US 11,810,786 B2
Method for fabricating semiconductor device
Po-Wen Su, Kaohsiung (TW); and Cheng-Han Lu, Chiayi (TW)
Assigned to UNITED MICROELECTRONICS CORP., Hsinchu (TW)
Filed by UNITED MICROELECTRONICS CORP., Hsinchu (TW)
Filed on Jul. 27, 2021, as Appl. No. 17/385,969.
Claims priority of application No. 202110724797.X (CN), filed on Jun. 29, 2021.
Prior Publication US 2022/0415647 A1, Dec. 29, 2022
Int. Cl. H01L 21/027 (2006.01); H01L 21/768 (2006.01); H01L 21/3213 (2006.01); H01L 21/033 (2006.01); H01L 21/311 (2006.01); H01L 21/308 (2006.01)
CPC H01L 21/0274 (2013.01) [H01L 21/0337 (2013.01); H01L 21/3086 (2013.01); H01L 21/31144 (2013.01); H01L 21/32139 (2013.01); H01L 21/76816 (2013.01); H01L 21/76892 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A method for fabricating a semiconductor device, comprising:
forming a patterned mask layer including a plurality of standing walls and at least one covering part on a surface of a semiconductor substrate, wherein at least two adjacent ones of the plurality of standing walls define at least one first opening exposing a portion of the surface, and the at least one covering part blankets over the surface;
forming a first patterned photoresist layer to at least partially cover the at least one covering part;
performing a first etching process, using a combination of the patterned mask layer and the first patterned photoresist layer as an etching mask, to form at least one first trench in the substrate, passing through the surface and aligning with the at least one first opening;
removing a portion of the patterned mask layer to form at least one second opening exposing another portion of the surface;
performing a second etching process, using a combination of a remaining portion of the patterned mask layer and the first patterned photoresist layer as an etching mask, to form at least one second trench in the semiconductor substrate and define an active area on the surface, wherein the at least one first trench has a depth greater than that of the at least one second trench.