JPH01251763A - Vertical hall element and integrated magnetic sensor - Google Patents

Abstract

PURPOSE:To measure a magnetic field which is parallel to the face of an element and to realize the integration in one chip by installing the following: current output electrodes formed at symmetrical positions via a current input electrode; Hall voltage output electrodes installed near a position perpendicular to a current direction of the current input electrode in order to take out a Hall voltage. CONSTITUTION:An n-type conductive layer whose conductivity is different from that of a surface layer is grown epitaxially on the surface layer of a silicon substrate 1 of a p-type conductivity. In addition, an island-like active region 2 which has been insulated electrically from a peripheral part is formed. An n<+> buried layer 3 which has been doped excessively with an impurity and whose pattern has a width W is formed in a position of a depth L at the bottom of the region; a current input electrode 4 is formed on this upper-part surface; current output electrodes 5 used to take out an electric current are arranged and installed in symmetrical positions via the electrode. When a vertical type Hall element is formed in this manner, it is possible to measure a magnetic field B in a direction (x) of a face parallel to the element.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a vertical Hall element and an integrated magnetic sensor in which the vertical Hall element and a signal processing circuit are integrated. More specifically, the present invention relates to a new smart magnetic sensor that can be formed by a bipolar process and that can realize three-dimensional measurement of a magnetic field with a single chip.

(Background Art) Hall elements formed by a bipolar process have been known. For example, as shown in Figure 9,
On the surface of a silicon substrate (a) with p-type conductivity,
An epitaxial layer (a) with type conductivity is formed, and on its surface there is a current input electrode (2), a current output type, and #! (1) is provided, and a Hall voltage output electrode (O) is further provided in a direction perpendicular to the direction of current.

However, this conventional Hall element has a fundamental problem in that it can only measure magnetic fields in a direction perpendicular to the element surface. In other words, it was limited to horizontal Hall elements.

In other words, the Hall effect means that in the current direction (X) and magnetic field direction (2), current carriers are bent in the y direction on the xy plane by the magnetic field, and this creates a potential difference in the y direction. In the above-mentioned previously known Hall element structure, only the magnetic field perpendicular to the element surface generates the Hall voltage.

When performing three-dimensional measurement of magnetic fields using such conventional elements, the elements must be placed perpendicular to the magnetic field, so it is necessary to incorporate at least three horizontal Hall elements three-dimensionally. Met. The structure of a Gaussmeter as a typical example thereof can be shown as shown in FIG.

As shown in this example, three horizontal Hall elements (force) were built into the tip of the probe, and each output was output.

In this way, with conventional Hall elements, it is possible to measure the magnetic field only in the direction perpendicular to the element surface, and it is difficult to measure in the lateral direction.Moreover, it is difficult to measure the magnetic field in the lateral direction. It was essentially impossible to accumulate.

In order to overcome these problems, the inventor of the present invention has been conducting intensive studies to develop a vertical hole that enables magnetic field measurement parallel to the element surface and that can be integrated into a single chip. We have been working hard to realize the device.

As a result, the inventor of the present invention has already discovered the structure of a vertical Hall element based on a new idea, and has further improved this structure so that it can be put to practical use, thereby arriving at the present invention.

(Disclosure of the Invention) This invention was made in light of the above-mentioned circumstances, and uses a normal bipolar process to realize a vertical Hall element that can measure a magnetic field parallel to a plane. It is. Another object of the present invention is to provide a smart magnetic sensor that integrates this element and makes it possible to three-dimensionally measure a magnetic field using a single chip.

To achieve this purpose, the vertical Hall element of the present invention has an active region formed in an island shape by epitaxial growth on the surface layer of the substrate, which has conductivity of opposite polarity to the substrate and is electrically insulated from the surrounding area. There is a buried layer formed at the bottom of this active region that serves as a current bus in the film thickness direction with good conductivity, and a current input electrode formed on the upper surface of the current bus. The formed current output electrode,
It consists of a Hall voltage output electrode provided in the vicinity of the current input electrode at right angles to the current direction to take out the Hall voltage, making it possible to measure magnetic fields parallel to the element surface without being affected by perpendicular magnetic fields.

The vertical Hall element and integrated magnetic sensor of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 illustrates the structure of a vertical Hall element according to the present invention. (a), (b), and (c') are respectively plan views;
An AA' cross-sectional view and a BB' cross-sectional view are shown.

This vertical Hall element is shown in Fig. 1 (a), (b), and (c).
As shown in Figure 2, an n-type conductive layer having a conductivity different from that of the silicon substrate (1) is epitaxially grown on the surface layer of a p-type conductive silicon substrate (1), and a layer of the substrate (1) is grown around a desired region. ) by forming by diffusion a ρ-type conductive layer having the same conductivity as t! ), this active region t! U
At the bottom of (2), an n+ buried layer (3) having a pattern with a width W and excessively doped with impurities is provided at a depth L, and this is used as a current bus.

On the upper surface of the n'' buried layer (3) as a current bus, there is a current input type I (4) for flowing current, and a current output electrode (5) for taking out current to a symmetrical position via this. ) and a current input type ′!f!(4
) is provided with a Hall voltage output electrode (6) for extracting the Hall voltage so as to be perpendicular to the current direction.

In this case, the shape of the Hall voltage output electrode (6) has a depth L
, and this L is made sufficiently small compared to W.

In a vertical Hall element having such a structure, by flowing a current in the thickness direction (z) of the element, it is possible to measure the magnetic field (B) in the direction (x) of a plane parallel to the element. This flow of current in the film thickness direction (z) is made possible by the presence of the n+ buried layer (3) formed using a normal bipolar process.

The current flowing from the current input electrode (4>) flows into the n+ buried layer (3) and flows out from the current output electrode (5). In this state, when a magnetic field B is applied in a direction parallel to the element surface (X>), Carriers are bent in the y direction directly under the current input electrode (4), and a Hall voltage is generated at the pole voltage output electrode (6).

In this structure, the current output electrodes (5) are provided at symmetrical positions and the lateral current is made symmetrical with respect to the Hall voltage output electrode (6), so that the output is not affected by the magnetic field perpendicular to the chip surface. That's what I do.

Assuming that the thickness of the Hall element is t, the Hall voltage output v11 of the vertical Hall element with this structure can be expressed by the following equation when a magnetic field of magnetic flux density B is applied.

(R11 indicates the Hall coefficient) This also indicates the sensitivity of the vertical Hall element.

That is, the sensitivity (S) is It can be expressed as

The vertical Hall element of the present invention is compatible with a normal bipolar IC process, and it is easy to incorporate a peripheral circuit and a sensor section into one chip to form an integrated magnetic sensor.

An example of an integrated magnetic sensor that measures the direction (angle) of a magnetic field will be given below.

FIG. 2 is a conceptual diagram showing an example of this integrated magnetic sensor. Two vertical Hall elements (7) are integrated so that the direction of Hall voltage is perpendicular to each other, and their respective outputs Vx,
, i.e., tan (v, /
Signal processing diagram for calculating vx)! (8) is integrated. Here, vx is the X component of magnetic flux density B, that is, B8=Bc
Similarly, vy is proportional to osθ, and vy is the X component, that is, B y
Proportional to =B s + nθ. This results in the output
. The direction of the magnetic field can be measured from

FIG. 3 shows an example of an integrated magnetic sensor that allows three-dimensional measurement of magnetic fields.

This is an integration of one horizontal Hall element (9) that measures the Z component of the magnetic flux density B and two vertical Hall elements (7) that measure the x and X components.

For example, in this example, each Hall voltage output type II
(10) can be arranged within a circle with a radius of 100 μm.

As an example of a circuit for signal processing to realize these integrated magnetic sensors, the circuit shown in FIG. 4 can be exemplified.

Corresponding to the magnetic sensor in FIG. 3, each Hall voltage V,
V, V are x by the V, /I conversion circuit (11)
y Z B , B , B are converted into currents indicating transformer x y Z linear circuit (12) and current mirror circuit.

FIG. 5 shows a circuit diagram in which a three-dimensional magnetic sensor is actually integrated on the same substrate. A very simple circuit makes it possible to measure the absolute value of three-dimensional magnetic flux density.

Figure 6 shows the measurement method (a) of the three-dimensional integrated magnetic sensor.
and the result (b) is shown.

The direction of the magnetic field is 360° in the x-y plane, 0° in the Z direction, 3
The measurement results when changing the angle to 0°, 60°, and 90° are shown in Figure 6 (b), which makes it possible to measure the absolute value of the three-dimensional magnetic field regardless of the direction of the magnetic field. It is shown that.

Note that the present invention is not limited to the above example, and instead of the vertical Hall element shown in FIG. 1, an integrated magnetic sensor may be constructed using the vertical Hall element shown in FIG. 7. .

The Hall element shown in FIG. 7 has one current output electrode (15) corresponding to the current input electrode (14). This structure also makes it possible to measure the magnetic field in the direction parallel to the chip surface, and by integrating two Hall elements (16) at right angles, a magnetic sensor similar to that shown in Fig. 2 can measure the direction of the magnetic field. It is also easy to configure.

Next, the present invention will be further explained by showing examples.

(Example) The vertical Hall element shown in FIG. 1 was manufactured, and its sensitivity was investigated. FIG. 8 shows the results.

As is clear from Fig. 8, the following formula is satisfied. All Hall elements have good linearity, and the temperature characteristics change in sensitivity by 2 at 5 to 50 degrees Celsius.
It was within %.

Furthermore, when a magnetic field was applied in a fixed direction and the element was rotated within it, the error of the output voltage from the theoretical value was 1.5% at most.

Furthermore, when the width (W) of the n+ buried layer was 14 μm, the sensitivity was 75 V/AT.

Extremely good sensitivity was obtained.

(Effects of the Invention) The present invention provides an integrated magnetic sensor and a vertical Hall element that can detect a magnetic field parallel to the chip surface and can be manufactured by a standard bipolar process.

A smart sensor will be realized by integrating an extremely sensitive Hall element that is unaffected by magnetic fields perpendicular to the chip onto a single chip.

[Brief explanation of the drawing]

FIGS. 1(a), 1(b), and 1(c) are a plan view and a sectional view, respectively, showing an example of the vertical pole element of the present invention. Second
The figure is a perspective view showing an integrated magnetic sensor for magnetic field direction measurement. FIG. 3 is a plan view of an integrated magnetic sensor for three-dimensional measurement of magnetic fields. FIG. 4 is a block diagram showing a signal processing circuit of the integrated magnetic sensor. FIG. 5 is a circuit diagram showing a magnetic sensor and a circuit integrated on the same substrate. FIGS. 6A and 6B are a perspective view and a magnetic field measurement diagram showing the measurement method and results of the three-dimensional integrated magnetic sensor, respectively. FIGS. 7(a) and 7(b) are a plan view and a sectional view showing another vertical pole element used in the present invention. FIG. 8 is a sensitivity curve diagram showing the sensitivity of the vertical Hall element. FIG. 9 is a perspective view of a conventional horizontal Hall element, and FIG. 10 is a perspective view of a conventional Gauss meter. 1... Silicon substrate 2... Active region 3...
n+ buried layer 4... Current input electrode 5... Current output electrode 6... Ball voltage output electrode 7... Vertical Hall element 8... Signal processing circuit 9... Horizontal Hall element 10...・Hall voltage output electrode 11...V/I conversion circuit 12...Translinear circuit 13...Current mirror circuit 14...Current input electrode 15...Current output electrode 16...Hall element agent Patent Attorney Toshio Nishizawa Figure 2 Figure 3 Figure 4 (a) 6 :A (b) Figure 7 (a) (b) Figure 8 (μm) n+ Width of buried layer (W) Figure 9 Figure 10

Claims (5)

[Claims] (1) Forming a layer with conductivity different from that of the substrate by epitaxial growth on the surface of a silicon substrate, and forming a layer with the same conductivity as the substrate in the peripheral area of the required area by diffusion, thereby creating an electrical connection with the peripheral area. An insulated island-shaped active region, a buried layer formed at the bottom of this active region that serves as a highly conductive current bus in the film thickness direction, a current input electrode formed on the upper surface of the current bus, and a current input electrode formed on the top surface of the current bus. It consists of a current output electrode formed at symmetrical positions via the input electrode, and a Hall voltage output electrode provided in the vicinity perpendicular to the current direction of the current input electrode to take out the Hall voltage, and parallel to the element surface. A vertical Hall element that enables magnetic field measurement without being affected by vertical magnetic fields. (2) An integrated magnetic sensor capable of measuring the direction of a magnetic field, in which two of the vertical Hall elements according to claim (1) are disposed in perpendicular directions and integrated including a signal processing circuit. (3) Two vertical Hall elements and one horizontal Hall element according to claim (1) are integrated using a bipolar process, and the magnetic field can be measured in three dimensions when arranged in a desired shape. Integrated magnetic sensor. (4) In the integrated magnetic sensor according to claim (3), by integrating together a signal processing circuit consisting of a V/I conversion circuit, a translinear circuit, and a current mirror circuit for output processing, An integrated magnetic sensor that can measure the absolute value of a magnetic field. (5) The vertical Hall element according to claim (1) has a current input electrode and a current output electrode as a pair, thereby configuring the integrated magnetic sensor according to claim (2). Integrated magnetic sensor.