Silicon Carbide Thin Film Formation via Segmented Sputtering and Plasma Conversion
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Solution Overview
Problem
Existing methods for forming silicon carbide thin films, such as reactive sputtering and CVD, face inefficiencies, high production costs, and safety concerns, while also being unsuitable for substrates with low heat resistance and requiring high temperatures, and resulting films have poor transmissivity and film strength.
Innovation Solution
A radical assisted sputtering method where a silicon carbide thin film is formed by independently controlling target sputtering and plasma exposure in a vacuum, using a film formation apparatus with separate regions for sputtering and plasma processing, allowing for the repeated formation and conversion of interlayer thin films into ultrathin films using a mixed gas of inert gas and hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reactive sputtering method is used to form silicon carbide thin film, then film can be formed on substrate, but sputtering efficiency is extremely poor and production time becomes long
Solution Approach 1:
The patent divides the film formation process into two separate stages: (1) sputtering stage where silicon and carbon are deposited as separate layers or mixed layers in inert gas atmosphere, and (2) plasma exposure stage where hydrogen plasma converts the sputtered layers into silicon carbide. This segmentation allows each stage to be optimized independently, achieving high formation speed while maintaining good film quality
Solution Approach 2:
Hydrogen plasma acts as an intermediary that transforms the sputtered silicon and carbon layers into silicon carbide. The plasma provides reactive hydrogen species that facilitate the chemical conversion without requiring high substrate temperature, thus enabling efficient film formation with good quality
2Productivity
If CVD method is used to form SiC thin film, then film can be formed, but SiH4 is self ignitable and production procedure becomes dangerous
Solution Approach 1:
The patent uses inert gas atmosphere (argon or nitrogen) during the sputtering process to deposit silicon and carbon layers, eliminating the need for flammable silicon-containing gases like SiH4. The hydrogen plasma is generated separately and does not require high-temperature conditions that would cause self-ignition, thus ensuring safe production procedure while maintaining film formation capability
3Productivity
If CVD method is used to form SiC thin film, then film can be formed, but substrate temperature must be set high (e.g., 1400°C) which is not suitable for plastic substrates or low heat resistance substrates
Solution Approach 1:
The patent replaces the thermal field (high-temperature CVD process) with a plasma field (low-temperature plasma exposure process). Hydrogen plasma provides the necessary chemical reactivity at low temperatures to convert sputtered silicon and carbon into silicon carbide, enabling film formation on heat-sensitive substrates like plastics without requiring high substrate temperature
4Productivity
If sputtering is performed in mixed atmosphere of inert gas and hydrogen, then film conversion can occur, but transmissivity and film strength become poor
Solution Approach 1:
The patent segments the process into distinct sputtering and plasma exposure stages, with sputtering performed in inert gas atmosphere to ensure good film quality and high transmissivity, followed by separate plasma exposure to achieve film conversion. This segmentation prevents the quality degradation that occurs when sputtering is performed directly in hydrogen-containing atmosphere
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 method enables the efficient and safe formation of silicon carbide thin films with high transmissivity and film strength on low heat-resistant substrates, suitable for optical applications, achieving transmissivity of 70% or higher and Vickers hardness of 1300 or higher.
Implementation Method 1
a method of forming a silicon type thin film (SiO2, SiC and Si3N4, etc.) on a substrate by using a so-called reactive sputtering method of introducing a reaction gas (O2, N2 and CH4, etc.) together with an inert gas (Ar) during sputtering a Si target
Implementation Method 2
exposing the interlayer thin film (or bringing the interlayer thin film contact) with plasma generated in an atmosphere of a mixed gas of an inert gas and hydrogen to bring film conversion into an ultrathin film
Data Source
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AI summary
A film deposition method of a silicon carbide thin film having a high transmissivity and high film strength applicable for optical use purposes is provided, by which a film can be formed safely and efficiently in a short time also on a substrate having low heat resistance,. The method of the present invention is a method for depositing a silicon carbide thin film on a moving substrate S by using a film formation apparatus 1 configured that a reaction process region 60 and film formation process regions 20 and 40 are arranged spatially separated from one another in a vacuum container 11 and processing in the regions 20, 40 and 60 can be controlled independently, wherein silicon targets 29a and 29b are sputtered in the region 20 and carbon targets 49a and 49b are sputtered in the region 40. Thereby, an interlayer thin film containing silicon and carbon is formed on the substrate S. Next, in the region 60, the interlayer thin film is exposed to plasma generated in an atmosphere of a mixed gas of an inert gas and hydrogen so as to convert the interlayer thin film into an ultrathin film. Then, the ultrathin film is subjected to successive formation of another interlayer thin film and successive film conversion into an ultrathin film repeatedly.