Nitrogen-Doped Silicon Melt Preparation for Uniform BMD Control
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Solution Overview
Problem
Existing methods for doping silicon melt with nitrogen result in non-uniform nitrogen distribution, leading to inconsistent Bulk Micro Defect (BMD) density and impaired Intrinsic Getter effect in silicon wafers.
Innovation Solution
A method involving the preparation of polysilicon particles with uniform sizes, chemical reaction to form a silicon nitride coating on the particles, and controlled melting to achieve uniform nitrogen distribution in the silicon melt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon nitride blocks are placed at the bottom of the quartz crucible and polysilicon feedstock is placed above, then nitrogen doping is achieved, but the nitrogen distribution in the melt becomes non-uniform
Solution Approach 1:
The invention divides the nitrogen source into multiple small silicon nitride blocks distributed throughout the polysilicon feedstock, rather than using a single large block at the bottom. This segmentation ensures nitrogen is released uniformly throughout the melt volume, resolving the non-uniform nitrogen distribution problem while maintaining adequate nitrogen content.
Solution Approach 2:
The invention creates different local configurations by mixing silicon nitride blocks with polysilicon feedstock blocks in a specific arrangement. Each local region contains nitrogen sources distributed among the polysilicon blocks, ensuring that nitrogen dissolves uniformly from all locations rather than concentrating near the bottom crucible.
2Quantity of substance
If nitrogen is doped into silicon melt, then Bulk Micro Defect density increases, but the control over BMD density distribution becomes inconsistent
Solution Approach 1:
By segmenting the nitrogen source into multiple small distributed blocks, the invention ensures consistent nitrogen concentration throughout the melt, which translates to uniform BMD density distribution. This eliminates the inconsistency in BMD control that occurs with non-uniform nitrogen distribution.
Solution Approach 2:
The invention changes the physical arrangement parameter of the nitrogen source from a concentrated bottom placement to a distributed mixed placement. This parameter change ensures uniform nitrogen dissolution kinetics throughout the melt, leading to consistent BMD density and distribution that can be reliably controlled.
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
Achieves uniform nitrogen concentration in the silicon melt, enabling effective control of BMD density and enhancing the Intrinsic Getter effect in silicon wafers.
Implementation Method 1
chemical reaction to form a silicon nitride coating on the particles
Implementation Method 2
nitrogen atoms from silicon nitride blocks B2 cannot be fully dissolved in the whole melt
Data Source
AI summary
Embodiments of the present disclosure disclose an acquisition equipment and a method for acquiring a nitrogen-doped silicon melt, and a system for manufacturing a nitrogen-doped monocrystalline silicon. The acquisition equipment comprises: a granulation apparatus, which is configured to prepare a plurality of polysilicon particles with uniform particles sizes using polysilicon feedstock blocks; a reaction apparatus, which is configured to enable the plurality of polysilicon particles and nitrogen gas to be subjected to chemical reaction to obtain a plurality of reaction particles, wherein silicon nitride is formed in surface layer of each of the plurality of polysilicon particles by the chemical reaction such that each of the plurality of reaction particles includes a polysilicon core and a silicon nitride coating on the polysilicon core; a melting apparatus, which is configured to melt the plurality of reaction particles to obtain the nitrogen-doped silicon melt comprising silicon atoms and nitrogen atoms.