US 10,892,348 B2
Method of rounding fin-shaped structure
Hao-Hsuan Chang, Kaohsiung (TW); Bin-Siang Tsai, Changhua County (TW); Ting-An Chien, Tainan (TW); and Yi-Liang Ye, Kaohsiung (TW)
Assigned to UNITED MICROELECTRONICS CORP., Hsin-Chu (TW)
Filed by UNITED MICROELECTRONICS CORP., Hsin-Chu (TW)
Filed on Apr. 29, 2019, as Appl. No. 16/396,788.
Prior Publication US 2020/0343371 A1, Oct. 29, 2020
Int. Cl. H01L 29/66 (2006.01); H01L 21/62 (2006.01); H01L 21/02 (2006.01); H01L 21/265 (2006.01); H01L 21/308 (2006.01); H01L 21/762 (2006.01); H01L 29/78 (2006.01)
CPC H01L 29/66795 (2013.01) [H01L 21/0228 (2013.01); H01L 21/02236 (2013.01); H01L 21/26513 (2013.01); H01L 21/308 (2013.01); H01L 21/76224 (2013.01); H01L 29/7854 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A method of rounding fin-shaped structures, comprising:
providing a substrate comprising fin-shaped structures, and pad oxide caps and pad nitride caps stacked from bottom to top covering top surfaces of the fin-shaped structures from bottom to top;
forming an isolation structure by filling in spaces between the fin-shaped structures;
performing a removing process to remove a top part of the isolation structure and expose the pad oxide caps, the pad nitride caps and top parts of the fin-shaped structures;
performing an oxidation process to oxidize sidewalls of the top parts of the fin-shaped structures, thereby forming oxidized parts covering sidewalls of the top parts of the fin-shaped structures;
removing the pad nitride caps;
and removing the pad oxide caps and the oxidized parts at the same time, thereby forming rounded fin-shaped structures;
forming an oxide layer conformally covering the isolation structure and the rounded fin-shaped structures;
performing an implantation process to form wells in the rounded fin-shaped structures;
and removing the oxide layer after the implantation process is performed.