US20170234942A1 - Layouts for interlevel crack prevention in fluxgate technology manufacturing - Google Patents
Layouts for interlevel crack prevention in fluxgate technology manufacturing Download PDFInfo
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- US20170234942A1 US20170234942A1 US15/042,119 US201615042119A US2017234942A1 US 20170234942 A1 US20170234942 A1 US 20170234942A1 US 201615042119 A US201615042119 A US 201615042119A US 2017234942 A1 US2017234942 A1 US 2017234942A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R33/00—Arrangements or instruments for measuring magnetic variables
- G01R33/02—Measuring direction or magnitude of magnetic fields or magnetic flux
- G01R33/04—Measuring direction or magnitude of magnetic fields or magnetic flux using the flux-gate principle
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/01—Manufacture or treatment
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/80—Constructional details
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/80—Constructional details
- H10N50/85—Magnetic active materials
Definitions
- This disclosure relates to the field of microelectronic devices. More particularly, this disclosure relates to fluxgate magnetometer sensors in microelectronic devices.
- Fluxgate magnetometer sensors in microelectronic devices have thin film magnetic material in the fluxgate cores embedded in dielectric material.
- the fluxgate cores are typically more than a micron thick to provide a desired sensitivity for the sensor.
- An integrated fluxgate device containing a fluxgate magnetometer sensor has a fluxgate core of a thin film magnetic material.
- the fluxgate magnetometer sensor has a crack-resistant structure at an end of the fluxgate core.
- the crack-resistant structure includes at least one of a laterally rounded contour of the fluxgate core at the end having corner radii of at least 2 microns, a lower metal end structure in the lower dielectric layer extending under the end of the fluxgate core, or an upper metal end structure in the upper dielectric layer extending over the end of the fluxgate core.
- FIG. 1 is an exploded view of an example integrated fluxgate device containing a fluxgate magnetometer sensor.
- FIG. 2A through FIG. 2G depict an example method of forming the structure of FIG. 1 .
- FIG. 3 is an exploded view of another example integrated fluxgate device containing a fluxgate magnetometer sensor.
- FIG. 4A through FIG. 4G depict an example method of forming the structure of FIG. 3 .
- An integrated fluxgate device containing a fluxgate magnetometer sensor has a fluxgate core of a thin film magnetic material.
- the fluxgate magnetometer sensor has a crack-resistant structure at an end of the fluxgate core.
- the crack-resistant structure includes at least one of a laterally rounded contour of the fluxgate core at the end having corner radii of at least 2 microns, a lower metal end structure extending under the end of the fluxgate core, or an upper metal end structure in the upper dielectric layer extending over the end of the fluxgate core. Tests performed in pursuit of the instant disclosure have shown corner radii of at least 2 microns to be effective in reducing instances of cracks in dielectric material surrounding the fluxgate core.
- the lower metal end structure and the upper metal end structure may include winding segments of windings around the fluxgate core.
- the lower metal end structure and the upper metal end structure may be electrically coupled to the windings.
- the lower metal end structure and the upper metal end structure may be electrically isolated from the windings.
- lateral and laterally are understood to refer to a direction parallel to a plane of a top surface of the integrated fluxgate device
- vertical and “vertically” are understood to refer to a direction perpendicular to the plane of the top surface of the integrated fluxgate device
- FIG. 1 is an exploded view of an example integrated fluxgate device containing a fluxgate magnetometer sensor.
- the integrated fluxgate device 100 is formed on a substrate 102 .
- the substrate 102 may include a semiconductor material such as silicon.
- a top surface 104 of the substrate 102 includes dielectric material such as silicon dioxide or silicon nitride.
- the dielectric material may be, for example, an inter-level dielectric (ILD) of an interconnect region of the integrated fluxgate device 100 . Interconnects such as vias may be exposed at the top surface 104 .
- the integrated fluxgate device 100 may include electronic circuits with active components such as transistors which are part of the fluxgate magnetometer sensor 106 , referred to herein as the fluxgate sensor 106 .
- the fluxgate sensor 106 includes a fluxgate core 108 of thin film magnetic material.
- the fluxgate core 108 may be, for example, 1 micron to 3 microns thick.
- a width 110 of the fluxgate core 108 may be, for example, 10 microns to 500 microns.
- Increasing the thickness and the width 110 of the fluxgate core 108 may desirably improve the sensitivity of the fluxgate sensor 106 , but may undesirably increase a size and cost of the integrated fluxgate device 100 .
- the thickness and the width 110 may be selected to provide a desired balance between sensitivity and cost.
- the fluxgate sensor 106 includes lower winding segments 112 of windings 114 around the fluxgate core 108 .
- the lower winding segments 112 include metal, and may be part of an interconnect level of the integrated fluxgate device 100 .
- the lower winding segments 112 are disposed under the fluxgate core 108 .
- the fluxgate sensor 106 further includes upper winding segments 116 of the windings 114 .
- the upper winding segments 116 also include metal, and may be part of another interconnect level of the integrated fluxgate device 100 .
- the upper winding segments 116 are disposed over the fluxgate core 108 .
- the upper winding segments 116 may be electrically coupled to the lower winding segments 112 through vias 118 of the windings 114 .
- the vias 118 include metal and may be part of a via level of the integrated fluxgate device 100 .
- the windings 114 including the lower winding segments 112 , the upper winding segments 116 and the vias 118 , are electrically isolated from the fluxgate core 108 by layers of dielectric material, not shown in FIG. 1 in order to more clearly depict the spatial relationship between the fluxgate core 108 , the lower winding segments 112 , the upper winding segments 116 and the vias 118 .
- the fluxgate sensor 106 has a crack-resistant structure 120 at an end 122 of the fluxgate core 108 .
- the crack-resistant structure 120 includes a laterally rounded contour 124 of the fluxgate core 108 having corner radii 126 of at least 2 microns.
- the corner radii 126 are approximately equal to half the width 110 of the fluxgate core 108 at the end 122 , so that the fluxgate core 108 has a semicircular shape at the end 122 .
- the crack-resistant structure 120 includes a lower metal end structure 128 which extends under the end 122 of the fluxgate core 108 .
- the lower metal end structure 128 includes at least one of the lower winding segments 112 which extend under the end 122 of the fluxgate core 108 .
- the crack-resistant structure 120 includes an upper metal end structure 130 which extends over the end 122 of the fluxgate core 108 .
- the upper metal end structure 130 includes at least one of the upper winding segments 116 which extend over the end 122 of the fluxgate core 108 .
- Forming the lower metal end structure 128 and the upper metal end structure 130 of the crack-resistant structure 120 of the lower winding segments 112 and the upper winding segments 116 , respectively, may advantageously improve a sensitivity of the fluxgate sensor 106 .
- Forming the fluxgate core 108 with corner radii 126 approximately equal to half the width 110 of the fluxgate core 108 may advantageously provide increased crack resistance compared to smaller corner radii.
- Each end 122 of the fluxgate core 108 may have a version of the crack resistant structure 120 .
- the crack-resistant structure 120 at a first end 122 may be different from the crack-resistant structure 120 at a second end 122 .
- the fluxgate sensor 106 may contain more than one fluxgate core 108 .
- the fluxgate sensor 106 may be a differential sensor with two fluxgate cores 108 .
- Each end 122 of each fluxgate core 108 may have a version of the crack resistant structure 120 .
- the integrated fluxgate device 100 may include more than one fluxgate sensor 106 , for example to measure magnetic field components along perpendicular axes.
- the crack-resistant structure 120 may be formed at each end 122 of each fluxgate core 108 in the integrated fluxgate device 100 .
- FIG. 2A through FIG. 2G depict an example method of forming the structure of FIG. 1 .
- the substrate 102 of the integrated fluxgate device 100 may be, for example, part of a semiconductor wafer such as a silicon wafer, or may be part of a dielectric substrate such as ceramic or sapphire, containing additional integrated fluxgate devices.
- a first intra-metal dielectric (IMD) layer 132 is formed over the top surface 104 of the substrate 102 .
- the first IMD layer 132 may be, for example, 2 microns to 4 microns thick, and may include a main layer of silicon dioxide, and optionally an etch stop layer of silicon nitride, silicon carbide nitride or silicon carbide, and optionally a cap layer of silicon nitride or silicon carbide nitride.
- Silicon dioxide in the first IMD layer 132 may be formed by a plasma enhanced chemical vapor deposition (PECVD) process using tetraethyl orthosilicate (TEOS).
- TEOS tetraethyl orthosilicate
- Silicon nitride in the first IMD layer 132 may be formed by a PECVD process using bis(tertiary-butyl-amino) silane (BTBAS).
- Trenches for the lower winding segments 112 are formed through the first IMD layer 132 using reactive ion etch (RIE) processes, for a damascene process of forming the lower winding segments 112 .
- the trenches may expose tops of vias at the top surface 104 of the substrate 102 .
- a metal liner of tantalum and/or tantalum nitride is formed over the first IMD layer 132 , extending into the trenches to provide a barrier for the lower winding segments 112 .
- a seed layer of copper is formed on the metal liner by a sputter process, and additional copper is formed on the seed layer by electroplating, filling the trenches with copper.
- the lower winding segments 112 extend past the area for the fluxgate core 108 of FIG. 1 , outlined in FIG. 2A by a dashed border. Instances of the lower winding segments 112 extending under an end of the fluxgate core 108 are part of the lower metal end structure 128 of the crack-resistant structure 120 . Forming the lower metal end structure 128 concurrently with the lower winding segments 112 may advantageously reduce a fabrication cost of the integrated fluxgate device 100 .
- a lower ILD layer 134 is formed over the first IMD layer 132 and over the lower winding segments 112 of FIG. 2A .
- the lower ILD layer 134 may be, for example, 0.5 microns to 1 micron thick, and may include a main layer of silicon dioxide and optionally an etch stop layer.
- the lower ILD layer 134 includes a cap layer of silicon nitride to provide a lower barrier for the fluxgate core 108 of FIG. 1 .
- the lower ILD layer 134 may be formed by PECVD processes, as described in reference to FIG. 2A .
- a layer of magnetic material 136 for the fluxgate core 108 of FIG. 1 is formed over the lower ILD layer 134 .
- the layer of magnetic material 136 may include a stack of alternating sub-layers of iron nickel and aluminum nitride.
- the layer of magnetic material 136 may be, for example, 1 micron to 2 microns thick, to provide a desired sensitivity for the fluxgate sensor 106 .
- An etch mask 138 is formed over the layer of magnetic material 136 to cover the area for the fluxgate core 108 .
- the etch mask 138 may include photoresist formed by a photolithographic process, and may optionally include a layer of anti-reflection material such as a bottom anti-reflection coat (BARC).
- BARC bottom anti-reflection coat
- the etch mask 138 has rounded corners with radii greater than 2 microns.
- an etch process removes the magnetic material from the layer of magnetic material 136 of FIG. 2B in the area exposed by the etch mask 138 .
- the magnetic material remaining under the etch mask 138 forms the fluxgate core 108 .
- the etch process may be, for example, a wet etch process which is selective to the cap layer of silicon nitride at a top of the lower ILD layer 134 .
- the etch mask 138 of FIG. 2C is removed, leaving the fluxgate core 108 in place over the lower ILD layer 134 .
- the etch mask 138 may be removed, for example, using an ash process.
- an upper ILD layer 140 is formed over the lower ILD layer 134 and over the fluxgate core 108 .
- the upper ILD layer 140 includes a layer of silicon nitride to provide an upper barrier over the fluxgate core 108 .
- the upper ILD layer 140 further includes a main layer of silicon dioxide over the layer of silicon nitride, 2 microns to 4 microns thick.
- the main layer of silicon dioxide is planarized, for example by an oxide CMP process, to provide a suitable surface for subsequently forming the upper winding segments 116 of FIG. 1 by a damascene process.
- the upper ILD layer 140 includes a cap layer of silicon nitride over the main layer of silicon dioxide.
- the upper ILD layer 140 may be formed by PECVD processes, as described in reference to FIG. 2A .
- the vias 118 are formed through the upper ILD layer 140 and through the lower ILD layer 134 to make electrical connections to the lower winding segments 112 of FIG. 2A .
- the vias 118 may be formed by a copper damascene process as described in reference to FIG. 2A .
- the vias 118 may be formed by a tungsten damascene process, with a metal liner of titanium and titanium nitride, and fill layer of tungsten formed by a metal organic chemical vapor deposition (MOCVD) process using tungsten hexafluoride reduced by silane and hydrogen.
- MOCVD metal organic chemical vapor deposition
- a second IMD layer 142 is formed over the upper ILD layer 140 .
- the second IMD layer 142 may have a similar thickness, structure and composition to the first IMD layer 132 , and may be formed by similar processes, as described in reference to FIG. 2A .
- Trenches for the upper winding segments 116 are formed through the second IMD layer 142 using RIE processes.
- the trenches for the upper winding segments 116 expose tops of the vias 118 of FIG. 2F .
- the upper winding segments 116 are formed in the trenches by a copper damascene process, as described in reference to FIG. 2A .
- the upper winding segments 116 extend past the area for the fluxgate core 108 of FIG. 1 , outlined in FIG.
- Instances of the upper winding segments 116 extending over an end of the fluxgate core 108 are part of the upper metal end structure 130 of the crack-resistant structure 120 .
- Forming the upper metal end structure 130 concurrently with the upper winding segments 116 may advantageously reduce the fabrication cost of the integrated fluxgate device 100 .
- Forming the lower metal end structure 128 of FIG. 1 and the upper metal end structure 130 of copper may advantageously improve the crack resistance of the crack-resistant structure 120 , due to the high shear stress limit of copper compared to other commonly used interconnect metals.
- a protective overcoat may be formed over the fluxgate sensor 106 .
- Bond pads may be formed in the protective overcoat to provide electrical connections to components in the integrated fluxgate device 100 .
- FIG. 3 is an exploded view of another example integrated fluxgate device containing a fluxgate magnetometer sensor.
- the integrated fluxgate device 300 is formed on a substrate 302 .
- the substrate 302 may include a semiconductor material such as silicon.
- a top surface 304 of the substrate 302 includes dielectric material, possibly a top layer of an ILD layer of the integrated fluxgate device 300 . Vias may be exposed at the top surface 304 .
- the integrated fluxgate device 300 may include electronic circuits which are part of the fluxgate magnetometer sensor 306 , referred to herein as the fluxgate sensor 306 .
- the fluxgate sensor 306 includes a fluxgate core 308 of thin film magnetic material.
- the fluxgate core 308 may have a thickness of 1 micron to 3 microns thick, and a width 310 of 10 microns to 500 microns. The thickness and the width 310 may be selected to provide a desired balance between sensitivity and cost, as described in reference to FIG. 1 .
- the fluxgate sensor 306 includes lower winding segments 312 of windings 314 around the fluxgate core 308 .
- the lower winding segments 312 include metal.
- the lower winding segments 312 are disposed under the fluxgate core 308 . In the instant example, the lower winding segments 312 do not extend to an end 322 of the fluxgate core 308 .
- the fluxgate sensor 306 further includes upper winding segments 316 of the windings 314 .
- the upper winding segments 316 also include metal.
- the upper winding segments 316 are disposed over the fluxgate core 308 . In the instant example, the upper winding segments 316 do not extend to the end 322 of the fluxgate core 308 .
- the upper winding segments 316 may be electrically coupled to the lower winding segments 312 through vias 318 of the windings 314 .
- the vias 318 include metal.
- the windings 314 including the lower winding segments 312 , the upper winding segments 316 and the vias 318 , are electrically isolated from the fluxgate core 308 by layers of dielectric material, not shown in FIG. 3 in order to more clearly depict the spatial relationship between the fluxgate core 308 and the windings 314 .
- the fluxgate sensor 306 has a crack-resistant structure 320 at an end 322 of the fluxgate core 308 .
- the crack-resistant structure 320 includes a laterally rounded contour 324 of the fluxgate core 308 having corner radii 326 of at least 2 microns.
- the corner radii 326 are less than half the width 310 of the fluxgate core 308 at the end 322 , which may advantageously reduce an area of the fluxgate core 308 , hence reducing an area of the integrated fluxgate device 300 and so possibly further reducing a fabrication cost of the integrated fluxgate device 300 .
- the crack-resistant structure 320 includes a lower metal end structure 328 which extends under the end 322 of the fluxgate core 308 .
- the lower metal end structure 328 is separate from the lower winding segments 312 .
- the lower metal end structure 328 may be a single metal element, possibly with slots, as depicted in FIG. 3 .
- the metal in the lower metal end structure 328 occupies at least 50 percent of an area directly under the end 322 of the fluxgate core 308 , starting at the lower winding segments 312 , to provide effective crack resistance.
- the lower metal end structure 328 may be in an interconnect level containing the lower winding segments 312 , possibly reducing the fabrication cost.
- the crack-resistant structure 320 includes an upper metal end structure 330 which extends over the end 322 of the fluxgate core 308 .
- the upper metal end structure 330 is separate from the upper winding segments 316 .
- the upper metal end structure 330 may be a single metal element, possibly with slots, as depicted in FIG. 3 .
- the metal in the upper metal end structure 330 occupies at least 50 percent of an area directly over the end 322 of the fluxgate core 308 , starting at the upper winding segments 316 , to provide further effective crack resistance.
- the upper metal end structure 330 may be in another interconnect level containing the upper winding segments 316 , possibly further reducing the fabrication cost.
- FIG. 4A through FIG. 4G depict an example method of forming the structure of FIG. 3 .
- the substrate 302 of the integrated fluxgate device 300 may be, for example, part of a semiconductor wafer such as a silicon wafer, or may be part of a dielectric substrate such as ceramic or sapphire, containing additional integrated fluxgate devices.
- the lower winding segments 312 and the lower metal end structure 328 are formed over the top surface 304 of the substrate 302 by an etched aluminum process.
- An example etched aluminum process of forming the lower winding segments 312 and the lower metal end structure 328 starts with forming a layer of interconnect metal over the top surface 304 .
- the layer of interconnect metal may include, for example, an adhesion layer of titanium nitride, a layer of aluminum with a few percent copper, silicon and/or titanium, 1 micron to 3 microns thick, and an anti-reflection layer of titanium nitride.
- An etch mask of photoresist is formed over the layer of interconnect metal which covers areas for the lower winding segments 312 and the lower metal end structure 328 .
- An RIE process using chlorine radicals is used to remove the layer of interconnect where exposed by the etch mask.
- the etch mask is subsequently removed, for example by an ash process, leaving the lower winding segments 312 and the lower metal end structure 328 over the top surface 304 of the substrate 302 .
- a first IMD layer 332 is formed over the lower winding segments 312 and the lower metal end structure 328 , and over exposed areas of the top surface 304 of the substrate 302 .
- the first IMD layer 332 may include, for example, a conformal layer of silicon nitride to provide a diffusion barrier on the aluminum layer in the lower winding segments 312 and the lower metal end structure 328 , and a layer of silicon dioxide on the layer of silicon nitride.
- the layer of silicon dioxide may be thicker than the lower winding segments 312 and the lower metal end structure 328 , and subsequently planarized by an oxide CMP process.
- Silicon nitride and silicon dioxide in the first IMD layer 332 may be formed by PECVD processes.
- a lower ILD layer 334 is formed over the first IMD layer 332 of FIG. 4B .
- the lower ILD layer 334 may be formed as described in reference to FIG. 2B .
- a layer of magnetic material 336 for the fluxgate core 308 of FIG. 3 is formed over the lower ILD layer 334 .
- the layer of magnetic material 336 may have a similar structure and composition to the layer of magnetic material described in reference to FIG. 2B .
- An etch mask 338 is formed over the layer of magnetic material 336 to cover the area for the fluxgate core 308 .
- an etch process removes the magnetic material from the layer of magnetic material 336 of FIG. 4C in the area exposed by the etch mask 338 to form the fluxgate core 308 .
- the etch process may be a wet etch process.
- the etch mask 338 is subsequently removed.
- an upper ILD layer 340 is formed over the lower ILD layer 334 and over the fluxgate core 308 .
- the upper ILD layer 340 includes a layer of silicon nitride and a main layer of silicon dioxide over the layer of silicon nitride, as described in reference to FIG. 2E .
- the main layer of silicon dioxide is planarized.
- the upper ILD layer 340 may include a cap layer of silicon nitride over the main layer of silicon dioxide.
- the upper ILD layer 340 may be formed by PECVD processes.
- the vias 318 are formed through the upper ILD layer 340 and through the lower ILD layer 334 to make electrical connections to the lower winding segments 312 of FIG. 4A .
- the vias 318 may be formed by a tungsten damascene process, with a metal liner of titanium and titanium nitride, and fill layer of tungsten formed by an MOCVD process using tungsten hexafluoride reduced by silane and hydrogen.
- a tungsten etchback process or a tungsten CMP process removes the metal liner and tungsten from over a top surface of the upper ILD layer 340 , leaving the vias 318 .
- the upper winding segments 316 and the upper metal end structure 330 are formed over the upper ILD layer 340 .
- the upper winding segments 316 make electrical connections to the vias 318 of FIG. 4F .
- the upper winding segments 316 and the upper metal end structure 330 may be formed by a similar process used for the lower winding segments 312 and the lower metal end structure 328 of FIG. 3 , as described in reference to FIG. 4A .
- a second IMD layer not shown, may be formed over the upper winding segments 316 and the upper metal end structure 330 .
- a protective overcoat and bond pads may be subsequently formed to complete fabrication of the integrated fluxgate device 300 .
- the structure of FIG. 1 may be formed using the method of FIG. 4A through FIG. 4G .
- the structure of FIG. 3 may be formed by the method of FIG. 2A through FIG. 2G .
- the structure of FIG. 1 and/or the structure of FIG. 3 may be formed using a masked plating process, in which a seed layer of metal is formed on an existing top surface of the integrated fluxgate device.
- a plating mask is formed which exposes areas for the lower winding segments and the lower metal end structure; the plating mask may include photoresist formed by a photolithographic process.
- the lower winding segments and the lower metal end structure are formed by electroplating metal such as copper on the seed layer in the areas exposed by the plating mask.
- the plating mask is subsequently removed, and the seed layer is removed where exposed by the lower winding segments and the lower metal end structure.
- the upper winding segments and the upper metal end structure may be formed by a similar process.
- the crack-resistant structures described herein may also be formed at other high stress locations around the fluxgate cores, in addition to the ends of the fluxgate cores.
Abstract
An integrated fluxgate device contains a fluxgate magnetometer sensor with a fluxgate core of a thin film magnetic material. Metal windings are disposed above and below the fluxgate core. The fluxgate core has at least one end with a width of at least 5 microns. The fluxgate magnetometer sensor has a crack-resistant structure at the end of the fluxgate core. The crack-resistant structure includes at least one of a laterally rounded contour of the fluxgate core at the end having corner radii of at least 2 microns, a lower metal end structure in the lower dielectric layer extending under the end of the fluxgate core, or an upper metal end structure in the upper dielectric layer extending over the end of the fluxgate core.
Description
- This disclosure relates to the field of microelectronic devices. More particularly, this disclosure relates to fluxgate magnetometer sensors in microelectronic devices.
- Fluxgate magnetometer sensors in microelectronic devices have thin film magnetic material in the fluxgate cores embedded in dielectric material. The fluxgate cores are typically more than a micron thick to provide a desired sensitivity for the sensor. There is commonly stress in the thin film magnetic material from the deposition process, and there is further stress from thermal cycling of the integrated fluxgate device due to thermal expansion mismatch between the fluxgate core and the surrounding dielectric material, which frequently causes mechanical failure of the sensor, such as cracking of the dielectric material surrounding the fluxgate core.
- The following presents a simplified summary in order to provide a basic understanding of one or more aspects of the disclosure. This summary is not an extensive overview of the disclosure, and is neither intended to identify key or critical elements of the disclosure, nor to delineate the scope thereof. Rather, the primary purpose of the summary is to present some concepts of the disclosure in a simplified form as a prelude to a more detailed description that is presented later.
- An integrated fluxgate device containing a fluxgate magnetometer sensor has a fluxgate core of a thin film magnetic material. The fluxgate magnetometer sensor has a crack-resistant structure at an end of the fluxgate core. The crack-resistant structure includes at least one of a laterally rounded contour of the fluxgate core at the end having corner radii of at least 2 microns, a lower metal end structure in the lower dielectric layer extending under the end of the fluxgate core, or an upper metal end structure in the upper dielectric layer extending over the end of the fluxgate core.
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FIG. 1 is an exploded view of an example integrated fluxgate device containing a fluxgate magnetometer sensor. -
FIG. 2A throughFIG. 2G depict an example method of forming the structure ofFIG. 1 . -
FIG. 3 is an exploded view of another example integrated fluxgate device containing a fluxgate magnetometer sensor. -
FIG. 4A throughFIG. 4G depict an example method of forming the structure ofFIG. 3 . - The present disclosure is described with reference to the attached figures. The figures are not drawn to scale and they are provided merely to illustrate the disclosure. Several aspects of the disclosure are described below with reference to example applications for illustration. It should be understood that numerous specific details, relationships, and methods are set forth to provide an understanding of the disclosure. One skilled in the relevant art, however, will readily recognize that the disclosure can be practiced without one or more of the specific details or with other methods. In other instances, well-known structures or operations are not shown in detail to avoid obscuring the disclosure. The present disclosure is not limited by the illustrated ordering of acts or events, as some acts may occur in different orders and/or concurrently with other acts or events. Furthermore, not all illustrated acts or events are required to implement a methodology in accordance with the present disclosure.
- An integrated fluxgate device containing a fluxgate magnetometer sensor has a fluxgate core of a thin film magnetic material. The fluxgate magnetometer sensor has a crack-resistant structure at an end of the fluxgate core. The crack-resistant structure includes at least one of a laterally rounded contour of the fluxgate core at the end having corner radii of at least 2 microns, a lower metal end structure extending under the end of the fluxgate core, or an upper metal end structure in the upper dielectric layer extending over the end of the fluxgate core. Tests performed in pursuit of the instant disclosure have shown corner radii of at least 2 microns to be effective in reducing instances of cracks in dielectric material surrounding the fluxgate core. The lower metal end structure and the upper metal end structure may include winding segments of windings around the fluxgate core. The lower metal end structure and the upper metal end structure may be electrically coupled to the windings. Alternatively, the lower metal end structure and the upper metal end structure may be electrically isolated from the windings.
- For the purposes of this disclosure, the terms “lateral” and “laterally” are understood to refer to a direction parallel to a plane of a top surface of the integrated fluxgate device, and the terms “vertical” and “vertically” are understood to refer to a direction perpendicular to the plane of the top surface of the integrated fluxgate device.
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FIG. 1 is an exploded view of an example integrated fluxgate device containing a fluxgate magnetometer sensor. The integratedfluxgate device 100 is formed on asubstrate 102. Thesubstrate 102 may include a semiconductor material such as silicon. Atop surface 104 of thesubstrate 102 includes dielectric material such as silicon dioxide or silicon nitride. The dielectric material may be, for example, an inter-level dielectric (ILD) of an interconnect region of the integratedfluxgate device 100. Interconnects such as vias may be exposed at thetop surface 104. The integratedfluxgate device 100 may include electronic circuits with active components such as transistors which are part of thefluxgate magnetometer sensor 106, referred to herein as thefluxgate sensor 106. - The
fluxgate sensor 106 includes afluxgate core 108 of thin film magnetic material. Thefluxgate core 108 may be, for example, 1 micron to 3 microns thick. Awidth 110 of thefluxgate core 108 may be, for example, 10 microns to 500 microns. Increasing the thickness and thewidth 110 of thefluxgate core 108 may desirably improve the sensitivity of thefluxgate sensor 106, but may undesirably increase a size and cost of the integratedfluxgate device 100. The thickness and thewidth 110 may be selected to provide a desired balance between sensitivity and cost. - The
fluxgate sensor 106 includeslower winding segments 112 ofwindings 114 around thefluxgate core 108. Thelower winding segments 112 include metal, and may be part of an interconnect level of the integratedfluxgate device 100. Thelower winding segments 112 are disposed under thefluxgate core 108. Thefluxgate sensor 106 further includesupper winding segments 116 of thewindings 114. Theupper winding segments 116 also include metal, and may be part of another interconnect level of the integratedfluxgate device 100. Theupper winding segments 116 are disposed over thefluxgate core 108. The upperwinding segments 116 may be electrically coupled to thelower winding segments 112 throughvias 118 of thewindings 114. Thevias 118 include metal and may be part of a via level of the integratedfluxgate device 100. Thewindings 114, including thelower winding segments 112, the upperwinding segments 116 and thevias 118, are electrically isolated from thefluxgate core 108 by layers of dielectric material, not shown inFIG. 1 in order to more clearly depict the spatial relationship between thefluxgate core 108, thelower winding segments 112, the upperwinding segments 116 and thevias 118. - The
fluxgate sensor 106 has a crack-resistant structure 120 at anend 122 of thefluxgate core 108. In the instant example, the crack-resistant structure 120 includes a laterallyrounded contour 124 of thefluxgate core 108 havingcorner radii 126 of at least 2 microns. In the instant example, thecorner radii 126 are approximately equal to half thewidth 110 of thefluxgate core 108 at theend 122, so that thefluxgate core 108 has a semicircular shape at theend 122. In the instant example, the crack-resistant structure 120 includes a lowermetal end structure 128 which extends under theend 122 of thefluxgate core 108. In the instant example, the lowermetal end structure 128 includes at least one of the lower windingsegments 112 which extend under theend 122 of thefluxgate core 108. In the instant example, the crack-resistant structure 120 includes an uppermetal end structure 130 which extends over theend 122 of thefluxgate core 108. In the instant example, the uppermetal end structure 130 includes at least one of the upper windingsegments 116 which extend over theend 122 of thefluxgate core 108. Forming the lowermetal end structure 128 and the uppermetal end structure 130 of the crack-resistant structure 120 of the lower windingsegments 112 and the upper windingsegments 116, respectively, may advantageously improve a sensitivity of thefluxgate sensor 106. Forming thefluxgate core 108 withcorner radii 126 approximately equal to half thewidth 110 of thefluxgate core 108 may advantageously provide increased crack resistance compared to smaller corner radii. - Each
end 122 of thefluxgate core 108 may have a version of the crackresistant structure 120. The crack-resistant structure 120 at afirst end 122 may be different from the crack-resistant structure 120 at asecond end 122. Thefluxgate sensor 106 may contain more than onefluxgate core 108. For example, thefluxgate sensor 106 may be a differential sensor with twofluxgate cores 108. Eachend 122 of eachfluxgate core 108 may have a version of the crackresistant structure 120. Further, theintegrated fluxgate device 100 may include more than onefluxgate sensor 106, for example to measure magnetic field components along perpendicular axes. The crack-resistant structure 120 may be formed at eachend 122 of eachfluxgate core 108 in theintegrated fluxgate device 100. -
FIG. 2A throughFIG. 2G depict an example method of forming the structure ofFIG. 1 . Referring toFIG. 2A , thesubstrate 102 of theintegrated fluxgate device 100 may be, for example, part of a semiconductor wafer such as a silicon wafer, or may be part of a dielectric substrate such as ceramic or sapphire, containing additional integrated fluxgate devices. In the instant example, a first intra-metal dielectric (IMD)layer 132 is formed over thetop surface 104 of thesubstrate 102. Thefirst IMD layer 132 may be, for example, 2 microns to 4 microns thick, and may include a main layer of silicon dioxide, and optionally an etch stop layer of silicon nitride, silicon carbide nitride or silicon carbide, and optionally a cap layer of silicon nitride or silicon carbide nitride. Silicon dioxide in thefirst IMD layer 132 may be formed by a plasma enhanced chemical vapor deposition (PECVD) process using tetraethyl orthosilicate (TEOS). Silicon nitride in thefirst IMD layer 132 may be formed by a PECVD process using bis(tertiary-butyl-amino) silane (BTBAS). - Trenches for the lower winding
segments 112 are formed through thefirst IMD layer 132 using reactive ion etch (RIE) processes, for a damascene process of forming the lower windingsegments 112. The trenches may expose tops of vias at thetop surface 104 of thesubstrate 102. A metal liner of tantalum and/or tantalum nitride is formed over thefirst IMD layer 132, extending into the trenches to provide a barrier for the lower windingsegments 112. A seed layer of copper is formed on the metal liner by a sputter process, and additional copper is formed on the seed layer by electroplating, filling the trenches with copper. Excess copper and the metal liner are removed from over a top surface of thefirst IMD layer 132 by a copper chemical mechanical polish (CMP) process, leaving the copper and metal liner in the trenches to form the lower windingsegments 112. The lower windingsegments 112 extend past the area for thefluxgate core 108 ofFIG. 1 , outlined inFIG. 2A by a dashed border. Instances of the lower windingsegments 112 extending under an end of thefluxgate core 108 are part of the lowermetal end structure 128 of the crack-resistant structure 120. Forming the lowermetal end structure 128 concurrently with the lower windingsegments 112 may advantageously reduce a fabrication cost of theintegrated fluxgate device 100. - Referring to
FIG. 2B , alower ILD layer 134 is formed over thefirst IMD layer 132 and over the lower windingsegments 112 ofFIG. 2A . Thelower ILD layer 134 may be, for example, 0.5 microns to 1 micron thick, and may include a main layer of silicon dioxide and optionally an etch stop layer. Thelower ILD layer 134 includes a cap layer of silicon nitride to provide a lower barrier for thefluxgate core 108 ofFIG. 1 . Thelower ILD layer 134 may be formed by PECVD processes, as described in reference toFIG. 2A . - A layer of
magnetic material 136 for thefluxgate core 108 ofFIG. 1 is formed over thelower ILD layer 134. The layer ofmagnetic material 136 may include a stack of alternating sub-layers of iron nickel and aluminum nitride. The layer ofmagnetic material 136 may be, for example, 1 micron to 2 microns thick, to provide a desired sensitivity for thefluxgate sensor 106. - An
etch mask 138 is formed over the layer ofmagnetic material 136 to cover the area for thefluxgate core 108. Theetch mask 138 may include photoresist formed by a photolithographic process, and may optionally include a layer of anti-reflection material such as a bottom anti-reflection coat (BARC). Theetch mask 138 has rounded corners with radii greater than 2 microns. - Referring to
FIG. 2C , an etch process removes the magnetic material from the layer ofmagnetic material 136 ofFIG. 2B in the area exposed by theetch mask 138. The magnetic material remaining under theetch mask 138 forms thefluxgate core 108. The etch process may be, for example, a wet etch process which is selective to the cap layer of silicon nitride at a top of thelower ILD layer 134. - Referring to
FIG. 2D , theetch mask 138 ofFIG. 2C is removed, leaving thefluxgate core 108 in place over thelower ILD layer 134. Theetch mask 138 may be removed, for example, using an ash process. - Referring to
FIG. 2E , anupper ILD layer 140 is formed over thelower ILD layer 134 and over thefluxgate core 108. Theupper ILD layer 140 includes a layer of silicon nitride to provide an upper barrier over thefluxgate core 108. Theupper ILD layer 140 further includes a main layer of silicon dioxide over the layer of silicon nitride, 2 microns to 4 microns thick. The main layer of silicon dioxide is planarized, for example by an oxide CMP process, to provide a suitable surface for subsequently forming the upper windingsegments 116 ofFIG. 1 by a damascene process. Theupper ILD layer 140 includes a cap layer of silicon nitride over the main layer of silicon dioxide. Theupper ILD layer 140 may be formed by PECVD processes, as described in reference toFIG. 2A . - Referring to
FIG. 2F , thevias 118 are formed through theupper ILD layer 140 and through thelower ILD layer 134 to make electrical connections to the lower windingsegments 112 ofFIG. 2A . Thevias 118 may be formed by a copper damascene process as described in reference toFIG. 2A . Alternatively, thevias 118 may be formed by a tungsten damascene process, with a metal liner of titanium and titanium nitride, and fill layer of tungsten formed by a metal organic chemical vapor deposition (MOCVD) process using tungsten hexafluoride reduced by silane and hydrogen. - Referring to
FIG. 2G , asecond IMD layer 142 is formed over theupper ILD layer 140. Thesecond IMD layer 142 may have a similar thickness, structure and composition to thefirst IMD layer 132, and may be formed by similar processes, as described in reference toFIG. 2A . Trenches for the upper windingsegments 116 are formed through thesecond IMD layer 142 using RIE processes. The trenches for the upper windingsegments 116 expose tops of thevias 118 ofFIG. 2F . The upper windingsegments 116 are formed in the trenches by a copper damascene process, as described in reference toFIG. 2A . The upper windingsegments 116 extend past the area for thefluxgate core 108 ofFIG. 1 , outlined inFIG. 2G by a dashed border. Instances of the upper windingsegments 116 extending over an end of thefluxgate core 108 are part of the uppermetal end structure 130 of the crack-resistant structure 120. Forming the uppermetal end structure 130 concurrently with the upper windingsegments 116 may advantageously reduce the fabrication cost of theintegrated fluxgate device 100. Forming the lowermetal end structure 128 ofFIG. 1 and the uppermetal end structure 130 of copper may advantageously improve the crack resistance of the crack-resistant structure 120, due to the high shear stress limit of copper compared to other commonly used interconnect metals. - Additional steps may be performed to complete fabrication of the
integrated fluxgate device 100. For example, a protective overcoat may be formed over thefluxgate sensor 106. Bond pads may be formed in the protective overcoat to provide electrical connections to components in theintegrated fluxgate device 100. -
FIG. 3 is an exploded view of another example integrated fluxgate device containing a fluxgate magnetometer sensor. Theintegrated fluxgate device 300 is formed on asubstrate 302. Thesubstrate 302 may include a semiconductor material such as silicon. Atop surface 304 of thesubstrate 302 includes dielectric material, possibly a top layer of an ILD layer of theintegrated fluxgate device 300. Vias may be exposed at thetop surface 304. Theintegrated fluxgate device 300 may include electronic circuits which are part of thefluxgate magnetometer sensor 306, referred to herein as thefluxgate sensor 306. - The
fluxgate sensor 306 includes afluxgate core 308 of thin film magnetic material. Thefluxgate core 308 may have a thickness of 1 micron to 3 microns thick, and awidth 310 of 10 microns to 500 microns. The thickness and thewidth 310 may be selected to provide a desired balance between sensitivity and cost, as described in reference toFIG. 1 . Thefluxgate sensor 306 includes lower windingsegments 312 ofwindings 314 around thefluxgate core 308. The lower windingsegments 312 include metal. The lower windingsegments 312 are disposed under thefluxgate core 308. In the instant example, the lower windingsegments 312 do not extend to anend 322 of thefluxgate core 308. Thefluxgate sensor 306 further includes upper windingsegments 316 of thewindings 314. The upper windingsegments 316 also include metal. The upper windingsegments 316 are disposed over thefluxgate core 308. In the instant example, the upper windingsegments 316 do not extend to theend 322 of thefluxgate core 308. The upper windingsegments 316 may be electrically coupled to the lower windingsegments 312 throughvias 318 of thewindings 314. Thevias 318 include metal. Thewindings 314, including the lower windingsegments 312, the upper windingsegments 316 and thevias 318, are electrically isolated from thefluxgate core 308 by layers of dielectric material, not shown inFIG. 3 in order to more clearly depict the spatial relationship between thefluxgate core 308 and thewindings 314. - The
fluxgate sensor 306 has a crack-resistant structure 320 at anend 322 of thefluxgate core 308. In the instant example, the crack-resistant structure 320 includes a laterally roundedcontour 324 of thefluxgate core 308 havingcorner radii 326 of at least 2 microns. In the instant example, thecorner radii 326 are less than half thewidth 310 of thefluxgate core 308 at theend 322, which may advantageously reduce an area of thefluxgate core 308, hence reducing an area of theintegrated fluxgate device 300 and so possibly further reducing a fabrication cost of theintegrated fluxgate device 300. - In the instant example, the crack-
resistant structure 320 includes a lowermetal end structure 328 which extends under theend 322 of thefluxgate core 308. In the instant example, the lowermetal end structure 328 is separate from the lower windingsegments 312. The lowermetal end structure 328 may be a single metal element, possibly with slots, as depicted inFIG. 3 . The metal in the lowermetal end structure 328 occupies at least 50 percent of an area directly under theend 322 of thefluxgate core 308, starting at the lower windingsegments 312, to provide effective crack resistance. The lowermetal end structure 328 may be in an interconnect level containing the lower windingsegments 312, possibly reducing the fabrication cost. - In the instant example, the crack-
resistant structure 320 includes an uppermetal end structure 330 which extends over theend 322 of thefluxgate core 308. In the instant example, the uppermetal end structure 330 is separate from the upper windingsegments 316. The uppermetal end structure 330 may be a single metal element, possibly with slots, as depicted inFIG. 3 . The metal in the uppermetal end structure 330 occupies at least 50 percent of an area directly over theend 322 of thefluxgate core 308, starting at the upper windingsegments 316, to provide further effective crack resistance. The uppermetal end structure 330 may be in another interconnect level containing the upper windingsegments 316, possibly further reducing the fabrication cost. -
FIG. 4A throughFIG. 4G depict an example method of forming the structure ofFIG. 3 . Referring toFIG. 4A , thesubstrate 302 of theintegrated fluxgate device 300 may be, for example, part of a semiconductor wafer such as a silicon wafer, or may be part of a dielectric substrate such as ceramic or sapphire, containing additional integrated fluxgate devices. In the instant example, the lower windingsegments 312 and the lowermetal end structure 328 are formed over thetop surface 304 of thesubstrate 302 by an etched aluminum process. An example etched aluminum process of forming the lower windingsegments 312 and the lowermetal end structure 328 starts with forming a layer of interconnect metal over thetop surface 304. The layer of interconnect metal may include, for example, an adhesion layer of titanium nitride, a layer of aluminum with a few percent copper, silicon and/or titanium, 1 micron to 3 microns thick, and an anti-reflection layer of titanium nitride. An etch mask of photoresist is formed over the layer of interconnect metal which covers areas for the lower windingsegments 312 and the lowermetal end structure 328. An RIE process using chlorine radicals is used to remove the layer of interconnect where exposed by the etch mask. The etch mask is subsequently removed, for example by an ash process, leaving the lower windingsegments 312 and the lowermetal end structure 328 over thetop surface 304 of thesubstrate 302. - Referring to
FIG. 4B , afirst IMD layer 332 is formed over the lower windingsegments 312 and the lowermetal end structure 328, and over exposed areas of thetop surface 304 of thesubstrate 302. Thefirst IMD layer 332 may include, for example, a conformal layer of silicon nitride to provide a diffusion barrier on the aluminum layer in the lower windingsegments 312 and the lowermetal end structure 328, and a layer of silicon dioxide on the layer of silicon nitride. The layer of silicon dioxide may be thicker than the lower windingsegments 312 and the lowermetal end structure 328, and subsequently planarized by an oxide CMP process. Silicon nitride and silicon dioxide in thefirst IMD layer 332 may be formed by PECVD processes. - Referring to
FIG. 4C , alower ILD layer 334 is formed over thefirst IMD layer 332 ofFIG. 4B . Thelower ILD layer 334 may be formed as described in reference toFIG. 2B . A layer ofmagnetic material 336 for thefluxgate core 308 ofFIG. 3 is formed over thelower ILD layer 334. The layer ofmagnetic material 336 may have a similar structure and composition to the layer of magnetic material described in reference toFIG. 2B . Anetch mask 338 is formed over the layer ofmagnetic material 336 to cover the area for thefluxgate core 308. - Referring to
FIG. 4D , an etch process removes the magnetic material from the layer ofmagnetic material 336 ofFIG. 4C in the area exposed by theetch mask 338 to form thefluxgate core 308. The etch process may be a wet etch process. Theetch mask 338 is subsequently removed. - Referring to
FIG. 4E , anupper ILD layer 340 is formed over thelower ILD layer 334 and over thefluxgate core 308. Theupper ILD layer 340 includes a layer of silicon nitride and a main layer of silicon dioxide over the layer of silicon nitride, as described in reference toFIG. 2E . The main layer of silicon dioxide is planarized. Theupper ILD layer 340 may include a cap layer of silicon nitride over the main layer of silicon dioxide. Theupper ILD layer 340 may be formed by PECVD processes. - Referring to
FIG. 4F , thevias 318 are formed through theupper ILD layer 340 and through thelower ILD layer 334 to make electrical connections to the lower windingsegments 312 ofFIG. 4A . Thevias 318 may be formed by a tungsten damascene process, with a metal liner of titanium and titanium nitride, and fill layer of tungsten formed by an MOCVD process using tungsten hexafluoride reduced by silane and hydrogen. A tungsten etchback process or a tungsten CMP process removes the metal liner and tungsten from over a top surface of theupper ILD layer 340, leaving thevias 318. - Referring to
FIG. 4G , the upper windingsegments 316 and the uppermetal end structure 330 are formed over theupper ILD layer 340. The upper windingsegments 316 make electrical connections to thevias 318 ofFIG. 4F . The upper windingsegments 316 and the uppermetal end structure 330 may be formed by a similar process used for the lower windingsegments 312 and the lowermetal end structure 328 ofFIG. 3 , as described in reference toFIG. 4A . A second IMD layer, not shown, may be formed over the upper windingsegments 316 and the uppermetal end structure 330. A protective overcoat and bond pads may be subsequently formed to complete fabrication of theintegrated fluxgate device 300. - The structure of
FIG. 1 may be formed using the method ofFIG. 4A throughFIG. 4G . The structure ofFIG. 3 may be formed by the method ofFIG. 2A throughFIG. 2G . Alternatively, the structure ofFIG. 1 and/or the structure ofFIG. 3 may be formed using a masked plating process, in which a seed layer of metal is formed on an existing top surface of the integrated fluxgate device. A plating mask is formed which exposes areas for the lower winding segments and the lower metal end structure; the plating mask may include photoresist formed by a photolithographic process. The lower winding segments and the lower metal end structure are formed by electroplating metal such as copper on the seed layer in the areas exposed by the plating mask. The plating mask is subsequently removed, and the seed layer is removed where exposed by the lower winding segments and the lower metal end structure. The upper winding segments and the upper metal end structure may be formed by a similar process. The crack-resistant structures described herein may also be formed at other high stress locations around the fluxgate cores, in addition to the ends of the fluxgate cores. - While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only and not limitation. Numerous changes to the disclosed embodiments can be made in accordance with the disclosure herein without departing from the spirit or scope of the invention. Thus, the breadth and scope of the present disclosure should not be limited by any of the above described embodiments. Rather, the scope of the disclosure should be defined in accordance with the following claims and their equivalents.
Claims (27)
1. An integrated fluxgate device, comprising:
a substrate having a top surface comprising a dielectric material;
a fluxgate core disposed above the top surface of the substrate, the fluxgate core having a crack-resistant structure at an end of the fluxgate core;
wherein the crack-resistant structure comprises at least one of:
a laterally rounded contour positioned at the end having corner radii of at least 2 microns;
a lower metal end structure extending under the end of the fluxgate core; or
an upper metal end structure extending over the end of the fluxgate core.
2. The integrated fluxgate device of claim 1 , wherein the crack-resistant structure comprises the laterally rounded contour of the fluxgate core at the end, wherein the corner radii are approximately equal to half of a width of the fluxgate core at the end.
3. The integrated fluxgate device of claim 1 , wherein the crack-resistant structure comprises the lower metal end structure and the upper metal end structure, wherein the lower metal end structure comprises at least one of lower winding segments disposed under the fluxgate core, and the upper metal end structure comprises at least one of upper winding segments disposed over the fluxgate core.
4. The integrated fluxgate device of claim 1 , wherein the crack-resistant structure comprises the lower metal end structure, wherein the lower metal end structure comprises a lower metal element which is separate from lower winding segments disposed under the fluxgate core.
5. The integrated fluxgate device of claim 4 , wherein the lower metal element and the lower winding segments are contained in a metal layer of the integrated fluxgate device.
6. The integrated fluxgate device of claim 4 , wherein the lower metal element occupies at least 50 percent of an area directly under the end of the fluxgate core.
7. The integrated fluxgate device of claim 1 , wherein the crack-resistant structure comprises the upper metal end structure, wherein the upper metal end structure comprises an upper metal element which is separate from upper winding segments disposed over the fluxgate core,
8. The integrated fluxgate device of claim 7 , wherein the upper metal element and the upper winding segments are contained in a metal layer of the integrated fluxgate device.
9. The integrated fluxgate device of claim 7 , wherein the upper metal element occupies at least 50 percent of an area directly over the end of the fluxgate core.
10. The integrated fluxgate device of claim 1 , wherein the crack-resistant structure comprises the lower metal end structure, wherein the lower metal end structure comprises copper.
11. The integrated fluxgate device of claim 1 , wherein the crack-resistant structure comprises the lower metal end structure, wherein the lower metal end structure comprises aluminum.
12. The integrated fluxgate device of claim 1 , wherein the fluxgate core comprises iron and nickel.
13. The integrated fluxgate device of claim 1 , wherein the fluxgate core is electrically isolated from lower winding segments disposed under the fluxgate core by a first intra-level dielectric (ILD) layer comprising silicon dioxide, disposed between the fluxgate core and the lower winding segments.
14. The integrated fluxgate device of claim 13 , wherein the fluxgate core is electrically isolated from the upper winding segments disposed over the fluxgate core by a second ILD layer comprising silicon dioxide, disposed between the fluxgate core and the upper winding segments.
15. A method, comprising:
forming a fluxgate core above a top surface of a substrate, the fluxgate core comprising magnetic material; and
forming a crack-resistant structure at the end of the fluxgate core, wherein the crack-resistant structure comprises at least one of:
a laterally rounded contour of the fluxgate core at the end having corner radii of at least 2 microns;
a lower metal end structure extending under the end of the fluxgate core; or
an upper metal end structure extending over the end of the fluxgate core.
16. The method of claim 15 , wherein the crack-resistant structure comprises the laterally rounded contour of the fluxgate core at the end, the corner radii being approximately equal to half of a width of the fluxgate core at the end.
17. The method of claim 15 , wherein forming the fluxgate core comprises:
forming a layer of magnetic material over the lower dielectric layer;
forming an etch mask over the layer of magnetic material, the mask covering an area for a fluxgate core, the etch mask having radii of at least 2 microns at corners of the end;
removing the layer of magnetic material where exposed by the etch mask to form the fluxgate core; and
subsequently removing the etch mask;
18. The method of claim 15 , wherein the crack-resistant structure comprises the lower metal end structure and the upper metal end structure, the lower metal end structure comprising at least one of lower winding segments, and the upper metal end structure comprising at least one of upper winding segments.
19. The method of claim 15 , wherein the crack-resistant structure comprises the lower metal end structure, and wherein forming the lower metal end structure comprises forming a lower metal element which is separate from lower winding segments, concurrently with the lower winding segments.
20. The method of claim 19 , wherein the lower metal element occupies at least 50 percent of an area directly under the end of the fluxgate core.
21. The method of claim 15 , wherein the crack-resistant structure comprises the upper metal end structure, and wherein forming the upper metal end structure comprises forming an upper metal element which is separate from upper winding segments, concurrently with the upper winding segments.
22. The method of claim 21 , wherein the upper metal element occupies at least 50 percent of an area directly over the end of the fluxgate core.
23. The method of claim 15 , wherein the crack-resistant structure comprises the lower metal end structure, wherein forming the lower metal end structure comprises a copper damascene process.
24. The method of claim 15 , wherein the crack-resistant structure comprises the lower metal end structure, and wherein forming the lower metal end structure comprises an etched aluminum process, comprising:
forming a layer of interconnect metal comprising aluminum over the top surface of the substrate;
forming an etch mask over the layer of interconnect metal, wherein the etch mask covers an area for the lower metal end structure;
removing the layer of interconnect metal where exposed by the etch mask, leaving the layer of interconnect metal under the etch mask to form the lower metal end structure; and
subsequently removing the etch mask.
25. The method of claim 15 , wherein forming the fluxgate core comprises forming a layer of the magnetic material comprising iron and nickel by a sputtering process.
26. The method of claim 15 , further comprising the step of forming an ILD layer comprising silicon dioxide over lower winding segments before forming the fluxgate core.
27. The method of claim 15 , further comprising the step of forming an ILD layer comprising silicon dioxide over the fluxgate core before forming upper winding segments.
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US15/042,119 US20170234942A1 (en) | 2016-02-11 | 2016-02-11 | Layouts for interlevel crack prevention in fluxgate technology manufacturing |
US16/503,660 US20190331742A1 (en) | 2016-02-11 | 2019-07-05 | Layouts for interlevel crack prevention in fluxgate technology manufacturing |
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US7041526B2 (en) * | 2003-02-25 | 2006-05-09 | Samsung Electronics Co., Ltd. | Magnetic field detecting element and method for manufacturing the same |
KR100691467B1 (en) * | 2005-10-19 | 2007-03-09 | 삼성전자주식회사 | Fluxgate sensor comprising conbzr magnetic core, and, fabrication method thereof |
US8558344B2 (en) * | 2011-09-06 | 2013-10-15 | Analog Devices, Inc. | Small size and fully integrated power converter with magnetics on chip |
JP6353642B2 (en) * | 2013-02-04 | 2018-07-04 | 株式会社トーキン | Magnetic core, inductor, and module with inductor |
US10718826B2 (en) * | 2014-12-02 | 2020-07-21 | Texas Instruments Incorporated | High performance fluxgate device |
US9799721B2 (en) * | 2015-04-17 | 2017-10-24 | Taiwan Semiconductor Manufacturing Company, Ltd. | Integrated magnetic core inductor and methods of fabrications thereof |
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