KR101633027B1 - Mems sensor - Google Patents

Abstract

Provided is a MEMS sensor capable of suppressing output fluctuation due to thermal hysteresis even when a wiring layer is formed by aluminum.
Gold electrode pads 16a, 16b, 16c, and 16d are formed at four corners of the square MEMS sensor 1. The electrode pads 16a, 16b, 16c and 16d and the detecting element portions 15a, 15b and 15c are connected to each other at the connection wiring layers 20 and 25, respectively. The interconnecting wiring layers 20 and 25 are composed of aluminum lower wiring layers 21 and 26 and gold-colored upper wiring layers 22 and 27. By arranging the lower wiring layers 21 and 26 made of aluminum in an appropriate length in a balanced manner, it is possible to suppress the output fluctuation due to the residual stress due to thermal hysteresis.

Description

[0001] MEMS SENSOR [0002]

The present invention relates to a MEMS sensor having a sensing portion deformed by an external force on a silicon substrate and a sensing element portion detecting the deformation.

Patent Documents 1 and 2 disclose a pressure sensor composed of MEMS (Micro Electro Mechanical Systems). The pressure sensor has a sensor chip formed of silicon. The sensor chip is provided with a diaphragm portion deformed by pressure and a strain gauge detecting strain of the diaphragm portion. The strain gauge is formed by diffusing impurities into the silicon.

In the pressure sensor described in Patent Document 1, the sensor chip is adhered and fixed to the glass pedestal with a silicone adhesive. According to Patent Document 1, it is described that, when the ambient temperature is changed from a low temperature to a high temperature, stress due to thermal hysteresis acts on the sensor chip to cause output fluctuation. To prevent this, the diaphragm portion is surrounded And the influence of the stress on the strain gage provided on the sensor chip is reduced by residual strain of the aluminum film.

Next, in the pressure sensor described in Patent Document 2, a piezo resistor serving as a strain gauge is formed by injecting P-type boron into an N-type silicon substrate. An aluminum film is used as the wiring extending from the piezo resistor, Film, and Ti, Ni, Au, or the like is deposited on the aluminum film only at the portion where the conductive solder is placed.

Japanese Patent Application Laid-Open No. 11-344402 Japanese Patent Application Laid-Open No. 2008-20433

Aluminum has a large hysteresis of residual stress when heat is changed. According to the invention described in Patent Document 1, since the outer periphery of the diaphragm portion is surrounded by the aluminum film, the residual stress generated in the aluminum film formed on the outer periphery is canceled by the residual stress of the aluminum wiring, thereby reducing the output fluctuation caused by thermal hysteresis will be.

However, in the above structure, it is necessary to form a large space for forming the aluminum film on the outer periphery of the diaphragm portion, and it is difficult to reduce the size of the sensor chip.

In the case where the wiring extending from the piezo resistor is formed of an aluminum film as in the pressure sensor described in Patent Document 2, stress remaining in the aluminum film at the time of temperature change acts on the piezo resistor, As shown in Fig.

In order to cope with such a problem, it is also conceivable to form the wiring extending from the piezo resistor (strain gauge) with gold or the like having a small change in the residual stress due to the temperature change. However, since gold has compatibility with silicon, gold is impregnated into the silicon substrate when heat is applied, so that it can not function as a wiring layer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems, and it is an object of the present invention to provide a MEMS device capable of stably forming a wiring layer from a detecting element portion formed on a silicon substrate, and capable of reducing the influence of thermal hysteresis without increasing the product size. And to provide a sensor.

The present invention is a MEMS sensor in which a first substrate and a second substrate, both of which are silicon substrates,

Wherein the first substrate has a space portion and a frame body portion surrounding the space portion, the second substrate has a sensing portion capable of being deformed to be deflected so as to face the space portion, and a sensing portion for sensing the sensing output in accordance with the bending deformation of the sensing portion An element portion is formed,

An insulating layer is formed on a surface of the second substrate, an electrode pad is formed on a surface of the insulating layer, and a connection wiring layer is formed between the electrode pad and the detecting element portion,

Wherein the interconnecting wiring layer comprises a lower wiring layer formed of aluminum which is formed between the second substrate and the insulating layer and connected to the detecting element portion and an upper wiring layer extending from the electrode pad on the surface of the insulating layer, Wherein the upper wiring layer is formed of a conductive metal material having a smaller fluctuation in residual stress due to a temperature change than aluminum and the upper wiring layer and the lower wiring layer are made conductive in an opening provided in the insulating layer.

In the MEMS sensor of the present invention, since the lower wiring layer made of aluminum is formed on the surface of the second substrate which is the silicon substrate, the lower wiring layer can be formed in a stable state. Further, since the interconnecting wiring layer is composed of the lower wiring layer and the upper wiring layer of the conductive metal material having less fluctuation of the residual stress due to the temperature change than aluminum, the thermal hysteresis of the aluminum can be prevented from being excessive, The fluctuation can be suppressed.

In the present invention, it is preferable that the upper wiring layer is formed of gold.

In the present invention, it is preferable that the second substrate is a square, and the electrode pad is located at all corners of the square, and the connection wiring layer is formed in parallel with each side of the square, and the length of the connection wiring layer, And the length of the upper wiring layer is preferably the same in each side of the square.

The wiring pattern of the connection wiring layer is preferably rotationally symmetric with respect to the center of the second substrate at a center of 180 degrees.

In the present invention, by forming the lower wiring layer and the upper wiring layer in the same state on each side of the square, the residual stress of the lower wiring layer made of aluminum can be balanced with each other and the residual stress acting on the detecting element portion Can be reduced.

The MEMS sensor of the present invention is characterized in that the total length of the connecting portion between the lower wiring layer and the detecting element portion and the connecting wiring layer excluding the electrode pad is L0 and the total length of the connecting portion between the upper wiring layer and the lower wiring layer It is preferable that L1 / L0 is 0.46 to 0.88 when the length of the upper wiring layer excluding the electrode pad is L1.

Further, it is preferable that L1 / L0 is 0.76 to 0.88.

The MEMS sensor of the present invention is, for example, a pressure sensor in which a supporting substrate bonded to the second substrate is provided on the side opposite to the second substrate, the space portion is closed, and the sensing portion is deformed to the pressure of the gas .

In the MEMS sensor of the present invention, since the lower wiring layer formed on the second substrate, which is a silicon substrate, is made of aluminum, the lower wiring layer can always be kept in a stable state. Aluminum is characterized in that the residual stress has thermal hysteresis. However, since the connection wiring layer for conducting the detection element portion and the electrode pad is formed of the lower wiring layer made of aluminum and the upper wiring layer made of the conductive metal material such as gold, It is possible to adjust the lower wiring layer to a length dimension in which the influence due to the residual stress is reduced. Therefore, fluctuation of the detection output due to the residual stress of aluminum can be suppressed.

Fig. 1 (A) is a plan view of a MEMS sensor according to an embodiment of the present invention, and Fig. 2 (B) is an explanatory diagram showing a pattern configuration of a detection element part
Fig. 2 is a cross-sectional view taken along line II-II of the MEMS sensor shown in Fig. 1
3 is a sectional view taken along the line III-III of the MEMS sensor shown in FIG. 1
4 is a plan view showing the MEMS sensor of Comparative Example 1
5 is a plan view showing a MEMS sensor of Comparative Example 2
Fig. 6 is a cross-sectional view of the MEMS sensor of Comparative Example 2 shown in Fig. 5 taken along the line VI-VI
7 is a diagram illustrating a variation in output due to thermal hysteresis of a MEMS sensor using aluminum as a wiring layer;
8 is a graph showing a comparison between output fluctuations of the embodiment and the comparative example

The MEMS sensor 1 shown in Figs. 1 to 3 is used as a pressure sensor. The MEMS sensor 1 of the present invention can be configured as a force sensor for detecting a pressing force in addition to the pressure sensor.

2, the MEMS sensor 1 is formed by bonding a support substrate 3 to the lower side of an SOI substrate (Silicon On Insulator wafer) 2. In the SOI substrate 2, the first substrate 11 and the second substrate 12 are bonded to each other with the oxide insulating layer 13 interposed therebetween. The first substrate 11 and the second substrate 12 are silicon (Si) substrates, and the oxide insulating layer 13 is a silicon oxide (SiO ₂ ) layer.

1 (A), the shape of the MEMS sensor 1 when viewed from the top is square, and the first side 1a, the second side 1b, the third side 1c, and the fourth side And a side 1d. The first substrate 11 and the second substrate 12 are also square, and their shapes and dimensions are the same as those of the MEMS sensor 1.

As shown in Fig. 2, the first substrate 11 has a central space portion 11a and a frame portion 11b surrounding the space portion 11a. The space portion 11a is formed so as to penetrate the first substrate 11 up and down. In Fig. 1 (A), the inner wall surface 11c of the space portion 11a is shown by a broken line. The intervals between the first side 1a and the second side 1b and between the third side 1c and the fourth side 1d and the inner wall face 11c are all the same. That is, the width dimension of the frame body portion 11b is uniform on all sides 1a, 1b, 1c and 1d.

The second substrate 12 is a sensing portion (deformation portion or bending portion) 12a that is capable of bending deformation of a portion covering the space portion 11a (a portion facing the space portion 11a), and the frame body portion 11b And the overlapping frame-shaped portion are the wiring portions (wiring regions) 12b.

As shown in FIG. 3, the insulating layer 14 is formed on the surface 12c of the second substrate 12. The insulating layer 14 is composed of a lower insulating layer 14a formed thinly on the surface 12c of the second substrate 12 and an upper insulating layer 14b stacked on the lower insulating layer 14a. The two insulating layers 14a and 14b are inorganic insulating layers. The lower insulating layer 14a is a silicon oxide (SiO ₂ ) layer and the upper insulating layer 14b is a silicon nitride (Si ₂ N ₃ ) layer.

As shown in Fig. 1A, four detector elements 15a, 15b, 15c and 15d are formed on the second substrate 12, respectively. The first detection element part 15a is located away from the first side 1a and the second detection element part 15b is located away from the second side 1b and the third detection element part 15c is located away from the third side 1a, And the fourth detecting element part 15d is located apart from the fourth side 1d.

At least a part of the detecting element portions 15a, 15b, 15c and 15d is formed in the region where the sensing portion 12a is deformed when the sensing portion 12a is deformed. Impurities such as P-type boron are doped on the surface 12c of the second substrate 12 which is an N-type silicon substrate and the detection elements 15a, 15b, 15c and 15d are formed on the surface of the second substrate 12 Is a piezoresistance formed in a part, and this piezoresistance functions as a strain gauge.

The electrode pads 16a, 16b, 16c and 16d are formed on the surface 14c of the insulating layer 14 formed on the surface 12c of the second substrate 12 as shown in Fig. . The electrode pads 16a, 16b, 16c, and 16d are disposed at the corner portions of the square-shaped MEMS sensor 1, respectively. The electrode pads 16a, 16b, 16c and 16d are made of a conductive metal material having a small fluctuation in residual stress due to a temperature change relative to thermal hysteresis and are made of gold (Au), silver (Ag) Copper (Cu) or the like, and is formed of gold in the preferred embodiment described below. The conductive metal material is formed by a sputtering process or the like.

1 (A), between the electrode pad 16a and the first detecting element portion 15a, and between the electrode pad 16a and the third detecting element portion 15c, (Not shown). The gap between the electrode pad 16a and the electrode pad 16c and the second detecting element 15b located diagonally to the electrode pad 16a and the gap between the electrode pad 16c and the fourth detecting element 15d, (Not shown).

The first connection wiring layer 20 is formed on the lower surface of the lower surface of the second substrate 12 between the lower insulating layer 14a and the upper insulating layer 14b as shown in FIGS. The wiring layer 21 and the upper wiring layer 22 formed on the surface 14c of the upper insulating layer 14b. The upper wiring layer 22 is formed integrally with the electrode pad 16a and the electrode pad 16c. That is, when the electrode pad 16a and the electrode pad 16c provided on the diagonal line of the second substrate 12 are paired to form the first electrode pad pair, the electrode pad 16a constituting the first electrode pad pair, And the first connection wiring layer 20 extending from the electrode pad 16c are the same in length and the lengths of the lower wiring layer 21 and the upper wiring layer 22 are the same.

The lower wiring layer 21 is formed on the surface of the lower insulating layer 14a by aluminum. A part of the lower wiring layer 21 is a conductive portion 21a which is in communication with any one of the detecting element portions 15a, 15b, 15c and 15d. 3, an opening is provided in the lower insulating layer 14a in the conductive portion 21a, and a portion of the lower wiring layer 21 in the opening is connected to the detecting element portions 15a, 15b, 15c, 15d. . A part of the upper wiring layer 22 is a conductive portion 22a which is in communication with the lower wiring layer 21. [ 3, an opening is provided in the upper insulating layer 14b in the conductive portion 22a, and the upper wiring layer 22 is in contact with the lower wiring layer 21 at the opening.

The length L0 of the first interconnecting wiring layer 20 in this specification is the length L0 of the lower interconnecting layer 21 and the upper interconnecting layer 22 in the portions excluding the electrode pads 16a and 16c and the conducting portion 21a. Quot; length " The length L1 of the upper wiring layer 22 means a length dimension including the conductive portion 22a excluding the electrode pads 16a and 16c. The lower wiring layer 21 and the upper wiring layer 22 constituting the first connection wiring layer 20 extend in parallel and linearly with the sides 1a, 1b, 1c and 1d of the MEMS sensor 1. [

1 (A), between the electrode pad 16b and the first detecting element portion 15a, and between the electrode pad 16b and the fourth detecting element portion 15d, (25). The gap between the electrode pad 16b and the electrode pad 16d and the second detecting element 15b located on the diagonal side and the gap between the electrode pad 16d and the third detecting element 15c are connected to each other by the second connecting wiring layer 15. [ (25). That is, when the electrode pads 16b and the electrode pads 16d provided on the diagonal line different from the first electrode pad pairs in the second substrate 12 are used as a pair of the second electrode pads, The electrode pad 16b constituting the pair and the second connection wiring layer 25 extending from the electrode pad 16d have the same length and the same ratio of the lengths of the lower wiring layer 26 and the upper wiring layer 27 .

The second connection wiring layer 25 has a lower wiring layer 26 and an upper wiring layer 27. The lower wiring layer 26 is formed on the lower insulating layer 14a in the same manner as the lower wiring layer 21 of the first connection wiring layer 20 so that a part of the lower wiring layer 26 contacts the detecting element portions 15a, 15b, 15c, 15d As shown in Fig. The upper wiring layer 27 is formed integrally with the electrode pads 16b and 16d on the surface 14c of the upper insulating layer 14b in the same manner as the upper wiring layer 22 of the first connection wiring layer 20 , And a part thereof serves as a conduction portion in contact with the lower wiring layer 26 in the partial removal of the upper insulating layer 14b.

The length dimension La of the second connection wiring layer 25 is a length dimension excluding the conductive portions with the detection element portions 15a, 15b, 15c and 15d in the lower wiring layer 26 except for the electrode pads 16b and 16d to be. The length dimension Lb of the upper wiring layer 27 is a length dimension including a conductive portion with the lower wiring layer 26 in the upper wiring layer 27 excluding the electrode pads 16b and 16d. That is, the length dimension La is set to the same reference as L0, and the length dimension Lb is set to the same standard as the length dimension L1.

The second interconnecting wiring layer 25 is formed in a straight line parallel to the sides 1a, 1b, 1c and 1d of the MEMS element 1. However, the length La of the second connection wiring layer 25 is shorter than the length L0 of the first connection wiring layer 20. The ratio of the lengths of the lower interconnect layer 26 and the upper interconnect layer 27 of the second interconnecting wiring layer 25 is set so that the ratio of the lengths of the lower interconnect layer 21 and the upper interconnect layer 22 of the first interconnecting wiring layer 20 The ratio of the length of the lower wiring layer 26 is small. In other words, the ratio of the lengths of the lower wiring layer 21 and the upper wiring layer 22 of the first connection wiring layer 20 is set so that the lengths of the lower wiring layer 26 and the upper wiring layer 27 in the second connection wiring layer 25 The ratio of the length of the lower wiring layer 21 is large.

The patterns of the electrode pads 16a, 16b, 16c and 16d and the patterns of the first connection wiring layer 20 and the second connection wiring layer 25 are the same as those of the center of the MEMS sensor 1 shown in Fig. (Center of gravity) O) centered at 180 degrees. The electrode pads 16a, 16b, 16c and 16d and the first connection wiring layer 20 and the second connection wiring layer 25 are both formed on the wiring portion 12b of the second substrate 12.

As shown in Fig. 2, the supporting substrate 3 is bonded to the lower surface side of the first substrate 11, and the space portion 11a is clogged from the lower side by the supporting substrate 3.

As shown in Fig. 1 (B), in the detecting element portions 15a, 15b, 15c and 15d, the piezo resistance layer is formed in a so-called meander shape, As shown in FIG. Therefore, when the sensing portion 12a of the second substrate 12 is bent downward in Fig. 2, the resistance of the detecting element portions 15a and 15b is increased and the resistance of the detecting element portions 15c and 15d is lowered So that the resistance value of the polarities opposite to each other becomes equal.

As shown in Fig. 1 (A), the four electrode pads 16a, 16b, 16c and 16d connect the detecting element parts 15a, 15b, 15c and 15d so as to constitute a bridge circuit. For example, a power supply voltage is applied to the electrode pad 16a, and the electrode pad 16c is grounded. When the sensing portion 12a is deformed and the sensing element portions 15a, 15b, 15c, and 15d are deformed, the midpoint potentials of the electrode pad 16b and the electrode pad 16d change. Since the midpoint potential of the electrode pad 16b and the midpoint potential of the electrode pad 16d change in opposite polarities, the two midpoint potentials are differentiated, so that the pressure of the gas acting on the sensing portion 12a The detection output can be obtained proportional to the output voltage.

In the MEMS sensor 1 of the embodiment of the present invention shown in Figs. 1 to 3, the first connection wiring layer 20 is composed of the lower wiring layer 21 made of aluminum and the gold wiring upper layer 22, (25) is also formed of a lower wiring layer 26 made of aluminum and a gold upper wiring layer 27

The gold upper wiring layers 22 and 27 are formed on the surface 14c of the upper insulating layer 14b and the gold layer is separated from the second substrate 12 as shown in Fig. 16b, 16c, 16d and the upper wiring layers 22, 27 do not diffuse to the silicon substrate as the second substrate 12 even when the temperature of the upper wiring layers 22, 27 can be maintained in a stable state. On the other hand, the lower wiring layers 21 and 26 formed on the lower insulating layer 14a on the surface of the second substrate 12 are made of aluminum. Since aluminum is difficult to diffuse into the silicon substrate and is maintained in a stable state, The pattern of the lower wiring layers 21 and 26 can be maintained in a stable state.

However, if aluminum remains in a thermal cycle, the stress remains largely fluctuated. If this stress acts directly on the detecting element portions 15a, 15b, 15c and 15d, the fluctuation in the detection output It happens. However, in the MEMS sensor 1 of the embodiment of the present invention shown in Figs. 1 to 3, the first connection wiring layer 20 is composed of the lower wiring layer 21 made of aluminum and the gold wiring upper layer 22, The connection wiring layer 25 is composed of the lower wiring layer 26 made of aluminum and the gold wiring upper wiring layer 27 so that the influence of residual strain on the detecting element portions 15a, 15b, 15c and 15d due to the residual stress of aluminum Can be reduced.

Fig. 7 shows a change in the detection output when the MEMS sensor 1 of the third embodiment described later is placed under a temperature cycle. The abscissa represents the environmental temperature and the ordinate represents the change of the detection output under atmospheric pressure. In Fig. 7, the environmental temperature is raised from 25 캜 to 80 캜 under atmospheric pressure, and then returned to 25 캜. (Pa: Pascal) is the difference between the detection output when the temperature is initially set to 25 ° C and the detection output when the temperature is returned from 80 ° C to 25 ° C. This variation in output is considered to be caused by fluctuation of the residual stress in the MEMS sensor 1 due to thermal hysteresis. In Example 3, which is a preferred example of the embodiment of the present invention, the output fluctuation due to thermal hysteresis is 20 Pa (Pascal) Which is a very small value.

The first reason can be predicted as follows. In the first connection wiring layer 20 and the second connection wiring layer 25, the lower wiring layers 21 and 26 made of aluminum are formed only in a part of the wiring length and the other wiring layers 22 and 27 are formed of gold . Therefore, it is possible to set the length of aluminum to an optimum length which is hard to cause the influence of the residual stress. That is, by selecting the length dimensions L1 and Lb of the upper wiring layers 22 and 27 shown in FIG. 1, it becomes easy to set the lower wiring layers 21 and 26 made of aluminum to dimensions that are hardly affected by the residual stress.

The second reason can be predicted as follows. When attention is paid to the electrode pad 16a shown in FIG. 1A, two wiring layers extending in a direction orthogonal to one another from one electrode pad 16a are formed as the first connection wiring layer 20 having the same length. As a result, the lower wiring layers 22, which are two aluminum wires, are equally spaced at equal distances from the electrode pad 16a on both sides thereof. Therefore, even if the internal stress remains in the aluminum, the stress acts on both sides of the electrode pad 16a uniformly. In addition, since the first detecting element portion 15a and the third detecting element portion 15c are arranged on both sides of the electrode pad 16a to have resistance changes of opposite polarities, stress remains in the lower wiring layer 22 Uniform stress is applied to the two detector elements 15a and 15c so as to eliminate the resistance change. In addition, by appropriately selecting the length L1 of the upper wiring layer 22, the stress acting on the detecting element portions 15a and 15c can be set to a good balance value.

The reason is the same in the relationship between the electrode pad 16c and the first connection wiring layers 20, 20 on both sides thereof. The electrode pads 16b and 16d are further provided with second connection wiring layers 25 having the same length on both sides thereof. Therefore, this structure also has a good balance, and even if the stress remains in the lower wiring layer 26, it works well with respect to the detecting element portion.

(Example)

As the first to fourth embodiments, the MEMS sensor 1 having the structure shown in Figs. 1 to 3 was simulated. The dimension of one side of the square shown in Fig. 1 was 500 mu m, and the thickness of the second substrate 12 was 5 mu m. The width dimensions of the upper wiring layers 22 and 27 were respectively 18 μm and the width dimensions of the lower wiring layers 21 and 26 were respectively 10 μm.

The length dimension of the second interconnecting wiring layer 25 was fixed at 60 탆 for La and 52 탆 for Lb. The length L0 of the first connection wiring layer 20 was fixed at 112 mu m and the length L1 of the upper wiring layer 22 was varied in each of the examples.

(Example 1): L1 = 52 탆

(Example 2): L1 = 60 占 퐉

(Example 3): L1 = 85 탆

(Example 4): L1 = 98 탆

4 is a plan view of the MEMS sensor 101 of (Comparative Example 1). The MEMS sensor 101 has electrode pads 116a, 116b, 116c, and 116d on the surface of the lower insulating layer 14a without forming the upper insulating layer 14b on the surface of the second substrate 12, And the first connection wiring layer 120 and the second connection wiring layer 125 are all formed of aluminum. The first connection wiring layer 120 and the second connection wiring layer 125 which are made of aluminum are electrically connected to the detection element portions 15a, 15b, 15c and 15d. The other structures are the same as those of the above embodiment.

5 and 6 show the MEMS sensor 201 of (Comparative Example 2). In this MEMS sensor 201, the electrode pads 16a, 16b, 16c and 16d are formed of gold on the surface 14c of the upper insulating layer 14b. The first connection wiring layer extending to both sides of the electrode pads 16a and 16c is formed only of the gold upper wiring layer 22 and the second connection wiring layer extending to both sides of the electrode pads 16b and 16d is formed of the gold- (27).

6, a connection layer 121 made of aluminum is formed between the conductive portion 22a of the upper portion of the upper wiring layer 22 and the detecting element portion 15a. This is the same in the upper wiring layer 27 and the conductive portion 27a of the detecting element layer. In Comparative Example 2, the first connection wiring layer and the second connection wiring layer are formed only of gold, and aluminum is formed only at the connection portion of the gold and the detection element.

Regarding Examples 1 to 4 and Comparative Examples 1 and 2, an initial detection output is obtained at atmospheric pressure as shown in Fig. Thereafter, the difference between the detection output when the temperature was raised from 25 DEG C to 80 DEG C and the temperature was lowered to 25 DEG C and the above-mentioned initial detection output were calculated to obtain the output fluctuation.

The results are shown in Fig. 8, the output fluctuation due to thermal hysteresis in Example 1 was -34.16 Pa, the output fluctuation in Example 2 was -27.98 Pa, the output fluctuation in Example 3 was -19.02 Pa, The output variation was +15.66 Pa. The output fluctuation of Comparative Example 2 was -111.11 Pa, and the output fluctuation of Comparative Example 2 was +52.66 Pa.

In the comparative example 1, since the connection wiring layer for conducting the electrode pad and the detecting element part is formed of aluminum over the entire length, the range of the stress remaining in the aluminum due to thermal hysteresis is widened and the detection element parts 15a, 15b, 15c, and 15d due to thermal hysteresis, and the output fluctuation due to thermal hysteresis is increased.

The first connection wiring layer 20 is uniformly arranged on both sides of the electrode pads 16a and 16c and the first connection wiring layer 20 is disposed on both sides of the electrode pads 16b and 16d And the second connection wiring layer 25 are uniformly arranged. As a result, an appropriate force with a good balance due to the residual stress of aluminum acts on the detecting element portions 15a and 15b and the detecting element portions 15c and 15d whose resistance values are opposite to each other, As a result, the output fluctuation is canceled and suppressed.

On the other hand, in Comparative Example 2, since almost no aluminum layer giving a balance of stress is present, a potential stress that is originally to be canceled by the stress of aluminum acts on the entire MEMS sensor. As a result, It is predicted that the output fluctuation of the opposite phase occurs.

As described above, in Embodiments 1, 2, 3, and 4, since the arrangement and length balance of the lower wiring layers by aluminum are good, output fluctuations due to thermal hysteresis can be suppressed. From Examples 1, 2, 3 and 4, a preferable range (L1 / L0) of the ratio of the length L1 of the upper wiring layer 22 to the length L0 of the first connection wiring layer 20 is 0.46 to 0.88 .

From FIG. 8, the output fluctuation becomes extremely small in the range from the third embodiment to the fourth embodiment. Therefore, it is more preferable that L1 / L0 is 0.76 to 0.88.

1: MEMS sensor
2: SOI substrate
11: a first substrate
11a:
11b:
12: second substrate
12a:
12b: wiring part
14: Insulating layer
15a, 15b, 15c and 15d:
16a, 16b, 16c, 16d: electrode pads
20: first connection wiring layer
21: Lower wiring layer
22: upper wiring layer
25: second connection wiring layer
26: Lower wiring layer
27: upper wiring layer

Claims (11)

1. A MEMS sensor comprising a first substrate and a second substrate each of which is a silicon substrate,
Wherein the first substrate has a space portion and a frame body portion surrounding the space portion, the second substrate has a sensing portion capable of being deformed to be deflected so as to face the space portion, and a sensing portion for sensing the sensing output in accordance with the bending deformation of the sensing portion An element portion is formed,
An insulating layer is formed on a surface of the second substrate, an electrode pad is formed on a surface of the insulating layer, a connection wiring layer is formed between the electrode pad and the detecting element portion,
Wherein the interconnecting wiring layer comprises a lower wiring layer formed of aluminum which is formed between the second substrate and the insulating layer and connected to the detecting element portion and an upper wiring layer extending from the electrode pad on the surface of the insulating layer, Wherein the upper wiring layer is formed of a conductive metal material having a smaller fluctuation in residual stress due to temperature change than aluminum and the upper wiring layer and the lower wiring layer are electrically connected to each other at an opening provided in the insulating layer, . The method according to claim 1,
Wherein the second substrate has a square shape and the electrode pads are located at all corner portions of a square, electrode pads provided on one diagonal line of the square are formed as first electrode pad pairs, and electrode pads provided on the other diagonal line A second electrode pad pair,
The plurality of first connection wiring layers extending from the first pair of electrode pads have the same length and the plurality of second connection wiring layers extending from the pair of second electrode pads are respectively the same length, And the length of the second connection wiring layer is different. 3. The method of claim 2,
The ratio of the lengths of the lower wiring layer and the upper wiring layer of the first connection wiring layer is set such that the ratio of the length of the lower wiring layer to the length of the lower wiring layer and the upper wiring layer in the second connection wiring layer is large MEMS sensors. The method according to claim 1,
Wherein the second substrate has a square shape and the electrode pad is located at every corner of the square, and the connection wiring layer is formed in parallel with each side of the square, and the length of the connection wiring layer, Is the same for each side of the square. The method according to claim 1,
Wherein the wiring pattern of the connection wiring layer is rotationally symmetric with respect to the center of the second substrate at a center of 180 degrees. 6. The method according to any one of claims 1 to 5,
Wherein the upper wiring layer is formed of gold. 6. The method according to any one of claims 1 to 5,
The total length of the connection wiring layer except for the conductive part between the lower wiring layer and the detection element part and the electrode pad is L0 and the total length of the connection wiring layer excluding the electrode pads and including the conductive parts between the upper wiring layer and the lower wiring layer, L1 / L0 is 0.46 to 0.88, where L1 is the length of the MEMS sensor. 8. The method of claim 7,
A MEMS sensor wherein L1 / L0 is 0.76 to 0.88. 6. The method according to any one of claims 1 to 5,
Wherein the electrode pad is formed of a conductive material having a smaller fluctuation in residual stress due to temperature change than aluminum. 10. The method of claim 9,
Wherein the electrode pad is formed of any one of gold, silver, and copper. 6. The method according to any one of claims 1 to 5,
Wherein a supporting substrate bonded to the second substrate is provided on the side opposite to the second substrate, the space portion is closed, and the sensing portion is deformed to a pressure of the gas.

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