JPH1096743A - Semiconductor sensor and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detecting accuracy at a low price, without improving working accuracy of individual parts. SOLUTION: A sensor element 23, a regulating IC 24 having PROM to memory data for regulating output characteristic, and digital regulating input electrodes 25 are provided on a substrate 22, and a prober 26 is brought in contact with the digital regulating input electrode 25 in a state of fixing the substrate 22 to a housing 21, so as to write in PROM by digital trimming.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor sensor using a semiconductor for a sensor element, such as an acceleration sensor or a stress sensor, and a method for manufacturing characteristics of the semiconductor sensor.

[0002]

2. Description of the Related Art FIGS.
FIG. 2 is a diagram showing a conventional acceleration sensor disclosed in Japanese Patent No. 21164. First, in FIG. 10 showing the sensor element, the weight 1 is attached to the end of the silicon plate 2,
It moves up and down due to acceleration. Four gauge resistors are formed in a Wheatstone bridge shape in the thin portion 2 in which a part of the silicon plate 2 is thinned. Lead 5 is a gauge resistor 4
Is connected to an external lead 6 to transmit an output signal to the outside. The sensor element 7 is constituted by these members.

FIG. 11 shows an amplification correction circuit board 8 on which a circuit for correcting and amplifying an output signal from the sensor element 7 is formed, and a plurality of terminals 9 for connection to the outside are provided.

FIG. 12 is a side sectional view of the acceleration sensor 10,
13 is a plan view showing the base 11 of FIG. 12, FIG. 14 is an exploded perspective view of FIG. 12, and FIG. 15 is an explanatory view showing a state where the acceleration sensor of FIG. The sensor element 7 shown in FIG. 10 and the amplification correction circuit board 8 shown in FIG. Parent board 1
2 is attached to the mother board attaching portion 14 of the base 11 by screwing the screw 13 into the screw hole 15. The output signal of the acceleration sensor 10 is output from the connector 16 to the outside. The connector 16 is provided with a terminal 17. The acceleration sensor 10 is fixed to an external structure (not shown) or the like using the mounting hole 18. Further, in FIG. 15, y represents the distance between the seating surface 19 of the base 11 and the parent substrate 12, and x represents the dimension when both parallelisms are shifted.

Next, the operation will be described. For example, FIG.
As shown in FIG. 6A, assuming that the acceleration sensor 10 is mounted horizontally on a measured object (not shown) such as an automobile with the seat surface 19 facing down, the weight 1 has the weight shown in FIG. ² is applied in the direction of arrow A (+9.8 m / s ² ), and FIG.
In the characteristic diagram of FIG. Conversely, FIG.
When the seat 1 is mounted horizontally with the seating surface 19 facing upward as shown in FIG. 16B, a force (−9.8 m / s ² ) in the direction of arrow B shown in FIG. 1.5V from 2
Output. That is, if the mounting method is fixed, a voltage proportional to the acceleration of the object to be measured is output, and the value of the acceleration can be known.

Next, a method for adjusting the output characteristics of the conventional acceleration sensor 10 will be described. The output signal for the acceleration coming out of element 7 is very small. Therefore, it is necessary to amplify and further correct the output signal, and an amplification correction circuit board 8 is required. The object to be corrected includes an offset, a span and its temperature characteristic. For example, in a normal semiconductor sensor, if the input is 0, the output should be 0. However, in practice, a certain value often appears due to a fabrication error or the like, and this is called an offset. The same applies to the case of the acceleration sensor 10 described above, and correction (adjustment) for the offset is required.

In FIG. 2, while the output value when the weight 1 is in the vertical state is 3.1 V before correction, by performing offset adjustment, an ideal value, in this case, 2.5 V, is obtained.
It is corrected to V. That is, the amplification correction circuit board 8 is provided with a thick film resistor (not shown) for adjustment, and the conventional offset adjustment is performed by using the element 7 and the amplification correction circuit board 8.
This is performed by performing laser trimming on the thick film resistor in a state where only the master substrate 12 is combined.

[0008]

In the conventional acceleration sensor 10 configured as described above, the offset adjustment is performed in a state where only the element 7 and the amplification correction circuit board 8 are combined. 11, the errors such as the horizontality of the motherboard 12 and the deviation x of the parallelism of the motherboard mounting portion 14 with respect to the seating surface 19 are added as offset values, and the accuracy is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and a semiconductor sensor capable of inexpensively improving detection accuracy without improving processing accuracy of individual parts. And a method for producing the same.

[0010]

According to a first aspect of the present invention, there is provided a semiconductor sensor comprising a housing, a substrate fixed to the housing, a sensor element provided on the substrate, and a substrate. A digital memory that stores data for adjusting output characteristics and can write data by digital trimming, and includes a signal processing circuit that performs digital signal processing on an output signal from the sensor element. .

In a semiconductor sensor according to a second aspect of the present invention, a digital adjustment input electrode with which a prober of a digital adjustment input device comes into contact when performing digital trimming is provided on a substrate.

In a semiconductor sensor according to a third aspect of the present invention, the sensor element is mounted on a substrate, and an adjustment IC having a signal processing circuit is joined to the sensor element.

According to a fourth aspect of the present invention, there is provided a semiconductor sensor in which a sensor element having a movable electrode and a fixed electrode is provided on a part of a semiconductor substrate provided with a signal processing circuit in a one-chip specification. is there.

According to a fifth aspect of the present invention, in the semiconductor sensor, a plurality of sensor elements for detecting accelerations in different directions and a plurality of adjustment ICs each having a signal processing circuit corresponding to these sensor elements are provided on the same substrate. It is installed in.

A semiconductor sensor according to a sixth aspect of the present invention uses an EEPROM as a digital memory.

In a semiconductor sensor according to a seventh aspect of the present invention, a sensor element and a signal processing circuit for digitally processing an output signal from the sensor element are provided on a substrate, and the substrate is fixed to a housing. The output characteristics are adjusted by performing digital trimming in a state where is fixed to an adjustment jig and held at a predetermined angle.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a cutaway perspective view showing a main part of an acceleration sensor according to Embodiment 1 of the present invention. In the drawing, reference numeral 21 denotes a housing provided with a seating surface, a mounting hole, and a connector (not shown) for taking out signals.
Reference numeral 22 denotes a substrate fixed on the housing 21, reference numeral 23 denotes a sensor element mounted on the substrate 22, and detects acceleration. Reference numeral 24 denotes a sensor element mounted on the substrate 22, and processes a minute output signal from the sensor element 23 by digital signal processing. The adjustment IC 24 has a built-in digital memory that stores data for adjusting output characteristics and can write data by digital trimming.

Reference numeral 25 denotes an adjustment IC 2 provided on the substrate 22.
4, a plurality of digital adjustment input electrodes for digitally trimming the data of the digital memory, a prober 26 is output from a digital adjustment input device (not shown), and contacts a digital adjustment input electrode 25; Power supply, grounding and output pads provided in
Is an external connection wire for connecting each pad 27 to a connector.

Next, the operation will be described. The seat surface of the housing 21 is attached to an object to be measured such as an automobile, and a signal corresponding to the acceleration of the object to be measured is output from the sensor element 23. The operation principle of the sensor element 23 is the same as that of FIG. The detection signal from the sensor element 23 is subjected to digital signal processing by the adjustment IC 24 and output from the connector to the outside via the external connection wire 28.

Here, the procedure for assembling the acceleration sensor will be described. First, the sensor element 23 is adhered to the substrate 22 on which the adjustment IC 24 is mounted by, for example, an adhesive, and electrical connection is also performed by a lead (not shown). Then, the substrate 22 is fixed to the housing 21 with an adhesive or the like. The terminal of the connector is connected to the circuit of the board 22 by a wire 27, and the circuit on the board 22 is connected to an external circuit.

In this state, the seat surface of the housing 21 is attached and fixed to an adjustment jig (not shown). This adjusting jig has a holding portion for holding the acceleration sensor, and the gravitational acceleration on the ground acting on the acceleration sensor is +9.8 m / s ^2.
, -9.8 m / s ² , and 0 m / s
between the state where the s ² in which said holding unit is rotatable. With such an adjusting jig, the output characteristics are adjusted so that the ideal characteristics shown in FIG. 2 are obtained while measuring the output value by applying the gravitational acceleration to the acceleration sensor.

The above-described input device for digital adjustment is used for adjusting the output characteristics. That is, the prober 26 is brought into contact with the digital adjustment input electrode 25, and the digital memory in the adjustment IC 24, for example, a PROM is written by an electric signal, that is, digital trimming is performed. By such digital trimming, the output characteristic before the offset adjustment shown in FIG. 2A is adjusted to the ideal characteristic shown in B. Further, the housing 21 is configured so that the prober 26 can be brought into contact with the digital adjustment input electrode 25 after the board 22 is assembled.

According to the acceleration sensor as described above, the substrate 22 on which the sensor element 23 and the adjustment IC 24 are mounted
After fixing to the housing 21, writing to the adjustment IC 24 is performed by digital trimming and offset adjustment can be performed, so that the detection accuracy can be inexpensively improved without improving the processing accuracy of individual components. .

Although the above description has been made with respect to offset adjustment, the present invention can be applied to span and span shift adjustment. The span and the span shift adjustment are, as shown by a solid line in FIG. 3, a slope of an output (for example, 0 m / s) when an acceleration is applied from an output at an offset (0 m / s ² )
For ^two output 2.5V + 9.8m / s ² at 3.5V, -
9.8 m / s ² to obtain an output of 1.5 V) is called span adjustment, and span shift adjustment means that the slope of this output can be adjusted arbitrarily.

If a region for performing span and span shift adjustment, that is, a digital memory is provided in the adjustment IC 24 of FIG.
It is possible to perform span and span shift adjustment by digital trimming after assembling into the device. Therefore, the output can be adjusted collectively including the assembly error and the surrounding environment conditions, a highly accurate sensor can be obtained, and the apparatus can be concentrated in one place, so that the configuration can be made inexpensively.

Further, according to the configuration of FIG. 1, it is possible to arbitrarily adjust the frequency characteristic of the acceleration sensor. That is, by writing data using the PROM, the frequency characteristic of the element 23 itself can be adjusted to a predetermined frequency characteristic as shown by the solid line in FIG. Also,
Since the adjustment of the frequency characteristics is performed after the housing is assembled into the housing 21, the frequency characteristics can be adjusted collectively including the mounting error and the surrounding environmental conditions, and a highly accurate sensor can be obtained. Since it can be concentrated in one place, it can be constructed at low cost.

Embodiment 2 FIG. Next, FIG. 5 is a cutaway perspective view showing a main part of an acceleration sensor according to Embodiment 2 of the present invention, and a cross-sectional view of the acceleration sensor of FIG. In the figure,
31 is an adjustment I joined on the sensor element 23
The adjustment IC 31 incorporates a circuit IC 30 as a signal processing circuit for digitally processing an output signal from the sensor element 23. Further, the circuit IC 30 is provided with a digital memory that stores data for adjusting output characteristics and can write data by digital trimming. Further, the adjustment IC 31 is bonded to the sensor element 23 using a die bonding agent or using a low-temperature fusion bonding technique of silicon. Here, the low-temperature fusion bonding technique of silicon is used in order to prevent the circuit IC 30 from being thermally broken.

32a and 32b are sensor elements 23,
These are a plurality of bonding wires for wiring between the circuit IC 30 and the substrate 22. Further, the housing 21 and the substrate 22
Are joined with a low-stress adhesive (for example, a silicon adhesive). Further, a connector 21a is integrally formed on the housing 21, and a terminal 21b for connecting an electric signal to the outside is insert-molded on the connector 21a. And this Terminal 2
8 a and the circuit on the substrate 22 are connected by a wire 27.

In such an acceleration sensor, the circuit IC 30 is integrally provided on the sensor element 23 in addition to the same effect as in the first embodiment, so that the component mounting area on the substrate 22 is reduced, and Is possible. Further, by minimizing the distance between the sensor element 23 and the circuit IC 30, the effect of the stray capacitance inserted in parallel between them can be reduced, and the detection accuracy can be further improved.

Embodiment 3 Next, FIG. 7 is a schematic configuration diagram showing a main part of an acceleration sensor according to Embodiment 3 of the present invention. In this example, a sensor element 42 for detecting acceleration and a signal processing circuit 43 for digitally processing a signal from the sensor element 42 are provided on a silicon substrate 41 in a one-chip specification. The signal processing circuit 43 is provided with a digital memory capable of digital trimming, for example, a PROM 44 such as an EPROM as a sensor output calibration data storage area.

The sensor element 42 is formed by providing two openings 41a and 41b in the substrate 41. Further, the sensor element 42 includes two beams 4
The movable electrode 46 includes a movable electrode 46 connected to the main body of the substrate 43 via 5a and 45b, and a pair of fixed electrodes 47a and 47b opposed to both ends of the movable electrode 46.

In such an acceleration sensor, the movable electrode 46 moves in the direction of the arrow in FIG. 3 according to the acceleration applied to the object to be measured, and the size of the gap between the movable electrode 46 and the fixed electrodes 47a and 47b is reduced. Change. Thereby, the movable electrode 46
And the capacitance between the fixed electrodes 47a and 47b change,
An acceleration is detected.

In the acceleration sensor of the one-chip specification as described above, since the PROM 44 for storing data for calibrating the output characteristics is provided in the signal processing circuit 43, the offset after the assembly into the housing (not shown). Adjustment, span and span shift adjustment, frequency characteristic adjustment, and the like can be performed, and detection accuracy can be increased at low cost. Further, since the sensor element 42 and the signal processing circuit 43 are provided integrally, the component mounting area on the substrate 41 is reduced, and the size can be reduced. Furthermore, by minimizing the distance between the sensor element 42 and the signal processing circuit 43, the effect of the stray capacitance inserted in parallel between them can be reduced, and the detection accuracy can be further improved.

Embodiment 4 Although the PROM 44 is provided in the signal processing circuit 43 in the above example, an EEPROM (electrically erasable programmable ROM) 48 may be provided, for example, as shown in FIG. In this case, the data can be repeatedly rewritten by the electric signal, and readjustment to a different output value can be easily performed.

Embodiment 5 FIG. FIG. 9 is a schematic configuration diagram showing a main part of an acceleration sensor according to Embodiment 5 of the present invention. In this example, three sensor elements 51 to 53 having different directions (arrows in the drawing) of the acceleration to be detected are mounted on the same substrate 54. Further, three adjustment ICs 55 each having a signal processing circuit corresponding to each of the sensor elements 51 to 53 are also mounted on the same substrate 54.

Even in such an acceleration sensor of the multi-axial direction detection specification, offset adjustment, span and span shift adjustment, frequency characteristic adjustment, and the like can be performed after assembly into a housing (not shown). It can be inexpensively increased. In addition, the acceleration can be divided into a plurality of components and detected accurately.

In FIG. 9, the sensors 51 to 53 in each direction are shown.
And the adjustment IC 55 are mounted separately on the substrate 54,
The accelerations in a plurality of directions may be detected by one-chip specification as shown in FIGS. 7 and 8.

Although the acceleration sensor has been described in each of the above examples, the present invention can be applied to a stress sensor for detecting torque, distortion, and the like. That is, in the stress sensor, a similar effect can be obtained by performing offset adjustment, span adjustment, and the like while applying a stress to the sensor element attached and fixed to the stress generating unit and checking the output.

[0039]

As described above, according to the semiconductor sensor of the first aspect of the present invention, a signal processing circuit having a digital memory for storing data for adjusting output characteristics and writing data by digital trimming is provided on a substrate. Thus, the output characteristics can be adjusted while the substrate is fixed to the housing, and the detection accuracy can be improved at low cost without improving the processing accuracy of each component.

In the semiconductor sensor according to the second aspect of the present invention, since the digital adjustment input electrode with which the prober contacts is provided on the substrate, digital trimming can be easily performed.

In the semiconductor sensor according to the third aspect of the present invention, since the sensor element is mounted on the substrate and the adjustment IC having the signal processing circuit is bonded on the sensor element, the component mounting area on the substrate is reduced. Is possible. Further, by minimizing the distance between the sensor element and the signal processing circuit, the influence of the stray capacitance inserted in parallel between the two can be reduced, and the detection accuracy can be further improved.

In the semiconductor sensor according to the fourth aspect of the present invention, the sensor element having the movable electrode and the fixed electrode is provided in one chip on a part of the semiconductor substrate on which the signal processing circuit is provided. Since the signal processing circuit and the signal processing circuit are provided integrally, the component mounting area on the substrate can be reduced and the size can be reduced. Further, by minimizing the distance between the sensor element and the signal processing circuit, the influence of the stray capacitance inserted in parallel between the two can be reduced, and the detection accuracy can be further improved.

According to a fifth aspect of the present invention, there is provided a semiconductor sensor, comprising: a plurality of sensor elements for detecting accelerations in different directions;
Since a plurality of adjustment ICs each having a signal processing circuit corresponding to each of these sensor elements are mounted on the same substrate, acceleration can be divided into a plurality of components and detected accurately.

In the semiconductor sensor according to the sixth aspect of the present invention, since the EEPROM is used as the digital memory, the data can be repeatedly rewritten by the electric signal, and readjustment to a different output value can be easily performed. Can be.

In the semiconductor sensor according to the seventh aspect of the present invention, after the substrate is fixed to the housing, the housing is fixed to the adjustment jig and digital trimming is performed with the housing held at a predetermined angle, thereby adjusting the output characteristics. As a result, the detection accuracy can be improved at low cost without improving the processing accuracy of each component.

[Brief description of the drawings]

FIG. 1 is a cutaway perspective view showing a main part of an acceleration sensor according to Embodiment 1 of the present invention.

FIG. 2 is a relationship diagram showing an offset characteristic of an acceleration sensor.

FIG. 3 is a relationship diagram showing a span and a span shift characteristic of the acceleration sensor.

FIG. 4 is a relation diagram showing frequency characteristics of a sensor element of the acceleration sensor.

FIG. 5 is a cutaway perspective view showing a main part of an acceleration sensor according to a second embodiment of the present invention.

FIG. 6 is a sectional view of the acceleration sensor of FIG. 5;

FIG. 7 is a schematic configuration diagram showing a main part of an acceleration sensor according to a third embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a main part of an acceleration sensor according to a fourth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram showing a main part of an acceleration sensor according to a fifth embodiment of the present invention.

FIG. 10 is a perspective view showing an example of a sensor element of a conventional acceleration sensor.

FIG. 11 is a perspective view showing an example of a conventional amplification correction circuit board of an acceleration sensor.

FIG. 12 is a side sectional view of an example of a conventional acceleration sensor.

FIG. 13 is a plan view showing the base of FIG. 12;

14 is an exploded perspective view of FIG.

FIG. 15 is an explanatory diagram showing a state where the acceleration sensor of FIG. 12 is attached to an object to be measured.

16 is an explanatory diagram showing the direction of acceleration according to the mounting direction of the acceleration sensor of FIG.

[Explanation of symbols]

21 housing, 22, 41, 54 substrate, 23, 4
2, 51, 52, 53 sensor elements, 24, 31,
55 adjustment IC, 25 digital adjustment input electrode, 26
Prober, 43 signal processing circuit, 44 PROM, 46
Movable electrode, 47a, 47b Fixed electrode, 48 EEP
ROM.

Claims (7)

[Claims] 1. A housing, a board fixed to the housing, a sensor element provided on the board, and a digital memory for storing data for adjusting output characteristics provided on the board and for adjusting output characteristics. It has a digital memory that can write the data by trimming,
A signal processing circuit for digitally processing an output signal from the sensor element. 2. The semiconductor sensor according to claim 1, wherein a digital adjustment input electrode that contacts a prober of the digital adjustment input device when performing digital trimming is provided on the substrate. 3. The semiconductor sensor according to claim 2, wherein the sensor element is mounted on a substrate, and an adjustment IC having a signal processing circuit is bonded on the sensor element. 4. The semiconductor device according to claim 1, wherein a sensor element having a movable electrode and a fixed electrode is provided on a part of the semiconductor substrate provided with the signal processing circuit in a one-chip specification. Sensor. 5. A plurality of sensor elements for detecting accelerations in different directions, and a plurality of adjustment ICs each having a signal processing circuit corresponding to these sensor elements are mounted on the same substrate. Claim 1
The semiconductor sensor according to claim 4. 6. The semiconductor sensor according to claim 1, wherein the digital memory is an EEPROM. 7. A sensor element and a signal processing circuit for digitally processing an output signal from the sensor element are provided on a substrate, and the substrate is fixed to a housing, and then the housing is fixed to an adjustment jig. A method for manufacturing a semiconductor sensor, wherein output characteristics are adjusted by performing digital trimming while maintaining a predetermined angle.