Batch photoresist dry strip and ash system and process

Abstract

Photoresist stripping is provided that employs batch processing to maximize throughput and an upstream plasma activation source using vapor or gas processing to efficiently create reactive species and minimize chemical consumption. An upstream plasma activation source efficiently creates reactive species remote from the photoresist on the substrate surfaces. Either a remote plasma generator upstream of the processing chamber or an integrated plasma unit within the processing chamber upstream of the processing volume may be used. Plasma processing gas is introduced from a side of a stack of wafers and flows across the wafers. Processing gas may be forced across the surfaces of the wafers in the column to an exhaust on the opposite side of the column, and the column may be rotated. An upstream plasma activation source enables a strip process to occur at low temperatures, for example below 600 degrees C., which are particularly advantageous in BEOL process flow. Integrated processes that combine dry and wet-like sequential processes are also provided. Oxidizing, reducing or fluorine-containing plasma can be employed. Wet stripping, using, for example, wafer vapor or ozone or both may be included, simultaneously or sequentially.

1 . An apparatus for removing photo-resist from semiconductor wafers comprising:
 a vacuum chamber having a substrate-support column therein for supporting a plurality of semiconductor wafers in a vertical stack thereon;   a processing gas inlet coupled to the chamber and configured to introduce process gas into the chamber along one side of the column;   an exhaust outlet coupled to the chamber and configured to remove gas from the chamber from a side thereof opposite said one side;   a plasma generator situated in-line with the processing gas inlet and operable to form a plasma in process gas being introduced along said one side of the column; and   a gas flow control system coupled to the inlet and the outlet and configured to flow process gas containing plasma from said one side of the column and horizontally across surfaces of wafers supported on the column and toward the outlet.   
   
   
       2 . The apparatus of  claim 1  wherein:
 the substrate-support column being rotatable about a vertical axis to rotate the semiconductor wafers supported thereon.   
   
   
       3 . The apparatus of  claim 1  wherein:
 the plasma generator includes a remote plasma generating unit connected to the inlet upstream thereof and operable to form a plasma in process gas flowing from a source thereof to the processing gas inlet.   
   
   
       4 . The apparatus of  claim 1  wherein:
 the plasma generator includes a plasma generating system situated in the chamber between the processing gas inlet and the column and operable to form a plasma in process gas flowing from the inlet to the wafers supported on the column.   
   
   
       5 . The apparatus of  claim 1  further comprising:
 a wet strip process fluid supply connected to the processing chamber and operable to supply ozone, water vapor or a mixture containing ozone and water vapor to the processing chamber.   
   
   
       6 . The apparatus of  claim 1  wherein:
 the gas flow control system is operable to flow a reactive gas plasma at a rate of from 1,000 sccm to 10,000 sccm through the chamber, and maintaining pressure in the chamber at from 100 milliTorr to 10 Torr.   
   
   
       7 . The apparatus of  claim 1  wherein:
 the column includes a temperature control system operable to maintain temperature of wafers on the column in the range of from 100 degrees C. to 600 degrees C.   
   
   
       8 . The apparatus of  claim 1  further comprising:
 a source of reactive gas connected to the inlet.   
   
   
       9 . The apparatus of  claim 8  wherein the source of reactive gas includes:
 means for providing to the plasma gas generator either:
 oxidizing chemistry, or 
 reducing chemistry, or 
 fluorine-containing chemistry, or 
 oxidizing fluorine-containing chemistry, or 
 reducing fluorine-containing chemistry. 
   
   
   
       10 . The apparatus of  claim 8  wherein the source of reactive gas includes:
 means for providing to the plasma gas generator either:
 oxidizing chemistry containing either O 2 , NO, N 2 O, or inert gas in combination with O 2 , NO, or N 2 O, or 
 reducing chemistry containing either H 2 , NH 3 , or inert gas in combination with H 2  or NH 3 , or 
 either F 2 , NF 3 , CF 4 , or inert gas in combination with F 2 , NF 3  or CF 4 .