Layouts for interlevel crack prevention in fluxgate technology manufacturing

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.

What is claimed is: 
     
         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.