HALL SENSOR AND METHOD OF MANUFACTURING THE SAME

Disclosed herein are a Hall sensor and a method of manufacturing the Hall sensor. The Hall sensor includes: a flexible substrate in which a groove is formed; a magnetic field flux concentrator formed in the groove of the flexible substrate; an electrode that is patterned to contact the magnetic field flux concentrator; a passivation layer formed around the electrode; and a sensor layer stacked on the passivation layer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The objects, features, and advantages of the present invention will be more clearly understood from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant descriptions thereof are omitted. Further, in the following description, the terms “first”, “second”, “one side”, “the other side” and the like are used to differentiate a certain component from other components, but the configuration of such components should not be construed to be limited by the terms. Further, in the description of the present invention, when it is determined that the detailed description of the related art would obscure the gist of the present invention, the description thereof will be omitted.

FIG. 1is a cross-sectional view of a Hall sensor according to an embodiment of the present invention.

Referring toFIG. 1, the Hall sensor according to the current embodiment of the present invention includes a flexible substrate10in which a groove (11) is formed, a magnetic field flux concentrator12which is formed in the groove (11) of the flexible substrate10, an electrode14that is stacked on the magnetic field flux concentrator12and is patterned, a passivation layer16formed around the electrode14, a sensor layer18that is stacked on the passivation layer16, and a molding layer20surrounding the passivation layer16and the sensor layer18.

The flexible substrate10is a substrate having flexibility and includes a polymer.

Here, a polymer refers to both a thermosetting resin and a thermal reinforced resin, and preferably, the flexible substrate10is characterized in that it is a thermosetting resin that is hardened when heat is applied thereto and has flexibility. Depending on the fields to which the present invention is applied, a polymer selected from the group consisting of polyethylene terephthalate (PET), polyethylene sulfide (PES), polyethylene naphthalate (PEN), polycarbonate (PC), nylon, polyether ether ketone (PEEK), polysulfone (PSF), polyetherimide (PEI), polyacrylate (PAR), polybutylene terephthalate (PBT), and ARTON formed of a norbonene resin having a polarity may be used the polymer.

A groove11is formed in an upper portion of the flexible substrate10to mount the magnetic field flux concentrator12.

Next, the magnetic field flux concentrator12is mounted in the groove11of the flexible substrate10so that a magnetic field is concentrated on the sensor layer18to increase sensitivity of the Hall sensor.

Meanwhile, the passivation layer16is disposed between the magnetic field flux concentrator12and a sensor device (formed of an electrode14and the sensor layer18), and surrounds the electrode14of the sensor device to protect the electrode14from the external environments.

The passivation layer16may preferably be formed of SiN, SiON, or SiO2.

Meanwhile, the electrode14is disposed between the magnetic field flux concentrator12and the sensor layer18, and is usually an ohmic electrode, and may preferably be in ohmic contact with the sensor layer18. The electrode14may be formed of a multi-layer electrode such as AuGe/Ni/Au that is well-known in the art, and may also be formed of a single-layer metal.

In addition, the sensor layer18includes a second compound semiconductor layer18-2that is formed of InxGa1-xAsySb1-y (0<x≦1.0, 0≦y≦1.0) on the passivation layer16.

In addition, a first compound semiconductor layer18-1formed of at least two elements selected from the group consisting of Ga, Al, In, As, Sb, and P on the second compound semiconductor layer18-2.

(111) surfaces of the first compound semiconductor layer18-1and the second compound semiconductor layer18-2are formed to be parallel to a surface of the magnetic field flux concentrator12.

The first compound semiconductor layer18-1is formed of a compound semiconductor formed of at least two elements selected from the group consisting of Ga, Al, In, As, Sb, and P, and generally has a thickness of 0.01 μm to 10 μm, preferably, 0.1 μm to 5 μm, and more preferably, 0.5 μm to 2 μm. Al1-zGazAs (0≦z≦1) is a preferable example for the material for the first compound semiconductor layer18-1, and GaAs is particularly preferable.

Also, the second compound semiconductor layer18-2is formed of InxGa1-xAsySb1-y (0≦y≦1), and generally has a thickness of 0.1 μm; if the thickness is thicker, sheet resistance is reduced. When forming a sensor device having a high sensitivity and a relatively high resistance, the thickness of the second compound semiconductor layer18-2is generally 0.15 μm to 2 μm, preferably, 0.3 μm to 1.5 μm, and more preferably, 0.5 μm to 1.2 μm. InAsySb1-y (0≦y≦1) is a preferable example as the material for the second compound semiconductor layer18-2, and InSb or InAs is particularly preferable.

Also, the second compound semiconductor layer18-2may also be doped with impurities. Preferable examples of a doping element are Si and Sn. A concentration of the impurities may be generally 1×E15/cm3to 3.5×E16/cm3, preferably, 2.5×E15/cm3to2.5×E16/cm3, and more preferably, 5×E15/cm3to 2×E16/cm3.

Meanwhile, the molding layer20is formed to surround the sensor layer18, the passivation layer16, and an exposed portion of the flexible substrate10.

According to the Hall sensor configured as described above, the sensor device may be deposited on a rigid substrate on the flexible substrate10at a high temperature, and thus performance of the sensor device may be enhanced.

Also, according to the present invention, when manufacturing the flexible substrate10, the magnetic field flux concentrator12may be formed in advance when hardening a polymer, and thus the manufacturing process may be simplified.

In addition, according to the present invention, as a passivation layer for surrounding the magnetic field flux concentrator12is not necessary, costs may be reduced and the process may be simplified.

FIGS. 2 through 10are views illustrating a method of manufacturing a Hall sensor according to an embodiment of the present invention.

Referring toFIG. 2, first, a sacrificial layer110is deposited on a carrier substrate100.

Here, the carrier substrate100allows to stably deposit a sensor device, and then, when the sensor device is mounted on a flexible substrate, the carrier substrate100is to be removed by using a laser lift off method, and a rigid substrate is formed of MgO or Al2O3.

In addition, the sacrificial layer110is used to separate the carrier substrate100from the sensor device when the manufacture of the sensor device is completed. The sacrificial layer110may be formed by using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. Preferably, the sacrificial layer110may be formed by using a sputtering method, which is one kind of PVD method.

The sacrificial layer110may be formed of a material that is capable of absorbing various types of excimer lasers having a wavelength of157nm to350nm and is a non-conductor material such as a GaO, GaN, or GaON based material, or lead zirconate titanate (PZT), ZrO2, and preferably, the sacrificial layer110may be formed of GaON.

Next, as illustrated inFIG. 3, a sensor layer120formed of the first compound semiconductor layer120-1and the second compound semiconductor layer120-2is formed on the sacrificial layer110.

In further detail, the first compound semiconductor layer120-1is formed of GaAs on the sacrificial layer110to a thickness of700nm and the second compound semiconductor layer120-2is formed of InSb also thereon to a thickness of 1 μm. The first compound semiconductor layer120-1is formed of a compound semiconductor formed of at least two elements selected from the group consisting of Ga, Al, In, As, Sb, and P, and generally has a thickness of 0.01 μm to 10 μm, preferably, 0.1 μm to 5 μm, and more preferably, 0.5 μm to 2 μm. Al1-zGazAs (0≦z≦1) is a preferable example for the material for the first compound semiconductor layer120-1, and GaAs is particularly preferable.

Also, the second compound semiconductor layer120-2is formed of InxGa1-xAsySb1-y (0≦y≦1), and generally has a thickness of 0.1 μm; if the thickness is thicker, sheet resistance is reduced. When forming a sensor device having high sensitivity and relatively high resistance, the thickness of the second compound semiconductor layer120-2is generally 0.15 μm to 2 μm, preferably, 0.3 μm to 1.5 μm, and more preferably, 0.5 μm to 1.2 μm. InAsySb1-y (0≦y≦1) is a preferable example as the material for the second compound semiconductor layer120-2, and InSb or InAs is particularly preferable.

Also, the second compound semiconductor layer120-2may also be doped with impurities. Preferable examples of a doping element are Si and Sn. A density of the impurities may be generally 1×E15/cm3to 3.5×E16/cm3, preferably, 2×E15/cm3to 2.5×E16/cm3, and more preferably, 5×E15/cm3to 2×E16/cm3.

The sensor layer120may be formed by using a CVD method or a PVD method. Preferably, the sensor layer120may be formed by using a sputtering method, which is one kind of the PVD method.

Next, as illustrated inFIG. 4, an electrode layer130is formed on the sensor layer120using a plating method or the like, and as illustrated inFIG. 5, a mask is used to pattern (the electrode layer130) to form a patterned electrode132.

The electrode may be formed of a multi-layer electrode such as AuGe/Ni/Au which is well-known in the art, or may also be a single-layer metal.

Next, as illustrated inFIG. 6, in order to protect the patterned electrode132, a passivation layer140is deposited.

The passivation layer140may preferably be formed of SiN, SiON, or SiO2.

The passivation layer140may be formed by using a CVD method or a PVD method. Preferably, the passivation layer140may be formed by using a sputtering method which is one kind of PVD method.

Meanwhile, during the above operation, a flexible substrate200is additionally or simultaneously prepared.

Here, as illustrated inFIG. 7, a groove is formed in the prepared flexible substrate200, and a magnetic field flux concentrator210is included in the groove. A formation process thereof will be described in detail below with reference toFIGS. 11 through 14.

Next, as illustrated inFIG. 8, a surface of the Hall sensor on which the electrode132is formed is placed to face the flexible substrate200, and then, the sensor device formed on the carrier substrate100(the sensor device includes a sensor layer and an electrode) is bonded to the flexible substrate.

Next, as illustrated inFIG. 9, a laser such as ArF, KrCl, KrF, XeCl, or XeF is irradiated to separate an interface between the carrier substrate100and the sacrificial layer110. When a laser is irradiated on the carrier substrate100, an energy band gap of the carrier substrate100is greater than a wavelength of the laser, and accordingly, the irradiated laser may easily pass through the carrier substrate100to be absorbed by the sacrificial layer110. When the laser is irradiated, plasma is generated between the carrier substrate100and the sacrificial layer110, and the plasma having a high temperature increases a temperature of the interface between the carrier substrate100and the sacrificial layer110, thereby setting the sacrificial layer110in a partially melted state.

Here, in addition to the partial melting due to the high temperature of the plasma, a nitrogen (N2) gas is generated, and gasification of the nitrogen gas exfoliates the interface between the carrier substrate100and the sacrificial layer110. Preferably, when forming the sacrificial layer110, a reactive hydrogen gas112may be injected when forming the sacrificial layer110, and in a laser lift off operation, partial melting of the sacrificial layer110according to the high temperature of the plasma generates nitrogen gas N2, and according to gasification of the hydrogen gas H2, the interface between the sacrificial layer110and the carrier substrate100is furthermore easily exfoliated.

As described above, when the sacrificial layer110is separated from the carrier substrate100, as illustrated inFIG. 10, the sacrificial layer110attached on the sensor device is completely removed by ion milling, thereby completing the Hall sensor. Thereafter, the Hall sensor may be molded by coating a molding layer220.

The Hall sensor that is completed as described above may have not only high sensor performance compared to other devices; moreover, when bonding a magnetic field flux concentrator, the magnetic field flux concentrator may also be easily fixed by hardening when manufacturing a flexible substrate. Accordingly, the Hall sensor may have far better workability compared to a flexible device according to the conventional art.

Meanwhile,FIGS. 11 through 14are views illustrating a method of manufacturing a flexible substrate on which the magnetic field flux concentrator210provided inFIG. 8is formed.

Next, as illustrated inFIG. 12, the magnetic field flux concentrator210is installed to be located in a center of the groove310of the mold300.

Then, as illustrated inFIG. 13, a solution320for a flexible substrate is injected into the groove310of the mold300so as to fill the groove310.

Here, the solution for a flexible substrate may include a polymer, and the polymer refers to both a thermosetting resin and a thermal reinforced resin; preferably, the polymer is characterized in that it is a thermosetting resin that is hardened when heat is applied thereto and has flexibility. Depending on the fields to which the present invention is applied, a polymer selected from the group consisting of polyethylene terephthalate (PET), polyethylene sulfide (PES), polyethylene naphthalene (PEN), polycarbonate (PC), nylon, polyether ether ketone (PEEK), polysulfone (PSF), polyetherimide (PEI), polyacrylate (PAR), polybutylene terephthalate (PBT), and ARTON formed of a norbonene resin having a polarity may be used as the polymer.

Then, as illustrated inFIG. 14, after the solution320for a flexible substrate is hardened, the mold300is separated to obtain the flexible substrate200in which the magnetic field flux concentrator210is buried.

According to the present invention, the sensor device may be deposited on a rigid substrate at a high temperature, and thus, performance of the sensor device may be enhanced.

Also, according to the present invention, when manufacturing the flexible substrate, as the magnetic field flux concentrator may be formed in advance when hardening a polymer, the manufacturing process may be simplified.

In addition, according to the present invention, as a passivation layer for surrounding the magnetic field flux concentrator is not necessary, costs may be reduced and the process may be simplified.