Boron-Doped Silicon Wafer Composition for Low-Defect Epitaxy
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Solution Overview
Problem
The challenge is to create a silicon wafer with extremely low resistivity and high gettering ability while minimizing epitaxial defects, particularly stacking faults, which arise from high oxygen concentrations during epitaxial growth.
Innovation Solution
The silicon wafer is optimized with a boron concentration of 8.5×10^18 atoms/cm^3 or more and an oxygen concentration of 14.5×10^17 atoms/cm^3 or more, along with a carbon concentration of 2×10^16 atoms/cm^3 or more, to achieve a high BMD density and suppress epitaxial defects by forming an epitaxial layer with a resistivity of 1 mΩ·cm or less and 10 mΩ·cm or more, and ensuring the wafer is free from COPs and dislocation clusters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the oxygen concentration in the silicon wafer is increased to achieve high BMD density (1×10^9 precipitates/cm³ or more), then the gettering ability is improved, but numerous stacking faults occur in the epitaxial layer during epitaxial growth
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxygen concentration within a specific range (1.45×10^18 to 1.65×10^18 atoms/cm³) and boron concentration (8.5×10^18 to 1.05×10^19 atoms/cm³) to simultaneously achieve high BMD density for gettering while suppressing stacking faults in the epitaxial layer. This quantitative parameter optimization resolves the contradiction between improving gettering ability and maintaining epitaxial quality.
2Reliability
If the boron concentration is increased to achieve extremely low resistivity (1 mΩ·cm or less and 10 mΩ·cm or more), then the latch-up countermeasure effectiveness is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by defining a specific boron concentration range (8.5×10^18 to 1.05×10^19 atoms/cm³) that achieves the desired resistivity (1-10 mΩ·cm) for effective latch-up prevention. This controlled parameter specification balances the need for low resistivity with manufacturing feasibility, resolving the contradiction between reliability improvement and manufacturing complexity.
3Reliability
If the BMD density is increased to provide additional gettering capability for lower temperature heat treatment, then the heavy metal impurity trapping is improved, but the stacking fault density in the epitaxial layer increases
Solution Approach 1:
The patent resolves this contradiction by optimizing the oxygen concentration to a narrow range (1.45×10^18 to 1.65×10^18 atoms/cm³) that enables sufficient BMD formation for heavy metal trapping while simultaneously suppressing stacking fault generation during epitaxial growth. This precise parameter control allows both gettering capability and epitaxial quality to be maintained.
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 configuration enables the formation of silicon wafers with high gettering ability and suppresses epitaxial defects, resulting in a high-quality epitaxial layer suitable for semiconductor device fabrication with improved device performance.
Implementation Method 1
Gettering technology is one of the techniques to reduce these heavy metal impurities. One of these gettering techniques is known as intrinsic gettering (IG), in which oxygen precipitates, or bulk micro defects (BMDs), are formed within the silicon wafer for trapping heavy metal impurities therein.
Implementation Method 2
PTL 1 states that addition of carbon increases the BMD density and improves the gettering ability.
Data Source
AI summary
To provide a silicon wafer with extremely low resistivity by containing an ultra-high concentration of boron, the silicon wafer having a high gettering ability by enabling formation of oxygen precipitates at a high concentration, and making it possible to suppress the occurrence of epitaxial defects originating from oxygen precipitates when an epitaxial layer is formed. Disclosed is a silicon wafer made of monocrystalline silicon, the silicon wafer containing boron as a dopant and having a resistivity of 1 mΩ·cm or more and 10 mΩ·cm or less, the silicon wafer having an oxygen concentration of 14.5×1017 atoms/cm3 or more and 16×1017 atoms/cm3 or less, and a carbon concentration of 2×1016 atoms/cm3 or more and 5×1017 atoms/cm3 or less, and the silicon wafer being free from COPs and dislocation clusters.