Warm Wafer After Ion Cryo-Implantation

Abstract

Embodiments of an ion cryo-implantation process utilize a post implantation heating stage to heat the implanted wafer while under the heavy vacuum used during cryo-implantation. The implanted wafer is then transferred to load locks which are held at a lesser vacuum than the heavy vacuum.

What is claimed is: 
     
         1 . An apparatus comprising:
 a first load lock, the first load lock configured to be maintained at a first pressure;   a processing chamber comprising:
 a cooling stage, the cooling stage configured to cool a wafer to a first temperature prior to ion implantation, the first temperature corresponding to a cryogenic temperature, 
 an implantation platen, the implantation platen configured to retain the wafer during an ion implantation process, and 
 a heating stage, the heating stage configured to heat the wafer after implantation to a second temperature; and 
   a second load lock, the second load lock configured to be maintained at the first pressure, wherein the processing chamber is configured to be maintained at a second pressure lower than the first pressure.   
     
     
         2 . The apparatus of  claim 1 , wherein the heating stage and the implantation platen are in a continuous vacuum space, wherein a first vacuum level surrounding the implantation platen and a second vacuum level surrounding the heating stage are the same. 
     
     
         3 . The apparatus of  claim 1 , wherein the processing chamber comprises a first vacuum pump of a first type, wherein the first load lock comprises a second vacuum pump of a second type different than the first type. 
     
     
         4 . The apparatus of  claim 1 , wherein the heating stage comprises:
 an overhead electric heater, a heated platform, or a combination thereof.   
     
     
         5 . The apparatus of  claim 1 , wherein the implantation platen is disposed in a first subchamber of the processing chamber, wherein the heating stage is disposed in a second subchamber of the processing chamber, and wherein the second subchamber is attached to a wall of the first subchamber. 
     
     
         6 . The apparatus of  claim 5 , wherein the second subchamber comprises a cryo pump attached to the second subchamber. 
     
     
         7 . The apparatus of  claim 1 , further comprising:
 a robot configured to move the wafer from the first load lock to the cooling stage, to move the wafer from the cooling stage to the implantation platen, to move the wafer from the implantation platen to the heating stage, and to move the wafer from the heating stage to the second load lock.   
     
     
         8 . The apparatus of  claim 1 , further comprising two or more cryo pumps for providing a first vacuum level between 100 and 1000 times greater than a second vacuum level of the second load lock. 
     
     
         9 . The apparatus of  claim 1 , wherein the second temperature is within 10° C. of a temperature of the second load lock. 
     
     
         10 . A processing tool comprising:
 an ion implantation chamber comprising:
 a cooling stage, the cooling stage configured to cool a wafer to a first temperature prior to ion implantation; 
 an implantation platen, the implantation platen configured to retain the wafer during an ion implantation process; and 
 a heating stage, the heating stage configured to heat the wafer after implantation to a second temperature greater than the first temperature, wherein the heating stage is disposed in a same vacuum environment as the implantation platen; 
   an outgoing load lock disposed at a lower vacuum environment than the first heating stage and the implantation platen; and
 a robot configured to move the wafer from the heating stage to the outgoing load lock after heating the wafer to the second temperature. 
   
     
     
         11 . The processing tool of  claim 10  further comprising an incoming load lock disposed at a lower vacuum environment than the first heating stage and the implantation platen, wherein the robot is configured to move the wafer from the incoming load lock to the cooling stage. 
     
     
         12 . The processing tool of claim ii, wherein the incoming load lock and the outgoing load lock are disposed at a same vacuum level. 
     
     
         13 . The processing tool of  claim 10  further comprising a vacuum pump mounted to a sidewall of the heating stage. 
     
     
         14 . The processing tool of  claim 10 , wherein the first temperature is a cryogenic temperature. 
     
     
         15 . The processing tool of  claim 10 , wherein a vacuum level of implantation platen is 2 to 3 orders of magnitude greater than the outgoing load lock. 
     
     
         16 . An apparatus comprising:
 a processing chamber comprising:
 a cooling stage configured to cool a wafer to a first temperature in a range of −100° C. and −30° C.; 
 an implantation platen configured to hold the wafer during an ion implantation process performed after cooling the wafer to the first temperature; and 
 a heating stage configured to heat the wafer to a second temperature in a range of 0° C. and 50° C. after the ion implantation process; 
   an outgoing load lock;   a slit valve between the outgoing load lock and the processing chamber, wherein the slit valve is configured to separate a first vacuum environment of the processing chamber from a second vacuum environment of the outgoing load lock, and wherein the first vacuum environment is two to three levels of magnitude higher than the second vacuum environment; and   a robot configured to move the wafer from the heating stage to the outgoing load lock after heating the wafer to the second temperature.   
     
     
         17 . The apparatus of  claim 16 , wherein the heating stage comprises electric heating coils configured to heat the wafer to the second temperature. 
     
     
         18 . The apparatus of  claim 16 , wherein the heating stage comprises:
 a platform configured to hold the wafer while heating the wafer to the second temperature; and   heating loops configured to circulate a heated liquid through the platform while heating the wafer to the second temperature.   
     
     
         19 . The apparatus of  claim 16 , wherein the implantation platen is disposed in a first subchamber of the processing chamber, wherein the heating stage is disposed in a second subchamber of the processing chamber, and wherein no slit valve separates the second subchamber from the first subchamber. 
     
     
         20 . The apparatus of  claim 1 , wherein the second temperature is within 10° C. of a temperature of the second load lock.