Defect-free junction formation using octadecaborane self-amorphizing implants

Abstract

A method and apparatus for implanting a semiconductor substrate with boron clusters. A substrate is implanted with octadecaborane by plasma immersion or ion beam implantation. The substrate surface is then annealed to completely dissociate and activate the boron clusters. The annealing may take place by melting the implanted regions or by a sub-melt annealing process.

1 . A method of treating a substrate, comprising:
 implanting boron macromolecules into a surface of the substrate;   melting the surface of the substrate implanted with the boron macromolecules;   resolidifying the surface of the substrate implanted with the boron macromolecules; and   annealing the surface of the substrate.   
     
     
         2 . The method of  claim 1 , wherein the boron macromolecules comprise clusters containing at least sixteen boron atoms. 
     
     
         3 . The method of  claim 1 , wherein melting the surface of the substrate implanted with boron macromolecules comprises directing heating energy to portions of the substrate surface to increase a temperature of the substrate surface to a point at or above the melting point of the substrate surface. 
     
     
         4 . The method of  claim 3 , wherein the heating energy comprises electromagnetic energy. 
     
     
         5 . The method of  claim 3 , wherein the heating energy comprises laser light. 
     
     
         6 . The method of  claim 5 , wherein the laser light is continuous wave radiation. 
     
     
         7 . The method of  claim 5 , wherein the laser light is pulsed. 
     
     
         8 . The method of  claim 1 , wherein resolidifying the surface of the substrate comprises cooling the surface at a rate less than 200° C./sec. 
     
     
         9 . The method of  claim 1 , wherein resolidifying the surface of the substrate comprises cooling the surface at a rate selected to eliminate crystal defects from the surface of the substrate. 
     
     
         10 . The method of  claim 1 , wherein annealing the surface of the substrate comprises maintaining the substrate surface at a temperature of at least 400° C. for at least 1 minute. 
     
     
         11 . The method of  claim 1 , wherein the boron macromolecules comprise octadecaborane. 
     
     
         12 . A method of treating a substrate, comprising:
 implanting octadecaborane into the surface of the substrate; and   annealing implanted regions of the substrate by repeatedly heating and cooling the implanted regions.   
     
     
         13 . The method of  claim 12 , wherein the octadecaborane is implanted at an energy level less than about 1 keV. 
     
     
         14 . The method of  claim 12 , wherein repeatedly heating and cooling the implanted regions comprises directing laser energy toward the implanted regions. 
     
     
         15 . The method of  claim 14 , further comprising pre-heating the substrate. 
     
     
         16 . The method of  claim 14 , wherein repeatedly heating and cooling the implanted regions comprises maintaining a temperature of the implanted regions at a temperature less than a melting temperature of the implanted regions. 
     
     
         17 . The method of  claim 12 , wherein repeatedly heating and cooling the implanted regions comprises exposing the implanted regions to pulses of electromagnetic radiation. 
     
     
         18 . The method of  claim 17 , wherein the electromagnetic radiation comprises laser light. 
     
     
         19 . The method of  claim 18 , wherein each implanted region is exposed to at least 30 pulses of electromagnetic radiation. 
     
     
         20 . The method of  claim 19 , wherein each pulse of electromagnetic radiation has a duration from about 1 nsec to about 10 μsec.