Vacancy-dominated, defect-free silicon

Abstract

The present invention relates to single crystal silicon, in ingot or wafer form, having an axially symmetric vacancy dominated region and an axially symmetric silicon self-interstitial dominated region. Both the vacancy dominated and the silicon self-interstitial dominated regions are substantially free of agglomerated intrinsic point defects. The vacancy dominated region has a radial width of at least 15 mm and/or includes the central axis and the silicon self-interstitial dominated region is annular in shape and extends radially outward from the vacancy dominated region to the peripheral edge of the ingot or wafer. In ingot form, the axially symmetric regions have an axial length which is at least 20% of the length of the constant diameter portion of the ingot.

1 . A single crystal silicon wafer having a central axis, a front side and a back side which are generally perpendicular to the central axis, a circumferential edge, a radius extending from the central axis to the circumferential edge of the wafer, and a nominal diameter of about 150 mm, about 200 mm, or greater than about 200 mm, the wafer comprising: 
 a first axially symmetric region in which vacancies are the predominant intrinsic point defect and which is substantially free of agglomerated vacancy intrinsic point defects wherein the first axially symmetric region comprises the central axis or has a radial width of at least about 15 mm; and,    a second axially symmetric region in which silicon self-interstitial atoms are the predominant intrinsic point defect and which is substantially free of agglomerated silicon self-interstitial intrinsic point defects, wherein the second axially symmetric region extends radially from the first axially symmetric region to the circumferential edge.    
   
   
       2 . The wafer of claim  41  wherein the first axially symmetric region comprises the central axis.  
   
   
       3 . The wafer of claim  41  wherein the width of the first axially symmetric region is at least about 25% of the radius.  
   
   
       4 . The wafer of claim  43  wherein the first axially symmetric region comprises the central axis.  
   
   
       5 . The wafer of claim  41  wherein the width of the first axially symmetric region is at least about 50% of the radius.  
   
   
       6 . The wafer of claim  45  wherein the first axially symmetric region comprises the central axis.  
   
   
       7 . The wafer of claim  41  wherein the width of the first axially symmetric region is at least about 60% of the radius.  
   
   
       8 . The wafer of claim  47  wherein the first axially symmetric region comprises the central axis.  
   
   
       9 . The wafer of claim  41  wherein the wafer has as oxygen content which is less than about 13 PPMA.  
   
   
       10 . The wafer of claim  41  wherein the wafer has as oxygen content which is less than about 11 PPMA.  
   
   
       11 . The wafer of claim  41  wherein the wafer has an absence of oxygen precipitate nucleation centers.  
   
   
       12 . A single crystal silicon ingot having a central axis, a seed-cone, an end-cone, and a constant diameter portion between the seed-cone and the end-cone having a circumferential edge, a radius extending from the central axis to the circumferential edge, and a nominal diameter of about 150 mm, about 200 mm, or greater than about 200 mm, the single crystal silicon ingot being characterized in that after the ingot is grown and cooled from the solidification temperature, the constant diameter portion comprises: 
 a first axially symmetric region in which vacancies are the predominant intrinsic point defect and which is substantially free of agglomerated intrinsic point defects wherein the first axially symmetric region comprises the central axis or has a width of at least about 15 mm and has a length as measured along the central axis of at least about 20% of the length of the constant diameter portion of the ingot; and,    a second axially symmetric region in which silicon self-interstitial atoms are the predominant intrinsic point defect and which is substantially free of agglomerated silicon self-interstitial intrinsic point defects, wherein the second axially symmetric region extends radially from the first axially symmetric region to the circumferential edge and has a length equal to about the length of the first axially symmetric region.    
   
   
       13 . The single crystal silicon ingot of claim  52  wherein the length of the first axially symmetric region is at least about 40% the length of the constant diameter portion of the ingot.  
   
   
       14 . The single crystal silicon ingot of claim  52  wherein the first axially symmetric region comprises the central axis.  
   
   
       15 . The single crystal silicon ingot of claim  52  wherein the length of the first axially symmetric region is at least about 60% the length of the constant diameter portion of the ingot.  
   
   
       16 . The single crystal silicon ingot of claim  55  wherein the first axially symmetric region comprises the central axis.  
   
   
       17 . The single crystal silicon ingot of claim  52  wherein the length of the first axially symmetric region is at least about 80% the length of the constant diameter portion of the ingot.  
   
   
       18 . The single crystal silicon ingot of claim  57  wherein the first axially symmetric region comprises the central axis.  
   
   
       19 . The single crystal silicon ingot of claim  52  wherein the width of the first axially symmetric region is at least about 25% of the radius.  
   
   
       20 . The single crystal silicon ingot of claim  59  wherein the first axially symmetric region comprises the central axis.  
   
   
       21 . The single crystal silicon ingot of claim  59  wherein the length of the first axially symmetric region is at least about 40% the length of the constant diameter portion of the ingot.  
   
   
       22 . The single crystal silicon ingot of claim  52  wherein the first axially symmetric region comprises the central axis.  
   
   
       23 . The single crystal silicon ingot of claim  59  wherein the length of the first axially symmetric region is at least about 60% the length of the constant diameter portion of the ingot.  
   
   
       24 . The single crystal silicon ingot of claim  63  wherein the first axially symmetric region comprises the central axis.  
   
   
       25 . The single crystal silicon ingot of claim  59  wherein the length of the first axially symmetric region is at least about 80% the length of the constant diameter portion of the ingot.  
   
   
       26 . The single crystal silicon ingot of claim  52  wherein the width of the first axially symmetric region is at least about 50% of the radius.  
   
   
       27 . The single crystal silicon ingot of claim  66  wherein the first axially symmetric region comprises the central axis.  
   
   
       28 . The single crystal silicon ingot of claim  66  wherein the length of the first axially symmetric region is at least about 40% the length of the constant diameter portion of the ingot.  
   
   
       29 . The single crystal silicon ingot of claim  68  wherein the first axially symmetric region comprises the central axis.  
   
   
       30 . The single crystal silicon ingot of claim  66  wherein the length of the first axially symmetric region is at least about 60% the length of the constant diameter portion of the ingot.  
   
   
       31 . The single crystal silicon ingot of claim  70  wherein the first axially symmetric region comprises the central axis.  
   
   
       32 . The single crystal silicon ingot of claim  66  wherein the length of the first axially symmetric region is at least about 80% the length of the constant diameter portion of the ingot.  
   
   
       33 . The single crystal silicon ingot of claim  72  wherein the first axially symmetric region comprises the central axis.