Method For Growing Germanium Epitaxial Films

Abstract

A method for growing germanium epitaxial films is disclosed. Initially, a silicon substrate is preconditioned with hydrogen gas. The temperature of the preconditioned silicon substrate is then decreased, and germane gas is flowed over the preconditioned silicon substrate to form an intrinsic germanium seed layer. Next, a mixture of germane and phosphine gases can be flowed over the intrinsic germanium, seed layer to produce an n-doped germanium seed layer. Otherwise, a mixture of diborane and germane gases can be flowed over the intrinsic germanium seed layer to produce a p-doped germanium seed layer. At this point, a hulk germanium layer can be grown on top of the doped germanium seed layer.

1 . A method for growing germanium epitaxial films, said method comprising:
 preconditioning a silicon substrate with hydrogen gas at a first temperature;   decreasing said first temperature of said preconditioned silicon substrate to a second temperature;   flowing germane gas over said preconditioned silicon substrate to form an intrinsic germanium seed layer;   increasing said second temperature of said preconditioned silicon substrate to a third temperature;   flowing a mixture of diborane and germane gases over said intrinsic germanium seed layer to produce an p-doped germanium layer; and   growing a hulk germanium film layer on top of said p-doped germanium layer.   
     
     
         2 . The method of  claim 1 , wherein said preconditioning further includes preconditioning said silicon substrate with hydrogen gas at approximately 3E −4  mBar for approximately 60 minutes at approximately 750 EC. 
     
     
         3 . The method of  claim 1 , wherein said decreasing further includes decreasing said first temperature from approximately 750 EC to approximately 350 EC at approximately 2 EC per minute. 
     
     
         4 . The method of  claim 1 , wherein said flowing germane gas further includes flowing germane gas over said preconditioned silicon substrate at approximately 1.5E −3  mBar for approximately 120 minutes. 
     
     
         5 . The method of  claim 1 , wherein said increasing further includes increasing said second temperature of said preconditioned silicon substrate from approximately 350 EC to approximately 600 EC at approximately 2 EC per minute. 
     
     
         6 . The method of  claim 1 , wherein said mixture diborane and germane gases includes an approximately 1:1 mixture of diborane and germane gases. 
     
     
         7 . The method of  claim 1 , wherein said mixture of diborane and germane gases is flowed over said germanium seed layer at approximately 6E −4  mBar for approximately 30 minutes. 
     
     
         8 . The method of  claim 1 , wherein said bulk germanium film layer is intrinsic germanium film. 
     
     
         9 . The method of  claim 1 , wherein said bulk germanium film layer is doped germanium film. 
     
     
         10 . The method of  claim 1 , wherein said growing further includes flowing germane gas over said preconditioned germanium layer at approximately 1.5E −3  mBar for approximately 480 minutes.