Multilayer Gate Structure for Leakage Control in Semiconductor Devices
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Solution Overview
Problem
As semiconductor devices integrate more densely, they face challenges in reducing leakage current while maintaining reliability, particularly in three-dimensional transistors with recessed or embedded gate structures.
Innovation Solution
A semiconductor device design featuring a substrate with active and element isolation regions, where gate trenches are embedded with a multilayer structure comprising conductive materials of different work functions, including a first conductivity-type semiconductor layer, a conductive layer, and a second conductivity-type semiconductor layer, stacked within the trenches to reduce gate-induced drain leakage and improve data retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistor size is decreased to increase integration density, then productivity is improved, but leakage current increases and reliability deteriorates
Solution Approach 1:
The gate structure is segmented into multiple conductivity-type layers (first conductivity-type semiconductor layer and second conductivity-type semiconductor layer) with different work functions. This segmentation allows each layer to independently control leakage current in different voltage regions, enabling effective leakage suppression even as transistor size decreases and integration density increases.
Solution Approach 2:
Different portions of the gate structure are assigned different conductivity types and work functions. The first conductivity-type layer has a higher work function to suppress leakage in one voltage region, while the second conductivity-type layer has a lower work function to control leakage in another voltage region. This local differentiation of electrical properties enables precise control of leakage current throughout the operating voltage range.
2Reliability
If conventional single-layer gate structure is used, then device complexity is low, but leakage current cannot be sufficiently reduced
Solution Approach 1:
The gate structure uses a composite of multiple semiconductor layers with different conductivity types and work functions. This composite structure combines the advantages of different materials to achieve superior leakage current suppression across the entire operating voltage range, overcoming the limitations of single-material gate structures while maintaining compatibility with existing semiconductor fabrication processes.
3Reliability
If gate-induced drain leakage is not controlled, then manufacturing is simpler, but data retention deteriorates and row hammer phenomena occur
Solution Approach 1:
The gate is divided into multiple conductivity-type layers that can independently control the electric field distribution in different voltage regions. This segmentation prevents excessive electric field concentration at the drain junction, thereby suppressing gate-induced drain leakage and preventing row hammer phenomena that would otherwise cause data retention problems.
Solution Approach 2:
The invention changes the work function parameter of the gate structure by using multiple layers with different work functions. This parameter change optimizes the electric field distribution and potential profile, effectively reducing gate-induced drain leakage and improving data retention without requiring fundamental changes to the device architecture.
Data Source
AI summary
A semiconductor device includes a substrate including an active region and an element isolation region defining the active region, a gate trench extending into the element isolation region and penetrating the active region, and a gate structure filling the gate trench and including a first conductivity-type semiconductor layer, a conductive layer, and a second conductivity-type semiconductor layer, sequentially stacked from a lower portion of the gate trench.