Double Patterning Layout With Conformal Liner for Pitch Walking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing double patterning methods in semiconductor manufacturing suffer from pitch walking, leading to edge placement errors due to variations in mandrel and spacer widths, which are not controlled effectively, limiting the ability to achieve uniform pitch and pattern transfer.
Innovation Solution
A method involving self-aligned double patterning (SADP) with a litho-etch-litho-etch (LELE) approach, including the formation of spacers and blocks to control pitch variations by adjusting the widths of trenches and using conformal liners to reduce edge placement errors, ensuring uniformity in pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple patterning is used to achieve sub-10 nm half-pitch, then resolution limit is overcome, but pitch walking and edge placement errors occur
Solution Approach 1:
The patent segments the patterning process into multiple distinct steps (first lithography to form mandrels, spacer formation, second lithography to form blocks, selective removal). This segmentation allows each step to be optimized independently, with the spacer width and block dimensions carefully controlled to compensate for variations in mandrel width, thereby reducing pitch walking and edge placement errors in the final pattern
Solution Approach 2:
The patent changes physical parameters throughout the process: using different materials for mandrels and spacers with distinct etch selectivities, controlling spacer width to be a specific fraction of mandrel width, and adjusting block dimensions. These parameter changes enable precise control over the final pitch and reduce sensitivity to mandrel width variations
2Productivity
If feature size is reduced to double component packing density, then cost is reduced, but lithography resolution requirement increases
Solution Approach 1:
The patent transitions from two-dimensional lithographic patterning to three-dimensional structure formation using self-aligned spacers and blocks. By utilizing the vertical dimension for spacer deposition and the controlled removal of sacrificial mandrels, the method achieves sub-lithographic pitch multiplication, effectively doubling component packing density without requiring proportionally smaller lithography features
Solution Approach 2:
The spacer structures serve a dual function: they define the final pattern geometry and simultaneously act as self-aligned masks for subsequent etching steps. This self-service approach eliminates the need for additional alignment steps and reduces cumulative alignment errors, enabling higher density patterning with existing lithography capabilities
3Manufacturing precision
If mandrel and spacer widths are not controlled effectively, then pitch walking occurs, but controlling them increases process complexity
Solution Approach 1:
The patent incorporates feedback mechanisms through selective measurement and adjustment: mandrel widths are measured and used to compute target spacer widths, which are then adjusted based on actual mandrel dimensions. This feedback loop compensates for process variations and ensures uniform pitch across wafers and lots, reducing pitch walking without requiring overly complex real-time control systems
Solution Approach 2:
The patent performs preliminary actions by pre-defining spacer width as a function of mandrel width before the actual patterning process. Target spacer dimensions are calculated in advance based on desired pitch specifications and expected mandrel width ranges, allowing process engineers to pre-optimize the process window and reduce sensitivity to variations during production
Data Source
AI summary
A method of forming a semiconductor device includes forming, over a hardmask layer and an underlying layer of a substrate, a pattern of first trenches between adjacent template lines, each of the first trenches exposing a portion of the hardmask layer, and each of the template lines including a mandrel and spacers on sidewalls of the mandrel; forming a pattern of first blocks over the pattern of the first trenches and the template lines, the first blocks dividing the first trenches to form a pattern of first stencil trenches; transferring the pattern of first stencil trenches to the hardmask layer to form a pattern of first hardmask trenches, each of the first hardmask trenches exposing a portion of the underlying layer; forming a first fill layer filling the first hardmask trenches and exposing the mandrels; selectively removing the mandrels to form second trenches, each of the second trenches exposing a portion of the hardmask layer; and forming a conformal liner in the second trenches and over a surface of the spacers, a surface of the first blocks, and a surface of the first fill layer to form third trenches.