FinFET Fin Capping Layers for Critical Dimension Control
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Solution Overview
Problem
The semiconductor industry faces challenges in controlling the critical dimensions, shapes, and sizes of semiconductor fins in FinFET manufacturing, while also preventing material out-diffusion during processing steps.
Innovation Solution
The method involves forming a protective semiconductor layer over the semiconductor fins, selecting and forming it at varying thicknesses to achieve desired critical dimensions, and using a capping layer to protect the fins from oxidation and material out-diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication methods are used to form semiconductor fins, then manufacturing process simplicity is maintained, but manufacturing precision of fin critical dimensions deteriorates
Solution Approach 1:
The fabrication process is divided into multiple sequential steps: forming mandrels with initial dimensions, depositing a protective layer, selectively removing portions of the protective layer, and performing controlled etching. This segmentation allows precise control over fin critical dimensions by independently optimizing each step rather than relying on a single conventional lithography step.
Solution Approach 2:
A protective layer is deposited over the mandrels before the fin formation etching step. This preliminary action establishes a controlled interface that prevents unwanted material interaction during etching, thereby improving the precision of fin critical dimensions while maintaining process manageability.
2Reliability
If processing steps are performed without protective layers, then process simplicity is maintained, but material out-diffusion occurs during processing
Solution Approach 1:
A protective layer is introduced as an intermediary between the mandrel structure and the processing environment. This layer acts as a barrier that prevents material out-diffusion during subsequent processing steps such as etching and thermal treatments, thereby improving material retention without significantly complicating the overall process flow.
Solution Approach 2:
The protective layer is formed through standard deposition processes and automatically provides the necessary protection against material out-diffusion. The layer serves multiple functions simultaneously: protecting against diffusion, defining etching boundaries, and maintaining structural integrity, thereby achieving reliability enhancement with minimal additional process complexity.
3Manufacturing precision
If uniform protective layer thickness is used, then process simplicity is maintained, but control over fin critical dimensions deteriorates
Solution Approach 1:
The protective layer is selectively removed in specific regions to create non-uniform thickness distribution. By removing portions of the protective layer over certain mandrel regions before etching, the invention achieves local control over fin critical dimensions, allowing different fin widths or profiles in different device regions while maintaining overall process simplicity.
Solution Approach 2:
Instead of uniformly protecting all mandrel regions, the protective layer is partially removed in selected areas. This partial action allows precise control over which regions receive the full protective benefit during etching, thereby enabling fine-tuned control of fin critical dimensions without requiring completely complex selective deposition processes.
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 improves control over fin dimensions and prevents material out-diffusion, enhancing the consistency and effectiveness of subsequent processing steps in FinFET manufacturing.
Implementation Method 1
a protective semiconductor layer may be formed over the semiconductor fins... to prevent or reduce out-diffusion of materials of the semiconductor fins during subsequent processing steps
Implementation Method 2
using a capping layer to protect the fins from oxidation and material out-diffusion
Data Source
AI summary
In an embodiment, a method includes forming a first fin and a second fin within an insulation material over a substrate, the first fin and the second fin includes different materials, the insulation material being interposed between the first fin and the second fin, the first fin having a first width and the second fin having a second width; forming a first capping layer over the first fin; and forming a second capping layer over the second fin, the first capping layer having a first thickness, the second capping layer having a second thickness different from the first thickness.