High Purity Target Manufacturing Methods

Abstract

A method for producing a high purity tungsten sputtering target. The method includes heat treating of high purity tungsten powder in order to consolidate it into a blank with density providing closed porosity. The consolidation may be achieved by hot pressing, HIP or any other appropriate method. Next, this plate is rolled to produce target blanks of approximate size and further increased density of the material. The method may be applicable to a variety of blanks including round shape target blanks, for example, consisting of tungsten, molybdenum, tantalum, hafnium, etc.

1 . Method of preparing a metal or metal alloy sputter target comprising: 
 a) providing metal or metal alloy powder particles wherein said metal is a member of Groups IV, V, or VI of the periodic chart, said powder having a purity of at least 5Ns;    b) pressure consolidating said particle to form a blank having a density of greater than about 95% of the theoretical density;    c) increasing the density of said blank to at least about 99% density; and    d) forming said increased density blank into a shape required for a sputter target, said target having at least a 5Ns.    
   
   
       2 . Method as recited in  claim 1  wherein said step b) further comprises heating.  
   
   
       3 . Method as recited in clam 1 wherein said step c) of increasing the density comprises increasing said density to about 100% density.  
   
   
       4 . Method as recited in  claim 1  wherein said blank has a 6N purity.  
   
   
       5 . Method as recited in  claim 3  wherein said metal or metal alloy particles are chosen from the group consisting of W, Ta, Mo, and Hf.  
   
   
       6 . Method as recited in  claim 5  wherein said pressure consolidation b) comprises hot pressing or HIPing said powder particles.  
   
   
       7 . Method as recited in  claim 6  wherein said step c) comprises thermomechanically rolling said blank.  
   
   
       8 . Method as recited in  claim 7  wherein said thermomechanical rolling is carried out at a temperature of from about 1400° C.-1700° C.  
   
   
       9 . Method as recited in  claim 8  wherein said blank is reduced in size (thickness) in an amount of 40% and greater during said thermomechanical rolling, said blank exhibiting substantially closed porosity as a result of said thermo-mechanical rolling.  
   
   
       10 . Method as recited in  claim 9  wherein said metal or metal alloy comprises W.  
   
   
       11 . Method of preparing a W or W alloy sputter target comprising: 
 a) providing W powder particles having a particle size of less than about 100 um;    b) pressure consolidating said particles to form a plate having a density of greater than about 95% of the theoretical density;    c) thermomechanically rolling the plate material so that it has a density of above about 97.5% of the theoretical density.    
   
   
       12 . Method as recited in  claim 11  wherein said thermo-mechanical rolling of the plate material results in a density of about 99% and greater.  
   
   
       13 . Method as recited in  claim 12  wherein said thermo-mechanical rolling of said plate material results in a density of about 100%.  
   
   
       14 . Method as recited in  claim 13  wherein said step of pressure consolidating said particles comprises hot isostatically pressing said particles at a temperature of about 1,000° C. to about 1900° C. for about 1 to 10 hours at a pressure of about 15 Ksi and greater.  
   
   
       15 . Method as recited in  claim 14  wherein said step of pressure consolidating said particles comprises hot pressing said particles at a temperature of about 1400° C. to 2000° C. and at a pressure of about 25 to about 500 Kg/cm 2 .  
   
   
       16 . Method as recited in  claim 15  wherein said hot pressing is carried out under vacuum conditions.  
   
   
       17 . Method as recited in  claim 11  wherein said thermomechanical rolling comprises rolling said plate at a temperature of about 1400° C. to 1700° C. resulting in a thickness reduction of greater than about 40%.  
   
   
       18 . Method as recited in  claim 17  comprising rolling said plate at a temperature of about 1500° C.  
   
   
       19 . Method as recited in  claim 11  further comprising d) forming said thermomechanically rolled plate into the size required for a sputter target, said target having at least 5N purity.  
   
   
       20 . Method as recited in  claim 19  wherein said target has an average grain size of less than about 100 um.  
   
   
       21 . Method as recited in  claim 20  wherein said target has an oxygen content of less than about 100 ppm.