Dummy Fin Formation Using Flowable Oxide for Fin Gap Filling
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Solution Overview
Problem
The semiconductor industry faces challenges in gap filling between high aspect ratio semiconductor fins due to fin-to-fin bending and the formation of seams and voids caused by single ALD high-k films, which can degrade AC performance and lead to RC delay.
Innovation Solution
A bi-layer approach using atomic layer deposition (ALD) of a high-k dielectric layer and a flowable oxide layer is employed to form a dummy fin, reducing intermolecular forces and preventing fin-to-fin bending, while maintaining better shape profile control and lower k-value to preserve AC performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single ALD high-k film is used to fill gaps between high aspect ratio semiconductor fins, then gap filling is achieved, but fin-to-fin bending and formation of seams and voids occur
Solution Approach 1:
The single high-k film layer is segmented into multiple alternating layers of high-k material and porous low-k material. This segmentation reduces the continuous intermolecular forces that cause fin bending while maintaining gap filling functionality. The porous low-k layers act as spacers that prevent the high-k layers from pulling adjacent fins together.
Solution Approach 2:
The patent uses composite material structure combining high-k dielectric material layers with porous low-k dielectric material layers. This composite approach allows the structure to benefit from the high dielectric constant of high-k materials for performance while the low-k porous layers reduce intermolecular attraction forces that cause fin bending and void formation.
2Quantity of substance
If a single ALD high-k film is used for gap filling, then dielectric constant is high, but seams and voids form degrading AC performance
Solution Approach 1:
The continuous high-k film is segmented into discrete high-k layers separated by porous low-k layers. This segmentation prevents the formation of large continuous regions that are prone to forming seams and voids, thereby improving AC performance while maintaining overall high dielectric constant through the stacked high-k layers.
Solution Approach 2:
Different regions of the gap fill structure have different material properties: high-k material regions provide high dielectric constant for performance, while porous low-k material regions provide mechanical support and prevent defect formation. This local differentiation of material quality optimizes both dielectric performance and structural reliability.
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 effectively reduces the formation of seams and voids, prevents fin-to-fin bending, and lowers the dielectric constant of the dummy fin, thereby enhancing AC performance and reducing RC delay.
Implementation Method 1
depositing a first high-k dielectric layer conformally over the fins and in the trenches between the fins using atomic layer deposition
Implementation Method 2
depositing a flowable oxide layer in the trenches over the first high-k dielectric layer using a chemical vapor deposition process
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 flow able 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.