Method and apparatus for thermal gas purging

Abstract

A plasma etching chamber is cleaned with a supply of pressurized nitrogen or argon that is electrically heated. The cleaning cycle is performed during the idle time following an etching cycle. Electrically heated cleaning gas flows into the etching chamber for a predetermined period during which the etching chamber rises. Flow of heated cleaning gas is then stopped, and the etching chamber is evacuated by existing equipment. The cycle can be started automatically using a pressure signal from a conventional purging gas line or from a signal at a SECS/GEM port.

1 . An apparatus for cleaning a plasma etching chamber with a cleaning gas, comprising 
 A) means for electrically heating the cleaning gas stream;    B) means for detecting when the etching chamber enters an idle condition;    C) means for controlling flow of cleaning gas to the etching chamber, and    D) means for measuring and controlling the temperature of the cleaning gas that flows to the etching chamber.    
     
     
         2 . An apparatus as recited in  claim 1 , wherein the etching chamber has a purge gas line, further comprising a pressure sensor for detecting when the etching chamber enters an idle condition by sensing a rise in pressure in the purge gas line.  
     
     
         3 . An apparatus as recited in  claim 1 , further comprising means for regulating the pressure of the cleaning gas that flows to the etching chamber.  
     
     
         4 . An apparatus for cleaning a plasma etching chamber comprising 
 A) an electrical heater    B) means for detecting when the etching chamber enters an idle condition;    C) a control valve connected in a cleaning gas line between the electrical heater and the etching chamber, and    D) a temperature sensor located at or near the outlet of the electrical heater, and    E) means for controlling the temperature of the cleaning gas that flows to the etching chamber.    
     
     
         5 . An apparatus as recited in  claim 4 , further comprising a pressure regulator installed in the cleaning gas line.  
     
     
         6 . A method for cleaning a plasma etching chamber used in manufacturing semiconductor devices with a cleaning gas, comprising the steps of: 
 A) detecting when the etching chamber enters an idle condition;    B) heating the cleaning gas;    C) measuring and controlling the temperature of the heated cleaning gas;    C) causing heated cleaning gas to flow into the etching chamber for a predetermined interval; and    D) following step (C), stopping the flow of heated cleaning gas into the etching chamber and evacuating the etching chamber for a predetermined interval.    
     
     
         7 . A method for cleaning a plasma etching chamber as recited in  claim 6 , further comprising the step of regulating the pressure of the cleaning gas that flows into the etching chamber.  
     
     
         8 . A method for cleaning a plasma etching chamber as recited in  claim 6 , further comprising the step of stopping flow of cleaning gas to the etching chamber when the etching chamber initiates an etching cycle.