High Quality Single Crystal and Method of Growing the Same

Abstract

Disclosed is a method of growing a single crystal from a melt contained in a crucible. The method includes the step of making the temperature of a melt increase gradually to a maximum point and then decrease gradually along the axis parallel to the lengthwise direction of the single crystal from the interface of the single crystal and the melt to the bottom of the crucible. The increasing temperature of the melt is kept to preferably have a greater temperature gradient than the decreasing temperature thereof. Preferably, the axis is set to pass through the center of the single crystal. Preferably, the convection of the inner region of the melt is made smaller than that of the outer region thereof.

1 . A single crystal grown from a melt in such a condition that the temperature of said melt increases gradually to a maximum point and then decreases gradually along the vertical axis parallel to the lengthwise direction of said single crystal from the interface of said single crystal and said melt to the bottom of said crucible, the increasing temperature of said melt being kept to have a greater temperature gradient than the decreasing temperature thereof. 
   
   
       2 . A single crystal as defined in  claim 1 , said single crystal being grown according to one of the Czochralski method, modified Czochralski method, top-seeded solution growth method, floating zone method, and Bridgman method in such a condition that the convection of the inner region of said melt is smaller than that of the outer region thereof, and said vertical axis is arranged through the center of said single crystal. 
   
   
       3 . A single crystal as defined in  claim 1 , comprising a single element like Si or Ge, or a compound like GaAs, InP, LN (LiNbO 3 ), LT (LiTaO 3 ), YAG (yttrium aluminum garnet), LBO (LiB 3 O 5 ), or CLBO (CsLiB 6 O 10 ). 
   
   
       4 . A wafer prepared by using a single crystal grown from a melt, wherein said single crystal is produced by growing from a melt in such a condition that the temperature of said melt increases gradually to a maximum point and then decreases gradually along the vertical axis parallel to the lengthwise direction of said single crystal from the interface of said single crystal and said melt to the bottom of said crucible, the increasing temperature of said melt being kept to have a greater temperature gradient than the decreasing temperature thereof. 
   
   
       5 . A wafer as defined in  claim 4 , characterized in that the quality distribution of said wafer is substantially asymmetric about the center thereof. 
   
   
       6 . A wafer as defined in  claim 5 , characterized in that interstitial prevalent regions and vacancy prevalent regions appear asymmetric about the center of said wafer.