Graphite Crucible with Vertical Slits for Silicon Melting
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Solution Overview
Problem
Existing graphite crucibles for silicon melting suffer from carbon contamination and crucible cleavage due to reactions between silicon and graphite, while cold copper crucibles face heat loss issues, making them inefficient for electromagnetic induction-based silicon melting.
Innovation Solution
A graphite crucible with a cylindrical body and multiple vertical slits in both the inner and outer walls, allowing electromagnetic induction to prevent silicon melt contact with the crucible walls, combined with indirect heating for efficient melting and refining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If indirect melting with heat from graphite crucible is used, then silicon can be melted, but carbon contamination occurs and crucible cleavage happens
Solution Approach 1:
The patent extracts the harmful interaction between silicon melt and graphite crucible by introducing vertical slits that allow electromagnetic force to act directly on the silicon melt, preventing contact with the crucible walls while maintaining heating efficiency
Solution Approach 2:
The patent uses electromagnetic induction as an intermediary mechanism to transfer energy to the silicon melt without requiring direct contact with the graphite crucible, thereby eliminating carbon contamination while preserving the heating function
2Object-affected harmful factors
If cold copper crucible is used to prevent contact between silicon melt and crucible, then contamination is prevented, but heat loss occurs
Solution Approach 1:
The patent replaces the mechanical cooling system of cold copper crucible with electromagnetic induction heating that acts directly on the silicon melt through vertical slits, eliminating the need for cooling water and associated heat losses while preventing contamination
Solution Approach 2:
The patent changes the thermal parameters by using vertical slits to enable direct electromagnetic heating of the silicon melt, transforming the heat transfer mechanism from conductive heating through crucible walls to direct electromagnetic induction, thereby eliminating heat loss
3Use of energy by moving object
If graphite crucible is used for electromagnetic induction heating, then heating efficiency is improved, but silicon melt contacts inner wall causing contamination
Solution Approach 1:
The patent segments the crucible wall by introducing vertical slits that divide the continuous graphite structure into separated regions, allowing electromagnetic force to penetrate through the slits and act on the silicon melt without requiring the melt to contact the inner wall surface
Solution Approach 2:
The patent introduces a new spatial dimension by creating vertical slits that extend through the crucible wall thickness, enabling electromagnetic induction to act on the silicon melt from the outside without requiring direct contact through the inner wall surface
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
The crucible design enhances melting efficiency and purity by minimizing contact between silicon and graphite, reducing contamination, and eliminating heat loss, achieving high-purity silicon refining with reduced crucible wear.
Implementation Method 1
When an alternating current is applied to an induction coil wound around a crucible to induce magnetic field variation, an induction current is created on the surface of metal to be melted thereby inducing Joule heating
Implementation Method 2
an induction current is created on the surface of metal to be melted thereby inducing Joule heating
Implementation Method 3
the induction current interacts with a magnetic field to generate Lorentz force in the molten metal
Implementation Method 4
graphite is a non-metallic material, it has very high electric and thermal conductivity, thereby allowing the crucible to be easily heated through electromagnetic induction
Data Source
AI summary
Disclosed herein are a graphite crucible for electromagnetic induction-based silicon melting and an apparatus for silicon melting/refining using the same, which performs a melting operation by a combination of indirect melting and direct melting. The crucible is formed of a graphite material and includes a cylindrical body having an open upper part through which a silicon raw material is charged into the crucible, and an outer wall surrounded by an induction coil, wherein a plurality of slits are vertically formed through the outer wall and an inner wall of the crucible such that an electromagnetic force created by an electric current flowing in the induction coil acts toward an inner center of the crucible to prevent a silicon melt from contacting the inner wall of the crucible.