JP2006261469A - Micro-electronic-machine device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit the generation of another-axis sensibility by a mounting inclination, and to improve the accuracy of a sensor and a reliability on a joining by enhancing the accuracy of the posture of the sensor, in a packaged micro-electronic-machine device simultaneously extracting and fixing a signal by a conductor bump to a substrate. <P>SOLUTION: The micro-electronic-machine device has bump-joining sections 11 sealing a sensor chip 3 and an upper glass 4 with a pedestal glass 4 and being bump-joined with the pedestal glass 4, through-holes 6 introducing a sensor output from the sensor chip 3 to the bump joining sections 11, and legs 9a and 9b joined with a substrate 5 apart from the conductor bumps 8. The dispersion of the thicknesses of the bumps is suppressed by joining the bump joining sections 11 and the substrate 5 with the conductor bumps 8, the parallelism of the sensor chip 3 and the substrate 5 is ensured, and the balance of a thermal stress is improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a microelectromechanical device such as a physical sensor such as an acceleration sensor or a gyro sensor that senses a physical mechanical quantity.

  2. Description of the Related Art Conventionally, there is an acceleration sensor that is mounted on an automobile or the like as a microelectromechanical device such as a physical quantity sensor and used for motion control of various vehicles. Generally, an acceleration sensor is provided to face a weight part and a weight part. Capacitance type that detects the change in capacitance formed between the electrodes and the piezoresistive type that detects mechanical distortion applied to the flexure as piezoresistance, etc. Semiconductor sensors and the like are known.

  Such a semiconductor sensor is formed as a microelectromechanical device in which a sensor chip formed by microfabrication of a silicon semiconductor substrate is sealed by a package covered with a glass substrate or the like from above and below. And the output of such a micro electro mechanical device is taken out from the printed circuit board mounted by a conductor bump etc. The extracted sensor signal is coupled from a printed circuit board to a semiconductor integrated circuit (ASIC) and subjected to capacitance-voltage conversion or resistance-voltage conversion, and the magnitude of acceleration is measured as an electric signal. And in such a micro electro mechanical device in a physical sensor, since the measurement physical quantity is very small, it is easily influenced by the characteristic especially by the joint inclination of a sensor chip and a board | substrate.

  Therefore, in such a microelectromechanical device, the detection output is greatly influenced by the mounting orientation of the device when the device is mounted on the board. For this reason, in bump bonding using a conductor bump, in which bump height variation is likely to occur, if the thickness (or height) of the bump on the mounting surface differs depending on the location, the attitude accuracy of the sensor tends to deteriorate. At the same time, the variation in the height of the bumps has a problem that the thermal stress balance with respect to the microelectromechanical device is deteriorated and the characteristics of the bonding reliability are deteriorated.

  Hereinafter, an example of a conventional microelectromechanical device will be described with reference to FIG. FIG. 9A shows a cross section of a micro electro mechanical device, and FIG. 9B shows a back surface of the device to be bump-bonded.

  In these drawings, a microelectromechanical device 100 includes a sensor chip 102 formed on a silicon semiconductor substrate, and an upper glass portion 101 and a pedestal glass portion 103 that cover and seal the sensor chip 102 from above and below. Yes. The sensor chip 102 is provided with a sensor structure 107 that detects a change in capacitance or resistance by providing a movable part that can move according to a physical quantity such as acceleration, and the sensor output is output from an internal wiring provided in the pedestal glass part 103. It is taken out from the substrate 105 to be bump-bonded through the through hole 104.

  In the above conventional example, the microelectromechanical device 100 and the printed circuit board 105 are joined by conductor bumps. However, at the time of this bump bonding, the thickness of the conductor bump to which the solder or the like is dissolved is not necessarily uniform due to the nature of the dissolved liquid, and there is a considerable difference in thickness. Therefore, the parallelism between the sensor chip 102 and the printed circuit board 105 is deteriorated, and there is a possibility that the attitude accuracy of the sensor that needs to detect a minute physical quantity is deteriorated. In addition, there is a problem that the thermal stress balance is deteriorated due to variations in the height of the bumps after bonding, leading to deterioration in characteristics of bonding reliability.

  As another conventional example, for example, as shown in Patent Document 1, an elastic conductive adhesive bump is formed on a metal bump of a bare chip, and the bare chip is pressed onto an electrode of a substrate to form an elastic conductive adhesive. A temporary fixing agent formed of a resin is supplied between positions that do not contact the bumps, for example, between the metal bumps in the center of the bare chip, the bare chip is pressed against the substrate in a heated state, and the temporary fixing agent is cured. A sensor module that is temporarily fixed to a substrate has been proposed.

However, the temporary fixing agent provided between the metal bumps is a temporary fixing member for operation confirmation and the like provided in the manufacturing process, and is made of a resin material and accompanied by temperature deformation. The parallelism is not sufficiently maintained. Therefore, similar to the conventional example, there is a problem that the posture accuracy may be deteriorated and the thermal stress balance is deteriorated due to variation in bump height.
Japanese Patent Laid-Open No. 2004-165414

  The present invention has been made to solve the above problem, and by suppressing variations in bump height, it is possible to ensure parallelism to the substrate, and to suppress the occurrence of other-axis sensitivity due to mounting tilt. An object of the present invention is to provide a microelectromechanical device that can improve the sensor accuracy by improving the posture accuracy of the sensor, improve the thermal stress balance, and improve the characteristics of bonding reliability.

  In order to achieve the above object, a first aspect of the present invention is a packaged micro electromechanical device that simultaneously extracts and fixes a signal by a conductor bump to a substrate, and is bonded to the substrate separately from the bump bonding portion. At least one leg portion is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the bump bonding portion is disposed outside the leg portion.

  According to a third aspect of the present invention, in the first aspect of the present invention, the layer provided with the leg portion is formed by connecting another leg portion to the layer connecting the conductive bump.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, a bump dent for conductor bump bonding is provided, and the bump dent has a tapered surface.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a cavity is provided around the bump dent to allow the melted bumps to escape when the conductor bumps are joined.

  The invention of claim 6 is the invention according to claim 4 or claim 5, wherein the tapered surface of the bump recess is formed by anisotropic etching.

  The invention according to claim 7 is the invention according to claim 4 or 5, wherein the tapered surface of the bump recess is formed by blasting.

  According to the first aspect of the present invention, variation in bump height can be reduced. Accordingly, parallelism with respect to the substrate can be ensured, and the occurrence of other-axis sensitivity due to mounting tilt can be suppressed, so that the sensor accuracy can be improved by increasing the posture accuracy of the sensor. Further, since the thermal stress balance can be improved, the thermal stress can be stabilized and high bonding reliability can be obtained.

  According to the invention of claim 2, since the bump bonding portion is moved away from the central portion of the micro electro mechanical device, it is difficult to propagate the thermal stress propagating from the bump bonding portion to the central portion of the device in which the sensor chip or the like is present. Reliability can be ensured.

  According to the invention of claim 3, since the legs can be accurately formed and joined to the plane of the microelectromechanical device with different parts, the legs are processed with a counterbore and the like and three-dimensionally formed on the back surface of the device. The variation in the thickness of the leg portion can be reduced as compared with the formation of unevenness. As a result, variations in solder thickness can be reduced, and the bonding reliability can be improved.

  According to the invention of claim 4, the bonding area of the conductor bump can be increased. Thereby, joining reliability can be made still higher.

  According to the fifth aspect of the present invention, the melted bumps can escape into the cavities at the time of bump bonding. As a result, the device does not float from the substrate, variation in the height of the bump after melting can be reduced, and high bonding reliability stable in terms of thermal stress can be obtained.

  According to the invention of claim 6, the tapered portion can be formed with high accuracy by forming the tapered surface of the bump recess by anisotropic etching. Thereby, the variation in the thickness of the bump can be suppressed and the bonding reliability can be improved.

  According to the invention of claim 7, since the taper surface can be formed rough, the surface area of the taper surface can be increased, and the bonding area of the conductor bump can be increased, and the bonding reliability can be further improved.

  A microelectromechanical device (hereinafter simply referred to as a device) according to a first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a cross section of the device according to the present embodiment, and FIG. 2 shows a plane of the back surface of the device. In each figure, corresponding members are denoted by the same reference numerals.

  The device 1 includes a sensor chip 3 formed on a silicon semiconductor substrate, and an upper glass part 4 and a pedestal glass part 4 that cover the sensor chip 3 from above and below and seal the package. The sensor chip 3 includes a structure 7 having a sensor detection function that is formed by semiconductor microfabrication and detects a capacitance and an electrical resistance that change according to physical quantities. The structure 7 detects a physical quantity such as acceleration and outputs a sensor detection signal from the sensor chip 3. The pedestal glass portion 4 includes a through hole 6 through which a sensor detection signal from the sensor chip 3 passes, and a bump bonding portion 11 provided on the back surface 10 of the pedestal glass portion 4 to be bonded to the conductor bump 8 at one end of the through hole 6. In addition to the bump bonding portion 11, two leg portions 9 a and 9 b to be bonded to the substrate 5 are provided. Further, a space 12 is provided on the joint surface of the pedestal glass portion 4 with the sensor chip 3 so that the structure 7 of the sensor chip 3 does not contact the pedestal glass portion 4 with a normal physical quantity. The material of the conductor bump 8 is, for example, solder, gold, silver paste or the like.

  In the device 1 configured as described above, the sensor detection signal detected by the sensor chip 3 is guided to the bump bonding portion 11 through the through hole 6. When the device 1 is pressed against the substrate 5 at a high temperature and heated while sandwiching the conductor bump 8 (for example, solder), the solder is melted and the device 1 and the substrate 5 are soldered. At this time, the distance between the device 1 and the substrate 5 is defined by the height of the leg portions 9a and 9b by the two leg portions 9a and 9b provided in the device 1, so that both can be kept parallel. That is, by performing the height positioning with the legs 9a and 9b, the variation in the height of the bumps is reduced. Thereby, the parallelism between the sensor chip 3 and the substrate 5 of the device 1 is maintained, the occurrence of other-axis sensitivity of the sensor due to the mounting inclination is suppressed, and the accuracy of the sensor can be improved. At the same time, due to the parallelism, heat is transmitted uniformly, uniform stability in terms of thermal stress can be obtained, and bonding reliability can be improved.

  Next, a device according to a second embodiment of the present invention will be described with reference to FIG. FIG. 3 shows a plan view of the back surface of the device according to the present embodiment. This embodiment is different from the above-described embodiment in that it includes four leg portions that are bonded to the substrate separately from the bump bonding portion.

  In the figure, the pedestal glass part 4 is provided with legs 9c to 9f at four corners, so that the parallelism between the device 1 and the substrate 5 can be maintained and the bonding position range of the bumps can be widened. The degree of freedom in designing the position of the bump bonding portion 11 is increased, and the pattern wiring for bonding the substrate 5 can be easily designed.

  Next, a device according to a third embodiment of the present invention will be described with reference to FIG. FIG. 4A shows a cross section of the device 1 according to the present embodiment, and FIG. 4B shows a plane of the back surface of the device 1. This device 1 is different from the above-described embodiment in that a leg portion 13 is provided on the center side of the pedestal glass portion 4 and a conductor bump 8 and a bump joint portion 11 are provided outside the leg portion 13.

  In this device 1, the surface of the pedestal glass portion 4 that contacts the sensor chip 3 and the bottom surface of the leg portion 13 of the pedestal glass portion 4 are formed in parallel. Therefore, when the bump bonding portion 11 and the substrate 5 are bonded by the conductor bumps 8, the pedestal glass portion 4 and the substrate 5 are bonded without being inclined by pressing and bonding the leg portions 13 to the substrate 5. Further, an inclined surface 14 is provided on the side surface of the leg portion 13 on the side of the conductor bump 8 to widen the range in which the bump flows during bonding.

  With the configuration described above, the parallelism between the sensor chip 3 and the substrate 5 is maintained, the sensor's other axis sensitivity due to the mounting tilt is suppressed, and the accuracy of the sensor is improved. Further, since the bump bonding portion 11 is arranged outside the leg portion 13, the position of the bump bonding portion 11 is moved away from the structure 7 of the sensor chip 3, so that the thermal stress propagated from the bump bonding portion 11 reaches the structure 7. It becomes difficult to propagate. Thereby, generation | occurrence | production of the distortion in the structure 7 by a thermal stress can be prevented, and joining reliability can further be improved.

  Next, a device according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 5 shows a cross section of the device 1. This device 1 is different from the above embodiment in that legs formed on the pedestal glass portion 4 are formed separately from the pedestal glass portion 4 and joined to the pedestal glass portion 4.

  In this device 1, the leg portion is not formed on the pedestal glass portion 4 itself, but an inverted trapezoidal leg pedestal 15 is separately formed of glass or ceramic material, and the leg pedestal 15 is the pedestal glass portion 4. The leg part of the base glass part 4 is comprised by joining to the back surface.

  With the above configuration, the device 1 can use, as the leg, the leg base 15 that is accurately formed of a member different from the pedestal glass part 4. Less. Therefore, it is not necessary to process the back surface of the pedestal glass portion 4 with spot facings to form the three-dimensional unevenness in order to form the leg portion, and the joining reliability can be improved. Moreover, if the leg base 15 is comprised with a metal member etc., the heat dissipation effect of the device to be joined can be enhanced.

  Next, a device according to a fifth embodiment of the present invention will be described with reference to FIG. FIGS. 6A and 6B show the cross section and the back surface of the device 1 before bump bonding, and FIGS. 6C and 6D show the cross section and the back surface of the device 1 after bump bonding. This device 1 is different from the above-described embodiment in that bump bumps 16 for conductor bump bonding are provided in the bump bonding portions 11 on the back surface 10 of the pedestal glass portion 4 and the bump depressions 16 have a tapered surface 16a.

  In this device 1, a plurality of bump recesses 16 having a taper surface 16 a serving as a recess or groove for embedding the conductor bump 8 is provided in the bump bonding portion 11 on the back surface 10 of the pedestal glass portion 4. On the surface including the tapered surface 16 a of the bump recess 16, a conductor bump base 17 to be joined to the conductor bump 8 is formed. Thus, by providing the taper surface 16a in the bump recess 16, it is possible to effectively increase the bonding area of the conductor bump 8 with the bump bonding portion 11, so that the bonding reliability is further increased. Can be high.

  Further, a cavity 18 is provided around the bump recess 16 for releasing the melted bump when the conductor bump 8 is joined. The cavity 18 allows the melted bump to escape to the periphery, so that the bump does not rise. As a result, the base glass portion 4 can be prevented from floating with respect to the substrate 5 at the time of bonding, so that variations in bump height can be reduced, mounting inclination can be prevented, sensor accuracy can be improved, and thermal stress can be equalized. The stability of the device can be improved.

  Next, a device according to a sixth embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a cross section of the device 1. This device 1 differs from the above embodiment in that the tapered surface 16a of the bump recess 16 is formed by anisotropic etching.

  In this device 1, the taper surface 16a of the bump recess 16 is formed by anisotropic etching with good linearity such as dry etching using high-speed ions in plasma. Therefore, the tapered surface 16a can be formed with high accuracy. Thereby, the amount of the conductor bumps 8 in the bump recess 16 can be made constant, and variations thereof can be suppressed.

  Next, a device according to a seventh embodiment of the present invention will be described with reference to FIG. FIG. 8A shows a cross section of the device 1, and FIG. 8B shows an enlarged view of a portion A surrounded by a dotted line in FIG. This device 1 differs from the above embodiment in that the tapered surface 16a of the bump recess 16 is formed by blasting.

  By forming the taper surface 16a by blasting, the taper surface 16a is roughened and can be formed roughly like the taper surface 16b. Therefore, the coupling area between the conductor bump 8 and the taper surface 16b is increased, and the bonding reliability is increased. Can be increased.

  As described above, according to the device 1 according to the present embodiment, variation in bump height can be reduced, and parallelism with respect to the substrate 5 can be ensured. Thereby, it is possible to suppress the occurrence of other-axis sensitivity due to the mounting inclination, and it is possible to improve the sensor accuracy by increasing the posture accuracy of the sensor. At the same time, the thermal stress balance can be improved and the characteristics of bonding reliability can be improved.

  In addition, this invention is not restricted to the said embodiment, Various deformation | transformation are possible. For example, by providing the bump bonding portion outside the leg portion, the thermal stress propagating from the bump bonding portion can be made difficult to propagate to the structure by keeping the bump bonding portion away from the sensor chip structure. Bonding reliability can be ensured.

  In addition, by forming the leg part formed on the pedestal glass part 4 separately from the pedestal glass part 4 to form the leg base, the leg part is processed with a counterbore, etc., and three-dimensional unevenness is provided. Rather than being formed, the leg base formed with different parts with high precision is joined to the back surface of the pedestal glass part 4 to form a leg part, thereby reducing variations in the thickness of the leg part. Variation in the thickness of the metal can be reduced, and the bonding reliability can be improved. Furthermore, if this leg base is made of a metal member, the heat dissipation effect of the devices to be joined can be enhanced.

  Further, by providing a taper surface in the bump depression of the bump bonding portion, the bonding area of the conductor bumps increases, so that the bonding reliability can be further increased.

  In addition, by providing a cavity around the bump recess to release the bumps that were melted when the conductor bumps were joined, the sensor can be prevented from floating from the substrate due to the melted bumps when the bumps were joined. Variations in thickness can be reduced. Accordingly, it is possible to obtain high bonding reliability that is stable in terms of thermal stress.

  Further, the tapered portion can be formed with high accuracy by forming the tapered surface of the bump recess by anisotropic etching. Thereby, the variation in the thickness of the bump can be reduced, and the bonding reliability can be improved.

  Furthermore, by forming the taper surface of the bump recess by blasting, the taper surface can be roughened, so that the effective surface area of the taper surface can be increased, the bonding area of the conductor bump is increased, and the bonding reliability is increased. Can be further improved.

1 is a cross-sectional view of a micro electro mechanical device according to a first embodiment of the present invention. The back view of the said device. The back view of the microelectromechanical device which concerns on the 2nd Embodiment of this invention. (A) is sectional drawing of the microelectromechanical device which concerns on the 3rd Embodiment of this invention, (b) is a top view of the back surface of the device. Sectional drawing of the micro electro mechanical device which concerns on the 4th Embodiment of this invention. (A), (b) is sectional drawing and back view which show the state before bump joining of the micro electro mechanical device which concerns on the 5th Embodiment of this invention, (c), (d) shows the state after bump joining. Sectional drawing and back view shown. Sectional drawing of the micro electro mechanical device which concerns on the 6th Embodiment of this invention. (A) is sectional drawing of the micro electro mechanical device which concerns on the 7th Embodiment of this invention, (b) is an enlarged view of the A section of (a). (A) is sectional drawing of the conventional microelectromechanical device, (b) is a back view of the device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microelectromechanical device 2 Sensor chip 3 Upper glass part (package)
4 pedestal crows (package)
5 Substrate 8 Conductor bump 9, 13 Leg 15 Leg base (another leg)
11 Bump joint 16 Bump dent 16a, 16b Tapered surface 18 Cavity

Claims (7)

In a packaged microelectromechanical device that simultaneously extracts and fixes a signal by a conductor bump to a substrate,
A micro electro mechanical device comprising at least one or more legs that are bonded to the substrate separately from the bump bonding portion.   The microelectromechanical device according to claim 1, wherein the bump bonding portion is disposed outside the leg portion.   2. The microelectromechanical device according to claim 1, wherein the layer provided with the leg is formed by connecting another leg to the layer connecting the conductor bump.   2. The micro electro mechanical device according to claim 1, wherein a bump recess for bonding a conductor bump is provided, and the bump recess has a tapered surface.   5. The microelectromechanical device according to claim 4, wherein a cavity is provided around the bump recess for releasing a bump dissolved at the time of joining the conductor bump.   6. The microelectromechanical device according to claim 4, wherein the tapered surface of the bump recess is formed by anisotropic etching.   6. The microelectromechanical device according to claim 4, wherein the tapered surface of the bump recess is formed by blasting.

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