Texas Instruments Corporation

Yousong Zhang

Mona M Eissa

Fuchao Wang

Jonathan Philip Davis

Neal T Murphy

Brian E Zinn

Mark L Jenson

Dok Won Lee

Byron Shulver

An integrated magnetic device has a magnetic core which includes layers of the magnetic material located in a trench in a dielectric layer. The magnetic material layers are flat and parallel to a bottom of the trench, and do not extend upward along sides of the trench. The integrated magnetic device is formed by forming layers of the magnetic material over the dielectric layer and extending into the trench. A protective layer is formed over the magnetic material layers. The magnetic material layers are removed from over the dielectric layer, leaving the magnetic material layers and a portion of the protective layer in the trench. The magnetic material layers along sides of the trench are subsequently removed. The magnetic material layers along the bottom of the trench provide the magnetic core.

Magnetic core for integrated magnetic devices

Method to form magnetic core for integrated magnetic devices

An etchant for simultaneously etching NiFe and AlN with approximately equal etch rates that comprises phosphoric acid, acetic acid, nitric acid and deionized water. Alternating layers of NiFe and AlN may be used to form a magnetic core of a fluxgate magnetometer in an integrated circuit. The wet etch provides a good etch rate of the alternating layers with good dimensional control and with a good resulting magnetic core profile. The alternating layers of NiFe and AlN may be encapsulated with a stress relief layer. A resist pattern may be used to define the magnetic core geometry. The overetch time of the wet etch may be controlled so that the magnetic core pattern extends at least 1.5 um beyond the base of the magnetic core post etch. The photo mask used to form the resist pattern may also be used to form a stress relief etch pattern.

Process for NiFe fluxgate device

A method of fabricating a semiconductor device includes aligning an alignment structure of a wafer to a direction of a magnetic field created by an external electromagnet and depositing a magnetic layer (e.g., NiFe) over the wafer in the presence of the magnetic field and while applying the magnetic field and maintaining a temperature of the wafer below 150&#xb0; C. An insulation layer (e.g., AlN) is deposited on the first magnetic layer. The alignment structure of the wafer is again aligned to the direction of the magnetic field and a second magnetic layer is deposited on the insulation layer, in the presence of the magnetic field and while maintaining the temperature of the wafer below 150&#xb0; C.

Magnetic core

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Yousong Zhang