Method for forming continuous line-end to line-end spaces with spacer assisted lithography-etch-lithography etch processes
AssigneeInternational Business Machines Corporation
InventorsAllen Gabor, Geng Han
Life of this patent
Estimating the term…
Abstract
Method and apparatus for improved and efficient spacer assisted lithography-etch-lithography etch (SALELE) processes that utilize a spin-on-material layer, where the spin-on-material layer fills gaps between spacers to protect line-end to line-end spaces created by a cut shape. The method and structures also include a final resist layer with varying critical dimensions (CDs). The use of the spin-on-material enables back end of line (BEOL) metal designs with continuous line-end to line-end spacing above a minimum that can be patterned with a cut mask and spacer only process.
Claims19
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.
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.
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.
Dependencies are inferred from the claim text.