Nonmagnetic material-dispersed fe-pt based sputtering target

Abstract

Provided is a sputtering target which can lower a heat treatment temperature for ordering a Fe—Pt magnetic phase and can suppress generation of particles during sputtering. The sputtering target is a nonmagnetic material-dispersed sputtering target containing Fe, Pt and Ge. The sputtering target includes at least one magnetic phase satisfying a composition represented by (Fe 1-α Pt α ) 1-β Ge β , as expressed in an atomic ratio for Fe, Pt and Ge, in which α and β represent numbers meeting 0.35≤α≤0.55 and 0.05≤β≤0.2, respectively. The magnetic phase has a ratio (S Ge30mass% /S Ge ) of 0.5 or less. The ratio (S Ge30mass% /S Ge ) is an average area ratio of Ge-based alloy phases containing a Ge concentration of 30% by mass or more (S Ge30mass% ) to an area ratio of Ge (S Ge ) calculated from the entire composition of the sputtering target, in element mapping by EPMA of a polished surface obtained by polishing a cross section perpendicular to a sputtering surface of the sputtering target.

1 . A nonmagnetic material-dispersed sputtering target containing Fe, Pt and Ge, the sputtering target comprising at least one magnetic phase satisfying a composition represented by (Fe 1-α Pt α ) 1-β Ge β  in an atomic ratio for Fe, Pt and Ge, in which α and β represent numbers meeting 0.35≤α≤0.55 and 0.05≤β≤0.2, respectively; wherein the magnetic phase satisfies a ratio (S Ge30mass% /S Ge ) of 0.5 or less, the ratio (S Ge30mass% /S Ge ) being a proportion of an average area ratio of Ge-based alloy phases containing Ge at a concentration of 30% by mass or more (S Ge30mass% ) to an area ratio of Ge (S Ge ) calculated from an entire composition of the sputtering target, in element mapping by EPMA of a polished surface obtained by polishing a cross section perpendicular to a sputtering surface of the sputtering target. 
     
     
         2 . The sputtering target according to  claim 1 , wherein the nonmagnetic material comprises one or more selected from the group consisting of carbon, carbide, oxide and nitride, and wherein the nonmagnetic material accounts for a volume fraction of from 10 to 60 vol % based on a total volume of the sputtering target. 
     
     
         3 . The sputtering target according to  claim 1 , wherein the sputtering target comprises one or more third elements selected from the group consisting of Au, B, Co, Cr, Cu, Mn, Mo, Nb, Ni, Pd, Re, Rh, Ru, Sn, Ta, W, V and Zn, in an amount of 10 at. % or less as expressed by a ratio of a total number of atoms of the third element(s) to a total number of atoms of Fe, Ge and Pt. 
     
     
         4 . The sputtering target according to  claim 1 , wherein the sputtering target has an oxygen concentration of 400 ppm by mass or less. 
     
     
         5 . A method for producing the sputtering target according to  claim 1 , comprising steps of:
 mixing Pt—Ge alloy powder and/or Pt—Ge—Fe alloy powder, metal powder other than the Pt—Ge alloy powder and the Pt—Ge—Fe alloy powder, and nonmagnetic material powder while pulverizing said powders in an inert gas atmosphere to obtain a mixed powder, such that Fe, Pt and Ge satisfy a composition represented by (Fe 1-α Pt α ) 1-β Ge β  in an atomic ratio for Fe, Pt and Ge, in which α and β represent numbers meeting 0.35≤α≤0.55 and 0.05≤β≤0.2, respectively;   sintering the mixed powder obtained in the above step by a pressure sintering method at a temperature of less than a melting point of the Pt—Ge alloy powder in a vacuum atmosphere or an inert gas atmosphere to obtain a sintered compact; and   shaping the sintered compact.   
     
     
         6 . The method for producing the sputtering target according to  claim 5 , wherein the Pt—Ge alloy powder and/or Pt—Ge—Fe alloy powder has an average particle diameter of from 1 μm to 50 μm before the mixing step. 
     
     
         7 . The method for producing the sputtering target according to  claim 5 , wherein when using the Pt—Ge alloy powder, the Pt—Ge alloy powder before the mixing step comprises a composition Pt:Ge=1:0.8 to 1.2 in an atomic ratio. 
     
     
         8 . The method for producing the sputtering target according to  claim 5 , wherein when using the Pt—Ge—Fe alloy powder, the Pt—Ge—Fe alloy powder before the mixing step comprises a composition Pt:Ge:Fe=1:0.8 to 1.2:0.1 to 0.3 in an atomic ratio. 
     
     
         9 . The method for producing the sputtering target according to  claim 5 , wherein the method comprises pressurizing the mixed powder at a pressure in a range of from 20 to 70 MPa during the sintering. 
     
     
         10 . The method for producing the sputtering target according to  claim 5 , wherein the mixed powder obtained by the step of mixing the powders while pulverizing them has an average particle diameter of 20 μm or less.