DE4218324A1 - Semiconductor extension sensor, e.g. for operating airbag system in motor vehicle - contains transfer system passing mechanical stress, e.g. caused by acceleration, to stress detection element - Google Patents

Abstract

The semiconductor extension sensor (10A) has a base, an edge region attached to the base via a mechanical connection, a central region, a flexible strut carrying a stress detection element and a stress transfer path. The central region extends out from the edge region and the strut extends out from the central region. The detection element's electrical properties change when a mechanical stress is applied. The strut is thinner than the central region and the transfer path transfers the stress into the detection element from the connection section. USE/ADVANTAGE - E.g. for measuring accelerations, mechanical stresses and extensions, e.g. for operating airbag systems in motor vehicles. Enables sufficiently accurate measurement of stresses caused by accelerations or other factors without significant influence by ambient temp. changes or ageing effects.

Description

The present invention relates to a semiconductor Strain sensor for the detection of accelerations, mechani tensions, strains or the like.

Such a semiconductor acceleration sensor is for example as an acceleration sensor in the field of Automotive technology used. Such a sensor has a piezo sensitive element. In the U.S. patent 49 67 597 or published in Japanese Patentan Message No. Hei2-2 31 571 is such a sensor Darge poses. The sensor has a boom and a ver bound and supporting the boom. The boom consists of a silicon chip and contains a thin one flexible web, which depending on the Be acceleration is deformed or deflected. By doing flexible web is formed a piezo-sensitive layer. The thickness of the flexible web is generally about 40 µm.

Such a sensor is used in particular in an airbag system stem (safety airbag) used to make the change in the Acceleration to within a predetermined period of time grasp. In general, the acceleration values are all in one Airbag system is relatively large and between about 5 G and 49 G.

In recent years it has been found that a derar acceleration sensor also for an ABS system (anti- Blocking system) can be used in automotive engineering can. The acceleration values in the ABS system are in space mean relatively low and are in areas of less  than 1.5 G. This sensor works for a predetermined time, however not regarding the change within the predetermined duration. Therefore, the output of the sensor must be in a li can respond to the acceleration in a near manner. About that in addition, the output properties of the sensor must not due to changes due to the ambient temperature or be influenced due to signs of aging. The Sensor contains at least one flexible bridge to hold a pie to supply a tension or elongation to the zoelectric element. The thickness of this flexible web is less than that about 15 µm, enough for the sensitivity of the sensor high to detect low accelerations values of less than 1.5 G by the sensor enable.

Due to changes in ambient temperature or on due to signs of aging cut between the boom and the base mechanical chip generated in the connection or contact. These mechanical tension in the connection in the acceleration The sensor is caused by the difference in the thermi expansion coefficient of the boom and the base, especially after a cooling process after contacting the Boom and the base at a relatively high temperature. The mechanical tension in the connection reaches the pie sensitive layer. If the sensor is very emp is sensitive, the output property of the sensor is determined by affects the tension in the connection so that the sensor especially low acceleration values are no longer accurate can capture enough.

To remedy this disadvantage and to reduce the on flow of tension in the connection on the sensitive Various measures were carried out using the sensor. In the case of a measure, the basis was selected in such a way that you coefficient of thermal expansion near the expansion extension coefficient of the boom. Another Measure became the base and the boom due to a contract  odenbond process contacted or bonded, in which the property has been observed to be lower mechanical Achieve tension in the connection. However, were on due to such conventional measures not sufficient achieved satisfactory results. Hence this highly sensitive semiconductor acceleration sensor in the ABS System not used to a considerable extent, son only mechanical acceleration sensors came for use.

Accordingly, the present invention has the object reason, a semiconductor strain sensor available make a sufficiently accurate record based on mecha generated by acceleration or the like factors African tension allows, without a noteworthy leg flow due to changes in ambient temperature or subject to signs of aging.

It is also an object of the present invention to Semiconductor strain sensor with high sensitivity for ver to provide.

This object is achieved according to the invention by features specified in claims 1, 20, 21 and 22.

The semiconductor strain sensor according to the present invention tion has a base, an edge area, a central area rich and a flexible bridge. The border area is with connected to the base. The mechanical tension in the connection is through a bond section or contacting cuts between the base and the edge area. The The central area extends away from the edge area. The flexible web extends away from the central area and has a voltage detection element. The tension detection element changes its electrical properties when mechanical tension is applied. The thickness of the flexible part is smaller than the thickness of the central area ches. The tension in the connection is from the bond-Ab  cut to the voltage sensing element via a transmission transmission path. The transmission path is bent.

If the voltage in the connection over the transmission path is transmitted, the voltage in the connection is abge weakens because it is at a bending section of the transmission Path is distributed so that only part of the tension is transmitted along the transmission path. Therefore even with a thinner design of the flexible web to increase the sensitivity of the sensor mechanical tension detected with sufficient accuracy be without an adverse influence due to the Span connection is present.

Advantageous further developments of the invention result from the subclaims.

Further details, aspects and advantages of the present Invention result from the following description un ter reference to the drawing.

It shows

Figure 1 is a partially sectioned view of a semiconductor acceleration sensor according to a first embodiment of the present invention.

Fig. 2 is an enlarged side sectional view of the sensor, taken along the line L 2 -L 2 of Fig. 1;

Fig. 3 is a substantially enlarged perspective view of the sensor of FIG. 1;

Fig. 4 is a substantially enlarged plan view of the sensor according to FIGS. 1-3.

FIG. 5 is a substantially enlarged side view of the sensor, taken along the line L 5 -L 5 from FIG. 4;

Fig. 6 is an enlarged plan view of the sensor with a plurality of wiring structuring;

Fig. 7 is an electrical circuit diagram of the sensor according to the first embodiment;

Fig. 8-12 sectional side views of the sensor elements of the sensor according to Figures 1-6 to illustrate the successive steps in the manufacturing process;

FIG. 13 is a considerably enlarged partial sectional view of a chip that forms part of the sensor according to FIGS . 1-6;

Figs. 14 and 15 are schematic diagrams for explaining the relationship between the temperature and the Varia tion in the offset voltage;

FIG. 16 is a greatly enlarged partial side sectional view of the silicon chip of the Sen sors shown in FIGS 1-6.

Figure 17 is a plan view of a chip part of the semiconductor acceleration sensor according to a second embodiment of the present invention forms the.

FIG. 18 is a sectional side view of the chip, genome men along the line L 18 -L 18 of FIG. 17;

FIG. 19 is a plan view of a silicon chip which forms a part of the semiconductor acceleration sensor accordingly to a third embodiment of the present invention;

FIG. 20 is a plan view of a silicon chip which forms a part of a semiconductor acceleration sensor accordingly to a fourth embodiment of the present invention;

FIG. 21 is a plan view of a silicon chip which forms a part of a semiconductor acceleration sensor accordingly to a fifth embodiment of the present invention;

FIG. 22 is a plan view of a silicon chip which forms a part of a semiconductor acceleration sensor accordingly to a sixth embodiment of the present invention; and

Fig. 23 is a plan view of a silicon chip which forms part of a semiconductor acceleration sensor according to a seventh embodiment of the present invention.

First embodiment

Figs. 1 and 2 show a semiconductor Beschleunigungssen sor 10 A for the use of an ABS system in generating an accelerator. The sensor 10 A is encapsulated in a housing 11 A.

The housing 11 A generally has a lower housing part, for. B. a foot 1 , and an upper housing part or a shell 2 . The foot 1 is made of a metallic material, such as Kovar, and the cover 2 is also made of a metallic material, such as steel. The foot 1 has a soldering section 13 A, which extends along the outer edge of the foot 1 , and a raised section 3 , which is surrounded by the soldering section 13 A. The envelope 2 has the general shape of a box with an opening at the lower end and has flange 14 A, which he stretch around the open lower surface. The flange edges 14 A of the shell 2 and the Lötab section of the foot 1 are closed with a known soldering method and bonded or bonded together.

The housing 11 A contains a sensor 10 A, which will be described in more detail below. For access to the Sensos 10 A, the raised section 3 is equipped with four through openings that accommodate four electrical connections 4 . The electrical connections 4 are connected to the base 1 due to a so-called glass fusion process. The foot 1 also has a pair of openings 5 for attaching the sensor 10 A to a vehicle.

In FIGS. 3-5, the elements of the sensor 10 are A greater clarity in FIG. The sensor 10 A has a base 7 , which is attached to the raised portion 3 , and has a chip 6 , which is placed on the base 7 . The base 7 is preferably made of a Pyrex glass material, but alternatively, another insulating material can also be used. Pyrex is a registered trademark of the company Corning Glass Works. The base 7 essentially has a flat, square shape. The silicon chip 6 is bonded to the upper surface of the base 7 . The chip 6 is essentially of a generally square, flat shape and has a thickness of approximately 350 μm.

In this preferred embodiment, the chip 6 is made of silicon. However, it goes without saying for the person skilled in the art that, alternatively, another semiconductor material, such as, for example, gallium arsenide, can also be used. The chip 6 has an upper surface 8 and a lower surface (not shown). The lower surface is bonded to the base 7 . The upper surface 8 has a substantially square configuration and comprises an edge area 8 A and a central area 9th The edge area 8 A and the central area 9 are generally separated by a gap 11 , but are connected to one another by means of a connecting part 13 .

The central area 9 has a substantially U-shaped part, a mass 10 and a plurality of flexible webs 14-17 . The mass 10 is in wesent union within the central area 9 , which is connected to the mass 10 via a plurality of flexible webs 14 , 15 , 16 and 17 . While only four webs are explained in this preferred embodiment, it goes without saying that any other number of flexible webs can alternatively be used without departing from the basic idea of the present invention. The mass 10 is separated from the central area 9 and the edge area 8 A by four gaps, which are indicated by the reference numerals 12 a, 12 b, 12 c and 12 d.

The central area 9 consists of three interconnected parts, so that the U-shaped arrangement is formed. A Zen tralteil 9 A is in the middle with the connecting part 13 connected ver. Two substantially similar lateral parts 9 B and 9 C extend from it and are arranged symmetrically with respect to the central part 9 A. The flexible webs 14 , 15 , 16 and 17 extend inwards from the lateral parts 9 B and 9 C for the connection of the lateral parts to the mass 10 . Although the preferred embodiment shows a number of two flexible webs extending from each lateral part, it goes without saying that modified versions are also encompassed by the present invention.

The thickness of the central region 9 , the mass 10 and the connecting part 13 is substantially similar to the thickness of the edge region 8 A. The thickness of the flexible webs 14 , 15 , 16 and 17 is generally smaller than the thickness of the edge region 8 A and is approximately 5 µm.

On the flexible webs 14 , 15 , 16 and 17 each pair of wise piezo-sensitive layers 18 a and 18 b, 19 a and 19 b, 20 a and 20 b and 21 a and 21 b are formed.

A recess 22 is also formed in the base 7 in order to enable the mass 10 to be displaced in the vertical direction therein, in accordance with the acceleration to be measured. The depth of the recess 22 is selected such that the mass, the base 7 does not affect a normal acceleration is applied to the sensor 10 A to 10th

Referring to Fig. 6 is shown a tion of lines Verdrahtungsstrukturie formed on the chip 6. These lines are preferably made of aluminum Herge, but other, similar materials could also be used if A first set of lines 41, 42, 43 and 44 A 8 is arranged along one side of the edge region. The line 41 is used for the ground of a Wheatstone bridge circuit described below. The line 42 is used for the connection of a power supply for the circuit, the lines 43 and 44 are used for the output of a potential difference as a function of the existing acceleration.

A second set of four lines 45, 46, 47 and 48 A 8 is arranged along another side of the edge region. Line 45 is used for the bulk of the Wheatstone bridges circuit; line 46 is used for connection to the line supply; and lines 43 and 44 are used to output a potential difference as a function of acceleration. The selection of the lines depends on the direction of installation of the chip 6 on the base 7 . The sensor 104 of the present embodiment uses the first set of aluminum lines 41 , 42 , 43 and 44 .

An impurity diffusion layer 49 is diffused in the chip 6 at about the center of the line 42 . The line 41 crosses the impurity diffusion layer 49 and is separated therefrom by a silicon oxide film. The line 46 is electrically connected to the line 42 via an impurity diffusion layer 50 . The line 45 is electrically connected to the line 41 via an impurity diffusion layer 51 . The line 47 is electrically connected to the line 43 via an impurity diffusion layer 52 . The impurity diffusion layers 50 , 51 and 52 are diffused into the chip 6 . The line 48 is electrically connected to the line 44 via an impurity diffusion layer 53 . The impurity diffusion layer 53 is diffused into the chip 6 and is used to set a resistance value.

The lines described above and the piezo-sensitive layers 18 a, 18 b, 19 b, 20 a, 20 b, 21 a and 21 b are electrically connected to one another such that the Wheatstone bridge circuit 7 A is formed, as shown in Fig. 7 Darge is. The Wheatstone bridge circuit 7 A has four connections 35 , 36 , 37 and 38 , of which the connection 35 is grounded and the connection 36 is connected to the power supply. The potential difference between the output terminal 37 and the output terminal 38 generally changes as a function of the acceleration to be measured. These four connections 35 , 36 , 37 and 38 are connected to the electrical connections 4 via wires 23 , as shown in FIGS. 1 and 2.

Figs. 1 and 2 also show two partition walls 24, which extend within the recesses in the sleeve 2. The partition 24 is fastened to the sheath 2 on the basis of a suitable bonding method, for example on the basis of point soldering. Each of the partitions 24 has a communicati ons opening 27 which connects the chambers A and B. The partitions 24 are spaced apart to define a communication opening 25 for the respective connection of the two lower and upper subchambers A and B.

The opening 25 extends above the partitions 24 . The positions of the openings 27 are lower than the position of the opening 25 . The housing 11 A of the sensor 10 A contains gas and damping liquid 26 , such as silicone oil. The openings 27 allow outflow of the damping fluid 26 from the upper chamber B to the lower chamber A under the action of gravity. The partition is known per se and is described, for example, in further details in US Pat. No. 4,967,597, to which reference is hereby expressly made in full.

The method for producing the sensor element described above will now be explained with reference to FIGS. 8-12. It is initially assumed that, for reasons of simplicity of illustration, only one piezo-sensitive layer is drawn in each of the flexible webs according to FIG. 12. In addition, Figs. 8-12 show only one sensor 10 A, although of course a plurality of sensors are formed on a single wafer.

First, a silicon wafer 28 of the N ^- type is made available according to FIG. 8. This wafer 28 corresponds to the silicon chip 6 shown in FIGS. 3-6. A first silicon oxide film 29 is formed on the entire surface of a first or upper surface of the wafer 28 . The silicon oxide film 29 has a thickness of about 4500 Å. Via a photo etching process, predetermined areas of the silicon oxide film 29 are removed, so that P⁺ diffusion layers 30 are formed in front of certain areas of the wafer 28 .

Then, a second silicon oxide film 31 is formed on the entire surface of the first surface by a CVD (Chemical Vapor Deposition) process. The silicon oxide film 31 has a thickness of about 4000 Å. Predetermined areas 21 of the silicon oxide films 29 and 31 are then removed by the photoetching method, as shown in FIG. 9.

Then, a silicon oxide film 32 is formed on an exposed portion of the upper surface of the wafer 28 , as shown in FIG. 10. The silicon oxide film 32 has a thickness of about 1000 Å. A mask with a predetermined patterning is arranged on the silicon oxide film 32 , and P⁺ diffusion layers 33 are formed in the wafer 28 by ion implantation. These layers represent piezo-sensitive layers and connect the P⁺ diffusion layers 30 .

Subsequently, contact holes in the silicon oxide films 32 on the P⁺ diffusion layers 30 are opened, as shown in FIG. 11. Aluminum lines 34 are formed on the contact holes and on the silicon oxide films 31 and 32 . The aluminum lines 34 connect the P⁺ diffusion layers 30th

Predetermined areas of the wafer 28 are etched away from a second or bottom surface opposite the first surface such that the thickness of the predetermined areas of the wafer 28 is approximately 5 µm, as shown in FIG. 12. It is noted that this thickness is set according to the desired sensitivity of the 10 A sensor. Then predetermined areas of the wafer 28 are etched away from the first surface by more than 5 μm. The areas etched away from the first surface correspond to some of the areas etched away from the second surface to form the gaps 11 , 12 a, 12 b, 12 c and 12 d.

FIG. 13 shows the wafer 28 and the silicon oxide films 29 , 31 and 32 in a considerably enlarged illustration in this step of the production process. As shown in Fig. 13, the thickness of the silicon oxide film 32 formed on the flexible lands 14-17 is about 1000 Å. On the other hand, the thicknesses of the silicon oxide films 29 and 31 formed on a thicker portion of the wafer 28 with a larger thickness than the thicknesses of the flexible lands 14-17 are 4000 Å and 4500 Å, respectively. The silicon oxide film 32 extends from the flexible lands 14-17 to the thicker portions by a length D as shown in FIG. 13.

The wafer 28 is then anode-bonded with the base 7 . The wafer 28 and the base 7 are divided into chips in the sensor 10 A, as shown in FIG. 3. The base 7 is bonded to the raised section 3 . The sleeve 2 is bonded to the foot 1 , and the housing 11 A is filled with damping liquid 26 .

After the arrangement of the sensor 10 A has been completed, the sensor 10 A is mounted in a vehicle and arranged in particular in a predetermined directional relationship with the vehicle, so that the chambers A and B in Chen essentially with the damping liquid 26 and Gas are filled.

When an acceleration acts on the sensor 10 A, the mass 10 is deflected due to the inertia in such a way that a mechanical tension or an expansion occurs in the flexible webs 14-17 as a function of the displacement of the mass 10 . As a result, a bridge output based on the change in the piezo sensitive value of the piezo sensitive layers 18 a, 18 b, 19 a, 19 b, 20 a, 20 b, 21 a and 21 b at the output terminals 37 and 38 of the bridge circuit 7 A receive.

The output connections 37 and 38 are connected to a control (not shown in more detail) for the ABS system. The controller detects the acceleration of the vehicle as a function of the voltage between the output terminals 37 and 38 . The controller also calculates the deceleration of the vehicle to determine the friction between the vehicle's tires and the road surface. The controller then calculates an appropriate reference speed based on this friction value and controls the wheel slip rate such that an actual speed is approximately equal to the reference speed.

The voltage generated in the connection on a bond section 6 A between the edge area 8 A and the base 7 can reach the flexible webs 14-17 via the transmission paths R 2 , R 1 , R 4 and R 3 , as shown in FIG. 4 is shown. As used in the present specification, the transmission path is defined as the conduit that extends along the central area 9 and a flexible web. The transmission paths R 1- R 4 extend along the connec tion part 13 , the central area 9 and the flexible webs 14-17 .

According to the sensor 10 A of the present embodiment, the transmission paths R 1- R 4 are bent three times, and each time approximately at a right angle. For example, the transmission path R 1 is first bent between the support part 13 and the central part 9 A of the central region 9 . The path R 1 is then bent between the central part 9 A and the lateral part 9 A of the central region 9 . The path R 1 is fer ner between the lateral part 9 A and the flexible web 15 bent.

If the tension in the connection is transmitted via the transmission paths R 1- R 4 , it is weakened because it is distributed in the bending sections of the transmission paths R 1- R 4 , so that only part of the mechanical stress along the transmission paths R 1 - R 4 is transmitted.

It also allows the transmission path to bend the formation of a long transmission path in a rela tiv small area.

If the gap 11 were not provided, the tension in the connection to the flexible web would be transmitted closer to the corresponding edge region 8 A. According to the present invention, however, the tension in the connection to the flexible webs 14-17 is transmitted along a selected path, unlike the near side of the edge region 8 A, since the gap 11 separates these flexible webs from the edge region 8 A and thus enables a path via the connec tion part 13 . As a result, the transmission paths R 1- R 4 are extended, and the tension in the connection on the flexible webs 14-17 is further weakened. Accordingly, it is now possible to reduce the thickness of the flexible webs 14-17 in order to improve their sensitivity and to substantially reduce or even completely eliminate the influence of the stress in the connection on these flexible webs.

FIGS. 14 and 15 show the result of experiments to determine the effect of the mechanical stress in the connection to the flexible webs 14-17. The abscissa of FIGS. 14 and 15 denote the ambient temperature in degrees Celsius, the ordinate denote corresponding changes in the offset voltage in volts. The offset voltage represents the voltage between the output connections 37 and 38 when the acceleration is not present at the sensor 10 A. FIG. 14 shows the result of the sensor 10 A of the present exemplary embodiment, and FIG. 15 shows the result of a sensor which is approximately identical to the sensor 10 A of the present exemplary embodiment, but which has no gap 11 . As shown in FIGS. 14 and 15, the change W 2 in the offset voltage of the sensor 10 A of the present embodiment contributes about a quarter of the change W 1 of the sensor without the gap 11 .

As previously mentioned in reference to FIG. 13, the thickness of the silicon oxide film 32 formed on the flexible lands 14-17 is approximately 1000 Å and the thicknesses of the silicon oxide formed on the thicker portions of the wafer 28 -Films 29 and 31 each about 4000 Å and 4500 Å. The thin film 32 on the flexible web 14-17 is another advantage in terms of protecting the flexible webs. If the films 29 and 31 are stretched to cover the flexible webs 14-17 , the flexible webs 14-17 will be protected in this context during the cooling process of the films 29 and 31 , respectively.

The flexible webs 14-17 extend into the Stützab section, as shown in FIGS . 5 and 13. The support sections have a greater thickness than the flexible webs 14-17 . These form the edge area 9 and the mass 10 . The P⁺ diffusion layer 33 extends from the flexible webs 14-17 to the support sections. The silicon oxide film 32 extends from the flexible webs 14-17 to the support portions. The layers 32 are covered in wesent union by the thin silicon oxide film 32 , but not by the thicker silicon oxide film 29 or 31 , in order to reduce the effect of the voltage on the piezo resistance of the layers 33 . In fact, the voltage generated between the wafer 28 and the silicon oxide film formed on the wafer 28 has an influence on the piezo resistance of the layers 33 , since the magnitude of the mechanical stress varies in proportion to the thickness of the silicon oxide film.

The following problem could be eliminated if the thin silicon oxide film 32 were formed on the flexible lands 14-17 , that is, on the entire surface of the support portions, and the thicker silicon oxide films 29 and 31 were not formed at all, as described above would be. Fig. 16 shows the impurity diffusion layers 54 and 55 which have been diffused beneath a silicon oxide film 56 and an aluminum pipe 57. Layers 54 and 55 correspond to layers 49-53 according to FIG. 6, film 56 corresponds to films 29 and 31 according to FIG. 13, and line 57 corresponds to lines 41-44 according to FIG. 6. If the thickness of the Silicon oxide film 56 is small, a capacitor arrangement consisting of the line 57 , the film 56 and electrical charges 58 is formed so that charges 58 in the chip 6 between the layers 54 and 55 due to an electrical potential in the Line 57 are collected. As a result, layers 54 and 55 would be undesirably shorted by charges 58 . In this exemplary embodiment, no electrical charges accumulate, since the total thickness (= 8500 Å) of films 29 and 31 is considerably large, so that a short-circuit effect between layers 49-53 is avoided.

In addition, the sensor 10 A is minimally, if at all, influenced by the voltage in the connection or the voltage generated by the openings 5 .

Second embodiment

FIGS. 17 and 18 show a semiconductor acceleration sensor 20 A, according to a second embodiment. Sensor 20 A is substantially similar to sensor 10 A with the exception of the changed features described below. Identical reference symbols in the corresponding figures designate similar elements.

In the sensor 10 A, the mass 10 is supported by two lateral parts 9 B and 9 C. However, the mass 10 can also be supported by only the central part 9 A, as shown in FIG. 17. This type of sensor is commonly referred to as a "cantilever type sensor". The central region 9 has three parts, the central part 9 A and two generally identical and symmetrically arranged lateral parts 9 B and 9 C. Both lateral parts 9 B and 9 C are connected to the edge region 8 A. The flexible web 14 extends from the central part 9 A and supports one side of the mass 10 . Only a gap 12 is formed within the central area 9 .

Third embodiment

Fig. 19 shows a further semiconductor acceleration sensor 30 A according to a third embodiment, which has two identical generally central portions 9, the mass 10 are arranged symmetrically with respect to.

The two central areas 9 are connected to the edge area 8 . The flexible webs 14-17 extend from the central areas 9 to the mass 10 such that two flexible webs are connected to one side of the mass 10 to support the mass.

Fourth embodiment

Fig. 20 shows another semiconductor acceleration sensor 40 A, according to a fourth embodiment, which is similar to the third embodiment, with the exception that no recesses 12 a and 12 b are formed.

The flexible webs 14 and 16 extend away from the central area 9 . The mass 10 is supported by the flexible webs 14 and 16 .

Fifth embodiment

Fig. 21 shows a further semiconductor acceleration sensor 50 A in accordance with a fifth embodiment.

The central area 9 has four parts. Two of the four parts are connected to the edge area 8 . Another part he stretches from the edges of the two parts and connects them together. The other part extends from the middle of the two parts and connects them together. Each of the flexible webs 14-17 extends from the parts of the area 9th The mass 10 is supported by the flexible webs 14-17 on its four sides.

Sixth and seventh embodiment

According to the arrangement of the area 9 shown in FIG. 4, the area 9 can be deflected in the Y direction according to FIG. 4, since the area 9 expands or contracts, in accordance with the change in the ambient temperature. In this case, the flexible webs 15 and 17 receive a greater tension than the flexible webs 14 and 16 due to the deflection of the region 9 . It follows that the Gleichge weight of the resistance of the third circuit is lost. This problem is avoided by the sixth and seventh exemplary embodiments.

Fig. 22 shows another semiconductor acceleration sensor 60 A according to the sixth embodiment.

The central area 9 has four parts and is of quadratic shape. One of the four parts is connected to the edge area 8 via the connecting part 13 . The flexible webs 14-17 extend from the two parts of the area 9 . The mass 10 is supported by the flexible webs 14-17 .

Fig. 23 shows another semiconductor acceleration sensor 70 A according to the seventh embodiment.

The central area 9 has four parts and is of quadratic shape. Two of the four parts are connected to the edge area 8 via the connecting parts 13 . The flexible webs 14-17 extend from the other two parts of the loading area 9th The mass 10 is supported by the flexible webs 14-17 .

Since the region 9 of the sixth and seventh exemplary embodiments has a square shape, the above-mentioned mechanical stress influences in the same way each of the flexible webs 14-17 . As a result, there is no loss of balance in the resistance of the bridge circuit. In addition, in the seventh embodiment, all transmission paths R 1- R 4 are the same in length. As a result, the tension in the connection affects the flexible webs 14-17 to the same extent.

Claims (22)

1. A semiconductor strain sensor which has:
One Base;
an edge portion connected to the base, wherein mechanical stress is generated in the connection at a connecting portion between the base and the edge portion;
a central area extending from the edge area;
a flexible web extending from the central region and having a tension sensing element which changes its electrical properties when a mechanical stress is applied thereto, the thickness of the flexible web being smaller than the thickness of the central region, and
wherein a transmission path over which the voltage in the connection is transmitted from the connection portion to the voltage detection element is provided. 2. Semiconductor strain sensor according to claim 1, characterized characterized in that the voltage detection element a represents piezoresistive layer.   3. A semiconductor strain sensor according to claim 1, characterized characterized that the edge area, the central area and the flexible bridge made from a single semiconductor substrate are made. 4. A semiconductor strain sensor according to claim 3, characterized characterized in that the semiconductor substrate is a sili Zium substrate represents. 5. A semiconductor strain sensor according to claim 3, characterized characterized in that the thermal expansion coefficient ent of the semiconductor substrate is different from the coefficient of thermal expansion of the base. 6. The semiconductor strain sensor according to claim 5, characterized characterized in that the base is made of glass. 7. A semiconductor strain sensor according to claim 4, characterized characterized in that the thickness of the flexible web is smaller than 15 µm. 8. The semiconductor strain sensor according to claim 1, characterized characterized in that the edge area is rectangular Has shape. 9. A semiconductor strain sensor according to claim 1, characterized characterized in that the longitudinal direction of the Central area is different from longitudinal Direction of the flexible bridge. 10. A semiconductor strain sensor according to claim 1, characterized characterized in that the central area at least two Has parts, at least one of the two Parts connected to the edge area.   11. A semiconductor strain sensor according to claim 10, characterized characterized in that the central area has two parts points and ver these two parts with the edge area are bound. 12. The semiconductor strain sensor of claim 11, further comprising:
a mass supported by the flexible web;
a plurality of the flexible webs, wherein at least one of the flexible webs is arranged between one of the two parts and the mass and the other or the other flexible webs are arranged between the other of the two parts and the mass. 13. The semiconductor strain sensor according to claim 10, characterized characterized in that the central area consists of three parts is composed, with two of the three parts of Extend the edges of the other of the three parts and the longitudinal direction of the two parts different is to the longitudinal direction of the other part. 14. The semiconductor strain sensor of claim 13, further comprising:
a mass supported by the flexible web;
a plurality of the flexible webs, the other part being connected to the edge region via a connecting part and at least one of the flexible webs being arranged between one of the two parts and the mass, and the other flexible webs between the other of the two parts and the mass are arranged. 15. The semiconductor strain sensor according to claim 13, characterized is characterized by a mass by the flexible Is supported webs, the two parts with the Edge area are connected, and the flexible web between the other part and the mass is arranged. 16. A semiconductor strain sensor according to claim 10, characterized characterized in that the central area consists of four parts is composed, and these four parts a right kige shape. 17. The semiconductor strain sensor as claimed in claim 16, characterized by:
a mass supported by the flexible web;
a plurality of the flexible webs, one of the four parts being connected to the edge region via a connecting part. 18. A semiconductor strain sensor according to claim 16, characterized characterized that two of the four parts with the Randbe are richly connected. 19. The semiconductor strain sensor according to claim 18, characterized by:
a mass supported by the flexible web;
a plurality of the flexible webs, one of the two parts being arranged opposite the other of the two parts, and the flexible web being arranged between the other two of the four parts and the mass. 20. A semiconductor strain sensor, which has:
One Base;
an edge portion connected to the base, wherein stress is generated in the joint at a connection portion between the base and the edge portion;
a central area extending from the edge area; and
a flexible land extending from the central region and having a tension sensing element which changes its electrical properties when a mechanical stress is applied, the thickness of the flexible land being smaller than the thickness of the central region, and the longitudinal direction of the flexible land is different from the longitudinal direction of the central area. 21. A semiconductor strain sensor, which has:
One Base;
an edge portion connected to the base, wherein stress is generated in the joint at a connection portion between the base and the edge portion;
a central region which extends from the edge region, the central region being composed of at least two parts, and the longitudinal direction of one of the two parts being different from the longitudinal direction of the other of the two parts;
a flexible web that extends from the central region and has a voltage detection element that changes its electrical properties when a mechanical voltage is applied, wherein the thickness of the flexible web is smaller than the thickness of the central region. 22. A semiconductor strain sensor, which has:
One Base;
a chip connected to the base with an edge area and a central area;
wherein the edge region and the central region are separated by a gap and are connected to one another via a connecting part;
wherein the central area has a device for detecting mechanical tension applied to the sensor; and
a transmission path for minimizing the influence of a voltage in the connection on the detection device, wherein the transmission path is arranged bendable at predetermined locations to weaken the mechanical tension in the connection before it reaches the detection device.