Semiconductor Gate Electrodes with Metal Silicide Interconnect
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Solution Overview
Problem
Conventional semiconductor devices with dual-gate electrodes face issues with impurity interdiffusion between n-type and p-type polysilicon electrodes, leading to variations in threshold voltage due to incomplete separation by tungsten films.
Innovation Solution
A semiconductor device structure featuring isolated n-type and p-type gate electrodes separated by an insulating film and connected through a metal silicide film, preventing impurity interdiffusion and ensuring electrical connection without additional wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tungsten silicide film is used to separate n-type and p-type polysilicon electrodes, then electrical connection is maintained, but impurity interdiffusion cannot be completely prevented
Solution Approach 1:
The gate electrode structure is segmented into three distinct layers: n-type polysilicon, tungsten silicide, and p-type polysilicon. This segmentation creates physical barriers that prevent impurity interdiffusion while maintaining electrical connection through the tungsten silicide layer.
Solution Approach 2:
The gate electrode uses a composite structure combining n-type polysilicon, tungsten silicide, and p-type polysilicon layers. Each material contributes specific properties: n-type and p-type polysilicon provide semiconductor functionality, while tungsten silicide provides both electrical conductivity and impurity barrier properties.
2Reliability
If additional wiring is added to connect gate electrodes, then electrical connection is ensured, but device complexity increases
Solution Approach 1:
The tungsten silicide layer serves multiple functions simultaneously: it acts as an electrical conductor to connect the n-type and p-type gate electrodes, and as an impurity barrier to prevent diffusion between the polysilicon regions. This multi-functionality eliminates the need for separate connection wiring.
Solution Approach 2:
The electrical connection function and impurity barrier function are merged into a single tungsten silicide layer. This integration simplifies the overall device structure by combining what would otherwise require separate components into one element.
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 structure effectively suppresses impurity interdiffusion, maintaining consistent threshold voltage and enabling the fabrication of semiconductor devices with desired characteristics, even at high temperatures, while allowing for reduced device size and improved fabrication yield.
Implementation Method 1
the n-type impurity and the p-type impurity introduced into the boundary portion between the polysilicon electrodes may interdiffuse in the polysilicon, when a heat treatment process is performed... the tungsten silicide film is divided on the boundary portion between the n-type polysilicon electrode and the p-type polysilicon electrode... so as to suppress interdiffusion of the impurities
Implementation Method 2
the n-type impurity and the p-type impurity introduced into the boundary portion between the polysilicon electrodes may interdiffuse in the polysilicon, when a heat treatment process is performed after the formation of the n-type polysilicon electrode 109A and the p-type polysilicon electrode 109B
Data Source
AI summary
A semiconductor device includes: an isolation region formed in a semiconductor substrate; a first active region and a second active region surrounded by the isolation region; an n-type gate electrode and a p-type gate electrode formed on gate insulating films; an insulating film and a silicon region formed on the isolation region and isolating the n-type gate electrode and the p-type gate electrode from each other; and a metal silicide film formed on the upper surfaces of the n-type gate electrode, the silicon region, the p-type gate electrode, and part of the insulating film formed therebetween. The n-type gate electrode is electrically connected to the p-type gate electrode through the metal silicide film.