Anti-Spacer Resist Patterning for Sub-Pitch Semiconductor Features
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Solution Overview
Problem
Conventional semiconductor processing techniques, such as photolithography, face limitations in reducing feature size due to minimum pitch constraints, leading to reliability issues and device failures, particularly with pitch doubling methods that involve complex processes and dishing problems in metal features.
Innovation Solution
The anti-spacer technique is employed, involving the formation of a first and second photosensitive resist material over a substrate, where a chemically active species diffuses into the first resist material to deprotect specific portions, allowing for the formation of smaller features by controlling the solubility and subsequent removal of resist materials to pattern metal lines and pads efficiently, thereby overcoming the resolution limits of conventional photolithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional photolithography is used, then manufacturing process is simple, but feature size cannot be reduced below minimum pitch
Solution Approach 1:
The manufacturing process is divided into multiple stages: forming mandrels at a first pitch, depositing spacers, selectively removing materials, and forming final features at a reduced pitch. This segmentation allows achieving sub-photolithography pitch features while managing process complexity through systematic breakdown of steps
Solution Approach 2:
The patent introduces a vertical dimension by forming three-dimensional structures (mandrels, spacers, and layered materials) that extend beyond the two-dimensional photolithography plane. This enables pitch multiplication by utilizing vertical spacing and layering to create horizontal feature patterns at reduced pitches
2Length of moving object
If pitch doubling technique is used, then feature size is reduced, but process complexity increases and dishing occurs in metal features
Solution Approach 1:
The method performs preliminary actions by forming mandrels and spacers in advance with controlled dimensions and positions. The spacer material is deposited and patterned before final metal feature formation, establishing a template that guides subsequent processing and reduces the number of iterative adjustment steps
Solution Approach 2:
The patent controls and changes multiple parameters including spacer thickness, mandrel dimensions, etch selectivity, and deposition conditions to optimize the pitch multiplication process. By precisely controlling these parameters, the process achieves reduced pitch while minimizing dishing through optimized material removal and deposition conditions
3Manufacturing precision
If abrasive removal process is used on metal material, then excess metal is removed, but dishing occurs in central portions of metal features
Solution Approach 1:
The patent employs controlled partial removal of metal material through the spacer pattern, where metal is deposited and then selectively removed only in regions defined by the spacer geometry. This partial action approach, combined with optimized removal conditions, prevents excessive material removal that causes dishing while achieving the desired pattern definition
Solution Approach 2:
The method replaces purely mechanical abrasive removal with a chemically-assisted process where spacer-defined patterns guide selective metal removal. The spacer structure acts as a protective mask during removal, distributing stress and material removal more uniformly to prevent dishing in large metal features
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 enables the formation of complex, two-dimensional patterns at sizes below conventional photolithography limits, reducing manufacturing complexity and avoiding dishing issues, while ensuring uniformity and reliability of semiconductor device features.
Implementation Method 1
a chemically active species diffuses into the first resist material to deprotect specific portions
Implementation Method 2
portions of the first and second photosensitive resist materials are exposed to radiation
Data Source
AI summary
Methods of forming a pattern in a semiconductor device structure include deprotecting an outer portion of a first photosensitive resist material, forming a second photosensitive resist material, exposing portions of the first and second photosensitive resist materials to radiation, and removing the deprotected outer portion of the first photosensitive resist material and the exposed portions of the first and second photosensitive resist materials. Additional methods include forming a first resist material over a substrate to include a first portion and a relatively thicker second portion, deprotecting substantially the entire first portion and an outer portion of the second portion while leaving an inner portion of the second portion protected, and forming a second resist material over the substrate. A portion of the second resist material is exposed to radiation, and deprotected and exposed portions of the first and second resist materials are removed.