Silicon Carbide Device 2-Layer Protective Film for Surface Flatness
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for activation heat treatment of silicon carbide substrates often result in surface roughness due to insufficient protection, as conventional protective films like carbon films can crack or have inadequate thickness and quality, leading to vaporization of silicon atoms and subsequent surface roughness.
Innovation Solution
A 2-layer protective film structure is used, comprising a silicon film formed by sputtering in an argon gas atmosphere and a carbon or carbon nitride film, where the silicon film supplies atoms to prevent vaporization and the carbon film provides additional protection, with specific thicknesses and deposition conditions to ensure effective surface protection during high-temperature heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a carbon film is used as a protective film during activation heat treatment, then surface roughness is reduced, but the carbon film may crack or have insufficient thickness leading to vaporization of silicon atoms
Solution Approach 1:
The patent uses a composite protective film structure consisting of a carbon film layer and a silicon-rich silicon carbide layer. The carbon film provides surface protection while the silicon-rich layer prevents silicon atom vaporization. This composite structure combines the advantages of both materials to achieve both surface flatness and film integrity during high-temperature activation heat treatment.
Solution Approach 2:
The protective film is divided into two functional layers: an outer carbon film layer for surface protection and an inner silicon-rich silicon carbide layer for preventing silicon vaporization. This segmentation allows each layer to perform its specific function optimally, with the carbon layer providing chemical stability and the silicon-rich layer providing silicon atom replenishment during heat treatment.
2Quantity of substance
If activation heat treatment is performed at high temperature (1600-1800°C) without protective film, then impurity activation is achieved, but surface roughness occurs due to silicon atom vaporization
Solution Approach 1:
The protective film structure is formed in advance before the activation heat treatment process. The carbon film and silicon-rich silicon carbide layer are prepared beforehand to prevent silicon atom vaporization during the high-temperature treatment, ensuring both impurity activation and surface flatness are achieved simultaneously.
Solution Approach 2:
The silicon-rich silicon carbide layer acts as an intermediary between the silicon carbide substrate and the external environment during heat treatment. It supplies silicon atoms to the substrate surface, preventing silicon vaporization and maintaining surface flatness while allowing the heat treatment to proceed at the required high temperature for impurity activation.
3Ease of manufacture
If conventional single-layer carbon film is used, then deposition is simple, but film quality and thickness are insufficient to prevent silicon vaporization
Solution Approach 1:
Instead of using a simple single-layer carbon film, the patent employs a composite structure with a carbon film layer and a silicon-rich silicon carbide layer. This composite approach maintains relative simplicity in the deposition process while significantly improving film quality and ability to prevent silicon vaporization during heat treatment.
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
The 2-layer protective film structure significantly suppresses surface roughness of silicon carbide substrates by preventing silicon atom vaporization and maintaining surface flatness, enhancing the reliability of silicon carbide semiconductor devices.
Implementation Method 1
a first protective film that is formed in the surface of the semiconductor substrate and supplies atoms that become insufficient in the semiconductor substrate consequent to heat treating
Implementation Method 2
a second protective film that is formed in a surface of the first protective film and suppresses vaporization of silicon atoms from the first protective film
Implementation Method 3
forming a protective film in the surface implanted with the impurity; the first protective film is formed by sputtering in an argon gas atmosphere
Data Source
AI summary
A method of manufacturing a silicon carbide semiconductor device includes ion implanting an impurity into a surface of a semiconductor substrate comprised of silicon carbide, forming a protective film in the surface implanted with the impurity, and heat treating the semiconductor substrate covered by the protective film to activate the impurity. During formation of the protective film, the protective film has a 2-layer structure including a first protective film in the surface of the semiconductor substrate that supplies atoms that become insufficient in the semiconductor substrate as a result of the heat treating, and a second protective film in a surface of the first protective film that suppresses vaporization of silicon atoms from the first protective film. The first protective film may be a silicon film and the second protective film may be a carbon film or a carbon nitride film.