JP2006208272A - Semiconductor multiaxial acceleration sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor multiaxial acceleration sensor having a high impact-resistant property. <P>SOLUTION: The semiconductor multiaxial acceleration sensor 1 is equipped with a sensor body 10 being mounted on a bending section 13, and by using a change in resistivity, detecting a displacement of a weight section 12 which is supported by a frame-like section 11 through the bending section 13 at the inside of the frame-like section 11. A first cover 2 which has a recessed section 2a and at least a stopper section 4 opposite to an additional weight section 12a, is disposed on the first surface side of the sensor body 10. Furthermore, a second cover 3 which has a recessed section 3a, is disposed on the rear surface side of the sensor body 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor multi-axis acceleration sensor which is used in, for example, automobiles and home appliances and has sensitivity to accelerations in a plurality of directions.

  An example of a conventional semiconductor multi-axis acceleration sensor includes a sensor main body having a weight portion disposed inside a rectangular frame-shaped frame portion and detecting accelerations in a plurality of directions, for example, three-axis directions.

The above-mentioned semiconductor multi-axis acceleration sensor has a rectangular parallelepiped main weight portion in which the weight portion is supported by the frame portion via four flexure portions, and a rectangular parallelepiped shape that is continuously connected to each of the four corners of the main weight portion. The four additional weight portions are provided. The sensor main body of the semiconductor multi-axis acceleration sensor is formed by electrically connecting a diffusion layer wiring provided in each bending portion and a metal wiring provided on the surface of the main weight portion to a piezoresistor that is a resistor. In this configuration, the diffusion layer wiring and the metal wiring are electrically connected to detect accelerations in a plurality of directions (see, for example, Patent Document 1).
JP 2004-109114 A

  However, in the semiconductor multi-axis acceleration sensor as described above, for example, there is a need to reduce the breakage of the bent portion due to the displacement of the weight portion when applying acceleration in the thickness direction of the sensor body.

  Moreover, in the semiconductor multi-axis acceleration sensor as described above, for example, when excessive acceleration is applied in the thickness direction of the sensor body, the metal wiring provided on the surface of the main weight portion may be destroyed. There was also a need to make it as low as possible.

  The present invention has been made to remedy the above problems, and an object thereof is to provide a semiconductor multi-axis acceleration sensor having high impact resistance strength.

  In order to achieve the above-described object, in the semiconductor multi-axis acceleration sensor according to claim 1 of the present invention, a weight portion disposed inside a frame-like frame portion is extended to the frame portion with the weight portion interposed therebetween. A sensor that is supported by the frame portion via at least one set of bending portions, and a resistor whose resistivity changes due to strain generated in the bending portion due to displacement of the weight portion with respect to the frame portion is formed in each of the bending portions. A metal wiring that includes a main body, includes a diffusion layer wiring in which each of the bent portions is electrically connected to the resistor, and the weight portion electrically connects between the resistors provided on each of the bent portions on the surface And an additional weight connected continuously and integrally with the main weight. The resistor, the diffusion layer wiring, and the metal wiring are electrically connected, and acceleration in a plurality of directions is achieved. Semiconductor multi-axis processing to detect each A first substrate that is electrically insulated and connected to the sensor body on the frame portion on the metal wiring side, and the sensor on the frame portion on the opposite side of the first substrate. A second substrate provided in an electrically insulated connection with the main body, the first substrate further having a recess on the side facing the sensor main body, and the recess includes at least the additional weight portion A stopper portion is provided at the facing portion.

  The semiconductor multi-axis acceleration sensor according to claim 2 of the present invention is the semiconductor multi-axis acceleration sensor according to claim 1, wherein at least a portion facing the additional weight portion is roughened in the stopper portion. ing.

  A semiconductor multi-axis acceleration sensor according to claim 3 of the present invention is the semiconductor multi-axis acceleration sensor according to claim 1 or 2, wherein the stopper portion is formed of a photosensitive organic film.

  In the semiconductor multi-axis acceleration sensor having such a configuration, the first substrate and the second substrate are provided on the front and back surfaces of the sensor body, respectively, so that when acceleration is applied in the thickness direction of the sensor body, The movement range can be regulated to prevent the bending portion from being broken.

  In addition, the semiconductor multi-axis acceleration sensor having such a configuration is provided with a stopper portion on the first substrate, so that when an excessive acceleration is applied in the thickness direction of the sensor body, the additional weight portion contacts the stopper portion. In this way, it is possible to prevent the metal wiring provided on the surface of the main weight portion from coming into contact with the first substrate and being destroyed.

  Embodiments according to the present invention will be described below with reference to the drawings. In addition, in each figure, the structure which attached | subjected the same code | symbol shows that it is the same structure, The description is abbreviate | omitted.

  An embodiment of the present invention will be described with reference to FIGS. 1 is a plan view showing a semiconductor multi-axis acceleration sensor according to an embodiment of the present invention (a plan view seen from an upper surface side defined later), and FIG. 2A is a cross-sectional view taken along line AA in FIG. FIG. 2B is a cross-sectional view taken along the line BB in FIG. FIG. 1 shows a plan view with the first cover 2 removed for easy viewing. FIG. 1A is a simplified plan view omitting surface wiring and the like, and FIG. 1B further shows diffusion layer wiring 15 and metal wiring 16 in FIG. 1A. It is a top view. Moreover, FIG. 2 is sectional drawing in an AA cross section and a BB cross section, and in order to make it easy to see, illustration of the site | part which exists in the back side from these cross sections is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 2, the semiconductor multi-axis acceleration sensor 1 includes a sensor main body 10 formed using an SOI substrate 100 and an anodic bonding to the upper surface (front surface) side in the thickness direction of the sensor main body 10. The glass first cover 2 that is the first substrate provided, and the glass second cover 3 that is the second substrate provided by anodic bonding on the lower surface (back surface) side in the thickness direction of the sensor body 10. This is a configuration provided.

  Here, the vertical (front and back) directions of the semiconductor multi-axis acceleration sensor 1 cannot be uniquely defined because it depends on the orientation in the actual use state, but in the description of the present embodiment, it is shown in FIG. Thus, the vertical direction is defined such that the arrangement side of the first cover 2 is the upper (front) side and the arrangement side of the second cover 3 is the lower (back) side.

  The SOI substrate 100 is a part of a so-called SOI wafer in which a buried oxide film 102 as an insulating film is formed between a support substrate 101 made of a silicon substrate and an n-type silicon layer (silicon active layer) 103. The support substrate 101 is provided on the back surface side of the sensor main body 10, and the silicon layer 103 is provided on the front surface side of the sensor main body 10.

  As shown in FIGS. 1 and 2, the sensor main body 10 includes four flexible portions 13 in which the weight portion 12 disposed inside the rectangular frame-shaped frame portion 11 is thinner than the frame portion 11. 13 has a structure in which the frame portion 11 is continuously and integrally connected through 13.

  The surface of the frame portion 11 is anodically bonded to the first cover 2 over the entire circumference, and the back surface of the frame portion 11 is anodically bonded to the second cover 3 over the entire circumference.

  As shown in FIG. 2, a gap is formed between the surface of the weight portion 12 and the first cover 2 so that the weight portion 12 can be displaced in the thickness direction of the weight portion 12. A gap is formed between the back surface and the second cover 3 to enable the weight portion 12 to be displaced in the thickness direction of the weight portion 12.

  The weight portion 12 is continuous to each of the rectangular parallelepiped main weight portion 12a supported by the frame portion 11 via the four flexure portions 13 and the four corners of the main weight portion 12a when viewed from the main surface side of the sensor body 10. It has four rectangular parallelepiped-shaped additional weight parts 12b connected together. That is, each additional weight portion 12b is disposed in a space surrounded by the frame portion 11 and the main weight portion 12a and two bent portions 13 extending in a direction orthogonal to each other, and around each additional weight portion 12b, A slit 14 is formed except for a connecting portion with the main weight portion 12a.

  Here, the thickness direction of the sensor body 10 is the z-axis direction, and the direction along one side of the rectangular frame-shaped frame portion 11 is the x-axis direction on the plane orthogonal to the z-axis direction, and the direction along the side perpendicular to the one side. Is defined as the y-axis direction, the weight portion 12 is extended in the x-axis direction to sandwich the main weight portion 12a, and a pair of bent portions 13 is extended in the y-axis direction to sandwich the main weight portion 12a. It is supported by the frame portion 11 through a pair of two bent portions 13.

  Each bending portion 13 includes a diffusion layer wiring 15 that is electrically connected to a piezoresistor that is a resistor (not shown).

  The main weight portion 12a serves as a wiring portion that bridge-connects piezoresistors provided in different flexure portions 13. When each wiring intersects, one of the intersecting wirings is appropriately connected to a diffusion layer wiring (not shown). ) And the other is formed by the metal wiring 16 provided on the surface.

  Here, the metal wiring 16 is, for example, an aluminum wiring and is formed on the insulating film 104 on the silicon layer 103 in the main weight portion 12a, and the diffusion layer wiring 15 and the metal wiring 16 are in contact portions (not shown). In the figure). Further, the planar shape of the diffusion layer wiring 15 formed in the main weight portion 12a is, for example, L-shaped although not shown in the figure, and the diffusion layer wirings 15 formed in the main weight portion 12a do not cross each other. It is arranged.

  The frame unit 11 includes a pad electrode (not shown). The diffusion layer wiring 15 is joined to a pad electrode corresponding to an output terminal (not shown) of each diffusion layer wiring.

  The resistor is electrically connected to the diffusion layer wiring 15 and the metal wiring 16, and the acceleration of the bending portion 13 in a plurality of directions (in the present embodiment, the x-axis, y-axis, and z-axis directions) due to the displacement of the weight portion 12. Detect each.

  When the weight portion 12 is displaced in the z-axis direction, the first cover 2 and the second cover 3 restrict the movement range of the weight portion 12 to prevent the bending portion 13 from being broken, and the sensor body 10 is broken. This is provided to prevent this.

  As shown in FIG. 2, each of the first cover 2 and the second cover 3 has a concave portion in order to secure a swinging space (an air gap between the weight portion) of the weight portion 12 on the surface facing the weight portion 12. 2a and a recess 3a. Note that the recess 2a and the recess 3a are formed by etching, sandblasting, or the like.

  Further, the first cover 2 further includes a stopper portion 4 made of, for example, glass at a portion facing the at least four additional weight portions 12b in the above-described recess 2a. In addition, the stopper part 4 is not provided in the recessed part 2a facing the main weight part 12a at least.

  The stopper portion 4 may be formed integrally with the first cover 2, or may be formed separately and integrated later. Note that the surface of the stopper portion 4 facing the additional weight portion 12b is preferably subjected to a roughening process so that the additional weight portion 12b can be easily prevented from joining the stopper portion 4.

  Here, the stopper portion 4 prevents the metal wiring 16 provided on the surface of the main weight portion 12a from coming into contact with the first cover 2 and being broken when an excessive acceleration is applied in the z-axis upward direction, for example. When the weight portion 12 is displaced in the z-axis upward direction, the additional weight portion 12b is formed before the metal wiring 16 provided on the surface of the main weight portion 12a contacts the first cover 2. By making it contact with the stopper part 4, the metal wiring 16 provided in the surface of the main weight part 12a is prevented from contacting the 1st cover 2 and being destroyed.

  For example, the first gap between the metal wiring 16 provided on the surface of the main weight portion 12a and the first cover 2 is about 10 μm, and the second gap between the additional weight portion 12b and the stopper portion 4 is about 5 μm.

  As shown in FIG. 2, the main weight portion 12 a, the frame portion 11, and the bending portion 13 are made of a support substrate 101, a buried oxide film 102, a silicon layer 103, a silicon oxide film stacked on the silicon layer 103, and the like. The insulating film 104 is used.

  The main weight 12 a further includes a metal wiring 16 on the insulating film 104. By forming the additional weight portion 12b with the support substrate 101 and not providing the buried oxide film 102, the silicon layer 103, and the insulating film 104, the second gap can be easily formed. Further, in this case, since the second gap can be made smaller than the first gap as described above, the impact resistance strength of the sensor body 10 can be improved.

  Here, the stopper portion 4 may be formed of a photosensitive organic film that can easily form a patterned protrusion on the first cover 2.

  In the semiconductor multi-axis acceleration sensor 1 according to the present embodiment, by providing the first cover 2 and the second cover 3 on the front and back surfaces of the sensor body 10, acceleration is applied in the z-axis direction that is the thickness direction of the sensor body 10. When done, the movement range of the weight portion 12 in the z-axis direction is restricted to prevent the bending portion 13 from being broken.

  Further, the semiconductor multi-axis acceleration sensor 1 according to the present embodiment is provided with the stopper portion 4 described above on the first cover 2, so that when an excessive acceleration is applied in the z-axis direction, the additional weight portion is the stopper portion. 4 can be prevented from coming into contact with the first cover 2 and being destroyed.

  Here, in the present embodiment, the semiconductor multi-axis acceleration sensor is exemplified as one that detects acceleration in the three-axis direction, but of course, the present invention is not limited to this embodiment as long as it has three or more axes.

1 is a plan view of a semiconductor multi-axis acceleration sensor according to an embodiment of the present invention. It is sectional drawing of the semiconductor multi-axis acceleration sensor which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor multi-axis acceleration sensor 2 1st cover 2a Recessed part 3 2nd cover 3a Recessed part 4 Stopper part 10 Sensor main body 11 Frame part 12 Weight part 12a Main weight part 12b Additional weight part 13 Bending part 14 Slit 15 Diffusion layer wiring 16 Metal wiring DESCRIPTION OF SYMBOLS 100 Substrate 101 Support substrate 102 Buried oxide film 103 Silicon layer 104 Insulating film

Claims (3)

A weight portion disposed inside the frame-shaped frame portion is supported by the frame portion via at least one set of bending portions extending to the frame portion with the weight portion interposed therebetween, and the weight portion of the weight portion with respect to the frame portion is supported. Resistors whose resistivity changes due to strain generated in the flexure due to the displacement are provided with sensor bodies formed in the flexures, and diffusion layer wirings in which the flexures are electrically connected to the resistors. The weight portion comprises a main weight portion provided with metal wiring for electrically connecting the resistors provided on the respective flexure portions on the surface, and an additional weight portion continuously and integrally connected to the main weight portion, A semiconductor multi-axis acceleration sensor for electrically detecting the acceleration in a plurality of directions by electrically connecting the resistor, the diffusion layer wiring, and the metal wiring,
A first substrate provided in an electrically insulated connection with the sensor body on the frame portion on the metal wiring side;
A second substrate provided in an electrically insulated connection with the sensor body on the frame portion opposite to the first substrate,
The first substrate further includes a recess on a side facing the sensor body, and the recess includes a stopper at least at a site facing the additional weight. .   The semiconductor multi-axis acceleration sensor according to claim 1, wherein at least a portion of the stopper portion facing the additional weight portion is roughened.   The semiconductor multi-axis acceleration sensor according to claim 1, wherein the stopper portion is formed of a photosensitive organic film.

Images