Selective Fin Removal for Small Pitch FinFET STI Regions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional photolithography and etching techniques face challenges in fabricating shallow trench isolation (STI) regions in fin field effect transistors (FinFETs) with small fin pitch, leading to damage or removal of multiple fins due to limitations in pattern transfer fidelity and minimal pattern pitch.
Innovation Solution
A method involving forming fins and caps on a semiconductor substrate, followed by creating an isolation layer and patterning layer, selectively removing caps and fins to form fin and isolation trenches, and filling these trenches with insulating material to create an isolation region, allowing for improved overlay and pattern fidelity without damaging adjacent fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional photolithography and etching techniques are used to fabricate STI regions in FinFETs with small fin pitch, then the process is simple and well-established, but pattern transfer fidelity deteriorates and multiple fins are damaged or removed
Solution Approach 1:
The patent segments the STI formation process into distinct stages: forming isolation trenches between fins first, then selectively removing individual fins. This segmentation allows each step to be optimized independently, improving pattern transfer fidelity by avoiding the need to pattern multiple adjacent fins simultaneously with a single photolithography step.
Solution Approach 2:
The patent performs preliminary action by forming the isolation trenches and filling them with insulating material before selectively removing individual fins. This preliminary structuring creates a template that guides subsequent selective fin removal, enabling precise pattern transfer without damaging adjacent fins that would occur in conventional simultaneous patterning.
2Manufacturing precision
If conventional etching is used to remove multiple fins for STI formation, then the process is straightforward, but fin pitch limitations are encountered and adjacent fins are damaged
Solution Approach 1:
The patent separates the trench formation from fin removal operations. Isolation trenches are formed first with precise spacing, then individual fins are selectively removed later. This segmentation enables precise isolation trench positioning independent of fin pitch constraints, allowing smaller fin pitches without cross-contamination between adjacent structures.
Solution Approach 2:
The patent introduces an intermediary structure (the isolation trench filled with insulating material) that acts as a protective barrier and alignment reference. This intermediary enables precise fin removal by providing physical separation and etch selectivity, preventing damage to adjacent fins even at small pitch dimensions.
3Productivity
If selective fin removal is performed to form isolation trenches, then device density improves, but process selectivity requirements increase
Solution Approach 1:
The patent applies local quality by using selective etching processes that target specific fin regions based on local differences in fin structure, cap presence, or prior trench formation. This localized selectivity enables individual fin removal for STI formation while preserving adjacent fins, increasing device density without requiring global process changes.
Solution Approach 2:
The patent utilizes parameter changes in etch selectivity by adjusting etch chemistry, power, and gas flow to achieve differential etching rates between fins to be removed and adjacent fins to be preserved. These parameter optimizations enable high selectivity removal of individual fins, improving device density while managing process complexity through controlled parameter variation.
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 enables the formation of isolation trenches with enhanced precision and fidelity, allowing for the removal of a single fin while maintaining isolation between devices, thereby improving device density and preventing current leakage.
Implementation Method 1
removing one of the plurality of fins from a fin field effect transistor (FINFET) device using a selective etching process to form a fin trench
Data Source
AI summary
The present invention relates generally to semiconductor devices, and particularly to fabricating a shallow trench isolation (STI) region in fin field effect transistors (FinFETs) having a small fin pitch. According to one embodiment, a method of using selective etching techniques to remove a single fin to form a fin trench and to form an isolation trench having a width approximately equal to a width of the single fin below the removed fin is disclosed. The fin trench and the isolation trench may be filled with isolation material to form an isolation region.