Multi-Layer Dielectric Trench Refill for Shadowing Control
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Solution Overview
Problem
As feature sizes in semiconductor devices decrease, forming thin insulating layers becomes challenging, leading to reduced semiconductor device yield and performance due to issues like air gaps and shadowing effects during the fabrication process.
Innovation Solution
A multi-layer dielectric structure is used to fill trenches completely and account for variations in removal processes, such as polysilicon removal, to prevent shadowing effects and improve profile control, thereby enhancing semiconductor device yield and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-layer dielectric structure is used to fill trenches, then the fabrication process is simpler, but shadowing effects and air gaps occur leading to reduced device yield
Solution Approach 1:
The dielectric structure is divided into multiple layers with different materials (e.g., first dielectric material and second dielectric material) that have different etch selectivities. This segmentation allows each layer to be optimized for specific functions and enables controlled removal of portions to prevent shadowing effects while maintaining fill integrity, thereby improving device yield without significantly complicating the overall fabrication process.
Solution Approach 2:
The patent employs composite dielectric structures combining multiple materials with different properties. The first dielectric material and second dielectric material are selected to have different etch rates and characteristics, allowing the composite structure to fill trenches effectively while enabling selective removal to eliminate air gaps and shadowing effects, thus improving reliability without proportionally increasing manufacturing complexity.
2Reliability
If thin insulating layers are formed in strategic locations, then device performance is improved, but formation challenges arise leading to reduced yield
Solution Approach 1:
The multi-layer dielectric structure allows different regions to have different material compositions and thicknesses optimized for their specific functions. Thin insulating layers can be formed in strategic locations where needed, with each layer's thickness and material properties locally optimized, while the overall structure maintains the precision required for high-performance devices.
Solution Approach 2:
The patent utilizes changes in material parameters (etch selectivity, thickness, material composition) across different layers to achieve precise control over the final dielectric structure. By selecting materials with different etch rates and forming layers with controlled thicknesses, the process achieves precise thin layer formation in strategic locations, improving both manufacturing precision and device performance.
3Reliability
If multi-layer dielectric structure is used to control profile, then shadowing effects are reduced and yield improves, but device complexity increases
Solution Approach 1:
The dielectric structure is segmented into multiple layers that can be independently formed and removed. This segmentation enables precise profile control and elimination of shadowing effects through selective removal of specific layers, improving yield while keeping each individual layer relatively simple in structure and fabrication.
Solution Approach 2:
The patent employs partial removal of dielectric material through selective etching of specific layers. Rather than forming a single complex layer, the process forms multiple layers and then selectively removes portions to achieve the desired profile, reducing shadowing effects and improving yield while maintaining simpler individual layer structures.
Data Source
AI summary
A semiconductor device and method of fabricating a semiconductor device involves formation of a trench above a fin (e.g. a fin of a FinFET device) of the semiconductor device and formation of a multi-layer dielectric structure within the trench. The profile of the multi-layer dielectric structure can be controlled depending on the application to reduce shadowing effects and reduce cut failure risk, among other possible benefits. The multi-layer dielectric structure can include two layers, three layers, or any number of layers and can have a stepped profile, a linear profile, or any other type of profile.