Recessed Spacer Protective Caps for Mandrel Pull Damage Reduction
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Solution Overview
Problem
The mandrel pull process in semiconductor device manufacturing often results in spacer damage, leading to defects and failures in microelectronic devices, particularly at advanced nodes like 7 nanometer and 5 nanometer processes, due to the difficulty in achieving high selectivity and local damage during the self-aligned double/multiple patterning and sidewall image transfer processes.
Innovation Solution
The process involves forming spacers recessed relative to mandrels, depositing protective caps over the spacers, and selectively etching to remove the mandrels while protecting the spacers, which reduces spacer damage and allows for improved pattern transfer to underlying layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If plasma etch is used for mandrel pull with high selectivity requirement, then mandrel removal efficiency is improved, but spacer damage and local defects increase
Solution Approach 1:
A protective cap layer is deposited over the spacers before the mandrel pull etch process. This intermediary layer protects the spacers from direct exposure to the harsh etch plasma, reducing spacer damage and local defects while still allowing efficient mandrel removal through selective etching of the mandrels beneath the protective cap.
Solution Approach 2:
The protective cap is formed in advance before the mandrel pull process. This preliminary action prepares the structure to withstand the subsequent high-selectivity plasma etch, preventing spacer damage before it occurs rather than attempting to address it during or after the etch process.
2Manufacturing precision
If high selectivity etch is used for mandrel pull, then pattern transfer precision is improved, but process difficulty and complexity increase
Solution Approach 1:
The protective cap serves as a mediator that simplifies the etch process. Instead of requiring extremely high selectivity between mandrel and spacer materials, the protective cap decouples these requirements, allowing use of more robust and better-understood etch chemistries with reduced process complexity.
Solution Approach 2:
The process is segmented into distinct steps: protective cap formation, mandrel pull etch, and cap removal. This segmentation allows each step to be optimized independently, reducing overall process complexity while maintaining high pattern transfer precision through controlled selective etching.
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 or eliminates spacer damage and line breaks, enabling more reliable pattern transfer and meeting the stringent requirements of advanced semiconductor processes by controlling etch selectivity and cap coverage, thus enhancing the integrity of microelectronic devices.
Implementation Method 1
For mandrel pull, plasma etch is typically used where a highly anisotropic and highly selective etch is required
Implementation Method 2
forming protective caps over the spacers while exposing top surfaces of the mandrels
Data Source
AI summary
Embodiments are disclosed for processing microelectronic workpieces having patterned structures to improve mandrel pull from spacers for multi-color patterning. The disclosed embodiments form patterned structures on a substrate including mandrels, form spacers adjacent the mandrels that are recessed such that a height of the spacers is less than the height of the mandrels, form protective caps over the spacers while exposing top surfaces of the mandrels, and remove the mandrels to leave a spacer pattern with cap protection. The remaining spacer pattern can then be transferred to underlying layers in additional process steps. The recessing of the spacers and formation of the protective caps tends to reduce or eliminate spacer damage suffered by prior solutions during mandrel pull from spacers for multi-color patterning.