JPH0122995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a Hall element that uses a transistor to extract Hall voltage.

Figures 1 and 2 show conventional Hall elements, Figure 1 shows a planar structure excluding internal wiring layers made of aluminum etc., and Figure 2 shows a cross section taken along the line - - of the Hall element shown in Figure 1. . In this Hall element, an epitaxial layer 4 is formed on the surface of a P-type semiconductor substrate 2, and this epitaxial layer 4 has a certain level of separation in an isolation region 6 in which P ⁺ type diffusion is formed in a direction perpendicular to the semiconductor substrate 2. Separated into ranges. Diffusion regions 8 and 10 are formed facing each other at the edges of the epitaxial layer 4 separated in the longitudinal direction as conductive regions for supplying hole current. Electrode 1
2 and 14 are formed, respectively.

Hall voltage detection sections 16 and 18 are set to face each other at the edges of the epitaxial layer 4 in the width direction, and P-type diffusion regions 20 and 22 are formed in the Hall voltage detection sections 16 and 18. In the portion facing the surface layer of the epitaxial layer 4 from the diffusion regions 20 and 22, there is a layer having the same conductivity type as the epitaxial layer 4.
The sensor parts 24 and 26 are formed to face each other by emitter diffusion of N ⁺ . This sensor section 24, 26
Electrodes 28 and 30 are formed on the surface portion of. In addition, in FIG. 2, 32 is an oxide film.

In such a Hall element, the sensor parts 24 and 26 for detecting Hall voltage require considerable precision in terms of size, etc. in order to increase detection sensitivity, and if the precision is low, the distribution of Hall current There are disadvantages such as the Hall voltage is disturbed, the Hall voltage is lowered, and sufficient gain cannot be obtained. Therefore, the sensor section 24,
26 needs to be made small so as not to disturb the hole current distribution.

In addition, in the manufacturing process of such a Hall element,
The areas 20 and 22 of the portions where the sensor parts 24 and 26 will be formed are formed by base diffusion, and the sensor parts 24 and 26 are
is formed simultaneously during emitter diffusion. For this reason, an alignment error occurs in each photoresist process of the base and emitter, and the sensor part 2
4 and 26 may become non-uniform. Such an alignment error occurring in the sensor sections 24 and 26 becomes an offset of the Hall output.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a Hall element that enables detection of Hall voltage by installing a junction field effect transistor in a Hall voltage detection section and realizes extraction of Hall voltage with high gain.

That is, the Hall element of the present invention includes an epitaxial layer formed on a surface layer of a semiconductor substrate, and a conductive region that is placed opposite to this epitaxial layer with an arbitrary interval and supplies a Hall current to the epitaxial layer. and a differential junction field effect transistor that is installed on the epitaxial layer of each Hall voltage detection section and configured to detect the Hall voltage, and is set at an arbitrary interval in a direction orthogonal to the opposing direction between the conductive regions. It is equipped with an amplifier.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

3 to 5 show embodiments of the Hall element of the present invention. FIG. 3 shows a planar structure excluding an internal wiring layer made of aluminum or the like, and FIG. 4 shows a structure of the Hall element shown in FIG. 3. Line cross section and connection circuit,
FIG. 5 shows an equivalent circuit of the Hall element shown in FIG. 3. In FIGS. 3 to 5, the same parts as those of the Hall element shown in FIG. 1 are given the same reference numerals.

The Hall voltage detection sections 16 and 18 set at the edges of the epitaxial layer 4 in the width direction include junction field effect transistors (hereinafter referred to as J-FETs) 34 and 36, respectively, in order to detect the Hall voltage. It is formed. That is, the Hall voltage detection section 16 has
A P ⁺ -type source 38 and drain 40 are formed at regular intervals, and a channel gate 42 is formed in the epitaxial layer 4 within the interval between the source 38 and drain 40 . Similarly, a source 44 and a drain 46 are formed in the Hall voltage detection section 18, and a channel gate 48 is also formed within the space between them.
is formed. Each source 38, 44 and drain 40, 46 has an electrode 50, 52, 54, 5
6 are formed respectively. As shown in FIG. 4, the channel gates 42 and 48 face the epitaxial layer 4 of the Hall voltage detection sections 16 and 18, and the Hall voltage detection sections 16 and 18 serve as gate electrodes.

Then, as shown in Figure 4, J-FET34,
The electrodes 54 and 56 of the 36 drains 40 and 46 are connected in common by a wiring conductor, and are also connected to a reference potential point via a resistor 58, respectively. In addition, output terminals 60 and 62 for taking out the Hall voltage are formed on the electrodes 50 and 52 of the sources 38 and 44, and a driving voltage Vcc is applied from a voltage application terminal 68 via resistors 64 and 66 individually. It's becoming like that.

As shown in FIG. 5, the J-FETs 34 and 36 constitute a differential amplifier 70, and the Hall voltage is detected as a differential output from output terminals 60 and 62.

With the above configuration, the electrode 1 is placed in the diffusion regions 8 and 10, which are conductive regions that supply hole current.
When a Hall current is caused to flow through the epitaxial layer 4 and a magnetic field is applied in a direction perpendicular to the current through the epitaxial layer 4, the Hall voltage detection section 1
The channel gates 42 and 48 of each J-FET 34 and 36 of 6 and 18 are controlled by the Hall voltage generated in that part, and the Hall voltage is detected according to the Hall current flowing in the epitaxial layer 4 and the orthogonal magnetic field. . This Hall voltage is J-FET34,
The signal is differentially amplified by a differential amplifier 70 composed of 36, and can be taken out from output terminals 60 and 62 at a high gain.

According to this configuration, since it includes an amplifier, it is possible to form a Hall element with high efficiency and a small area, and there is no need to form a point contact as in the conventional case, which reduces manufacturing costs. There is no need to pay attention to accuracy. In addition, unlike the conventional sensor unit installation, since the Hall voltage is applied to the channel gates 42 and 48 of the J-FETs 34 and 36, the impedance becomes high and the distribution of Hall current is not disturbed. Therefore, Hall voltage can be detected with high sensitivity and high gain.

As explained above, according to the present invention, a junction field effect transistor is installed in each Hall voltage detection section of an epitaxial layer constituting a Hall element, and a differential amplifier is configured with each junction field effect transistor. As a result, the Hall voltage detected by each junction field effect transistor can be differentially amplified, and the Hall voltage can be extracted with high sensitivity and high gain without disturbing the Hall current flowing through the epitaxial layer. .

[Brief explanation of drawings]

Figure 1 is a plan view showing a conventional Hall element, Figure 2 is a plan view showing a conventional Hall element.
3 is a plan view showing an embodiment of the Hall element of the present invention, and FIG. 4 is a cross-sectional view of the Hall element shown in FIG. FIG. 5 is a diagram showing a connection circuit, and FIG. 5 is a circuit diagram showing an equivalent circuit of the Hall element shown in FIG. 3. 2... Semiconductor substrate, 4... Epitaxial layer,
8, 10... Diffusion region (conductive region) 16, 18...
... Hall voltage detection section, 34, 36 ... Junction field effect transistor, 70 ... Differential amplifier.

Claims (1)

[Scope of Claims] 1. an epitaxial layer formed on a surface layer of a semiconductor substrate; a conductive region disposed opposite to this epitaxial layer at an arbitrary interval and supplying a hole current to the epitaxial layer; a differential amplifier consisting of each junction field effect transistor installed in the epitaxial layer of each Hall voltage detection section set at an arbitrary interval in a direction perpendicular to the opposing direction between each conductive region to detect a Hall voltage; A Hall element characterized by comprising: