US 12,455,505 B2
Method for forming continuous line-end to line-end spaces with spacer assisted lithography-etch-lithography etch processes
Allen Gabor, Katonah, NY (US); and Geng Han, Niskayuna, NY (US)
Assigned to International Business Machines Corporation, Armonk, NY (US)
Filed by International Business Machines Corporation, Armonk, NY (US)
Filed on Mar. 31, 2022, as Appl. No. 17/657,493.
Prior Publication US 2023/0314952 A1, Oct. 5, 2023
Int. Cl. G03F 7/20 (2006.01); H01L 21/027 (2006.01)
CPC G03F 7/2043 (2013.01) [G03F 7/2016 (2013.01); H01L 21/0276 (2013.01)] 19 Claims
OG exemplary drawing
 
1. A method comprising:
forming an initial mandrel structure on a first hardmask layer in a first direction by:
patterning a first resist layer in a starting stack,
applying a litho-etch process to remove a first portion of the first resist layer and first portion of a second hardmask layer to expose a first portion of a mandrel material layer in the starting stack,
removing the first resist layer, and
etching the exposed first portion of the mandrel material layer to form the initial mandrel structure, wherein the initial mandrel structure comprises a section of the mandrel material layer and a section of the second hardmask layer;
forming a first mandrel and a second mandrel with a cut space, where the first mandrel and the second mandrel comprises a tip-to-tip distance across the cut space between the first mandrel and the second mandrel;
forming a spacer layer on the first mandrel and the second mandrel, where the spacer layer fills a portion of the cut space;
forming a next layer on the spacer layer to fill a remaining portion of the cut space;
forming a final resist layer with a first critical dimension (CD) in a first cross-section and a second CD in a second cross-section to form a final resist stack; and
processing the final resist stack to expose a first hardmask layer, where the first hardmask layer comprises a pattern for metal line structures with preserved line-end to line-end spaces corresponding to the cut space.
 
11. A resist stack comprising:
a first mandrel;
a second mandrel;
a cut space positioned between the first mandrel and the second mandrel comprising a tip-to-tip distance across the cut space between the first mandrel and the second mandrel;
a spacer layer formed on first mandrel, the second mandrel, and within a first portion of the cut space;
a next layer formed on the spacer layer, wherein the next layer fills a remaining portion of the cut space;
a resist layer formed on the spacer layer and the next layer comprising:
a first patterned resist section comprising a first critical dimension (CD) in a first cross-section of the resist stack through the first mandrel; and
a second patterned resist section comprising a second CD in a second cross-section of the resist stack through the cut space, wherein the first and second CDs are in a same direction and wherein the first CD is less than the second CD.
 
19. A spacer assisted lithography-etch-lithography-etch (SALELE) method comprising:
forming a first mandrel and a second mandrel using a cut space;
forming a spacer layer on the first mandrel and the second mandrel, where the spacer layer fills a portion of the cut space;
forming a next layer on the spacer layer to fill a remaining portion of the cut space;
forming a final resist layer comprising a first critical dimension (CD) in a first cross-section through a mandrel of the first mandrel and the second mandrel and a second CD in a second cross-section through the cut space, to form a final resist stack, wherein the first and second CDs are in a same direction and wherein the first CD is less than the second CD; and
processing the final resist stack to expose a first hardmask layer, where the first hardmask comprises a pattern for metal line structures with preserved line-end to line-end spaces corresponding to the cut space.