US 12,482,702 B2
Wet etch process and methods to form air gaps between metal interconnects
Shan Hu, Albany, NY (US); Eric Chih-Fang Liu, Albany, NY (US); Henan Zhang, Albany, NY (US); Sangita Kumari, Albany, NY (US); and Peter Delia, Albany, NY (US)
Assigned to Tokyo Electron Limited, Tokyo (JP)
Filed by Tokyo Electron Limited, Tokyo (JP)
Filed on Sep. 12, 2022, as Appl. No. 17/942,378.
Prior Publication US 2024/0087950 A1, Mar. 14, 2024
Int. Cl. H01L 21/768 (2006.01); H01L 21/311 (2006.01)
CPC H01L 21/7682 (2013.01) [H01L 21/31111 (2013.01)] 24 Claims
OG exemplary drawing
 
1. A method to form air gaps between metal interconnects, the method comprising:
providing a patterned substrate having a plurality of metal interconnects formed within a first dielectric material layer, wherein a critical dimension (CD) between the metal interconnects is small compared to surrounding areas of the patterned substrate;
exposing the patterned substrate to an etch solution to etch the first dielectric material layer and form recesses between the plurality of metal interconnects, wherein said etching removes portions of the first dielectric material layer arranged between the plurality of metal interconnects at a faster etch rate than the first dielectric material layer is removed in the surrounding areas of the patterned substrate;
continuing etching the first dielectric material layer with the etch solution until the recesses formed between the plurality of metal interconnects reach a target recess depth; and
depositing a second dielectric material layer on the patterned substrate, wherein said depositing closes the recesses formed between the plurality of metal interconnects to form air gaps between the plurality of metal interconnects.