JPH06201492A - Force conversion element - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a high-performance force conversion element with high element sensitivity even when the offset voltage is 0 when no force is applied. A Si single crystal body 30 having a (011) plane,
<001> direction and <00-1> of Si single crystal 30
A pair of input electrodes 60a and 60b formed in the direction
A pair of output electrodes 62a and 62b formed in the <010> direction and the <0-10> direction, and (0
11) A force transducing element including a force transmission block body 40 joined to the surface and a support pedestal 50 joined to the surface of the Si single crystal body 30 opposite to the joining surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a force converting element, and more particularly to a force converting element for converting a compressive force into an electric signal by utilizing the piezo resistance effect of a semiconductor.

[0002]

2. Description of the Related Art Conventionally, force conversion elements utilizing the piezoresistive effect of semiconductors are well known, and are used as pressure detectors, load cells, and pressure detectors for high temperature fluids such as combustion pressure of internal combustion engines. ing.

A semiconductor S is one of such force conversion elements.
Those using i are generally used. For example, π '
One using a scheme of current, voltage, power parallel type called ₁₁ type, those using the method of current-voltage parallel-force orthogonal called Pai' ₁₃ type, current, voltage, and power called Pai' ₆₃ type There is an orthogonal type detection system.

[0004] FIG. 14, the force transducer using a method of detecting the current, voltage, power parallel Pai' ₁₁ type is shown. In this force conversion element, input electrodes 11, 11 'and output electrodes 12, 12' are provided on the (110) plane 10a of the Si single crystal body 10 in the <1-10> direction thereof.

The Si single crystal body 10 is bonded to the strain generating material 16 via an adhesive material 14. The input electrodes 11, 11 '
Is supplied with a constant current from the power supply 18 and outputs an electric signal corresponding to the force T ₁ applied in the <1-10> direction to the output electrode 1
The difference between the output potentials 2 and 12 'is measured by the measuring device 20. In FIG. 14, the input / output electrode direction (<1-10
> Direction) is a single axis, the same plane on the Si single crystal body 10 is a direction orthogonal to the first axis, and a direction orthogonal to both the directions of the first and second axes (the <110> direction) is the third axis. .

The force conversion element is composed of the flexure material 16
In addition, when a force in the <1-10> direction of the Si single crystal body 10 is applied, the force is electrically detected as a voltage using the measuring device 20.

That is, in this force conversion element, an offset voltage proportional to the input resistance value is generated before the force is applied. This offset voltage V _OFFSET is expressed by the following equation.

[Equation 1] Here, ρ is the specific resistance of the Si single crystal body 10, b is the distance between the input and output electrodes, t is the thickness of the Si single crystal body 10, w is the width of the Si single crystal body 10, and I _supply is the applied current. is there.

When the above-mentioned force is applied to the strain generating member 16, a voltage V _out expressed by the following equation is output between the input and output electrodes of the Si single crystal body 10.

[Equation 2] Here, T ₁ is generated on the Si single crystal body <1-1.
It is a stress component in the 0> direction (uniaxial direction).

By the way, this force conversion element is composed of the input electrode 1
1, 11 'and the output electrodes 12, 12' are common. Therefore, as shown in the above equation 1, even when there is no load,
There is a problem that a large offset voltage V _offset represented by the product of the resistance value between the input and output electrodes and the applied current I _supply occurs. In particular, there has been a problem that the value of the offset voltage fluctuates greatly due to temperature changes, and this offset voltage appears as a large error component.

Further, when the element output is amplified by an amplifier, there is a problem that the structure becomes complicated.

[0011] Such order to solve the problem of the offset voltage, current, voltage, power orthogonal Pai' ₆₃ type detection techniques have also been proposed. This detection technology has a configuration in which a plurality of gauges using the current / voltage parallel force vertical π ′ ₁₃ type effect are equivalently arranged in a bridge and the outputs thereof are taken out.

[0012] Figure 15 is a force transducer according to the detection technique of the Pai' ₆₃ is shown.

This force conversion element is composed of (1
The force transmission block body 22 is joined to one surface of the (10) surface, and the support pedestal 24 is joined to the other (110) surface. Then, one (110) of the Si single crystal bodies 9
On the plane, the pair of electrodes 25, 25 'is rotated from the <001> direction toward the <1-10> direction by 45 °.
Forming another pair of electrodes 26, 26 'in the direction rotated by 135 °, one of which is used as an input electrode,
The other is used as an output electrode.

Then, a constant voltage is applied to the input electrodes 25 and 25 ', and the compressive force W applied perpendicularly to the (110) plane is read as a potential difference between the output electrodes 26 and 26' (Japanese Patent Laid-Open No. 62-190409). ).

[0015] In this output detection method, the output voltage is expressed using a piezoresistance coefficient _π'63. If the input electrode direction is one axis, the output electrode direction orthogonal thereto is two axes, and the force application direction orthogonal to both directions 1, 2 is three axes, the output voltage value is expressed by the following equation.

[Equation 3] Here, k is a coefficient determined by the shape of the element.

The force conversion element thus constructed is represented by a bridge circuit shown in FIG. 16 in terms of an equivalent circuit. That is, this type of force conversion element has an equivalent circuit,
It also had equivalently bridge arrangement a plurality of gauges using effect of the current-voltage parallel force perpendicular Pai' ₁₃ type.

As described above, this force conversion element has a structure in which the offset voltage is set to 0V by forming a bridge structure in terms of resistance change in terms of an equivalent circuit.

On the other hand, in this force conversion element, when viewed from the simple equivalent circuit shown in FIG.
The resistance in the 1-10> direction changes from R by ΔR due to stress, but the two resistances in the <001> direction hardly change. Therefore, the output of this equivalent circuit is expressed by the following equation, where R is the resistance value when no load is applied and ΔR is the increase in resistance due to the piezoresistance effect in the <1-10> direction when a load is applied. .

[Equation 5] Further, the increase amount of the output voltage of the current / voltage parallel force vertical π ′ ₁₃ type element due to the load application is approximately represented by the following equation using the expression similar to the above-mentioned equation 5.

[Equation 6]Therefore, comparing Equations 5 and 6 above,
The force conversion element is an electric power conversion element using the force conversion element shown in FIG.
Flow, voltage, force parallel π '₁₁Type detection method and bridge configuration
Current, voltage, flat with a large offset voltage
Π 'of power orthogonal ₁₃Smaller element output than type detection method
There was a problem that the output would be about half.

[0019] This is as shown in Table 1, when comparing the piezoresistance coefficient Pai' ₁₃ and Pai' ₆₃ serving as a main element output, evident from the fact that value is about one-half is there.

[Table 1] When the output voltage of the force conversion element shown in FIG. 15 is actually obtained,
It will be as follows.

For example, the output when 1 V is applied as the input voltage V _supply and the stress T ₃ = 15 kg / mm ² is applied, assuming k = 1, is calculated and expressed by the following equation.

[Equation 4] However, in this conventional force conversion element, k is smaller than 1 because of the electrode configuration and the like. FIG. 17 shows the actual output characteristic of this force conversion element. As is clear from the characteristics shown in the figure, since k is smaller than 1 in the conventional element, the element output is 23 m, which is smaller than the value of the mathematical expression 4.
It becomes V.

In addition to this, in each of the force conversion elements described above,
There is a problem in that the element output includes an error due to variations in each shape of the member at the time of manufacturing the element, an error in a mounting position, and the like. For example, in the force conversion element shown in FIG. 15, there are variations in the shapes of the force transmission block 22 and the support pedestal 24, and these blocks 2 with respect to the Si single crystal body 9.
2, due to variations in the mounting position of the support pedestal 24,
There is a problem that a relatively large error component is included in the element output.

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of such conventional problems, and an object thereof is to provide an offset voltage of 0 when there is no load, and a deviation of a shape when manufacturing an element. The purpose of the present invention is to obtain a force conversion element that has a small output error due to variations in the mounting position and has a high sensitivity of the element itself.

[0023]

To achieve the above object, the present invention provides a (011) plane or a (0-
1-1) Si single crystal formed to have a plane,
<001> direction and <00-1> of the Si single crystal body
Has a pair of first electrodes formed in a direction and a pair of second electrodes formed in a <010> direction and a <0-10> direction, and one of these is used as an input electrode and the other is used as an output electrode. A plurality of electrodes, a force transmission block body joined to the pressure receiving surface of the Si single crystal body and transmitting the applied compressive force perpendicularly to the crystal surface, and a force transmission block body on the opposite side of the pressure receiving surface of the Si single crystal body. A support pedestal joined to the surface,
The single crystal body is configured to generate a large tensile stress in the <01-1> direction and the <0-11> direction together with the compressive stress in the <011> direction as the compressive force is applied in the <011> direction. Is characterized by.

Here, it is preferable that the pressure receiving surface of the Si single crystal body is formed so that its cross-sectional shape and area are equal to the joint cross-sectional shape and cross-sectional area of the force transmission block body.

Further, it is preferable that the surface of the Si single crystal body opposite to the pressure receiving surface is formed so that its sectional shape and area are equal to the sectional shape and sectional area of the support pedestal.

Further, it is preferable that the rigidity of the force transmission block and the support pedestal be smaller than that of the Si single crystal.

When a p-type Si single crystal is used,
Impurity concentration is about 5 × 10 ¹⁸ (/ cm ³ ) or about 2
It is preferably set to × 10 ²⁰ (/ cm ³ ).

(Points of Interest and Concept of the Invention) In the prior art described above, only the single component of the strain (stress) generated in the force conversion element is considered, and as a result,
The force could not be detected effectively.

Therefore, the inventor of the present invention makes sure that all four bridge resistances of the equivalent circuit of the force conversion element are changed effectively.
It was conceived that a force conversion element having a large output can be obtained by selecting the crystal direction of the i single crystal and the force application direction. When the coordinates of the orthogonal coordinate system are 1, 2 and 3 axes, the stress is represented by vertical stress components T1 to T3 and shear stress components T4 to T6 parallel to the respective axes. Therefore, the element structure is such that the stress component T ₁ in the direction in which the force is applied and the other secondary stress components T 2 to T 6 effectively act in the direction of improving the element output. As a result, the device output is improved.

FIG. 5 shows an FEM (Finite Element) of the stress distribution generated when a compressive force is applied to the force conversion element of the present invention.
Method Finite element method) The analysis results are shown. The force conversion element used for this analysis is a glass having a rectangular cross section on the upper and lower surfaces of the Si single crystal body as in the case of the Si single crystal body, having the same cross sectional area, and having a lower rigidity than the Si single crystal body. A structure in which the above materials are joined as a force transmission block body and a support pedestal is used. Here, the (011) plane that exerts a compressive force on the Si single crystal body is formed in a rectangular shape. The <011> direction is one axis, the <0-11> direction is two axes, and the <100> direction is three axes.

A force conversion element having such a structure is used so that a force is applied perpendicularly to the bonding surface of the Si single crystal body.
The result of FEM analysis of the stress distribution obtained in this case by applying a compressive force in the 1> direction is shown in FIG. Si
It can be seen that a compressive stress T ₁ represented by a negative sign is generated in the entire single crystal body.

FIG. 6 shows the stress component T2 in the biaxial direction of the Si single crystal body, and FIG. 7 shows the stress component T3 in the triaxial direction of the Si single crystal body.

According to these analysis results, when the cross-sectional area of the structure shown in FIG. 5 is a rectangle in which l ₂ / l ₁ is 1 or more, in the Si single crystal, the direction of the short side of the rectangle (biaxial direction)
It was found that a large tensile stress T2 is generated in

By the way, it is known that the piezoresistance coefficient on the (100) plane of a p-type Si single crystal is as shown in Table 2.

[Table 2] Here, π ′ _ij may be considered as a value corresponding to the amount of resistance change in the i direction due to the stress in the j direction.

The inventor of the present invention effectively uses π ′ ₁₁ , π ′ ₂₂ , and π ′ ₁₂ having a large absolute value among these piezoresistive coefficients, and only one direction is generated with the application of the compressive force in the axial direction. It was conceived that not only the stress component of No. 3 but also the tensile stress component of the stress generated in the two directions and the three directions are superposed. Then, each bridge resistance expressed as an equivalent circuit can maximize the element output,
Realized the element configuration.

The configuration will be described below.

(Structure of the Invention) FIG. 1A shows the main structure of the force conversion element of the present invention. FIG. 1B shows the direction of each surface of the Si single crystal body. The force conversion element shown in the figure has a Si single crystal body 30 formed to have a (011) plane as a surface to which a compressive force is applied, and a force transmission bonded to the (011) plane of the Si single crystal body 30. Block body 4
0 and a support pedestal 50 bonded to the (0-1-1) plane of the Si single crystal body 30.

Electrode forming surfaces 32a and 32b are formed in the <010> direction and the <0-10> direction of the Si single crystal body 30, and a pair of first electrodes 60a and 60b are provided therein.

Furthermore, <001 of the Si single crystal 30 is formed.
> And <00-1> direction in the electrode forming surfaces 34a, 34b
And a pair of second electrodes 62a and 62b are provided therein.

Then, as shown in FIG. 2, one of a pair of electrodes, for example, the first electrodes 60a and 60b from the power source 64 is supplied.
A voltage is applied to the whole of the Si single crystal body 30 to supply a current.

Then, a voltage output proportional to the compressive force W acting on the force transmission block 40 is taken out through the other electrode, for example, the second electrodes 62a and 62b, and measured by the measuring device 66.

[0042]

The operation of the force conversion element of the present invention is different from that of the conventional force conversion element in which an elongated gauge is formed in a certain direction on silicon, so that the current along the orthogonal coordinate system as described in the prior art is used. -It cannot be explained by a simple detection method using voltage and force.

First, the input voltage 60 of the force conversion element of the present invention.
It is assumed that a constant voltage is applied between a and 60b.

When no force is applied to the force conversion element, F
According to the EM analysis, a current as shown in FIG. 8 flows through the Si single crystal body 30. At this time, both output electrodes 62a, 62
The potential difference between b is 0V.

Here, the local coordinate system is set to <01-1>, <01> based on the direction of the crystal plane of the Si single crystal body 30.
1> and <100> directions are defined.

Next, when a force is applied to the force transmission block 40 of the force conversion element in the <011> direction, the above-mentioned FIG.
7 to 7, a compressive stress T1 in the <011> direction, which is proportional to the applied force W, is generated in the Si single crystal body 30, and further in the <01-1> direction and the <0-11> direction. Tensile stress T ₂ occurs. The output due to the shear stress component is small as a whole and can be ignored. Also, <100
The amount of change in resistance due to the stress component T3 in the> direction is also related to the change in resistance in the uniaxial and biaxial directions.
Omitted because ´ ₁₃ and π´ ₂₃ are small (see Table 2).

With the application of the compressive force in the <011> direction, the Si single crystal 30 more effectively generates the tensile stress T ₂ in the <01-1> direction and the <0-11> direction. Various configurations can be adopted as required. For example, as shown in FIG. 1, when the contact (011) of the Si single crystal body 30 with the force transmission block body 40 has a rectangular shape, the length l _{1 in the} <01-1> direction is ,
The ratio l ₂ / l ₁ to the length l ₂ in the <100> direction is preferably 1 or more and 2 or less. Furthermore, the length l _{1 of} the Si single crystal body 10 in the <01-1> direction and the height <0.
The ratio l ₃ / l ₁ to the length l ₃ in the 11> direction is preferably 1 or more and 3 or less.

In order to explain the output of the force conversion element of the present invention, the force conversion element described above is expressed as a simplified equivalent circuit in consideration of the above-mentioned generated stress, resulting in a full bridge circuit as shown in FIG. Here, ΔR ₁ , ΔR ₂ , and Δ
R ₃ and ΔR ₄ are piezoresistive coefficients π ′ ₂₂ , π ′ ₂₁ , and π ′.
_11, the resistance change due to the effect of Pai' _12, the amount of change is expressed by the following equation.

[Equation 7]

[Equation 8]

[Equation 9]

[Equation 10] Here, π ′ _ij is a value shown in Table 2 and is a value proportional to the amount of change in resistance in the i direction based on the stress in the j direction. T
_i is the stress in the i direction, and R is the resistance value of the element.

The output of the force conversion element represented by this equivalent circuit becomes the voltage at the output end of the full bridge circuit, and
Expressed as 1.

[Equation 11] Than piezo values of Table 2, the relationship _π'11 = _π'22 = -π' ₁₂ is established. Therefore, from the above equations 7 to 10, ΔR
The relation of ₁ = −ΔR ₃ and ΔR ₂ = −ΔR ₄ is established, and as a result, the relation shown by the following equation is established between each ΔR.

[Equation 12] By substituting the equation 12 into the equation 11, the equation 11 is simplified as follows.

[Equation 13] Here, a voltage of 1 V is applied to the input electrodes 60a and 60b of the force conversion element to apply 15 kg / mm to the force transmission block body 40.
Consider the case where a pressure of ² is applied. As each stress value generated at this ^{time, T1 = -15kg / mm 2,} T2 = 1.
Using an average stress value of 5 kg / mm ² , input voltage 1 V
The output per hit is ΔV = 109 (mV
/ 15 kgV). Conventional, with a force transducer offset voltage using a piezoresistive effect of 0V type, maximum value of the output is the current, voltage, power orthogonal Pai' ₆₃ type 49 (mV / 15kgV). Therefore, the force conversion element of the present invention can obtain the element output higher than that of the conventional element from the simple calculation formula described above.

Therefore, according to the present invention, it is possible to obtain a force conversion element having a high element sensitivity while the offset voltage is 0 when no force is applied.

Further, in the force conversion element of the present invention, as shown in FIG. 8, a current is made to flow over the entire surface of the Si single crystal body 30. For this reason, unlike the case where a thin gauge is formed on the Si single crystal body, it is possible to greatly reduce the output error due to the variation in the shape at the time of manufacturing the element, the displacement of the mounting position, and the like.

In the above description, the Si single crystal 30 is used.
The case where the pressure receiving surface of (011) is set to (011) has been described as an example, but the present invention is not limited to this, and the pressure receiving surface of (0-1-
1) The surface may be used.

[0053]

As described above, according to the present invention,
Even if the offset voltage is 0 when no force is applied, there is an effect that a high-performance force conversion element having high element sensitivity can be provided.

In addition to this, by adopting a structure in which an electric current is caused to flow in a wide range of the Si single crystal body, even if there is an error in the shape of each part at the time of manufacturing the element or its mounting position, the output error generated is small. Therefore, it is possible to obtain a highly accurate force conversion element.

Other Inventions Further, in the force conversion element of the present invention, the Si single crystal body may be formed in layers on the side surface of the base having the pressure receiving surface.

Such a force converting element includes a base having a pressure receiving surface, a force transmitting block body joined to the pressure receiving surface of the base and transmitting the applied compressive force perpendicularly to the pressure receiving surface, A support pedestal joined to the surface of the base opposite to the pressure receiving surface and a layer formed on the side surface of the base in a layer of (011) or (0-1-) in the direction of compressive force applied to the pressure receiving surface. 1) A current-oriented Si single crystal body facing the plane, a pair of first electrodes formed in the <001> direction and the <00-1> direction on the side surface of the current conduction Si single crystal body, and <010 A pair of second electrodes formed in the <> direction and the <0-10> direction, a plurality of electrodes using one of them as an input electrode and the other as an output electrode, and the Si single crystal for energization As the body applies compressive force in the <011> direction to the base, <011>1> by forming so that the tensile stress is generated in the direction and <011> directions, be configured.

[0057]

The preferred embodiments of the present invention will now be described in detail with reference to the drawings.

First Embodiment FIG. 1 shows a perspective view of a force converting element according to a first embodiment of the present invention, and FIG. 2 shows a measuring circuit using this force converting element. ing. In addition, in FIG. 1 and FIG.
The <011>, <01-1>, and <100> directions are simply defined as 1-axis, 2-axis, and 3-axis directions.

The force conversion element of this embodiment has a specific resistance of 20Ω.
cm of the (011) plane of the p-type Si single crystal 30 is <01
It is formed in a rectangular shape having a length in the -1> direction of l ₁ and a length in the <100> direction of l ₂ . Then, on the (011) plane and the (0-1-1) plane of the Si single crystal body 30,
A force transmission block body 40 and a support pedestal block 50 made of glass or ceramics having the same horizontal cross-sectional shape
However, they are joined by a joining technique such as anodic joining.

In the above, the Si single crystal body 30 <
Effectively <0 with the application of compressive force in the 011> direction
It is preferable to form the Si single crystal body 30 so that tensile stress is induced in the 1-1> direction and the <0-11> direction. To this end, for example, the (011) plane of the Si single crystal body 30 is formed in a rectangular shape, and the ratio l ₂ / l ₂ of the lengths l ₁ and l _{2 in} the <01-1> direction and the <100> direction is 1 ₂ / It is preferable to form l ₁ to 1 or more and 2 or less. Furthermore, the <01-1> direction of the Si single crystal 30 and <01-1>
The ratio l ₃ / l ₁ of the lengths l ₁ and l ₃ in the 1> direction is preferably 1 or more and 3 or less.

In the present embodiment, the rectangular (011) plane of the Si single crystal body 30 is formed with an aspect ratio of l ₁ : l ₂ = 2: 3. This gives <01
As the compressive stress is applied in the 1> direction, the tensile stress T ₂ is effectively generated in the <01-1> and <0-11> directions.

Further, the Si single crystal body 30 has a <0
10> direction, <0-10> direction, (010) plane, (0
-10) electrode forming surfaces 32a, 32b are formed, and a pair of input electrodes 60a, 60b formed of a metal such as aluminum on the electrode forming surfaces 32a, 32b.
Is provided.

Furthermore, with respect to these electrodes, <100>
In the direction rotated by 90 ° about the axis, that is, in the <001> direction and the <00-1> direction of the Si single crystal body 30, (0
Electrode forming surface 34 consisting of (01) plane and (00-1) plane
a, 34b are formed, and these electrode forming surfaces 34a, 34b are formed.
A pair of output electrodes 62a and 62b are provided on b using the same method.

Therefore, the Si single crystal body 30 of the embodiment is
Results in an octagonal prism.

FIG. 2 shows a circuit diagram using the Si single crystal body 30 of the embodiment. A constant voltage is applied from the power source 64 to the input electrodes 60a and 60b, and at this time, the output electrodes 62a and 62b. The voltage output from is measured by the measuring device 66.

In the force conversion element having such a structure, when no force is applied to the force transmission block body 40, the potential difference from both output electrodes 60a and 60b is 0V.

Then, <011 of the force transmission block body 40
When a force W is applied in the> direction, a compressive stress T ₁ mainly in the <011> direction and a tensile stress T ₂ in the <01-1> direction are generated in the Si single crystal body 30. By superimposing the piezoresistive effect of these stresses, the voltage ΔV shown in the above-mentioned expression 13 is output from the force conversion element.

In FIG. 4, the power source 64 is connected to the electrodes 60a, 60.
The value of the output voltage obtained when the voltage applied between b is set to 1 V and the pressure applied to the force transmission block body 40 is changed is shown. The solid line in the figure is the measured data of this embodiment, and the dotted line is the output characteristic of the conventional force conversion element shown in FIGS. As shown in the figure, 15k
When a pressure of g / mm ² was applied, a voltage of 43 mV was actually obtained in the force conversion element of the example. This output voltage is about twice the output voltage 23 mV (see FIG. 17) actually obtained when the same pressure is applied to the conventional force conversion element.

Second Embodiment FIG. 9 shows a perspective view of a force conversion element according to a second embodiment of the present invention, and FIG. 10 shows a measurement circuit diagram using this force conversion element. .

The feature of the force conversion element of the present embodiment is that it has a quadrangular prismatic structure whose horizontal cross-sectional shape is the same in all parts.

For this reason, in the force conversion element of the example, the p-type Si single crystal body 30 having a square pole structure with a specific resistance of 20 Ω · cm is used, and its rectangular (011) plane and (0
The length of the (1-1) plane in the <01-1> direction is l ₁ , <
The length in the 100> direction is set to l ₂ . Then, the (011) plane and (0−
The force transmission block body 40 and the support pedestal block 50 having the same horizontal cross-sectional area are joined to the (1-1) plane.

In the Si single crystal 30, the tensile stress T ₂ is effectively induced in the <01-1> direction and the <0-11> direction with the application of compressive force in the <011> direction. It is formed to have an aspect ratio of l ₁ : l ₂ = 1: 2.

Then, the <010> direction of the (0-11) plane, which is the side surface of the Si single crystal body 30, and the (01-1) direction.
In the <0-10> direction of the plane, a pair of input electrodes 60a, 6
0b is provided. <1 for these input electrodes
A pair of output electrodes in a direction rotated by 90 ° about the 00> axis, that is, in the (01-1) plane and the (0-11) plane of the Si single crystal body 30 in the <001> and <00-1> directions. 62a and 62b are provided.

A constant voltage is applied to the input electrodes 60a, 60b from the power supply 64, and the output voltage obtained from the output electrodes 62a, 62b is measured by the measuring device 66, as in the above embodiment. .

FIG. 11 shows an output characteristic diagram of the force conversion element of the embodiment. As shown in the figure, it was confirmed that the output voltage of the force conversion element of the example was ΔV = 54 mV when a pressure of 15 kg / mm ² was applied.

In the force conversion element of this embodiment, the p-type S
The impurity concentration of the i single crystal 30 is 5 × 10 ¹⁸ (/ cm ³ ).
Alternatively, in the case of 2 × 10 ²⁰ (/ cm ³ ), the voltage output ΔV
It is possible to construct a force conversion element that has little fluctuation with respect to temperature.

Third Embodiment FIG. 12 shows a perspective view of a force conversion element according to a third embodiment of the present invention. In the present embodiment, the second
Members corresponding to those in the embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The feature of this embodiment is that the input electrodes 60a, 60
The Si single crystal 30 to which a current is applied from
It is formed in layers on the side surface of the.

That is, the pressure receiving surface 82 of the base 80 is formed in a rectangular prism shape. This base 80
The force transmission block body 40 is joined to the pressure receiving surface 82 of the base plate 80 by the same method as in the above-described embodiment, and the other surface 84 of the base 80 is joined.
A support pedestal block 50 is joined to the.

On the side surface of the base 80, the Si single crystal bodies 30 to which current is applied by the input electrodes 60a and 60b are formed in layers. This Si single crystal 30
Is formed such that its (011) plane faces the direction of pressure application to the pressure receiving surface 82.

The specific structure of the force conversion element will be described below.
This will be described in more detail.

The force conversion element of the embodiment is the Si single crystal body 30.
First, the entire base 80 including is formed as an n-type Si single crystal body 100.

This n-type Si single crystal body 100 has
1) Pressure receiving surface 82 whose surface is joined to the force transmission block body 40
And the (0-1-1) plane is the plane 84 joined to the support pedestal block 50.

As described above, the force conversion element according to the example has (01) of the n-type Si single crystal body 100 functioning as the base 80.
The force transmission block body 40 is attached to the (1) plane and the (0-1-1) plane.
The support pedestal blocks 50 are joined together to form a rectangular columnar structure having a rectangular cross section.

Furthermore, the n-type Si single crystal 100 is
And a rectangle with its (011) of <01-1> direction of the surface length l _1, the aspect ratio of the <100> direction of the length l ₂ is l _1: l ₂ = _2: set to 3. Due to this, <0
With the application of compressive force in the 11> direction, effectively <01
The tensile stress T ₂ is induced in the −1> direction and the <0-11> direction.

The impurity concentration on the (100) plane of the n-type Si single crystal 100 is about 5 × 10 ¹⁸ (/ cm ³ ) or about 2 × 10 ²⁰ (/ cm ³ ) due to thermal diffusion or ion implantation. The p-type diffusion layer 70 is formed so as to have a size of ³ cm3.

This p-type diffusion layer 70 becomes the current-carrying Si single crystal body 30 formed in layers on the side surface of the base 80.

On the surface of the diffusion layer 70 (30) of the n-type Si single crystal 100, the <010> direction and the <010> direction are formed.
A pair of output electrodes 60a and 60b are provided in the 0-10> direction, and 90 ° with respect to these electrodes about the <100> axis.
Direction of rotation, ie <001> and <00-1>
A pair of output electrodes 62a and 62b are provided in the direction.

With the above structure, the force conversion element having the load-output characteristic shown in FIG. 13 can be obtained.

Particularly, in this embodiment, the n-type Si single crystal body 1 is used.
A diffusion layer 70 is formed on the (100) plane of No. 00 as the energizing Si single crystal body 30, and each electrode is provided on the diffusion layer 70. Therefore, by driving the force conversion element with a constant current using the input electrodes 60a and 60b, it is possible to obtain a so-called self-sensitivity temperature compensation type force conversion element in which the voltage output is always constant with respect to temperature.

In the third embodiment, the current-carrying Si is used.
As the single crystal layer 30, the n-type Si single crystal 100 (1
The case where the diffusion layer 70 is formed on the (00) plane has been described as an example, but the base 80 may have various configurations other than this. For example, the base 80 is an n-type S
In addition to i single crystal, SOI (Silicon onin)
substrate) or SIMOX (Separation)
by IMplanted OXygen), the Si single crystal layer on the surface can be used for energization.

With the above-described structure, the structure does not have a pn junction between the Si single crystal body 30 and the base 80, so that the leakage current is small even when used at high temperatures, and the high-temperature utility A conversion element can be formed.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made within the scope of the gist of the present invention.

For example, in the first, second and third embodiments, the case where the (011) plane side of the Si single crystal 30 or the n-type Si single crystal 100 is used as the pressure receiving surface has been described as an example. The present invention is not limited to this, and even if the (0-1-1) plane side is used as the pressure receiving surface and is formed so as to be joined to the force transmission block body, the same operational effect as that of the above-described embodiment can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic perspective explanatory view of a force conversion element according to a first embodiment of the present invention.

2 is an explanatory diagram of a measurement circuit using the force conversion element shown in FIG.

FIG. 3 is an explanatory diagram equivalently representing the force conversion element shown in FIG. 2 by a bridge circuit.

FIG. 4 is a load-output characteristic diagram of the force conversion element according to the first embodiment.

5A and 5B are explanatory diagrams of FEM analysis results of stress distribution when a compressive force is applied to the force conversion element shown in FIG.

6 is an FEM of a compressive stress distribution generated in the <0-11> direction when a compressive force is applied to the force conversion element shown in FIG.
It is explanatory drawing of an analysis result.

FIG. 7 is a diagram showing a case where a compressive force is applied to the force conversion element shown in FIG.
It is explanatory drawing of the FEM analysis result of the compressive stress distribution which generate | occur | produces in a <100> direction.

FIG. 8 is an explanatory diagram of an FEM analysis result of a current flowing when a force is not applied to the force conversion element shown in FIG. 1.

FIG. 9 is a schematic perspective explanatory view of a force conversion element according to a second embodiment of the present invention.

FIG. 10 is an explanatory diagram of a measurement circuit configured using the force conversion element according to the second embodiment.

FIG. 11 is a load-output characteristic diagram of the force conversion element of the second embodiment.

FIG. 12 is a schematic perspective explanatory view of a force conversion element according to a third embodiment of the present invention.

FIG. 13 is a load-output characteristic diagram of the force conversion element of the third embodiment.

FIG. 14 is a schematic explanatory view of a conventional force conversion element.

FIG. 15 is a schematic explanatory view of another conventional force conversion element.

16 is an explanatory diagram of a measurement circuit configured using the force conversion element shown in FIG.

FIG. 17 is a load-output characteristic diagram of the force conversion element shown in FIG.

[Explanation of symbols]

 30 Si single crystal body 40 Force transfer block body 50 Support pedestal 60a, 60b First electrode 62a, 62b Second electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Nonomura, Nagakute-cho, Aichi-gun, Aichi Prefecture 1-41 Yokomichi, Yokosui Central Research Institute Co., Ltd. (72) Shoji Takeuchi, Aichi-gun, Nagakute-cho, Aichi-gun 41, Yokoshiro Road Inside Toyota Central Research Institute Co., Ltd.

Claims (2)

[Claims] 1. A (011) plane or (0-
1-1) a Si single crystal formed so as to have a plane, and a <001> direction and <00-1> of the Si single crystal.
Has a pair of first electrodes formed in a direction and a pair of second electrodes formed in a <010> direction and a <0-10> direction, and one of these is used as an input electrode and the other is used as an output electrode. A plurality of electrodes, a force transmission block body that is joined to the pressure-receiving surface of the Si single crystal body, and transmits the applied compressive force perpendicularly to the crystal surface, and a force transfer block body on the opposite side of the pressure-receiving surface of the Si single crystal body. A support pedestal bonded to the surface, and the Si single crystal body having a compressive force in the <011> direction, <01-
A force conversion element having a configuration in which tensile stress is generated in the 1> direction and the <0-11> direction. 2. A base having a pressure receiving surface, a force transmission block body joined to the pressure receiving surface of the base and transmitting the applied compressive force perpendicularly to the pressure receiving surface, the pressure receiving surface of the base. A support pedestal joined to a surface opposite to the surface and a layer formed on a side surface of the base, and a (011) surface or a (0-1-1) surface is oriented in a direction in which a compressive force is applied to the pressure receiving surface. An energizing Si single crystal, a pair of first electrodes formed in the <001> direction and the <00-1> direction on the side surface of the energizing Si single crystal, and a <010> direction and a <0- A pair of second electrodes formed in the 10> direction, one of which is an input electrode,
A plurality of electrodes using the other one as an output electrode; and the Si single crystal body for energization, in association with application of a compressive force in a <011> direction to the base, <01-1> direction and <0- 11 is a force conversion element having a structure in which a tensile stress is generated in the 11> direction.