US 6,982,175 B2
End point detection in time division multiplexed etch processes
David Johnson, Palm Harbor, Fla. (US); and Russell Westerman, Largo, Fla. (US)
Assigned to Unaxis USA Inc., St. Petersburg, Fla. (US)
Filed on Feb. 02, 2004, as Appl. No. 10/770,839.
Claims priority of provisional application 60/447594, filed on Feb. 14, 2003.
Prior Publication US 2004/0175913 A1, Sep. 09, 2004
Int. Cl. H01L 21/302 (2006.01)
U.S. Cl. 438—9 20 Claims
OG exemplary drawing
 
1. A method for establishing endpoint in a plasma etching process, the method comprising the steps of:
placing a substrate in a vacuum chamber;
etching a material from the substrate by means of a plasma;
depositing a passivation layer on the substrate by means of a plasma;
performing a process loop of repeating the etching step and the deposition step;
monitoring a variation in a plasma emission intensity at a characteristic frequency corresponding to the repetitive rate of the etching step or the deposition step of the process loop step;
discontinuing the process loop step based on said monitoring step; and
removing the substrate from the vacuum chamber.