Full density Co-W magnetic sputter targets

Abstract

A sputter target is provided with a first elemental phase of a first material, the first material being either cobalt or tungsten, a first intermetallic phase including the first material and a second material, the second material being either tungsten or cobalt and different from the first material, the first material in a greater atomic percentage than the second material, and a second intermetallic phase including the second material and the first material, the second material in a greater atomic percentage than the first material. The sputter target includes 20-80 at. % cobalt, and has a density greater than 99% of a theoretical maximum density thereof. The sputter target is fabricated by selecting a cobalt powder and a tungsten powder having the same particle size distribution, blending the cobalt powder and the tungsten powder to form a blended powder, canning the blended powder, hot pressing the blended powder to form a solid, and machining the solid to form a sputter target.

1 . A method of fabricating a sputter target, the method comprising the steps of:
 selecting a cobalt powder having a particle size distribution and a tungsten powder having the same particle size distribution;   blending the cobalt powder and the tungsten powder to form a blended powder;   canning the blended powder;   hot pressing the blended powder to form a solid; and   machining the solid to form a sputter target.   
     
     
         2 . The method according to  claim 1 , wherein the solid has a density greater than 99% of a theoretical maximum density thereof. 
     
     
         3 . The method according to  claim 1 , wherein the particle size distribution is between about 20 and 250 microns. 
     
     
         4 . The method according to  claim 1 , wherein the particle size distribution is between about 40 and 150 microns. 
     
     
         5 . The method according to  claim 1 , wherein the hot pressing is hot isostatic pressing which includes:
 heating to a first soak temperature between about 500° C. and 1050° C.,   holding at the first soak temperature for between about 15 and 120 minutes,   heating to a second soak temperature between about 1050° C. and 1450° C. and pressurizing to a pressure between about 15 ksi and about 45 ksi, and   holding at the second soak temperature and at the pressure between about 15 ksi and about 45 ksi for between about 20 to 360 minutes.   
     
     
         6 . The method according to  claim 1 , wherein the hot pressing is hot isostatic pressing which includes:
 heating to about 800° C. and holding at about 800° C. for about 60 minutes,   heating to about 1050° C., pressurizing to about 29 ksi and holding at about 1050° C. and about 29 ksi for about 240 minutes, and   heating to about 1236° C., maintaining a pressure of about 29 ksi and holding at about 1236° C. and about 29 ksi for about 60 minutes.   
     
     
         7 . The method according to  claim 6 , wherein the hot isostatic pressing further includes:
 cooling from about 1236° C. to about 800° C. at a rate of about 2° C./minute,   holding at about 800° C. for about 60 min, and   cooling from about 800° C. to about 400° C. at a rate of about 3° C./minute.   
     
     
         8 . The method according to  claim 1 , wherein the cobalt powder is a powder of elemental cobalt. 
     
     
         9 . The method according to  claim 1 , wherein the tungsten powder is a powder of elemental tungsten. 
     
     
         10 . The method according to  claim 1 , further comprising the step of sputtering the sputter target to form a film including cobalt and tungsten. 
     
     
         11 . A film sputtered according to the method of  claim 10 . 
     
     
         12 . A cobalt-tungsten sputter target, comprising:
 a first elemental phase of a first material, the first material being either cobalt or tungsten;   a first intermetallic phase including the first material and a second material, the second material being either tungsten or cobalt and different from the first material, the first material in a greater atomic percentage than the second material; and   a second intermetallic phase including the second material and the first material, the second material in a greater atomic percentage than the first material,   wherein the sputter target includes 20-80 at. % cobalt, and   wherein a density of the sputter target is greater than 99% of a theoretical maximum density thereof.   
     
     
         13 . The sputter target of  claim 12 , wherein the first intermetallic phase is a layer surrounding the first elemental phase. 
     
     
         14 . The sputter target of  claim 12 , further comprising a second elemental phase of the second material. 
     
     
         15 . The sputter target of  claim 14 , wherein the second intermetallic phase is a layer surrounding the second elemental phase. 
     
     
         16 . The sputter target of  claim 14 , wherein the second elemental phase has a cross-sectional dimension of between about 5 microns and about 150 microns. 
     
     
         17 . The sputter target of  claim 12 , wherein the first elemental phase has a cross-sectional dimension of between about 5 microns and about 150 microns. 
     
     
         18 . The sputter target of  claim 12 , wherein each of the first intermetallic phase and the second intermetallic phase has a thickness of between about 10 microns and about 100 microns. 
     
     
         19 . The sputter target of  claim 12 , wherein the sputter target includes 40-60 at. % cobalt. 
     
     
         20 . The sputter target of  claim 12 , wherein a cross section of the sputter target includes an average of less than 10 voids per square millimeter. 
     
     
         21 . The sputter target of  claim 20 , wherein the voids have an average size of less than 5 microns. 
     
     
         22 . The sputter target of  claim 12 , wherein a cross section of the sputter target includes an average of less than 20 cracks per square millimeter. 
     
     
         23 . The sputter target of  claim 22 , wherein the cracks have an average length of less than 150 microns.