1. Field of the Invention
The present invention relates to a three-dimensional (3D) magnetic sensor chip, especially to a sensor chip which can measure the magnetic flux magnitude in 3D on a plane using a magnetic flux bending concentrating structure.
2. The Prior Arts
Magnetic sensors have been widely used in various fields, and are mainly used to detect magnetic fields. For example, magnetic sensors are used in the magnetic sensors of the earth, linear sensors, and angular sensors and switch sensors to detect the magnetic field so as to perform direction positioning, navigation or measurement. As the technology advances, such as the vehicle navigation systems and smart phones, the need of magnetic sensors in the navigation field has also grown. With the characteristics of magnetic sensing, magnetic sensors can be quickly applied in the navigation and global positioning system. It is the trend of modern electronic design to combine devices with different function into a single electronic product, thus, as the size of the product grows smaller, the design of the magnetic sensors is also challenged.
A conventional magnetic sensor unit includes three magnetic sensing devices of the same structure, where the two magnetic sensing devices are disposed in the vertical direction of a plane to measure the magnitude of the magnetic flux in the X and Y axes. The other magnetic sensing device, which is used to measure the Z axis magnitude of the magnetic flux, is disposed vertically to the other two magnetic sensing devices. As the design of the integrated circuits grows smaller, the vertical connection between the magnetic sensing devices has to be done in two-stages. In addition, the vertical connection is hard to be standardized, thus the yield is low, failure is more likely to happen and the overall production cost is increased.
Therefore, manufacturers thereof are in an urgent to develop a sensor structure with a smaller size, in which the magnetic sensing devices of three directions thereof are placed on the same plane, to resolve the manufacturing problems mentioned above.
The primary purpose of the present invention is to provide a planarized 3D magnetic sensor chip, including a circuit chip substrate, a first magnetic sensing device, a second magnetic sensing device, a third magnetic sensing device and a magnetic bending concentrating structure. The first, second and third magnetic sensing devices and the magnetic bending concentrating structure are disposed on the top surface of the circuit chip substrate, and are electrically connected with a circuit in the circuit chip substrate. The second magnetic sensing device cooperatively measures the magnitude of a magnetic flux in a first direction and a third direction with the first magnetic sensing device. The third magnetic sensing device measures the magnitude of the magnetic flux in a second direction, where the second direction is vertical to the first direction with respect to a plane, and the third direction is vertical to the first and second direction.
The magnetic bending concentrating structure is disposed between the first and second magnetic sensors, so as to concentrate and bend the magnetic flux in the third direction to the first direction. In this way, the magnetic flux magnitude in the third direction can be measured by the first and second magnetic sensing device in the first direction.
Furthermore, a set of fourth magnetic sensing device and fifth magnetic sensing device can be utilized to replace the third magnetic sensing device. The magnetic flux bending concentrating structure is disposed between the first and second magnetic sensing device, and/or is disposed between the fourth and fifth magnetic sensing device. The magnetic flux bending concentrating structure concentrates and bends the magnetic flux in the third direction to the first direction, so the magnetic flux magnitude in the third direction can be measured by the first and second magnetic sensing device in the first direction, or the magnetic flux magnitude in the third direction can be measured by the fourth and fifth magnetic sensing device in the second direction.
The magnetic bending concentrating structure can be manufactured with the first, second and third magnetic sensing device (or with the fourth and fifth magnetic sensing device) by the semiconductor manufacture method. Alternatively, the magnetic bending concentrating structure can be prepared beforehand and then cut and placed at intended positions. The magnetic bending concentrating structure can also be formed via physical or chemical deposition and etching, or can also be implemented with embedded structure. By bending the magnetic flux, the magnetic flux magnitudes in three dimensions can be measured on a plane, instead of the conventional method where a 2-steps manufacturing method is needed to install a magnetic sensing device in a third direction. In this way, the yield and production rate of the magnetic sensor can be greatly improved.
The present invention will be apparent to those skilled in the art by reading the following detailed description of preferred embodiments thereof, with reference to the attached drawings.
Understandably, when the first magnetic sensing device 21, the second magnetic sensing device 23, the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33 are in use, and the first magnetic sensing device 21 and the second magnetic sensing device 23 are arranged in the same direction, the magnetic flux magnitude in the first or second direction can be the sum of the measured magnetic flux magnitudes, and the magnetic flux magnitude in the third direction can be the difference between the measured magnetic flux magnitudes. On the contrary, when the first magnetic sensing device 21 and the magnetic sensing device 23 are arranged in the opposite direction, the magnetic flux magnitude in the first or second direction can be the difference between the measured magnetic flux magnitudes, and the magnetic flux magnitude in the third direction can be the sum of the measured magnetic flux magnitudes. When the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33 are arranged in the same direction, the magnetic flux magnitude in the second or the first direction can be the sum of the measured magnetic flux magnitudes; while the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33 are arranged in the opposite direction, the magnetic flux magnitude in the first or second direction can be the difference between the measured magnetic flux magnitudes.
Similarly, when the first magnetic sensing device 21, the second magnetic sensing device 23, the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33 are in use, and the first magnetic sensing device 21 and the second magnetic sensing device 23 are arranged in the same direction, the magnetic flux magnitude in the first or second direction can be the sum of the measured magnetic flux magnitudes; while the first magnetic sensing device 21 and the second magnetic sensing device 23 are arranged in the opposite direction, the magnetic flux magnitudes in the first or second direction can be the difference between the measured magnetic flux magnitudes. When the fourth magnetic sensing device 31 and the fifth magnetic sensing device are arranged in the same direction, the magnetic flux magnitudes in the first or second direction can be the sum of the measured magnetic flux magnitudes, and the magnetic flux magnitude in the third direction can be the difference between the measured magnetic flux magnitudes. On the contrary, when the fourth magnetic sensing device 31 and the fifth magnetic sensing device are arranged in the opposite direction, the magnetic flux magnitudes in the first or second direction can be the difference between the measured magnetic flux magnitudes, and the magnetic flux magnitude in the third direction can be the sum of the measured magnetic flux magnitudes.
The first magnetic sensing device 21 and the second magnetic sensing device 23, the third magnetic sensing device 30 (or, the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33) can be at least one of a anisotropic magnetic resistance (AMR) element, a giant magnetic resistance (GMR) element, and a tunneling magnetic reluctance (TMR) element. Each magnetic sensing device forms a bridge configuration independently first and then are electrically connected to each other, or are connected in series. For example, the first magnetic sensing device 21 and the second magnetic sensing device 23 are connected to each other to form the bridge configuration first, and then are electrically connected to the third magnetic sensing device 30 which forms the independent bridge configuration, or are electrically connected to the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33 which are connected to each other.
The first magnetic sensing device 21 and the second magnetic sensing device 23, the third magnetic sensing device 30 (or, the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33) can be manufactured independently before they are assembled onto the circuit chip substrate 10. Alternatively, they can also be directly formed on the circuit chip substrate 10 via physical or chemical deposition and etching process.
A bottom surface of the magnetic flux bending concentrating structure 40 is on the same level with, slightly higher or slightly lower than the surface of the first magnetic sensing device 21, the second magnetic sensing device 23 and the third magnetic sensing device 30 (or, the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33). The magnetic flux bending concentrating structure 40 has a columnar shape, and is one of a solid cylinder, a corner pillar or a polygon pillar with any ratio of width and height. The magnetic flux bending concentrating structure 40 is a metallic magnetic material or a ceramic magnetic material, and a permeability of the magnetic flux bending concentrating structure 40 is 110000 H/m. The metallic magnetic material is at least one selected from a group consisting of iron, cobalt, nickel, iron-cobalt alloy, cobalt-nickel alloy, iron-nickel alloy, iron-cobalt-nickel alloy and cobalt-iron-boron compounds. The ceramic magnetic material is ferrimagnets, and the crystal structure of the ceramic magnetic material is at least one of the spinel, anti-spinel and perovskite.
The magnetic flux bending concentrating structure 40 is prepared beforehand and then is cut to be placed at intended position on the circuit chip substrate 10, or, the magnetic flux bending concentrating structure 40 can be formed on the circuit chip substrate 10 directly via physical or chemical deposition and etching. For example, multiple columnar holes are etched on the circuit chip substrate 10 first, and then the columnar holes are filled up with physical or chemical deposition method.
The present invention is characterized in that the magnetic flux bending concentrating structure 40 can be manufactured together with the first magnetic sensing device 21, the second magnetic sensing device 23 and the third magnetic sensing device 30 (or, the fourth magnetic sensing device 31 and the fifth magnetic sensing device 33) that measures the magnetic flux magnitude in the first and second directions via semiconductor manufacturing method. By bending the magnetic flux, the magnetic flux magnitudes in three directions can be measured on a plane, thereby emitting the conventional magnetic sensors which requires the 2-steps manufacturing method to install a magnetic sensing device in the third direction. In this way, the production rate and the yield of the magnetic sensors can be greatly improved.
The preferred embodiment described above is disclosed for illustrative purpose but to limit the modifications and variations of the present invention. Thus, any modifications and variations made without departing from the spirit and scope of the invention should still be covered by the scope of this invention as disclosed in the accompanying claims.