Apparatus for removing native oxide layers from silicon wafers

Abstract

A method and apparatus for selectively removing a native oxide layer from a silicon wafer without significantly affecting the underlying silicon or other material, that may be thereon, by exposing the silicon wafer to an etchant gas including NF 3 while simultaneously exposing the wafer to ultraviolet radiation, and heating the wafer to a temperature of 100-400° C.

1 . A method of selectively removing a native oxide layer from a silicon wafer without significantly affecting the underlying silicon or other materials that may be there on, comprising exposing the silicon wafer to an etchant gas including NF 3  while simultaneously exposing the wafer to ultraviolet radiation and heating the wafer to a temperature of 100-400° C.  
     
     
         2 . The method according to  claim 1  wherein the wafer is heated to a temperature of 250-350° C.  
     
     
         3 . The method according to  claim 1 , wherein the wafer is heated to a temperature of approximately 300° C.  
     
     
         4 . The method according to  claim 1 , wherein said etchant gas also includes N 2 .  
     
     
         5 . The method according to  claim 4 , wherein said etchant gas includes N 2  in approximately equal proportions by volume with NF 3 .  
     
     
         6 . The method according to  claim 1 , wherein the partial pressure of the etchant gas is 10-300 Torr.  
     
     
         7 . The method according to  claim 1 , wherein the partial pressure of the etchant gas is below 100 Torr.  
     
     
         8 . The method according to  claim 7 , wherein the partial pressure of the etchant gas is 30-60 Torr.  
     
     
         9 . A method of selectively removing a native oxide layer from a silicon wafer without significantly affecting the underlying silicon, or without significantly removing a polysilicon or thermal oxide deposition that may be thereon, comprising: exposing the silicon wafer to an etchant gas including NF 3 at a partial pressure of 10 to 300 Torr, while exposing the wafer to ultraviolet radiation, and while heating the wafer to a temperature of 100-400° C.  
     
     
         10 . The method according to  claim 9 , wherein the wafer is heated to a temperature of 250-350° C.  
     
     
         11 . The method according to  claim 10 , wherein the wafer is heated to a temperature of approximately 300° C.  
     
     
         12 . The method according to  claim 9 , wherein said etchant gas also includes N 2 .  
     
     
         13 . The method according to  claim 12 , wherein said etchant gas includes N 2  in approximately equal proportions by volume with NF 3 .  
     
     
         14 . The method according to  claim 9 , wherein the partial pressure of the etchant gas is 30-60 Torr.  
     
     
         15 . Apparatus for selectively removing a native oxide layer from a silicon wafer without significantly affecting the underlying silicon of other materials that may be there on, comprising: 
 a heating chamber including a supporting member for supporting the wafer from which native oxide layer is to be selectively removed;    a heater for heating a wafer on the supporting member to a temperature of 100-400° C.;    a gas supply for introducing into said chamber an etchant gas including NF 3 ;    and an ultraviolet source for irradiating the wafer with ultraviolet radiation while the wafer is exposed to said etchant gas and is heated to said temperature of 100-400° C.    
     
     
         16 . The apparatus according to  claim 15 , wherein said heater heats the wafer to a temperature of 250-350° C.  
     
     
         17 . The apparatus according to  claim 15 , wherein said heater heats the wafer to a temperature of approximately 300° C.  
     
     
         18 . The apparatus according to  claim 15 , wherein said gas supply introduces N 2  with said NF 3 .  
     
     
         19 . The method according to  claim 15 , wherein the partial pressure of the etchant gas is 10-300 Torr.  
     
     
         20 . The apparatus according to  claim 20 , wherein the partial pressure of the etchant gas is 30-60 Torr.  
     
     
         21 . The apparatus according to  claim 15 , wherein said heater is an infrared lamp heater.  
     
     
         22 . The apparatus according to  claim 15 , wherein said wafer supporting member is of graphite.  
     
     
         23 . The apparatus according to  claim 15 , wherein said chamber is of quartz.  
     
     
         24 . The apparatus according to  claim 23  wherein said heater is an infrared lamp heater and is located externally of said quartz chamber below said wafer supporting member, and said ultraviolet source is an ultraviolet lamp located externally of said chamber above said wafer supporting member.