Multi-Layer Dielectric Refill for FinFET Trench Profile 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
1Length of moving object
If thin insulating layers are formed in semiconductor devices, then feature size decreases and device density increases, but air gaps and shadowing effects occur leading to reduced yield
Solution Approach 1:
The dielectric structure is divided into multiple layers (first dielectric layer and second dielectric layer) with different widths. The first dielectric layer has a wider width than the second dielectric layer, creating a stepped profile. This segmentation allows each layer to be optimized independently - the wider first layer prevents air gaps during polysilicon removal while the narrower second layer provides the required electrical isolation, thus resolving the contradiction between small feature size and manufacturing reliability
Solution Approach 2:
The invention transitions from a single-layer dielectric structure to a multi-layer stepped structure, adding vertical dimensionality to the dielectric profile control. By creating different width levels in the vertical stacking direction, the patent achieves precise profile control that prevents both air gaps and shadowing effects, thereby improving yield while maintaining small feature sizes
2Device complexity
If single-layer dielectric structure is used, then device complexity is low, but profile control is insufficient leading to shadowing effects
Solution Approach 1:
The dielectric structure is segmented into multiple layers with progressively narrower widths from bottom to top. The first dielectric layer extends wider than the second dielectric layer, creating a controlled stepped profile. This segmentation enables precise profile control that prevents shadowing effects during subsequent fabrication steps, demonstrating that increased structural complexity directly improves manufacturing precision
Solution Approach 2:
Different regions of the dielectric structure are given different widths and functions. The first dielectric layer provides broader coverage for mechanical support and air gap prevention, while the second dielectric layer provides focused electrical isolation. This local differentiation of structural properties achieves superior profile control without requiring uniform complexity throughout the entire structure
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.