Nickel Silicide Gate Stack for Low Threshold Voltage Control
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Solution Overview
Problem
The existing techniques for manufacturing semiconductor devices with Ni-FUSI/SiON or high-k gate insulating film structures face challenges in achieving low threshold voltage and complex manufacturing processes due to high processing temperatures and complicated procedures.
Innovation Solution
A method involving the formation of nickel silicides with specific compositions and aluminum segregation at the interface between the nickel silicide and gate insulating films, allowing for independent optimization of nickel silicide forming reactions and aluminum diffusion, thereby reducing the threshold voltage and simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high processing temperature is used to form nickel silicide for low threshold voltage, then the threshold voltage can be reduced, but the manufacturing process complexity increases
Solution Approach 1:
The manufacturing process is divided into separate stages: first forming nickel silicide with a specific composition, then independently optimizing aluminum diffusion in a subsequent stage. This segmentation allows each process to be optimized separately, reducing overall manufacturing complexity while achieving the desired low threshold voltage.
Solution Approach 2:
The patent changes the composition parameters of nickel silicide to specific ratios that facilitate aluminum diffusion at lower processing temperatures. By adjusting the nickel to silicon ratio and controlling the crystalline phase, the material properties are optimized to enable low-temperature aluminum segregation, thereby reducing threshold voltage without requiring high processing temperatures that would complicate the manufacturing process.
2Manufacturing precision
If nickel silicide composition is optimized for aluminum diffusion, then threshold voltage is reduced, but the process becomes more complex
Solution Approach 1:
The nickel silicide is formed with a predetermined composition and crystalline phase structure before aluminum diffusion. This preliminary preparation ensures that the nickel silicide has the optimal properties for subsequent aluminum segregation, allowing the diffusion process to proceed efficiently at lower temperatures and simplifying the overall manufacturing process.
Solution Approach 2:
The patent creates a composite structure where aluminum is segregated at the interface between nickel silicide and the gate insulating film. This composite arrangement at the material level enables precise control of the work function and threshold voltage while maintaining a relatively simple manufacturing process, as the aluminum segregation occurs naturally during low-temperature processing of the pre-formed nickel silicide.
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 production of semiconductor devices with low threshold voltage and simplified manufacturing procedures, optimizing the nickel silicide composition for easy aluminum diffusion in n-channel transistors and restricting it in p-channel transistors, resulting in improved performance and reduced complexity.
Implementation Method 1
diffusing aluminum in the first nickel silicide so as to segregate the aluminum at an interface between the first nickel silicide and the first gate insulating film
Data Source
AI summary
It is made possible to provide a method for manufacturing a semiconductor device that includes CMISs each having a low threshold voltage Vth and a Ni-FUSI/SiON or high-k gate insulating film structure. The method comprises: forming a p-type semiconductor region and an n-type semiconductor region insulated from each other in a substrate; forming a first and second gate insulating films on the p-type and n-type semiconductor regions, respectively; forming a first nickel silicide having a composition of Ni/Si<31/12 above the first gate insulating film, and a second nickel silicide having a composition of Ni/Si≧31/12 on the second gate insulating film; and segregating aluminum at an interface between the first nickel silicide and the first gate insulating film by diffusing aluminum through the first nickel silicide.