of this embodiment shown in FIG. 1 is a mounting structure of a composite sensor of an angular velocity sensor and an acceleration sensor. This sensor mounting structure includes a sensor element 1, an integrated circuit 2 that controls driving and sensing of the sensor element, an intermediate wiring 31 that electrically connects the sensor element 1 and the integrated circuit 2, an external connection terminal 4, It is configured to include an intermediate wiring 32 that electrically connects the external connection terminal 4 and the integrated circuit, and an exterior package 5 that includes the entire components. In the present embodiment, the integrated circuit 2, the intermediate wirings 31 and 32, the external connection terminals 4, and the exterior package 5 have a known structure, and are not limited to the structure and method disclosed in this figure.

  Next, a detailed configuration of the sensor element 1 that is the central portion of the present embodiment will be described. The sensor element 1 includes a sensor substrate 12 that supports the sensor 11, a sealing cap 13 that encloses the sensor in a vacuum-cleaned atmosphere, and a bonding frame 14 on which the sensor substrate 12 and the sealing cap 13 are bonded. Is done. Further, a groove 15 which is the heart of the present invention is formed in a part of the joining frame 14.

  Next, the planar structure of the sensor element 1 of the present embodiment will be described with reference to FIG. An angular velocity sensor 11a and an acceleration sensor 11b are arranged in pressure vessels 16a and 16b sealed with a joint frame 14. Here, the acceleration sensor 11b is configured to detect acceleration in one direction and acceleration in a direction orthogonal thereto by two sensors, but various other configurations are conceivable.

  The pressure vessels 16a and 16b are sealed after being evacuated to high vacuum, or are replaced and sealed with a high purity inert gas such as argon. As an example of the internal pressure, several hundred Pa is set as the internal pressure of the pressure vessel 16a in which the angular velocity sensor 11a is arranged, and several hundred hPa is set as the internal pressure in the pressure vessel 16b in which the acceleration sensor 11b is arranged. These setpoints are preferably determined by the operating pressure suitable for each designed sensor.

  The groove 15 which is the heart of the present invention is formed in a part of the joint frame 14 so as to be connected to the outside of the sensor element 1 from the acceleration sensor 11b, for example. The planar shape of the groove is not limited to the embodiment shown in FIG. 2, but the dimension is appropriately determined depending on the material characteristics of the sealing cap 13 in the wafer mounting method described later.

  In the present embodiment shown in FIG. 1 and FIG. 2, each sensor is sealed in a pressure vessel replaced with high vacuum or high purity inert gas, so that an operation state suitable for each sensor can be set. And stable sensing performance. Since the groove 15 is completely sealed from the outside by the material of the sealing cap 13, the sensor element 1, the integrated circuit 2, and the intermediate wirings 31 and 32 are connected to the outside as the exterior package 5 shown in FIG. It is possible to use a simple and low-cost structure, for example, resin sealing, which is sufficient only for the function of mounting without contact.

  FIG. 3 shows another mounting structure of the sensor element 1. In this embodiment, the angular velocity sensor 11a is disposed in the innermost part of the element, and is disposed in the order of the joint frame 14a, the acceleration sensor 11b, and the joint frame 14b toward the outer periphery, and a part of the outermost joint frame 14b. A groove 15 is disposed.

  In this embodiment, as in the embodiment shown in FIG. 2, several hundred Pa is used as the internal pressure of the pressure vessel 16a in which the angular velocity sensor 11a is arranged, and several hundred hPa is used as the internal pressure in the pressure vessel 16b in which the acceleration sensor 11b is arranged. Is set.

  In this embodiment, since the angular velocity sensor 11a is completely included inside the acceleration sensor 11b, the pressure difference applied to the joint frame 14a that partitions the angular velocity sensor 11a and the acceleration sensor 11b is several hundreds hPa. On the other hand, in the embodiment shown in FIG. 2, the pressure difference applied to the joint frame 14 that partitions the angular velocity sensor 11a and the outside is about 1000 hPa. Therefore, the present embodiment shown in FIG. It is possible to realize a sensor mounting structure in which the outside air leaks into 16a and the long-term reliability of the angular velocity sensor 11a is more excellent.

(Second Embodiment)
Next, a sensor mounting structure according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view of the back-side drawer mounting structure in the mounting structure of the sensor element 1 in which the exterior package 5 and the sealing cap 13 are omitted from the sensor mounting structure of FIG. In the present embodiment, the positional relationship between the wiring lead electrode 19 and the sealing cap 13 on the back surface of the sensor substrate 12 formed in the sensor element 1 will be described.

  The sensor element 1 is configured to include a sensor substrate 12 that supports the sensor 11, a sealing cap 13 that encloses the sensor in a vacuum-cleaned atmosphere, and a bonding frame 14 to which the sensor substrate 12 and the sealing cap 13 are bonded. The Further, a groove 15 is formed in a part of the joining frame 14.

  The sensor 11 includes an island electrode portion 111 and a vibrating portion 112. A polycrystalline silicon thin film 113a is formed on the surface of the island electrode portion 111 and the bonding frame 14, and the surface and the sealing cap 13 are bonded to each other. A continuous through hole is formed in the island electrode part 111 and the sensor substrate 12 and is electrically connected from the surface of the island electrode part 111 to the wiring extraction electrode 19 on the back side of the sensor substrate 12 through the inner wall of the through hole. Thus, the polycrystalline silicon thin film 113b is formed. With the above configuration, electric power is supplied from the wiring extraction electrode 19 on the back surface of the sensor substrate 12 to the island electrode unit 111 of the sensor 11, and the vibration unit 112 is driven to detect a physical quantity.

  In the present embodiment, when the sealing cap 13 is bonded to the bonding frame 14 and the polycrystalline silicon thin film 113a formed on the surface of the island electrode portion 111, the groove 15 formed in the bonding frame 14 is formed of the sealing cap 13 material. The pressure vessel 16 is formed by being embedded and completely sealed by deformation of the glass. At the same time, in the present embodiment, even if polishing marks (scratches), crystal grain boundaries, dust, or the like remain on the facing surfaces of the island electrode portion 111 and the sealing cap 13 of the polycrystalline silicon thin film 113a, Therefore, it is not necessary to manage the surface properties of the island electrode portion 111 and the polycrystalline silicon thin film 113a smoothly and cleanly, which is effective in reducing the cost of the process.

  In the sensor mounting structure, whether or not the invention of the present embodiment is implemented can be easily confirmed because the sealing cap 13 is deformed at a position corresponding to the pressure vessel to form a concave surface.

(Third embodiment)
Next, a sensor mounting structure according to a third embodiment of the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view of the surface drawer bonding mounting structure in the mounting structure of the sensor element 1 in which the exterior package and the sealing cap are omitted from the sensor mounting structure of FIG.

  The sensor element 1 is configured to include a sensor substrate 12 that supports the sensor 11, a sealing cap 13 that encloses the sensor in a vacuum-cleaned atmosphere, and a bonding frame 14 to which the sensor substrate 12 and the sealing cap 13 are bonded. The Further, a groove 15 is formed in a part of the joining frame 14.

  The sensor 11 includes an island electrode portion 111 and a vibrating portion 112, and the surface of the island electrode portion 111 and the joining frame 14 and the sealing cap 13 are bonded and joined. In the present embodiment, a through hole is formed in a part of the surface of the sealing cap 13 that is in contact with the island electrode portion 111, and electrically from the surface of the sealing cap 13 to the island electrode portion 111 via the inner wall of the through hole. A wiring lead electrode 19 is formed so as to be conductive. With the above configuration, electric power is supplied from the wiring extraction electrode 19 on the surface of the sealing cap 13 to the island electrode part 111 of the sensor 11, and the vibration part 112 is driven to detect the physical quantity.

  In this embodiment, when the sealing cap 13 is bonded to the bonding frame 14 and the surface of the island electrode portion 111, the groove 15 formed in the bonding frame 14 is embedded by deformation of the glass that is the material of the sealing cap 13. Completely sealed, the pressure vessel 16 is formed. At the same time, in the present embodiment, even if polishing marks or dust remain on both opposing surfaces of the island electrode portion 111 and the sealing cap 13, the surface is sealed so that the unevenness thereof is embedded. Therefore, it is not necessary to manage the surface properties of the island electrode part 111 and the sealing cap 13 smoothly and cleanly, which is effective in reducing the cost of the process.

  In the present embodiment, since a through hole is formed in the sealing cap 13, polishing marks (scratches) and dust are likely to remain on the surface of the sealing cap 13. FIG. 6 is an optical microscope magnified image showing an example of a scratch defect structure remaining on the surface of the sealing cap wafer. Even if there are such irregularities on the joint surface, they are joined so that they are embedded, and a complete sealing structure can be realized.

  Also in this sensor mounting structure, whether or not the invention of the present embodiment is implemented can be easily confirmed because the sealing cap 13 is deformed at a position corresponding to the pressure vessel to form a concave surface. .

(Fourth embodiment)
Next, a sensor mounting structure according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view of a sensor element mounting structure using a joining member.

  In the present embodiment, the sensor mounting structure of the second embodiment shown in FIG. 4 is bonded between the sealing cap 13 and the polycrystalline silicon thin film 113 formed on the surface of the bonding frame 14 and the island electrode portion 111. The point which arrange | positions the member 17 and fuses the said joining member differs. As specific examples of the joining member, low melting point glass and eutectic solder are known.

  In the present embodiment, since the joining member is in a molten state and has high fluidity, it is easy to be embedded in the groove. Therefore, there is an advantage that the bonding load can be reduced and the distortion of the wafer can be suppressed.

(Fifth embodiment)
Next, a wafer bonding / mounting method according to a fifth embodiment of the present invention will be described with reference to FIGS. The sensor element 1 shown in FIG. 1 is manufactured using a wafer bonding mounting method. In this method, the sensor 11 is formed on a SOI (Si on Insulator) wafer using a micromachining technique, and a certain movement capability under a temperature near a softening temperature and under an electric field application condition. The sealing cap 13 made of a glass substrate containing ionized molecules having a position is properly aligned, then the substrate is anodically bonded, and finally cut into individual sensor elements 1 by dicing.

  Next, the joining process which is an important point of the present invention will be described with reference to FIG. A groove 15 is formed at a position that is in close contact with the sealing cap 13 shown in FIG. 1 and separates the outside air from the acceleration sensor 11b of the joint frame 14 shown in FIG. 2, and then the angular velocity sensor 11a and the acceleration sensor 11b are connected. When sealing the pressure vessels 16a and 16b by bonding, at least two stages of bonding recipes are executed.

  First, as a first step, wafer bonding is performed under known anodic bonding conditions. As an example of the bonding conditions, a bonding temperature of about 400 ° C. or less, a bonding voltage of 100 to 1000 V, a bonding load under a clean reduced-pressure atmosphere in which the gas pressure is replaced with several hundred Pa as an example of a chemically inert argon gas Is performed without positive application.

  By this process, the part other than the groove 15 in the joining frame 14 is completely joined, so that only the angular velocity sensor 11a is sealed in a reduced pressure state of several hundred Pa or less.

  After the first stage bonding is completed, the wafer bonding is continued under the special anodic bonding conditions according to the present invention in the second stage. As a second bonding condition, a bonding pressure of about 10 kN or more is applied in the vicinity of the softening temperature of the sealing cap at a bonding temperature of about 450 ° C. or more in an atmosphere of several hundred hPa with argon gas, for example, in an atmosphere of argon gas. By doing so, anodic bonding is performed at high temperature and high load.

  By this process, anodic bonding proceeds while the groove 15 of the bonding frame 14 is filled with the deformed sealing cap material, and the acceleration sensor 11b is sealed in a reduced pressure state close to atmospheric pressure of several hundred hPa or less.

  According to the wafer bonding and mounting method of the fifth embodiment of the present invention, pressure vessels having different internal gas pressures are formed in a series of multistage bonding processes, and each sensor functions under appropriate operating conditions. Thus, a highly functional composite sensor element can be obtained.

  Next, an example of the effect of the present embodiment will be described with reference to FIGS. FIG. 8 is a graph showing the junction temperature dependence of the leak rate (external air leakage rate) to a high vacuum vessel sealed with an anodic bond at high temperature and high load. In the condition range where the bonding temperature is 450 ° C. or more and the bonding load is 15 kN, the leak rate is almost the same regardless of the width of the bonding frame of 100 to 500 μm, and a strong bonding sealing is realized.

  FIG. 9 is a graph showing the junction load dependence of the leak rate (external air leakage rate) to a high vacuum vessel sealed with an anodic bond at high temperature and high load. In the condition range where the bonding load is 10 kN or more and the bonding temperature is 500 ° C., the leak rate is almost the same regardless of the width of the bonding frame of 100 to 500 μm, and a strong bonding sealing is realized.

  By providing a groove in a part of the joining frame and the two-step joining method of the known joining conditions and the high temperature / high load joining conditions as described above, a plurality of inert gas pressure vessels having different reduced pressures are sealed. It becomes possible to realize a stopped composite sensor having excellent reliability at low cost.

  Furthermore, according to the present invention, since the junction width at the island electrode portion can be reduced, the size of the island electrode itself can be reduced, and therefore the overall size of the sensor element can be reduced. it can. As a result, since the number of sensor elements per wafer can be increased, an effect that the manufacturing cost can be effectively reduced is also obtained.

  INDUSTRIAL APPLICABILITY The present invention relates to a vehicle sensor and sensor module manufacturing industry that applies MEMS technology, such as a pressure sensor, an angular velocity sensor, an acceleration sensor, an acceleration / acceleration sensor, and a composite sensor thereof, or a sensor manufacturing industry for portable information processing equipment. Can be used widely.

The whole sensor mounting structure sectional view. The 1st sensor element mounting structure top view. The 2nd sensor element mounting structure top view. FIG. Surface drawer mounting structure sectional drawing. An example of a defect structure on the wafer surface. Sensor element mounting structure with bonding members. First effect of high-temperature, high-load multi-stage joining. Second effect of high-temperature, high-load multi-stage joining.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sensor element 2 Integrated circuit 3 Intermediate wiring 4 External connection terminal 5 Exterior package 11 Sensor 11a Angular velocity sensor 11b Acceleration sensor 12 Sensor board 13 Sealing cap 14 Joining frame 15 Groove 16 Pressure vessel 19 Wire extraction electrode 111 Island electrode part 112 Vibration part 113 Polycrystalline silicon thin film

Claims (3)

Each of the angular velocity sensor and the acceleration sensor is sealed in the pressure vessel with different gas pressures, and there is a groove connecting from the inside of the pressure vessel to the outside at the joint interface with the sealing cap on the one sensor substrate side. A sensor device embedded without using a joining member for joining the sensor substrate and the sealing cap by deformation and flow of a stop cap material. In claim 1,
The sealing cap material is a glass containing ionized molecules having a certain movement ability under a temperature near the softening temperature and under an electric field application condition, and the sealing cap material is deformed and flowed by the deformation and flow. A sensor device in which a groove is embedded. Manufacture of a sensor device in which an angular velocity sensor and an acceleration sensor are sealed in a pressure vessel with different gas pressures, and have a groove embedded with a sealing cap material at a bonding interface with a sealing cap on one sensor substrate side A method,
Sealing and bonding the other sensor pressure vessel without embedding the groove;
Thereafter, sealing and joining the one sensor pressure vessel while embedding the groove;
Tona is,
The step of sealing and joining the one sensor pressure vessel while embedding the groove,
Joining in a multi-step process including the step of applying an electric field and anodic bonding while pressing against the sensor substrate with a load sufficient to deform and flow the sealing cap material near the softening temperature of the sealing cap material. A method for manufacturing a sensor device.

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