FinFET Dummy Gate Structure for Lower Seam Density
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Solution Overview
Problem
Existing FinFET devices face challenges in forming a three-dimensional strained channel, particularly in reducing the density of coalescence boundaries or seams in the dummy gate, which affects the quality of the metal gate.
Innovation Solution
The method involves forming a dummy gate with a trench dummy and a blanket dummy, where the trench dummy is formed through a deposition-etching cycle and treated thermally to reduce coalescence boundary density, and the blanket dummy is formed over the trench dummy with a micro-polycrystalline structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a dummy gate is formed using conventional photolithography and deposition processes, then the manufacturing process is simple, but the density of coalescence boundaries or seams in the dummy gate is high, affecting metal gate quality
Solution Approach 1:
The dummy gate is divided into two separate components: a trench dummy gate formed in gate trenches and a blanket dummy gate formed over the substrate. This segmentation allows each component to be optimized independently, with the trench dummy gate providing structural support and the blanket dummy gate providing a continuous surface, thereby reducing coalescence boundaries while maintaining manufacturing feasibility
Solution Approach 2:
The invention transitions from a conventional single-layer dummy gate to a two-layer stacked structure with the trench dummy gate in the horizontal dimension and the blanket dummy gate in the vertical dimension. This dimensional change enables better control over grain structure and coalescence boundaries, improving metal gate quality without significantly increasing process complexity
2Manufacturing precision
If the dummy gate is formed with a single continuous layer, then the manufacturing process is straightforward, but the grain distribution and coalescence boundary density are suboptimal
Solution Approach 1:
The dummy gate is segmented into trench and blanket portions that can be formed using slightly different processes. The trench dummy gate is formed in etched trenches allowing controlled grain growth, while the blanket dummy gate is formed as a continuous layer. This segmentation improves grain distribution quality while maintaining reasonable manufacturing ease through standard semiconductor fabrication techniques
Solution Approach 2:
Different regions of the dummy gate structure are given different qualities: the trench dummy gate region provides structural definition with controlled grain size, while the blanket dummy gate region provides a continuous coverage with optimized grain distribution. This local differentiation of quality enables superior overall grain distribution without requiring complete process redesign
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 approach results in a FinFET structure with a reduced density of coalescence boundaries, leading to improved metal gate quality, enhanced grain distribution, and increased efficiency in the FinFET manufacturing process.
Implementation Method 1
changing the phase of the first or second silicon-containing material to micro-polycrystalline
Implementation Method 2
forming a first silicon-containing material within the plurality of trenches
Data Source
AI summary
A semiconductor structure, a method for manufacturing a FinFET structure and a method for manufacturing a semiconductor structure are provided. The method for forming a FinFET structure includes: providing a FinFET precursor including a plurality of fins and a plurality of gate trenches between the fins; forming a first portion of the trench dummy of a dummy gate within the plurality of gate trenches; removing at least a part of the first portion of the trench dummy; forming a second portion of the trench dummy over the first portion of the trench dummy; performing a first thermal treatment to the first and second portions of the trench dummy; and forming a blanket dummy of the dummy gate over the second portion of the trench dummy. The present disclosure further provides a FinFET structure with an improved metal gate.