Self-Aligned Double Patterning for Line Wiggle Reduction
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Solution Overview
Problem
The increasing down-scaling of integrated circuits leads to poor wiggling resistance during pattern transfer to amorphous silicon substrates, resulting in pattern defects and line wiggling, which can cause metal pattern lines to break and fail.
Innovation Solution
A method is developed to reduce the height-to-width aspect ratio of pattern layers in the lithography process, using a self-aligned double patterning technique that involves forming a tri-layer structure with a patterned top layer, transferring the pattern to subsequent layers, and widening the openings to achieve straighter metal lines with reduced wiggle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high aspect ratio stacking of layers is used in photo patterning techniques, then integration density is improved, but line wiggling resistance deteriorates
Solution Approach 1:
The mask layer is divided into multiple segments (first mask layer and second mask layer) stacked vertically. Each segment performs part of the patterning function, allowing the overall high aspect ratio structure to be achieved while each individual segment maintains better structural stability and reduced line wiggling during etching.
Solution Approach 2:
The solution transitions from a single-layer mask approach to a multi-layer stacked mask structure, adding the vertical dimension to the mask layer configuration. This dimensional change allows distribution of the patterning function across multiple layers, improving both integration density and line wiggling resistance.
2Manufacturing precision
If high aspect ratio mask layers are used, then pattern transfer capability is improved, but pattern defects increase due to line wiggling
Solution Approach 1:
The mask layer is segmented into multiple stacked layers, where each layer contributes to the overall pattern transfer. This segmentation reduces the aspect ratio burden on each individual layer, minimizing line wiggling and associated pattern defects while maintaining effective pattern transfer capability.
Solution Approach 2:
The invention changes the structural parameters of the mask layer by creating a stacked configuration with multiple layers of different thicknesses. This parameter change optimizes the aspect ratio distribution, reducing line wiggling and pattern defects while preserving pattern transfer effectiveness.
3Device complexity
If single layer mask is used, then process complexity is reduced, but line wiggling occurs during etching
Solution Approach 1:
The mask structure is segmented into multiple stacked layers, which increases structural complexity but resolves the line wiggling issue. The segmentation allows each layer to be optimized independently, improving etching performance and line straightness.
Solution Approach 2:
The stacked mask structure functions as a composite structure where multiple layers with different properties work together. This composite approach provides both the necessary pattern definition capability and improved resistance to line wiggling during the etching process.
Data Source
AI summary
A method for reducing wiggling in a line includes forming a first patterning layer over a metal feature and depositing a first mask layer over the first patterning layer. The first mask layer is patterned to form a first set of one or more openings therein and then thinned. The pattern of the first mask layer is transferred to the first patterning layer to form a second set of one or more openings therein. The first patterning layer is etched to widen the second set of one or more openings. The first patterning layer may be comprised of silicon or an oxide material. The openings in the first patterning layer may be widened while a mask layer is over the first patterning layer.