US 12,432,903 B2
Semiconductor structure and method for fabricating same
Yong Lu, Hefei (CN); Zhicheng Shi, Hefei (CN); Xinran Liu, Hefei (CN); and Ruiqi Zhang, Hefei (CN)
Assigned to CHANGXIN MEMORY TECHNOLOGIES, INC., Hefei (CN)
Filed by CHANGXIN MEMORY TECHNOLOGIES, INC., Hefei (CN)
Filed on Jan. 10, 2023, as Appl. No. 18/152,168.
Application 18/152,168 is a continuation of application No. PCT/CN2022/082211, filed on Mar. 22, 2022.
Claims priority of application No. 202210029907.5 (CN), filed on Jan. 12, 2022.
Prior Publication US 2023/0225104 A1, Jul. 13, 2023
Int. Cl. H01L 21/762 (2006.01); H01L 21/764 (2006.01); H01L 21/768 (2006.01); H10B 12/00 (2023.01); H10D 62/10 (2025.01); H10D 64/66 (2025.01)
CPC H10B 12/053 (2023.02) [H01L 21/76289 (2013.01); H01L 21/764 (2013.01); H01L 21/7682 (2013.01); H10B 12/34 (2023.02); H10D 62/116 (2025.01); H10D 64/679 (2025.01); H01L 2221/1042 (2013.01); H01L 2221/1063 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A method for fabricating a semiconductor structure, comprising:
providing a substrate, wherein a trench is formed in the substrate;
sequentially forming a dielectric layer and a conductive layer in the trench, wherein the dielectric layer is positioned between the conductive layer and an inner wall of the trench; and the conductive layer comprises a first conductive layer and a second conductive layer positioned on the first conductive layer, a top of the dielectric layer being lower than a top of the first conductive layer, a projection area of a bottom of the second conductive layer within the trench being greater than a projection area of the top of the first conductive layer within the trench, and a work function of the first conductive layer being greater than a work function of the second conductive layer; and
forming an isolation layer on the conductive layer, wherein the isolation layer, the conductive layer, the dielectric layer, and a side wall of the trench define a void;
wherein the void comprises a first void and a second void; and the sequentially forming the dielectric layer and the conductive layer in the trench comprises:
sequentially forming the dielectric layer and the first conductive layer in the trench; and
forming the second conductive layer on an upper surface of the first conductive layer, wherein the first void is provided between the second conductive layer and the side wall of the trench, and the second void is provided between the first conductive layer and the side wall of the trench;
wherein the forming the second conductive layer on the upper surface of the first conductive layer comprises:
forming a first sacrificial layer on the side wall of the trench, wherein the first sacrificial layer is positioned above the dielectric layer, and a gap is provided between portions of the first sacrificial layer on opposite side walls of the trench;
forming the second conductive layer in the gap, wherein the second conductive layer fills up the gap, and the second conductive layer is in contact with the first conductive layer; and
removing the first sacrificial layer to form the first void;
wherein before forming the first sacrificial layer on the side wall of the trench, the method further comprises:
forming a second sacrificial layer on an upper surface of the dielectric layer, wherein the second sacrificial layer surrounds the first conductive layer, the first conductive layer is exposed at a top of the second sacrificial layer, and a bottom of the first sacrificial layer is flush with the top of the second sacrificial layer;
wherein before forming the isolation layer on the conductive layer, the method further comprises:
removing the second sacrificial layer to form the second void.