Self-Aligned Double Patterning for Precise Dot Patterns
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Solution Overview
Problem
The current cross Self-Aligned Double Patterning (SADP) method faces challenges in forming dot patterns for contact pads in memory devices, as the spacer etch process can damage underlying patterns and multilayer structures with different materials are difficult to fully remove, leading to residue and pattern defects.
Innovation Solution
An additional etch back process and forming additional layer structures with a single material are introduced to ensure that the multilayer structure is simplified, allowing for the complete removal of spacers without damaging the underlying pattern, and enabling a second SADP process to form the desired dot pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the spacer is removed by an etch process after patterning steps, then the photomask is removed, but the underlying pattern defined in previous process is damaged
Solution Approach 1:
A sacrificial layer is introduced as an intermediary between the spacer and the underlying pattern. This sacrificial layer is specifically designed to be etched away selectively, allowing the spacer to be removed without exposing the etch process to the underlying pattern, thus preventing pattern damage while enabling complete spacer removal
2Manufacturing precision
If two self-aligned double patterning processes are conducted to form dot patterns, then the desired dot pattern is formed, but a multilayer structure with different materials is formed which is difficult to fully remove
Solution Approach 1:
The patent applies local quality by making the sacrificial layer have uniform material composition and properties in the regions where it needs to be removed. This uniformity ensures that the etch process can completely remove the sacrificial layer without leaving residues, while the underlying multilayer structure with different materials remains intact for subsequent processing
3Manufacturing precision
If the multilayer structure with different materials is not fully removed, then residue remains on the substrate, but complete removal is difficult due to the multilayer structure
Solution Approach 1:
The sacrificial layer serves as a mediator that simplifies the removal process. By designing the sacrificial layer with specific material properties that differ from the underlying multilayer structure, it can be selectively etched away completely, leaving no residues on the substrate, while the complex multilayer structure remains undisturbed for subsequent processing steps
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 approach reduces residue on the substrate, prevents pattern damage, and facilitates the formation of precise dot patterns by ensuring the multilayer structure is uniformly processed, enhancing the reliability and accuracy of the SADP method.
Implementation Method 1
performing an etch back process so that the top surfaces of line structures and dielectric layer are flush
Implementation Method 2
performing a first etch process with the spacers in the second SADP process as an etch mask to pattern the layer structure, the line structures and the dielectric layer
Data Source
AI summary
A self-aligned double patterning method includes the steps of forming line structures spaced apart from each other in a first direction on a mask layer, forming dielectric layer on the line structures, performing an etch back process so that the top surfaces of the line structures and the dielectric layer are flush, forming layer structure with same material as the line structures on the line structures and the dielectric layer, forming spacers spaced apart from each other in a second direction on the layer structure, and performing an etch process with the spacers as an etch mask to pattern the line structures and the dielectric layer.