Transistor Gate Isolation via Protection Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As the critical dimension of MOS transistors decreases, the distance between adjacent gate structures and conductive plugs deteriorates, leading to poor isolation performance and electrical properties due to the deterioration of the electrical properties between the gate electrode layer and the conductive plugs.
Innovation Solution
A method involving the formation of a work function layer on the side surfaces and bottom of an opening in the interlayer dielectric layer, followed by the removal of a portion of the work function layer to create grooves and the deposition of a protection layer with lower electrical conductivity than the work function layer, which enhances the isolation performance by replacing the work function layer on the side surfaces of the gate electrode layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the critical dimension is reduced to increase transistor density, then productivity is improved, but the distance between gate structures and conductive plugs decreases leading to deterioration of isolation performance
Solution Approach 1:
The patent applies local quality by forming a protection layer with different material properties (lower electrical conductivity) specifically in the region between the gate electrode layer and conductive plugs. This localized modification addresses the isolation performance issue only where needed, without changing the properties of other transistor components. The protection layer is formed selectively over the interlayer dielectric layer in the specific region requiring enhanced isolation.
Solution Approach 2:
The protection layer acts as an intermediary element between the gate electrode layer and the conductive plugs. This intermediate layer provides additional isolation functionality, mediating the electrical interaction between these two components. The protection layer's lower electrical conductivity compared to the work function layer enables it to serve as an effective barrier, preventing unwanted electrical coupling while allowing the transistor to maintain high density.
2Reliability
If the work function layer is removed from side surfaces to improve isolation, then electrical properties are improved, but the threshold voltage control may be affected
Solution Approach 1:
The patent applies local quality by selectively removing the work function layer only from the side surfaces of the gate electrode layer, while preserving it in other regions. This selective removal enhances isolation performance in specific areas without completely eliminating the work function layer's contribution to threshold voltage control. The protection layer is then formed locally to provide the necessary isolation functionality.
Solution Approach 2:
The patent segments the work function layer into different functional regions: the side surface portions are removed to improve isolation, while the bottom and other regions are retained for threshold voltage control. This segmentation allows different parts of the work function layer to serve different purposes, resolving the contradiction between isolation performance and threshold voltage control.
Data Source
AI summary
A transistor is provided and includes a substrate; a first interlayer dielectric layer disposed on the substrate, the first interlayer dielectric layer including an opening there-through; a work function layer at least disposed over a bottom of the opening; a gate electrode layer disposed in the opening and over the work function layer; and a protection layer disposed on the work function layer and between the gate electrode layer and the first interlayer dielectric layer.