Multi-patterning Metal Lines with Variable Widths
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Solution Overview
Problem
Current multi-patterning techniques for semiconductor integrated circuits, such as SID SADP, face limitations in forming wider wires within arrays of uniform width metal lines, requiring complex alignment and affecting lithography fidelity of adjacent features.
Innovation Solution
A method involving the formation of elongated sacrificial features and spacers on a substrate, followed by the use of an unblock mask to selectively etch wider trenches in the hardmask layer, allowing for the creation of metal lines with varying widths, including wider lines within an array of minimum width lines, without the need for additional cut masks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional SID SADP techniques are used to form uniform width metal lines, then manufacturing precision for minimum width lines is improved, but adaptability to form wider wires is limited
Solution Approach 1:
The patent applies local quality by making different regions of the hardmask layer have different properties - most regions maintain the standard etch hardmask properties for minimum width lines, while selected regions are modified to be removable to create wider trenches. This allows the same base structure to serve multiple functions: maintaining precision for standard lines while enabling variability for wider power/clock lines.
Solution Approach 2:
The unblock mask is formed in advance before the final etch process, allowing selective removal of hardmask material in predetermined locations. This preliminary action creates the wider trench regions ahead of time, so when the etch process occurs, both minimum width and wider lines are formed simultaneously in a single step, maintaining precision while enabling adaptability.
2Adaptability or versatility
If wider mandrel shapes are used to create wider wires, then adaptability to form different wire widths is improved, but lithography fidelity of adjacent 1X-width features deteriorates
Solution Approach 1:
The patent segments the hardmask removal process by using the unblock mask to selectively remove hardmask material only in specific regions where wider lines are needed. The sacrificial mandrels remain intact and continue to serve as lithography templates for adjacent minimum width lines, preventing any degradation of lithography fidelity while still enabling wider line formation in the unmasked regions.
Solution Approach 2:
The patent extracts the hardmask material selectively from regions where wider lines are desired, while leaving the hardmask intact in regions where minimum width lines will be formed. This extraction is achieved through the unblock mask pattern, which removes hardmask only in predetermined locations, thereby creating wider trenches without affecting the lithography fidelity of adjacent features.
3Adaptability or versatility
If a single wide wire is inserted in an array of uniform wires, then adaptability is improved, but device complexity increases due to alignment requirements
Solution Approach 1:
The patent merges the formation of minimum width lines and wider lines into a single integrated process. The unblock mask pattern is designed to work in conjunction with the sacrificial mandrel array, allowing both types of lines to be formed simultaneously in one etch step. This eliminates the need for separate alignment steps and complex coordination between different patterning operations, reducing device complexity while maintaining adaptability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables the fabrication of metal lines with different widths, including wider lines, within the BEOL structure, improving the flexibility and fidelity of the patterning process while maintaining the integrity of adjacent features.
Implementation Method 1
patterning the hardmask layer using the pattern of elongated sacrificial features as an etch mask to form an etch hardmask
Implementation Method 2
Multi-patterning techniques for fabricating an array of metal lines with different widths
Data Source
AI summary
Multi-patterning methods are provided for use in fabricating an array of metal lines comprising metal lines with different widths. For example, patterning methods implement spacer-is-dielectric (SID)-based self-aligned double patterning (SADP) methods for fabricating an array of metal lines comprising elongated metal lines with different widths, wherein an “unblock” mask is utilized as part of the process flow to overlap mandrel assigned and non-mandrel assigned features in a given SADP pattern to define regions to unblock a metal fill (remove dielectric material between wires) in a dielectric layer between defined metal lines of an a SADP pattern thus enabling the formation of wide metal lines within any region of a pattern of elongated metal lines formed with a minimum feature width.