US 11,955,372 B2
Semiconductor storage device
Takehiro Nakai, Yokkaichi Mie (JP); Mizuki Tamura, Nagoya Aichi (JP); and Yumiko Yamashita, Yokkaichi Mie (JP)
Assigned to KIOXIA CORPORATION, Tokyo (JP)
Filed by Kioxia Corporation, Tokyo (JP)
Filed on Aug. 20, 2021, as Appl. No. 17/407,576.
Claims priority of application No. 2020-185963 (JP), filed on Nov. 6, 2020.
Prior Publication US 2022/0148910 A1, May 12, 2022
Int. Cl. H01L 21/762 (2006.01); H01L 27/02 (2006.01); H10B 41/35 (2023.01); H10B 43/35 (2023.01)
CPC H01L 21/76237 (2013.01) [H01L 21/76232 (2013.01); H10B 41/35 (2023.02); H10B 43/35 (2023.02); H01L 27/0207 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A semiconductor storage device, comprising:
a semiconductor substrate;
a plurality of circuit regions formed in the semiconductor substrate; and
an element isolation region formed between one of the plurality of circuit regions and another of the plurality of circuit regions, wherein
the element isolation region has a trench shape that includes a sub-trench formed in a bottom corner portion of the element isolation region,
the element isolation region includes a first insulating film and a second insulating film, the first insulating film covering at least an inner wall of the sub-trench,
the sub-trench having a cross-section,
a radius of curvature of the cross-section of the sub-trench at a tip end point of a recessed portion of the sub-trench is half or less of a width of an opening of the trench in a short-side direction of the trench.