JP6192728B2 - Mechanical quantity measuring device and pressure sensor using the same - Google Patents

Description

  The present invention relates to a technique for measuring mechanical quantities such as stress and strain applied to an object to be measured, and in particular, a mechanical quantity measuring apparatus including a strain detection region constituted by an impurity diffusion resistor formed on a semiconductor substrate surface and The present invention relates to a pressure sensor using the same.

  As a device for measuring deformation (strain) of a measurement object, a metal foil strain gauge in which a metal resistor (metal foil) is disposed on a thin insulator has been well known for a long time. The metal foil strain gauge measures the change in electrical resistance value associated with the deformation of the metal foil following the deformation of the object to be measured, and converts it into a strain amount. The structure is simple and inexpensive, but with high accuracy. Because of this, it has been widely used. Metal foil strain gauges, on the other hand, have weak points such as that measurement errors are likely to occur when the temperature of the object to be measured changes, power consumption is high for constant driving, and a certain amount of installation area is required. have.

  As a device for overcoming these weak points of the metal foil strain gauge, a semiconductor strain sensor having a strain detection region (bridge circuit) composed of an impurity diffusion resistor formed on the surface of a semiconductor substrate has been developed. The semiconductor strain sensor can detect even small strains because the resistance change rate with respect to strain of the impurity diffusion resistor is several tens of times larger than that of the metal resistor of the conventional metal foil strain gauge ( That is, there is an advantage of high sensitivity to strain). In addition, by using a so-called semiconductor process such as photolithography for the formation of the impurity diffusion resistor, the impurity diffusion resistor can be finely patterned, and the entire semiconductor strain sensor can be reduced in size and area can be saved. Can be Furthermore, by making the impurity diffusion resistor finely patterned, all the resistors that make up the Wheatstone bridge circuit can be formed on the same substrate. There is also an advantage that it becomes smaller (measurement accuracy is improved).

  For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2007-263781) discloses a mechanical quantity measuring device that includes a strain detection unit on the surface of a semiconductor substrate and is attached to an object to be measured to measure strain. At least two or more sets of bridge circuits are formed, and one of the bridge circuits has a direction (longitudinal direction) in which a variation in resistance value is measured by passing a current <1 0 of the semiconductor single crystal substrate. A mechanical quantity measuring device is disclosed in which an n-type diffusion resistor parallel to the 0> direction is formed and another bridge circuit is formed by combining a p-type diffusion resistor parallel to the <1 1 0> direction. . According to Patent Document 1, it is supposed that a strain component in a specific direction generated in an object to be measured can be accurately measured.

Patent Document 2 (Japanese Patent Laid-Open No. 2012-47608) discloses a mechanical quantity measuring device using a bridge circuit formed on a semiconductor substrate, and the bridge circuit includes four bridge resistors R _v1 , R _v2 , R _h1. , R _h2 , each bridge resistor is composed of a plurality of diffused resistors, and the plurality of diffused resistors are arranged in a matrix on the semiconductor substrate, and the bridge resistors R _v1 , R _v2 are arranged in odd columns of the matrix. The plurality of diffused resistors arranged are selectively connected in series, and the bridge resistors R _h1 and R _h2 are selectively connected in series with the plurality of diffused resistors arranged in even columns of the matrix. A mechanical quantity measuring device is disclosed. According to Patent Document 2, it is possible to prevent occurrence of offset output of a bridge circuit due to stress generated due to a temperature change of an object to be measured, heat distribution on a semiconductor substrate, or a dose gradient of impurities of diffusion resistance. Has been.

  On the other hand, the mechanical quantity measurement using a strain sensor is based on the fact that the strain sensor also deforms following the deformation of the object to be measured. In order to perform highly accurate sensing over a long period of time, the strain sensor and the object to be measured The reliability of bonding with is very important. From this viewpoint, for example, in Patent Document 3 (WO 2012/144054), a measurement unit capable of measuring a mechanical quantity acting on a semiconductor substrate is provided in a central portion of the semiconductor substrate, and the semiconductor substrate is attached to an object to be measured. In the mechanical quantity measuring device for indirectly measuring the mechanical quantity that is attached and acts on the object to be measured, the outer peripheral part outside the central part of the semiconductor substrate is gathered in at least one place so as to be close to each other. A mechanical quantity measuring device having a plurality of impurity diffusion resistors forming a group, wherein the plurality of impurity diffusion resistors forming one of the groups are connected to each other to form a Wheatstone bridge, It is disclosed. According to Patent Document 3, the mechanical quantity measuring device disclosed in Patent Document 3 is capable of detecting by itself the separation between the mechanical quantity measuring device and the object to be measured.

JP 2007-263781 A JP 2012-47608 A International Publication No. 2012/144054

  Various technologies for more efficient combustion of fuel have been studied and adopted for the purpose of energy saving and exhaust gas cleaning in automobile engines, but in recent years, the demand for energy saving and exhaust gas cleaning has become increasingly strong. Yes. A typical combustion technology that aims to save energy is a technology that realizes combustion under conditions that are thinner than the stoichiometric air-fuel ratio, and a typical combustion technology that aims to reduce exhaust gas achieves stable and reliable combustion in the cylinder. Technology.

  In order to effectively realize these combustion technologies, precise control of fuel injection is indispensable. In realizing precise control of fuel injection, a pressure sensor related to injection pressure control is one of key parts.

  For example, in the common rail system for diesel engines, fuel pressure is further increased (for example, 2500 to 3000 atmospheres) in order to promote energy saving and exhaust gas cleaning, and higher pressure resistance against components. High durability and durability (long-term reliability) are strongly demanded. Further, among the components, the pressure sensor is a component that forms the basis of precision control, and further high accuracy is strongly demanded in addition to pressure resistance and durability.

  The semiconductor strain sensors described in Patent Documents 1 to 3 have excellent operational effects as described above. However, in order to achieve the latest required level for pressure sensors (especially high accuracy and long-term reliability), it has been found that further improvements are required in semiconductor strain sensors (mechanical quantity measuring devices) ( Details will be described later).

  Accordingly, an object of the present invention is to provide a semiconductor strain sensor (mechanical quantity measuring device) having higher accuracy and long-term reliability than conventional ones. Another object of the present invention is to provide a pressure sensor having higher accuracy and longer-term reliability than ever before by using the mechanical quantity measuring device.

  (I) One aspect of the present invention is a mechanical quantity measuring device having a strain detection region constituted by an impurity diffusion resistor formed on a semiconductor substrate surface, wherein the strain detection regions are arranged concentrically with each other. A plurality of Wheatstone bridges, and the innermost Wheatstone bridge among the plurality of Wheatstone bridges is a group of two resistors or a four-fold symmetric shape centered on the concentric axis. The other Wheatstone bridges among the plurality of Wheatstone bridges are composed of four resistor groups having a four-fold symmetry with the concentric axis as the axis, and constitute the Wheatstone bridge. Each of the four bridge resistors includes the impurity diffusion resistor that is a multiple of the number of the resistor groups of the Wheatstone bridge, Each of the resistor groups has at least one impurity diffusion resistor constituting the four bridge resistors.

  (II) Another aspect of the present invention is a pressure sensor in which a semiconductor strain sensor is joined on a metal diaphragm, wherein the semiconductor strain sensor is a mechanical quantity measuring device according to the present invention. A pressure sensor is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the mechanical quantity measuring apparatus which has higher precision and long-term reliability than before can be provided. Further, by using the mechanical quantity measuring device, it is possible to provide a pressure sensor having higher accuracy and longer-term reliability than ever before.

It is a plane schematic diagram which shows the outline | summary of the conventional semiconductor strain sensor used for experiment. It is the plane schematic diagram which shows the outline | summary of the pseudo pressure sensor used for experiment, and the cross-sectional schematic diagram of ab line. It is a cross-sectional schematic diagram which shows the mode of a deformation | transformation of a pseudo pressure sensor, and the graph which shows the relationship between the output voltage of a semiconductor distortion sensor, and time. It is the figure which represented typically the stress distribution concerning a solder joint layer when the pseudo pressure sensor is carrying out the bending deformation, and the creep deformation amount distribution of a solder joint layer. It is a plane schematic diagram which shows the outline | summary of the mechanical quantity measuring device which concerns on 1st Embodiment. The creep deformation distribution of the solder joint layer when the pseudo pressure sensor using the mechanical quantity measuring device according to the first embodiment is bending deformed, and the output voltage-strain diagram of each Wheatstone bridge are schematically shown. FIG. It is the figure which represented typically the output voltage-strain diagram of each Wheatstone bridge when the edge part of the mechanical quantity measuring device which concerns on 1st Embodiment peeled from the diaphragm. It is the plane schematic diagram and wiring system diagram which show an example of the innermost Wheatstone bridge in the mechanical quantity measuring device of 2nd Embodiment. It is the plane schematic diagram and wiring system diagram which show an example of the Wheatstone bridge other than the innermost periphery in the mechanical quantity measuring device of 2nd Embodiment. It is a plane schematic diagram which shows the outline | summary of the mechanical quantity measuring apparatus of 2nd Embodiment. It is a plane schematic diagram which shows the outline | summary of the mechanical quantity measuring device which concerns on 3rd Embodiment. The creep deformation distribution of the solder joint layer when the pseudo pressure sensor using the mechanical quantity measuring apparatus according to the third embodiment is bending deformed, and the output voltage-strain diagram of each Wheatstone bridge are schematically shown. FIG. It is the plane schematic diagram and wiring system diagram which show an example of a Wheatstone bridge other than the innermost periphery in the mechanical quantity measuring device of 4th Embodiment. It is a plane schematic diagram which shows the outline | summary of the mechanical quantity measuring apparatus of 4th Embodiment. It is a plane schematic diagram which shows the outline | summary of the mechanical quantity measuring apparatus of 5th Embodiment. It is a plane schematic diagram which shows the outline | summary of the mechanical quantity measuring apparatus of 6th Embodiment. It is a plane schematic diagram which shows the outline | summary of the mechanical quantity measuring apparatus of 7th Embodiment. It is a cross-sectional schematic diagram which shows an example of the pressure sensor which concerns on this invention.

(Experiment of offset phenomenon and elucidation of factors)
Automotive parts are particularly demanding fields regarding application temperature range, weather resistance, accuracy, long-term reliability, etc. among various industrial parts. The inventors of the present invention have been researching to satisfy the latest various demands on pressure sensors using semiconductor strain sensors, but the semiconductor strain sensors themselves and the pressure sensors themselves have no particular obstacles or damage. Regardless, we have found that the measurement results gradually change over a long period of time and the zero point is offset. This offset phenomenon is a problem related to accuracy and long-term reliability, and is a problem to be solved. Therefore, the present inventors conducted an experiment simulating the situation of the pressure sensor for automobile engines in order to elucidate the cause of the offset phenomenon.

FIG. 1 is a schematic plan view showing an outline of a conventional semiconductor strain sensor used in an experiment. The configuration and function of a conventional semiconductor strain sensor 10 will be briefly described with reference to FIG. The semiconductor strain sensor 10 includes a plurality of impurity diffusion resistors 2 formed on the surface of a silicon single crystal substrate 1, and the plurality of impurity diffusion resistors 2 include four bridge resistors R _v1 , R _v2 , R _h1 , The Wheatstone bridge 3 is connected to each other as R _h2 . The Wheatstone bridge 3 is connected to the power supply terminal 4 and the ground terminal 5, and the direction of current flowing through the four bridge resistors R _v1 , R _v2 , R _h1 , R _h2 is the <1 1 0> direction of the silicon single crystal substrate 1 and It is comprised so that it may become a direction perpendicular | vertical to it.

When the strain in the <1 1 0> direction of the silicon single crystal substrate 1 and / or the direction perpendicular thereto is applied to the semiconductor strain sensor 10, the impurity diffusion resistor 2 (that is, the four bridge resistors R _v1 , R _v2 , R _h1 , R _h2 ) change in resistance, and a potential difference is generated in the bridge voltage output. This potential difference is amplified by an amplifier circuit 6 formed in the silicon single crystal substrate 1 and taken out from the output terminal 7 as an electric signal. In this manner, the semiconductor strain sensor 10 can output an electrical signal corresponding to the amount of strain applied to the region where the Wheatstone bridge 3 is formed (strain detection region).

  FIG. 2 is a schematic plan view showing an outline of the pseudo pressure sensor used in the experiment and a schematic cross-sectional view taken along the line ab. As shown in FIG. 2, the pseudo pressure sensor 20 is obtained by joining the semiconductor strain sensor 10 via a solder joint layer 22 at a substantially central position of a metal plate 21 imitating a diaphragm. Since the pressure sensor for automobile engines is disposed in an environment of high temperature (for example, about 120 to 130 ° C.), the diaphragm and the semiconductor strain sensor are not usually joined with an organic adhesive, but with solder. Done by joining. The metal plate 21 is provided with a terminal block 23 to which the power supply terminal 4, the ground terminal 5, and the output terminal 7 of the semiconductor strain sensor 10 are connected.

Next, the experiment and the results will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view showing how the pseudo pressure sensor is deformed, and a graph showing the relationship between the output voltage of the semiconductor strain sensor and time. The experiment was performed in an environment of 130 ° C. First, “time = t1” is an initial state in which no stress is applied to the metal plate 21 of the pseudo pressure sensor 20 (that is, no strain is generated), and the output of the semiconductor strain sensor 10 at this time The voltage is V ₀ .

After that, when bending stress is applied to the metal plate 21 of the pseudo pressure sensor 20 over time “t2”, the metal plate 21 is distorted. Strain of the metal plate 21, propagates in the semiconductor strain sensor 10 through the solder bonding layer 22, the output voltage of the semiconductor strain sensor 10 is an output voltage V ₊ via a transient state from V _0. The bending stress applied to the metal plate 21 was a stress within the elastic deformation range of the metal plate 21.

Thereafter, when the same bending stress as that of “time = t2” was continuously applied to the metal plate 21 over “time = t3”, it was found that the output voltage of the semiconductor strain sensor 10 gradually decreased from V ₊ . After that, when the bending stress applied to the metal plate 21 is released over “time = t4”, the metal plate 21 returns to the “time = t1” state, and the output voltage of the semiconductor strain sensor 10 goes through the transient state to the output voltage V ₀ '. Here, the output voltage V ₀ ′ at “time = t4” is different from the output voltage V _{0 at} “time = t1”, and it was confirmed that the offset phenomenon of the zero point occurred.

  The same experiment was performed by changing the bending stress (that is, the amount of strain generated) applied to the metal plate 21 and the environmental temperature. As the bending stress was increased or the environmental temperature was increased, the output of the semiconductor strain sensor 10 was increased. It was confirmed that the voltage drop occurred faster and more greatly. On the other hand, no defects were found in the metal plate 21 and the semiconductor strain sensor 10 after any experiment. From these experimental results, it is considered that the zero point offset phenomenon may be caused by creep deformation in the solder joint layer 22.

  The creep deformation and offset phenomenon in the solder joint layer 22 will be considered. FIG. 4 is a diagram schematically illustrating the stress distribution applied to the solder joint layer and the creep deformation distribution of the solder joint layer when the pseudo pressure sensor is bending deformed. As shown in FIG. 4, since the semiconductor strain sensor 10 and the solder joint layer 22 are sufficiently small with respect to the metal plate 21, when the pseudo pressure sensor 20 is bent and deformed, stress concentration is caused at the end of the solder joint layer 22. Occurs. Here, the environmental temperature of this experiment is 130 ° C., and considering the melting point of the solder, this is a temperature region in which creep deformation can occur for the solder joint layer 22. As a result, it is considered that creep deformation occurs from the end of the solder joint layer 22. Further, since stress relaxation occurs in the solder joint layer 22 due to creep deformation, the amount of strain transmitted to the semiconductor strain sensor 10 is also reduced, and the output voltage is lowered. Thereafter, when the bending deformation of the pseudo pressure sensor 20 (the metal plate 21) is restored, stress in the opposite direction is applied to the stress-relieved solder joint layer 22. It is considered that the stress in the opposite direction is propagated to the semiconductor strain sensor 10 and the zero point offset phenomenon occurs.

  In order to suppress the offset phenomenon, it is desirable to suppress the creep deformation of the solder joint layer 22, and for that purpose, it is conceivable to use a solder material or a brazing material having a high melting point. However, it is not preferable to join the semiconductor strain sensor 10 using a bonding material having a melting point high enough to suppress creep deformation, because the possibility that the semiconductor strain sensor 10 itself is thermally deteriorated rapidly increases.

  From these facts, in the present invention, on the premise that the solder joint layer 22 undergoes creep deformation to some extent, the structure of a semiconductor strain sensor capable of correcting the influence has been intensively studied. The present invention has been completed as a result of this research.

  As described above, the mechanical quantity measuring device according to the present invention is a mechanical quantity measuring device including a strain detection region constituted by an impurity diffusion resistor formed on the surface of a semiconductor substrate, and the strain detection regions are mutually connected. A plurality of Wheatstone bridges arranged concentrically, and the innermost Wheatstone bridge among the plurality of Wheatstone bridges is a group of two resistors having a symmetrical shape about the concentricity; The Wheatstone bridge is composed of four resistor groups having a four-fold symmetry, and the other Wheatstone bridges of the plurality of Wheatstone bridges are formed of four resistor groups having a four-fold symmetrical shape about the concentric axis. Each of the four bridge resistors constituting the bridge is an impurity diffusion that is a multiple of the number of the resistor groups of the Wheatstone bridge. It consists antibodies, each of the resistor group is characterized by having each at least one said impurity diffusion resistors constituting the four bridge resistors.

In the mechanical quantity measuring device according to the present invention described above, the present invention can be improved or changed as follows.
(I) Each of the impurity diffusion resistors has a linear shape, and the resistor group has a structure in which a plurality of segments are arranged in series, and the segments are lines of the impurity diffusion resistors. The segment is composed of a plurality of impurity diffusion resistors arranged in parallel with each other, and has a rectangular shape as the segment.
(Ii) The adjacent segments in the resistor group are arranged so that the line directions of the impurity diffusion resistors constituting the segments are orthogonal to each other.
(Iii) The distance between the plurality of Wheatstone bridges is not more than the length of one side of the segment.
(Iv) The distance between the adjacent segments in the Wheatstone bridge is not more than the length of one side of the segment.
(V) The segment has a dummy resistor which has the same configuration as the impurity diffusion resistor but is not electrically connected.
(Vi) A correction arithmetic circuit for performing a correction calculation of the strain amount based on the output from each of the plurality of Wheatstone bridges is further provided on the semiconductor substrate.
(Vii) The correction calculation is performed based on the distance from the concentricity of each of the plurality of Wheatstone bridges in addition to the output from the plurality of Wheatstone bridges.
(Viii) The semiconductor substrate is a silicon single crystal substrate, and the direction of current flowing through the impurity diffusion resistor is a <1 1 0> direction of the silicon single crystal substrate or a direction orthogonal to the <1 1 0> direction It is connected to become.

  Further, as described above, the pressure sensor according to the present invention is a pressure sensor in which a semiconductor strain sensor is joined on a metal diaphragm, and the semiconductor strain sensor is the mechanical quantity measuring device according to the present invention described above. It is characterized by being.

The present invention can add the following improvements and changes to the pressure sensor according to the present invention described above.
(Ix) The joint is a solder joint.
(X) The pressure sensor is a pressure sensor for an automobile engine.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments described here, and can be appropriately combined and improved without departing from the technical idea of the present invention. In addition, the same code | symbol is attached | subjected to the same member and site | part, and the overlapping description is abbreviate | omitted.

(First embodiment of the present invention)
Here, the technical idea of the mechanical quantity measuring device according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a schematic plan view showing an outline of the mechanical quantity measuring device according to the first embodiment. In FIG. 5, in order to simplify the drawing, details of wiring (for example, wiring to each impurity diffusion resistor) are omitted.

As shown in FIG. 5, the mechanical quantity measuring device 30 (semiconductor strain sensor) according to the first embodiment is disposed concentrically on the surface of a semiconductor substrate (for example, a silicon single crystal substrate 1). It has two Wheatstone bridges A and B. The innermost Wheatstone bridge A is composed of two resistor groups RG _A1 and RG _A2 having a two-fold symmetric shape about the concentric axis. The Wheatstone bridge B other than the innermost circumference is composed of four resistor groups RG _B1 , RG _B2 , RG _B3 , and RG _B4 that have a four-fold symmetrical shape about the concentric axis. The Wheatstone bridges A and B are preferably formed sufficiently small (for example, 0.2 mm square) with respect to the size of the silicon single crystal substrate 1 (for example, 4 mm square).

Each of the four bridge resistors R _v1 , R _v2 , R _h1 , R _h2 constituting the Wheatstone bridge is composed of an impurity diffusion resistor that is a multiple of the number of resistor groups of the Wheatstone bridge. Specifically, in the Wheatstone bridge A composed of two resistor groups, the bridge resistance R _v1 is _composed of two impurity diffusion resistors r _Av11 and r _Av12 , and the bridge resistance R _v2 is the impurity diffusion resistor r _Av21. , R _Av22 , the bridge resistor R _h1 is composed of two impurity diffused resistors r _Ah11 and r _Ah12 , and the bridge resistor R _h2 is _composed of two impurity diffused resistors r _Ah21 and r _Ah22 . In the Wheatstone bridge B composed of four resistor groups, the bridge resistance R _v1 is _composed of four impurity diffusion resistors r _Bv11 , r _Bv12 , r _Bv13 and r _Bv14 , and the bridge resistance R _v2 is an impurity diffusion resistor. r _Bv21 , r _Bv22 , r _Bv23 , r _Bv24 , bridge resistance R _h1 is composed of four impurity diffusion resistors r _Bh11 , r _Bh12 , r _Bh13 , r _Bh14 , and bridge resistance R _h2 is impurity diffusion It _consists of four resistors, r _Bh21 , r _Bh22 , r _Bh23 , and r _Bh24 .

Furthermore, each of the resistor groups has at least one impurity diffusion resistor constituting four bridge resistors. Specifically, in the Wheatstone bridge A, the resistor group RG _A1 includes impurity diffusion resistors r _Av11 , r _Ah11 , r _Av21 , r _Ah21 , and the resistor group RG _A2 includes impurity diffusion resistors r _Av12 , r _Ah12. , R _Av22 , r _Ah22 . In the Wheatstone bridge B, the resistor group RG _B1 includes impurity diffusion resistors r _Bv11 , r _Bh11 , r _Bv21 , r _Bh21 , and the resistor group RG _B2 includes impurity diffusion resistors r _Bv12 , r _Bh12 , r _Bv22. , R _Bh22 , and the resistor group RG _B3 is made of impurity diffusion resistors r _Bv13 , r _Bh13 , r _Bv23 , r _Bh23 , and the resistor group RG _B4 is made of impurity diffusion resistors r _Bv14 , r _Bh14 , r _Bv24 , r _{Consists of Bh24} .

  As described above, the Wheatstone bridges A and B are arranged concentrically with each other and are composed of resistor groups having rotational symmetry, and each resistor group has all four bridge resistance elements. Yes. From this, each of the Wheatstone bridges A and B is detected within its own strain detection region (more strictly, in the region where the impurity diffusion resistors constituting the Wheatstone bridge are formed) The characteristic is that the signal is highly averaged and an averaged signal in the region can be obtained.

  Each of the Wheatstone bridges A and B is connected to the power supply terminal 4 and the ground terminal 5. A signal (potential difference in bridge voltage) obtained from the Wheatstone bridge A is amplified by an amplifier circuit 6 formed in the silicon single crystal substrate 1, and a signal obtained from the Wheatstone bridge B is an amplifier formed in the silicon single crystal substrate 1. Amplified by circuit 31. The signal amplified by the amplifier circuit 6 and the signal amplified by the amplifier circuit 31 are input to the correction arithmetic circuit 32 formed in the silicon single crystal substrate 1, and detected by the Wheatstone bridge A in the correction arithmetic circuit 32. Correction calculation is performed to calculate the true strain amount from the difference between the strain amount detected and the strain amount detected by Wheatstone bridge B, and the corrected calculation signal is taken out from the output terminal 7 (for details of the correction calculation, see Will be described later). As a result, even if creep deformation occurs in the solder joint layer joining the mechanical quantity measuring device 30 (semiconductor strain sensor), a signal (that is, the true strain amount) in which the influence is corrected can be obtained.

  Next, correction calculation will be described. FIG. 6 schematically shows the creep deformation distribution of the solder joint layer when the pseudo pressure sensor using the mechanical quantity measuring device according to the first embodiment is bent and the output voltage-strain diagram of each Wheatstone bridge. FIG.

As described above, since the Wheatstone bridges A and B are formed sufficiently small with respect to the size of the silicon single crystal substrate 1, the true strain amount generated in the Wheatstone bridges A and B is considered to be essentially the same. . However, under a high temperature environment, creep deformation occurs in the solder joint layer 22, and the amount of creep deformation increases toward the outer peripheral region of the mechanical quantity measuring device 30. That is, as shown in FIG. 6, than the Wheatstone bridge creep deformation amount of strain detection areas A epsilon _A, is larger creep deformation amount of the strain detection area of the Wheatstone bridge _{B ε B (ε A <ε} B) .

Since the stress relaxation occurs as the amount of creep deformation increases, the amount of strain propagated to the Wheatstone bridges A and B decreases more than the true amount of strain (the amount of strain in an ideal state without creep deformation). As a result, the output voltages Y _A and Y _B of the Wheatstone bridges A and B are lower than the ideal output voltage Y _i , and a difference occurs between the output voltages Y _A and Y _B of the Wheatstone bridges A and B. it is conceivable that. The difference between the output voltages Y _A and Y _B is considered to be proportional to the difference in the amount of creep deformation in the region where the Wheatstone bridges A and B are formed.

In the ideal state, the output voltage at zero strain is V _i0 , the output voltage at zero strain of Wheatstone bridge A is V _A0 , the output voltage at zero strain of Wheatstone bridge B is V _B0 , and the true strain is Assuming X and the strain sensitivity of the Wheatstone bridge as G, Y _i , Y _A , and Y _B can be expressed by the following equations (1) to (3), respectively.
Y _i = V _i0 + GX Equation (1),
Y _A = V _A0 + GX Equation (2),
Y _B = V _B0 + GX Equation (3).

  Here, it is assumed that the creep deformation distribution (relation between creep deformation and position) of the solder joint layer 22 can be approximated by a quadratic function curve. When the concentric Wheatstone bridges A and B are arranged in the central region of the silicon single crystal substrate 1, the position of the apex of the quadratic function curve of the creep deformation distribution overlaps the concentricity of the Wheatstone bridges A and B.

As described above, the concentric Wheatstone bridges A and B are formed sufficiently small with respect to the size of the silicon single crystal substrate 1, and the distance L _A between the concentricity and the Wheatstone bridge A, the concentricity and the Wheatstone bridge. It can be said that the distance L _{B to} B and the distance L _AB between the Wheatstone bridges A and B are sufficiently small. In a quadratic function curve, the vicinity of the apex or between adjacent two points can generally be approximated by a linear function. The distances L _A and L _B are defined as the average distance between the regions where the Wheatstone bridges A and B are formed and the centers thereof, and the distance L _AB is defined as the difference between L _A and L _B. .

Taking these into consideration, the difference between Y _A and Y _B can be expressed as in the following equation (4) from equations (2) and (3).
Y _A −Y _B = V _A0 −V _B0 Equation (4).

In addition, the difference between the output voltage V _{i0 at} zero strain in the ideal state and the output voltage V _{A0 at} zero strain of the Wheatstone bridge A is the distance L _A between the concentricity and the Wheatstone bridge A, between the Wheatstone bridges A and B. From the distance L _AB and the equation (4), it can be expressed as the following equation (5).
V _i0 −V _A0 = (V _A0 −V _B0 ) · L _A / L _AB = (Y _A −Y _B ) · L _A / L _AB Expression (5).

The following equation (6) is obtained from equations (1), (2), and (5), and the output voltage Y _i in the ideal state can be obtained. The output voltages Y _A and Y _B are obtained as measured values from the Wheatstone bridges A and B, and the distances L _A and L _AB are values obtained from the dimensions of the Wheatstone bridges A and B.
Y _i = Y _A + (V _i0 −V _A0 ) = Y _A + (Y _A −Y _B ) · L _A / L _AB (6)

  As described above, the mechanical quantity measuring device 30 according to the present embodiment performs the correction calculation shown in the equation (6) on the signals obtained from the Wheatstone bridges A and B in the correction arithmetic circuit 32, thereby performing soldering. Even if creep deformation occurs in the bonding layer 22, a signal (that is, a true strain amount) in which the influence is corrected can be obtained.

  Next, secondary effects of the mechanical quantity measuring device 30 according to the present embodiment will be briefly described. As described above, the pressure sensor using the mechanical quantity measuring device 30 can correct the effect of creep deformation in the solder joint layer 22, but excessive pressure is applied to the diaphragm or the environmental temperature rises excessively. In other words, the solder joint layer 22 may creep rupture, and the end of the mechanical quantity measuring device 30 (end of the silicon single crystal substrate 1) may start to peel from the diaphragm.

FIG. 7 is a diagram schematically showing an output voltage-strain diagram of each Wheatstone bridge when the end portion of the mechanical quantity measuring device according to the first embodiment is peeled from the diaphragm. As shown in FIG. 7, when the end of the mechanical quantity measuring device 30 (end of the silicon single crystal substrate 1) peels from the diaphragm, the output voltage before peeling at the Wheatstone bridge B disposed on the outer peripheral side. The output voltage Y _{B ′} is significantly lower than Y _B. In the output voltage Y _{B ′} , the output voltage V _{B′0 at} zero strain is lower than V _{B0 and the} proportional relationship with the true strain X is broken.

  That is, in the Wheatstone bridge B arranged on the outer peripheral side, the output signal shows a characteristic change earlier, so by comparing the signals obtained from the Wheatstone bridges A and B with the correction arithmetic circuit 32, the dynamics A sign of peeling of the quantity measuring device 30 can be detected. Moreover, a preventive maintenance function can be added by setting to output a predetermined signal when a sign of peeling is detected.

(Second embodiment of the present invention)
Here, a more specific example of the first embodiment will be described with reference to FIGS. FIG. 8 is a schematic plan view and a wiring system diagram showing an example of the innermost Wheatstone bridge in the mechanical quantity measuring device of the second embodiment. In the schematic plan view of FIG. 8, details of wiring (for example, wiring between impurity diffusion resistors) are omitted in order to simplify the drawing.

As shown in FIG. 8, the innermost Wheatstone bridge A ′ in the present embodiment is composed of two resistor groups RG _A1 and RG _A2 having a two-fold symmetrical shape. It has a structure in which a plurality of segments 33 are arranged in a row. The segment 33 includes a plurality of impurity diffusion resistors having a linear shape. In the segment 33, the plurality of impurity diffusion resistors are arranged so that their linear directions are parallel to each other, and the segment 33 has a rectangular shape.

Each of the four bridge resistors R _v1 , R _v2 , R _h1 , R _h2 constituting the Wheatstone bridge A ′ is composed of an impurity diffusion resistor that is a multiple of the number of resistor groups (here, 2). Specifically, the bridge resistor R _v1 consists of four diffusion resistors _{r Av11, r Av12, r Av13} , r Av14, bridge resistors R _v2 impurity diffused resistor _{r Av21, r Av22, r Av23} , r consists of four _Av24, bridge resistors R _h1 consists of four diffusion resistors _{r Ah11, r Ah12, r Ah13} , r Ah14, bridge resistors R _h2 are impurity diffused resistor r _Ah21, r _Ah22, r _Ah23 , R _Ah24 .

Further, the resistor group RG _A1, RG _A2 within segment 33 adjacent in the line direction of the impurity diffusion resistors composing them segments 33 are arranged such that the orthogonal relation to each other. Specifically, a segment 33 in the resistor group within RG _A1, an impurity diffusion resistor _{r Av11, r Av12, r Av21} , linear direction of r _Av22 is a silicon single crystal substrate 1 to <1 1 0> direction The impurity diffused resistors are arranged so as to be orthogonal to each other, and are connected so that a current flows in that direction. The segment 33 adjacent to the resistor group RG _A1 is _{arranged such that} the line direction of the impurity diffusion resistors r _Ah11 , r _Ah12 , r _Ah21 , r _Ah22 is the <1 1 0> direction of the silicon single crystal substrate 1 The impurity diffusion resistors are arranged and connected so that a current flows in that direction.

Similarly, in one segment 33 resistor group within RG _A2, impurity diffusion resistor _{r Av13, r Av14, r Av23} , linear direction of r _Av24 is perpendicular to <1 1 0> direction of the silicon single crystal substrate 1 The impurity diffusion resistors are connected so that a current flows in that direction. The segment 33 adjacent to the resistor group RG _A2 is _{arranged such that} the line direction of the impurity diffusion resistors r _Ah13 , r _Ah14 , r _Ah23 , r _Ah24 is the <1 1 0> direction of the silicon single crystal substrate 1 The impurity diffusion resistors are arranged and connected so that a current flows in that direction.

  As can be seen from FIG. 8 and the above description, each resistor group has all four elements of bridge resistance. From this, the Wheatstone bridge A ′ has a high in-plane detection isotropic property in its own strain detection region (in the region where the impurity diffusion resistor constituting the Wheatstone bridge is formed). The characteristic is that an averaged signal can be obtained.

  The segment 33 preferably has a dummy resistor 34 that has the same configuration as the impurity diffusion resistor but is not electrically connected. The dummy resistor 34 may be arranged in parallel to the impurity diffusion resistor constituting the segment 33 and sandwiching the bundle of the impurity diffusion resistor (in other words, on the outermost side in the segment). preferable. The formation of the dummy resistor 34 in such a positional relationship contributes to equalization of the dopant concentration of the impurity diffusion resistor constituting the Wheatstone bridge in the process of forming the impurity diffusion resistor.

  FIG. 9 is a schematic plan view and a wiring system diagram showing an example of a Wheatstone bridge other than the innermost circumference in the mechanical quantity measuring device of the second embodiment. In the schematic plan view of FIG. 9, details of wiring (for example, wiring between impurity diffusion resistors) are omitted to simplify the drawing.

As shown in FIG. 9, the Wheatstone bridge B ′ other than the innermost circumference in the present embodiment is composed of four resistor groups RG _B1 , RG _B2 , RG _B3 , and RG _B4 having a four-fold symmetrical shape. Each of the resistor groups has a structure in which a plurality of segments 33 are arranged in series. Similar to the Wheatstone bridge A ′ described above, the segment 33 includes a plurality of impurity diffusion resistors having a linear shape. In the segment 33, the plurality of impurity diffusion resistors are arranged so that their linear directions are parallel to each other, and the segment 33 has a rectangular shape.

Each of the four bridge resistors R _v1 , R _v2 , R _h1 , R _h2 constituting the Wheatstone bridge B ′ is composed of an impurity diffusion resistor that is a multiple of the number of resistor groups (here, 4). Specifically, the bridge resistance R _v1 is composed of 12 impurity diffusion resistors r _Bv11 , r _Bv12 , r _Bv13 , r _Bv14 ,..., R _Bv19 , r _Bv110 , r _Bv111 , r _Bv112 , and the bridge resistance R _v2 includes 12 impurity diffusion resistors r _Bv21 , r _Bv22 , r _Bv23 , r _Bv24 ,..., r _Bv29 , r _Bv210 , r _Bv211 , r _Bv212 , and the bridge resistor R _h1 is the impurity diffusion resistor r _Bh11. , R _Bh12 , r _Bh13 , r _Bh14 ,..., R _Bh19 , r _Bh110 , r _Bh111 , r _Bh112 , and the bridge resistance R _h2 is impurity diffusion resistors r _Bh21 , r _Bh22 , r _Bh23 , r _Bh24 ,..., R _Bh29 , r _Bh210 , r _Bh211 , r _Bh212 are included.

Similar to the Wheatstone bridge A 'described above, the segment 33 adjacent in the resistor group within RG _B1 ~RG _B4, as a relation to the line direction of the impurity diffusion resistors composing them segments 33 are perpendicular to each other It is arranged. For example, one segment 33 in the resistor group RG _B1 is a direction in which the line direction of the impurity diffusion resistors r _Bv11 , r _Bv12 , r _Bv21 , r _Bv22 is orthogonal to the <1 1 0> direction of the silicon single crystal substrate 1 The impurity diffusion resistors are connected so that a current flows in that direction. The segment 33 adjacent to the resistor group RG _B1 is _{arranged such that} the line direction of the impurity diffusion resistors r _Bh11 , r _Bh12 , r _Bh21 , r _Bh22 is the <1 1 0> direction of the silicon single crystal substrate 1 The impurity diffusion resistors are arranged and connected so that a current flows in that direction. Further, the segment 33 adjacent thereto is _{arranged so that} the line direction of the impurity diffusion resistors r _Bv13 , r _Bv14 , r _Bv23 , r _Bv24 is a direction perpendicular to the <1 1 0> direction of the silicon single crystal substrate 1. The impurity diffusion resistors are connected so that a current flows in that direction.

As can be seen from FIG. 9 and the above description, each of the resistor groups RG _{B1 to} RG _B4 has all four bridge resistance elements. From this, the Wheatstone bridge B ′ has a high in-plane isotropy of detection in its own strain detection region (in the region where the impurity diffusion resistor constituting the Wheatstone bridge is formed). The characteristic is that an averaged signal can be obtained.

  Similarly to the Wheatstone bridge A ', the segment 33 of the Wheatstone bridge B' preferably has a dummy resistor 34 that has the same configuration as the impurity diffusion resistor but is not electrically connected.

  FIG. 10 is a schematic plan view showing an outline of the mechanical quantity measuring device according to the second embodiment. Also in FIG. 10, in order to simplify the drawing, details of wiring (for example, wiring to each impurity diffusion resistor) are omitted.

  As shown in FIG. 10, the mechanical quantity measuring device 30 ′ according to the second embodiment is configured such that the Wheatstone bridge A ′ of FIG. 8 and the Wheatstone bridge B ′ of FIG. They are arranged concentrically. Each of the Wheatstone bridges A ′ and B ′ is connected to the power supply terminal 4 and the ground terminal 5. The signal obtained from the Wheatstone bridge A ′ (potential difference in the bridge voltage) is amplified by the amplifier circuit 6 formed in the silicon single crystal substrate 1, and the signal obtained from the Wheatstone bridge B ′ is formed in the silicon single crystal substrate 1. Amplified by the amplifier circuit 31. The signal amplified by the amplifier circuit 6 and the signal amplified by the amplifier circuit 31 are input to the correction arithmetic circuit 32 formed in the silicon single crystal substrate 1, and the correction arithmetic circuit 32 uses the Wheatstone bridge A ′. A correction operation for calculating the true strain amount from the difference between the detected strain amount and the strain amount detected by the Wheatstone bridge B ′ is performed, and the signal subjected to the correction operation is taken out from the output terminal 7.

  In the mechanical quantity measuring device 30 ′, the Wheatstone bridge A ′ and the Wheatstone bridge B ′ are arranged so as to be in contact with each other without gaps (more precisely, the segments constituting the Wheatstone bridge A ′ and the Wheatstone bridge B ′ are configured. And the segment to be touched without any gap). In other words, the strain detection region is formed compactly. Thereby, the influence of creep deformation on the solder joint layer 22 can be suppressed as much as possible, and the accuracy of the correction calculation by the correction calculation circuit 32 is improved. Other functions and effects are the same as those of the mechanical quantity measuring device 30 of the first embodiment.

(Third embodiment of the present invention)
Here, the technical idea of the mechanical quantity measuring device according to the third embodiment of the present invention will be described with reference to FIGS. FIG. 11 is a schematic plan view showing the outline of the mechanical quantity measuring device according to the third embodiment. Also in FIG. 11, in order to simplify the drawing, details of wiring (for example, wiring to each impurity diffusion resistor) are omitted.

As shown in FIG. 11, the mechanical quantity measuring device 40 according to the third embodiment has three Wheatstone bridges A, B, and C arranged concentrically on the surface of the silicon single crystal substrate 1. doing. In other words, in the mechanical quantity measuring device 40, a third Wheatstone bridge C is disposed on the outer periphery of the Wheatstone bridge B of the mechanical quantity measuring device 30 of the first embodiment shown in FIG. The Wheatstone bridges A and B have the same configuration as those of the mechanical quantity measuring device 30, and the Wheatstone bridge C has four resistor groups RG _C1 and RG _C2 having a four-fold symmetrical shape about the concentric axis. , RG _C3 , RG _C4 .

Each of the four bridge resistors R _v1 , R _v2 , R _h1 , R _h2 constituting the Wheatstone bridge C is composed of an impurity diffusion resistor that is a multiple of the number of resistor groups (here, 4). Specifically, the bridge resistor R _v1 consists of four diffusion resistors _{r Cv11, r Cv12, r Cv13} , r Cv14, bridge resistors R _v2 impurity diffused resistor _{r Cv21, r Cv22, r Cv23} , r consists of four _Cv24, bridge resistors R _h1 consists of four diffusion resistors _{r Ch11, r Ch12, r Ch13} , r Ch14, bridge resistors R _h2 are impurity diffused resistor r _Ch21, r _Ch22, r _Ch23 , R _Ch24 .

Further, each of the resistor groups constituting the Wheatstone bridge C has at least one impurity diffusion resistor constituting four bridge resistors. Specifically, the resistor group RG _C1 impurity diffused resistor _{r Cv11, r Ch11, r Cv21} , consists r _Ch21, resistor group RG _C2 impurity diffused resistor _{r Cv12, r Ch12, r Cv22} , r Ch22 consists, resistor group RG _C3 consists impurity diffusion resistor _{r Cv13, r Ch13, r Cv23} , r Ch23, resistor group RG _C4 consists impurity diffused resistor _{r Cv14, r Ch14, r Cv24} , r Ch24 .

  Each of the Wheatstone bridges A, B, and C is connected to a power supply terminal 4 and a ground terminal 5. A signal (potential difference in bridge voltage) obtained from the Wheatstone bridge A is amplified by an amplifier circuit 6 formed in the silicon single crystal substrate 1, and a signal obtained from the Wheatstone bridge B is an amplifier formed in the silicon single crystal substrate 1. A signal amplified by the circuit 31 and obtained from the Wheatstone bridge C is amplified by an amplifier circuit 41 formed in the silicon single crystal substrate 1. The signal amplified by the amplifier circuit 6, the signal amplified by the amplifier circuit 31, and the signal amplified by the amplifier circuit 41 are input to the correction calculation circuit 32 formed in the silicon single crystal substrate 1, and the correction calculation is performed. In the circuit 32, a correction operation for calculating the true strain amount from the difference in strain amount detected in each of the Wheatstone bridges A, B, and C is performed, and the corrected signal is taken out from the output terminal 7.

  In the mechanical quantity measuring device 40, the correction calculation is performed using the strain amount detected in each of the triple Wheatstone bridges A, B, and C. Therefore, the accuracy of the correction calculation is improved compared to the mechanical quantity measuring device 30 (correction) Details of the calculation will be described later). Other functions and effects are the same as those of the mechanical quantity measuring device 30 of the first embodiment.

  Next, correction calculation will be described. FIG. 12 schematically shows the creep deformation distribution of the solder joint layer when the pseudo pressure sensor using the mechanical quantity measuring device according to the third embodiment is bending deformed, and the output voltage-strain diagram of each Wheatstone bridge. FIG.

Since the Wheatstone bridges A, B, and C are formed sufficiently small with respect to the size of the silicon single crystal substrate 1, the true strain amount generated in the Wheatstone bridges A, B, and C is considered to be essentially the same. However, as described above, creep deformation occurs in the solder joint layer 22 under a high temperature environment, and the amount of creep deformation increases toward the outer peripheral region of the mechanical quantity measuring device 40. That is, as shown in FIG. 12, e than Wheatstone bridge creep deformation amount of strain detection areas A epsilon _A, Wheatstone bridge it is large creep deformation amount epsilon _B strain detection area B, Wheatstone bridge B strain detection than the creep deformation amount epsilon _B region, it is larger in the Wheatstone bridge C of creep deformation amount of the strain detection region _{ε C (ε a <ε B} <ε C).

Since the stress relaxation occurs as the creep deformation amount increases, the strain amount propagated to the Wheatstone bridges A, B, and C decreases more than the true strain amount (the strain amount in an ideal state without creep deformation). As a result, the output voltages Y _A , Y _B , Y _C of the Wheatstone bridges A, B, C are lower than the ideal output voltage Y _i , and the output voltages Y _A , Y of the Wheatstone bridges A, B, C are reduced. _B, and a difference between the Y _C occurs. Further, the difference between the output voltages Y _A , Y _B , and Y _C is considered to be proportional to the difference in creep deformation amount in the region where the Wheatstone bridges A, B, and C are formed.

As in the first embodiment, the output voltage at zero strain in the ideal state is V _i0 , the output voltage at zero strain of Wheatstone bridge A is V _A0, and the output voltage at zero strain of Wheatstone bridge B is _Assuming V _B0 , the output voltage of the Wheatstone bridge C at zero strain is V _C0 , the true strain is X, and the strain sensitivity of the Wheatstone bridge is G, Y _i , Y _A , Y _B It is expressed as 1) to (3), and Y _C can be expressed as in the following formula (7).
Y _i = V _i0 + GX Equation (1),
Y _A = V _A0 + GX Equation (2),
Y _B = V _B0 + GX Equation (3),
Y _C = V _C0 + GX Equation (7).

The difference between Y _A and Y _B and the difference between Y _A and Y _C can be expressed by the following equations (4) and (8) from equations (2), (3), and (7).
Y _A − Y _B = V _A0 − V _B0 Equation (4),
Y _A −Y _C = V _A0 −V _C0 (8)

Similarly to the first embodiment, the creep deformation distribution (relationship between the creep deformation amount and the position) of the solder joint layer 22 in the region where the Wheatstone bridges A, B, and C are formed (strain detection region) is It can be approximated by a linear function substantially. Note that the distance between the concentric Wheatstone bridges A, B, and C and the Wheatstone bridge C is L _C, and the distance between the Wheatstone bridges A and C is L _AC . The distance L _C is defined as the average distance between the region where the Wheatstone bridge C is formed and the center of the Wheatstone bridge C, and the distance L _AC is defined as the difference between L _A and L _C.

The difference between the output voltage V _i0 and the output voltage V _A0 is the distance L _A between the concentricity and the Wheatstone bridge A, the distance L _AC between the Wheatstone bridges A and C, and the equation (8) in addition to the above equation (5). ) Can also be expressed as in the following formula (9).
V _i0 − V _A0 = (V _A0 − V _B0 ) • L _A / L _AB = (Y _A − Y _B ) • L _A / L _AB ... Equation (5),
V _i0 −V _A0 = (V _A0 −V _C0 ) · L _A / L _AC = (Y _A −Y _C ) · L _A / L _AC (9)

The above-described equation (6) is obtained from the equations (1), (2), and (5), and the following equation (10) is obtained from the equations (1), (8), and (9).
_{Y i = Y A + (V} i0 - V A0) = Y A + (Y A - Y B) · L A / L AB ··· Equation (6),
Y _i = Y _A + (V _i0 −V _C0 ) = Y _A + (Y _A −Y _C ) · L _A / L _AC (Equation 10)

In the equations (6) and (10), the output voltages Y _A , Y _B and Y _C are obtained as measured values from the Wheatstone bridges A, B and C, and the distances L _A , L _AB and L _AC are the Wheatstone bridges. Since the values are obtained from the dimensions of A, B, and C, the output voltage Y _i in the ideal state can be obtained from each equation. That is, the mechanical quantity measuring device 40 of the present embodiment can calculate the output voltage Y _i from the combination of the Wheatstone bridges A and C in addition to the combination of the Wheatstone bridges A and B. The Wheatstone bridge A, the output voltage was calculated from the combination of B Y _i and Wheatstone bridge A, by comparing the output voltage Y _i calculated from the combination of C, and the like accuracy of existence and the correction value of the creep occurs It can be verified, and more accurate correction calculation is possible.

In the mechanical quantity measuring device 40 of the present embodiment, since the strain detection region is composed of triple Wheatstone bridges A, B, and C, in addition to the above-described linear function approximation of the creep deformation quantity distribution, the creep deformation quantity distribution is quadratic. Even when function approximation is performed, correction calculation can be performed with high accuracy. For example, the difference between the output voltage V _i0 and the output voltage V _A0 can be expressed as the following equations (11) and (12).
V _i0 − V _A0 = (V _A0 − V _B0 ) · L _A ² / (L _B ² − L _A ² ) Equation (11),
V _i0 −V _A0 = (V _A0 −V _C0 ) · L _A ² / (L _C ² −L _A ² ) (12)

From the formulas (1), (2), (8), (11), and (12), the following formulas (13) and (14) are obtained.
Y _i = Y _A + (V _i0 − V _A0 ) = Y _A + (Y _A − Y _B ) · L _A ² / (L _B ² − L _A ² ) ・ ・ ・ Equation (13), Y _i = Y _{A + (V i0 - V C0} ) = Y A + (Y A - Y C) · L A 2 / (L C 2 - L A 2) ··· equation (14).

Creep deformation is obtained by comparing the output voltage Y _i calculated from the combination of the Wheatstone bridges A and B with the output voltage Y _i calculated from the combination of the Wheatstone bridges A and C using the equations (13) and (14). The accuracy of the correction value and the correction value can be verified, and more accurate correction calculation can be performed.

(Fourth embodiment of the present invention)
Here, a more specific example of the above-described third embodiment will be described with reference to FIGS. FIG. 13 is a schematic plan view and a wiring system diagram showing an example of a Wheatstone bridge other than the innermost circumference in the mechanical quantity measuring device of the fourth embodiment. In the schematic plan view of FIG. 13, details of wiring (for example, wiring between impurity diffusion resistors) are omitted in order to simplify the drawing.

As shown in FIG. 13, the Wheatstone bridge C ′ other than the innermost circumference in the present embodiment is composed of four resistor groups RG _C1 , RG _C2 , RG _C3 , RG _C4 having a four-fold symmetrical shape, Each of the resistor groups has a structure in which a plurality of segments 33 are arranged in series. Similar to the Wheatstone bridges A ′ and B ′ described above, the segment 33 includes a plurality of impurity diffusion resistors having a linear shape. In the segment 33, the plurality of impurity diffusion resistors are arranged so that their linear directions are parallel to each other, and the segment 33 has a rectangular shape.

Each of the four bridge resistors R _v1 , R _v2 , R _h1 , R _h2 constituting the Wheatstone bridge C ′ is composed of an impurity diffusion resistor that is a multiple of the number of resistor groups (here, 4). Specifically, the bridge resistance R _v1 is composed of 20 impurity diffusion resistors r _Cv11 , r _Cv12 , r _Cv13 , r _Cv14 ,..., R _Cv117 , r _Cv118 , r _Cv119 , r _Cv120 , and the bridge resistance R _v2 is composed of 20 impurity diffusion resistors r _Cv21 , r _Cv22 , r _Cv23 , r _Cv24 ,..., r _Cv217 , r _Cv218 , r _Cv219 , r _Cv220 , and the bridge resistor R _h1 is an impurity diffusion resistor r _Ch11. , R _Ch12 , r _Ch13 , r _Ch14 ,..., R _Ch117 , r _Ch118 , r _Ch119 , r _Ch120 , and the bridge resistance R _h2 is an impurity diffusion resistor r _Ch21 , r _Ch22 , r _Ch23 , r _.. , _RCh217 , _rCh218 , _rCh219 , _rCh220 .

Similarly to the Wheatstone bridge B ′ described above, the adjacent segments 33 in the resistor groups RG _{C1 to} RG _C4 are arranged so that the line directions of the impurity diffusion resistors constituting the segments 33 are orthogonal to each other. It is arranged. For example, one segment 33 in the resistor group RG _C1 is a direction in which the line direction of the impurity diffusion resistors r _Cv11 , r _Cv12 , r _Cv21 , r _Cv22 is orthogonal to the <1 1 0> direction of the silicon single crystal substrate 1 The impurity diffusion resistors are connected so that a current flows in that direction. Segment 33 adjacent thereto in the resistor group RG inside _C1, an impurity diffusion resistor _{r Ch11, r Ch12, r Ch21} , linear direction of r _{CH 22} is a silicon single crystal substrate 1 <1 1 0> as in a direction The impurity diffusion resistors are arranged and connected so that a current flows in that direction. Further, the segment 33 adjacent thereto is _{arranged so that} the line direction of the impurity diffusion resistors r _Cv13 , r _Cv14 , r _Cv23 , r _Cv24 is perpendicular to the <1 1 0> direction of the silicon single crystal substrate 1. The impurity diffusion resistors are connected so that a current flows in that direction.

As can be seen from FIG. 13 and the above description, each of the resistor groups RG _{C1 to} RG _C4 has all four bridge resistance elements. From this, the Wheatstone bridge C ′ has a high in-plane detection isotropic property in its own strain detection region (in the region where the impurity diffusion resistor constituting the Wheatstone bridge is formed). The characteristic is that an averaged signal can be obtained.

  Further, the segment 33 of the Wheatstone bridge C ′ preferably has a dummy resistor 34 which is the same in structure as the impurity diffusion resistor but is not electrically connected, like the Wheatstone bridges A ′ and B ′.

  FIG. 14 is a schematic plan view illustrating an outline of the mechanical quantity measuring device according to the fourth embodiment. Also in FIG. 14, in order to simplify the drawing, details of wiring (for example, wiring to each impurity diffusion resistor) are omitted.

  As shown in FIG. 14, the mechanical quantity measuring device 40 ′ according to the fourth embodiment includes a Wheatstone bridge A ′ (see FIG. 8) and a Wheatstone bridge B ′ (see FIG. 9) on the surface of the silicon single crystal substrate 1. ) And the Wheatstone bridge C ′ (see FIG. 13) are arranged concentrically with each other. Each of the Wheatstone bridges A ′, B ′, and C ′ is connected to the power supply terminal 4 and the ground terminal 5. The signal obtained from the Wheatstone bridge A ′ (potential difference in the bridge voltage) is amplified by the amplifier circuit 6 formed in the silicon single crystal substrate 1, and the signal obtained from the Wheatstone bridge B ′ is formed in the silicon single crystal substrate 1. The signal amplified by the amplifier circuit 31 and obtained from the Wheatstone bridge C ′ is amplified by the amplifier circuit 41 formed in the silicon single crystal substrate 1. The signal amplified by the amplifier circuit 6, the signal amplified by the amplifier circuit 31, and the signal amplified by the amplifier circuit 41 are input to the correction calculation circuit 32 formed in the silicon single crystal substrate 1, and the correction calculation is performed. In the circuit 32, a correction operation for calculating the true strain amount from the difference between the strain amount detected by the Wheatstone bridge A ′, the strain amount detected by the Wheatstone bridge B ′, and the strain amount detected by the Wheatstone bridge C ′ is performed. The signal that has been corrected and calculated is taken out from the output terminal 7.

  In the mechanical quantity measuring device 40 ', the Wheatstone bridge A', the Wheatstone bridge B ', and the Wheatstone bridge C' are arranged so as to contact each other without any gap. In other words, the strain detection region is formed compactly. Thereby, the influence of creep deformation on the solder joint layer 22 can be suppressed as much as possible, and the accuracy of the correction calculation by the correction calculation circuit 32 is improved. Other functions and effects are the same as those of the mechanical quantity measuring device 40 of the third embodiment.

(Fifth embodiment of the present invention)
Here, a modification of the above-described second embodiment will be described with reference to FIG. FIG. 15 is a schematic plan view illustrating the outline of the mechanical quantity measuring device according to the fifth embodiment. Also in FIG. 15, in order to simplify the drawing, details of wiring (for example, wiring to each impurity diffusion resistor) are omitted.

  As shown in FIG. 15, the mechanical quantity measuring device 50 according to the fifth embodiment includes a Wheatstone bridge A ′ (see FIG. 8) and a Wheatstone bridge C ′ (see FIG. 13) on the surface of the silicon single crystal substrate 1. Are arranged concentrically with each other. In short, the mechanical quantity measuring device 50 has a strain detection region in which the Wheatstone bridge B 'is removed from the previous mechanical quantity measuring device 40'.

  Each of the Wheatstone bridges A ′ and C ′ is connected to the power supply terminal 4 and the ground terminal 5. A signal (potential difference in bridge voltage) obtained from the Wheatstone bridge A ′ is amplified by an amplifier circuit 6 formed in the silicon single crystal substrate 1, and a signal obtained from the Wheatstone bridge C ′ is formed in the silicon single crystal substrate 1. Amplified by the amplifier circuit 41. The signal amplified by the amplifier circuit 6 and the signal amplified by the amplifier circuit 41 are input to the correction arithmetic circuit 32 formed in the silicon single crystal substrate 1, and the correction arithmetic circuit 32 uses the Wheatstone bridge A ′. A correction operation for calculating the true strain amount from the difference between the detected strain amount and the strain amount detected by the Wheatstone bridge C ′ is performed, and the signal subjected to the correction operation is taken out from the output terminal 7.

  In the mechanical quantity measuring device 50, since a gap is formed between the innermost Wheatstone bridge A ′ and the Wheatstone bridge C ′ other than the innermost circumference, each impurity diffusion constituting the Wheatstone bridge is arranged. The wiring of the resistor becomes easy and contributes to the improvement of manufacturing yield (that is, reduction of manufacturing cost). Further, since the Wheatstone bridge C ′ of the mechanical quantity measuring device 50 is disposed on the outer peripheral side than the Wheatstone bridge B ′ of the mechanical quantity measuring device 30 ′, the effect of creep deformation of the solder joint layer 22 is accelerated. Can be detected.

  The distance between the Wheatstone bridges arranged concentrically is preferably equal to or less than the length of one side of the segment 33 constituting the Wheatstone bridge. When the distance between the Wheatstone bridges is longer than the length of one side of the segment, the accuracy of the correction calculation is lowered. Other functions and effects are the same as those of the mechanical quantity measuring device 30 of the first embodiment.

(Sixth embodiment of the present invention)
Here, another modification of the second embodiment described above (modification of the fifth embodiment) will be described with reference to FIG. FIG. 16 is a schematic plan view illustrating the outline of the mechanical quantity measuring device according to the sixth embodiment. Also in FIG. 16, in order to simplify the drawing, details of wiring (for example, wiring to each impurity diffusion resistor) are omitted.

  As shown in FIG. 16, in the mechanical quantity measuring device 60 according to the sixth embodiment, the Wheatstone bridge A ′ (see FIG. 8) and the Wheatstone bridge C ″ are concentric with each other on the surface of the silicon single crystal substrate 1. In short, the Wheatstone bridge C ″ of the mechanical quantity measuring device 60 has a structure in which some segments are removed from the Wheatstone bridge C ′ in the previous mechanical quantity measuring device 50. .

  Each of the Wheatstone bridges A ′ and C ″ is connected to the power supply terminal 4 and the ground terminal 5. A signal (potential difference in bridge voltage) obtained from the Wheatstone bridge A ′ is formed in the silicon single crystal substrate 1. The signal amplified by the amplifier circuit 6 and obtained from the Wheatstone bridge C ″ is amplified by the amplifier circuit 41 formed in the silicon single crystal substrate 1. The signal amplified by the amplifier circuit 6 and the signal amplified by the amplifier circuit 41 are input to the correction arithmetic circuit 32 formed in the silicon single crystal substrate 1, and the correction arithmetic circuit 32 uses the Wheatstone bridge A ′. A correction operation for calculating the true strain amount from the difference between the detected strain amount and the strain amount detected by the Wheatstone bridge C ″ is performed, and the corrected signal is taken out from the output terminal 7.

  In the mechanical quantity measuring device 60, since the segment 33 constituting the Wheatstone bridge C '' is disposed with a gap, the wiring of each impurity diffusion resistor constituting the Wheatstone bridge is further facilitated, This contributes to an improvement in manufacturing yield (that is, a reduction in manufacturing cost).

  The distance between the segments 33 constituting one Wheatstone bridge is preferably equal to or less than the length of one side of the segment. If the distance between the segments 33 within one Wheatstone bridge is longer than the length of one side of the segment, the in-plane isotropy of strain detection is lowered and the accuracy of the correction calculation is lowered. Other functions and effects are the same as those of the mechanical quantity measuring device 50 of the fifth embodiment.

(Seventh embodiment of the present invention)
Here, still another modification of the second embodiment described above (modification of the fifth embodiment) will be described with reference to FIG. FIG. 17 is a schematic plan view illustrating an outline of the mechanical quantity measuring device according to the seventh embodiment. Also in FIG. 17, in order to simplify the drawing, details of wiring (for example, wiring to each impurity diffusion resistor) are omitted.

  As shown in FIG. 17, in the mechanical quantity measuring device 70 according to the seventh embodiment, the Wheatstone bridge D and the Wheatstone bridge E are arranged concentrically on the surface of the silicon single crystal substrate 1. In short, the mechanical quantity measuring device 70 is an example in which the segments 33 are arranged so that the outer shape of the Wheatstone bridge is circular.

The innermost Wheatstone bridge D is composed of four resistor groups RG _D1 , RG _D2 , RG _D3 , and RG _D4 having a four-fold symmetrical shape. Innermost circumference than the Wheatstone bridge E also has four resistors group to be four times symmetrical _{RG E1, RG E2, RG E3} , RG E4. Each resistor group has a structure in which a plurality of segments 33 are arranged in series. Since the configuration of each segment 33 is the same as that of the fifth embodiment described above, detailed description is omitted, but each resistor group includes at least one impurity diffusion resistor constituting the four bridge resistors of the Wheatstone bridge. Have one by one.

  Each of the Wheatstone bridges D and E is connected to the power supply terminal 4 and the ground terminal 5. A signal (potential difference in the bridge voltage) obtained from the Wheatstone bridge D is amplified by an amplifier circuit 71 formed in the silicon single crystal substrate 1, and a signal obtained from the Wheatstone bridge E is an amplifier formed in the silicon single crystal substrate 1. Amplified by circuit 72. The signal amplified by the amplifier circuit 71 and the signal amplified by the amplifier circuit 72 are input to the correction arithmetic circuit 32 formed in the silicon single crystal substrate 1, and detected by the Wheatstone bridge D in the correction arithmetic circuit 32. The correction calculation for calculating the true strain amount is performed from the difference between the strain amount to be detected and the strain amount detected by the Wheatstone bridge E, and the signal subjected to the correction calculation is taken out from the output terminal 7.

  The mechanical quantity measuring device 70 has an advantage that the in-plane isotropy of strain detection is further improved because the segment 33 is arranged so that the outer shape of the Wheatstone bridge is circular. Other functions and effects are the same as those of the mechanical quantity measuring device 50 of the fifth embodiment.

(Eighth embodiment of the present invention)
Here, the pressure sensor according to the present invention will be described with reference to FIG. The pressure sensor according to the present invention is characterized in that the mechanical quantity measuring device according to the present invention is used as a strain sensor. FIG. 18 is a schematic cross-sectional view showing an example of a pressure sensor according to the present invention.

  As shown in FIG. 18, the pressure sensor 80 according to the present invention is roughly divided into a sensor unit that receives pressure and converts it into an electrical signal, and a connector unit that transmits the electrical signal to an external device. The sensor part is a metal bottomed cylindrical body with one end opened and the other end closed, a pressure introduction part 81 inserted into the pressure port, a flange 82 that defines the amount of insertion of the pressure introduction part 81, and a pressure introduction The diaphragm 83 is deformed by receiving pressure on the closed end side of the part 81, a strain sensor 84 soldered on the diaphragm 83, and a control mechanism 85 connected to the strain sensor 84 and controlling the strain sensor 84. The control mechanism 85 is equipped with a memory storing various data used for correction calculation, a capacitor 86, and the like. The connector portion includes a connector 87 connected to an external device, a connection terminal 88 that transmits an electrical signal, and a cover 89 that fixes the connector 87 to the sensor portion.

  Since the pressure sensor 80 uses the mechanical quantity measuring device according to the present invention as the strain sensor 84, higher accuracy and long-term reliability can be ensured even when used in a high-temperature and high-pressure environment.

  Note that the above-described embodiment has been described in order to help understanding of the present invention, and the present invention is not limited to the specific configuration described. For example, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. That is, according to the present invention, a part of the configuration of the embodiment of the present specification can be deleted, replaced with another configuration, or added with another configuration.

10 ... Semiconductor strain sensor,
1 ... Silicon single crystal substrate, 2 ... Impurity diffusion resistor, 3 ... Wheatstone bridge,
4 ... Power supply terminal, 5 ... Ground terminal, 6 ... Amplifier circuit, 7 ... Output terminal,
20 ... Pseudo pressure sensor, 21 ... Metal plate, 22 ... Solder joint layer, 23 ... Terminal block,
30, 30 '... mechanical quantity measuring device, 31 ... amplifier circuit, 32 ... correction arithmetic circuit,
33 ... segment, 34 ... dummy resistor,
40, 40 '... Mechanical quantity measuring device, 41 ... Amplifier circuit,
50, 60, 70 ... mechanical quantity measuring device, 71, 72 ... amplifier circuit,
80 ... Pressure sensor, 81 ... Pressure introduction part, 82 ... Flange, 83 ... Diaphragm,
84 ... Strain sensor, 85 ... Control mechanism, 86 ... Capacitor,
87 ... Connector, 88 ... Connection terminal, 89 ... Cover.

Claims (10)

A mechanical quantity measuring device having a strain detection region constituted by an impurity diffusion resistor formed on the surface of a semiconductor substrate,
The strain detection region has a plurality of Wheatstone bridges arranged concentrically with each other,
The innermost Wheatstone bridge among the plurality of Wheatstone bridges is composed of two resistor groups having a two-fold symmetry around the concentric axis or four resistor groups having a four-fold symmetry shape ,
Each of the four bridge resistors constituting the Wheatstone bridge is composed of the impurity diffusion resistors that are multiples of the number of the resistor groups of the Wheatstone bridge, and each of the resistor groups has the four bridge resistances. Having at least one impurity diffusion resistor to constitute,
A correction operation circuit for performing a correction calculation of a strain amount based on the output from each of the plurality of Wheatstone bridges is further provided on the semiconductor substrate, and the correction calculation is performed by the output from the plurality of Wheatstone bridges. In addition, the vehicle control device is performed based on the distance from the concentricity of each of the plurality of Wheatstone bridges. The mechanical quantity measuring device according to claim 1,
Each of the impurity diffusion resistors has a linear shape,
The resistor group has a structure arranged such that a plurality of segments are connected,
The segment is composed of a plurality of the impurity diffusion resistors in which the linear directions of the impurity diffusion resistors are arranged in parallel to each other, and the segment has a rectangular shape, characterized in that The mechanical quantity measuring device according to claim 1 ,
The segments adjacent to each other in the resistor group are arranged so that the linear directions of the impurity diffusion resistors constituting the segments are orthogonal to each other. In the mechanical quantity measuring device according to claim 2 or claim 3 ,
The distance between the plurality of Wheatstone bridges is equal to or less than the length of one side of the segment. In the mechanical quantity measuring device according to any one of claims 2 to 4 ,
The mechanical quantity measuring apparatus according to claim 1, wherein a distance between the adjacent segments in the Wheatstone bridge is equal to or less than a length of one side of the segment. In the mechanical quantity measuring device according to any one of claims 2 to 5 ,
The segment quantity device has a dummy resistor which has the same configuration as the impurity diffusion resistor but is not electrically connected. The mechanical quantity measuring device according to any one of claims 1 to 6 ,
The semiconductor substrate is a silicon single crystal substrate,
The impurity diffusion resistor is connected so that a direction of current flowing through the impurity diffusion resistor is a <1 1 0> direction of the silicon single crystal substrate or a direction orthogonal to the <1 1 0> direction. Mechanical quantity measuring device. A pressure sensor in which a semiconductor strain sensor is joined on a metal diaphragm,
The semiconductor strain sensor, a pressure sensor, which is a mechanical-quantity measuring device according to any one of claims 1 to 7. The pressure sensor according to claim 8 .
The pressure sensor according to claim 1, wherein the bonding is a solder bonding. The pressure sensor according to claim 8 or 9 ,
The pressure sensor is a pressure sensor for an automobile engine.

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