Semiconductor Fin Gap Filling With Bi-Layer Dummy Fin Formation
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Solution Overview
Problem
The use of a single atomic layer deposition (ALD) high-k film to fill gaps between semiconductor fins in high aspect ratio structures leads to fin-to-fin bending, seam formation, and voids, which degrade AC performance and cause RC delay.
Innovation Solution
A bi-layer approach using a high-k dielectric layer and a flowable oxide layer deposition is employed to form a dummy fin, providing better shape profile control and reducing fin bending, seam, and void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single ALD high-k film is used to fill gaps between fins, then gap filling is achieved, but fin-to-fin bending, seam formation, and voids occur
Solution Approach 1:
The patent divides the gap filling process into multiple stages: first forming a flowable oxide layer that fills gaps without causing bending, then performing recesses to create controlled spaces, and finally depositing high-k material in subsequent layers. This segmentation prevents the harmful intermolecular forces from acting on the fins during the entire filling process, eliminating fin-to-fin bending while achieving complete gap filling.
Solution Approach 2:
The patent performs preliminary actions by first depositing the flowable oxide layer and forming recesses before introducing the high-k material. This preliminary structuring creates a controlled environment where the high-k material can be deposited without causing fin bending, seams, or voids, thereby improving both gap filling quality and fin structural integrity.
2Reliability
If high-k material is deposited to fill trenches between fins, then dielectric properties are improved, but AC performance degrades due to RC delay
Solution Approach 1:
The patent applies local quality by using different materials in different locations: the flowable oxide layer is used in the initial gap filling where structural support is needed, while high-k material is deposited in subsequent layers in controlled amounts where dielectric properties are needed. This localized material selection optimizes both dielectric performance and AC characteristics by minimizing RC delay while maintaining reliable dielectric properties.
3Manufacturing precision
If flowable oxide is deposited and recessed, then shape profile control is improved, but process complexity increases
Solution Approach 1:
The patent utilizes parameter changes by controlling the deposition thickness and recess depth parameters of the flowable oxide layer. By optimizing these parameters, the process achieves excellent shape profile control and eliminates fin bending despite the additional process steps. The parameter optimization makes the increased process complexity worthwhile by delivering superior manufacturing precision.
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
The bi-layer method enhances semiconductor fin integrity, preserves AC performance, and reduces RC delay by avoiding intermolecular forces between high-k regions on neighboring fins.
Implementation Method 1
forming a first high-k layer conformally over the dielectric layer by introducing a bi-layer approach using an atomic layer deposition (ALD) of a high-k dielectric layer
Implementation Method 2
forming a flowable oxide layer deposition... in which forming the flowable oxide layer includes filling first trenches adjacent fins of the plurality of fins
Data Source
AI summary
A method of manufacturing a semiconductor device includes forming a dielectric layer conformally over a plurality of fins on a substrate, forming a first high-k layer conformally over the dielectric layer, and forming a flowable oxide over the first high-k layer. Forming the flowable oxide includes filling first trenches adjacent fins of the plurality of fins. The method further includes recessing the flowable oxide to form second trenches between adjacent fins of the plurality of fins, forming a second high-k layer over the first high-k layer and the flowable oxide, performing a planarization that exposes top surfaces of the plurality of fins, and recessing the dielectric layer to form a plurality of dummy fins that include remaining portions of the first and second high-k layers and the flowable oxide.