Straight Fin Growth via Spacer Defined Epitaxy
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Solution Overview
Problem
Current semiconductor manufacturing processes result in fin bending and tapered profiles for 7 nanometer (nm) fins, with no effective method to create straight fins of such narrow width.
Innovation Solution
The process involves forming STI regions separated by silicon regions with a silicon nitride hardmask, planarizing, removing the hardmask to create recesses, forming a conformal spacer layer, removing horizontal spacer portions, and epitaxially growing silicon to form straight fins, skipping the STI deglaze process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If current STI oxide fill and anneal processes are used, then fins can be formed, but fin bending occurs during the process
Solution Approach 1:
The patent applies preliminary action by performing STI planarization and spacer formation before fin epitaxial growth. This establishes a pre-defined trench structure with spacers that prevents fin bending during subsequent processing, as the fins grow within the constrained geometry rather than being formed after STI annealing that causes bending.
Solution Approach 2:
The patent segments the fin formation process into distinct stages: (1) STI planarization, (2) spacer layer deposition, (3) horizontal spacer removal, and (4) fin epitaxial growth. This segmentation allows each step to be optimized independently, ensuring straight fin profiles by separating the structural preparation from the fin growth itself.
2Manufacturing precision
If current fin shaping process is used, then fins can be formed, but tapered profile results
Solution Approach 1:
The patent uses a spacer layer as an intermediary structure that defines the fin profile. The conformal spacer deposited on STI regions and horizontal spacer portions act as a template that guides epitaxial Si growth, ensuring uniform fin width and straight profile rather than relying on direct patterning that causes tapering.
Solution Approach 2:
The patent changes the physical state and geometry parameters by forming a conformal spacer layer with controlled thickness (3-8 nm) and then selectively removing horizontal portions. This parameter control of spacer geometry directly determines the fin profile, enabling uniform width fins through precise thickness and removal parameter optimization.
3Length of moving object
If narrow fin width (6-8 nm) is targeted, then device scaling is achieved, but fin bending susceptibility increases
Solution Approach 1:
The patent applies preliminary anti-action by creating a pre-defined trench structure with spacers before fin growth that counteracts the bending forces that would otherwise affect narrow fins. The spacers provide mechanical support and geometric constraints that prevent bending during STI processing, enabling narrow fin width (6-8 nm) to be achieved without sacrificing straightness.
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 method prevents fin bending and enables the formation of straight fins with uniform or differential widths, suitable for advanced semiconductor devices beyond the 7 nm technology node.
Implementation Method 1
forming a conformal spacer layer over the STI regions and in the recesses
Implementation Method 2
forming a conformal spacer layer over the STI regions and in the recesses
Implementation Method 3
epitaxially growing Si in each recess, forming fins
Implementation Method 4
planarizing the STI regions
Data Source
AI summary
Methods for forming fins with a straight profile by preventing fin bending during STI fill and annealing are disclosed. Embodiments include providing STI regions separated by Si regions, each topped with a hardmask; planarizing the STI regions; removing the hardmask over a portion of the Si regions, forming recesses; forming a conformal spacer layer over the STI regions and in the recesses; removing horizontal portions of the spacer layer; epitaxially growing Si in each recess, forming fins; and etching the STI regions and a remainder of the spacer layer down to the Si regions to reveal the fins.