Double-Structured Gate Metal for Leakage Reduction
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Solution Overview
Problem
The challenge in semiconductor devices, particularly in DRAM structures, is the high leakage current associated with the gate-induced drain leakage (GIDL) in the off-state, which affects the refresh time and overall performance, especially as the scale of integration increases and the charge storage capacity decreases.
Innovation Solution
A method for fabricating a semiconductor device involves forming a double-structured gate metal with different boron concentrations and work functions by using B2H6 and SiH4 gases for the lower and upper gate metals, respectively, to reduce leakage current and enhance operating efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional single-structure gate metal is used, then the manufacturing process is simple, but the leakage current is high
Solution Approach 1:
The gate metal is divided into two distinct structures: a lower gate metal and an upper gate metal. Each layer serves a specific function - the lower gate metal provides mechanical support and basic electrical connection, while the upper gate metal optimizes electrical characteristics and reduces leakage current. This segmentation allows independent optimization of each layer without compromising the other.
Solution Approach 2:
Different regions of the gate metal structure are assigned different materials and properties. The lower gate metal uses one material composition while the upper gate metal uses another, creating local quality variations that optimize performance at different locations. This allows the structure to have different characteristics where needed - mechanical strength at the bottom and electrical optimization at the top.
2Reliability
If the gate metal structure is optimized to reduce leakage current, then the operating performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The gate metal is divided into two distinct structures: a lower gate metal and an upper gate metal. Each layer serves a specific function - the lower gate metal provides mechanical support and basic electrical connection, while the upper gate metal optimizes electrical characteristics and reduces leakage current. This segmentation allows independent optimization of each layer without compromising the other.
Solution Approach 2:
The patent changes material parameters by selecting different materials for the lower and upper gate metals. By adjusting material composition, thickness, and work function of each layer, the electrical characteristics are optimized to reduce leakage current while maintaining manufacturability through standard deposition processes.
3Loss of energy
If a double-structured gate metal with different materials is used, then the leakage current is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent changes material parameters by selecting different materials for the lower and upper gate metals. By adjusting material composition, thickness, and work function of each layer, the electrical characteristics are optimized to reduce leakage current while maintaining manufacturability through standard deposition processes.
Solution Approach 2:
The gate metal structure uses composite materials with different properties in different layers. The lower gate metal and upper gate metal are composed of different materials selected for their specific properties, creating a composite structure that achieves superior electrical characteristics and leakage current reduction compared to single-material gates.
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 significantly reduces leakage current and improves the operating performance of semiconductor devices by optimizing the gate metal structure, leading to enhanced refresh times and driving efficiency.
Implementation Method 1
forming a lower gate metal using B2H6 gas
Implementation Method 2
forming an upper gate metal on the barrier metal, by using SiH4 gas
Data Source
AI summary
A Semiconductor device and method for fabricating the same are provided. The method includes forming a trench in a substrate, forming a lower gate metal using a first gas, the lower gate metal burying at least a portion of the trench, forming a barrier metal on the lower gate metal, on the barrier metal, forming an upper gate metal using a second gas different from the first gas and forming a capping film on the gate metal, the capping film filling the trench.