Nickel Silicide Formation via Silicon Monolayer for Semiconductor Reliability
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Solution Overview
Problem
The existing methods for fabricating semiconductor devices face challenges in forming nickel silicide (NiSi) due to a narrow temperature range, leading to the formation of high-resistance materials like Ni2Si or NiSi2 when there is a slight temperature deviation, which affects the reliability of the device.
Innovation Solution
A method is developed to form a silicon monolayer using SiH4 gas on the semiconductor substrate, which reacts with a nickel layer to form a nickel silicide (NiSi) layer, expanding the temperature range for NiSi formation and ensuring a good-quality silicide layer is achieved, even at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nickel layer is thermally processed to form nickel silicide, then a silicide layer is formed on the source and drain regions, but the temperature range for forming good-quality NiSi is very narrow (400±10°C), causing high-resistance materials like Ni2Si or NiSi2 to form when temperature deviates
Solution Approach 1:
The patent changes the chemical parameters by introducing a silicon layer between the nickel layer and the semiconductor substrate. This modifies the reaction conditions and enables NiSi formation over a broader temperature range (300-500°C) compared to the conventional narrow range (400±10°C), thereby improving reliability while expanding temperature tolerance.
Solution Approach 2:
The patent introduces a silicon layer as an intermediary between the nickel layer and the semiconductor substrate. This intermediary layer controls the diffusion and reaction processes, ensuring that nickel reacts with silicon to form NiSi rather than forming high-resistance compounds like Ni2Si or NiSi2, thus improving the quality and reliability of the silicide layer.
2Ease of manufacture
If the temperature is slightly deviated during thermal processing, then the process becomes easier to control, but high-resistance materials like Ni2Si or NiSi2 are formed instead of NiSi
Solution Approach 1:
The patent modifies the chemical composition parameters by adding a silicon layer, which changes the reaction kinetics and thermodynamics. This allows the process to tolerate temperature deviations (300-500°C range) while still producing the desired NiSi phase, thereby improving ease of manufacture without sacrificing manufacturing precision.
Solution Approach 2:
The silicon layer acts as a cushioning layer that prevents the formation of high-resistance materials even when temperature control is not precise. By having excess silicon available, the system is buffered against temperature variations that would otherwise lead to unwanted phases like Ni2Si or NiSi2, ensuring consistent NiSi formation.
3Use of energy by moving object
If a nickel silicide layer is formed at low temperature, then the process energy consumption is reduced, but the temperature range is limited and may not form quality NiSi
Solution Approach 1:
The patent changes the chemical parameters by introducing a silicon layer, which enables NiSi formation at lower temperatures (300-500°C) while maintaining good quality. The silicon layer facilitates the reaction at lower energies, reducing process energy consumption without compromising the reliability or quality of the nickel silicide layer.
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 allows for the formation of a reliable nickel silicide layer with a broader temperature tolerance, reducing the likelihood of high-resistance material formation and enhancing the overall reliability of the semiconductor device.
Implementation Method 1
forming a silicon layer on an entire surface of the substrate including the gate electrode; forming a conductive layer on the entire surface of the substrate including the silicon layer; forming a silicide layer on the entire surface of the substrate by thermal-processing the substrate such that the conductive layer reacts with the silicon layer
Implementation Method 2
forming a silicide layer on the entire surface of the substrate by thermal-processing the substrate such that the conductive layer reacts with the silicon layer
Data Source
AI summary
A method for fabricating a semiconductor device, including forming a gate insulating layer and a gate electrode on a substrate; forming insulating layer sidewalls at sides of the gate electrode; forming source/drain regions in surface portions of the substrate that are located, respectively, at sides of the gate electrode; forming a conductive silicide layer on the entire surface of the substrate; and selectively removing the silicide layer from areas other than the gate electrode and the source/drain regions of the substrate. The conductive silicide layer may be made by forming a silicon layer on an entire surface of the substrate; forming a conductive layer on the silicon layer; and thermal-processing the substrate such that the conductive layer reacts with the silicon layer.