The present invention relates to sensor technology field, and more particularly, to a magnetic sensor with shunting layers and a manufacturing method thereof.
Sensor is a physical device, which could detect and sense the external signal and the physical conditions (such as light, heat, humidity) and/or chemical composition (such as smoke), and will transfer the information into electrical signal for transmitting to other devices. Magnetic sensor is one kind of the sensor. The magnetic sensor serves the function of changing the magnetic performance of the sensitive element induced by magnetic field, current, stress-strain, temperature and light change, etc into electrical signal, so as to measure the related physical quantity, especially the tiny physical quantity of the device. Since the magnetic sensor is characteristic by its high sensitivity in comparison to other type of sensors, it is widely used in the field of aerospace, geological exploration, medical imaging, and information acquisition and so on. As the progress of technology and the magnetic sensor is advantage with its low power consumption, small volume, high sensitivity, easy integrated, low cost, fast response, high resolution, high stability, high reliability, the magnetic sensor is a core portion of the magnetic sensor device.
In certain magnetic sensing applications, there is a need to use long stripes of magnetic sensor element to match the spatially distributed magnetic signals. Long stripe is also essential to achieve large sensor resistance and low power consumption. Long magnetic stripes tend to have larger magnetic coercive force due to the difference in the demagnetization factors between the long axis and short axis directions, and bring serious magnetic hysteresis. Large coercive force will cause low Signal-to-Noise and even low sensitivity. To overcome the large coercive force, additional magnetic layers, such as shields, hard magnetic bias, or current bias layers are commonly employed. However, either the shield or bias layers will cause a reduction in sensor sensitivity, in addition to the process complexity and extra cost incurred.
Therefore, an improved alternative is to align multiple isolated magnetic sensor elements in series.
Accordingly, a need has arisen for providing an improved magnetic sensor with shunting layers to reduce the coercive force thereof, and a manufacturing method for the magnetic sensor, to overcome the above-mentioned drawbacks.
One objective of the present invention is to provide a magnetic sensor, with a plurality of shunting layers forming on a magnetic sensor bar. Owing to any part of the magnetic sensor bar which is laminated with the shunting layers becomes inactive, and the magnetic sensor bar has an integral structure, magnetic sensor has low coercive force and high sensitivity performance, and high antistatic ability and better reliability thereof are obtained.
Another objective of the present invention is to provide a manufacturing method of magnetic sensor, with the magnetic sensor having a plurality of shunting layers forming on a magnetic sensor bar. Owing to any part of the magnetic sensor bar which is laminated with the shunting layers becomes inactive, and the magnetic sensor bar has an integral structure, magnetic sensor has low coercive force and high sensitivity performance, and high antistatic ability and better reliability thereof are obtained.
To achieve the above-mentioned objects, the present invention provides a magnetic sensor with shunting layers, and the magnetic sensor includes a magnetic sensor bar which has an integral structure; and a plurality of shunting layers whose resistivity is lower than the magnetic sensor bar, respectively forming on the magnetic sensor bar in length direction without any physical separation therebetween, with spaces between every two adjacent shunting layers; and two electrode pads respectively forming on two ends of the magnetic sensor bar.
As an embodiment of the present invention, the ratio of the width of magnetic sensor bar to the space between any two adjacent shunting layers is within the range of 0.8-1.2.
Preferably, the width of magnetic sensor bar is identical to the space between any two adjacent shunting layers. As such, low coercive force could be obtained to achieve high sensitivity performance of the magnetic sensor.
As an embodiment of the present invention, the shunting layer is a ring enclosing the magnetic sensor bar perpendicular to its length direction.
As another embodiment of the present invention, the shunting layer has a shape of square, rectangular or oval to laminate on the magnetic sensor bar.
As another embodiment of the present invention, the material of the shunting layer is composed of gold, copper, silver, or other low resistivity metals.
As yet another embodiment of the present invention, the magnetic sensor bar is Anisotropic Magneto Resistance, Giant Magneto Resistance or Tunneling Magneto Resistance.
As yet another embodiment of the present invention, the magnetic sensor further comprises a plurality of seedlayers correspondingly sandwiched between the shunting layers and the magnetic sensor bar, so as to achieve good adhesion therebetween.
Preferably, the seedlayer is composed of chromium, titanium or tantalum.
As still another embodiment of the present invention, the magnetic sensor further comprises an undercoat layer composed of insulating material on which the magnetic sensor bar formed, and a substrate with the undercoat layer formed thereon.
Preferably, the undercoat layer is consisted of alumina or silicon oxide, and the substrate is consisted of silicon, magnesium oxide, sapphire, AlTiC or glass.
As still another embodiment of the present invention, the magnetic sensor is covered with a protection layer, which is composed of alumina, silicon oxide, ink or polyimide.
To achieve the above-mentioned objects, the present invention also provides a manufacturing method of magnetic sensor, which includes the following steps: providing a substrate; depositing a undercoat film on the substrate, depositing a magnetic sensor film on the undercoat or directly on substrate which already has an insulating surface layer, and etching the magnetic sensor film into a plurality of magnetic sensor bars, each of which has an integral structure; depositing a shunting film without any physical separation therebetween on the magnetic sensor bar, and patterning the shunting film into a plurality of shunting layers, whose resistivity is lower than the magnetic sensor bar, formed in length direction of the magnetic sensor, with spaces between every two adjacent shunting layers; and depositing two electrode pads respectively on two ends of the magnetic sensor bar.
As an embodiment of the present invention, the ratio of the width of magnetic sensor bar to the space between any two adjacent shunting layers is within the range of 0.8-1.2.
Preferably, the width of magnetic sensor bar is identical to the space between any two adjacent shunting layers. As such, low coercive force could be obtained to achieve high sensitivity performance of the magnetic sensor.
As an embodiment of the present invention, patterning of the magnetic sensor film is carried out by dry or wet etching with photo mask.
As an embodiment of the present invention, patterning of the shunting film is carried out by directly depositing into photo patterns or after deposition the dry or wet etching.
As another embodiment of the present invention, the shunting layer is a ring enclosing the magnetic sensor bar perpendicular to its length direction.
As another embodiment of the present invention, the shunting layer has a shape of square, rectangular or oval to laminate on the magnetic sensor bar.
As yet another embodiment of the present invention, the material of the shunting layer is composed of gold, copper, silver, or other low resistivity metals.
As yet another embodiment of the present invention, the magnetic sensor bar is Anisotropic Magneto Resistance, Giant Magneto Resistance, or Tunneling Magneto Resistance.
As still another embodiment of the present invention, the magnetic sensor further comprises a plurality of seedlayers correspondingly sandwiched between the shunting layers and the magnetic sensor bar, so as to achieve good adhesion therebetween.
Preferably, the seedlayer is composed of chromium, titanium or tantalum.
As still another embodiment of the present invention, the undercoat layer is consisted of alumina or silicon oxide, and the substrate is consisted of silicon, magnesium oxide, sapphire, AlTiC or glass.
As still another embodiment of the present invention, the manufacturing method further comprises a step of depositing an undercoat layer composed of insulating material on the substrate, with the magnetic sensor film laminated thereon.
As still another embodiment of the present invention, the manufacturing method further comprises a step of covering the magnetic sensor with a protection layer, which is composed of alumina, silicon oxide, ink or polyimide.
To achieve the above-mentioned objects, the present invention also provides manufacturing method of magnetic sensor, and the method comprises the following steps: providing a substrate; depositing a magnetic sensor film on the substrate, and etching the magnetic sensor film into a plurality of magnetic sensor bars, each of which has an integral structure; arranging a photo mask directly on the magnetic sensor bar with a plurality of specific areas of the photo mask exposing the magnetic sensor bar, then depositing a shunting film onto and cover the whole the photo mask, whereby a plurality of shunting layers are formed on the magnetic sensor bar without any physical separation therebetween via said specific areas of the photo mask, and patterning the shunting film into a plurality of shunting layers, whose resistivity is lower than the magnetic sensor bar, formed in length direction of the magnetic sensor, with spaces between every two adjacent shunting layers; and depositing two electrode pads respectively on two ends of the magnetic sensor bar.
In comparison with the prior art, the magnetic sensor has a magnetic sensor bar has an integral structure, and a plurality of shunting layers forming on a magnetic sensor bar. Owing to any part of the magnetic sensor bar which is laminated with the shunting layers becomes inactive, and the magnetic sensor bar has an integral structure, magnetic sensor have low coercive force and high sensitivity performance, and high antistatic ability and better reliability thereof are obtained.
Other aspects, features, and advantages of this invention will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of this invention.
The accompanying drawings facilitate an understanding of the various embodiments of this invention. In such drawings:
Various preferred embodiments of the invention will now be described with reference to the figures, wherein like reference numerals designate similar parts throughout the various views. According to the present invention, the magnetic sensor is used to sense the spatially distributed magnetic signals.
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Furthermore, since the magnetic sensor bar according to the embodiments of the present invention is separated into multiple isolated elements in magnetic level via the shunting layers, without any physical breaking and removal therefore, hence, the magnetic sensor bar has an integral structure. No physical separation is occurred in the longitudinal direction of the magnetic sensor and much better integrity of the anti-ferromagnetic layer is obtained, consequently, no changes in magnetic shape and stress anisotropy are occurred to the magnetic sensor, so that high antistatic ability and better reliability of the magnetic sensor are obtained. Moreover, no changes in magnetic shape and stress anisotropy is occurred, thus, small coercive force and high sensitivity of the magnetic sensor is achieved.
The present invention is also provided with a method for manufacturing the magnetic sensor according to the above-mentioned embodiments.
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It should be note that, in other embodiment of the present invention, the magnetic sensor film could be etched by other dry or wet etching methods such as ion milling, RIE, wet chemical etching, etc; and the shunting film could be etched by other dry or wet etching methods such as ion milling, RIE, wet chemical etching, etc.
Preferably, the above method for manufacturing the magnetic sensor further comprises sandwiching a plurality of seedlayers correspondingly between the shunting layers and the magnetic sensor bar, so as to achieve good adhesion therebetween. And the seedlayer is composed of chromium, titanium or tantalum.
Preferably, the manufacturing method further comprises a step of depositing an undercoat layer composed of insulating material on the substrate, with the magnetic sensor film laminated thereon. And the undercoat layer is consisted of alumina or silicon oxide.
In other embodiment of the present invention, the manufacturing method further comprises a step of covering the magnetic sensor with a protection layer, which is composed of alumina, silicon oxide, ink or polyimide.
Another embodiment of the present invention also provides a manufacturing method of magnetic sensor, and the method comprises the following steps: providing a substrate; depositing a magnetic sensor film on the substrate, and etching the magnetic sensor film into a plurality of magnetic sensor bars, each of which has an integral structure; arranging a photo mask directly on the magnetic sensor bar with a plurality of specific areas of the photo mask exposing the magnetic sensor bar, then depositing a shunting film onto the photo mask and cover the whole the photo mask, whereby after the photo mask is removed, a plurality of shunting layers are formed on the magnetic sensor bar without any physical separation therebetween via said specific areas of the photo mask, and patterning the shunting film into a plurality of shunting layers, whose resistivity is lower than the magnetic sensor bar, formed in length direction of the magnetic sensor, with spaces between every two adjacent shunting layers; and depositing two electrode pads respectively on two ends of the magnetic sensor bar.
While the invention has been described in connection with what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.