FinFET Gate Electrode Grid Pattern for Uniform Etching
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Solution Overview
Problem
Existing FinFET devices face challenges in achieving uniform etching and reducing the loading effect during the fabrication process, which affects the grid-like pattern formation of gate electrodes and can lead to undesirable gate-leakage issues due to non-uniform etching depths across different exposed areas.
Innovation Solution
The FinFET device structure incorporates a gate electrode with a grid-like pattern and the use of dummy gate electrodes with a pitch similar to the main gate electrodes, along with a capping layer to control etching and reduce the loading effect, ensuring uniform etching and effective electrical isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used on gate electrodes with varying exposed areas, then etching proceeds at different rates across different regions, but this results in non-uniform etching depths and gate-leakage issues
Solution Approach 1:
Dummy gate electrodes are formed in advance alongside the main gate electrodes before the etching process. These dummy structures are specifically designed to match the pitch and spacing of the main gates, creating a uniform pattern that pre-compensates for the loading effect during subsequent etching operations.
Solution Approach 2:
The patent introduces dummy gate electrodes that create a homogeneous pattern across the substrate. By ensuring that both main and dummy gates have identical geometric characteristics and spacing, the etching process experiences uniform loading conditions throughout, eliminating the non-uniform etching depths that would otherwise occur in regions with varying exposed areas.
2Productivity
If gate electrodes are formed with standard spacing, then device density is maintained, but the loading effect causes non-uniform etching across different gate regions
Solution Approach 1:
The gate electrode system is segmented into two functional groups: main gate electrodes that perform the primary device function, and dummy gate electrodes that serve solely to provide etching support. This segmentation allows the main gates to maintain high device density while the dummy gates compensate for etching non-uniformity, effectively decoupling the density requirement from the etching uniformity requirement.
Solution Approach 2:
Dummy gate electrodes are created as exact copies of the main gate electrode geometry and spacing pattern. These copied structures replicate the loading conditions of the main gates during etching, ensuring that the etching process experiences identical conditions across all gate regions, thereby achieving uniform etching depths without compromising device density.
3Manufacturing precision
If capping layers are applied to all gate structures, then etching uniformity is improved, but additional process steps and structural complexity are introduced
Solution Approach 1:
The dummy gate electrodes serve multiple functions: they provide etching support to improve uniformity, maintain pitch consistency, and can be subsequently removed or retained based on design requirements. By making the dummy structures multi-functional, the patent achieves etching uniformity without requiring additional specialized process steps beyond the standard gate formation and etching sequence.
Data Source
AI summary
A fin field effect transistor (FinFET) device structure and method for forming FinFET device structure are provided. The FinFET structure includes a substrate and a fin structure extending above the substrate. The FinFET structure also includes a gate electrode formed over the fin structure, and the gate electrode has a grid-like pattern when seen from a top-view.