Dual Work Function Gate Structure for GIDL Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices face challenges in reducing gate-induced drain leakage (GIDL) current and improving current drivability, which affects their performance, especially as they become more integrated.
Innovation Solution
A semiconductor device with a dual work function gate structure is developed, featuring a gate electrode with a first work function liner made of titanium aluminum nitride and a second work function liner of N-type impurity-doped polysilicon, along with an air gap between the second work function liner and the junction region, to reduce GIDL and enhance current drivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional gate structure is used in highly integrated semiconductor devices, then device integration is achieved, but gate-induced drain leakage (GIDL) current increases and current drivability deteriorates
Solution Approach 1:
The gate electrode is segmented into two distinct work function liners: a first work function liner (e.g., titanium nitride) and a second work function liner (e.g., tungsten silicide). This segmentation allows different regions of the gate to have different work functions, enabling suppression of GIDL current at specific locations while maintaining overall device functionality.
Solution Approach 2:
Different work function liners are applied to different regions of the gate electrode based on local requirements. The first work function liner is used in regions where GIDL suppression is critical, while the second work function liner is used in regions where current drivability is prioritized. This local differentiation resolves the contradiction by optimizing each region for its specific function.
2Reliability
If a conventional gate structure is used, then manufacturing simplicity is maintained, but current drivability deteriorates
Solution Approach 1:
The gate electrode is divided into multiple segments with different work function liners, each optimized for specific performance characteristics. This segmentation improves current drivability by enabling precise control of carrier injection at different gate regions, despite the increased structural complexity.
Solution Approach 2:
The gate electrode employs a composite structure combining different materials (e.g., titanium nitride and tungsten silicide) with distinct work functions. This composite approach enables superior current drivability by leveraging the complementary properties of each material, accepting the trade-off of increased manufacturing complexity.
3Productivity
If high integration is pursued, then device density increases, but gate-induced drain leakage becomes more significant
Solution Approach 1:
As devices are scaled and integrated at higher densities, the dual work function gate structure applies localized quality control by using different work function liners in different spatial regions of the gate. This allows GIDL suppression to be targeted at specific high-risk regions that become more prominent in highly integrated devices, maintaining device density while mitigating GIDL effects.
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
The dual work function gate structure effectively suppresses gate-induced drain leakage and improves current drivability, leading to enhanced performance and refresh characteristics in memory cells, particularly in DRAM applications.
Implementation Method 1
a first work function liner over the vertical channel region and including an aluminum-containing metal nitride; a second work function liner over the second junction region and including a silicon-containing non-metal material
Data Source
AI summary
A semiconductor device includes a body including a first junction region; a pillar positioned over the body, and including a vertical channel region and a second junction region over the vertical channel region; a gate trench exposing side surfaces of the pillar; a gate dielectric layer covering the gate trench; and a gate electrode embedded in the gate trench, with the gate dielectric layer interposed therebetween. The gate electrode includes a first work function liner overlapping with the vertical channel region, and including an aluminum-containing metal nitride; a second work function liner overlapping with the second junction region, and including a silicon-containing non-metal material; and an air gap positioned between the second work function liner and the second junction region.