US 11,056,392 B2
FinFET devices having gate stacks with protruding parts and method of forming the same
Cheng-Chien Li, Hsinchu County (TW); Wei-Shuo Ho, New Taipei (TW); Huang-Chao Chang, Hsinchu (TW); and Wei-Zhe Jhang, Taoyuan (TW)
Assigned to Taiwan Semiconductor Manufacturing Company, Ltd., Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Co., Ltd., Hsinchu (TW)
Filed on Mar. 29, 2018, as Appl. No. 15/939,304.
Prior Publication US 2019/0304842 A1, Oct. 3, 2019
Int. Cl. H01L 29/66 (2006.01); H01L 21/8234 (2006.01); H01L 29/78 (2006.01); H01L 27/088 (2006.01)
CPC H01L 21/823431 (2013.01) [H01L 27/0886 (2013.01); H01L 29/6681 (2013.01); H01L 29/66545 (2013.01); H01L 29/7848 (2013.01); H01L 29/7851 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for forming a FinFET device, comprising:
patterning a substrate to form fins;
forming a dummy gate stack on the substrate and over the fins, wherein forming the dummy gate stack comprises:
forming a dummy layer covering the fins;
forming a hard mask layer over the dummy layer;
performing a first etching step to remove portions of the dummy layer and portions of the hard mask layer with a bromine containing etching gas as a main etching gas in the first etching step to form a dummy strip and a hard mask strip, wherein after the first etching step, the dummy strip is formed with a first part located over the fins, and a plurality of tapered second parts in physical contact with sidewalls of the first part and sidewalls of the fins, and the hard mask strip overlaps with the first part of the dummy strip and does not overlap with the plurality of tapered second parts of the dummy strip, and the first etching step reveals portions of the fins; and
performing a second etching step to remove portions of the plurality of tapered second parts of the dummy strip from the sidewalls of the first part and from the sidewalls of the fins with a chlorine containing etching gas to form the dummy gate stack, wherein the chlorine containing etching gas is selected as a main etching gas in the second etching step on the basis that it has a smaller molecular weight of ion as compared to the bromine containing etching gas;
forming a blanket layer over the dummy gate stack, and performing an etching of the blanket layer to form spacers located on both sides of the dummy gate stack; and
replacing the dummy gate stack with a gate stack.