Self-Aligned Fin Cut Using Sacrificial Gate Etch Mask
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional fin cut processes for FinFET semiconductor devices face challenges in precision and accuracy due to patterning limitations and alignment issues in photolithography, leading to imprecise alignment and potential damage during fin cut patterning.
Innovation Solution
A self-aligned fin cut process using a sacrificial gate or epitaxially-formed source/drain region as an etch mask, instead of a lithographically-defined fin cut mask, to remove unwanted fin portions, with a dielectric fill layer aligned with the gate or source/drain edges to define the fin cut region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a lithographically-defined fin cut mask is used, then the fin cut region can be defined, but alignment imprecision and corner rounding damage fin portions
Solution Approach 1:
The sacrificial gate structure is formed beforehand to serve as the etch mask for defining the fin cut region. This preliminary structure provides precise alignment references that eliminate corner rounding damage to fin portions, as the gate structure itself defines the cut boundaries without requiring additional lithographic patterning steps that cause alignment errors.
Solution Approach 2:
A sacrificial gate structure is introduced as an intermediary element that serves dual purposes: it acts as a placeholder during fabrication and simultaneously serves as the precise etch mask for fin cutting. This intermediary structure eliminates the need for separate fin cut masks and their associated alignment problems, providing accurate fin portion definition without damage.
2Manufacturing precision
If photolithography is used for fin cut patterning, then the fin cut region can be defined, but alignment tolerances are compromised at advanced nodes
Solution Approach 1:
The gate structure serves itself as the etch mask for fin cutting, eliminating the need for separate alignment-critical lithographic steps. The gate structure's own geometry defines the fin cut boundaries with high precision, leveraging the gate structure's inherent alignment accuracy to the fin array rather than requiring additional mask alignment tolerances.
3Manufacturing precision
If a sacrificial gate is used as etch mask, then fin cut accuracy is improved, but process complexity increases
Solution Approach 1:
The sacrificial gate structure performs multiple functions: it serves as a structural element during fabrication, acts as the etch mask for precise fin cutting, and can be removed or retained based on device requirements. This multi-functionality eliminates the need for separate fin cut masks and reduces overall process complexity despite the additional sacrificial gate formation 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 enhances the accuracy and precision of fin cutting, reducing damage to intended fin portions and enabling the formation of hybrid, tapered FinFET structures with improved electrostatic control and device performance.
Implementation Method 1
selective-etching techniques
Implementation Method 2
a dielectric fill layer is formed within the fin cut openings
Implementation Method 3
epitaxially-formed source/drain region
Data Source
AI summary
In a self-aligned fin cut process for fabricating integrated circuits, a sacrificial gate or an epitaxially-formed source/drain region is used as an etch mask in conjunction with a fin cut etch step to remove unwanted portions of the fins. The process eliminates use of a lithographically-defined etch mask to cut the fins, which enables precise and accurate alignment of the fin cut.