JP2010139314A - Semiconductor stress sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor stress sensor having a small structure and capable of simultaneously detecting a plurality of stresses. <P>SOLUTION: The semiconductor stress sensor is formed by stacking a first stress detection wafer part 1 detecting a pressure, a second stress detection wafer part 2 detecting acceleration, and a through-wiring wafer part 3 in a vertical direction. Lead-out wiring 24a outputting an electric signal according to the pressure detected by the first stress detection wafer part 1 to the outside of the sensor is formed at the second stress detection wafer part 2. Lead-out wiring 24b connected to the lead-out wiring 24a and outputting an electric signal corresponding to the pressure detected by the first stress detection wafer part 1 to the outside of the sensor and lead out wiring 31 outputting an electric signal corresponding to the acceleration detected by the second stress detection wafer part 2 to the outside of the sensor are formed at the through-wiring wafer part 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor stress sensor that detects a plurality of physical quantities (stresses) with one sensor.

Conventionally, as a sensor technology for detecting stress such as pressure and acceleration, for example, those described in the following documents are known (see Patent Document 1). This document describes an invention in which a triaxial acceleration sensor is formed which is joined and integrated between a base plate and a cover plate to simultaneously detect accelerations in the X, Y, and Z3 directions perpendicular to each other.
JP-A-7-273353

  The conventional stress sensor can detect only one type of stress such as acceleration. For this reason, when used for multifunctional devices such as mobile information devices such as mobile phones and digital cameras that require detection of multiple stresses such as acceleration and pressure, the acceleration for detecting the acceleration It was necessary to form the stress sensor by arranging the sensor part and the pressure sensor part for detecting pressure side by side with respect to the semiconductor base.

  In such a structure, there has been a limit to downsizing the sensor and integrating it with other semiconductor devices, which has been an obstacle when mounted on a small device such as a portable device.

  The present invention has been made in view of the above, and an object of the present invention is to provide a semiconductor stress sensor having a small configuration and capable of detecting a plurality of different stresses.

  In order to achieve the above object, a semiconductor stress sensor according to the present invention includes a first stress detection wafer unit that detects a first stress, a second stress detection wafer unit that detects a second stress, A wiring formed with a first lead-out wiring that outputs a detection signal detected by the first stress detection wafer unit and a second lead-out wiring that outputs a detection signal detected by the second stress detection wafer unit A first feature is that the first stress detection wafer portion, the second stress detection wafer portion, and the wiring wafer portion are stacked and arranged.

  Moreover, the semiconductor stress sensor according to the present invention suppresses the displacement of the first stress detection wafer unit that detects the first stress and the detection unit that detects the second stress and detects the first stress. And a second stress detection wafer portion on which lead-out wiring for outputting a detection signal detected by the first stress detection wafer portion is formed, and the first stress detection wafer A second feature is that the second stress detection wafer portion is laminated.

  The semiconductor stress sensor according to the present invention is the semiconductor stress sensor according to the first feature or the second feature, wherein the first stress detection wafer unit detects acceleration or pressure as the first stress, and the second stress is detected. The third feature of the stress detection wafer portion is to detect pressure or acceleration as the second stress.

  The semiconductor stress sensor having the first feature according to the present invention can be downsized by arranging a plurality of sensors for detecting different stresses in a stacked manner in the vertical direction.

  In the semiconductor stress sensor of the second feature according to the present invention, the suppression unit is arranged and formed on the first stress detection wafer unit, thereby suppressing the displacement of the detection unit that detects the first stress by the suppression unit. It becomes possible.

  In the semiconductor stress sensor of the third feature according to the present invention, it is possible to reduce the size of the sensor that detects stresses having different acceleration and pressure.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best embodiment for carrying out the present invention will be described below with reference to the drawings.

  1 is a cross-sectional view showing a configuration of a semiconductor stress sensor according to Embodiment 1 of the present invention, and FIG. 2 is a front view thereof. The semiconductor stress sensor of Example 1 shown in FIG. 1 and FIG. 2 includes a first stress detection wafer unit 1 that detects a first stress, a second stress detection wafer unit 2 that detects a second stress, A through-wiring wafer portion 3 is provided, and the first stress detection wafer portion 1 and the through-wiring wafer portion 3 are laminated and formed with the second stress detection wafer portion 2 interposed therebetween.

  The first stress detection wafer unit 1 has a function of a pressure sensor that detects pressure as the first stress, and FIG. 3 is a front view thereof. The first stress detection wafer portion 1 is formed with a diaphragm portion 12 that becomes a pressure receiving portion by thinning the center of a rectangular frame portion 11. When pressure is received from the lower surface (surface not joined to the second stress detection wafer part 2) side of the first stress detection wafer part 1, the diaphragm part 12 is displaced in the vertical direction according to the physical quantity of this pressure, This displacement is detected as, for example, the amount of change in the resistance value of a piezoresistor (not shown) formed on the upper surface of the diaphragm portion 12 (the surface on the side where the second stress detection wafer portion 2 is bonded). The pressure applied to the first stress detection wafer unit 1 is detected by taking out the amount of change in value as an electrical signal outside the sensor.

In the first stress detection wafer unit 1, an electrode pad unit 13 for taking out an electric signal to the outside is disposed on the surface of the frame unit 11 on the side to which the second stress detection wafer unit 2 is bonded.
The second stress detection wafer unit 2 has a function of an acceleration sensor that detects acceleration as the second stress, and FIG. 4 is a front view thereof. The second stress detection wafer unit 2 includes a weight unit 23 that is bonded to and supported by four beam units (sensor units) 22 arranged in a cross shape at the center of a rectangular frame unit 21. Yes. When an acceleration is applied to the second stress detection wafer unit 2, the weight unit 23 is displaced according to a physical quantity of the applied acceleration, and the displacement is transmitted to the beam unit 22 to distort the beam unit 22. For example, the strain is detected as a change amount of a resistance value of a piezoresistor (not shown) formed on the surface of the beam portion 22, and the change amount of the resistance value is taken out as an electric signal to the outside of the sensor. The acceleration applied to the detection wafer unit 2 is detected.

  The second stress detection wafer unit 2 has a beam unit 22 bonded to the frame unit 11 of the second stress detection wafer unit 2 and is stacked on the first stress detection wafer unit 1.

  The second stress detection wafer portion 2 is formed with a lead-out wiring 24 a penetrating the frame portion 21 and the beam portion 22 in the peripheral portion thereof. One end of the lead wire 24a is electrically joined to the electrode pad portion 13 of the first stress detection wafer portion 1, and the other end is the surface of the frame portion 21 in the second stress detection wafer portion 2 (through wiring wafer). Part of the wiring that is electrically bonded to the electrode pad portion 25 disposed and formed on the surface to which the portion 3 is bonded and outputs the electrical signal obtained by the first stress detection wafer portion 1 to the outside of the sensor Configure.

  The through wiring wafer portion 3 is formed by being joined to the frame portion 21 of the second stress detection wafer portion 2 and stacked on the second stress detection wafer portion 2, and is formed on the lead wiring 31 and the previous lead wiring 24a. A lead wire 24b to be connected is formed through the wafer.

  One end of the lead-out wiring 31 is electrically bonded to a corresponding electrode pad portion 32 formed on the surface of the through wiring wafer portion 3, and the other end is disposed and formed on the surface of the second stress detection wafer portion 2. In addition, it is electrically bonded to the corresponding electrode pad portion 26, and the previous electrical signal obtained by the second stress detection wafer portion 2 is output to the outside of the sensor.

  The lead wire 24b is electrically bonded to a corresponding electrode pad portion 33 formed on the surface of the through wiring wafer portion 3 at one end, and an electrode pad formed at the second stress detection wafer portion 2 at the other end. Is connected to the lead wire 24a formed on the second stress detection wafer portion 2, and the previous electrical signal obtained by the first stress detection wafer portion 1 is connected to the outside of the sensor. Output.

  Such a laminated structure is formed by bonding the respective wafers using a conventionally known wafer direct bonding technique for directly bonding, for example, silicon wafers of semiconductors constituting each wafer portion. In that case, each electrode pad part of each wafer part is joined using the metal joining technique which joins the metal which comprises the electrode pad part after alignment, for example, gold | metal | money (Au) directly. After the wafers are bonded, the wafers are diced into individual semiconductor stress sensors.

  Such a laminated structure can be easily manufactured by using a WLP (wafer level package) mounting technique that enables formation of wiring and electrodes and resin sealing in the wafer state. Is possible.

  In this way, by integrating two stress sensors, which are different in physical quantity (stress) to be detected, of the acceleration sensor and the pressure sensor by stacking and integrating in the vertical direction with respect to the wafer surface, a semiconductor wafer as in the conventional case Compared to the case where two sensors are arranged in parallel in the horizontal direction, the sensor area can be greatly reduced. Further, since the thickness of each sensor itself is reduced, the thickness in the vertical direction is not so thick as compared with the configuration in which the sensors are arranged in parallel. As a result, the semiconductor stress sensor that detects a plurality of physical quantities can be reduced in size compared to the conventional one, and a sensor suitable for mounting a small device such as a portable device can be provided. Further, by stacking and arranging two sensors on a single wafer, it is possible to increase the degree of integration as compared to the case of arranging them in parallel.

  In the first embodiment, the first stress detection wafer unit 1 is a pressure sensor and the second stress detection wafer unit 2 is an acceleration sensor. However, the first stress detection wafer unit 1 is an acceleration sensor. The two stress detection wafer portions 2 may be configured as a pressure sensor. That is, in FIG. 1, the first stress detection wafer unit functioning as a pressure sensor having the structure shown in FIG. 1 by exchanging the upper and lower lamination positions of the first stress detection wafer unit 1 and the second stress detection wafer unit 2. A second stress detection wafer portion 2 and a through wiring wafer portion 3 that function as an acceleration sensor having the structure shown in FIG.

  Even in such a configuration, the same effect can be obtained, and the acceleration sensor that configures the second stress detection wafer unit 2 with the diaphragm unit 12 of the pressure sensor that configures the first stress detection wafer unit 1. It is possible to suppress the fluctuation of the weight portion 23. Further, since the beam part 22 of the acceleration sensor constituting the second stress detection wafer part 2 is joined to the frame part 11 of the pressure sensor constituting the first stress detection wafer part 1, the diaphragm part 12 of the pressure sensor The lower part can be made airtight, and the pressure sensor can detect a change in absolute pressure.

  FIG. 5 is a sectional view showing a configuration of a semiconductor stress sensor according to the second embodiment of the present invention, and FIG. 6 is a front view. A feature of the second embodiment shown in FIGS. 1 and 2 is that the stop glass 41 is die-bonded in place of the through wiring wafer portion 3 shown in FIG. 1 as compared with the configuration of the first embodiment shown in FIG. In other words, the second stress detection wafer portion 2 is bonded and disposed via a die bond portion 42 formed by a method.

  The electrical signal obtained by the pressure sensor of the first stress detection wafer unit 1 is output to the outside of the sensor by the lead-out wiring 24a formed through the second stress detection wafer unit 2 as in the first embodiment. The electric signal obtained by the acceleration sensor of the second stress detection wafer unit 2 is output to the outside of the sensor from an electrode pad unit formed on the surface of the second stress detection wafer unit 2 although not shown. .

  In such a configuration, it is possible to obtain the same effect as in the first embodiment, and the stop glass 41 is displaced upward in the weight portion 23 where the second stress detection wafer portion 2 detects acceleration. This stop glass 41 can suppress displacement of the second stress detection wafer portion 2 in the upper side (stop glass 41 side) direction of the weight portion 23.

It is sectional drawing which shows the structure of the semiconductor stress sensor which concerns on Example 1 of this invention. It is a front view which shows the structure of the semiconductor stress sensor which concerns on Example 1 of this invention. It is a front view which shows the structure of the 1st stress detection wafer part 1 in the semiconductor stress sensor which concerns on Example 1 of this invention. It is a front view which shows the structure of the 2nd stress detection wafer part 2 in the semiconductor stress sensor which concerns on Example 1 of this invention. It is sectional drawing which shows the structure of the semiconductor stress sensor which concerns on Example 2 of this invention. It is a front view which shows the structure of the semiconductor stress sensor which concerns on Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... 1st stress detection wafer part 2 ... 2nd stress detection wafer part 3 ... Through-wiring wafer part 11, 21 ... Frame part 12 ... Diaphragm part 13, 25, 26, 32, 33 ... Electrode pad part 22 ... Beam Part 23: Weight part 24a, 24b, 31 ... Lead-out wiring 41 ... Stop glass 42 ... Die bond part

Claims (3)

A first stress detection wafer portion for detecting a first stress;
A second stress detection wafer portion for detecting a second stress;
A first lead-out wiring that outputs a detection signal detected by the first stress detection wafer portion and a second lead-out wiring that outputs a detection signal detected by the second stress detection wafer portion are formed. A wiring wafer portion,
A semiconductor stress sensor, wherein the first stress detection wafer portion, the second stress detection wafer portion, and the wiring wafer portion are stacked. A first stress detection wafer portion for detecting a first stress;
A lead-out wiring that detects the second stress and suppresses the displacement of the detection unit that detects the second stress is stacked on the upper part and outputs a detection signal detected by the first stress detection wafer unit And a second stress detection wafer part formed with
A semiconductor stress sensor, wherein the first stress detection wafer part and the second stress detection wafer part are stacked. The first stress detection wafer unit detects acceleration or pressure as the first stress,
The semiconductor stress sensor according to claim 1, wherein the second stress detection wafer unit detects pressure or acceleration as the second stress.

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