US 12,142,520 B2
Middle-of-line interconnect structure having air gap and method of fabrication thereof
Yi-Nien Su, Hsinchu (TW); and Jyu-Horng Shieh, Hsin-Chu (TW)
Assigned to TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD, Hsinchu (TW)
Filed by Taiwan Semiconductor Manufacturing Company, Ltd., Hsin-Chu (TW)
Filed on Aug. 10, 2022, as Appl. No. 17/884,714.
Application 17/884,714 is a continuation of application No. 17/147,177, filed on Jan. 12, 2021, granted, now 11,710,657.
Claims priority of provisional application 63/084,792, filed on Sep. 29, 2020.
Prior Publication US 2022/0384243 A1, Dec. 1, 2022
Int. Cl. H01L 21/768 (2006.01); H01L 21/3213 (2006.01); H01L 23/522 (2006.01); H01L 23/532 (2006.01); H01L 23/535 (2006.01)
CPC H01L 21/7682 (2013.01) [H01L 21/32133 (2013.01); H01L 21/32139 (2013.01); H01L 21/7685 (2013.01); H01L 21/76895 (2013.01); H01L 23/5226 (2013.01); H01L 23/53252 (2013.01); H01L 23/53257 (2013.01); H01L 23/5329 (2013.01); H01L 23/535 (2013.01)] 20 Claims
OG exemplary drawing
 
16. A method comprising:
forming a device-level contact in a first dielectric layer;
depositing a ruthenium layer over the device-level contact and the first dielectric layer;
depositing a multilayer hard mask over the ruthenium layer;
using a top portion of the multilayer hard mask to form an oxide feature, wherein the oxide feature is disposed over the device-level contact and the top portion of the multilayer hard mask is removed when forming the oxide feature;
patterning a bottom portion of the multilayer hard mask and the ruthenium layer to form a contact structure over the device-level contact, wherein the oxide feature is used to pattern the bottom portion of the multilayer hard mask, the oxide feature is removed when patterning the bottom portion of the multilayer hard mask and the ruthenium layer, and the contact structure includes a ruthenium contact layer, a first mask layer over the ruthenium contact layer, and a second mask layer over the first mask layer;
depositing an amorphous material layer that wraps the contact structure;
depositing a second dielectric layer over the amorphous material layer, the first dielectric layer, and the contact structure;
planarizing the second dielectric layer, wherein the planarizing removes the second mask layer of the contact structure and exposes the first mask layer of the contact structure;
after removing the first mask layer of the contact structure, removing the amorphous material layer from along sidewalls of the contact structure;
depositing an etch stop layer over the second dielectric layer and the ruthenium contact layer of the contact structure, wherein the etch stop layer partially fills a recess formed by the removing of the first mask layer of the contact structure;
forming a third dielectric layer over the etch stop layer; and
forming a metal contact that extends through the third dielectric layer, the etch stop layer, and the second dielectric layer to the ruthenium contact layer.