Silicon Substrate Carbon Doping for Gettering and Defect Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for producing silicon semiconductor substrates with high-concentration boron and nitrogen doping face challenges in achieving uniform gettering ability and suppressing epitaxial defects, particularly due to boron and nitrogen segregation, which affects device yield and performance.
Innovation Solution
Doping carbon or carbon and nitrogen during the Czochralski method pulling process, and performing appropriate heat treatments prior to the epitaxial process, to control the formation of ring-shaped oxygen-induced stacking faults and promote oxygen precipitates, thereby ensuring uniform and high-level gettering ability across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-concentration boron and nitrogen are doped in the silicon substrate, then gettering ability is improved, but epitaxial defects are generated due to segregation
Solution Approach 1:
The patent applies local quality by creating a specific doping concentration distribution where boron and nitrogen are concentrated in the lower portion of the substrate (near the surface) while maintaining lower concentrations in the upper portion. This spatial differentiation of doping concentrations optimizes gettering ability at the interface while preventing epitaxial defects in the growth region, resolving the contradiction between these two requirements.
Solution Approach 2:
The patent changes the doping concentration parameters by establishing a gradient distribution rather than uniform doping. Specifically, it controls the boron concentration to be 1×10^18 to 1×10^20 atoms/cm³ and nitrogen concentration to be 1×10^19 to 1×10^21 atoms/cm³ in the lower portion, while maintaining lower concentrations above these values in the upper portion. This parameter optimization prevents segregation-induced defects while maintaining gettering effectiveness.
2Reliability
If oxygen concentration is increased to promote oxygen precipitates, then gettering ability is enhanced, but ring-shaped OSF region is generated
Solution Approach 1:
The patent applies local quality by creating a spatially differentiated oxygen concentration distribution. Oxygen is concentrated in the lower portion of the substrate (near the surface) where it promotes beneficial oxygen precipitates for gettering, while maintaining lower oxygen concentrations in the upper portion to prevent ring-shaped OSF formation. This local differentiation resolves the contradiction between enhancing gettering and preventing defects.
Solution Approach 2:
The patent optimizes oxygen concentration parameters by establishing a gradient: oxygen concentration is controlled to be 1×10^18 to 1×10^20 atoms/cm³ in the lower portion to promote precipitates, while maintaining 1×10^17 to 1×10^19 atoms/cm³ in the upper portion to prevent OSF. This parameter optimization resolves the contradiction between gettering enhancement and defect prevention.
3Ease of manufacture
If uniform doping is applied across the substrate, then manufacturing simplicity is maintained, but non-uniform gettering ability results due to segregation
Solution Approach 1:
The patent applies local quality by intentionally creating non-uniform doping distributions tailored to different substrate regions. The lower portion receives higher boron and nitrogen concentrations for gettering, while the upper portion maintains lower concentrations for defect-free epitaxial growth. This spatially differentiated approach achieves uniform gettering ability across the substrate interface while preventing segregation-induced non-uniformity.
Solution Approach 2:
The patent changes the doping parameters from uniform to gradient distribution. Boron concentration is controlled at 1×10^18 to 1×10^20 atoms/cm³ and nitrogen at 1×10^19 to 1×10^21 atoms/cm³ in the lower portion, transitioning to lower concentrations in the upper portion. This parameter optimization ensures uniform gettering performance while preventing segregation effects that would otherwise create non-uniformity.
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 epitaxial defects and enhances gettering ability, allowing for higher oxygen concentrations and improved device characteristics, leading to increased production yield and reduced defect generation.
Implementation Method 1
promote oxygen precipitates (BMD: a bulk micro defect) by doping carbon or carbon along with nitrogen in a pulling process of the Czochralski method
Implementation Method 2
in a pulling process of the Czochralski method (hereinafter referred to as 'CZ method')
Implementation Method 3
performing appropriate heat treatments prior to the epitaxial process
Implementation Method 4
when the epitaxial layer is formed on the silicon semiconductor substrate
Data Source
AI summary
The present invention can provide a silicon semiconductor substrate used for and epitaxial wafer, in which uniform and high-level gettering ability is obtained irrespective of slicing positions from a silicon single crystal while generation of epitaxial defects can be suppressed, by doping carbon or carbon along with nitrogen during a pulling process of a CZ method or by performing appropriate heat treatment prior to the epitaxial process. Therefore, a crystal production yield can remarkably be improved because a permissible upper limit (concentration margin) of an oxygen concentration which is restricted by formation of a ring-shaped OSF region can be higher and also an excellent gettering ability is exhibited, while allowing an epitaxial wafer to be produced wherein epitaxial defects attributable to substrate crystal defects are not formed.