JP2013201229A - Hall sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hall sensor capable of easily being manufactured and reducing off-set voltage without increasing chip size.SOLUTION: A hall sensor comprises: a magnetism reception section having a square or a cross-shaped second N-type impurity region; and control current input terminals and hall voltage output terminals of a first N-type high concentration impurity region arranged on each corners and edges and in the N-type impurity region in a depletion layer suppression layer being larger than the element.

Description

  The present invention relates to a semiconductor Hall element, and relates to a Hall sensor with high sensitivity and capable of removing an offset voltage.

  The magnetic detection principle of the Hall element will be described. When a magnetic field perpendicular to the current flowing in the material is applied, an electric field (Hall voltage) is generated in a direction perpendicular to both the current and the magnetic field.

When considering the Hall element as shown in FIG. 3, when the width W, the length L, the electron mobility μ, the applied voltage Vdd of the power source 2 for flowing current, and the applied magnetic field are B, the Hall element magnetic sensing unit 1 The Hall voltage output from the voltmeter 3 is
VH = μB (W / L) Vdd
It is expressed that the magnetic sensitivity Kh of this Hall element is
Kh = μ (W / L) Vdd
It is expressed. From this relational expression, it can be seen that one of the methods for increasing the sensitivity is to increase the W / L ratio.

  On the other hand, in an actual Hall element, an output voltage is generated even when no magnetic field is applied. The voltage output when the magnetic field is 0 is referred to as an offset voltage. The cause of the offset voltage is considered to be due to an imbalance in potential distribution inside the device such as mechanical stress applied to the device from the outside or misalignment during the manufacturing process.

In general, the offset voltage is compensated by the following method.
It is an offset cancellation circuit by spinning current as shown in FIG. The Hall element 100 has a symmetrical shape, and has four terminals T1, T2, T3, and T4 that allow a control current to flow through a pair of input terminals and obtain an output voltage from the other pair of output terminals. When one pair of terminals T1 and T2 of the Hall element is a control current input terminal, the other pair of terminals T3 and T4 is a Hall voltage output terminal. At this time, when the voltage Vin is applied to the input terminal, an output voltage Vh + Vos is generated at the output terminal. Here, Vh represents a Hall voltage proportional to the magnetic field of the Hall element, and Vos represents an offset voltage. Next, when the input voltage Vin is applied between T3 and T4 using T3 and T4 as control current output terminals and T1 and T2 as Hall voltage output terminals, a voltage −Vh + Vos is generated at the output terminal.

By subtracting the output voltage when the current flows in the above two directions, the offset voltage Vos is canceled, and an output voltage 2Vh proportional to the magnetic field can be obtained.
However, this offset cancel circuit cannot completely cancel the offset voltage. The reason will be described below.

  The Hall element is represented by an equivalent circuit shown in FIG. The Hall element is represented as a bridge circuit in which four terminals are connected by four resistors R1, R2, R3, and R4. As described above, the offset voltage is canceled by subtracting the output voltage when a current is passed in two directions.

When the voltage Vin is applied to one pair of terminals T1 and T2 of the Hall element, the Hall voltage is applied between the other pair of terminals T3 and T4.
Vouta = (R2 * R4-R1 * R3) / (R1 + R4) / (R2 + R3) * Vin
Is output. On the other hand, when the voltage Vin is applied to the terminals T3 and T4, the Hall voltage is applied to T1 and T2.
Voutb = (R1 * R3-R2 * R4) / (R3 + R4) / (R1 + R2) * Vin
Is output.
Taking the difference in output voltage in two directions,
Vouta-Voutb = (R1-R3) * (R2-R4) * (R2 * R4-R1 * R3) / (R1 + R4) / (R2 + R3) / (R3 + R4) / (R1 + R2) * Vin
It becomes. Therefore, the offset voltage can be offset canceled even when the resistors R1, R2, R3, and R4 of the equivalent circuits are different. However, when the values of the resistors R1, R2, R3, and R4 change depending on the current application direction and the applied voltage, the above equation does not hold, and therefore offset cancellation cannot be performed.

  FIG. 5 is a cross-sectional view of a general Hall element (see, for example, Patent Document 1). A peripheral portion of the N-type impurity region that becomes the Hall element magnetic sensing portion is surrounded by a P-type impurity region for isolation. When a voltage is applied to the Hall current application terminal, a depletion layer spreads at the boundary between the Hall element magnetic sensing part and its peripheral part. Since no hole current flows in the depletion layer, the hole current is suppressed and the resistance increases in the region where the depletion layer extends. The depletion layer width depends on the applied voltage. Therefore, the values of the resistances R1, R2, R3, and R4 of the equivalent circuit shown in FIG.

  There is a case where a depletion layer control electrode is arranged around the element and at the top of the element, and a method of suppressing the depletion layer by adjusting a voltage applied to each electrode is extended so that the depletion layer extends into the Hall element. (For example, refer to Patent Document 2).

International Publication No. 2007/116823 Japanese Patent Laid-Open No. 08-330646

  In the method of Patent Document 1, when a voltage is applied to the Hall element, a depletion layer spreads at the junction between the Hall element magnetic sensing part which is a thin N-type impurity region and the peripheral part and the bottom part which are P-type substrates. The depletion layer suppresses the current flowing in the Hall element, and the resistance value changes. The depletion layer width varies depending on the applied voltage and its direction. For this reason, the offset voltage cannot be removed by the spinning current by the offset cancel circuit.

In the method of Patent Document 2, the depletion layer width can be controlled by the depletion layer control electrode, and the offset voltage can be removed by using the offset cancel circuit. However, since a plurality of depletion layer control electrodes are used and a complicated control circuit is required, there is a problem that the chip size increases and the cost increases.
SUMMARY OF THE INVENTION An object of the present invention is to provide a Hall sensor in which the depletion layer width hardly changes and the offset voltage can be removed without using a complicated control circuit.

In order to solve the above problems, the present invention has the following configuration.
First, the Hall sensor is characterized in that the control current flowing in the Hall element can be separated from the junction between the Hall element magnetic sensing part, which is an N-type impurity region, and the peripheral part of the P-type substrate.

  Also, the control current input terminal of the N-type high concentration impurity region at the first N-type impurity region of the square or cross-shaped second N-type impurity region and the first N-type impurity region of the depletion layer suppression layer and at each vertex and end thereof And a hall voltage output terminal.

The Hall sensor is characterized in that the first N-type impurity region, which is a depletion layer suppression region, is 3 to 10 μm larger than the second N-type impurity region of the magnetic sensing portion and has a low impurity concentration.
In addition, the control current input terminal and the Hall voltage output terminal are arranged inside the depletion layer suppression region, and are arranged inside and separated from the boundary between the depletion layer suppression region and the P-type substrate in the periphery thereof. The hall sensor.

Further, the Hall sensor is characterized in that the P-well region and the P-type diffusion region are separated from the Hall magnetic sensing part by 5 μm or more.
Further, the Hall sensor is characterized in that the offset voltage can be removed by spinning current.

  By using the above means, the control current flowing in the Hall element can flow separately from the junction between the Hall element magnetic sensing part which is an N-type impurity region and the peripheral part of the P-type substrate. For this reason, the depletion layer is prevented from extending into the Hall element magnetic sensing portion, and the resistance between the terminals does not change depending on the applied voltage and its direction. Therefore, the offset voltage can be removed by the spinning current.

  In addition, because the depletion layer suppression region is placed under the Hall element magnetic sensing part, the resistance voltage change due to the depletion layer can be suppressed without using a depletion layer suppression electrode or a complicated circuit, eliminating the offset voltage. It is possible to reduce the chip size and the cost.

It is a figure which shows the structure of the Hall element of this invention. It is a figure for demonstrating the principle of an ideal Hall effect. It is a figure for demonstrating the removal method of the offset voltage by a spinning current. It is a figure of the equivalent circuit for demonstrating the offset voltage of a Hall element. It is a figure of the cross-sectional structure of a general Hall element. It is a figure which shows the structure of the cross-shaped Hall element of this invention.

FIG. 1 is a diagram showing the configuration of the Hall element of the present invention. The Hall element of the present invention has a magnetic sensing part composed of a square second N-type impurity region 121 having a side of 50 to 150 μm, a size larger than that of the magnetic sensing part by 3 to 10 μm, and a depth greater than that of the second N-type. Control current input terminals and holes of a depletion layer suppression region composed of a first N-type impurity region 122 having an impurity concentration lower than that of the impurity region 121, and an N-type high-concentration impurity region disposed at each vertex of the square magnetic sensing portion Voltage output terminals 11, 12, 13, and 14 are provided. The first N-type impurity region 121 of the magnetic sensing portion has a concentration between 1 × 10 ¹⁶ (atoms / cm ³ ) and 5 × 10 ¹⁶ (atoms / cm ³ ), and is a depletion layer suppression region. The concentration of the type impurity region 122 is preferably between 8 × 10 ¹⁴ (atoms / cm ³ ) and 3 × 10 ¹⁵ (atoms / cm ³ ). That is, the depletion layer suppression region has a lower impurity concentration than the magnetic sensing portion, and the depletion layer suppression region covers the side surface and bottom surface of the Hall magnetic sensing portion where the control current input terminal and the Hall voltage output terminal are arranged. It may be said that there is a magnetic sensing portion in the depletion layer suppression region, and a control current input terminal and a Hall voltage output terminal are disposed therein.

  Furthermore, it is preferable not to arrange a P-well region or a P-type diffusion region that separates the Hall element from other elements near the Hall element. When the P-type impurity concentration region and the N-type impurity region Hall magnetic sensing portion are joined, the depletion layer greatly extends to the Hall magnetic sensing portion having a relatively low impurity concentration, thereby suppressing the flow of control current. It is because it ends. At least 5 μm or more is required to separate the P-well region and the P-type diffusion region from the Hall magnetic sensing portion.

  By maintaining the above relationship, the control current flows between the control current terminals of the magnetic sensing part having a high N-type impurity concentration, so that the depletion generated at the junction between the depletion layer suppression region and the P-type substrate region in the periphery thereof. The control current can be passed through the Hall magnetic sensor without being affected by the layer. Therefore, when the Hall voltage output terminals are 11, 13 and the control current input terminals are 12, 14, the resistance value between the terminals and the Hall voltage output terminals are 12, 14, and the control current input terminals are 11, 13. The resistance value between the terminals is constant. Thereby, the offset voltage can be erased by the spinning current.

Moreover, the manufacturing method of the Hall element of the present invention is also easy. First, a first N-type impurity region 122 serving as a depletion layer suppressing layer is formed in the P-type substrate 100. At this time, the concentration of the first N-type impurity region 122 is between 8 × 10 ¹⁴ (atoms / cm ³ ) and 3 × 10 ¹⁵ (atoms / cm ³ ). This can be formed by a normal ion implantation apparatus, but the same effect can be obtained with an N well. Since the first N-type impurity region 122 is used as a depletion layer suppression region if the impurity concentration is sufficiently lower than that of the magnetic sensing portion, the sensitivity and other characteristics of the Hall element are not affected even if the manufacturing variation of the N well is large. . Therefore, it can be formed in common with an N well for providing other elements.

Next, a second N-type impurity region 121 which is a Hall magnetic sensing part is formed. At this time, the concentration of the first N-type impurity region 122 is between 1 × 10 ¹⁶ (atoms / cm ³ ) and 5 × 10 ¹⁶ (atoms / cm ³ ). The impurity region of this concentration can be formed by a normal ion implantation apparatus, and variation in concentration and depth can be made smaller than that of the N well. By forming the Hall element sensing part by ion implantation, it is possible to form a Hall element with small variations in sensitivity.

  Finally, high-concentration impurity regions serving as a control current input terminal and a Hall voltage output terminal are formed. The high-concentration impurity region has a depth of 300 nm, and can be formed in common without requiring a separate process from other elements.

  Further, as an example, a square magnetic sensing portion, a depletion layer suppression region, and a Hall element shape having a control current input terminal and a Hall voltage output terminal at each vertex thereof are taken as an example, but the shape is not limited thereto. A magnetic sensing portion of the second N-type impurity region 121 and a depletion layer suppression region of the first N-type impurity region 122 having a lower impurity concentration than the second N-type impurity region 121 taken wider than the magnetic sensing portion; Any symmetrical Hall element having a control current input terminal and a Hall voltage output terminal of an N-type high-concentration impurity region at each apex and capable of erasing an offset voltage due to spinning current may be used. For example, the cross-shaped Hall element magnetic sensing part tilted by 45 ° as shown in FIG. 6, the hole current control electrode and the Hall voltage output terminal of the N-type high concentration impurity region are suppressed in a depletion layer having a lower impurity concentration than the Hall magnetic sensing part. The same effect can be obtained even in shapes other than the square shape such as the shape arranged in the region.

  As described above, by taking the structure as shown in FIG. 1, it is not necessary to take a complicated circuit or a complicated structure, it is not necessary to add a special process, the influence of the depletion layer on the control current is suppressed, and the spinning current is used. An offset voltage can be erased, a chip size is small, and an inexpensive Hall sensor can be realized.

10, 120 Hall element 100 P-type substrate 110 N-type high concentration impurity region 121 Second N-type impurity region 122 First N-type impurity region 11, 12, 13, 14 Hall voltage output terminal and control current input terminal 2, 12 power supply 3, 13 voltmeter 11 switching signal generator S1, S2, S3, S4 sensor terminal switching means T1, T2, T3, T4 terminals R1, R2, R3, R4 resistance

Claims (5)

The magnetic susceptor is more controlled so that the control current flowing in the Hall element flows away from the junction formed by the magnetic susceptor that is an N-type impurity region and the peripheral part of the magnetic susceptor that is a P-type substrate. Side and bottom surfaces are covered with a depletion layer suppression region which is an N-type impurity region with a low impurity concentration,
A hall sensor, wherein a control current input terminal and a hall voltage output terminal are arranged in the magnetic sensing part.   2. The Hall sensor according to claim 1, wherein the magnetic sensing portion is square or cross-shaped, and has a control current input terminal and a Hall voltage output terminal of an N-type high concentration impurity region at each apex and end thereof.   The hall sensor according to claim 1, wherein the depletion layer suppression region is 3 to 10 μm larger than the magnetic sensing portion. 2. The Hall sensor according to claim 1, wherein a P well region and a P type diffusion region are separated from the magnetic sensing portion by 5 μm or more.   The Hall sensor according to claim 1, wherein the offset voltage can be removed by a spinning current.

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