JP2012137312A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor equipped with a magnetism sensing part and a trimming part enabling adjustment of the magnetic sensitivity and resistance.SOLUTION: The magnetic sensor includes a magnetism sensing part 21 having a cross-shaped pattern composed of a compound semiconductor provided on a substrate 26. Trimming parts 23a, 23b having the compound semiconductor are serially connected to at least one terminal 21a and one terminal 21d of input terminals 21a, 21b and output terminals 21c, 21d via a connection electrode 24. The adjustment of the magnetic sensitivity in constant voltage driving is made possible by laser-trimming the trimming part 23a of the input terminal side serially connected to the magnetism sensing part 21 via the connection terminal 24 while performing wafer probing, and the adjustment of output resistance is made possible by similarly trimming the trimming part 23b of the output terminal side.

Description

  The present invention relates to a magnetic sensor including a magnetic sensing portion made of a compound semiconductor, and more particularly to a magnetic sensor including a magnetic sensing portion and a trimming portion that enables adjustment of magnetic sensitivity and resistance.

  In general, magnetic sensors are widely applied to current detection elements, position detection elements, and the like. In recent years, the accuracy has increased, and variations in the characteristics (magnetic sensitivity and unbalanced voltage) of magnetic sensors have been reduced. The demand is getting stronger. Normally, the characteristics of the sensor module on which the magnetic sensor is mounted are adjusted by a variable resistor or the like, or the output is amplified by an amplifier, but if the variation of the magnetic sensor on the wafer can be reduced, Individual adjustment on the sensor module circuit is simplified, and the cost and size can be reduced.

  FIGS. 1A and 1B are configuration diagrams for explaining a conventional magnetic sensor. FIG. 1A is a top view, and FIG. 1B is a line IB-IB ′ in FIG. FIG. 2 is a circuit diagram showing an equivalent circuit of FIG. In the figure, reference numeral 1 denotes a magnetic sensing part, 1a and 1b denote input terminals of the magnetic sensing part, 1c and 1d denote output terminals of the magnetic sensing part, 2 denotes a bonding electrode pad, 5 denotes a protective layer, and 6 denotes a substrate.

  As shown in FIGS. 1A and 1B, the conventional magnetic sensor has a cross-shaped pattern of the magnetic sensing portion 1 made of a compound semiconductor provided on a substrate 6. As shown in FIG. 2, the magnetic sensing unit 1 constitutes a bridge circuit and includes input terminals 1a and 1b and output terminals 1c and 1d. Bonding electrode pads 2 are connected to these input terminals 1a and 1b and output terminals 1c and 1d, respectively. A protective layer 5 is provided on the magnetic sensitive part 1.

  Since the conventional magnetic sensor having such a configuration does not have a trimming unit, a constant voltage Vin is applied as it is between the input terminals 1a and 1b of the magnetic sensing unit 1 as shown in FIG. Is done. The magnetic sensitivity of the magnetic sensor in the constant voltage drive is determined by the mobility of the compound semiconductor, the shape (the ratio between the length and the width) of the magnetosensitive part 1 and the input voltage Vin, so that the element is between elements (in the wafer surface and between the wafers). The variation in the mobility of the semiconductor layer and the shape of the magnetic sensing portion in the above becomes the variation in the magnetic sensitivity in the constant voltage drive as it is, so that the magnetic sensitivity in the constant voltage drive cannot be adjusted.

  As a method for reducing such characteristic variation of the magnetic sensor, for example, it is known to perform trimming as shown in Patent Documents 1 and 2 on the magnetic sensor. The thing of patent document 1 is related with a Hall element with a small unbalanced voltage. While measuring the voltage between Hall voltage terminals, the method of putting a slit by the required amount in a Hall voltage terminal and a mounting part, and a magnetosensitive The method of metal-plating the part is adopted, and the offset voltage is adjusted by such a method.

  FIG. 3 is a circuit diagram showing an equivalent circuit of the magnetic sensor described in Patent Document 1 described above. In the figure, reference numerals 11a and 11b denote input terminals of the magnetic sensing unit, and 11c and 11d denote output terminals of the magnetic sensing unit. Show. This Patent Document 1 describes that the offset voltage can be adjusted by trimming the magnetic sensitive part. However, since the voltage Vin applied to the magnetic sensitive part (bridge circuit) is constant, the constant voltage driving is performed. The magnetic sensitivity cannot be adjusted.

  Further, the one described in Patent Document 2 relates to a magnetic sensor used for a speed sensor or a magnetic encoder, and trimming is performed by irradiating a resistor that constitutes a bridge in a magnetoresistive element to adjust an offset voltage. Yes.

  As described above, in any of the methods described in Patent Documents 1 and 2 described above, the offset voltage can be adjusted on the wafer, but the sensitivity cannot be adjusted.

  Further, the magnetic sensor is often used as a magnetic detection device constituted by a combination of an adjustment circuit including a variable resistor and an amplifier, and in this case, the magnetic sensor is a part of a circuit forming such a device. It becomes.

  FIG. 4 is a circuit diagram of a conventional magnetic detection device including a magnetic sensor and an amplifier, and is an example of a magnetic detection device circuit for the purpose of connecting the magnetic sensor to the amplifier and amplifying the output. In the figure, Rin and Rout indicate the input resistance and output resistance of the magnetic sensor, and Ra and Rb indicate the input resistance and feedback resistance of the amplifier, respectively. In the amplifier shown in this circuit diagram, it is known that the output of the entire device is Rb / (Ra + Rout / 2) times the output of the magnetic sensor alone.

  That is, it can be seen that the output resistance of the magnetic sensor is a parameter of the gain of the amplifier, and the output resistance of the magnetic sensor affects the output variation of the entire device. Therefore, the output variation of the entire device can be reduced by adjusting the sensitivity of the magnetic sensor and the output resistance of the magnetic sensor that is a part of the circuit.

JP-A-55-134992 JP-A-1-199180

  The present invention has been made in view of such a situation, and an object of the present invention is to adjust the resistance and magnetic sensitivity of a magnetic sensor on a wafer and to provide a magnetic material with small characteristic variation that is excellent in mass productivity. It is an object of the present invention to provide a magnetic detection device configured in combination with a sensor, an adjustment circuit, and an amplifier.

  The present invention has been made to achieve such an object, and the invention according to claim 1 is directed to a magnetic sensor including a magnetosensitive portion made of a compound semiconductor provided on a substrate, and the magnetosensitive portion. Includes an input terminal and an output terminal, and a trimming portion including the compound semiconductor is connected to each of the input terminal and the output terminal via a connection electrode. (Equivalent to Example 1 in FIG. 7)

  The invention according to claim 2 is the invention according to claim 1, wherein the trimming portion includes a trimming layer and a first compound semiconductor layer provided on the trimming layer, The compound semiconductor layer is made of a material through which the trimming laser beam is transmitted. (Corresponding to Example 2 in FIG. 8)

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the trimming part includes a trimming layer and a second compound semiconductor layer provided under the trimming layer, The second compound semiconductor layer is a material through which a trimming laser beam is transmitted. (Corresponding to Example 3 in FIG. 14)

  The invention according to claim 4 is the invention according to claim 3, wherein the first and second compound semiconductor layers are made of an AlGaAsSb layer, and the trimming layer is made of an InAs layer.

  According to the present invention, the trimming portion having the same compound semiconductor as the magnetic sensitive portion is connected to the input terminal and the output terminal of the magnetic sensitive portion of the magnetic sensor via the connection electrode, and wafer probing (electrical inspection) is performed. However, by changing the resistance value of the trimming part using laser trimming, it is possible to adjust the sensitivity connected to the input terminal side trimming part and the resistance connected to the circuit outside the magnetic sensor at the output side trimming part, It is possible to provide a magnetic sensor that is excellent in mass productivity and has a small characteristic variation, and a magnetic detection device that is configured in combination with an adjustment circuit and an amplifier.

It is a block diagram for demonstrating the conventional magnetic sensor, (a) is a top view, (b) is IB-IB 'sectional view taken on the line in Fig.1 (a). It is a circuit diagram which shows the equivalent circuit of Fig.1 (a). 10 is a circuit diagram showing an equivalent circuit of a magnetic sensor described in Patent Document 1. FIG. It is a circuit diagram of the magnetic detection device comprised by the conventional magnetic sensor and amplifier. BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram for demonstrating embodiment of the magnetic sensor which concerns on this invention, (a) is a top view, (b) is the IIB-IIB 'line sectional drawing in Fig.5 (a). It is a circuit diagram which shows the equivalent circuit of Fig.5 (a). It is a block diagram which shows Example 1 of the board | substrate and trimming part in the magnetic sensor of this invention. It is a block diagram which shows Example 2 of the trimming part provided with the board | substrate and the 1st compound semiconductor layer in the magnetic sensor of this invention. FIG. 4 is a conceptual diagram of a cross section of a trimmed InAs layer, where (a) shows the case of laser trimming at a low power, and (b) shows the case of laser trimming at a high power. FIG. 4B is another conceptual diagram of a trimmed InAs layer cross section, where (a) shows the case of laser trimming at low power, and (b) shows the case of laser trimming at high power. It is a figure which shows the relationship between a trimming part cut rate and the magnetic sensitivity change rate in a constant voltage drive. It is a figure which shows the ratio of a cut width and a magnetic sensing part width. It is a figure which shows the relationship between a trimming cut rate and a resistance change rate. It is a block diagram which shows Example 3 of the trimming part provided with the board | substrate and the 1st and 2nd compound semiconductor layer in the magnetic sensor of this invention. It is a figure which shows a mode that the whole InAs layer fuse | melts and solidifies even with a low power laser beam. It is a figure which shows the relationship between a trimming part cut rate and the magnetic sensitivity change rate in a constant voltage drive. It is a figure which shows the relationship between a trimming cut rate and a resistance change rate. It is a block diagram which shows Example 4 in the magnetic sensor of this invention. It is a circuit diagram which shows the equivalent circuit of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
5A and 5B are configuration diagrams for explaining an embodiment of the magnetic sensor according to the present invention, FIG. 5A is a top view, and FIG. 5B is IIB in FIG. 5A. FIG. 6 is a circuit diagram showing an equivalent circuit of FIG. 5A. In the figure, reference numeral 21 is a magnetic sensing part, 21a and 21b are input terminals of the magnetic sensing part, 21c and 21d are output terminals of the magnetic sensing part, 22 is a bonding electrode pad, 23 (23a and 23b) is a trimming part, and 24 is a connection. An electrode, 25 is a protective layer, and 26 is a GaAs substrate.

  The magnetic sensor of the present invention includes a cross-shaped pattern of the magnetic sensitive part 21 made of a compound semiconductor provided on a GaAs substrate 26. The magnetic sensing unit 21 includes input terminals 21a and 21b and output terminals 21c and 21d, and is connected to at least one input terminal 21a of the input terminals 21a and 21b and at least one output terminal 21d of the output terminals 21c and 21d. Trimming portions 23 a and 23 b each having a compound semiconductor are connected in series via a connection electrode 24.

  With this configuration, the trimming unit 23a and the magnetic sensing unit 21 are connected in series via the connection electrode 24. For example, by adjusting the resistance value R1 of the trimming unit 23a on the input terminal side by laser trimming, Although the voltage applied to the sensor is constant, the voltage applied to the magnetic sensing unit 21 is arbitrarily adjusted by changing the ratio of the resistance value R between the trimming unit 23a and the magnetic sensing unit 21 connected in series. can do.

  Similarly, the resistance between the output terminals of the magnetic sensor can be arbitrarily adjusted by adjusting the resistance value R2 of the trimming portion 23b on the output terminal side by laser trimming. The sensitivity adjustment by the trimming unit 23a on the input terminal side and the resistance adjustment by the trimming unit 23b on the output terminal side are independent from each other.

  In other words, when measuring electrical characteristics such as magnetic sensitivity in constant voltage driving by wafer probing, magnetic properties due to mobility and the shape of the magnetic sensing portion 21 are monitored while monitoring magnetic sensitivity in constant voltage driving and resistance between output terminals. It becomes possible to adjust the characteristic variation between sensors to a constant value. It is possible to adjust the sensitivity variation by changing the resistance value R1 of the trimming unit 23a on the input terminal side, and further adjust the resistance variation by changing the resistance value R2 of the trimming unit 23b on the output terminal side. .

  As described above, when the equivalent circuit of the conventional magnetic sensor shown in FIG. 3 is compared with the equivalent circuit of the magnetic sensor of the present invention shown in FIG. The voltage applied to the circuit) 1 is constant, so that the magnetic sensitivity in the constant voltage drive cannot be adjusted. On the other hand, in the present invention, the voltage applied to the magnetic sensing part (bridge circuit) 21 is The resistance value R1 of the trimming unit 23a on the input side can be arbitrarily adjusted, and the resistance between the output terminals can be arbitrarily adjusted by changing the resistance value R2 of the trimming unit 23b on the output side. The difference is that it can.

  In FIG. 5A, the shape of the magnetic sensing part of the magnetic sensor is shown in a cross shape, but the effect of adjusting the characteristic variation by laser trimming is the same regardless of the shape of the magnetic sensing part.

  FIG. 7 is a block diagram showing Example 1 of the substrate and the trimming portion in the magnetic sensor of the present invention, in which the reference numeral 26 denotes a GaAs substrate, and 28 denotes an InAs layer (trimming layer). Note that the InAs layer (trimming layer) 28 corresponds to the trimming portion 23a or 23b in FIGS.

  The material of the trimming portions 23a and 23b of the present invention is not particularly limited as long as it is the same compound semiconductor as that of the magnetic sensitive portion 21. A method of forming a compound semiconductor thin film on a substrate 26 such as GaAs or Si by MBE (molecular beam epitaxy) method or MOCVD (metal organic chemical vapor deposition) method, or a compound semiconductor GaAs substrate, for example, Si on a GaAs substrate There is a method in which a trimming portion is formed by ion-implanting and the like, and then activation annealing.

  When the trimming portions 23a and 23b covered with the protective layer 25 such as silicon oxide or silicon nitride are irradiated with laser light, the laser light passes through the protective layer 25 and is absorbed by the trimming layer 28. The resistance value R changes by melting and solidifying. In the present invention, since the trimming layer material is a compound semiconductor, unlike the general trimming method in which the metal material is evaporated to remove the link, damage to the protective layer 25 can be achieved without completely removing the trimming layer. Laser trimming can be performed while suppressing.

  The protective layer 25 has a role of suppressing the corrosion of the compound semiconductor layer due to an external atmosphere such as moisture, and is necessary to obtain a highly reliable device. Although it is not impossible to form the protective layer 25 after the laser trimming, the characteristics adjusted by the laser trimming may be shifted due to the thermal history in the process of forming the protective layer 25, resulting in characteristic variations. Not suitable for reduction, because laser trimming is performed in the middle of the process, the number of probing increases as compared with the case of laser trimming at the time of wafer inspection after the completion of the device, and As etc. when laser trimming is performed without the protective layer 25 Since it may be scattered and is not suitable for the environment, it is preferable to perform laser trimming with the protective layer 25 formed, that is, after the device is completed.

  The layer structure of the trimming portions 23a and 23b may be a single layer structure of a compound semiconductor or a laminated structure (multilayer structure), and is not particularly limited. Is preferably provided with a first compound semiconductor layer through which the trimming laser beam is transmitted (see Example 2 described later). It is further preferable to provide a second compound semiconductor layer through which the trimming laser beam is transmitted below the trimming layer in which the trimming laser beam is absorbed (see Example 3 described later).

  FIG. 8 is a block diagram showing Example 2 of the substrate and the trimming unit in the magnetic sensor of the present invention, in which reference numeral 26 denotes a GaAs substrate (the same reference numerals as those in FIG. 7) and 38 denotes an InAs layer (trimming). Layers 39 and 39 are AlGaAsSb layers (first compound semiconductor layers). Note that the InAs layer (trimming layer) 38 and the AlGaAsSb layer (first compound semiconductor layer) 39 correspond to the trimming portion 23 (23a, 23b) in FIGS.

  When the trimming portions 23 a and 23 b covered with the protective layer 25 are irradiated with laser light, the laser light passes through the protective layer 25 and the first compound semiconductor layer 39 and is absorbed by the trimming layer 38. As the material melts and solidifies, the resistance value R changes. When the protective layer 25 and the trimming layer 38 are in contact with each other, stress is applied to the protective layer 25 when the trimming layer 38 is melted or solidified, but the first compound semiconductor layer 39 that transmits and does not absorb the trimming laser light is applied to the trimming layer 38. By providing between the protective layer 25 and the protective layer 25, stress on the protective layer 25 can be suppressed.

  FIGS. 9A and 9B are conceptual diagrams (Example 1) of a cross section of a trimmed InAs layer. FIG. 9A is a case of laser trimming at low power, and FIG. The case of laser trimming at high power is shown. FIGS. 10A and 10B are other conceptual views (Example 2) of the trimmed InAs layer cross section. FIG. 10A shows the case of laser trimming at low power in FIG. b) shows the case of laser trimming at high power.

  In laser trimming at low power, the resistance can be changed with almost no stress on the protective layer in any structure, but it is high to melt and solidify to a deeper part of the InAs layer and increase the resistance change rate. When laser trimming is performed with power, in the structure shown in FIGS. 9A and 9B, the portion to be melted and solidified is in contact with the protective layer, so that the stress on the protective layer is large and cracks occur and the quality deteriorates. There is also. On the other hand, in the structure of FIGS. 10A and 10B, since the first compound semiconductor layer exists between the protective layer and the trimming layer, the stress on the protective layer is reduced even at high power. Trimming is possible. The first compound semiconductor layer has a forbidden band width that does not absorb laser light, and is a material having a sufficiently high resistance to the trimming layer.

  FIG. 11 is a diagram showing the relationship between the trimming portion cut rate and the magnetic sensitivity change rate in constant voltage driving. Here, the cut rate indicates the ratio between the cut width and the magnetic sensitive portion width shown in FIG.

  The magnetic sensitivity change rate in constant voltage drive varies depending on the laser output, and the magnetic sensitivity adjustment range (magnetic sensitivity change rate in constant voltage drive) in the range of the cut rate of 0 to 75% is 5% when the laser output is 0.07 μJ, 0 It was 17% at 30 μJ.

  FIG. 13 is a diagram showing the relationship between the trimming cut rate and the resistance change rate in the present invention. The resistance adjustment width (resistance change rate) in the range of the cut rate of 0 to 75% was 5% at a laser output of 0.07 μJ and 18% at 0.30 μJ.

  FIG. 14 is a block diagram showing Embodiment 3 of the substrate and trimming portion in the magnetic sensor of the present invention, in which the reference numeral 26 denotes a GaAs substrate (the same reference numerals as those in FIG. 7), and 47 denotes a lower AlGaAsSb layer ( (Second compound semiconductor layer), 48 is an InAs layer (trimming layer), and 49 is an upper AlGaAsSb layer (first compound semiconductor layer). Note that the lower AlGaAsSb layer (second compound semiconductor layer) 47, the InAs layer (trimming layer) 48, and the upper AlGaAsSb layer (first compound semiconductor layer) 49 are the trimming portion 23 in FIGS. 5 (a) and 5 (b). (23a, 23b). In order to prevent surface oxidation of the upper AlGaAsSb layer, it is preferable in terms of quality to further form a GaAs layer thereon.

  The second compound semiconductor layer 47 transmits the trimming laser beam, that is, by selecting a material that is not absorbed, the laser beam is absorbed only by the trimming layer 48. Therefore, the trimming can be efficiently performed with the low-power laser beam. can do. Further, as the material of the second compound semiconductor layer 47, it is preferable to select a material having a lattice constant close to that of the trimming layer 48.

This will be described below using a specific example.
When the InAs layer is directly formed on the GaAs substrate 26 as the trimming layer 48, the lattice constants of GaAs and InAs are greatly different. Therefore, in order to obtain a high-quality InAs layer, it is necessary to form 300 nm or more. In order to increase the resistance by laser trimming the whole, a high-power laser beam is required. On the other hand, an AlGaAsSb layer having a lattice constant close to that of InAs is formed on the GaAs substrate 26, and then an InAs layer is formed thereon, thereby forming a thin but high quality trimming layer (InAs layer) 48. be able to. In order to fabricate a high-performance magnetic sensor in a structure having AlGaAsSb layers close to the lattice constant above and below the InAs layer, and to perform laser trimming at low power without damaging the protective layer, the InAs layer The thickness of is preferably 1 to 200 nm, and more preferably 30 to 100 nm for production.

  FIG. 15 is a diagram showing how the entire InAs layer is melted and solidified even with a low-power laser beam. Compared with the case where the trimming layer 48 is directly formed on the GaAs substrate 26, the InAs layer can be made thinner. As shown in FIG. 15, the entire InAs layer is melted and solidified even with a low-power laser beam. The resistance value of the trimming part can be adjusted efficiently. If laser trimming can be performed with low power, the area to be melted and solidified can be reduced, and the length of the trimming portion can be shortened, so that the chip size can be reduced and the cost is advantageous.

  FIG. 16 is a diagram showing the relationship between the trimming portion cut rate and the magnetic sensitivity change rate in constant voltage driving. The magnetic sensitivity adjustment range (magnetic sensitivity change rate in constant voltage driving) in the range of the cut rate of 0 to 75% was 35% at a laser output of 0.07 μJ. It can be seen that the magnetic sensitivity adjustment range is wider than in the case where the InAs film is thick (Example 2). In other words, characteristic adjustment is possible with a short cut length. Therefore, a laminated structure including compound semiconductor layers that transmit the trimming laser light and have a lattice constant close to that of the trimming layer above and below the trimming layer is suitable as the structure of the trimming portion.

  FIG. 17 is a diagram illustrating the relationship between the trimming cut rate and the resistance change rate. The resistance adjustment width (resistance change rate) in the range of the cut rate of 0 to 75% was 37% at a laser output of 0.07 μJ.

  Hereinafter, a compound semiconductor multilayer structure formed by the MBE method in the present invention will be described based on FIG. 14 described above. The compound semiconductor laminated structures 47, 48, 49 are sequentially formed on a GaAs substrate 26 in order of a 500 nm lower AlGaAsSb layer 47, a 50 nm InAs layer 48, a 50 nm upper AlGaAsSb layer 49, and an AlGaAsSb layer thereon. A 10 nm GaAs layer is formed as an antioxidant layer. Thereafter, by using a process technique such as lithography and etching, the magnetic sensor shown in FIGS. 5A and 5B, in which the compound semiconductor multilayer structures 47, 48, and 49 are used as the magnetic sensitive portion 21 and the trimming portions 23a and 23b. Was made. The forbidden band widths of the constituent materials of the compound semiconductor laminated structure are 1.3 eV for the AlGaAsSb layers 47 and 49, 0.36 eV for the InAs layer 48, and 1.43 eV for the GaAs layer.

Next, a trimming method for this magnetic sensor will be described.
In order to adjust the magnetic sensitivity in the constant voltage drive, a wafer trimming apparatus incorporating an electromagnetic coil was used so that a magnetic field could be applied to the magnetic sensor on the wafer. As a trimming laser, a YAG laser having a wavelength of 1064 nm (1.17 eV) that is transmitted through the GaAs layer and the AlGaAsSb layers 47 and 49 having a compound semiconductor multilayer structure and absorbed by the InAs layer 48 is used. The results of adjusting the characteristics by irradiating the trimming parts 23a and 23b with laser light while monitoring the magnetic sensitivity in the constant voltage drive will be described below.

  The magnetic sensitivity (input voltage 3 V, applied magnetic field 50 mT) in constant voltage drive before laser trimming was 120 mV on average over the entire wafer surface (50000 elements), and the standard deviation σ was 5 mV. When laser trimming was performed so that the magnetic sensitivity in driving was 105 mV, the average was 105 mV, and the standard deviation σ was 0.4 mV. When the variation in the wafer surface was expressed as <3σ / average>, the variation was improved by 1 digit or more from 12.5% to 1.1% before and after laser trimming.

  In addition, the resistance between output terminals before trimming was 930Ω on the entire wafer surface (5000 elements) and the standard deviation σ was 26Ω, while trimming so that the resistance between output terminals was 1100Ω. As a result, the average was 1100Ω and the standard deviation σ was 4.5Ω. When the variation in the wafer surface is expressed by <3σ / average>, the variation was reduced by 1/7 from 8.4% to 1.2% before and after trimming.

  As described above, the trimming portions 23a and 23b connected in series to the magnetic sensitive portion 21 via the connection electrode 24 are subjected to laser trimming while performing wafer probing (electrical inspection), thereby enabling constant voltage driving. The magnetic sensitivity and the resistance between the output terminals can be adjusted, and a magnetic sensor excellent in mass productivity and small in characteristic variation can be provided.

  18 is a block diagram showing Embodiment 4 of the magnetic sensor of the present invention, and FIG. 19 is an equivalent circuit of FIG. In the figure, reference numeral 31 denotes a magnetic sensing part, 32 denotes a bonding electrode pad, 33 (33a, 33b) denotes a trimming part, and 34 denotes a connection electrode. By connecting the trimming unit 33a in parallel to the input terminal of the magnetic sensing unit 31, the magnetic sensitivity in constant current driving can be adjusted. Also in this case, the output resistance can be adjusted by connecting the trimming portion 33b in series to the output terminal side via the connection electrode.

  The Hall element shown in FIG. 18 was fabricated with the same film structure as in Example 3. The result of adjusting the characteristics by irradiating the trimming unit 33 with laser light while monitoring the magnetic sensitivity in the constant current drive will be described below.

  The magnetic sensitivity (input current 5 mA, applied magnetic field 50 mT) in the constant current drive before laser trimming was 145 mV on the whole wafer surface (50000 elements) and the standard deviation σ was 7 mV, while the constant current When laser trimming was performed so that the magnetic sensitivity in driving was 170 mV, the average was 170 mV, and the standard deviation σ was 0.9 mV. When the variation in the wafer surface is expressed by <3σ / average>, the variation was improved by about one digit from 14.4% to 1.6% before and after laser trimming.

  Also in the present embodiment, the output resistance variation can be reduced independently of the magnetic sensitivity that can be adjusted by the trimming section on the input terminal side by laser trimming the trimming section on the output terminal side as in the third embodiment.

  As described above, the constant current sensitivity can be adjusted by performing laser trimming while performing wafer probing (electrical inspection) on the trimming portion 33a connected in parallel to the magnetic sensing portion 31, thereby improving mass productivity. An excellent magnetic sensor with small characteristic variation can be provided.

DESCRIPTION OF SYMBOLS 1 Magnetic-sensitive part 1a, 1b Magnetic-sensitive part input terminal 1c, 1d Magnetic-sensitive part output terminal 2 Bonding electrode pad 5 Protective layer 6 Substrate 11a, 11b Magnetic-sensitive part input terminal 11c, 11d Magnetic-sensitive part output terminal 21 , 31 Magnetic sensing portions 21a, 21b Magnetic sensing device input terminals 21c, 21d Magnetic sensing device output terminals 22, 32 Bonding electrode pads 23a, 23b, 33a, 33b Trimming portion 24, 34 Connection electrode 25 Protective layer 26 GaAs substrate 28 , 38, 48 InAs layer (trimming layer)
39 AlGaAsSb layer (first compound semiconductor layer)
47 Lower AlGaAsSb layer (second compound semiconductor layer)
49 Upper AlGaAsSb layer (first compound semiconductor layer)

Claims (4)

In a magnetic sensor having a magnetosensitive part made of a compound semiconductor provided on a substrate,
The magnetic sensing part includes an input terminal and an output terminal, and a trimming part having the compound semiconductor is connected to both the input terminal and the output terminal via a connection electrode. Sensor.   The trimming unit includes a trimming layer and a first compound semiconductor layer provided on the trimming layer, and the first compound semiconductor layer is a material that transmits a trimming laser beam. The magnetic sensor according to claim 1.   The trimming unit includes a trimming layer and a second compound semiconductor layer provided under the trimming layer, and the second compound semiconductor layer is a material that transmits a trimming laser beam. The magnetic sensor according to claim 1 or 2.   4. The magnetic sensor according to claim 3, wherein the first and second compound semiconductor layers are made of AlGaAsSb layers, and the trimming layer is made of an InAs layer.

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