Semiconductor Contact Work Function Control via Conformal Layer Thickness
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Solution Overview
Problem
As feature sizes of transistors decrease and shapes become three-dimensional, it becomes difficult to control the distribution of implanted ions for adjusting threshold voltage, affecting the operating characteristics of transistors.
Innovation Solution
The semiconductor device includes transistors with contacts having work function control layers of different thicknesses and materials, formed conformally on the contact holes, to achieve distinct work functions and improve operating characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If work function control layers of different thicknesses are formed on contact holes, then distinct work functions are achieved, but manufacturing process complexity increases
Solution Approach 1:
The patent segments the work function control into separate layers for different contacts. The first work function control layer is formed on the first contact hole and the second work function control layer is formed on the second contact hole, allowing independent thickness and material optimization for each contact type
Solution Approach 2:
The work function control layers serve multiple functions: they control the work function of different contacts, enable threshold voltage adjustment, and maintain conformal coverage on 3D transistor structures. This multi-functionality reduces the need for separate specialized structures
Data Source
AI summary
A semiconductor device and a method of fabricating the same are provided. The semiconductor device includes a substrate including a first region and a second region, a first transistor and a second transistor formed on the first region and the second region, respectively, a first contact formed on the first transistor, and a second contact formed on the second transistor. The first contact includes a first work function control layer having a first thickness and a first conductive layer formed on the first work function control layer, the second contact includes a second work function control layer having a second thickness different from the first thickness and a second conductive layer formed on the second work function control layer, and the first contact and the second contact have different work functions.