Mandrel-Based Metal Line Patterning for High Aspect Ratio Collapse Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor integrated circuits (ICs) scale down, features with high aspect ratios are prone to collapse during fabrication, necessitating a method to prevent this collapse and ensure stable processing and manufacturing.
Innovation Solution
A method involving the formation of trenches in substrates, filled with conducting materials like Al, Cu, or W, and the use of barrier layers and dielectric materials to prevent feature collapse, including the deposition of hard mask layers and the use of chemical mechanical polishing to achieve stable feature dimensions without collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature dimensions are scaled down to increase functional density, then production efficiency is improved and costs are lowered, but the high aspect ratio features become prone to collapse during fabrication
Solution Approach 1:
The method performs preliminary actions by forming a mandrel structure before the final feature, using it as a template to guide subsequent material deposition. The mandrel is removed after transferring the pattern, leaving a stable feature structure that avoids collapse during fabrication processes.
Solution Approach 2:
The mandrel acts as an intermediary structure that facilitates the formation of the final feature. It provides mechanical support during the high aspect ratio feature creation process and is temporarily retained until the pattern is successfully transferred, at which point it is removed.
2Area of moving object
If feature dimensions are scaled down, then functional density increases, but the aspect ratio increases causing features to collapse
Solution Approach 1:
The mandrel is formed in advance with the desired final feature dimensions, providing a pre-defined template that guides the deposition of conformal layers. This preliminary structure ensures that the final feature achieves the target small dimensions without requiring direct patterning of high aspect ratio structures.
Solution Approach 2:
The final feature is formed by depositing conformal layers around the mandrel, effectively nesting the feature structure within the mandrel's dimensional envelope. The conformal deposition process builds the feature layer by layer around the mandrel template, ensuring uniform thickness and stable geometry.
3Manufacturing precision
If high aspect ratio features are formed to achieve small dimensions, then scaling benefits are realized, but pattern collapse occurs during fabrication
Solution Approach 1:
The mandrel provides a pre-formed template that defines the final feature dimensions before any conformal deposition occurs. This preliminary structure eliminates the need to directly pattern high aspect ratio features, as the mandrel's simpler geometry is formed first using standard lithography and etching processes.
Solution Approach 2:
The method changes the manufacturing approach by transitioning from direct patterning of high aspect ratio features to conformal deposition around a mandrel template. This parameter change in the fabrication process enables precise dimensional control while avoiding the collapse issues associated with direct high aspect ratio feature formation.
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
This method allows for the scaling down of feature dimensions to as low as 10 nm without pattern or feature collapse, maintaining production efficiency and reducing manufacturing costs by stabilizing high aspect ratio features during IC fabrication.
Implementation Method 1
a first barrier layer over the substrate and surrounding sidewalls of the trench
Implementation Method 2
the use of chemical mechanical polishing to achieve stable feature dimensions without collapse
Implementation Method 3
filled with conducting materials like Al, Cu, or W, and the use of barrier layers and dielectric materials to prevent feature collapse
Data Source
AI summary
Methods are disclosed herein for forming conductive patterns having small pitches. An exemplary method includes forming a metal line in a first dielectric layer. The metal line has a first dimension along a first direction and a second dimension along a second direction that is different than the first direction. The method includes forming a patterned mask layer having an opening that exposes a portion of the metal line along an entirety of the second dimension and etching the portion of the metal line exposed by the opening of the patterned mask layer until reaching the first dielectric layer. The metal line is thus separated into a first metal feature and a second metal feature. After removing the patterned mask layer, a barrier layer is deposited over exposed surfaces of the first metal feature and the second metal feature and a second dielectric layer is deposited over the barrier layer.