US 12,224,176 B2
Method for forming fin structure in fin field effect transistor process and fin structure
Xiaobo Guo, Shanghai (CN)
Assigned to Shanghai Huali Integrated Circuit Corporation, Shanghai (CN)
Filed by Shanghai Huali Integrated Circuit Corporation, Shanghai (CN)
Filed on Sep. 22, 2022, as Appl. No. 17/950,812.
Claims priority of application No. 202111417800.X (CN), filed on Nov. 26, 2021.
Prior Publication US 2023/0170225 A1, Jun. 1, 2023
Int. Cl. H01L 21/308 (2006.01); H01L 23/544 (2006.01)
CPC H01L 21/3086 (2013.01) [H01L 23/544 (2013.01); H01L 2223/54426 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for forming a fin structure in a fin field effect transistor process, comprising:
step S1: growing a core layer thin film on a substrate;
step S2: performing photolithography and etching for a first time to form a first core layer pattern and a second core layer pattern, the first core layer pattern being used to form fins and the second core layer pattern being used to form a reference layer overlay mark;
step S3: depositing an etching mask layer, the etching mask layer covering tops and side surfaces of the first core layer pattern and the second core layer pattern, and a surface of the substrate;
step S4: etching back the etching mask layer to form sidewalls of the first core layer pattern and sidewalls of the second core layer pattern;
step S5: performing photolithography for a second time to form a first photoresist pattern and a second photoresist pattern, the first photoresist pattern being used to form a planar active area and the second photoresist pattern covering the second core layer pattern;
step S6: removing the first core layer pattern, reserving the sidewalls of the first core layer pattern, and reserving the second photoresist pattern and the first photoresist pattern;
step S7: etching the substrate for a first time to form the fins and the planar active area consisting of a substrate material;
step S8: removing the first photoresist pattern, the second photoresist pattern, and the sidewalls of the second core layer pattern, and reserving the second core layer pattern;
step S9: performing photolithography for a third time to form a third photoresist pattern which covers all of the planar active area and fins outside a fin cut area, and expose the second core layer pattern and the fins inside the fin cut area; and
step S10: etching the substrate for a second time to form at least one reference layer overlay mark and the fin cut area consisting of the substrate material.