Silicon Wafer Defect Control via Temperature Gradient and Hydrogen Doping
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Solution Overview
Problem
The challenge in manufacturing silicon single crystals for semiconductor wafers is the presence of Grown-in defects, such as vacancy defects and dislocation clusters, which affect the performance and yield of integrated circuits, particularly with the miniaturization of circuits requiring defect-free areas over the entire wafer surface.
Innovation Solution
A method involving the Czochralski process with a hot zone structure where the temperature gradient is larger in the center than the periphery, combined with controlled hydrogen partial pressure and doping of nitrogen or carbon, to extend the defect-free area and uniformly form Bulk Micro-Defects (BMD) across the wafer surface, thereby reducing Grown-in defects and improving wafer quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the pull-up speed is increased to improve productivity, then the manufacturing efficiency is improved, but Grown-in defects such as IR scatterer and dislocation cluster increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the pull-up speed within a specific range (0.2-0.6 mm/min) and maintaining the temperature gradient (G/V ratio) between 2.0-4.0 °C/(mm/min) to minimize Grown-in defects while ensuring sufficient productivity. This optimization of process parameters resolves the contradiction between manufacturing efficiency and defect reduction.
2Reliability
If the defect-free area is extended to the entire wafer surface for miniaturized circuits, then the device performance is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by creating a uniform temperature distribution across the entire crystal growth cross-section, ensuring that the entire wafer surface achieves defect-free quality suitable for miniaturized circuits. This is accomplished through optimized heater configuration and heat insulation structures that maintain consistent thermal conditions throughout the growth zone.
3Manufacturing precision
If thermal treatment is applied to remove Grown-in defects, then the defect-free area is improved, but the treatment time and energy consumption increase
Solution Approach 1:
The patent applies preliminary action by preventing Grown-in defect formation during the crystal growth process itself through optimized temperature control and pull-up speed management. By addressing the defect prevention proactively during growth rather than requiring extensive post-growth thermal treatment, the method reduces treatment time and energy consumption while achieving defect-free wafers.
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 enables the production of silicon wafers with significantly reduced Grown-in defects, enhancing the yield and performance of integrated circuits by ensuring a defect-free area over the entire wafer surface, which is crucial for further miniaturization and higher density of circuits.
Implementation Method 1
growing a silicon single crystal by immersing and pulling up seed crystal in and from molten silicon within a quartz crucible
Implementation Method 2
growing a single crystal by immersing and pulling up seed crystal in and from molten silicon
Implementation Method 3
a hot zone structure where the temperature gradient is larger in the center than the periphery
Implementation Method 4
adding a gas made of a hydrogen atom-containing substance to an atmosphere gas within a growing apparatus
Implementation Method 5
doping nitrogen and/or carbon in the crystal
Data Source
AI summary
A silicon single crystal is manufactured by growing said crystal composed of a defect-free area free from the Grown-in defects by the CZ process, adding a gas of a hydrogen atom-containing substance to an atmosphere gas within a growing apparatus, and doping nitrogen and/or carbon in the crystal. Therefore, a wafer the whole surface of which is composed of the defect-free area free from the Grown-in defects and which can sufficiently and uniformly form BMD can be easily sliced. Such a wafer can be extensively used, since it can significantly reduce generation of characteristic defectives of integrated circuits to be formed thereon and contribute for improving the production yield as a substrate responding to the demand for further miniaturization and higher density of the circuits.