Texas Instruments Corporation

Byron J R Shulver

William David French

Thomas Dyer Bonifield

Ricky A Jackson

Dok Won Lee

Neil Gibson

Mona M Eissa

Erika Lynn Mazotti

Sudtida Lavangkul

Sopa Chevacharoenkul

Mark L Jenson

Lee Alan Stringer

Mark R Kimmich

An integrated fluxgate device has a magnetic core disposed over a semiconductor substrate. A first winding is disposed in a first metallization level above and a second metallization level below the magnetic core, and is configured to generate a first magnetic field in the magnetic core. A second winding is disposed in the first and second metallization levels and is configured to generate a second magnetic field in the magnetic core. A third winding is disposed in the first and second metallization levels and is configured to sense a magnetic field in the magnetic core that is the net of the first and second magnetic fields.

Highly sensitive, low power fluxgate magnetic sensor integrated onto semiconductor process technologies

An integrated fluxgate device has a magnetic core on a control circuit. The magnetic core has a volume and internal structure sufficient to have low magnetic noise and low non-linearity. A stress control structure is disposed proximate to the magnetic core. An excitation winding, a sense winding and a compensation winding are disposed around the magnetic core. An excitation circuit disposed in the control circuit is coupled to the excitation winding, configured to provide current at high frequency to the excitation winding sufficient to generate a saturating magnetic field in the magnetic core during each cycle at the high frequency. An isolation structure is disposed between the magnetic core and the windings, sufficient to enable operation of the excitation winding and the sense winding at the high frequency at low power.

A method comprises forming an etch stop layer, a first titanium layer, a magnetic core, a second titanium layer, and patterning the first and second titanium layers. The etch stop layer is formed above a substrate. The first titanium layer is formed on the etch stop layer. The magnetic core is formed on the first titanium layer. The second titanium layer has a first portion encapsulating the magnetic core with the first titanium layer, and a second portion interfacing with the first titanium layer beyond the magnetic core. The patterning of the first and second titanium layers includes forming a mask over a magnetic core region and etching the first and second titanium layers exposed by the mask using a titanium etchant and a titanium oxide etchant.

Selective patterning of titanium encapsulation layers

Selective patterning of an integrated fluxgate device

A microelectronic device is formed by forming a stack of alternating layers of a magnetic material and a dielectric material. An etch mask is formed over the magnetic laminate layer. An aqueous wet etch including 5 percent to 10 percent nitric acid, 0.5 percent to 2 percent sulphuric acid, and 0.5 percent to 3 percent hydrofluoric acid is used to etch the magnetic laminate layer where exposed by the etch mask to form a patterned magnetic laminate layer. An optional adhesion layer, if present, is also removed by the aqueous wet etch solution where exposed by the etch mask. The etch mask is subsequently removed.

Method for patterning of laminated magnetic layer

Growing community of inventors

Wylie, TX, United States of America

Byron J R Shulver