Plasma Work Function Modulation for Metal Gate Electrodes
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Solution Overview
Problem
Current semiconductor manufacturing techniques face challenges in achieving the precise control of work functions for metal films used in MOSFETs and DRAM capacitors, particularly in adjusting the work function of conductive thin films to optimize power consumption and threshold voltage without adding impurities to three-dimensional structures like Fin FETs.
Innovation Solution
A method involving plasma processing with specific process gases to add or remove elements from metal films, such as TiN and W films, to modulate their work functions, allowing for the formation of gate electrodes with desired work functions by applying masks and performing plasma processing on selective regions of the films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional metal films are used for gate electrodes, then the structure is simple and manufacturing is easy, but the work function cannot be precisely controlled to optimize power consumption and threshold voltage
Solution Approach 1:
The patent changes the chemical composition parameters of the metal film by adding specific elements (Al, Si, Ge) through plasma processing to precisely control the work function. This allows optimization of power consumption and threshold voltage by adjusting element concentration, directly resolving the work function control precision issue while maintaining a relatively simple process flow.
Solution Approach 2:
The patent uses plasma as an intermediary to add desired elements to the metal film. The plasma processing introduces Al, Si, or Ge atoms into the metal film, serving as a mediator to achieve precise work function control without requiring complex multi-step manufacturing processes.
2Manufacturing precision
If elements are added to metal films to adjust work function, then power efficiency and threshold voltage control improve, but the risk of adding impurities to three-dimensional structures increases
Solution Approach 1:
The patent applies local quality by using mask patterns to selectively add elements only to specific regions of the metal film where work function adjustment is needed. This localized plasma processing ensures that Al, Si, or Ge atoms are introduced only where required, preventing impurity contamination in other areas while achieving precise work function control.
3Manufacturing precision
If different metal films are used for different gate electrodes to achieve desired work functions, then work function requirements are met, but the number of materials and process complexity increase
Solution Approach 1:
The patent applies universality by using a single base metal film material (such as TiN, TaN, or W) that can be selectively modified with Al, Si, or Ge elements through plasma processing. This multi-functional approach allows one base material to serve multiple work function requirements, eliminating the need for multiple different metal film materials while maintaining manufacturing simplicity.
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
Enables the formation of gate electrodes with arbitrary work functions, improving power efficiency and threshold voltage control, especially in complex structures like Fin FETs, by precisely adjusting the work function of conductive thin films without altering their elemental composition.
Implementation Method 1
modulating the work function of a first exposed region of the metal film, using plasma of a first process gas
Data Source
AI summary
A process of forming a first mask on a first region of a metal film formed on a surface of a substrate, a process of modulating a work function of a first exposed region of the metal film, using plasma of a first process gas, a process of removing the first mask, a process of forming a second mask on a second region of the metal film, and a process of modulating the work function of a second exposed region of the metal film, using plasma of a second process gas are executed.