Patent Description:
Various parameters characterize the performance of current sensors, including sensitivity. Sensitivity is related to the magnitude of a change in output voltage from the sensing element in response to a sensed current. The sensitivity of a current sensor can be influenced by a variety of factors, including is a physical distance between the sensing element and the conductor.

Integration of the current sensor, including the sensing element and the conductor into an integrated circuit (IC) package calls for close and precise positioning of the current conductor relative to the sensing element. Thus, voltage noise that is capacitively coupled from the current conductor can adversely impact the performance and output of the sensing element and the current sensor causing an unwanted or inaccurate response. <CIT> discloses a miniaturized current sensor in an integrated circuit package. <CIT> discloses a current conductor provided with opposing notches to produce a restricted section and with magnetic flux sensors on opposite sides of the restricted current section. <CIT> discloses an integrated current sensor including a current conductor, a magnetic field transducer, and an electromagnetic shield.

Systems described herein are directed towards integrating a shield layer into a current sensor. The present invention provides a current sensor according to claim <NUM>. Other embodiments are defined in the dependent claims. In a current sensor, noise from external sources and internal sources, such as between different components of the current sensor, can impact the output and performance of the current sensor. For example, in a current sensor, having a die supporting a magnetic field sensing element and associated circuitry and a current carrying conductor (e.g. lead frame), the die and the current carrying conductor can form two plates of a parasitic capacitor. This capacitance can lead to the coupling of electrical, voltage, or electrical transient noise from the conductor to the die during large transient (dV/dt) events on the conductor. In accordance with the invention, the shield layer is disposed between the die and the conductor to shunt this noise to ground, and one plate of the capacitor is tied to ground through the shield layer.

The shield layer is disposed along at least one surface of a die supporting a magnetic field sensing element to shield the magnetic field sensing element and associated circuitry from external noise and internal noise, such as may be capacitively coupled from a current carrying conductor in the current sensor. In some embodiments, having a die up configuration, the shield layer may be disposed along a back side of the die and proximal to the current carrying conductor.

In other embodiments, such as those having a flip chip configuration, the shield layer may be disposed on a surface of the die supporting the magnetic field sensing element proximate to the current carrying conductor. The shield layer may include an aperture (or other features to enable high frequency magnetic fields to reach the sensing element) to reduce eddy currents. In some embodiments having a dual die assembly, a first die may be disposed between the current carrying conductor and a second die supporting the magnetic field sensing element. The first die may include shield and insulation layers to reduce a noise experienced by the magnetic field sensing element and circuitry.

The shield layer can be integrated into the current sensor using various techniques, including but not limited to, through hole silicon vias, stacked die arrangements, and/or wafer bonding, and be configured to prevent coupling noise onto the die during high transient (dV/dt) events in the current carrying conductor.

In an embodiment, the current sensor can be provided in the form of an integrated circuit having a lead frame. The conductor may comprise a first portion of the lead frame and a plurality of signal leads may comprise a second portion of the lead frame. The current sensor may include an interconnect configured to couple the via to at least one of the plurality of signal leads. In some embodiments, the interconnect may include a wire bond.

The magnetic field sensing element may comprise at least one of a Hall-effect element or a magnetoresistance element. The insulation layer may include at least one of a polymer dielectric material, a polyimide film or a layer of adhesive. The shield layer may comprise a conductive material, and may include at least one of copper, aluminum, gold, nickel or aluminum copper alloy, etc..

In some embodiments, the via comprises a through-silicon via extending from the first surface of the semiconductor substrate to the second surface of the semiconductor substrate.

In an embodiment, the first surface of the semiconductor substrate may support the magnetic field sensing circuit. The shield layer may include an aperture or slot aligned with the magnetic field sensing element. Such a slot may reduce a property of an eddy current as sensed by the magnetic field sensing element.

In another example not claimed herein, the present disclosure is directed towards a current sensor having a conductor and a first die having a first surface proximal to the conductor and a second opposing surface distal from the conductor. The first die may include a shield layer. The current sensor may further include a second die having a first surface proximal to the first die and a second opposing surface distal from the first die and supporting a magnetic field sensing circuit.

In this example, the first die may comprise a substrate having first and second opposing surfaces; a shield layer having a first surface proximal to the second surface of the substrate and having a second opposing surface; and a protective layer having a first surface proximal to the second surface of the shield layer and having a second opposing surface. The current sensor may comprise a first insulation layer having a first surface proximal to the second surface of the substrate and having a second opposing surface. In another example, the first die may include a semiconductor substrate having first and second opposing surfaces, a protective layer having a first surface proximal to the second surface of the semiconductor substrate and having a second opposing surface, the shield layer having a first surface proximal to the second surface of the protective layer and having a second opposing surface and a first insulation layer having a first surface proximal to the second surface of the shield layer and having a second opposing surface. In some examples, a bond pad may be in contact with the shield layer and exposed through an aperture in the first insulation layer, or in the protective layer.

In this example, the current sensor may be provided in the form of an integrated circuit having a lead frame. The conductor may comprise a first portion of the lead frame and a plurality of signal leads may comprise a second portion of the lead frame and the current sensor may further comprise a wire bond coupled between the bond pad and at least one of the signal leads.

In this example, the substrate may be at least one of a semiconductor substrate or an insulating substrate. In some examples, the semiconductor substrate may include silicon. The insulating substrate may comprise Alumina or glass. The protective layer, or the first insulation layer, may include silicon oxide, silicon dioxide, or a combination thereof. The shield layer may include at least one of copper, aluminum or gold. The first insulation layer may include benzo-cyclobutene (BCB) or a polymer dielectric material.

In this example, the magnetic field sensing circuit may include a magnetic field sensing element comprising at least one of a Hall-effect element or a magnetoresistance element. The first die may include a second insulation layer disposed between the conductor and the substrate, which may be a semiconductor substrate. The first insulation layer may comprise one or more layers of insulation. In one example, the second insulation layer may include a flex circuit having a layer of Kapton® and a metalized layer. The second insulation layer may include at least one of a polymer dielectric material, a polyimide film or a layer of adhesive.

In one example, the first die may be larger than the conductor and have at least one edge that extends beyond an edge of the conductor. In some examples, the first die may be larger than the second die and have at least one edge that extends beyond an edge of the second die. In some examples, the first die has a length defined by a first and second edge and the shield layer does not extend to at least one of the first or second edge of the first die. The current sensor may be provided in the form of an integrated circuit having a lead frame. The conductor may include a first portion of the lead frame and a plurality of signal leads may include a second portion of the lead frame, and the at least one edge of the first die may extend beyond an edge of at least one of the signal leads. In some examples, a first epoxy layer is disposed between the conductor and the first surface of the first die and a second epoxy layer is disposed between the second surface of the first die and the first surface of the second die.

In another example not claimed herein, the present disclosure is directed towards a current sensor having a conductor, an insulation layer in contact with the conductor, a shield layer comprising at least one of a metalized tape or a metalized Mylar® spaced from the conductor by the insulation layer and a semiconductor substrate having a first surface disposed proximal to the shield layer and a second opposing surface disposed distal from the shield layer and supporting a magnetic field sensing element.

The magnetic field sensing element may include at least one of a Hall-effect element or a magnetoresistance element. The current sensor may be provided in the form of an integrated circuit having a lead frame. The conductor may include a first portion of the lead frame and a plurality of signal leads may include a second portion of the lead frame. In some examples, the current sensor may include a wire bond configured to couple the shield layer to at least one of the plurality of signal leads.

In this example, the current sensor may include a via extending through the semiconductor substrate to couple the shield layer to the second surface of the semiconductor substrate. The current sensor may include an interconnect configured to couple the via to at least one of the plurality of signal leads.

In this example, the current sensor may include a conductive epoxy disposed between the shield layer and the semiconductor substrate and along at least one side of the semiconductor substrate between the first and second surfaces of the substrate.

In another not claimed herein, the present disclosure is directed towards a current sensor having a first die having a first surface and a second opposing surface supporting a conductor in the form of a coil and a second die having a first surface on which a shield layer is formed and a second opposing surface. The shield layer may include an aperture configured to reduce eddy currents and the shield layer may be spaced from the second surface of the first die by an airgap. The aperture (e.g., cuts, slits, slots or other similar features) may enable high frequency magnetic fields to reach the sensing element.

In some examples, the shield layer comprises a first shield layer and the second die may include a protective layer having a first surface proximal to the first shield layer and a second opposing surface, a semiconductor substrate having a first surface proximal to the protective layer and a second opposing surface, and a second shield layer having a first surface proximal to the semiconductor substrate and a second opposing surface.

In this example, the protective layer may support the magnetic field sensing element. The magnetic field sensing element may comprise at least one of a Hall-effect element or a magnetoresistance element. The first die may include a third shield layer proximal to the first surface of the first die.

The foregoing features may be more fully understood from the following description of the drawings in which <FIG> show arrangements according to the invention, and <FIG> show other arrangements not forming part of the claimed subject matter. In particular:.

Before describing the present invention, some introductory concepts and terminology are explained.

As used herein, the term "magnetic field sensing element" is used to describe a variety of electronic elements that can sense a magnetic field. The magnetic field sensing element can be, but is not limited to, a Hall-effect element, a magnetoresistance element, or a magnetotransistor. As is known, there are different types of Hall-effect elements, for example, a planar Hall element, a vertical Hall element, and a Circular Vertical Hall (CVH) element. As is also known, there are different types of magnetoresistance elements, for example, a semiconductor magnetoresistance element such as Indium Antimonide (InSb), a giant magnetoresistance (GMR) element, for example, a spin valve, an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance (TMR) element, and a magnetic tunnel junction (MTJ). The magnetic field sensing element may be a single element or, alternatively, may include two or more magnetic field sensing elements arranged in various configurations, e.g., a half bridge or full (Wheatstone) bridge. Depending on the device type and other application requirements, the magnetic field sensing element may be a device made of a type IV semiconductor material such as Silicon (Si) or Germanium (Ge), or a type III-V semiconductor material like Gallium-Arsenide (GaAs) or an Indium compound, e.g., Indium-Antimonide (InSb).

As is known, some of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity parallel to a substrate that supports the magnetic field sensing element, and others of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity perpendicular to a substrate that supports the magnetic field sensing element. In particular, planar Hall elements tend to have axes of sensitivity perpendicular to a substrate, while metal based or metallic magnetoresistance elements (e.g., GMR, TMR, AMR) and vertical Hall elements tend to have axes of sensitivity parallel to a substrate.

As used herein, the term "magnetic field sensing circuit" is used to describe a circuit that uses a magnetic field sensing element, generally in combination with other circuits. Magnetic field sensing circuits are used in a variety of applications, including, but not limited to, an angle sensor that senses an angle of a direction of a magnetic field, a current sensor that senses a magnetic field generated by a current carried by a current-carrying conductor, a magnetic switch that senses the proximity of a ferromagnetic object, a rotation detector that senses passing ferromagnetic articles, for example, magnetic domains of a ring magnet or a ferromagnetic target (e.g., gear teeth) where the magnetic field sensor is used in combination with a back-biased or other magnet, and a magnetic field sensor that senses a magnetic field density of a magnetic field.

Referring to <FIG>, a current sensor <NUM> is provided with a shield layer <NUM> to reduce the effects of electrical, voltage, or electrical transient noise coupled to active circuitry within the current sensor <NUM> through parasitic capacitance between a conductor portion and the circuitry. The current sensor <NUM> includes a conductor <NUM>, an insulation layer <NUM> in contact with the conductor <NUM> and a semiconductor substrate <NUM> having a shield layer <NUM> disposed on a first surface 110a proximal to the insulation layer <NUM> and a second opposing surface 110b distal from the insulation layer <NUM>. The current sensor <NUM> further includes a magnetic field sensing circuit, including a magnetic sensing element <NUM>, supported by the semiconductor substrate <NUM> and a via <NUM> extending through the semiconductor substrate <NUM> to couple the shield layer <NUM> to the second surface 110b of the semiconductor substrate <NUM>. The shield layer <NUM> is coupled to a reference potential.

In an embodiment, current sensor <NUM> has a die up configuration. Die up assembly may refer to a current sensor having a magnetic field sensing element <NUM> and associated circuitry on a surface (here a top surface 110b) of the substrate <NUM> distal from the current conductor <NUM>. For example, and still referring to <FIG>, a first surface 110a of the semiconductor substrate <NUM> is disposed on the shield layer <NUM> and proximal to the conductor <NUM>. A second surface 110b supports a magnetic field sensing element <NUM> and is distal from the conductor <NUM>. Thus, the second surface 110b may be referred to as an active surface and the first surface 110a may be referred to as a back surface.

The magnetic field sensing element <NUM> may be diffused into the second surface 110b or otherwise disposed on or supported by the second surface 110b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

The magnetic field sensing element <NUM> may include a Hall-effect element or magnetoresistance elements. For example, the magnetoresistance elements may include at least one of Indium Antimonide (InSb), a giant magnetoresistance (GMR) element, an anisotropic magnetoresistance (AMR) element, a tunneling magnetoresistance (TMR) element or a magnetic tunnel junction (MTJ) element. The magnetoresistance elements can be very sensitive and therefore, in some embodiments, the die up assembly design may be used for current sensors <NUM> having a magnetoresistance element to create a larger distance between the magnetoresistance element and a current carrying conductor <NUM>.

In some embodiments, during manufacture of the current sensor <NUM>, the magnetoresistance element <NUM> may be deposited on a silicon layer as part of a final processing step making a top layer metal shield (adjacent to the second active surface 110b), difficult to accomplish without damaging the magnetoresistance element. Thus, the use of the backside shield layer <NUM> disposed between the semiconductor substrate <NUM> and the insulation layer <NUM> (and before the magnetic field sensing element <NUM>), allows for a metal shield layer to be added to the current sensor <NUM> without damaging the magnetoresistance element.

In an embodiment, the current sensor <NUM> may be provided as an integrated circuit (IC) having a lead frame. The lead frame may have two portions, a first portion for carrying a primary current to be detected and a second portion for carrying signals to and from the current sensor. For example, the first portion of the lead frame may provide the conductor <NUM> and the second portion of the lead frame may comprise a plurality of signal leads <NUM>.

The lead frame may be formed from various materials and by various techniques, such as stamping or etching. As one example, the lead frame is a copper lead frame pre-plated with NiPdAu. Other suitable materials for the lead frame include but are not limited to aluminum, copper, copper alloys, titanium, tungsten, chromium, Kovar™, nickel, or alloys of the metals. Furthermore, the lead frame may be comprised of a non-conductive substrate material, such as a standard PC board with FR-<NUM> and copper traces, or a Kapton material with copper or other metal traces (for example a flexible circuit board). The lead and lead frame dimensions can be readily varied to suit particular application requirements.

The substrate <NUM> may be electrically coupled to at least one signal lead <NUM> (i.e. lead frame) through an interconnect <NUM>. In some embodiments, the second active surface 110b may be coupled to a signal lead <NUM> through the interconnect <NUM>. In an embodiment, the interconnect <NUM> may be a wire bond coupled between a bond pad on the second active surface 110b and the signal lead <NUM>, as shown.

The shield layer <NUM> can be disposed over or under the first surface 110a (e.g. backside metal shield) of the semiconductor substrate <NUM>. In some embodiments, the shield layer <NUM> may be applied to or otherwise coated on the first surface 110a of the substrate <NUM>. For example, the shield layer <NUM> may be plated on the first surface 110a. In other embodiments, the shield layer <NUM> may be formed on the insulation layer <NUM> and the substrate <NUM> attached to the shield layer <NUM>.

In operation, the shield layer <NUM> which is electrically coupled to a reference potential, serves to tie one plate of undesirable parasitic capacitance between the conductor <NUM> and substrate <NUM> to the reference potential. As described herein, a reference potential may refer to a reference voltage including but not limited to a supply voltage (e.g., Vcc), a DC voltage, output voltage or a ground voltage. For example, in one embodiment, the reference potential may couple shield layer <NUM> to a fixed voltage such that noise is absorbed. The shield layer <NUM> may include a conductive material, for example and without limitation, aluminum, copper, gold, nickel, aluminum, aluminum copper alloy or other conductive metal material.

The insulation layer <NUM> is disposed over a first surface of the conductor <NUM> and between the shield layer <NUM> and the conductor <NUM>. In some embodiments, the insulation layer <NUM> may be applied to a first surface (e.g., top surface) of the conductor <NUM> as part of a manufacturing process of the current sensor <NUM>. The insulation layer <NUM> is applied such that it extends beyond a length of the first surface of the conductor <NUM>. For example, a first and/or second edge of the insulation layer <NUM> extends beyond a first and/or second edge (e.g., a length) of the conductor <NUM>, the shield layer <NUM> and the substrate <NUM>.

In an embodiment, the insulation layer <NUM> extends beyond a length of the conductor <NUM>, shield layer <NUM> and substrate <NUM> for creepage and clearance reasons. The term "clearance" refers to the shortest distance through air between two conductive parts such as the primary and secondary leads. The term "creepage" refers to the shortest distance between two conductive parts along the surface of any insulation material common to both parts. The spacing distance between components that are required to withstand a given working voltage may be specified in terms of creepage and clearance. Thus, in some embodiments, to meet a specific standard or need of a particular application of the current sensor <NUM>, the insulation layer <NUM> extends beyond a length of the conductor <NUM>, shield layer <NUM> and substrate <NUM> to meet a clearance and/or creepage requirement and increase a distance between two conductive parts (e.g., conductor <NUM>, substrate <NUM>) of the current sensor <NUM>. The length or distance by which the insulation layer <NUM> extends beyond a length of the conductor <NUM>, shield layer <NUM> and substrate <NUM> may vary based on a particular application.

The insulation layer <NUM> may include a polymer dielectric material. For example, the polymer dielectric material may include a polyimide film, a layer of adhesive material or a combination of polyimide film and adhesive material. In some embodiments, the current sensor <NUM> may include more than one insulation layer <NUM>. For example, the layer of adhesive material may include a tape material with an additional adhesive layer (e.g., nonconductive epoxy, die attach paste) disposed over it to couple to shield layer <NUM>. The layers of the insulation layer <NUM> may include different materials. In other embodiments, each of the multiple insulation layers <NUM> may include the same materials.

In some embodiments, the insulation layer <NUM> may be formed with a taping process. In other embodiments, the lead frame insulation layer <NUM> may be formed with a deposition process, such as on the substrate <NUM>. The deposition process used to form the insulation layer <NUM> can include a variety of processes, including, but not limited to, a screen printing process, a spin depositing process, a sputtering process, a plasma enhanced chemical vapor deposition (PECVD) process, and a low-pressure chemical vapor deposition (LPCVD) process. The screen printing process can result in a substrate insulating layer comprised of a variety of materials, including but not limited to, polymer or ceramic materials. The spin depositing process can result in a substrate insulting layer comprised of a variety of materials, including but not limited to a polymer dielectric film, for example, polyimide (e.g., trade name Pyralin®) or bisbenzocyclobutene (BCB) (e.g., trade name Cyclotene®). The sputtering process can result in the insulting layer <NUM> comprised of a variety of materials, including but not limited to, nitride or oxide. The PECVD process can result in the insulting layer <NUM> comprised of a variety of materials, including but not limited to, nitride or oxide. The LPCVD process can result in the insulting layer <NUM> comprised of a variety of materials, including but not limited to, nitride or oxide.

In an embodiment, the substrate <NUM> may be mounted or otherwise attached to the conductor <NUM>. The substrate <NUM> may be mounted after the shield layer <NUM> has been applied to the first surface 110a of the substrate <NUM> and after the insulation layer <NUM> has been applied to the first surface of the conductor <NUM>. Thus, the shield layer <NUM> can be mounted on or otherwise disposed on the insulation layer <NUM> and make contact with the insulation layer <NUM>. The substrate <NUM> is separated from the conductor <NUM> by at least the shield layer <NUM> and the insulation layer <NUM>.

To couple the shield layer <NUM> to a reference potential and optionally at least one signal lead <NUM>, a via <NUM> is provided, which may be formed in the semiconductor substrate <NUM>. The via <NUM> may be a through-silicon via and can extend through the semiconductor substrate <NUM>, from the first surface 110a to the second surface 110b. The via <NUM> couples the shield layer <NUM> to the second surface 110b (i.e. active surface) of the semiconductor substrate <NUM> and to a reference potential of a magnetic field sensing circuit, which may be supported by the second substrate surface 110b.

The via <NUM> is coupled to a reference potential associated with a magnetic field sensing circuit supported by the substrate <NUM>. The via <NUM> is coupled to the reference potential to tie a plate of the parasitic capacitance between the substrate <NUM> and the conductor <NUM> to the reference potential. Thus, a path is established to shunt interfering coupling (internal noise) due to high transient events to the reference potential.

Now referring to <FIG>, a current sensor <NUM> is provided with a shield layer <NUM> to reduce the effects of electrical, voltage, or electrical transient noise coupled to the active circuitry of the current sensor <NUM> through the parasitic capacitance between a conductor portion and the circuitry. The current sensor <NUM> includes a conductor <NUM>, an insulation layer <NUM> in contact with the conductor <NUM> and a semiconductor substrate <NUM> having a shield layer <NUM> disposed on a first surface 210a proximal to the insulation layer <NUM> and a second opposing surface 210b distal from the insulation layer <NUM>. The current sensor <NUM> further includes a magnetic field sensing circuit, including a magnetic field sensing element <NUM>, supported by the semiconductor substrate <NUM> and a via <NUM> extending through the semiconductor substrate <NUM> to couple the shield layer <NUM> to the second surface 210b of the semiconductor substrate <NUM>. The shield layer <NUM> is coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage).

The current sensor <NUM> may have a die up assembly having the magnetic field sensing element <NUM> and associated circuitry on a surface (here a top, second surface 210b) of the substrate <NUM> distal from the current conductor <NUM>. The semiconductor substrate <NUM> has a first surface 210a disposed proximal to the conductor <NUM> and a second surface 210b that supports a magnetic field sensing element <NUM>, which is distal from the conductor <NUM>. In some embodiments, the second surface 210b may be referred to as an active surface and the first surface 210b may be referred to as a backside surface.

In an embodiment, the magnetic field sensing element <NUM> may include a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance elements may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element.

The magnetic field sensing element <NUM> may be diffused into the second surface 210b or otherwise disposed on or supported by the second surface 310b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

The current sensor <NUM> may be provided as an IC having a lead frame. The lead frame may have a first portion for carrying a primary current to be detected and a second portion for carrying signals to and from the current sensor <NUM>. The first portion of the lead frame may provide the conductor <NUM> and the second portion may comprise a plurality of signal leads <NUM>.

The substrate <NUM> may be electrically coupled to at least one signal lead <NUM> (i.e., lead frame) through an interconnect <NUM>. In some embodiments, the second active surface 210b may be coupled to a signal lead <NUM> through the interconnect <NUM>. The interconnect <NUM> may be a wire bond coupled between a bond pad on the second surface 210b and the signal lead <NUM>. For example, a bond pad may be formed on or disposed on the second surface 210b and connected to the interconnect <NUM> to couple to signal lead <NUM>.

In the illustrative embodiment of <FIG>, the shield layer <NUM> is disposed along the first surface 210a and distal from the magnetic field sensing element <NUM>, thus this assembly may be referred to as back side die shield. The shield layer <NUM> may be applied to or otherwise coated on the first surface 210a of the substrate <NUM>. For example, the shield layer <NUM> may be plated to the first surface 210a. In other embodiments, the shield layer <NUM> may be disposed on the insulation layer <NUM> and the substrate <NUM> may be disposed on the shield layer <NUM>.

In operation, the shield layer <NUM>, which is electrically coupled to a reference potential, serves to tie one plate of undesirable parasitic capacitance between the conductor <NUM> and substrate <NUM> to the reference potential (e.g., ground). The shield layer <NUM> may include a conductive material, for example and without limitation, aluminum, copper, gold, nickel, aluminum copper alloy or other conductive metal material.

The shield layer <NUM> is coupled to a reference potential of a magnetic field sensing circuit, which may be supported by the second surface 210b of the semiconductor substrate <NUM>. The via <NUM> extends through the semiconductor substrate <NUM> to couple the shield layer <NUM> to the second surface 210b of the semiconductor substrate <NUM>. The via <NUM> may be formed within the substrate <NUM>. The via <NUM> may be a through-silicon via and extend from the first surface 210a to the second surface 210b.

The shield layer <NUM> is coupled to the reference potential (e.g., signal lead <NUM>) through the via <NUM>. Thus, the via <NUM> provides a path for one plate of the parasitic capacitance between the conductor <NUM> and the substrate <NUM> to be tied to a ground potential. Thus, a path is established to shunt interfering coupling due to high transient events to the reference potential.

As indicated above, the current sensor <NUM> may be similar to the current sensor <NUM> described above with respect to <FIG>, however, the current sensor <NUM> may have direct bonding. For example, a first interconnect 260a may be used to couple the via <NUM> to at least one signal lead <NUM> and a second interconnect 260b may be used to couple the second surface 210b of the semiconductor substrate <NUM> to at least one signal lead <NUM>. In some embodiments, the via <NUM> and the second surface 210b may be coupled to the same signal lead <NUM>. In other embodiments, the via <NUM> and the second surface 210b may be coupled to different signal leads <NUM>. Thus separate wires (i.e. interconnects 260a, 260b) may be maintained to a reference potential (i.e. ground plane).

In an embodiment, the insulation layer <NUM> may be applied or coated to a first surface of the conductor <NUM>. The insulation layer <NUM> may be disposed on the first surface such that it covers the entire first surface of the conductor <NUM>. In some embodiments, the insulation layer <NUM> may be larger (e.g. width, length) than the conductor <NUM>. A larger insulation layer <NUM> may provide further isolation between secondary circuitry including the magnetic field sensing element <NUM> and the conductor <NUM>. For example, the insulation layer <NUM> may be larger (e.g. width, length) than the conductor <NUM> for creepage and clearance reasons. In some embodiments, to meet a specific standard or need of a particular application of the current sensor <NUM>, the insulation layer <NUM> extends beyond a length of the conductor <NUM>, shield layer <NUM> and substrate <NUM> to meet a clearance and/or creepage requirement and increase a distance between two conductive parts (e.g., conductor <NUM>, substrate <NUM>) of the current sensor <NUM>. The length or distance by which the insulation layer <NUM> extends beyond a length of the conductor <NUM>, shield layer <NUM> and substrate <NUM> may vary based on a particular application.

In this embodiment, the insulation layer <NUM> has at least one edge 230c, 230d that that extends beyond an edge 240c, 240d of the conductor <NUM>. In some embodiments, both a first edge 230c of the insulation layer <NUM> extends beyond a first edge 240c of the conductor <NUM> and a second edge 230d of the insulation layer <NUM> extends beyond second edge 240d of the conductor <NUM>. In an embodiment, the extended edges 230c, 230d of the insulation layer <NUM> may provide further protection (isolation) between secondary and primary sides of the current sensor.

Now referring to <FIG>, a current sensor <NUM> is provided with a shield layer <NUM> to reduce the effects of electrical, voltage, or electrical transient noise coupled to the active circuitry through the parasitic capacitance between a conductor <NUM> and the circuitry. The current sensor <NUM> includes a conductor <NUM>, an insulation layer <NUM> in contact with the conductor <NUM> and a semiconductor substrate <NUM> having a shield layer <NUM> disposed on a first surface 310a proximal to the insulation layer <NUM> and a second opposing surface 310b distal from the insulation layer <NUM>. The current sensor <NUM> further includes a magnetic field sensing circuit, including a magnetic field sensing element <NUM>, supported by the semiconductor substrate <NUM> and a via <NUM> extending through the semiconductor substrate <NUM> to couple the shield layer <NUM> to the second surface 310b of the semiconductor substrate <NUM>. The shield layer <NUM> is coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage).

In an embodiment, the current sensor <NUM> may have a die down configuration. A die down configuration refers to a current sensor having a magnetic field sensing element <NUM> and associated circuitry on a surface (here on a bottom, first surface 310a) of the substrate <NUM> proximal to the current conductor <NUM>. For example, in the illustrative embodiment of <FIG>, the semiconductor substrate <NUM> has a first surface 310a disposed proximal to the conductor <NUM> and a second surface 310b distal to the conductor <NUM>. The magnetic field sensing element <NUM> may be disposed along the first surface 310a and thus proximal from the conductor <NUM>. In some embodiments, the first surface 310a may be referred to as an active surface. A die down assembly may be used in current sensors, where it is important for the magnetic field sensing element <NUM> to be as close the conductor <NUM> as possible.

The magnetic field sensing element <NUM> may be diffused into the first surface 310b or otherwise disposed on or supported by the first surface 310b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

The current sensor <NUM> may be provided as an integrated circuit (IC) having a lead frame. The lead frame may have two portions, a first portion for carrying a primary current to be detected and a second portion for carrying signals to and from the current sensor <NUM>. In an embodiment, the first portion of the lead frame may provide the conductor <NUM> and the second portion of lead frame may comprise a plurality of signal leads <NUM>.

In an embodiment, the shield layer <NUM> and the insulation layer <NUM> can be disposed between the magnetic field sensing element <NUM> (and semiconductor substrate <NUM>) and the conductor <NUM>. The first surface 310a of the semiconductor substrate <NUM> is disposed along a first surface of the shield layer <NUM>. Therefore, the magnetic field sensing element <NUM> is proximal to the shield layer (with respect to the second surface 310b which is distal from the shield layer <NUM>). In some embodiments, this type of shielding may be referred to as top metal shielding as the magnetic field sensing element <NUM> and the active first surface 310a are proximal to the shield layer <NUM>.

The shield layer <NUM> may be applied to or otherwise coated on the first surface 310a of the substrate <NUM>. For example, the shield layer <NUM> may be plated to the first surface 310a. In other embodiments, the shield layer <NUM> may be disposed on the insulation layer <NUM> and the substrate <NUM> may be disposed on the shield layer <NUM>. The insulation layer <NUM> may be applied or otherwise coated to a first surface of the conductor <NUM>. In an embodiment, the shield layer <NUM> may be applied to the substrate <NUM> and the insulation layer <NUM> may be applied to the conductor <NUM> as initial steps in a manufacturing process of current sensor <NUM>. Thus, the shield layer <NUM> may be applied or attached to the insulation layer <NUM> to couple the substrate <NUM> to the conductor <NUM>.

In some embodiments, to limit the amount of eddy currents forming in the shield layer <NUM>, the shield layer <NUM> may include an aperture, hole, or opening <NUM> (e.g., a slot, slit, cut, cross shape opening or any other type of opening to aid in the reduction of eddy currents which may affect magnetic field sensing element <NUM>). For example, and referring briefly to <FIG>, a slit <NUM> can be formed into the shield layer <NUM> such that the slit <NUM> is generally aligned with the magnetic field sensing element <NUM>. In some embodiments, slit <NUM> may be formed such that is not generally aligned (e.g., not centered) or positioned over magnetic field sensing element <NUM>.

In <FIG>, a bottom surface of the shield layer <NUM> is shown. The slit <NUM> may be formed as a cross shape having a center open region that exposes the magnetic field sensing element <NUM> to the insulation layer <NUM> and conductor <NUM> under the insulation layer <NUM>. In some embodiments, the slit <NUM> may have the same dimensions (e.g., length, width) as the magnetic field sensing element <NUM>. In other embodiments, the slit <NUM> may have different dimensions (e.g., smaller dimensions, larger dimensions) than the magnetic field sensing element <NUM>. For example, and as shown in <FIG>, the slit <NUM> may be formed as a cross shape having a center open region that exposes the magnetic field sensing element <NUM> to the insulation layer <NUM> and conductor <NUM> under the insulation layer <NUM>. In some embodiments, connections <NUM> may be formed at the edges of the shield layer <NUM> such that the slots or slits or openings <NUM>, <NUM>, <NUM>, <NUM> are open and/or no conductor portion connects these regions over the magnetic field sensing element <NUM>.

In the illustrative embodiment of <FIG>, the shield layer <NUM> includes four portions <NUM>-<NUM> separated by four slits <NUM>-<NUM>. The four portions <NUM>-<NUM> can be coupled with a conductive region <NUM>. A bonding pad <NUM> may be provided to allow the shield layer <NUM> to be coupled to a reference potential. In some embodiments, a connection may be made to circuitry disposed within or on a layer of semiconductor substrate <NUM> using standard via and/or metallization technology. In the presence of a magnetic field, it will be understood that eddy currents <NUM>-<NUM> can be induced in the shield layer <NUM>. Due to the four slits <NUM>-<NUM>, it will be understood that properties of a current path (i.e., a diameter or a path length) of the closed looped eddy currents <NUM>-<NUM> can be altered. For example, slits <NUM>-<NUM> may be formed such that the diameter of eddy currents paths <NUM>-<NUM>, in an area of magnetic field sensing element <NUM>, may be reduced. In some embodiments, responsive to a reduction of eddy currents <NUM>-<NUM>, a vector or a direction of a magnetic field near magnetic field sensing element <NUM> may be changed. Thus, an effective field from any eddy current <NUM>-<NUM> as measured by magnetic field sensing element <NUM> may be lower than if the slits <NUM>-<NUM> were not present in shield layer <NUM>. In some embodiments, slits <NUM>-<NUM> may be formed such that eddy currents paths <NUM>-<NUM> are eliminated.

It will be understood that the reduced size of the closed loops in which the eddy currents <NUM>-<NUM> travel results in smaller eddy currents <NUM>-<NUM> and a smaller local effect on the AC magnetic field that induced the eddy current. Therefore, the sensitivity of the current sensor <NUM> on which the magnetic field sensing element <NUM> and the shield layer <NUM> are used is less affected by the smaller eddy currents <NUM>-<NUM>. Furthermore, by placing the shield layer <NUM> in relation to the magnetic field sensing element <NUM> as shown, so that the slits <NUM>-<NUM> pass over the magnetic field sensing element <NUM>, it will be understood that the magnetic field associated with any one of the eddy currents <NUM>-<NUM>, tends to form magnetic fields passing through the magnetic field sensing element <NUM> in two directions, canceling over at least a portion of the area of the magnetic field sensing element <NUM>. It will also be appreciated that other shapes, sizes, and configurations of one or more slits in the shield layer <NUM> are possible, such as those shown in <CIT>, assigned to the assignee of the subject application.

Referring back to <FIG>, the via <NUM> may be formed in the semiconductor substrate <NUM>. The via <NUM> may be a through-silicon via and extend from the first surface 310a to the second surface 310b of the semiconductor substrate <NUM>. An interconnect <NUM> may electrically couple the via <NUM> to at least one of the signal leads <NUM>. The shield layer <NUM> is coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage) through the via <NUM>.

Now referring to <FIG>, other arrangements not forming part of the claimed subject matter are described. Referring to <FIG>, a current sensor <NUM> having a dual die assembly, also referred herein as a stacked die assembly, is provided. The current sensor <NUM> includes a conductor <NUM>, a first die <NUM> having a first surface proximal to the conductor <NUM> and a second opposing surface distal from the conductor <NUM> and a second die <NUM> having a first surface 410a proximal to the first die <NUM> and a second opposing surface 410b distal from the first die <NUM> and supporting a magnetic field sensing circuit. The first die <NUM> may include a shield layer <NUM> and as will be described in greater detail below, the first die <NUM> may operate as an insulation layer and/or a shielding layer for the second die <NUM>.

The current sensor <NUM> can be an IC having a lead frame. The lead frame may have two portions, a first portion for carrying a primary current to be detected and a second portion for carrying signals to and from the current sensor. The first portion may provide the conductor <NUM> and the second portion may include a plurality of signal leads <NUM>.

The first die <NUM> may include a substrate <NUM>, a shield layer <NUM> having a first surface proximal to the second surface of the substrate <NUM> and a protective layer <NUM> having a first surface proximal to the second surface of the shield layer and having a second opposing surface.

The first die may include a first insulation layer <NUM> having a first surface proximal to the second surface of the substrate <NUM> and having a second opposing surface. The first insulation layer <NUM> may be disposed between the shield layer <NUM> and the substrate <NUM>. Alternatively, the substrate <NUM> may be an insulating substrate and the first insulation layer <NUM> may not be necessary. In some examples, an additional insulating layer may be disposed on or otherwise formed on a backside of substrate <NUM> such that there is an insulating layer between substrate <NUM> and the conductor <NUM>. The additional layer and first insulation layer <NUM> may include thermal oxide, an LPCVD nitride or oxide, oxide and nitride layers, or other insulating material suitable for a semiconductor process.

The protective layer <NUM> may include a polymer dielectric material (e.g., polyimide material) or benzo-cyclobutene (BCB). The shield layer <NUM> can be disposed over a surface of the protective layer <NUM>. For example, the shield layer <NUM> may be applied to or otherwise coated on a surface of the protective layer <NUM>. Alternatively, the protective layer <NUM> may be applied or otherwise coated on a surface of the shield layer <NUM>.

The shield layer <NUM> may include copper, aluminum or other types of conductive metal materials. The shield layer <NUM> may be applied to or otherwise coated on a first surface of the substrate <NUM>. Alternatively, the shield layer <NUM> may be applied to otherwise coated on a first surface of the insulation layer <NUM>, which is disposed on the first surface of the substrate <NUM>.

The insulation layer <NUM> can be disposed over a first surface of the substrate <NUM>. The insulation layer <NUM> may be applied or coated to the first surface of the substrate <NUM>. The insulation layer <NUM> may include silicon oxide, silicon dioxide or a combination of both. The substrate <NUM> may include a semiconductor material, such as a silicon wafer. Alternatively, the substrate <NUM> may be an insulating substrate and include materials such as Alumina or glass.

A length of the shield layer <NUM> may be less than a length of the first die <NUM> (e.g., the shield layer <NUM> may not extend the full length of the first die <NUM>, also as illustrated in <FIG>). For example, the first die <NUM> may have a length defined by a first and second edge. The shield layer <NUM> may not extend to one of the first edge, second edge or both. The shield layer <NUM> may be the same length as the second die <NUM> and positioned under the second die <NUM>. Alternatively, the length of the shield layer <NUM> may be larger than the length of the second die, for example, to allow the shield layer <NUM> to be bonded to the reference potential though the aperture <NUM> in the protective layer <NUM>. In an example, in which the shield layer <NUM> does not extend a full length of the first die <NUM>, one or more portions of insulation material may be deposited on either or both edges of the shield layer <NUM> to extend that layer in the stack the full length of the first die <NUM>.

An aperture, hole, or opening <NUM> may be formed into the protective layer <NUM>. A bond pad <NUM> may be disposed in the aperture <NUM>. The bond pad <NUM> may be in contact with the shield layer <NUM> through the aperture <NUM> to electrically couple the shield layer <NUM> to at least one of the signal leads <NUM> through an interconnect 460c. The interconnect 460c may be a wire bond. In some examples, the bond pad <NUM> is a ground pad that is coupled to a ground signal lead <NUM> of the current sensor <NUM>. Thus, the shield layer <NUM> can be coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage).

The second die <NUM> may include a substrate <NUM> having a first surface 410a and a second surface 410b. The substrate <NUM> may be a semiconductor material. A magnetic field sensing circuit <NUM> and associated circuitry may be disposed along the second surface 410b. The magnetic field sensing circuit <NUM> may include an integrated circuit (IC), having at least one magnetic field transducer or sensing element (e.g., a Hall-effect element, magnetoresistance element, giant magnetoresistance element and interface circuitry (not shown)) of a magnetic field sensor provided therein. The substrate <NUM> may be a semiconductor material or an insulating substrate.

The magnetic field sensing element <NUM> may include a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance elements may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element. The magnetic field sensing element <NUM> may be diffused into the second surface 410b or otherwise disposed on or supported by the second surface 410b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

A plurality of interconnects 460a-460b may electrically couple the second surface 410b to at least one signal lead <NUM>. The interconnects 460a-460b may be coupled to the second surface 410b. The interconnects 460a-460b can be configured to couple the magnetic field sensing circuit <NUM> and associated circuitry (i.e. active circuitry) to at least one of the signal leads <NUM>.

The first die <NUM> may operate as an insulation layer and/or a shielding layer for the second die <NUM>. For example, and as illustrated in <FIG>, the first die <NUM> is disposed between the second die <NUM> and the conductor <NUM>. The first die <NUM> can be configured to provide shielding and insulation (e.g. protective layer <NUM>, shield layer <NUM>) for the magnetic field sensing circuit, including a magnetic field sensing element <NUM>, from the current carrying conductor <NUM>. Thus, in an example, the current sensor <NUM> can have a grounded shield layer <NUM> in a die up assembly without using vias, such as those used in the current sensors <NUM>, <NUM>, <NUM> described above with respect to <FIG>.

The length of a layer in current sensor <NUM> (e.g., length of first die <NUM>, second die <NUM>, insulation layer <NUM>) may be selected relative to another layer based on creepage and clearance considerations. For example, to meet a specific standard or need of a particular application of the current sensor <NUM>, the first die <NUM> may be larger (in terms of length or width) than the conductor <NUM> and/or the second die <NUM> to meet a clearance and/or creepage requirement and increase a distance between two conductive parts of the current sensor <NUM>. The length or distance by which the first die <NUM> extends beyond a length of the second die <NUM> and/or conductor <NUM> may vary based on a particular application. For example, a first edge and/or a second edge of the first die <NUM> may extend past a first edge and/or second edge of the conductor <NUM>, the second die <NUM> or both.

Now referring to <FIG>, a current sensor <NUM> having a dual die assembly, also referred herein as a stacked die assembly, is provided. The current sensor <NUM> includes a conductor <NUM>, a first die <NUM> having a first surface proximal to the conductor <NUM> and a second opposing surface distal from the conductor <NUM> and a second die <NUM> having a first surface 510a proximal to the first die <NUM> and a second opposing surface 510b distal from the first die <NUM> and supporting a magnetic field sensing circuit. The first die <NUM> may include a shield layer <NUM> and as will be described in greater detail below, the first die <NUM> may operate as an insulation layer and/or a shielding layer for the second die <NUM>.

The current sensor <NUM> may be similar to current sensor <NUM> described above with respect to <FIG>, as in current sensor <NUM> has a dual die (e.g. first die <NUM>, second die <NUM>) assembly. However, current sensor <NUM> may further include a second insulation layer <NUM> in the first die <NUM>.

The current sensor <NUM> can be provided in the form of an IC having a lead frame. The lead frame may have two portions, a first portion for carrying a primary current to be detected and a second portion for carrying signals to and from the current sensor. The first portion may provide the conductor <NUM> and the second portion may include a plurality of signal leads <NUM>.

The first die may include a first insulation layer <NUM> having a first surface proximal to the second surface of the substrate <NUM> and having a second opposing surface. The first insulation layer <NUM> may be disposed between the shield layer <NUM> and the substrate <NUM>. The first insulation layer <NUM> may include one or more layers of insulation. The one or more layers of the first insulation layer <NUM> may include different materials. Alternatively, each of the multiple first insulation layers <NUM> may include the same materials. The substrate <NUM> may be an insulating substrate and the first insulation layer <NUM> may not be necessary.

The first die <NUM> may include a second insulation layer <NUM> disposed between the conductor <NUM> and the substrate <NUM>. The second insulation layer <NUM> may be applied or coated to a surface of the substrate <NUM>. Alternatively, the second insulation layer <NUM> may be applied or coated to a surface of the conductor <NUM> and the substrate <NUM> may be disposed over a first surface of the second insulation layer <NUM>. Thus, the second insulation layer <NUM> may be disposed over the second surface of the substrate <NUM> or the first surface of the conductor <NUM>.

The protective layer <NUM> may include a polymer dielectric material or benzocyclobutene (BCB). The shield layer <NUM> may be applied to a surface of the protective layer <NUM>. Alternatively, the protective layer <NUM> may be applied or coated over a surface of the shield layer <NUM>. The protective layer <NUM> may include a PECVD oxide, nitride and alumina combination (e.g., aluminum oxide). In one example, protective layer <NUM> may include a PECVD oxide, nitride and alumina combination (e.g., aluminum oxide) in combination with BCB and/or PI (polyimide).

The shield layer <NUM> may be disposed over a first surface of the first insulation layer <NUM>. For example, the shield layer <NUM> may be applied or coated over the first surface of the first insulation layer <NUM>. The shield layer <NUM> may include copper, aluminum or other types of conductive metal materials.

The first insulation layer <NUM> can be disposed over a first surface of the substrate <NUM>. The first insulation layer <NUM> may be applied or coated over the first surface of the substrate <NUM>. Alternatively, the first insulation layer <NUM> may be applied to a surface of the shield layer <NUM> and then disposed on the substrate <NUM>. The first insulation layer <NUM> may include silicon oxide, silicon dioxide or a combination of both. The substrate <NUM> may include a semiconductor material, such as a silicon wafer. Alternatively, the substrate <NUM> may be an insulating substrate and include materials such as Alumina or glass.

The second insulation layer <NUM> may include a polymer dielectric material. For example, the polymer dielectric material may include at least one of BCB, a polyimide material, or a layer of adhesive. The second insulation layer <NUM> may include a flex circuit having a layer of Kapton® and a metalized layer.

The first die <NUM> may include a flex circuit. For example, the flex circuit may include a first layer of Kapton®, a metalized layer disposed over the first layer of Kapton®, a second layer of Kapton® disposed over the metallization layer and a third insulation layer disposed over the second layer of Kapton®.

An aperture, hole, or opening <NUM> may be formed into the protective layer <NUM>. A bond pad <NUM> may be disposed in the aperture <NUM>. The bond pad <NUM> may be in contact with the shield layer <NUM> through the aperture <NUM> to electrically couple the shield layer <NUM> to at least one of the signal leads <NUM> through an interconnect 560c. The interconnect 560c may be a wire bond. In some examples, the bond pad <NUM> is a ground pad that is coupled to a ground signal lead <NUM> of the current sensor <NUM>. Thus, the shield layer <NUM> can be coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage).

The second die <NUM> may include a substrate <NUM> having a first surface 510a and a second surface 510b. The substrate <NUM> may be a semiconductor material or an insulating substrate. A magnetic field sensing element <NUM> and associated circuitry may be disposed along the second surface 510b. The magnetic field sensing element <NUM> may include a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance elements may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element.

The magnetic field sensing element <NUM> may be diffused into the second surface 510b or otherwise disposed on or supported by the second surface 510b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

A plurality of interconnects 560a-560b may electrically couple the second surface 510b to at least one signal lead <NUM>. The interconnects 560a-560b may be coupled to the second surface 510b. Bond pads may be disposed on the second surface <NUM> b to couple to the interconnects 560a-560b. The interconnects 560a-560b can be configured to couple the magnetic field sensing element <NUM> (i.e. active circuitry) to at least one of the signal leads <NUM>.

In the illustrative example of <FIG>, current sensor <NUM> includes the second insulation layer <NUM> in the first die <NUM>. The second insulation layer <NUM> may include one or more layers of insulation. The one or more layers of the second insulation layer <NUM> may include different materials. Alternatively, each of the multiple second insulation layers <NUM> may include the same materials.

The second insulation layer <NUM> may provide a second layer of voltage isolation for the magnetic field sensing element <NUM> from the conductor <NUM>. For example, the first die <NUM> may operate as an insulation layer and/or a shielding layer for the second die <NUM>. The first die <NUM> is disposed between the second die <NUM> and the conductor <NUM>. The first die <NUM> can be configured to provide multiple layers of shielding and/or insulating (e.g. protective layer <NUM>, shield layer <NUM>, first insulation layer <NUM>, second insulation layer <NUM>) for the magnetic field sensing element <NUM> from the current carrying conductor <NUM>. The second insulation layer <NUM> may be referred to as a wafer backside coating.

The first die <NUM> may be larger (e.g. width, length) than the conductor <NUM> and/or the second die <NUM>. The length of a layer in current sensor <NUM> (e.g., length of first die <NUM>, second die <NUM>) may be selected relative to another layer based on creepage and clearance considerations. For example, the first die <NUM> may have at least one edge 570a, 570b that extends beyond an edge 540c, 540d of the conductor <NUM> and/or an edge 580a, 580b of the second die <NUM>. In some examples, both a first edge 570a of the first die <NUM> extends beyond a first edge 540c of the conductor <NUM> and a second edge 570b of the first die <NUM> extends beyond second edge 540b of the conductor <NUM>. A first edge 570a of the first die <NUM> may extend beyond a first edge 580a of the second die <NUM> and a second edge 570b of the first die <NUM> may extend beyond a second edge 580b of the second die <NUM>.

To meet a specific standard or need of a particular application of the current sensor <NUM>, the first die <NUM> may be larger (in terms of length or width) than the conductor <NUM> and/or the second die <NUM> to meet a clearance and/or creepage requirement and increase a distance between two conductive parts of the current sensor <NUM>. In some examples, having the first die <NUM> larger than the conductor <NUM>, the second die <NUM> or both provides further voltage isolation for the magnetic field sensing element <NUM> from the conductor <NUM>.

The second edge 570b may span a gap between the second edge 540b of the conductor <NUM> and at least one signal lead <NUM>. Therefore, the second edge 540b may be in contact with at least one signal lead <NUM>.

Now referring to <FIG>, a current sensor <NUM> having a die up assembly and with a shield layer <NUM> to reduce the effects of electrical, voltage, or electrical transient noise coupled to the active circuitry through parasitic capacitance between the conductor <NUM> and the circuitry. The current sensor <NUM> includes a conductor <NUM>, an insulation layer <NUM> in contact with the conductor <NUM>, a shield layer <NUM> comprising at least one of a metalized tape or a metalized Mylar® spaced from the conductor <NUM> by the insulation layer <NUM> and a semiconductor substrate <NUM> having a first surface 610a disposed proximal to the shield layer <NUM> and a second opposing surface 610b disposed distal from the shield layer <NUM> and supporting a magnetic field sensing element <NUM>.

Current sensor <NUM> may be provided in the form of an integrated circuit having a lead frame. The lead frame may include a first portion for carrying a primary current and a second portion for carrying signals to and from the current sensor <NUM>. The first portion of the lead frame may provide the conductor <NUM> and the second portion may comprise a plurality of signal leads 645a, 645b.

The semiconductor substrate <NUM> may have a first surface 610a disposed proximal to the shield layer <NUM> and a second surface 610b disposed distal from the shield layer <NUM>. A magnetic field sensing element <NUM> and associated circuitry may be disposed on the second surface 610b. Thus, the second surface 610b may support the magnetic field sensing element <NUM> and associated circuitry and the current sensor <NUM> may have a die up assembly. The magnetic field sensing element <NUM> may include at least one of a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance element may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element.

The magnetic field sensing element <NUM> may be diffused into the second surface 610b or otherwise disposed on or supported by the second surface 610b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

The shield layer <NUM> can be disposed between the semiconductor substrate <NUM>, having the magnetic field sensing element <NUM>, and the insulation layer <NUM>. The shield layer <NUM> can be spaced from the conductor <NUM> by the insulation layer <NUM> and therefore, the shield layer <NUM> is disposed between the magnetic field sensing element <NUM> and the current carrying conductor <NUM>. The shield layer <NUM> may be applied to or otherwise coated on the first surface 610a of the substrate <NUM>. For example, the shield layer <NUM> may be plated to the first surface 610a. Alternatively, the shield layer <NUM> may be disposed on the insulation layer <NUM> and the substrate <NUM> may be disposed on the shield layer <NUM>.

The shield layer <NUM> may include at least one of a metalized tape or metalized Mylar®. The shield layer <NUM> may include multiple layers (e.g. two or more layers). For example, an adhesive layer or a nonconductive adhesive layer may be disposed over or otherwise formed over a first surface of shield layer <NUM> such that is it between shield layer <NUM> and semiconductor substrate <NUM>. One or more of the shield layers <NUM> may include different materials. Alternatively, each of the multiple shield layers <NUM> may include the same materials.

The current sensor <NUM> may have a floating shield layer <NUM> (e.g. not grounded). For example, the shield layer <NUM> may not be coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage) or signal leads 645a, 645b.

The insulation layer <NUM> may be applied or coated to a surface of the conductor <NUM>. The substrate <NUM> may be mounted or otherwise disposed on the conductor <NUM>. The substrate <NUM> may be mounted after the shield layer <NUM> has been applied to the first surface 610a and after the insulation layer <NUM> has been applied to the first surface of the conductor <NUM>. Thus, the shield layer <NUM> can be mounted on or otherwise disposed on the insulation layer <NUM> and make contact with the insulation layer <NUM>. The substrate <NUM> may be separated from the conductor <NUM> by at least the shield layer <NUM> and the insulation layer <NUM>.

Now referring to <FIG>, a current sensor <NUM> having a die up assembly and with a shield layer <NUM> to reduce the effects of electrical, voltage, or electrical transient noise coupled to the active circuitry through parasitic capacitance between the conductor <NUM> and the circuitry. The current sensor <NUM> includes a conductor <NUM>, an insulation layer <NUM> in contact with the conductor <NUM>, a shield layer <NUM> comprising at least one of a metalized tape or a metalized Mylar® spaced from the conductor <NUM> by the insulation layer <NUM> and a semiconductor substrate <NUM> having a first surface 710a disposed proximal to the shield layer <NUM> and a second opposing surface 710b disposed distal from the shield layer <NUM> and supporting a magnetic field sensing element <NUM>.

Current sensor <NUM> may be provided in the form of an integrated circuit having a lead frame. The lead frame may include a first portion for carrying a primary current and a second portion for carrying signals to and from the current sensor <NUM>. The first portion of the lead frame may provide the conductor <NUM> and the second portion may comprise a plurality of signal leads 745a, 745b.

The semiconductor substrate <NUM> may have a first surface 710a disposed proximal to the shield layer <NUM> and a second surface 710b disposed distal from the shield layer <NUM>. A magnetic field sensing element <NUM> may be disposed long the second surface 710b. Thus, the second surface 710b may support the magnetic field sensing element <NUM> and associated circuitry (i.e. magnetic field sensing circuit) and the current sensor <NUM> has a die up assembly.

The magnetic field sensing element <NUM> may include at least one of a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance element may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element. The magnetic field sensing element <NUM> may be diffused into the second surface 710b or otherwise disposed on or supported by the second surface 710b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

As illustrated in <FIG>, the shield layer <NUM> is disposed between the semiconductor substrate <NUM>, having the magnetic field sensing element <NUM>, and the insulation layer <NUM>. This may be referred to as a backside die shield, as the first surface 710a distal from the magnetic field sensing element <NUM> is coated with the shield layer <NUM>. The shield layer <NUM> may be applied to or otherwise coated on the first surface 710a of the substrate <NUM>. For example, the shield layer <NUM> may be plated to the first surface 710a. Alternatively, the shield layer <NUM> may be disposed on the insulation layer <NUM> and the substrate <NUM> may be disposed on the shield layer <NUM>.

The shield layer <NUM> may include at least one of a metalized tape or metalized Mylar®. The shield layer <NUM> may include multiple layers (e.g. two or more layers). For example, an adhesive layer or a nonconductive adhesive layer may be disposed over or otherwise formed over a first surface of shield layer <NUM> such that is it between shield layer <NUM> and semiconductor substrate710. One or more of the shield layers <NUM> may include different materials. Alternatively, each of the multiple shield layers <NUM> may include the same materials.

The shield layer <NUM> can be spaced from the conductor <NUM> by the insulation layer <NUM> and therefore, the shield layer <NUM> can be disposed between the magnetic field sensing element <NUM> and the current carrying conductor <NUM>. The insulation layer <NUM> may be applied or coated to a surface of the conductor <NUM>. The substrate <NUM> may be mounted or otherwise disposed on the conductor <NUM>. The substrate <NUM> may be mounted after the shield layer <NUM> has been applied to the first surface 710a and after the insulation layer <NUM> has been applied to the first surface of the conductor <NUM>. Thus, the shield layer <NUM> can be mounted on or otherwise disposed on the insulation layer <NUM> and make contact with the insulation layer <NUM>.

Current sensor <NUM> may be different from current sensor <NUM> described above with respect to <FIG>, in that the shield layer <NUM> is coupled to at least one signal lead 745a. For example, an interconnect <NUM> may couple the shield layer <NUM> to at least one signal lead 745a. A first bond pad 726a (or connection area as it may not be a patterned pad) may be disposed on the first surface of the shield layer <NUM> and a second bond pad 726b may be disposed on a first surface of the signal lead 745a. The interconnect <NUM> may be coupled to both the first bond pad 726a and the second bond pad 726b. The interconnect <NUM> may include a wire bond. The shield layer <NUM> may be coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage) through the interconnect <NUM>. Thus, in operation, the shield layer <NUM>, which is electrically coupled to a reference potential, serves to tie one place of undesirable parasitic capacitance between the conductor <NUM> and substrate <NUM> to the reference potential (e.g., ground).

Now referring to <FIG>, a current sensor <NUM> having a die up assembly and with a shield layer <NUM> to reduce the effects of electrical, voltage, or electrical transient noise coupled to the active circuitry through parasitic capacitance between the conductor <NUM> and the circuitry. The current sensor <NUM> includes a conductor <NUM>, an insulation layer <NUM> in contact with the conductor <NUM>, a shield layer <NUM> comprising at least one of a metalized tape or a metalized Mylar® spaced from the conductor <NUM> by the insulation layer <NUM> and a semiconductor substrate <NUM> having a first surface 810a disposed proximal to the shield layer <NUM> and a second opposing surface 810b disposed distal from the shield layer <NUM> and supporting a magnetic field sensing element <NUM>.

Current sensor <NUM> may be provided in the form of an integrated circuit having a lead frame. The lead frame may include a first portion for carrying a primary current and a second portion for carrying signals to and from the current sensor <NUM>. The first portion of the lead frame may provide the conductor <NUM> and the second portion may comprise a plurality of signal leads 845a, 845b.

The semiconductor substrate <NUM> may have a first surface 810a disposed proximal to the shield layer <NUM> and a second surface 810b disposed distal from the shield layer <NUM>. A magnetic field sensing element <NUM> may be disposed long the second surface 810b. Thus, the second surface 810b may support the magnetic field sensing element <NUM> and associated circuitry (i.e. magnetic field sensing circuit) and the current sensor <NUM> has a die up assembly. The magnetic field sensing element <NUM> may include at least one of a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance element may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element.

The magnetic field sensing element <NUM> may be diffused into the second surface 810b or otherwise disposed on or supported by the second surface 810b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

As illustrated in <FIG>, the shield layer <NUM> is disposed between the semiconductor substrate <NUM>, having the magnetic field sensing element <NUM>, and the insulation layer <NUM>. This may be referred to as a backside die shield, as the first surface 810a distal from the magnetic field sensing element <NUM> is coated with the shield layer <NUM>. The shield layer <NUM> may be applied to or otherwise coated on the first surface 810a of the substrate <NUM>. For example, the shield layer <NUM> may be plated to the first surface 810a. Alternatively, the shield layer <NUM> may be disposed on the insulation layer <NUM> and the substrate <NUM> may be disposed on the shield layer <NUM>.

The shield layer <NUM> may include at least one of a metalized tape or metalized Mylar®. The shield layer <NUM> may include multiple layers (e.g. two or more layers). One or more of the shield layers <NUM> may include different materials. Alternatively, each of the multiple shield layers <NUM> may include the same materials.

The shield layer <NUM> can be spaced from the conductor <NUM> by the insulation layer <NUM> and therefore, the shield layer <NUM> can be disposed between the magnetic field sensing element <NUM> and the current carrying conductor <NUM>. In operation, the shield layer <NUM>, which is electrically coupled to a reference potential, serves to tie one place of undesirable parasitic capacitance between the conductor <NUM> and substrate <NUM> to the reference potential (e.g., ground).

The insulation layer <NUM> may be applied or coated to a surface of the conductor <NUM>. In some examples, such as during a manufacturing process of current sensor <NUM>, the substrate <NUM> may be mounted or otherwise disposed on the conductor <NUM>. The substrate <NUM> may be mounted after the shield layer <NUM> has been applied to the first surface 810a and after the insulation layer <NUM> has been applied to the first surface of the conductor <NUM>. Thus, the shield layer <NUM> can be mounted on or otherwise disposed on the insulation layer <NUM> and make contact with the insulation layer <NUM>.

Current sensor <NUM> may be different from current sensor <NUM> described above with respect to <FIG> and current sensor <NUM> described above with respect to <FIG>, in that a via <NUM> is formed within the semiconductor substrate <NUM>. The via <NUM> may be a through-silicon via and can extend through the semiconductor substrate <NUM>, from the first surface 810a to the second surface 810b. The via <NUM> may couple the shield layer <NUM> to the second surface 810b of the semiconductor substrate <NUM>. A conductive adhesive, a conductive solder or like material may be used to couple the shield layer <NUM> to the second surface 810b of the semiconductor substrate <NUM>.

An interconnect <NUM> may couple the via <NUM> to at least one signal lead 845a. For example, a first bond pad 826a can be disposed on the second surface 810b and a second bond pad 826b can be disposed on a first surface of the signal lead <NUM>. The interconnect <NUM> can be coupled to both the first bond pad 826a and the second bond pad 826b to couple the via <NUM> to the signal lead 845a.

The via <NUM> can be coupled to a reference potential (e.g., a reference voltage, a supply voltage, a DC voltage, ground voltage) through the interconnect <NUM>. The shield layer <NUM> can be coupled to at least one signal lead 845a through the via <NUM> and the interconnect <NUM>.

Now referring to <FIG>, a current sensor <NUM> having a die up assembly and with a shield layer <NUM> to reduce the effects of electrical, voltage, or electrical transient noise coupled to the active circuitry through parasitic capacitance between the conductor <NUM> and the circuitry. The current sensor <NUM> includes a conductor <NUM>, an insulation layer <NUM> in contact with the conductor <NUM>, a shield layer <NUM> comprising at least one of a metalized tape or a metalized Mylar® spaced from the conductor <NUM> by the insulation layer <NUM> and a semiconductor substrate <NUM> having a first surface 910a disposed proximal to the shield layer <NUM> and a second opposing surface 910b disposed distal from the shield layer <NUM> and supporting a magnetic field sensing element <NUM>.

The current sensor <NUM> may include a conductive epoxy layer <NUM> disposed over a first surface of the shield layer <NUM>. Thus, the conductive epoxy layer <NUM> may be disposed between the shield layer <NUM> and the substrate <NUM>. The conductive epoxy layer <NUM> may be formed along at least one side or edge surface of the substrate <NUM>.

Current sensor <NUM> may be provided in the form of an integrated circuit having a lead frame. The lead frame may include a first portion for carrying a primary current and a second portion for carrying signals to and from the current sensor <NUM>. The first portion of the lead frame may provide the conductor <NUM> and the second portion may comprise a plurality of signal leads 945a, 945b.

The semiconductor substrate <NUM> may have a first surface 910a disposed proximal to the shield layer <NUM> and a second surface 910b disposed distal from the shield layer <NUM>. A magnetic field sensing element <NUM> may be disposed long the second surface 910b. Thus, the second surface 910b may support the magnetic field sensing element <NUM> and associated circuitry (i.e. magnetic field sensing circuit) and the current sensor <NUM> has a die up assembly. The magnetic field sensing element <NUM> may include at least one of a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance element may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element.

The magnetic field sensing element <NUM> may be diffused into the second surface 910b or otherwise disposed on or supported by the second surface 910b. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

The shield layer <NUM> is disposed between the conductive epoxy layer <NUM> and the insulation layer <NUM>. The shield layer <NUM> may be applied to or otherwise coated on a first surface of the conductive epoxy layer <NUM>. Alternatively, the shield layer <NUM> may be disposed on the insulation layer <NUM> and the conductive epoxy layer <NUM> may be disposed on the shield layer <NUM>.

The shield layer <NUM> can be spaced from the conductor <NUM> by the insulation layer <NUM> and can be spaced from the semiconductor substrate <NUM> (having the magnetic field sensing element <NUM>) by the conductive epoxy layer <NUM>, thus the shield layer <NUM> can be disposed between the magnetic field sensing element <NUM> and the current carrying conductor <NUM>. In operation, the shield layer <NUM>, which is electrically coupled to a reference potential, serves to tie one place of undesirable parasitic capacitance between the conductor <NUM> and substrate <NUM> to the reference potential (e.g., ground).

The insulation layer <NUM> may be applied or coated to a surface of the conductor <NUM>. In some examples, such as during a manufacturing process of current sensor <NUM>, the substrate <NUM> may be mounted or otherwise disposed on the conductor <NUM>. The substrate <NUM> may be mounted after the shield layer <NUM> has been applied to the first surface 910a and after the insulation layer <NUM> has been applied to the first surface of the conductor <NUM>. Thus, the shield layer <NUM> can be mounted on or otherwise disposed on the insulation layer <NUM> and make contact with the insulation layer <NUM>.

An interconnect <NUM> may electrically couple the second surface 910b to at least one signal lead 945a. For example, a first bond pad 926a can be disposed on the second surface 910b and a second bond pad 926b can be disposed on a first surface of the signal lead <NUM>. The interconnect <NUM> can be coupled to both the first bond pad 926a and the second bond pad 926b to couple the second surface 910b to the signal lead 945a.

Current sensor <NUM> may be different from current sensor <NUM> described above with respect to <FIG>, in that it includes the conductive epoxy layer <NUM> and no via. The conductive epoxy layer <NUM> may be formed on one or more surfaces of the semiconductor substrate <NUM>. For example, in the illustrative arrangement of <FIG>, the conductive epoxy layer <NUM> is formed a long the first surface 910a and one side surface 910d. Alternatively, the conductive epoxy layer <NUM> may be formed on only one surface or alternatively on two or more surfaces (including side surfaces) of the semiconductor substrate <NUM>.

The conductive epoxy layer <NUM> may include at least one of a conductive die attach epoxy or a metallized tape. The interconnect <NUM> may couple the conductive epoxy layer <NUM> to at least one signal lead 945a.

Now referring to <FIG>, a current sensor <NUM> includes a first die <NUM> having a first surface 1075a and a second opposing surface 1075b supporting a conductor <NUM> in the form of a coil and a second die <NUM> having a first surface on which a shield layer <NUM> is formed and a second opposing surface. The shield layer <NUM> may include a slit <NUM> that may be the same as or similar to the slit shown in <FIG>. The shield layer <NUM> may be spaced from the second surface 1075b of the first die <NUM> by an airgap <NUM> and the current sensor may include a magnetic field sensing element adjacent to the conductor <NUM> and configured as a flip chip.

As illustrated in <FIG>, the current sensor <NUM> includes a first die <NUM> and a second die <NUM>. Thus, the current sensor <NUM> may have a dual die or stacked die assembly. In some examples, and as will be described in greater detail below, the first die <NUM> may be an interposer having a coil <NUM> and the second die may be an IC having a magnetic field sensing element <NUM>.

The first die <NUM> may be spaced apart from the second die <NUM> by an airgap <NUM> in a flip chip configuration. A plurality of solder balls or other electrical interconnect structure 1026b-1026c may be disposed between respective bond pads 1026a, 1026d on the first die <NUM> and on the second die <NUM>. The plurality of solder balls 1026b-1026c may be microbumps. The solder balls 1026b-1026c may be disposed along the second surface of the first die <NUM>. The space created by airgap <NUM> may be filled with an underfill material or an epoxy mold compound material during packaging.

The first die <NUM> includes a conductor <NUM> having the coil <NUM>. The coil <NUM> may have thickness that ranges from about <NUM> to about <NUM>. The conductor has a first surface 1075a and a second surface 1075b. In the illustrative example of <FIG>, the coil <NUM> is disposed proximal to the second surface 1075b. A current path <NUM> may be formed within the conductor <NUM> to couple the coil <NUM> to at least two bond pads 1026a, 1026d. For example, in some arrangements, the coil <NUM> may be coupled to bond pads 1026a, 1026d.

The first die <NUM> may include a silicon interposer. For example, the conductor <NUM> may include a copper redistribution layer (Cu RDL) and the coil <NUM> can be disposed within the copper redistribution layer. The coil <NUM> may include a single copper or conductive trace.

A shield layer <NUM> may be disposed along one surface (here the first surface 1075a) of the conductor <NUM>. The shield layer <NUM> may be applied or otherwise coated on the first surface 1075a. The shield layer <NUM> may be provided as a back side die shield (or back side metallization) for the first die <NUM>. The shield layer <NUM> may include copper, aluminum or other conductive metal material.

The second die <NUM> includes a first shield layer <NUM>, a protective layer <NUM> disposed along a second surface of the first shield layer <NUM>, a first semiconductor substrate <NUM> disposed along a second surface of the protective layer <NUM>, a second semiconductor substrate <NUM> disposed along a second surface of the first semiconductor substrate <NUM> and a second shield layer <NUM> disposed along a second surface of the second semiconductor substrate <NUM>. In some examples, contacts to the different layers of second die <NUM> can be made through additional solder balls 1026a-1026c and/or wire bonds (not shown) to make an electrical connection to the magnetic field sensor and thus, to magnetic field sensing element <NUM>.

The protective layer <NUM> may be applied or coated on the second surface of the first shield layer <NUM>. The first semiconductor substrate <NUM> may be applied or disposed on a surface of the protective layer <NUM>. Alternatively, the protective layer <NUM> may be applied or coated on a surface of the first semiconductor substrate <NUM> and the first shield layer <NUM> may be applied or coated on a surface of the protective layer <NUM>.

The second semiconductor substrate <NUM> may be applied to a surface of the first semiconductor substrate <NUM>. The second shield layer <NUM> may be applied to or coated on a surface of the second semiconductor substrate <NUM>.

In some examples, the first semiconductor substrate <NUM> includes a metallization layer. For example, the first semiconductor substrate <NUM> may include a back end of line (BEOL) metallization layer. The second semiconductor substrate <NUM> may include a metallization layer. For example, the second semiconductor substrate <NUM> may include a front end of line (FEOL) metallization layer. In one example, the second semiconductor substrate <NUM> may include an FEOL complementary metal-oxide semiconductor (CMOS) wafer.

The first and second shield layers <NUM>, <NUM> may include copper, aluminum or other conductive metal material. The second shield layer <NUM> may be disposed along the second surface of the second semiconductor substrate <NUM> as a back side shield layer or back side metallization.

The protective layer <NUM> includes a magnetic field sensing element <NUM>. The magnetic field sensing element <NUM> may include a magnetic field sensing circuit and may include at least one of a Hall-effect element or a magnetoresistance element. For example, the magnetoresistance element may include at least one of Indium Antimonide (InSb), a GMR element, an AMR element, a TMR element or a MTJ element. The magnetic field sensing element <NUM> may be positioned such that is it adjacent to or aligned with the coil <NUM> in the first die <NUM>.

The magnetic field sensing element <NUM> may be diffused into a surface or otherwise disposed on or supported by a surface of the protective layer <NUM>. While only one magnetic field sensing element <NUM> is shown, it should be appreciated that more than one magnetic field sensing element <NUM> may be used in current sensor <NUM>.

The first shield layer <NUM> can be disposed between the protective layer <NUM> (having the magnetic field sensing element <NUM>) and the conductor <NUM>. The first shield layer <NUM> may include a slit <NUM> that may be a slot, cut or a cross shaped opening formed in the first shield layer <NUM> and that may take the various forms and provide the advantages discussed above in connection with <FIG>.

Shield layers (e.g. first shield layer <NUM>, second shield layer <NUM> and third shield layer <NUM>) may serve to electrically tie one plate of undesirable parasitic capacitance between the conductor <NUM> and the first and/or second substrate <NUM>, <NUM> to a reference potential. The shield layers (e.g. first shield layer <NUM>, second shield layer <NUM> and third shield layer <NUM>) can be disposed along one side of the first die <NUM> and one side of the second die <NUM>. Thus, in some examples, the current sensor <NUM> may have a shield layer on both ends, the second shield layer <NUM> disposed along the second surface of the second die <NUM> and the third shield layer <NUM> disposed along the first surface of the first die <NUM>. This may be referred to as back side die shielding or back side metallization with back side shielding applied to both the first die <NUM> (e.g. interposer) and the second die <NUM> (e.g. MOS IC).

Claim 1:
A current sensor (<NUM>,<NUM>,<NUM>) comprising:
a conductor (<NUM>,<NUM>,<NUM>);
an insulation layer (<NUM>,<NUM>,<NUM>) in contact with the conductor (<NUM>,<NUM>,<NUM>);
a shield layer (<NUM>,<NUM>,<NUM>) spaced from the conductor (<NUM>,<NUM>,<NUM>) by the insulation layer (<NUM>,<NUM>,<NUM>) and coupled to a reference potential;
a semiconductor substrate (<NUM>,<NUM>,<NUM>) having a first surface (110a,210a,310a) in contact with the shield layer (<NUM>,<NUM>,<NUM>) and a second opposing surface (110b,210b,310b) disposed distal from the shield layer (<NUM>,<NUM>,<NUM>), wherein an edge of the insulation layer (<NUM>,<NUM>,<NUM>) extends beyond an edge of the conductor (<NUM>,<NUM>,<NUM>), the shield layer (<NUM>,<NUM>,<NUM>) and the semiconductor substrate (<NUM>,<NUM>,<NUM>);
a magnetic field sensing circuit comprising a magnetic field sensing element (<NUM>,<NUM>,<NUM>) supported by the first or second surface of the substrate (<NUM>,<NUM>,<NUM>), wherein the reference potential to which the shield layer (<NUM>,<NUM>,<NUM>) is coupled is a reference potential of the magnetic field sensing circuit; and
a via (<NUM>,<NUM>,<NUM>) extending through the semiconductor substrate (<NUM>,<NUM>,<NUM>) to couple the shield layer (<NUM>,<NUM>,<NUM>) to the second surface (110b,210b,310b) of the semiconductor substrate (<NUM>,<NUM>,<NUM>), wherein the shield layer (<NUM>,<NUM>,<NUM>) is coupled to the reference potential through the via (<NUM>,<NUM>,<NUM>).