Adding SF.sub.6 gas to improve metal undercut for hardmask metal etching
 A new method of etching metal lines using SF.sub.6 gas during the overetch step to prevent undercutting of the anti-reflective coating layer is described. Semiconductor device structures are provided in and on a semiconductor substrate. The semiconductor device structures are covered with an insulating layer. A barrier metal layer is deposited overlying the insulating layer. A metal layer is deposited overlying the barrier metal layer. A silicon oxide layer is deposited overlying the metal layer. The silicon oxide layer is covered with a layer of photoresist which is exposed, developed, and patterned to form the desired photoresist mask. The silicon oxide layer is etched away where it is not covered by the photoresist mask leaving a patterned hard mask. The metal layer is etched away where it is not covered by the patterned hard mask to form metal lines. Overetching is performed to remove the barrier layer where it is not covered by the hard mask wherein SF.sub.6 gas is one of the etchant gases used in the overetching whereby fluorine ions from the SF.sub.6 gas react with the metal layer and the barrier metal layer to form a passivation layer on the sidewalls of the metal lines thereby preventing undercutting of the metal lines resulting in metal lines having a vertical profile. The photoresist mask is removed and fabrication of the integrated circuit device is completed. 
Taiwan Semiconductor Manufacturing Company
Y H C
Y10S H01L C23F
additional inventional inventional
Chia-Shiung Yu-Hua
Tsai Lee