Multi-Patterning Photomask Stitching for IC Fabrication
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Solution Overview
Problem
Conventional multi-patterning processes for fabricating integrated circuits require a large number of photomasks, increasing costs and reducing process efficiency due to the need for separate masks for metal lines and interconnecting vias/contacts.
Innovation Solution
Decomposing the master pattern layout into sub-patterns that include overlapping line feature patterns for both metal lines and interconnecting vias/contacts, allowing for the generation of fewer photomasks by integrating the details of both into each sub-pattern, thereby reducing the total number of masks required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional multi-patterning processes use separate photomasks for metal lines and interconnecting vias/contacts, then manufacturing precision is maintained, but the number of photomasks increases leading to higher costs and reduced process efficiency
Solution Approach 1:
The patent combines the patterning of metal lines and interconnecting vias/contacts into a single photomask by using overlapping line feature patterns. The first and second line feature patterns from different sub-patterns overlap to define the stitch location for interconnecting vias/contacts, eliminating the need for separate photomasks for these features.
Solution Approach 2:
Each photomask in the invention serves multiple functions by containing both metal line patterns and interconnecting via/contact patterns. The same photomask is used to define both the metal line geometry and the locations of interconnecting structures through the overlapping pattern approach.
2Manufacturing precision
If conventional multi-patterning processes decompose master pattern layout into separate sub-patterns for metal lines and vias/contacts, then manufacturing precision is maintained, but process efficiency decreases due to increased number of photomasks
Solution Approach 1:
The invention merges the decomposition of metal line patterns and via/contact patterns into unified sub-patterns. Each sub-pattern contains both metal line features and interconnecting structure features that overlap to define stitch locations, reducing the total number of photomasks required.
Solution Approach 2:
The overlapping line feature patterns are designed in advance during mask generation to pre-defines the stitch locations for interconnecting vias/contacts. This preliminary integration of via/contact definition into the line pattern decomposition eliminates subsequent separate patterning steps.
3Manufacturing precision
If separate photomasks are used for metal lines and interconnecting vias/contacts, then pattern fidelity is maintained, but cost efficiency decreases due to increased mask quantity
Solution Approach 1:
The patent merges the definition of metal lines and interconnecting vias/contacts into single photomasks through overlapping line feature patterns. This consolidation maintains pattern fidelity while reducing the total number of photomasks, thereby improving cost efficiency.
Data Source
AI summary
Methods for fabricating integrated circuits are provided. One method includes decomposing a master pattern layout for a semiconductor device layer that includes a target metal line with a target interconnecting via/contact into a first sub-pattern and a second sub-pattern. The target metal line is decomposed into a first line feature pattern that is part of the first sub-pattern and a second line feature pattern that is part of the second sub-pattern such that the first and second line feature patterns have overlapping portions defining a stitch that corresponds to the target interconnecting via/contact. A first photomask is generated that corresponds to the first sub-pattern. A second photomask is generated that corresponds to the second sub-pattern.