Work Function Control Film for CMOS Gate Electrodes
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Solution Overview
Problem
Fabricating complementary metal oxide semiconductor (CMOS) devices with different p-channel and n-channel metal oxide semiconductor (PMOS and NMOS) work functions is challenging due to the need for multiple films in the replacement metal gate process.
Innovation Solution
A method is developed to use a single work function control film, specifically aluminum (Al) or aluminum nitride, to control the work functions of PMOS and NMOS by injecting appropriate materials through annealing or ion implantation, allowing for the formation of metal gate electrodes with distinct work functions in each region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple films are deposited in a trench during the replacement metal gate process to achieve different work functions for PMOS and NMOS, then the work function differentiation is achieved, but the device complexity and manufacturing process complexity increase
Solution Approach 1:
The patent merges the work function control for both PMOS and NMOS into a single film structure. The gate electrode includes a first portion and a second portion formed from the same continuous film, where the work function difference is achieved through selective doping or material composition within the single film rather than stacking multiple separate films. This reduces the number of film layers while maintaining the required work function differentiation.
Solution Approach 2:
The patent applies local quality by creating different work functions in different regions of the same gate electrode film. The first portion of the gate electrode has a first work function and the second portion has a second work function, achieved through selective doping concentrations or material composition variations within the single film structure. This allows region-specific property control without increasing overall film stack complexity.
2Manufacturing precision
If multiple films are deposited in a trench during the replacement metal gate process to achieve different work functions for PMOS and NMOS, then the work function differentiation is achieved, but the manufacturing process complexity increases
Solution Approach 1:
The patent combines multiple film deposition steps into a single film formation process. Instead of depositing separate films for different work functions, a single gate electrode film is deposited and then differentiated through selective doping or material modification in specific regions. This merging of steps simplifies the manufacturing process while achieving the same functional result.
Solution Approach 2:
The patent changes material parameters (doping concentration, material composition) within the single gate electrode film to achieve different work functions in different regions. By controlling the doping level or composition in the first portion versus the second portion, the work function is tuned locally without requiring separate film deposits, thereby simplifying the manufacturing process.
3Device complexity
If a single work function control film is used to achieve different work functions for PMOS and NMOS, then the device complexity is reduced, but the manufacturing precision for work function control becomes more challenging
Solution Approach 1:
The patent achieves precise work function control in a single film by implementing local quality variations. The gate electrode film has a first portion with a first work function and a second portion with a second work function, created through selective doping or material composition control during or after film formation. This localized property control enables precise work function differentiation without requiring multiple films.
Solution Approach 2:
The patent controls the work function precision by changing material parameters (doping concentration, stoichiometry) within the single gate electrode film. By precisely controlling the doping level or composition in different regions of the film, the work function is accurately tuned to achieve the required differentiation between PMOS and NMOS regions, maintaining manufacturing precision despite using a single film structure.
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 approach enables the fabrication of CMOS devices with different work functions for PMOS and NMOS using a single film, reducing the number of stacked films and preventing aperture clogging, while maintaining superior barrier characteristics and reducing resistance.
Implementation Method 1
injecting a work function control material into the work function control film formed in the first region
Implementation Method 2
injecting a work function control material into the work function control film formed in the first region to control a work function of the work function control film formed in the first region
Data Source
AI summary
A method of fabricating a semiconductor device may include: preparing a substrate in which first and second regions are defined; forming an interlayer insulating film, which includes first and second trenches, on the substrate; forming a work function control film, which contains Al and N, along a top surface of the interlayer insulating film, side and bottom surfaces of the first trench, and side and bottom surfaces of the second trench; forming a mask pattern on the work function control film formed in the second region; injecting a work function control material into the work function control film formed in the first region to control a work function of the work function control film formed in the first region; removing the mask pattern; and forming a first metal gate electrode to fill the first trench and forming a second metal gate electrode to fill the second trench.