Magnetic impedance device, sensor apparatus using the same and method for manufacturing the same

Abstract

A magnetic sensor apparatus includes a semiconductor substrate and a magnetic impedance device for detecting a magnetic field. The magnetic impedance device is disposed on the substrate. The magnetic sensor apparatus has minimum size and is made with low manufacturing cost. Here, the magnetic impedance device detects a magnetic field in such a manner that impedance of the device is changed in accordance with the magnetic filed when an alternating current is applied to the device and the impedance is measured by an external electric circuit.

1 - 33 . (canceled)  
   
   
       34 . A rotation sensor apparatus comprising: 
 a rotation body for providing a periodic change of intensity of magnetic field disposed around the rotation body in accordance with rotation of the rotation body;    a magnetic sensor having a magnetic impedance device for detecting the periodic change of the intensity of magnetic field so as to detect the rotation of the rotation body; and    a separation shield for separating between the rotation body and the magnetic sensor,    wherein the magnetic sensor detects the rotation of the rotation body through the separation shield.    
   
   
       35 . The apparatus according to  claim 34 , 
 wherein the separation shield is a casing for covering the rotation body, and    wherein the magnetic sensor detects the rotation of the rotation body disposed in the casing.    
   
   
       36 . The apparatus according to  claim 34 , 
 wherein the rotation body is made of a magnetic material or a material including the magnetic material, and has a gearwheel shape.    
   
   
       37 . The apparatus according to  claim 36 , further comprising: 
 another magnetic sensor,    wherein two magnetic sensors are arranged in parallel so as to separately by a half of pitch of the rotation body and symmetrically disposed around a rotation axis of the rotation body, and    wherein two magnetic sensors output signals, respectively, so that a differential output signal is obtained.    
   
   
       38 . The apparatus according to  claim 36 , 
 wherein the rotation body is a gear connecting to a crankshaft of an engine of a vehicle, and    wherein the separation shield is an engine block of the vehicle.    
   
   
       39 . The apparatus according to  claim 36 , 
 wherein the rotation body is a cam connecting to a camshaft of an engine of a vehicle, and    wherein the separation shield is an engine block of the vehicle.    
   
   
       40 . The apparatus according to  claim 34 , 
 wherein the rotation body is a cylindrical magnet having a pair of N and S poles, which is alternately disposed on circumferential periphery of the cylindrical magnet.    
   
   
       41 . The apparatus to  claim 40 , further comprising: 
 another magnetic sensor,    wherein two magnetic sensors are arranged in parallel so as to separate by a half of pitch of the rotation body and symmetrically disposed around a rotation axis of the rotation body, and    wherein two magnetic sensors output signals, respectively, so that a differential output signal is obtained.    
   
   
       42 . The apparatus according to  claim 40 , 
 wherein the rotation body is a magnetized rotor mounted on a rotation shaft of a wheel of a vehicle, and    wherein the separation shield is a wheel hub of the vehicle.    
   
   
       43 . The apparatus according to  claim 34 , 
 wherein the separation shield is made of non-magnetic material.    
   
   
       44 . The apparatus according to  claim 34 , 
 wherein the separation shield is a sensor casing for covering the magnetic sensor,    wherein the sensor casing is made of magnetic material and includes an opening, which faces the rotation body, and    wherein the magnetic sensor detects the rotation of the rotation body through the opening of the sensor casing.    
   
   
       45 . The apparatus according to  claim 44 , 
 wherein the sensor casing is made of a permanent magnet.    
   
   
       46 . The apparatus according to  claim 45 , 
 wherein the sensor casing has both ends thereof, which open for an outside of the sensor casing,    wherein the sensor casing has a sidewall for providing the permanent magnet, and    wherein the magnet sensor is disposed in the sensor casing.    
   
   
       47 . The apparatus according to  claim 44 , 
 wherein the rotation body is made of magnetic material or a material including the magnetic material, and has a gearwheel shape.    
   
   
       48 . The apparatus according to  claim 47 , 
 wherein the rotation body is a gear connecting to a crankshaft of an engine of a vehicle.    
   
   
       49 . The apparatus according to  claim 44 , 
 wherein the rotation body is a cam connecting to a camshaft of an engine of a vehicle, and    wherein the cam is made of a magnetic material or a material including the magnetic material.    
   
   
       50 . The apparatus according to  claim 44 , 
 wherein the rotation body is a cylindrical magnet having a pair of N and S poles, which is alternately disposed on a circumferential periphery of the cylindrical magnet.    
   
   
       51 . The apparatus according to  claim 44 , 
 wherein the rotation body is a magnetized rotor mounted on a rotation shaft of a wheel of a vehicle.    
   
   
       52 . The apparatus according to  claim 34 , 
 wherein the magnetic impedance device detects a magnetic field in such a manner that impedance of the device is changed in accordance with the magnetic field when an alternating current is applied to the device and the impedance is measured by an external electric circuit,    wherein the magnetic impedance device includes a magnetic layer made of Ni—Fe series alloy film,    wherein the magnetic layer has a length defined as L 1  in an energization direction of the alternating current, a width defined as L 2  in a perpendicular direction perpendicular to the energization direction, and a thickness of the magnetic layer define as L 3 ,    wherein the ratio of the length and the width and the thickness is defined as α, i.e., α=L 11 /L 2 , and the ratio of the width and the thickness is defined as β, i.e., β=L 2 /L 3 ,    wherein the ratio α is equal to or larger than 10, and the ratio β is in a range between 1 and 50, and    wherein the width L 3  is equal to or larger than 5 μm.    
   
   
       53 . The apparatus according to  claim 34 , 
 wherein the magnetic impedance device detects a magnetic field in such a manner that impedance of the device is changed in accordance with the magnetic field when an alternating current is applied to the device and the impedance is measured by an external electric circuit,    wherein the magnetic impedance device includes a magnetic layer made of Ni—Fe series alloy film,    wherein the magnetic layer has a length defined as L 1  in an energization direction of the alternating current, a width defined as L 2  in a perpendicular direction perpendicular to the energization direction, and a thickness of the magnetic layer defined as L 3 , and    wherein the length L 1  is equal to or larger than 100 μm, the thickness L 3  is equal to or larger than 0.3 μm.    
   
   
       54 . The apparatus according to  claim 53 , 
 wherein the Ni—Fe series alloy film has a composition such that a content of Ni in the Ni—Fe series alloy film is in a range between 65 wt % and 90 wt %, and/or a content of Fe in the Ni—Fe series alloy film is in a range between 10 wt % and 35 wt %,    wherein the Ni—Fe series alloy film has a plurality of grains, dimensions of which are equal to or smaller than 100 nm, and    wherein the substrate has a surface roughness, which is equal to or smaller than 1300 nm.