1. Field of the Invention
The present invention relates to a magnetic detector for detecting an external magnetic field using a magnetoresistance effect element layer or the like. More specifically, the present invention relates to a magnetic detector that enables highly accurate magnetic detection by adjusting an electrical resistance value, and a method for manufacturing the magnetic detector.
2. Description of the Related Art
A magnetic detector is known. In this magnetic detector, a magnetoresistance effect element layer having an electrical resistance which changes in response to an external magnetic field is connected in series to a resistance element layer having an electrical resistance which does not change in response to an external magnetic field, a power supply voltage is applied to the magnetoresistance effect element layer and the resistance element layer, and a potential at a midpoint between the magnetoresistance effect element layer and the resistance element layer is detected, whereby an external magnetic field is detected. A magnetoresistance effect element layer having an electrical resistance which changes in response to an external magnetic field may be used as the foregoing resistance element layer.
In this type of magnetic detector, the electrical resistances of the magnetoresistance effect element layer and the resistance element layer are adjusted so that the potential at the midpoint is half the power supply voltage when there is no external magnetic field. When an external magnetic field is generated, the electrical resistance of the magnetoresistance effect element layer changes, and thereby the potential at the midpoint changes. In this way, an external magnetic field is detected by measuring a change in potential at the midpoint.
Methods for adjusting the electrical resistances of the magnetoresistance effect element layer and the resistance element layer are disclosed in Japanese Unexamined Patent Application Publications No. 2008-46076 and No. 2008-58183.
In the method for adjusting electrical resistance disclosed in Japanese Unexamined Patent Application Publication No. 2008-46076, as illustrated in FIG. 21, a plurality of current bypasses, i.e., a first current bypass 601, a second current bypass 602, and a third current bypass 603, are provided to a resistance element layer 703 having an electrical resistance which does not change in response to an external magnetic field, in a stepwise form along the longitudinal direction of the element (X2-X1 direction).
Also, a protruding region 604 that protrudes in a direction away from the resistance element layer 703 is provided in each current bypass.
When a difference in resistance value between a magnetoresistance effect element layer 701 having an electrical resistance which changes in response to an external magnetic field and the resistance element layer 703 is outside an allowable range, current paths in the protruding regions 604 are cut off in order from the protruding region 604 that protrudes the most viewed from the resistance element layer 703, and thereby the difference in resistance value is adjusted to be within the allowable range.
In this method, a plurality of protruding current bypasses are provided to the resistance element layer 703, which inhibits a reduction of the size of a magnetic detector.
In the method for adjusting electrical resistance disclosed in Japanese Unexamined Patent Application Publication No. 2008-58183, as illustrated in FIG. 22, magnetoresistance effect element layers 701 and 702 having an electrical resistance which changes in response to an external magnetic field and resistance element layers 703 and 704 having an electrical resistance which does not change in response to an external magnetic field are connected in series, respectively. Also, there are provided output conductive layers 705 and 706 that are connected to midpoints between the magnetoresistance effect element layers 701 and 702 and the resistance element layers 703 and 704, respectively, and that output potentials of the midpoints.
Each of the output conductive layers 705 and 706 extends in one longitudinal direction of the magnetoresistance effect element layers 701 and 702 and the resistance element layers 703 and 704. Each of the output conductor layers 705 and 706 is electrically connected to one of the magnetoresistance effect element layers 701 and 702 and the resistance element layers 703 and 704 via a conductive connection layer 707 or 708. In this way, the positions of the connection layers 707 and 708 are changed, so that the electrical resistance value of one of the magnetoresistance effect element layers 701 and 702 and the resistance element layers 703 and 704 is adjusted.
In the adjustment of changing the positions of the connection layers 707 and 708, a step-and-repeat exposure system (stepper), which performs exposure using a reticle by moving a substrate using a step-and-repeat method, is typically used for forming the pattern of the connection layers 707 and 708. Thus, the pattern of the connection layers 707 and 708 is formed through a plurality of exposure operations. In the plurality of exposure operations, variations in dimension and variations in alignment of the connection layers 707 and 708 occur. Accordingly, highly accurate adjustment of electrical resistance cannot be performed.