阅读说明：本技术 传感器装置 (Sensor device ) 是由 工藤康博 于 2020-01-13 设计创作，主要内容包括：本发明提供一种传感器装置,其目的在于抑制泄漏电流的产生。该传感器装置具备形成在半导体基板内且具有与上述半导体基板相反的极性的压阻元件、形成在上述半导体基板内且具有与上述半导体基板相反的极性的扩散配线、形成于上述半导体基板内的相邻的上述扩散配线之间且具有与上述半导体基板相同的极性的第一屏蔽层、形成于上述压阻元件与上述扩散配线的表层且具有与上述第一屏蔽层相同的极性的第二屏蔽层。(The invention provides a sensor device, which aims to restrain the generation of leakage current. The sensor device includes a piezoresistive element formed in a semiconductor substrate and having a polarity opposite to that of the semiconductor substrate, diffusion wires formed in the semiconductor substrate and having a polarity opposite to that of the semiconductor substrate, a first shield layer formed between adjacent diffusion wires in the semiconductor substrate and having a polarity identical to that of the semiconductor substrate, and a second shield layer formed on a surface layer of the piezoresistive element and the diffusion wires and having a polarity identical to that of the first shield layer.)

1. A sensor device, characterized in that,

comprising:

a piezoresistive element formed in a semiconductor substrate and having a polarity opposite to that of the semiconductor substrate;

a diffusion wiring formed in the semiconductor substrate and having a polarity opposite to that of the semiconductor substrate;

a first shield layer formed between adjacent diffusion wirings in the semiconductor substrate and having the same polarity as the semiconductor substrate; and

and a second shield layer formed on the surface layers of the piezoresistive element and the diffusion wire and having the same polarity as the first shield layer.

2. The sensor device of claim 1,

the first shielding layer is also formed between adjacent piezoresistive elements.

3. The sensor device according to claim 1 or 2,

the first shield layer has a higher impurity concentration than the semiconductor substrate, and the second shield layer has a higher impurity concentration than the first shield layer.

4. The sensor device of claim 3,

the diffusion wiring has a higher impurity concentration than the piezoresistive element.

5. The sensor device according to claim 1 or 2,

the semiconductor substrate has a wiring formed with an insulating film interposed therebetween, and the wiring is connected to the diffusion wiring with a contact plug penetrating the insulating film interposed therebetween.

6. The sensor device of claim 5,

the semiconductor device includes an electrode pad for pull-up formed on the insulating film, and the electrode pad is connected to the first shield layer through a contact plug penetrating the insulating film.

7. The sensor device of claim 6,

the polarity of the semiconductor substrate is n-type.

8. The sensor device according to claim 1 or 2,

the forces in the multiaxial direction and/or the moments of the forces can be detected.

Technical Field

The present invention relates to a sensor device, and more particularly, to a pressure sensor for detecting a force in a multi-axis direction.

Background

Conventionally, there is known a pressure sensor that detects a force in multiple axes by mounting a sensor element in a strain body formed of a metal and detecting an elastic deformation of the strain body generated by applying an external force with the sensor element.

In the pressure sensor, a sensor chip manufactured using a semiconductor substrate such as an soi (silicon On insulator) substrate is used as a sensor element (see, for example, patent documents 1 and 2). A piezoresistive/diffusion wiring layer as a strain detection element is formed in a semiconductor substrate constituting a sensor chip, and a metal wiring layer is formed on the semiconductor substrate.

Disclosure of Invention

In view of the above, the disclosed technology aims to suppress the generation of leakage current.

The disclosed technology is a sensor device including a piezoresistive element formed in a semiconductor substrate and having a polarity opposite to that of the semiconductor substrate, diffusion wires formed in the semiconductor substrate and having a polarity opposite to that of the semiconductor substrate, a first shield layer formed between adjacent diffusion wires in the semiconductor substrate and having a polarity identical to that of the semiconductor substrate, and a second shield layer formed on a surface layer of the piezoresistive element and the diffusion wires and having a polarity identical to that of the first shield layer.

The effects of the present invention are as follows.

According to the disclosed technology, generation of leakage current can be suppressed.

Drawings

Fig. 1 is a view of the sensor chip of the first embodiment as viewed from the upper side in the Z-axis direction.

Fig. 2 is a view of the sensor chip of the first embodiment as viewed from the lower side in the Z-axis direction.

Fig. 3 is a diagram illustrating symbols representing forces and moments applied to respective axes.

Fig. 4 is a diagram illustrating the configuration of the piezoresistive elements of the sensor chip.

Fig. 5 is a diagram illustrating an electrode arrangement and wiring in the sensor chip.

Fig. 6 is a diagram illustrating the layout of the electrode pads and the wirings in the region of the supporting portion in fig. 5.

Fig. 7 is a diagram illustrating the layout of wiring in the region including the piezoresistive elements in fig. 5.

Fig. 8 is a cross-sectional view taken along line a-a in fig. 7.

Fig. 9 is a plan view showing a formation region of the first shield layer.

Fig. 10 is a plan view showing a formation region of the second shield layer.

Fig. 11 is a view schematically showing a cross section of a main part of the sensor chip.

In the figure: 15-electrode pad, 15 a-electrode pad, 15 b-contact plug, 16-wiring, 17-diffusion wiring, 18-contact plug, 18 c-contact, 19-first shield layer, 20-second shield layer, 110-sensor chip, 200-semiconductor substrate, 201-surface insulating film, 202-interlayer insulating film.

Detailed Description

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant description may be omitted.

< first embodiment >

(schematic structure)

Fig. 1 and 2 are schematic diagrams showing a sensor chip 110 as a sensor element used in the pressure sensor according to the first embodiment.

Fig. 1 is a view of the sensor chip 110 viewed from the upper side in the Z-axis direction, fig. 1(a) is a perspective view, and fig. 1(b) is a plan view. Fig. 2 is a view of the sensor chip 110 viewed from the lower side in the Z-axis direction, fig. 2(a) is a perspective view, and fig. 2(b) is a bottom view. A direction parallel to one side of the upper surface of the sensor chip 110 is an X-axis direction, a perpendicular direction is a Y-axis direction, and a thickness direction of the sensor chip 110 (a normal direction of the upper surface of the sensor chip 110) is a Z-axis direction. The X-axis direction, the Y-axis direction and the Z-axis direction are orthogonal to each other.

The sensor chip 110 is an mems (micro Electro Mechanical systems) sensor chip capable of detecting a force and/or a moment of the force in a direction of at most 6 axes with 1 chip, and is formed of a semiconductor substrate such as an SOI substrate. The planar shape of the sensor chip 110 is, for example, a square with an angle of about 3000 μm.

The sensor chip 110 includes 5 columnar support portions 111a to 111 e. The planar shape of the support portions 111a to 111e is, for example, a square with an angle of about 500 μm. The supporting portions 111a to 111d as the first supporting portions are arranged at four corners of the sensor chip 110. The support portion 111e as a second support portion is disposed at the center of the support portions 111a to 111 d.

The supporting portions 111a to 111e can be formed of, for example, an active layer, a BOX layer, and a support layer of an SOI substrate, and each thickness is, for example, about 500 μm.

A reinforcing beam 112a for reinforcing the structure is provided between the support portion 111a and the support portion 111b, with both ends thereof fixed to the support portion 111a and the support portion 111b (connecting adjacent support portions to each other). A reinforcing beam 112b for reinforcing the structure is provided between the support portion 111b and the support portion 111c, with both ends thereof fixed to the support portion 111b and the support portion 111c (connecting adjacent support portions to each other).

A reinforcing beam 112c for reinforcing the structure is provided between the support portion 111c and the support portion 111d, with both ends thereof fixed to the support portion 111c and the support portion 111d (connecting adjacent support portions to each other). A reinforcing beam 112d for reinforcing the structure is provided between the support portion 111d and the support portion 111a, with both ends thereof fixed to the support portion 111d and the support portion 111a (connecting adjacent support portions to each other).

In other words, the four reinforcing beams 112a, 112b, 112c, and 112d as the first reinforcing beams are formed in a frame shape, and corner portions that become intersections of the reinforcing beams are the supporting portions 111b, 111c, 111d, and 111 a.

The inner corner of the support portion 111a and the corner of the support portion 111e facing the inner corner are connected by a reinforcing beam 112e for reinforcing the structure. The inner corner of the support portion 111b and the corner of the support portion 111e facing the inner corner are connected by a reinforcing beam 112f for reinforcing the structure.

The inner corner of the support portion 111c and the corner of the support portion 111e facing the inner corner are connected by a reinforcing beam 112g for reinforcing the structure. The inner corner of the support portion 111d and the corner of the support portion 111e facing the inner corner are connected by a reinforcing beam 112h for reinforcing the structure. The reinforcing beams 112e to 112h as the second reinforcing beams are arranged obliquely with respect to the X-axis direction (Y-axis direction). That is, the reinforcing beams 112e to 112h are arranged non-parallel to the reinforcing beams 112a, 112b, 112c, and 112 d.

The reinforcing beams 112a to 112h can be formed of, for example, an active layer, a BOX layer, and a support layer of an SOI substrate. The thickness (width in the short-side direction) of the reinforcing beams 112a to 112h can be, for example, about 140 μm. The upper surfaces of the reinforcing beams 112a to 112h are substantially flush with the upper surfaces of the supporting portions 111a to 111 e.

In contrast, the lower surfaces of the reinforcing beams 112a to 112h are recessed by about 10 μm toward the upper surface side from the lower surfaces of the supporting portions 111a to 111e and the lower surfaces of the force points 114a to 114 d.

A detection beam 113a is provided inside the reinforcing beam 112a between the support portion 111a and the support portion 111b, and both ends of the detection beam 113a are fixed to the support portion 111a and the support portion 111b in parallel with the reinforcing beam 112a at a predetermined interval (the adjacent support portions are connected to each other) to detect skew.

A detection beam 113b is provided between the detection beam 113a and the support portion 111e, and the detection beam 113b is parallel to the detection beam 113a and the support portion 111e with a predetermined gap therebetween. The detection beam 113b connects the end of the reinforcing beam 112e on the support portion 111e side to the end of the reinforcing beam 112f on the support portion 111e side.

The substantially central portion in the longitudinal direction of the detection beam 113a and the substantially central portion in the longitudinal direction of the detection beam 113b facing the detection beam 113a are connected by a detection beam 113c disposed so as to be orthogonal to the detection beam 113a and the detection beam 113 b.

A detection beam 13d is provided inside the reinforcing beam 112b between the support portion 111b and the support portion 111c, and both ends of the detection beam 113d are fixed to the support portion 111b and the support portion 111c (connecting adjacent support portions to each other) in parallel with the reinforcing beam 112b at a predetermined interval therebetween, and are used for detecting skew.

The detection beam 113e is provided between the detection beam 113d and the support portion 111e in parallel with the detection beam 113d with a predetermined gap between the detection beam 113d and the support portion 111 e. The detection beam 113e connects the end of the reinforcing beam 112f on the side of the support portion 111e and the end of the reinforcing beam 112g on the side of the support portion 111 e.

The substantially central portion in the longitudinal direction of the detection beam 113d and the substantially central portion in the longitudinal direction of the detection beam 113e facing the detection beam 113d are connected by a detection beam 113f disposed so as to be orthogonal to the detection beam 113d and the detection beam 113 e.

A detection beam 113g is provided inside the reinforcing beam 112c between the support portion 111c and the support portion 111d, and both ends of the detection beam 113g are fixed to the support portion 111c and the support portion 111d (to connect adjacent support portions to each other) in parallel with the reinforcing beam 112c at a predetermined interval therebetween to detect skew.

A detection beam 113h is provided between the detection beam 113g and the support 111e, parallel to the detection beam 113g, at a predetermined interval from the detection beam 113g and the support 111 e. The detection beam 113h connects the end of the reinforcing beam 112g on the side of the support portion 111e and the end of the reinforcing beam 112h on the side of the support portion 111 e.

The substantially central portion in the longitudinal direction of the detection beam 113g and the substantially central portion in the longitudinal direction of the detection beam 113h opposed thereto are connected by a detection beam 113i disposed so as to be orthogonal to the detection beam 113g and the detection beam 113 h.

A detection beam 113j is provided inside the reinforcing beam 112d between the support portion 111d and the support portion 111a, and both ends of the detection beam 113j are fixed to the support portion 111d and the support portion 111a (connecting adjacent support portions to each other) in parallel with the reinforcing beam 112d at a predetermined interval therebetween to detect skew.

The detection beam 113k is provided between the detection beam 113j and the support 111e, parallel to the detection beam 113j, with a predetermined gap between the detection beam 113j and the support 111 e. The detection beam 113k connects the end of the reinforcing beam 112h on the support portion 111e side and the end of the reinforcing beam 112e on the support portion 111e side.

The substantially central portion in the longitudinal direction of the detection beam 113j and the substantially central portion in the longitudinal direction of the detection beam 113k facing the detection beam 113j are connected by a detection beam 113l disposed so as to be orthogonal to the detection beam 113j and the detection beam 113 k.

The detection beams 113a to 113l are provided on the upper end sides in the thickness direction of the support portions 111a to 111e, and may be formed of, for example, an active layer of an SOI substrate. The thickness (width in the short-side direction) of the detection beams 113a to 113l can be, for example, about 75 μm. The upper surfaces of the detection beams 113a to 113l are substantially flush with the upper surfaces of the support portions 111a to 111 e. The thickness of each of the detection beams 113a to 113l can be, for example, about 50 μm.

A force point 114a is provided on the lower surface side of the center portion in the longitudinal direction of the detection beam 113a (the intersection of the detection beam 113a and the detection beam 113 c). The detection beams 113a, 113b, and 113c and the force point 114a form a set of detection blocks.

The force point 114b is provided on the lower surface side of the center portion in the longitudinal direction of the detection beam 113d (the intersection of the detection beam 113d and the detection beam 113 f). The detection beams 113d, 113e, and 113f and the force point 114b form a set of detection blocks.

A force point 114c is provided on the lower surface side of the center portion in the longitudinal direction of the detection beam 113g (the intersection of the detection beam 113g and the detection beam 113 i). The detection beams 113g, 113h, and 113i and the force point 114c form a set of detection blocks.

A force point 114d is provided on the lower surface side of the center portion in the longitudinal direction of the detection beam 113j (the intersection of the detection beam 113j and the detection beam 113 l). The detection beams 113j, 113k, and 113l and the force point 114d form a set of detection blocks.

The force points 114a to 114d are positions where an external force is applied, and are formed of, for example, a BOX layer and a support layer of an SOI substrate. The lower surfaces of the force points 114a to 114d are substantially flush with the lower surfaces of the support portions 111a to 111 e.

By obtaining the forces from the four force points 114a to 114d or locating them in this way, the deformation of the beam is obtained which differs for each force, and therefore a sensor with good 6-axis separability can be realized.

In the sensor chip 110, the portion forming the inner corner is preferably R-shaped from the viewpoint of suppressing stress concentration.

Fig. 3 is a diagram illustrating symbols representing forces and moments applied to respective axes. As shown in fig. 3, Fx, Fy, and Fz are forces in the Z-axis direction, the Y-axis direction, and the Z-axis direction, respectively. The moment of rotation about the X axis is Mx, the moment of rotation about the Y axis is My, and the moment of rotation about the Z axis is Mz.

Fig. 4 is a diagram illustrating the arrangement of the piezoresistive elements of the sensor chip 110. Piezoresistive elements are arranged at predetermined positions of the respective detection blocks corresponding to the four force points 114a to 114 d.

Specifically, in the detection block corresponding to the force point 114a, the piezoresistive elements MxR3 and MxR4 are disposed at positions on a line bisecting the detection beam 113a in the longitudinal direction and symmetrical with respect to a line bisecting the detection beam 113c in the longitudinal direction (Y direction) in a region of the detection beam 113a close to the detection beam 113 c. The piezoresistive elements FyR3 and FyR4 are disposed at positions that are closer to the reinforcing beam 112a than a line that bisects the detection beam 113a in the longitudinal direction and that are symmetrical with respect to a line that bisects the detection beam 113c in the longitudinal direction in a region of the detection beam 113a that is farther from the detection beam 113 c.

In the detection block corresponding to the force point 114b, the piezoresistive elements MyR3 and MyR4 are disposed at positions that are on a line that bisects the detection beam 113d in the longitudinal direction and that are symmetrical with respect to a line that bisects the detection beam 113f in the longitudinal direction (Y direction) in a region of the detection beam 113d that is close to the detection beam 113 f. The piezoresistive elements FxR3 and FxR4 are disposed at positions that are closer to the reinforcing beam 112b side than a line that bisects the detection beam 113d in the longitudinal direction and that are symmetrical with respect to a line that bisects the detection beam 113f in the longitudinal direction in a region of the detection beam 113d that is farther from the detection beam 113 f.

The piezoresistive elements MzR3 and MzR4 are disposed at positions on a line that bisects the detection beam 113d in the longitudinal direction and that are symmetrical with respect to a line that bisects the detection beam 113f in the longitudinal direction in a region of the detection beam 113d that is distant from the detection beam 113 f. The piezoresistive elements FzR2 and FzR3 are disposed on the support portion 111e side with respect to the line bisecting the detection beam 113e in the longitudinal direction and at positions symmetrical to the line bisecting the detection beam 113f in the longitudinal direction in the region of the detection beam 113e close to the detection beam 113 f.

In the detection block corresponding to the force point 114c, the piezoresistive elements MxR1 and MxR2 are disposed at positions that are on a line that bisects the detection beam 113g in the longitudinal direction and are symmetrical with respect to a line that bisects the detection beam 113i in the longitudinal direction (Y direction) in a region of the detection beam 113g that is close to the detection beam 113 i. The piezoresistive elements FyR1 and FyR2 are disposed on the reinforcing beam 112c side with respect to the line bisecting the detection beam 113g in the longitudinal direction, and at positions symmetrical to the line bisecting the detection beam 113i in the longitudinal direction in the region of the detection beam 113g away from the detection beam 113 i.

In the detection block corresponding to the force point 114d, the piezoresistive elements MyR1 and MyR2 are disposed at positions that are on a line that bisects the detection beam 113j in the longitudinal direction and that are symmetrical with respect to a line that bisects the detection beam 113l in the longitudinal direction (X direction) in a region of the detection beam 113j that is close to the detection beam 113 l. The piezoresistive elements FxR1 and FxR2 are disposed on the reinforcing beam 112d side with respect to the line bisecting the detection beam 113j in the longitudinal direction, and at positions symmetrical to the line bisecting the detection beam 113l in the longitudinal direction in the region of the detection beam 113j distant from the detection beam 113 l.

The piezoresistive elements MzR1 and MzR2 are disposed at positions on a line bisecting the detection beam 113j in the longitudinal direction and symmetrical to the line bisecting the detection beam 113l in the longitudinal direction in a region of the detection beam 113j distant from the detection beam 113 l. The piezoresistive elements FzR1 and FzR4 are disposed on the support portion 111e side with respect to the line bisecting the detection beam 113k in the longitudinal direction and at positions symmetrical to the line bisecting the detection beam 113l in the longitudinal direction in the region of the detection beam 113k close to the detection beam 113 l.

In this manner, in the sensor chip 110, a plurality of piezoresistive elements are separately arranged in each detection block. Accordingly, a predetermined axial displacement of 6 axes at most can be detected based on a change in the output of the plurality of piezoresistive elements arranged on a predetermined beam in accordance with the direction (axial direction) of the force applied (transmitted) to the force points 114a to 114 d.

In the sensor chip 110, the detection beams 113c, 113f, 113i, and 113l are made as short as possible, the detection beams 113b, 113e, 113h, and 113k are made to approach the detection beams 113a, 113d, 113g, and 113j, and the lengths of the detection beams 113b, 113e, 113h, and 113k are secured as long as possible. With this configuration, the detection beams 113b, 113e, 113h, and 113k are easily bent in a bow shape, and stress concentration can be alleviated, thereby improving the load-bearing capacity.

In the sensor chip 110, the piezoresistive elements are not arranged on the detection beams 113c, 113f, 113i, and 113l, which are shortened and thus have reduced deformation with respect to stress. Instead, the piezoresistive elements are arranged in the vicinity of the positions where the stress of the detection beams 113a, 113d, 113g, and 113j and the detection beams 113b, 113e, 113h, and 113k, which are thinner and longer than the detection beams 113c, 113f, 113i, and 113l and are easily bent in a bow shape, is maximum. As a result, the sensor chip 110 can efficiently detect stress and improve sensitivity (change in resistance of the piezoresistive element with respect to the same stress).

In the sensor chip 110, a dummy piezoresistive element is arranged in addition to the piezoresistive element for detecting skew. The dummy piezoresistive elements are arranged such that all the piezoresistive elements including the piezoresistive element for detecting skew are point-symmetric with respect to the center of the support portion 111 e.

Here, the piezoresistive elements FxR1 through FxR4 detect the force Fx, the piezoresistive elements FyR1 through FyR4 detect the force Fy, and the piezoresistive elements FzR1 through FzR4 detect the force Fz. The piezoresistive elements MxR1 to MxR4 detect the moment Mx, the piezoresistive elements MyR1 to MyR4 detect the moment My, and the piezoresistive elements MzR1 to MzR4 detect the moment Mz.

In this manner, in the sensor chip 110, a plurality of piezoresistive elements are separately arranged in each detection block. Accordingly, the displacement in the predetermined axial direction of the 6 axes at the maximum can be detected based on the change in the output of the plurality of piezoresistive elements arranged on the predetermined beam in the direction (axial direction) in which the force or displacement is applied (transmitted) to the force points 114a to 114 d.

Specifically, in the sensor chip 110, the displacement (Mx, My, Fz) in the Z-axis direction can be detected based on the deformation of a predetermined detection beam. That is, the moments (Mx, My) in the X-axis direction and the Y-axis direction can be detected based on the deformation of the detection beams 113a, 113d, 113g, and 113j, which are the first detection beams. The force (Fz) in the Z-axis direction can be detected based on the deformation of the detection beams 113e and 113k as the second detection beams.

In the sensor chip 110, displacements (Fx, Fy, and Mz) in the X-axis direction and the Y-axis direction can be detected based on a predetermined deformation of the detection beam. That is, the forces (Fx, Fy) in the X-axis direction and the Y-axis direction can be detected based on the deformation of the detection beams 113a, 113d, 113g, and 113j as the first detection beams. The moment (Mz) in the Z-axis direction can be detected based on the deformation of the detection beams 113d and 113j, which are the first detection beams.

In the sensor chip 110, the output of each axis can be obtained from a bridge circuit formed on each axis.

However, in order to reduce the number of piezoresistive elements, a displacement sensor chip for detecting a predetermined axial direction of 5 or less axes may be used.

Fig. 5 is a diagram illustrating an electrode arrangement and wiring in the sensor chip 110, and is a plan view of the sensor chip 110 as viewed from the upper side in the Z-axis direction. As shown in fig. 5, the sensor chip 110 has a plurality of electrode pads 15 for taking out power signals. Each electrode pad 15 is disposed on the upper surface of the support portions 111a to 111d of the sensor chip 110, which minimizes distortion when a force is applied to the force points 114a to 114 d. The wiring 16 from each piezoresistive element to the electrode pad 15 can be appropriately led back to each reinforcing beam and each detecting beam.

In this way, since each reinforcing beam is used as a bypass path when taking out the wiring as needed, the degree of freedom in wiring design can be increased by disposing the reinforcing beam differently from the detecting beam. Thus, each piezoresistive element can be arranged at a more desirable position.

The sensor chip 110 has an electrode pad 15a for pulling up the substrate potential by the power supply voltage.

Fig. 6 is a diagram illustrating the layout of the electrode pads and the wirings in the region 10 of the supporting portion 111b in fig. 5. The wiring 16 is a metal wiring made of aluminum or the like formed on the substrate. Each of the wires 16 is formed of the same layer, and a diffusion wire 17 is formed at a portion where the wires 16 intersect with each other by being led back to each portion. The diffusion wiring 17 is a wiring formed of a diffusion layer in the substrate, and is connected to the wiring 16 via a contact plug 18.

FIG. 7 is a diagram illustrating the layout of wiring in the region 11 including the piezoresistive elements MzR4, FxR4 in FIG. 5. The piezoresistive elements MzR4, FxR4 are formed between a pair of diffusion wires 17, respectively. The piezoresistive elements MzR4, FxR4 are diffusion regions having the same polarity as the diffusion wiring 17 and having a lower impurity concentration than the diffusion wiring 17. The diffusion wiring 17 is connected to the wiring 16 via a contact plug 18.

A first shield layer 19 formed of a diffusion region of opposite polarity to the diffusion wiring 17 and the piezoresistive elements MzR4 and FxR4 is formed around the diffusion wiring 17 and the piezoresistive elements MzR4 and FxR 4. That is, the first shield layer 19 is formed in a region other than the diffusion wiring 17 and the formation region 19a of the piezoresistive element.

The first shield layer 19 is formed between at least adjacent diffusion wirings 17 (except for the portion connecting the piezoresistive elements).

FIG. 8 is a cross-sectional view taken along line A-A in FIG. 7. As shown in FIG. 8, the sensor chip 110 is formed using a semiconductor substrate 200. in the case of forming the sensor chip 110 using an SOI substrate, the semiconductor substrate 200 is, for example, an active layer of the SOI substrate, the semiconductor substrate 200 is, for example, an n-type semiconductor substrate in which an n-type impurity is implanted into single-crystal silicon, and the impurity concentration of the semiconductor substrate 200 is, for example, 1.0 × 10^-15[m^-3]。

The diffusion wiring 17 is formed by implanting a p-type impurity into a predetermined region of the surface layer of the semiconductor substrate 200.

The first shield layer 19 is formed by implanting n-type impurities into a predetermined region of the surface layer of the semiconductor substrate 200. the impurity concentration of the first shield layer 19 is higher than that of the semiconductor substrate 200, and is, for example, 4.0 × 10^-15[m^-3]. The first shield layer 19 is formed so as to be spaced apart from the end of the diffusion wiring 17 by the spacing S1. The spacing S1 is, for example, 3.5 μm.

The piezoresistive element MzR4 is formed by implanting a p-type impurity into a predetermined region of the surface layer of the semiconductor substrate 200. The impurity concentration of the piezoresistive element MzR4 is lower than the impurity concentration of the diffusion wire 17. The other piezoresistive elements are also formed in the same manufacturing process as the piezoresistive element MzR 4.

A second shield layer 20 is formed on the surface layer of the semiconductor substrate 200. the second shield layer 20 is formed by implanting n-type impurities into a predetermined region of the surface layer of the semiconductor substrate 200. the second shield layer 20 is formed on a surface layer shallower than the diffusion wiring 17, the first shield layer 19, and the piezoresistive element.A concentration of impurities in the second shield layer 20 is higher than that of the first shield layer 19, and is, for example, 1.0 × 10^-13[m^-3]。

The second shield layer 20 is formed in a region excluding the formation region 18a (see fig. 7) of the contact plug 18. The second shield layer 20 is formed so as to be spaced apart from the end of the diffusion wire 17 by a distance S2. The spacing S2 is, for example, about 2 to 3 μm.

Silicon oxide (SiO) is formed on the semiconductor substrate 200₂) The surface insulating film 201 is formed. Further, silicon nitride (Si) is formed on the surface insulating film 201₃N₄) An interlayer insulating film 202 is formed.

The contact plug 18 is formed by filling a metal material into a through hole formed by etching the interlayer insulating film 202 and the surface insulating film 201.

The wiring 16 is formed by patterning a metal film formed of aluminum or the like formed on the interlayer insulating film 202. The electrode pad 15 is formed of the same metal film as the wiring 16.

The diffusion wiring 17, the first shield layer 19, the piezoresistive element, and the second shield layer 20 are formed on the semiconductor substrate 200 in this order. The first shield layer 19 is formed by ion-implanting n-type impurities at an acceleration voltage of 50KeV, for example. The depths of the first shield layer 19 and the second shield layer 20 are substantially constant.

Fig. 9 is a plan view showing a formation region of the first shield layer 19. The first shield layer 19 is formed substantially on the region excluding the diffusion fittings 17 and the formation regions 19a of the piezoresistive elements, but in the present embodiment, the formation regions 19b of the electrode pads 15 are also removed.

Fig. 10 is a plan view showing a formation region of the second shield layer 20. The second shield layer 20 is formed substantially on the region excluding the formation region 18a of the contact plug 18, but in the present embodiment, the formation region 18b of the electrode pad 15 is also removed. The second shield layer 20 is removed to connect the electrode pad 15a for pull-up to the contact portion 18c of the semiconductor substrate 200.

Fig. 11 is a diagram schematically showing a cross section of a main part of the sensor chip 110. As shown in fig. 11, the first shield layer 19 and the second shield layer 20 are not provided below the electrode pad 15. This is because the metal wire is connected to the electrode pad 15, and therefore, the influence of the stress at the time of bonding on the whole of the first shield layer 19 and the second shield layer 20 is suppressed. In the present embodiment, the first shield layer 19 and the second shield layer 20 are not provided below the electrode pad 15 in consideration of the influence of stress at the time of wire bonding, but when the influence of stress at the time of wire bonding on the first shield layer 19 and the second shield layer 20 can be ignored, either one or both of the first shield layer 19 and the second shield layer 20 may be provided below the electrode pad 15.

The second shield layer 20 is not provided below the contact plug 15b connected to the electrode pad 15a for pull-up, but the first shield layer 19 is provided. Therefore, the pull-up electrode pad 15a is connected to the first shield layer 19 through the contact plug 15b penetrating the interlayer insulating film 202 and the surface insulating film 201, and the potential of the first shield layer 19 is pulled up by the power supply voltage VDD.

(Effect)

In the sensor chip 110 of the present embodiment, the first shield layer 19 having a polarity opposite to that of the diffusion line 17 is formed on the adjacent diffusion line 17, so that the depletion layer D L is expanded by a reverse bias voltage to suppress generation of a leakage current, and similarly, in the sensor chip 110 of the present embodiment, the first shield layer 19 having a polarity opposite to that of the piezoresistive elements is formed between the adjacent piezoresistive elements, so that generation of a leakage current between the piezoresistive elements is suppressed.

In the sensor chip 110 of the present embodiment, since the second shield layer 20 having a polarity opposite to that of the diffusion wiring 17 and the piezoresistive element is formed on the surface layers of the diffusion wiring 17 and the piezoresistive element, the depletion layer D L is also formed between the diffusion wiring 17 and the piezoresistive element and the second shield layer 20, and the generation of leakage current between the wiring 16 and the diffusion wiring 17, and between the wiring 16 and the piezoresistive element can be suppressed.

By suppressing the generation of the leakage current, the compensation characteristic and the noise characteristic in the output of the sensor chip 110 are improved. The compensation characteristic is a characteristic of a compensation voltage of an output voltage from the bridge circuit. The occurrence of the leakage current causes variation in the compensation voltage according to the leakage current, and causes an error in the detection of the force and the moment. By suppressing the generation of the leakage current, the detection accuracy can be improved. In the sensor chip 110 capable of 6-axis detection, the output of force and moment in the Z-axis direction is small, and the sensor chip is easily affected by the leakage current, so that the improvement effect of suppressing the generation of the leakage current is large.

In the above embodiment, the semiconductor substrate 200, the first shield layer 19, and the second shield layer 20 are n-type, and the diffusion wiring 17 and the piezoresistive element are p-type, but on the contrary, the first shield layer 19 and the second shield layer 20 may be p-type, and the diffusion wiring 17 and the piezoresistive element may be n-type. The relationship of the impurity concentration of each layer is the same as described above.

While the preferred embodiments have been described in detail above, the present invention is not limited to the above embodiments, and various modifications and substitutions can be made to the above embodiments without departing from the scope of the present invention.