Semiconductor Gate Structure with Hydrogen Plasma Impurity Removal
Solution Overview
Problem
As semiconductor devices evolve with shrinking gate and channel lengths, there is a need to enhance capacitance between the gate and channel and improve operating characteristics, particularly in metal-oxide-semiconductor (MOS) transistors, where polysilicon gate electrodes exhibit high resistance and lower speed compared to metal gate electrodes.
Innovation Solution
A method for fabricating semiconductor devices involves forming a first work function control film with impurities on a high-k layer, reducing impurity concentration by up to 90% using hydrogen plasma doping, and subsequently forming a gate metal within a trench structure to adjust the work function and surface resistance of the gate electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a polysilicon gate electrode is used, then the gate can withstand high temperature annealing and form self-aligned source and drain structures, but the gate exhibits high resistance and lower operating speed
Solution Approach 1:
The gate electrode is segmented into multiple layers: a bottom polysilicon layer that provides thermal stability and self-alignment, and a top metal layer that provides low resistance and high-speed operation. This segmentation allows each layer to fulfill its specific function without compromise.
Solution Approach 2:
The gate electrode uses a composite structure combining polysilicon and metal materials. The polysilicon portion provides thermal stability and self-alignment capabilities, while the metal portion contributes low resistance and high-speed characteristics, achieving a synergistic effect that resolves the contradiction between reliability and speed.
2Speed
If a metal gate electrode is used, then the gate exhibits low resistance and high operating speed, but the gate cannot withstand high temperature annealing and self-aligned source and drain formation
Solution Approach 1:
The gate electrode is segmented into multiple layers: a bottom polysilicon layer that provides thermal stability and self-alignment, and a top metal layer that provides low resistance and high-speed operation. This segmentation allows each layer to fulfill its specific function without compromise.
Solution Approach 2:
The gate electrode uses a composite structure combining polysilicon and metal materials. The polysilicon portion provides thermal stability and self-alignment capabilities, while the metal portion contributes low resistance and high-speed characteristics, achieving a synergistic effect that resolves the contradiction between reliability and speed.
3Ease of manufacture
If impurities are present in the work function control film, then the film formation process is simpler, but the surface resistance increases by 30% to 60%
Solution Approach 1:
Impurities are intentionally introduced into the work function control film during the deposition process, and then removed in a subsequent dedicated removal step. This preliminary introduction simplifies the initial film formation, while the later removal step ensures low surface resistance, resolving the contradiction between manufacturing ease and electrical performance.
Solution Approach 2:
The impurity concentration in the work function control film is dynamically controlled through a two-stage process: first allowing impurity incorporation during deposition for simplicity, then removing impurities through plasma treatment or annealing to achieve the desired low resistance, thus optimizing both manufacturing ease and electrical characteristics.
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 reduces the flatband voltage and surface resistance of the gate structure by 30% to 60%, improving the operating characteristics of MOS transistors and enabling better performance in semiconductor devices.
Implementation Method 1
removing the impurities by doping hydrogen into the first work function control film using hydrogen plasma
Implementation Method 2
doping hydrogen into the first work function control film using hydrogen plasma
Data Source
AI summary
Provided are methods for fabricating semiconductor devices. The methods for fabricating the semiconductor devices may include forming a first interlayer insulation film including a trench on a substrate, forming a high-k layer along an inner sidewall and a bottom surface of the trench, forming a first work function control film including impurities along the high-k layer, removing the impurities from the first work function control film to reduce surface resistance of the first work function control film by about 30% to about 60% and forming a gate metal in the trench.