Silicon Substrate Thermal Diffusion for Defect Control
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Solution Overview
Problem
High-temperature and long-term thermal diffusion processes in semiconductor manufacturing lead to crystal defects and increased costs due to the need for deep p-type isolation layers, which can reduce the reliability of semiconductor devices and increase manufacturing time.
Innovation Solution
A method involving a silicon semiconductor substrate produced by the floating zone method, where a first heat treatment in an oxygen or mixed oxygen-inert gas atmosphere is followed by a second heat treatment in a nitrogen or mixed nitrogen-oxygen atmosphere to form a deep diffusion layer, reducing crystal defects and minimizing the use of inert gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If high-temperature and long-term thermal diffusion is performed to form deep p-type isolation layers, then the diffusion depth is sufficient, but crystal defects occur and manufacturing time increases
Solution Approach 1:
The thermal diffusion process is divided into multiple sequential stages with different atmosphere conditions. The first stage uses oxygen or mixed oxygen-inert gas atmosphere to form an initial diffusion layer, followed by a second stage using nitrogen or mixed nitrogen-oxygen atmosphere to complete the deep diffusion. This segmentation allows each stage to optimize for its specific purpose, reducing overall crystal defects while achieving the required diffusion depth.
Solution Approach 2:
The first heat treatment in oxygen or mixed oxygen-inert gas atmosphere is performed as a preliminary action before the second heat treatment in nitrogen or mixed nitrogen-oxygen atmosphere. This preliminary treatment prepares the substrate by forming an initial diffusion layer and reducing oxygen content in critical regions, which prevents nitrogen precipitate formation during the subsequent nitrogen-based heat treatment and enables deeper diffusion without excessive crystal defects.
2Length of stationary object
If high-temperature and long-term thermal diffusion is performed to form deep diffusion layers, then the diffusion depth is sufficient, but manufacturing costs increase
Solution Approach 1:
The invention changes the atmospheric parameters (oxygen content, inert gas composition) and temperature parameters across different diffusion stages. By using mixed gas atmospheres with varying oxygen and inert gas ratios, and by optimizing temperature profiles for each stage, the process achieves deep diffusion layers while reducing manufacturing costs through improved process efficiency and reduced defect rates.
3Ease of manufacture
If thermal diffusion is performed in nitrogen atmosphere to form deep diffusion layers, then nitrogen precipitates may form, but the process is simpler
Solution Approach 1:
The first heat treatment in oxygen or mixed oxygen-inert gas atmosphere serves as a preliminary action that reduces oxygen content in the substrate before the nitrogen-based heat treatment. This preliminary oxygen removal prevents nitrogen precipitate formation during the subsequent nitrogen atmosphere treatment, allowing the use of simpler nitrogen-based processes without the harmful side effect of precipitate formation.
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 effectively suppresses crystal defects and reduces manufacturing costs by optimizing the thermal diffusion process, allowing for the formation of deep diffusion layers without nitrogen precipitates, even at high temperatures and extended times.
Implementation Method 1
a diffusion step of thermal diffusion is performed at a heat treatment temperature that is equal to or higher than 1290° C. and is lower than a melting temperature of a silicon crystal to form a diffusion layer with a depth of 50 μm or more
Implementation Method 2
When an oxide film is formed on the surface of the semiconductor substrate, ions are confined in the semiconductor substrate and the dissipation of ions from the surface of the substrate to the outside of the substrate is prevented by thermal diffusion
Implementation Method 3
A silicon semiconductor substrate which is manufactured by a floating zone method
Data Source
AI summary
A method for manufacturing a silicon semiconductor substrate including a diffusion layer prior to forming a semiconductor device thereon, includes providing a silicon semiconductor substrate which is manufactured by a floating zone method; and performing thermal diffusion at a heat treatment temperature that is equal to or higher than 1290° C. and that is lower than a melting temperature of a silicon crystal to form a diffusion layer with a depth of 50 μm or more in the silicon semiconductor substrate, the thermal diffusion including a first heat treatment performed in an atmosphere consisting of oxygen or oxygen and at least one of argon, helium, or neon, followed by a second heat treatment performed in an atmosphere comprised of nitrogen or nitrogen and oxygen to form the diffusion layer. The method suppresses the occurrence of crystal defects, reduces the amount of inert gas used, and reduces manufacturing costs.