3D Vertical Transistor Oxidation with Oxygen-Rich Silicon Surface
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Solution Overview
Problem
Conventional methods for producing vertical transistors with three-dimensional structures face issues such as increased electrical resistance and deteriorated electrical characteristics due to silicon emission during heat treatment, caused by low oxygen concentrations in the silicon substrate surface layer, leading to a narrow core and irregular interfaces between the oxide film and the core.
Innovation Solution
A method involving a silicon substrate with a surface layer oxygen concentration of 1×10^17 atoms/cm^3 or more, where a heat treatment forms a uniform oxide film by diffusing oxygen from the substrate, preventing silicon emission and creating a smooth interface, thereby enhancing electrical characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a heat treatment is performed on a silicon substrate with low oxygen concentration (1×10^16 atoms/cm³ or less), then an oxide film can be formed on the surface, but silicon is emitted from the three-dimensional shape causing the core to become narrow and electrical resistance to increase
Solution Approach 1:
The patent applies preliminary action by pre-introducing oxygen into the silicon substrate surface layer before the heat treatment process. This preliminary oxygen introduction ensures that when heat treatment is performed, oxygen is already available at the surface to combine with silicon atoms, preventing silicon emission and core narrowing while still allowing oxide film formation.
Solution Approach 2:
The patent changes the oxygen concentration parameter in the silicon substrate surface layer from 1×10^16 atoms/cm³ or less to 1×10^17 atoms/cm³ or more. This parameter change fundamentally alters the heat treatment process outcome, enabling oxide film formation without silicon emission, core narrowing, or electrical resistance increase.
2Manufacturing precision
If a heat treatment is performed to form an oxide film, then the oxide film can be created on the three-dimensional shape, but projections and recesses are formed on the interface between the oxide film and the core causing electrical characteristics to deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-introducing oxygen into the silicon substrate surface layer before heat treatment. This ensures that oxygen is available during the oxidation process to maintain a smooth interface between the oxide film and core, preventing the formation of projections and recesses that would deteriorate electrical characteristics.
Solution Approach 2:
The patent changes the oxygen concentration parameter to 1×10^17 atoms/cm³ or more, which fundamentally improves the interface quality during heat treatment. This parameter change enables uniform oxide film growth and smooth interface formation, eliminating projections and recesses while maintaining excellent 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 suppresses silicon emission during heat treatment, reduces electrical resistance, and improves the smoothness of the oxide film-core interface, resulting in transistors with excellent electrical performance and reduced power consumption.
Implementation Method 1
oxygen of a surface layer diffuses outward
Implementation Method 2
oxygen atms necessary for forming the oxide film can be supplied from the silicon substrate as well as the heat treatment atmosphere simultaneously
Data Source
AI summary
A method for producing a three-dimensional structure, a method for producing a vertical transistor, a vertical transistor wafer, and a vertical transistor substrate, capable of suppressing the emission of Si due to a heat treatment and making an interface between an oxide film and a core mainly consisting of Si relatively smooth include: forming a three-dimensional shape by processing (for example, by etching) a surface layer of a monocrystalline silicon substrate, the surface layer having an oxygen concentration of 1×1017 atoms/cm3 or more; and then forming an oxide film on the surface of the three-dimensional shape by performing a heat treatment. The three-dimensional structure has a shape having projections and recesses in a thickness direction of the silicon substrate, and a height in the thickness direction of the silicon substrate is between 1 nm and 1000 nm, and preferably between 1 nm and 100 nm.