Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Magnetic field
Reexamination Certificate
2000-06-01
2002-05-28
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Magnetic field
C257S421000
Reexamination Certificate
active
06396114
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Background of the Invention
The present invention relates to a magneto-electric device for use in a magnetic sensor for detecting the number of revolutions of a gear or the like and a manufacturing method therefore.
2. Related Art
In recent years, intelligent household electrical products, industrial machines and automobiles have appeared, causing improvement in a variety of sensor techniques to be required. A hall device which is one of magnetic sensors, is able to output a voltage signal corresponding to the magnetic field. Since the hall device, which is a non-contact type device, is highly resistant against contamination. The hall devices have widely been used. For example, a magnetic sensor incorporating the hall device is employed in a vehicle, such as an automobile, to serve as a rotation sensor for detecting the number of rotation of a gear or the like.
In the foregoing case, the hall device is disposed between a gear (which must be detected) having projections and depressions, and a bias magnet. Thus, an external magnetic field from the bias magnet penetrates the hall device and moves to the surface of the gear having the projections and depressions. Hence it follows that the hall device produces an output of a voltage signal corresponding to the magnitude of the external magnetic field.
When the gear having the projections and depressions has been rotated, the magnetic field is changed due to the projections and depressions of the gear. It leads to a fact that also the magnetic field which penetrates the hall device is changed. The change in the magnetic field causes the voltage signal extracted from the hall device being changed. As a result, the number of revolutions of the groove can be detected in accordance with the change in the voltage signal.
When the sensitivity of the hall device is unsatisfactorily low, a proper output of the detected voltage cannot be obtained. To improve the sensitivity of the hall device in a weak magnetic field, a hall device provided with a magnetic collector has been suggested. FIG.
10
(
a
) is a schematic view showing the hall device provided with a magnetic collector. FIG.
10
(
b
) is a side view. As can be understood from FIGS.
10
(
a
) and
10
(
b
), a hall device body
101
formed by a compound semiconductor is formed on a sub-slate formed by NiZn ferrite. Moreover, input/output terminals
107
,
108
,
109
and
110
are connected to four lead frames
105
.
A top jacket
111
constituted by a magnetic collector in the form of a square magnetic member or a cylindrical magnetic member is disposed on the upper surface of the hall device body
101
. The top jacket
111
, the sub-slate
103
and the lead frames are secured by adhesive agent
113
. The top jacket ll converges an external magnetic field to the hall device body
101
so that the sensitivity of the hall device in a weak magnetic field is improved.
In JP Hei.7-198433A, an area flow meter has been disclosed which incorporates a magnetic sensor provided with the magnetic collector. The magnetic sensor provided with the magnetic collector is shown in FIGS.
11
(
a
) and
11
(
b
). A magnetic collector
127
made of such as permalloy exhibiting excellent permeability formed into a tapered shape is provided for each sensitive surface of the hall device A which is the magnetic sensor. Thus, the magnetic field generated by a magnet is captured by the magnetic collector
127
. The captured magnetic field is converged to a base portion of the magnetic collector
127
, the base portion having a small diameter. Thus, sensitivity is improved. As a result, the magnetic field is converged to the sensitive surface of the hall device, causing the output of the hall device to be enlarged.
In JP.Sho.59-154085A, a magneto-resistance effect device has been disclosed. The disclosed magneto-resistance effect device incorporates a magnetic collection pattern constituted by a thin ferromagnetic film having, high permeability. The magnetic collection pattern is disposed adjacent to a sensor pattern which is used to detect change in the electric resistance, the magnetic collection pattern being disposed while electric insulation being Maintained through a thin insulating film.
The magneto-resistance effect device disclosed in JP.Sho.59-154085A is effective when it is employed as a ferromagnetic magneto-resistance effect device. The ferromagnetic magneto-resistance effect device includes magnetic members disposed such that the sensor surface has sensitivity in the horizontal direction. On the other hand, a satisfactory effect cannot be obtained from a structure, such as a hall device, in which the surface of the device has sensitivity in the vertical direction.
Each of the hall devices shown in
FIGS. 10 and 11
requires an afterward process for bonding the magnetic members to the hall device. It leads to a fact that the overall thickness of the sensor is undesirably enlarged. Moreover, a complicated operation must be performed when each of the magnetic members must be joined to the hall device. As the size of the hall device is reduced, the operation for bonding the magnetic members becomes difficult. Therefore, productivity of the hall devices has been unsatisfactorily low.
Accordingly, the applicant of the invention has applied a magneto-electric device and a manufacturing method therefor in Japanese Patent Publication No. Hei.11-261131 to solve the above-mentioned problems.
As shown in
FIG. 12
, the magneto-electric device includes: a silicon substrate
211
; and a hall device portion
215
formed adjacent to the surface
213
of the silicon substrate
211
and capable of outputting an electric signal corresponding to the magnitude of the external magnetic field. Moreover, the magneto-electric device incorporates an etched groove
219
which is formed on the reverse side
217
of the silicon substrate
211
at a position opposite to the hall device portion
215
. The etched groove
219
is formed into a tapered shape, the diameter of which is gradually reduced as the distance from the reverse side
217
to the hall device portion
215
is shortened. In addition, the magneto-electric device includes a magnetic film
223
formed on the surface of the etched groove
219
and exhibiting a high permeability so as to converge the external magnetic field to the hall device portion
215
.
The magneto-electric device having the above-mentioned structure causes the external magnetic field to be converged to the hall device portion
215
due to the magnetic film
223
formed on the surface of the tapered groove. Since the structure is arranged such that the vertical magnetic field is converged to both of the right side and the reverse side of the hall device portion
215
, it permits the sensitivity of the hall device to be improved even in a weak magnetic field.
The hall device portion
215
is formed in the silicon substrate
211
. Moreover, the magnetic film
223
is formed in the etched groove
219
. Thus, excessive enlargement of the thickness from that of original silicon substrate
211
can be prevented. Hence it follows that the size of the device can be reduced. Since a multiplicity of devices and the magnetic film, which must be formed, can be formed on the silicon substrate, the productivity of the hall device can be improved.
Recently, there is a requirement for the conventional magneto-electric device portion of the foregoing type to improve the effect of converging the magnetic field and the sensitivity of the magneto-electric device in a weak magnetic field.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a magneto-electric device which is capable of furthermore improving the sensitivity in a weak magnetic field by improving the effect of converging a magnetic field to the magneto-electric device portion and a manufacturing method therefor.
To achieve the above-mentioned problems, the present invention is provided with a magneto-electric device including:
a first semiconductor wafer including a first surface and a seco
Le Bau T
Nelms David
Sughrue & Mion, PLLC
Yazaki -Corporation
LandOfFree
Magneto-electric device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Magneto-electric device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magneto-electric device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2840050