JP2002162411A - Semiconductor acceleration sensor and inspecting method for the semiconductor acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide semiconductor acceleration sensor having high reliability at a low cost. SOLUTION: A sensing element 1 has a weight part 5 rockably supported by a support part 16 via a thin-walled flexible part 4, and a gauge resistance 6 is formed on the flexible part 4. Upper and lower caps 2 and 3 are joined to the element 1, on its principal surface side and on its back surface side, respectively. The upper and lower caps 2 and 3 have recesses 2a and 3a, respectively formed in their surfaces confronting the element 1. An inspection mark 18, having a cruciform planar shape, is provided on a middle part of a surface of the weight part 5 facing on the recess 2a, and a circular inspection window 29, enabling the inspection mark 18 to be visually perceived, is bored through the upper cap 2. The distance from the inspection mark 18 to a reference plane, standing at a fixed distance from the principal surface of the support part 16, is measured by using an optical range finder, thus making it possible to judge bending or warping of the flexible part 4, based on the result of the measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor acceleration sensor and a method for testing a semiconductor acceleration sensor.

[0002]

2. Description of the Related Art Conventionally, as a semiconductor acceleration sensor,
As shown in FIG. 11 and FIG.
6 has a weight portion 5 swingably supported via a pair of thin bending portions 4, and each of the bending portions 4 has two gauge resistors 6 each composed of a piezo resistor for detecting deformation of the bending portion 4. A sensor having a sensing element 1 formed and provided with a wiring 11 made of ap ⁺ diffusion layer from each gauge resistor 6 to a predetermined portion of a support portion 16 has been proposed. In addition, the above-mentioned bending part 4 is generally called a beam or a cantilever.

Here, the weight 5, the flexure 4 and the support 16 of the sensing element 1 are integrally formed by etching the silicon substrate 1a. That is, in the sensing element 1, a recess 10 a surrounding the weight portion 5 over the entire circumference is formed on the back surface side of the silicon substrate 1 a by using anisotropic etching or the like, and the recess 10 a is formed on the main surface side of the silicon substrate 1 a.
It is formed so as to surround the entire circumference substantially the weight portion 5 while leaving a slit 10 _1, 10 ₂ is bent section 4 communicating with.
In short, there is a gap of the width of the slit 10 between the inner peripheral surface of the support portion 16 and the outer peripheral surface of the weight portion 5 on the main surface side of the silicon substrate 1a.

In the sensing element 1, a silicon oxide film 8 is formed on a main surface of a silicon substrate 1a.
Silicon nitride film 9 is formed on silicon oxide film 8. On the main surface side of the support portion 16 of the silicon substrate 1a, a wiring 13 made of aluminum connected to the wiring 11 via the contact portion 12 and a pad 14 made of aluminum connected to the wiring 13 are provided. Here, the pad 14 is formed on the main surface side of a portion facing the weight portion 5 with the bending portion 4 interposed therebetween in the rectangular frame-shaped support portion 16, and the conductive pattern 2 provided separately is provided.
0 is electrically connected via a bonding wire 15 for use. The conductive pattern 20 is formed of, for example, a thick film conductor (for example, Ag / Pd) provided on a ceramic substrate.
And a lead or the like provided on a plastic or ceramic package. The lead material is copper alloy or 42 alloy (alloy of iron and nickel)
Are used.

A glass upper cap 2 is bonded to the main surface of the sensing element 1 via a bonding thin film 7 made of aluminum, and a glass lower cap 3 is bonded to the back surface.

An example of a method for manufacturing the above-described semiconductor acceleration sensor is as follows.

First, a silicon oxide film is formed on the entire surface of each of the main surface and the back surface of a single-crystal silicon wafer whose main surface has a crystal plane of (100), and thereafter, the wafer is formed using photolithography technology and etching technology. The slits 10 ₁ and 10 _{2 in} the silicon oxide film on the main surface of
Then, the exposed portion is etched to a predetermined depth (for example, about 6 to 30 μm) using the silicon oxide film on the main surface of the wafer as a mask.

Next, a silicon oxide film made of a thermal oxide film is formed on an exposed portion of the main surface of the wafer, and thereafter, the wiring 11 is formed by using a photolithography technique, an etching technique, or the like. The silicon oxide film on the surface is patterned, and then the p-type impurity is pre-deposited on the main surface side of the wafer by ion implantation using the patterned silicon oxide film as a mask. Thereafter, a silicon oxide film made of a thermal oxide film is formed on the exposed main surface of the wafer, and subsequently, a p-type impurity is driven to form a wiring 11 made of a p ⁺ diffusion layer.

Next, the silicon oxide film on the main surface of the wafer is patterned to form the gauge resistor 6, and thereafter, the p-type impurity of the p-type impurity is formed on the main surface side of the wafer by ion implantation using the patterned silicon oxide film as a mask. Perform predeposition. Thereafter, a silicon oxide film made of a thermal oxide film is formed on the exposed main surface of the wafer, and subsequently, a gauge resistor 6 is formed by driving a p-type impurity. When the steps up to this point are completed, the silicon oxide film formed on the main surface side of the wafer is
Becomes the silicon oxide film 8.

Thereafter, a silicon nitride film is formed on each of the main surface side and the back side of the wafer, and contact holes are provided in the silicon nitride film 9 and the silicon oxide film 8 on the main surface side of the wafer to form a metal layer made of aluminum on the wafer. Are formed on the entire surface on the main surface side, and the metal layer is patterned to form the wiring 13, the pad 14, and the bonding thin film 7.

After that, a protective film made of a silicon nitride film is formed on the entire surface on the main surface side of the wafer, and then the back surface of the wafer is formed using photolithography technology and etching technology to form the recess 10a. The silicon nitride film and the silicon oxide film on the side are patterned, and the recesses 1 are formed by anisotropic etching using an alkaline solution using the patterned silicon nitride film as a mask.
0a and slits 10 ₁ and 10 ₂ are formed. afterwards,
By removing unnecessary portions of the protective film and the silicon nitride film 9 on the main surface side of the wafer, a wafer on which many sensing elements 1 are formed can be obtained.

Thereafter, a sensor wafer obtained by anodically bonding the first glass substrate on which a number of upper caps 2 are formed and the second glass substrate on which a number of lower caps 3 are formed to the above-mentioned wafer is placed along a scribe line. By dicing, a semiconductor acceleration sensor (sensor chip) having the configuration shown in FIG. 11 is formed.

By the way, in the semiconductor acceleration sensor having the structure shown in FIGS.
Are bridge-connected, and the mass of the weight 5 is m,
When an acceleration α is applied in the thickness direction of the sensing element 1 (the vertical direction in FIG. 11), a force (inertia force) of mα acts on the weight 5 according to the magnitude of the acceleration α, and the weight 5 swings. As a result, the bending portion 4 is bent, and as a result, a stress is generated in the bending portion 4 due to distortion, and the resistance value of each gauge resistor 6 changes due to the piezoresistance effect. The detected acceleration can be detected. In other words, a voltage signal proportional to the acceleration can be obtained. That is,
As shown in FIG. 13, the above four gauge resistors 6 are connected to R1
If the above four pads 14 are p1 to p4, the four piezo resistors R1 to R4 are bridge-connected as shown in FIG.
If a constant voltage source is connected between the pads 4, the change in resistance of the piezo resistors R1 to R4 can be detected as a change in voltage between the pads p2 and p3.

The upper cap 2 and the lower cap 3 each have a recess 2a for securing a swing space (air gap between the weight 5) of the weight 5 on the surface facing the weight 5. 3a is formed by sandblasting or the like. In sandblasting, the particle size is
By injecting abrasive grains such as 0 μm alumina etc. to physically recess 2
a, 3a are dug.

However, in the above-described semiconductor acceleration sensor, the swing range of the weight 5 is suppressed by the air damping effect to prevent the bending of the bending portion 4 of the sensing element 1. Here, the distance between the bottom surface of each of the recesses 2a and 3a, the weight 5, and the like are set so that the sensing element 1 has an attenuation characteristic by an air damping effect and the frequency characteristic of the sensor itself is optimized. That is, the damping property is provided by using the air damping effect so as not to cause resonance, thereby preventing the bending portion 4 from being broken.

Further, the upper cap 2 and the lower cap 3 respectively adjust the displacement range of the weight portion 5 when an excessive acceleration is applied, at an appropriate position on the bottom surface of the recesses 2a, 3a opposite to the weight portion 5. Small stoppers 2b, 3b for regulating are protruded. In short, when an excessive acceleration is applied, the weight portion 5 stops the stoppers 2b, 3b.
, The displacement of the bending portion 4 due to excessive displacement of the weight portion 5 can be prevented.

In the above-described semiconductor acceleration sensor, the wiring 11 connecting the connection point of the pair of gauge resistors R1 and R4 formed on one bending portion 4 to the pad p1 and the pair of wirings formed on the other bending portion 4 are provided. Since the wiring 11 connecting the connection point between the gauge resistors R2 and R3 and the pad p3 is routed so as to straddle the weight portion 5 and the support portion 16, the bending portion 4
When the wire is broken, the wiring 11 is broken, so that a failure such as the bending of the bent portion 4 can be detected outside (refer to Japanese Patent Application Laid-Open No. 9-166618).

As shown in FIG. 15, a detecting resistor 19 composed of a diffused resistor inserted between the two pads 14 and 14 'separately from the gauge resistor 6 is provided on the main surface side of the support portion 16, and Wiring 1 on pad 14 'side of resistor 19
A configuration in which the bending of the bending portion 4 is detected by pulling the 1 'over the supporting portion 16, the bending portion 4, and the weight portion 5 has also been proposed (Japanese Patent Application No. 11-24044).
No. 4).

[0019]

Since a semiconductor acceleration sensor is used for detecting an acceleration in an air bag of an automobile, an ABS (Anti-lock brake system), etc., high reliability is required. It is necessary to have a failure diagnosis function that can judge. Therefore, as described above, in the devices described in JP-A-9-166618 and Japanese Patent Application No. 11-240444,
And wiring 11, 11 ′ extending over the weight 5 and the wiring 11,
It is possible to detect the bending of the bending portion 4 and the disconnection of the wiring 11 by the presence or absence of energization to 11 ′. In short, the wiring 11, 11 '
Since the failure can be determined by the presence or absence of power supply to the sensor, it can be determined at the time of probing inspection for each wafer in which the upper caps 2, 3 are bonded to the sensing element 1, or after assembling and mounting on a circuit board and assembling into a housing (package). Also at the time of the final characteristic inspection, the bending of the bent portion 4 can be detected based on the presence or absence of energization of the wirings 11 and 11 '.

Incidentally, a method of inspecting the bending of the bending portion 4 by visual inspection or appearance inspection by an optical microscope or the like is also conceivable. However, since the recess 2a of the upper cap 2 is formed by sandblasting, the recess 2a
Are formed on the bottom surface of the substrate, and the bottom surface of the concave portion 2a is a frosted glass-like rough surface. In the appearance inspection using an optical microscope, light is irregularly reflected and the focus is blurred. There was a problem. However, if the bent portion 4 is broken in the process after the probing inspection in wafer units, it is not known that the bent portion 4 is broken until the final inspection after mounting on the circuit board and assembling into the housing. Many processes are wasted and relatively expensive circuit boards and packages are added and then discarded, resulting in a problem that the cost is increased.

In the above-described semiconductor acceleration sensor, if the warpage of the bending portion 4 is large, the weight portion 5 and the recess 2
Since the deviation from the design value of the distance between a and 3a becomes large, the frequency characteristic is deteriorated and resonance occurs, and the bending portion 4 is damaged by an impact when the weight portion collides with the stoppers 2b and 3b. There is a possibility that the sensing element 1
After the upper cap 2 and the lower cap 3 were joined to each other, there was no means for measuring the warpage of the bent portion 4, so that there was a problem that it was difficult to increase the reliability.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a low-cost and highly reliable semiconductor acceleration sensor.

[0023]

According to a first aspect of the present invention, there is provided a semiconductor device having a frame-shaped supporting portion made of a semiconductor substrate, which is swingably supported via a thin bending portion. A sensing element having a weight part separated from the part and having a gauge resistor formed on the bending part for detecting deformation of the bending part, and a first recess provided on a surface facing the sensing element, and a main surface of the sensing element A first cap joined to the sensing element, and a second cap joined to the sensing back surface side with a second recess provided on the surface facing the sensing element, wherein the first recess is provided at a weight portion. The inspection mark is provided on a surface facing the place, and an inspection window for making the inspection mark visible is provided on the first cap, and the upper cap and the upper cap are provided on the sensing element. Inspection marks can be viewed even after the lower and lower caps have been joined, so use an optical distance measuring device such as an optical microscope to make non-contact and non-destructive By measuring the distance of the inspection mark with respect to a certain reference plane and performing an inspection that determines that the product is non-defective only when the measured distance is within the specified range, it is possible to extract a defective product with a bent or bent warpage. In addition, the cost can be reduced and the reliability can be improved.

According to a second aspect of the present invention, in the first aspect of the present invention, the inspection mark is provided at a distal end of the weight portion opposite to the bending portion side, and the inspection window is provided between the inspection mark and the support. Since it is formed in a long hole shape that is visible over the main surface of the portion facing the tip of the weight portion in the portion, the main surface itself of the portion facing the tip of the weight portion is Since the reference plane can be used, the inspection accuracy can be improved as compared with the first aspect of the invention, and the reliability can be further improved.

According to a third aspect of the present invention, in the second aspect of the present invention, a plurality of pairs of the inspection mark and the inspection window are provided. By measuring and comparing, it is possible to inspect the presence or absence of torsion of the bent portion in addition to the bending or warpage of the bent portion.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the inspection mark is bent along a straight line parallel to a straight line connecting the weight portion, the bending portion, and the support portion. Since it is provided at the base end on the part side and the tip part on the side opposite to the bending part side, for example, by comparing the distance from the distance measuring device to each inspection mark, the inclination of the weight part and the warping of the bending part Inspection of breaks and the like becomes possible.

According to a fifth aspect of the present invention, there is provided the inspection method for a semiconductor acceleration sensor according to any one of the first to fourth aspects, wherein the inspection method is for inspecting a reference plane located at a fixed distance from the main surface of the support. The distance of the mark is measured, and when the measured distance is within a specified range, it is determined to be non-defective,
Since the distance of the inspection mark with respect to the reference plane can be measured by an optical distance measuring device or the like, even after the upper cap and the lower cap are joined to the sensing element, the bending and bending of the bent portion can be non-contact and non-contact. It is possible to provide a semiconductor acceleration sensor which can be inspected by destruction and has high reliability at low cost.

[0028]

(Embodiment 1) The basic configuration of a semiconductor acceleration sensor according to the present embodiment is substantially the same as the conventional configuration shown in FIGS. 11 and 12, and as shown in FIGS. It has a weight portion 5 swingably supported on a rectangular frame-shaped support portion 16 via a pair of thin bending portions 4, and each bending portion 4 is formed of a piezoresistor for detecting deformation of the bending portion 4. Two gauge resistors 6 are formed, and a wiring 11 made of ap ⁺ diffusion layer is formed from each gauge resistor 6 to a predetermined portion of the support portion 16.

The weight 5 of the sensing element 1
The bending portion 4 and the supporting portion 16 are integrally formed by etching the silicon substrate 1a. That is, the sensing element 1 has a recess 10a surrounding the weight 5 over the entire circumference on the back surface side of the silicon substrate 1a.
Are formed using anisotropic etching or the like, and the slits 10 ₁ and 10 ₂ communicating with the recesses 10 a on the main surface side of the silicon substrate 1 a surround the weight portion 5 over substantially the entire periphery except the bent portion 4. Is formed. In short, the main surface of the silicon substrate 1a, between the inner and outer circumferential surfaces of the weight portion 5 of the support portion 16, there will be a gap of only the width of the slit 10 _1.

In the sensing element 1, a silicon oxide film 8 is formed on a main surface of a silicon substrate 1a.
Silicon nitride film 9 is formed on silicon oxide film 8. On the main surface side of the support portion 16 of the silicon substrate 1a, a wiring 13 made of aluminum connected to the wiring 11 via the contact portion 12 and a pad 14 made of aluminum connected to the wiring 13 are provided. Further, similarly to the conventional configuration shown in FIG. 15, a detection resistor 19 made of a diffusion resistor inserted between the pads 14 and 14 'separately from the gauge resistor 6 is provided on the main surface side of the support portion 16, and Wiring 1 on pad 14 'side of resistor 16
By bending 1 ′ so as to straddle the support portion 16, the bending portion 4, and the weight portion 5, the bending of the bending portion 4 can be detected. Here, the pads 14 and 14 ′ are formed on the main surface side of a portion facing the weight portion 5 with the bending portion 4 interposed therebetween in the rectangular frame-shaped support portion 16, and are provided on the separately provided conductive pattern 20. It is used by being electrically connected via a bonding wire 15. In addition, the conductive pattern 20
For example, a thick film conductor provided on a ceramic substrate (for example,
Ag / Pd) or leads provided on a plastic or ceramic package.
As a material for the lead, a copper alloy, a 42 alloy (an alloy of iron and nickel), or the like is used.

An upper cap 2 made of heat-resistant glass having a coefficient of thermal expansion substantially equal to that of silicon is joined to the main surface side (upper surface side in FIG. 1) of the sensing element 1 by anodic bonding. Here, upper cap 2
Are joined to the sensing element 1 via a joining thin film 7 made of an aluminum thin film provided on the main surface side of the sensing element 1.

Further, a lower cap 3 made of heat-resistant glass having a thermal expansion coefficient substantially equal to that of silicon is joined to the back side (the lower side in FIG. 1) of the sensing element 1 by anodic bonding. Here, lower cap 3
Has a peripheral part joined to the support part 16 over the entire periphery.

The upper cap 2 and the lower cap 3
Recesses 2 for securing a swing space (air gap between the weights 5) of the weights 5 on the surfaces facing the weights 5, respectively.
a and 3a are formed by sandblasting or the like. In the sandblasting, the particle size is several tens μm.
The abrasive grains such as alumina are sprayed to physically remove the recesses 2a, 3
digging a. In this embodiment, the upper cap 2 is the first cap, the lower cap 3 is the second cap, the recess 2a is the first recess, and the recess 3a is the second recess, respectively. Make up.

In the semiconductor acceleration sensor according to the present embodiment, an inspection mark 18 having a cross shape in a plane is provided at the center of the surface desired for the recess 2a in the weight 5 so that the inspection mark 18 can be visually recognized. It is characterized in that a circular inspection window 29 is provided through the upper cap 2.

In the semiconductor acceleration sensor according to the present embodiment, the swing range of the weight 5 is suppressed by the air damping effect to prevent the flexure 4 of the sensing element 1 from being broken. Here, sensing element 1
Each of the recesses 2a, 3 has a damping characteristic by an air damping effect so that the frequency characteristic of the sensor itself is optimized.
The distance, etc., are set for the bottom surface of "a", the weight portion 5, and the like. That is, the damping property is provided by using the air damping effect so as not to cause resonance, thereby preventing the bending portion 4 from being broken. The upper cap 2 and the lower cap 3
Are small stoppers 2 for regulating the displacement range of the weight portion 5 when an excessive acceleration is applied, at appropriate positions of the portions facing the weight portion 5 on the bottom surfaces of the recesses 2a and 3a, respectively.
b, 3b are protruded. In short, when an excessive acceleration is applied, the weight portion 5 abuts against the stoppers 2b and 3b, so that the weight portion 5 is not further displaced. Destruction can be prevented.

An example of a method for manufacturing the semiconductor acceleration sensor according to the present embodiment is as follows.

First, a silicon oxide film is formed on the entire surface of each of the main surface and the back surface of a single crystal silicon wafer whose main surface has a crystal plane of (100), and thereafter, the wafer is formed using photolithography technology, etching technology, or the like. The slits 10 ₁ and 10 _{2 in} the silicon oxide film on the main surface of
Then, the exposed portion is etched to a predetermined depth (for example, about 6 to 30 μm) using the silicon oxide film on the main surface of the wafer as a mask.

Next, a silicon oxide film made of a thermal oxide film is formed on an exposed portion of the main surface of the wafer, and thereafter, the wiring 11 is formed by using a photolithography technique, an etching technique, or the like. The silicon oxide film on the surface is patterned, and then the p-type impurity is pre-deposited on the main surface side of the wafer by ion implantation using the patterned silicon oxide film as a mask. Thereafter, a silicon oxide film made of a thermal oxide film is formed on the exposed main surface of the wafer, and subsequently, a p-type impurity is driven to form a wiring 11 made of a p ⁺ diffusion layer.

Next, the silicon oxide film on the main surface of the wafer is patterned to form a gauge resistor 6, and thereafter, the p-type impurity of p-type impurity is implanted on the main surface side of the wafer by ion implantation using the patterned silicon oxide film as a mask. Perform predeposition. Thereafter, a silicon oxide film made of a thermal oxide film is formed on the exposed main surface of the wafer, and subsequently, a gauge resistor 6 is formed by driving a p-type impurity. The silicon oxide film formed on the main surface side of the wafer at the time when the steps up to this point are completed becomes the silicon oxide film 8 in FIG.

Thereafter, a silicon nitride film is formed on each of the main surface side and the back surface side of the wafer, contact holes are provided in the silicon nitride film 9 and the silicon oxide film 8 on the main surface side of the wafer, and aluminum is sputtered. Subsequently, by performing a heat treatment (so-called sintering), the wiring 13, the pads 14, 14 ', the bonding thin film 7, and the inspection mark 18 are respectively formed of aluminum (the wiring 13 is formed by the heat treatment at this time). Are connected to the wiring 11 at the contact portion 12).

Thereafter, a mask layer made of a resist layer or a nitride film is formed on the entire surface on the main surface side of the wafer.
Subsequently, the silicon nitride film and the silicon oxide film on the back surface side of the wafer are patterned by using photolithography technology and etching technology to form the recess 10a, and an alkaline solution is formed using the patterned silicon nitride film as a mask. The recess 10a and the slits 10 ₁ and 10 ₂ are formed by anisotropic etching using the method. Thereafter, unnecessary portions of the mask layer and the silicon nitride film 9 on the main surface side of the wafer are removed to obtain a wafer on which many sensing elements 1 are formed. In addition,
When the mask layer is a resist layer, it may be removed by an organic solvent after ashing by an ashing device, for example, and may be removed by a buffer hydrofluoric acid or the like when the mask layer is a silicon nitride film.

Thereafter, a sensor wafer obtained by anodically bonding the first glass substrate on which a large number of upper caps 2 are formed and the second glass substrate on which a large number of lower caps 3 are formed to the above-described wafer, is cut along a scribe line. By dicing, a semiconductor acceleration sensor (sensor chip) having the configuration shown in FIG. 1 is formed.

Also in the semiconductor acceleration sensor of this embodiment, similarly to the conventional configuration shown in FIGS. 11 and 12, the above-described four gauge resistors 6 are bridge-connected, and the mass of the weight 5 is m, When acceleration α is applied in the thickness direction of sensing element 1 (vertical direction in FIG. 1),
According to the magnitude of the acceleration α, a force (inertia force) of mα acts on the weight portion 5 and the weight portion 5 swings, whereby the bending portion 4 bends. As a result, a stress is generated in the bending portion 4 due to distortion. Since the resistance value of each gauge resistor 6 changes due to the piezoresistance effect, the applied acceleration can be detected by extracting the change in the resistance value as a voltage signal.
In other words, a voltage signal proportional to the acceleration can be obtained.

In the semiconductor acceleration sensor according to the present embodiment, as described above, the inspection mark 18 having a cross shape in a plane is provided at the center of the surface desired for the recess 2 a in the weight portion 5. Since the circular inspection window 29 through which the upper cap 2 can be visually recognized is provided through the upper cap 2, even after the upper cap 2 is joined to the sensing element 1, for example, as shown in FIG. The inspection mark 18 can be visually recognized by using this. In short, since the light emitted from the optical microscope 23 through the lens 22 is reflected by the inspection mark 18, the inspection mark 18 can be visually recognized through the inspection window 29. Therefore, for example, by measuring the distance of the inspection mark 18 with respect to a reference plane at a certain distance from the main surface of the support portion 16 and determining that the inspection mark 18 is non-defective only when the measured distance is within the specified range, the bending portion It is possible to extract defective products whose 4 is broken or whose warpage is too large, so that the cost can be reduced and the reliability can be improved.

FIG. 4 shows an example of a schematic configuration of an inspection system for inspecting the bent or warped portion 4 of the sensor wafer W described above. The sensor wafer is set on an XYθ table 24 and an inspection mark on the main surface of the weight 5 is formed. The position of 18 is displayed on a digital position display device (for example, a Magnescale manufactured by Sony). Further, for example, an inspection mark 18 for a reference plane located at a certain distance from the main surface of the support 16
By adjusting the focus adjustment screw 27 of the optical microscope 23, the measurement data of the distance when the inspection mark 18 and the XYθ table 24 are focused can be measured by a processing device (for example, a Digimatic Mini manufactured by Mitutoyo Corporation). Processor 25). Therefore, for example, in the processing device 25, the inspection mark 1 with respect to the reference plane is set with the upper surface of the XYθ table 24 as the reference plane.
8 is calculated, and the calculation result is displayed on the display device. If the calculation result is within a predetermined range, it is determined that the bending portion 4 is not broken and the bending portion 4 is not warped. What should I do? In other words, if the calculation result is not within the predetermined range, it can be determined that the bent portion 4 is a broken or bent excessively defective product. In short, even in the state of the sensor wafer W after the upper cap 2 and the lower cap 3 are joined to the sensing element 1, the distance of the inspection mark 18 with respect to the reference plane can be measured by an optical distance measuring device or the like. Part 4
Inspections such as bending and warping can be performed in a non-contact and non-destructive manner, and a low-cost and highly reliable semiconductor acceleration sensor can be provided.

The warp of the flexure 4 is determined by measuring the distance of the inspection mark 18 with respect to a reference plane located at a fixed distance from the main surface of the support 16 by the knife edge method using laser light of a single wavelength. In this case, for example, an ultra-high-precision non-contact three-dimensional measuring device manufactured by Nippon Digitech may be used.

(Embodiment 2) The basic configuration of a semiconductor acceleration sensor of this embodiment is substantially the same as that of Embodiment 1, and FIG.
As shown in FIG. 6 and FIG.
The inspection window 2 is provided at the tip end opposite to the bending portion 4 side of the inspection window 2.
9 is characterized in that it is formed in a long hole shape that allows the inspection mark 18 and the support portion 16 to be visible over the main surface of the portion facing the tip of the weight portion 5. In addition,
The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

Thus, in the semiconductor acceleration sensor according to the present embodiment, even in the state of the sensor wafer W after the upper cap 2 and the lower cap 3 are joined to the sensing element 1, the tip of the weight 5 in the inspection mark 18 and the support 16 is provided. The main surface of the support 16 can be visually recognized by measuring the distance from the optical distance measuring device to each of the support 16 and the inspection mark 18. Inspection mark 1 for reference plane including
Since the distance of 8 can be calculated, the inspection accuracy of the warpage of the bent portion 4 is further improved as compared with the inspection method of the first embodiment. Further, the distance from the slit 10 ₁ to the inspection marks 18 is measured at the tip side of the weight portion 5, measured distance is flexure 4 is folded to missing or if inspection mark 18 not within the predetermined distance May be determined.

(Embodiment 3) The basic configuration of a semiconductor acceleration sensor according to the present embodiment is substantially the same as that of Embodiment 2, and FIG.
And the inspection mark 18 and the inspection window 2 as shown in FIG.
9 is provided in two sets. Here, the inspection marks 18 are juxtaposed on the main surface of the weight portion 5 in a direction orthogonal to the extension direction of the bending portion 4 (arranged vertically in FIG. 8). Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Thus, in the semiconductor acceleration sensor according to the present embodiment, similarly to the second embodiment, it is possible to detect the warpage or breakage of the bending portion 4 in the state of the sensor wafer W. By measuring and comparing the distance of the inspection mark 18 with respect to the reference plane with respect to the mark 18, it is possible to inspect the presence or absence of twisting of the bending portion 4 in addition to bending or warping of the bending portion 4, and the twist is large ( In other words, in the case where the difference between the two reference marks 18 with respect to the reference plane is not in the specified range, the defective part in which the torsion of the bending portion 4 is large may be used.

(Embodiment 4) The basic configuration of a semiconductor acceleration sensor according to the present embodiment is substantially the same as that of Embodiment 1, and FIG.
As shown in FIG. 10 and FIG. 10, two sets of the inspection mark 18 and the inspection window 29 are provided. here,
The inspection mark 18 is provided on the main surface of the weight 5 at the bent portion 4.
(Parallel to the left and right direction in FIG. 10). That is,
In the semiconductor acceleration sensor of the present embodiment, the inspection mark 18 is provided at the base end of the weight portion 5 on the side of the bending portion 4 and on the distal end of the weight portion 5 on the side opposite to the side of the bending portion 4. Embodiment 1
The same components as those described above are denoted by the same reference numerals, and description thereof is omitted.

Thus, in the semiconductor acceleration sensor of the present embodiment, the difference between the distance from the distance measuring device when each of the inspection marks 18 is in focus is obtained, whereby the weight 5 of the weight 5 with respect to the main surface of the support 16 is obtained. The inclination can be obtained, and it is possible to inspect the bent portion 4 for bending or warpage.

In each of the above embodiments, the inspection mark 18 is provided on the main surface of the weight 5 and the inspection window 29 is provided in the upper cap 2, but the depths of the recesses 2a and 3a are appropriately set. By doing so, an air damping effect can be obtained as in the conventional configuration. Further, the sensor chip is covered with a lid using a sealing adhesive while being stored in a package in a clean room.

[0054]

According to the first aspect of the present invention, there is provided a flexure portion having a weight portion which is swingably supported via a thin flexure portion and is separated from the support portion inside a frame-like support portion made of a semiconductor substrate. A sensing element formed at a bent portion with a gauge resistor for detecting deformation of the sensing element; a first cap provided with a first recess on a surface facing the sensing element and joined to a main surface side of the sensing element; A second cap provided on a surface facing the element and a second cap joined to the back side of the sensing element, and an inspection mark provided on a surface facing the first recess at a weight portion; An inspection window that allows the inspection mark to be visually recognized is provided in the first cap, and the inspection mark can be visually recognized even after the upper cap and the lower cap are joined to the sensing element. It is possible to measure the distance of the inspection mark with respect to a reference plane located at a certain distance from the main surface of the support part in a non-contact and non-destructive manner using an optical distance measuring device such as an optical microscope. By performing an inspection that is determined as a non-defective product only when it is within the specified range, it is possible to extract a defective product whose bent portion is bent or warped excessively, thereby reducing costs and increasing reliability. There is.

According to a second aspect of the present invention, in the first aspect of the present invention, the inspection mark is provided at a tip of the weight portion opposite to the bending portion side, and the inspection window is provided between the inspection mark and the support. Since it is formed in a long hole shape that is visible over the main surface of the portion facing the tip of the weight portion in the portion, the main surface itself of the portion facing the tip of the weight portion is Since the reference plane can be used, the inspection accuracy can be improved as compared with the first aspect of the invention, and there is an effect that reliability is further improved.

According to a third aspect of the present invention, in the second aspect of the present invention, a plurality of sets of the inspection mark and the inspection window are provided. Is measured and compared, there is an effect that it becomes possible to inspect the presence / absence of torsion of the bent portion in addition to bending and warping of the bent portion.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the inspection mark is bent along the straight line parallel to the straight line connecting the weight portion, the bending portion, and the support portion. Since it is provided at the base end on the part side and the tip part on the side opposite to the bending part side, for example, by comparing the distance from the distance measuring device to each inspection mark, the inclination of the weight part and the warping of the bending part In addition, there is an effect that it becomes possible to inspect for breakage.

According to a fifth aspect of the present invention, there is provided the method for inspecting a semiconductor acceleration sensor according to any one of the first to fourth aspects, wherein the inspection method is for inspecting a reference plane located at a fixed distance from the main surface of the support. The distance of the mark is measured, and when the measured distance is within a specified range, it is determined to be non-defective,
Since the distance of the inspection mark with respect to the reference plane can be measured by an optical distance measuring device or the like, even after the upper cap and the lower cap are joined to the sensing element, the bending and bending of the bent portion can be non-contact and non-contact. There is an effect that a semiconductor acceleration sensor which can be inspected by destruction and which is low in cost and highly reliable can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a first embodiment.

FIG. 2 is a schematic plan view showing a state where an upper cap is removed in the same.

FIG. 3 is a schematic sectional view showing a second embodiment.

FIG. 4 is a schematic plan view showing a state where an upper cap is removed in the same.

FIG. 5 is a schematic sectional view showing a third embodiment.

FIG. 6 is a schematic plan view showing a state where an upper cap is removed in the same.

FIG. 7 is a schematic sectional view showing a fourth embodiment.

FIG. 8 is a schematic plan view showing a state in which an upper cap is removed in the same.

FIG. 9 is a schematic sectional view showing a fifth embodiment.

FIG. 10 is a schematic plan view of the same as above with the upper cap removed.

FIG. 11 is a schematic sectional view showing a conventional example.

FIG. 12 is a schematic plan view showing a state where an upper cap is removed from the above.

FIG. 13 is an explanatory diagram of a main part of the above.

FIG. 14 is an explanatory diagram of a main part of the above.

FIG. 15 is a plan view showing another conventional example with an upper cap removed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sensing element 1a Silicon substrate 2 Upper cap 2a recess 3 Lower cap 3a recess 4 Flexure 5 Weight 16 Support 18 Test mark 29 Test window

Continued on the front page (72) Inventor Hironori Kami 1048 Kazuma, Kadoma, Osaka Prefecture F-term in Matsushita Electric Works, Ltd. (reference) 4M112 AA02 BA01 CA23 CA25 CA33 CA36 DA05 DA10 DA11 DA12 DA17 DA18 EA03 EA06 EA07 FA07 GA01

Claims (5)

[Claims] 1. A gauge resistor for swingably supporting a frame-shaped supporting portion made of a semiconductor substrate through a thin bending portion and being separated from the supporting portion, and detecting a deformation of the bending portion. Are formed in the bending portion, a first recess is provided on a surface facing the sensing element, a first cap is joined to a main surface side of the sensing element, and a first cap is provided on a surface facing the sensing element. A second cap provided with two recesses and joined to the back surface side of the sensing, and an inspection mark provided on a surface facing the first recess in the weight portion so that the inspection mark can be visually recognized. A semiconductor acceleration sensor, wherein an inspection window to be inspected is provided in the first cap. 2. The inspection mark is provided at a distal end of the weight portion opposite to the bending portion side, and the inspection window faces the inspection mark and the distal end of the weight portion of the support portion. 2. The semiconductor acceleration sensor according to claim 1, wherein the semiconductor acceleration sensor is formed in a long hole shape that can be viewed over the main surface of the semiconductor acceleration sensor. 3. The semiconductor acceleration sensor according to claim 2, wherein a plurality of sets of the inspection mark and the inspection window are provided. 4. A method according to claim 1, wherein the inspection mark is formed along a straight line parallel to a straight line connecting the weight portion, the bending portion, and the support portion. 2. The semiconductor acceleration sensor according to claim 1, wherein the semiconductor acceleration sensor is provided at an opposite end. 5. The method for inspecting a semiconductor acceleration sensor according to claim 1, wherein a distance of the inspection mark from a reference plane located at a fixed distance from the main surface of the support is measured. A semiconductor accelerometer that is determined to be non-defective when the measured distance is within a specified range.