Czochralski Silicon Wafer Doping with Hydrogen to Suppress Stacking Faults
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Solution Overview
Problem
Lightly boron-doped, p−-doped semiconductor wafers from silicon face challenges in maintaining metallic impurity exclusion and forming sufficient oxygen precipitates due to nitrogen doping, which increases oxidation-induced stacking faults and layer defects, requiring restrictive monitoring and cooling conditions.
Innovation Solution
Doping silicon single crystals with boron, hydrogen, and nitrogen during the Czochralski process, while controlling nitrogen and oxygen concentrations, and using hydrogen to suppress the formation of oxidation-induced stacking faults, allowing for stable nucleation centers and reduced layer defects without high-temperature heat treatments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nitrogen is added to increase nucleation centers for oxygen precipitates, then getter capacity is improved, but oxidation-induced stacking faults and layer defects increase
Solution Approach 1:
The patent applies parameter changes by precisely controlling the nitrogen concentration within a specific range (1×10^14 to 1×10^15 atoms/cm³) and oxygen concentration (1×10^17 to 1×10^18 atoms/cm³) to achieve the desired balance between nucleation center formation and defect prevention. This quantitative parameter control allows the system to generate sufficient oxygen precipitates for getter capacity while avoiding excessive stacking faults and layer defects.
Solution Approach 2:
The patent implements local quality by creating specific regional conditions within the semiconductor wafer. By controlling the concentration gradients of nitrogen and oxygen during crystal growth, the invention establishes zones with different defect characteristics - areas with sufficient nucleation centers for getter capacity while maintaining regions with low layer defect densities suitable for electronic component fabrication.
2Manufacturing precision
If cooling rate is reduced to control oxygen precipitate formation, then nucleation centers are stabilized, but pulling rate must be reduced which decreases productivity
Solution Approach 1:
The patent resolves this contradiction by changing the doping parameters - specifically introducing controlled amounts of nitrogen (1×10^14 to 1×10^15 atoms/cm³) and oxygen (1×10^17 to 1×10^18 atoms/cm³) during crystal growth. This allows the system to achieve stable nucleation centers and controlled oxygen precipitate formation at higher pulling rates without requiring reduced cooling rates, thereby maintaining both manufacturing precision and productivity.
3Object-generated harmful factors
If nitrogen concentration is restricted to low range to reduce layer defects, then oxidation-induced stacking faults are minimized, but nucleation centers for oxygen precipitates become insufficient
Solution Approach 1:
The patent simultaneously adjusts multiple parameters - nitrogen concentration (1×10^14 to 1×10^15 atoms/cm³), oxygen concentration (1×10^17 to 1×10^18 atoms/cm³), and their ratio - to achieve the optimal balance. This multi-parameter optimization allows sufficient nucleation centers to form for getter capacity while keeping nitrogen levels low enough to minimize oxidation-induced stacking faults and layer defects.
Solution Approach 2:
The patent creates a composite doping system combining nitrogen and oxygen at specific concentrations. This composite approach allows the system to leverage the nucleation-center-forming capability of nitrogen while using oxygen to compensate for potential defects and ensure sufficient precipitate formation, achieving both low layer defect densities and adequate getter capacity.
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 p−-doped epi wafers with sufficient getter capacity and low layer defects, suitable for large-scale integrated electronic components, with flexible manufacturing conditions and reduced monitoring requirements.
Implementation Method 1
doping silicon single crystals with boron, hydrogen and nitrogen during the Czochralski process, while controlling nitrogen and oxygen concentrations, and using hydrogen to suppress the formation of oxidation-induced stacking faults
Implementation Method 2
such wafers form insufficient oxygen precipitates (BMDs, bulk micro defects) which ordinarily bond such impurities and in this way act as what are known as intrinsic getters
Implementation Method 3
a silicon single crystal is pulled using the Czochralski method and during this pulling is doped with boron, hydrogen and nitrogen
Implementation Method 4
processed to form p−-doped semiconductor wafers which are epitaxially coated
Data Source
AI summary
The Czochralski method is used for producing p−-doped and epitaxially coated semiconductor wafers from silicon, wherein a silicon single crystal is pulled, and during the pulling is doped with boron, hydrogen and nitrogen, and the single crystal thus obtained is processed to form p−-doped semiconductor wafers which are epitaxially coated.